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Tomporowski 2003 Acta Psychol (Amst) + (A review was conducted of studies that ass … A review was conducted of studies that assessed the effects of acute bouts of physical activity on adults' cognitive performance. Three groups of studies were constituted on the basis of the type of exercise protocol employed. Each group was then evaluated in terms of information-processing theory. It was concluded that submaximal aerobic exercise performed for periods up to 60 min facilitate specific aspects of information processing; however, extended exercise that leads to dehydration compromises both information processing and memory functions. The selective effects of exercise on cognitive performance are explained in terms of Sanders' [Acta Psychol. 53 (1983) 61] cognitive-energetic model.. 53 (1983) 61] cognitive-energetic model.)
Meunier 1995 Biochemistry + (A screen has been performed of possible in … A screen has been performed of possible inhibitors of the quinol oxidation sites of the two terminal oxidases of ''Escherichia coli'', cytochromes bo and bd. Aurachin C and its analogues were found to be particularly effective inhibitors of both enzymes, whereas aurachin D and its analogues displayed a selectivity for inhibition of cytochrome bd. In addition, a tridecyl derivative of stigmatellin was found to inhibit cytochrome bo at concentrations which were without significant effect on cytochrome bd. Titration of membrane-bound cytochromes bo and bd with aurachin C gave an observed dissociation constant in the range of 10-8 M. A similar observed dissociation constant was determined for aurachin D inhibition of cytochrome bd. For both enzymes, their kinetic behavior during a series of substrate pulses indicates that it is reduction of the enzyme by quinol, and not reaction with oxygen, which is inhibited. It is concluded that the aurachins are powerful inhibitors of the quinol oxidation sites of bacterial cytochromes bo and bd. The effects of aurachin C on cytochrome bo were investigated in more detail. The number of inhibitor binding sites on the purified enzyme was determined by titration to be 0.6 per enzyme. At an inhibitorloxidase ratio of 1.0, electron donation into the enzyme from added quinol is extremely slow, making it very unlikely that there is more than one quinone-reactive site. Aurachin C caused a potent inhibition of electron donation from a pulse of quinol. In contrast, it was without effect on cyanide or carbon monoxide binding to the reduced enzyme, on cyanide binding to the oxidized enzyme, on the optical spectra of the heme groups, or on the kinetics of oxygen reduction after photolysis of carbon monoxide from the reduced enzyme. We conclude that binding of aurachin C specifically inhibits the quinol oxidation site and does not directly affect the properties of the binuclear center.irectly affect the properties of the binuclear center.)
Bers 1982 Am J Physiol + (A simple method for the accurate determina … A simple method for the accurate determination of free [Ca] in ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA)-buffered Ca solutions is described. This method is useful for calibration of Ca macro- and microelectrodes to low free [Ca] and should improve the reliability of calculated free [Ca] in more complex solutions. Briefly, free [Ca] in Ca-EGTA solutions is measured with a Ca electrode, bound Ca is calculated, and Scatchard and double-reciprocal plots are resolved for the total [EGTA] and the apparent Ca-EGTA association constant (K'Ca) in the solutions used. The free [Ca] is then recalculated using the determined parameters, giving a more accurate knowledge of the free [Ca] in these solutions and providing an accurate calibration curve for the Ca electrode. These solutions can then be used to calibrate other Ca electrodes (e.g., Ca microelectrodes) or the calibrated Ca electrode can be used to measure free [Ca] in solutions containing multiple metal ligands. This method allows determination of free [Ca], K'Ca, and total [EGTA] in the actual solutions used regardless of pH, temperature, or ionic strength. It does not require accurate knowledge of K'Ca or EGTA purity and circumvents many potential errors due to assumption of binding parameters. K'Ca was found to be 2.45 +/- 0.04 X 10(6) M-1 in 100 mM KCl, 10 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid, and 1 mM EGTA at pH 7.00 and 23 degrees C. Total [EGTA] varied with supplier but was always less than quoted. supplier but was always less than quoted.)
Stokich 2014 Cryobiology + (A simple method to cryogenically preserve … A simple method to cryogenically preserve hepatocyte monolayers is currently not available but such a technique would facilitate numerous applications in the field of biomedical engineering, cell line development, and drug screening. We investigated the effect of trehalose and dimethyl sulfoxide (Me2SO) in cryopreservation of human hepatocellular carcinoma (HepG2) cells in suspension and monolayer formats. HepG2 cell monolayers were incubated for 24 h at varying concentrations of trehalose (50-150 mM) prior to cryopreservation to identify the optimum concentration for such preincubation. When trehalose alone was used as the cryoprotective agent (CPA), cells in monolayer format did not survive freezing while cells in suspension demonstrated 14% viability 24 h after thawing. Only 6-13% of cells in monolayers survived freezing in cell culture medium supplemented with 10% Me2SO, but 42% of cells were recovered successfully if monolayers were preincubated with 100 mM trehalose prior to freezing in the Me2SO supplemented medium. Interestingly, for cells frozen in suspension in presence of 10% Me2SO, metabolic activity immediately following thawing did not change appreciably compared to unfrozen control cells. Finally, Raman spectroscopy techniques were employed to evaluate ice crystallization in the presence and absence of trehalose in freezing solutions without cells because crystallization may alter the extent of injury observed in cell monolayers. We speculate that biomimetic approaches of using protective sugars to preserve cells in monolayer format will facilitate the development of techniques for long-term preservation of human tissues and organs in the future.of human tissues and organs in the future.)
Small 1985 Biochem J + (A simple spectrophotometric assay was deve … A simple spectrophotometric assay was developed for peroxisomal fatty [[acyl-CoA oxidase]] activity. The assay, based on the H2O2-dependent oxidation of leuco-dichlorofluorescein catalysed by exogenous [[peroxidase]], is more sensitive than methods previously described. By using mouse liver samples, cofactor requirements were assessed and a linear relationship was demonstrated between dye oxidation and enzyme concentration. By using this assay on subcellular fractions, palmitoyl-CoA oxidase activity was localized for the first time in microperoxisomes of rat intestine. The assay was also adapted to measure D-amino acid oxidase activity, demonstrating the versatility of this method for measuring activity of other H2O2-producing oxidases.g activity of other H2O2-producing oxidases.)
Petrova 2014 Proc Chem + (A simple, accurate and rapid voltammetric … A simple, accurate and rapid voltammetric method has been developed for the quantitative determination of coenzyme Q10. Studies with direct current voltammetry were carried out using a glassy carbon electrode (GCE) in a phosphate buffer solution (pH 6.86). A well-defined oxidation peak of CoQ10 was obtained at -0.600 V vs Ag/AgCl. The magnitude of the oxidation peak current has been found to be related to the concentration of the coenzyme over the range of (2·10-5 to 2·10-4 M) (''r'' = 0.991). Antioxidant activity of CoQ10 was investigated.) (''r'' = 0.991). Antioxidant activity of CoQ10 was investigated.)
Lin 2012 FASEB J + (A single high-fat meal acutely increases s … A single high-fat meal acutely increases skeletal muscle mitochondrial H2O2 emitting potential (mEH2O2), shifts the intracellular redox environment to a more oxidized state, and increases circulating markers of oxidative stress. Bioenergetically, this implies an acute lipid load may elevate the reducing pressure/membrane potential ({Delta}{Psi}m) within mitochondria and, conversely, that even a mild increase in energy expenditure may be sufficient to prevent these effects. To test this hypothesis, male Sprague-Dawley rats received an oral lipid gavage (20% intralipid, 45 Kcal/kg lean body mass) or water followed either by 2h of rest or 1h of rest plus 1h of low intensity treadmill exercise (15 m/min, 0% grade). Permeabilized fiber bundles were prepared from red gastrocnemius muscle for testing mitochondrial function. In rats receiving lipid, {Delta}{Psi}m and mEH2O2 were higher (P<0.05) and calcium retention capacity (mCa2+RC, an index of resistance to mitochondrial permeability transition) was lower under state IV and/or "clamped" ADP-stimulated state III conditions. All three effects were prevented when lipid gavage was followed by low-intensity exercise. Respiratory capacity was unaffected by any of the interventions. These findings provide evidence that mitochondrial {Delta}{Psi}m, mEH2O2, and mCa2+RC are acutely affected by nutritional overload in skeletal muscle, but can be prevented by low intensity exercise. NIH DK073488ented by low intensity exercise. NIH DK073488)
Ortega 2017 Biol Reprod + (A single missense mutation at position 159 … A single missense mutation at position 159 of coenzyme Q9 (COQ9) (G→A; rs109301586) has been associated with genetic variation in fertility in Holstein cattle, with the A allele associated with higher fertility. COQ9 is involved in the synthesis of coenzyme COQ10, a component of the electron transport system of the mitochondria. Here we tested whether reproductive phenotype is associated with the mutation and evaluated functional consequences for cellular oxygen metabolism, body weight changes, and ovarian function. The mutation in COQ9 modifies predicted tertiary protein structure and affected mitochondrial respiration of peripheral blood mononuclear cells. The A allele was associated with low resting oxygen consumption and high electron transport system capacity. Phenotypic measurements for fertility were evaluated for up to five lactations in a population of 2273 Holstein cows. There were additive effects of the mutation (P < 0.05) in favor of the A allele for pregnancy rate, interval from calving to conception, and services per conception. There was no association of genotype with milk production or body weight changes ''postpartum''. The mutation in COQ9 affected ovarian function; the A allele was associated with increased mitochondrial DNA copy number in oocytes, and there were overdominance effects for COQ9 expression in oocytes, follicle number, and antimullerian hormone concentrations. Overall, results show how a gene involved in mitochondrial function is associated with overall fertility, possibly in part by affecting oocyte quality.possibly in part by affecting oocyte quality.)
Du 1998 Free Radic Biol Med + (A small portion of the oxygen consumed by … A small portion of the oxygen consumed by aerobic cells is converted to superoxide anion at the level of the mitochondrial respiratory chain. If produced in excess, this harmful radical is considered to impair cellular structures and functions. Damage at the level of mitochondria have been reported after ischemia and reperfusion of organs. However, the complexity of the ''in vivo'' system prevents from understanding and describing precise mechanisms and locations of mitochondrial impairment. An ''in vitro'' model of isolated-mitochondria anoxia-reoxygenation is used to investigate superoxide anion generation together with specific damage at the level of mitochondrial oxidative phosphorylation. Superoxide anion is detected by electron paramagnetic resonance spin trapping with POBN-ethanol. Mitochondrial respiratory parameters are calculated from oxygen consumption traces recorded with a Clark electrode. Respiring mitochondria produce superoxide anion in unstressed conditions, however, the production is raised during postanoxic reoxygenation. Several respiratory parameters are impaired after reoxygenation, as shown by decreases of phosphorylating and uncoupled respiration rates and of ADP/O ratio and by increase of resting respiration. Partial protection of mitochondrial function by POBN suggests that functional damage is related and secondary to superoxide anion production by the mitochondria ''in vitro''.oduction by the mitochondria ''in vitro''.)
Hellgren 2016 Abstract Proceedings of The Physiological Society + (A suboptimal prenatal environment can affe … A suboptimal prenatal environment can affect organogenesis and the natural development of an individual by epigenetic modifications of the genome. While these changes are permanent, it is common not to see any pathological effects until adulthood. The impact of nutritional insults during development has been well-studied in a wide variation of physiological systems. Less studied however, are the effects of hypoxic developmental insults. To this end, our aim is to investigate the long-term effects of prenatal hypoxia on cardiovascular metabolism of adult offspring. We have utilised spectrophotometry to investigate mitochondrial enzyme activity combined with high resolution respirometry to investigate ''in vivo'' mitochondrial efficiency and production of reactive oxygen species. With these methods we aim to identify changes in myocardial mitochondrial energy production, taking a step towards understanding the effect of intrauterine hypoxia on cardiac energetics. Pregnant mice were placed in hypoxic chambers with 14% O2 from gestational day 3-19 and reared in normoxia until six months of age. Heart tissue was harvested and enzymatic activity of citrate synthase and mitochondrial Electron Transport Chain Complexes I-IV was measured using spectrophotometry. High-resolution respirometry lets us further investigate the status of the mitochondria, with emphasis on oxygen consumption and ROS production. Preliminary data show promising differences between treatment and control groups, as well as sexual dimorphism regarding response and effect. We hope to be able to identify possible mechanistic changes, on a cellular level, that underlie the pathological cardiovascular phenotype associated with intrauterine hypoxia.scular phenotype associated with intrauterine hypoxia.)
Petrus 2015 Can J Physiol Pharmacol + (A substantial body of evidence indicates t … A substantial body of evidence indicates that pharmacological activation of mitochondrial ATP-sensitive potassium channels (mKATP) in the heart is protective in conditions associated with ischemia/reperfusion injury. Several mechanisms have been postulated to be responsible for cardioprotection, including the modulation of mitochondrial respiratory function. The aim of the present study was to characterize the dose-dependent effects of novel synthetic benzopyran analogues, derived from a BMS-191095, a selective mKATP opener, on mitochondrial respiration and reactive oxygen species (ROS) production in isolated rat heart mitochondria. Mitochondrial respiratory function was assessed by high-resolution respirometry, and H2O2 production was measured by the Amplex Red fluorescence assay. Four compounds, namely KL-1487, KL-1492, KL-1495, and KL-1507, applied in increasing concentrations (50, 75, 100, and 150 μmol/L, respectively) were investigated. When added in the last two concentrations, all compounds significantly increased State 2 and 4 respiratory rates, an effect that was not abolished by 5-hydroxydecanoate (5-HD, 100 μmol/L), the classic mKATP inhibitor. The highest concentration also elicited an important decrease of the oxidative phosphorylation in a K(+) independent manner. Both concentrations of 100 and 150 μmol/L for KL-1487, KL-1492, and KL-1495, and the concentration of 150 μmol/L for KL-1507, respectively, mitigated the mitochondrial H2O2 release. In isolated rat heart mitochondria, the novel benzopyran analogues act as protonophoric uncouplers of oxidative phosphorylation and decrease the generation of reactive oxygen species in a dose-dependent manner.ylation and decrease the generation of reactive oxygen species in a dose-dependent manner.)
Gnaiger 2011 Abstract-Berlin + (A tight relationship is described between … A tight relationship is described between mitochondrial respiratory capacity of human skeletal muscle and physical fitness, which quantifies the decline of respiratory function as the result of a sedentary life style in the progression towards obesity [1]. Tissue-OXPHOS capacity is the capacity of oxidative phosphorylation in skeletal muscle, which is the product of mitochondrial density and respiratory intensity (structure times function; i.e. mitochondrial marker per tissue mass times OXPHOS capacity per mitochondrial marker). Tissue-OXPHOS capacity per unit wet weight [pmol O2∙s-1∙mg-1] is measured directly in permeabilized muscle fibres, and high-resolution respirometry provides a routine approach under physiological conditions (37 °C; Complex I+II substrate combination) with minimal amounts of tissue biopsy (1 to 3 mg wet weight per assay) [2].In healthy subjects varying from athletic to sedentary life styles, tissue-OXPHOS capacity of vastus lateralis increases linearly with maximum aerobic ergometric performance (''V''O2max) and declines steeply with body mass index (BMI=body mass per body height squared [kg/m2]) in the range of 180 to 60 pmol O2∙s-1∙mg-1. The tissue-OXPHOS/BMI relationship spans from endurance athletes and physically active subjects (normal BMI 20-25), overweight individuals (BMI 25-30) with predominantly sedentary life style, to obese patients who are qualified as healthy controls in studies of type 2 diabetes (BMI >30). Total muscle tissue is unchanged or increases rather than decreases with higher BMI, whereas over-proportionally reduced mitochondrial density per muscle mass explains the loss of aerobic ergometric performance in the sedentary life style and development of obesity. Mitochondrial quality (OXPHOS capacity per mitochondrial marker) is largely maintained, but fatty acid oxidation capacity and coupling control decline as a result of diminishing exercise [2]. Specific mitochondrial injuries accumulate as a consequence of reduced mitochondrial density and correspondingly low mitochondrial turnover. Based on the tissue-OXPHOS/BMI relationship and integrating known mechanisms responsible for dysregulation of mitochondrial biosynthesis under conditions of chronic low-grade inflammation, low mitochondrial density is a primary risk factor related to a wide range of degenerative diseases, including type 2 diabetes. The health benefits are emphasized of maintaining muscle mitochondrial density high, particularly with progressive age, as achieved by a physically active and nutritionally normal life style. The diagnostic perspective gained from analysis of mitochondrial competence after exercise training2 challenges the definition of the control group [3]: Are sedentary subjects healthy? Contribution to K-Regio ''[[MitoCom_O2k-Fluorometer|MitoCom Tyrol]]''.1. [[Gnaiger 2009 Int J Biochem Cell Biol|Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int. J. Biochem. Cell Biol. 41: 1837–1845.]]2. [[Pesta_2011_AJP|Pesta D, Hoppel F, Macek C, Messner H, Faulhaber M, Kobel C, Parson W, Burtscher M, Schocke M, Gnaiger E (2011) Similar qualitative and quantitative changes of mitochondrial respiration following strength and endurance training in normoxia and hypoxia in sedentary humans. Am. J. Physiol. Regul. Integr. Comp. Physiol. doi: 10.1152/ajpregu.00285.2011]]3. Martin B, Ji S, Maudsley S, Mattson MP (2010) "Control" laboratory rodents are metabolically morbid: why it matters. Proc. Natl. Acad. Sci. USA 107: 6127-6133.ttson MP (2010) "Control" laboratory rodents are metabolically morbid: why it matters. Proc. Natl. Acad. Sci. USA 107: 6127-6133.)
Gnaiger 2016 Abstract Mito Xmas Meeting Innsbruck + (A variety of lifestyles developed in human … A variety of lifestyles developed in human populations to cope with the environmental and socioeconomic conditions in the inhabited areas of our world. Extremes at high altitude and latitude impose stress conditions which require adjustments in physiological performance or limit permanent settlements. Modern strength and endurance training regimes may be closely linked to a variety of traditional life styles. Diversity is nature’s treasure and the subject of comparative physiology [1].The Polar Inuit of Thule and Qaarnaak in Greenland are among the northernmost populations. This human heritage of a culture and physiological type is endangered not only by a historical politically forced limitation of their territory, but by the current effects of global environmental pollution and climate change, causing social destabilization and a shift towards an unhealthy sedentary in contrast to the traditional active life style of Inuit hunters. The uncoupling hypothesis for mitochondrial haplogroups of arctic populations suggests that lower coupling of mitochondrial respiration to ATP production was selected for in favour of higher heat dissipation as an adaptation to cold climates through a higher mitochondrial proton leak [2]. Our studies show that mitochondrial coupling control in skeletal muscle of Inuit haplogroups is identical to Danes from western Europe haplogroups, such that biochemical coupling efficiency was preserved across variations in muscle fibre type and lifestyle [3]. Unexpectedly, total capacity of oxidative phosphorylation (OXPHOS) in the leg of the Inuit hunters was lower compared to untrained Danes. In line with this apparent ‘mitochondrial paradox’, total OXPHOS capacity decreased in the Danes during 42 days of active skiing on the sea ice in northern Greenland. The Inuit had a higher capacity to oxidize fat substrate in skeletal muscle which increased in Danes approaching the level of the Inuit. A common pattern emerges of mitochondrial acclimatization and evolutionary adaptation in humans at high latitude and high altitude [3-4]: In these environments, economy of locomotion is optimized by preservation of biochemical coupling efficiency at modest mitochondrial density, when ''V''O2max and sustained submaximum performance are not dependent on peripherally increased capacities of oxidative phosphorylation.lly increased capacities of oxidative phosphorylation.)
Maddalena 2017 Biochim Biophys Acta + (A variety of mitochondria-targeted small m … A variety of mitochondria-targeted small molecules have been invented to manipulate mitochondrial redox activities and improve function in certain disease states. 3-Hydroxypropyl-triphenylphosphonium-conjugated imidazole-substituted oleic acid (TPP-IOA) was developed as a specific inhibitor of cytochrome c peroxidase activity that inhibits apoptosis by preventing cardiolipin oxidation and cytochrome c release to the cytosol. Here we evaluate the effects of TPP-IOA on oxidative phosphorylation in isolated mitochondria and on mitochondrial function in live cells. We demonstrate that, at concentrations similar to those required to achieve inhibition of cytochrome c peroxidase activity, TPP-IOA perturbs oxidative phosphorylation in isolated mitochondria. In live SH-SY5Y cells, TPP-IOA partially collapsed mitochondrial membrane potential, caused extensive fragmentation of the mitochondrial network, and decreased apparent mitochondrial abundance within 3h of exposure. Many cultured cell lines rely primarily on aerobic glycolysis, potentially making them less sensitive to small molecules disrupting oxidative phosphorylation. We therefore determined the anti-apoptotic efficacy of TPP-IOA in SH-SY5Y cells growing in glucose or in galactose, the latter of which increases reliance on oxidative phosphorylation for ATP supply. The anti-apoptotic activity of TPP-IOA that was observed in glucose media was not seen in galactose media. It therefore appears that, at concentrations required to inhibit cytochrome c peroxidase activity, TPP-IOA perturbs oxidative phosphorylation. In light of these data it is predicted that potential future therapeutic applications of TPP-IOA will be restricted to highly glycolytic cell types with limited reliance on oxidative phosphorylation.Copyright © 2016 Elsevier B.V. All rights reserved. © 2016 Elsevier B.V. All rights reserved.)
Mould 2023 Front Physiol + (A wide variety of studies have reported so … A wide variety of studies have reported some form of non-chemical or non-aqueous communication between physically isolated organisms, eliciting changes in cellular proliferation, morphology, and/or metabolism. The sources and mechanisms of such signalling pathways are still unknown, but have been postulated to involve vibration, volatile transmission, or light through the phenomenon of ultraweak photon emission. Here, we report non-chemical communication between isolated mitochondria from MCF7 (cancer) and MCF10A (non-cancer) cell lines. We found that mitochondria in one cuvette stressed by an electron transport chain inhibitor, antimycin, alters the respiration of mitochondria in an adjacent, but chemically and physically separate cuvette, significantly decreasing the rate of oxygen consumption compared to a control (p = <0.0001 in MCF7 and MCF10A mitochondria). Moreover, the changes in O2-consumption were dependent on the origin of mitochondria (cancer vs. non-cancer) as well as the presence of "ambient" light. Our results support the existence of non-chemical signalling between isolated mitochondria. The experimental design suggests that the non-chemical communication is light-based, although further work is needed to fully elucidate its nature.work is needed to fully elucidate its nature.)
Li 2020 G3 (Bethesda) + (A yeast deletion mutation in the nuclear-e … A yeast deletion mutation in the nuclear-encoded gene, AFO1, which codes for a mitochondrial ribosomal protein, led to slow growth on glucose, the inability to grow on glycerol or ethanol, and loss of mitochondrial DNA and respiration. We noticed that afo1- yeast readily obtains secondary mutations that suppress aspects of this phenotype, including its growth defect. We characterized and identified a dominant missense suppressor mutation in the ATP3 gene. Comparing isogenic slowly growing rho-zero and rapidly growing suppressed afo1- strains under carefully controlled fermentation conditions showed that energy charge was not significantly different between strains and was not causal for the observed growth properties. Surprisingly, in a wild-type background, the dominant suppressor allele of ATP3 still allowed respiratory growth but increased the petite frequency. Similarly, a slow-growing respiratory deficient afo1- strain displayed an about twofold increase in spontaneous frequency of point mutations (comparable to the rho-zero strain) while the suppressed strain showed mutation frequency comparable to the repiratory-competent WT strain. We conclude, that phenotypes that result from afo1- are mostly explained by rapidly emerging mutations that compensate for the slow growth that typically follows respiratory deficiency.tations that compensate for the slow growth that typically follows respiratory deficiency.)
Papadimitriou 2018 Thesis + (ACTN3 has been labelled as the ‘gene for s … ACTN3 has been labelled as the ‘gene for speed’ due to the increased frequency of the R allele encoding the α-actinin-3 protein in elite sprint athletes compared to the general population. The results of the first study of this thesis demonstrate that elite athletes who express α-actinin-3 (ACTN3 RR genotype) have faster sprint times compared to those who do not express α-actinin-3 (ACTN3 XX genotype). Further analysis indicates that the ACTN3 genotype accounts for 0.92% in sprint speed amongst elite 200-m athletes. In study two, the same quantitative genetic epidemiological design applied to elite endurance athletes, showed no evidence that a trade-off existed. The endurance athletes with the ACTN3 XX genotype were no faster than those who express the α-actinin-3 protein. These results added to literature that it is unlikely the ACTN3 XX genotype to offer an advantage for endurance performance. While ACTN3 genotype does not appear to influence endurance performance in athletes, studies in mice that completely lack the α-actinin-3 protein suggest the ACTN3 genotype influences the adaptive response to endurance exercise. Based on these findings, the aim of study 3 was to investigate if ACTN3 genotype influences exercise-induced changes in the content of genes and proteins associated with mitochondrial biogenesis. At baseline, there was a compensatory greater α-actinin-2 protein content in ACTN3 XX vs ACTN3 RR participants (p=0.018) but there were no differences in the endurance-related phenotypes measured. There was a main effect of genotype (p=0.006), without a significant interaction effect, for RCAN1-4 or significant exercise-induced expression of genes associated with mitochondrial biogenesis. Together, these results suggest that ACTN3 genotype has a small but significant influence on sprint speed amongst elite sprint athletes. However, loss of α-actinin-3 protein is not associated with higher values for endurance-related phenotypes, endurance performance, or a greater adaptive response to a single session of high-intensity endurance exercise.sion of high-intensity endurance exercise.)
Kotiadis 2012 J Cell Sci + (ADF/cofilin family proteins are essential … ADF/cofilin family proteins are essential regulators of actin cytoskeletal dynamics. Recent evidence also implicates cofilin in the regulation of mitochondrial function. Here, we identify new functional surfaces of cofilin that are linked with mitochondrial function and stress responses in the budding yeast ''S. cerevisiae''. Our data links surfaces of cofilin that are involved in separable activities of actin filament disassembly or stabilisation, to the regulation of mitochondrial morphology and the activation status of Ras respectively. Importantly, charge alterations to conserved surfaces of cofilin that do not interfere with its actin regulatory activity leads to a dramatic increase in respiratory function that triggers a retrograde signal to up-regulate a battery of ABC transporters and concurrent metabolic changes that support multi-drug resistance. We hypothesise that cofilin functions within a novel bio-sensing system that connects the cytoskeleton and mitochondrial function to environmental challenge.drial function to environmental challenge.)
Scheibye-Knudsen 2009 Eur J Appl Physiol + (ADP is generally accepted as a key regulat … ADP is generally accepted as a key regulator of oxygen consumption both in isolated mitochondria and in permeabilized fibers from skeletal muscle. The present study explored inorganic phosphate in a similar regulatory role. Saponin permeabilized fibers and isolated mitochondria from type-I and type-II muscle from male Wistar rats were prepared. Respiration was measured while the medium Pi concentration was gradually increased. The apparent Km values for Pi were 607 ± 17 µM and 405 ± 15 μM (P < 0.0001) for type-I and type-II fibers, respectively. For isolated mitochondria the values were significantly lower than type-1 permeabilized fibers, 338 ± 130 μM and 235 ± 30 μM (P < 0.05), but not different with respect to fiber type. The reason for this difference in Km values in the permeabilized muscle is unknown, but a similar pattern has been observed for K m of ADP. Our data indicate that phosphate may play a role in regulation of oxygen consumption ''in vitro'' and ''in vivo''.oxygen consumption ''in vitro'' and ''in vivo''.)
Ara 2011 Int J Obes + (AIM/HYPOTHESIS: The aim of this study was … AIM/HYPOTHESIS: The aim of this study was to investigate mitochondrial function, fibre-type distribution and substrate oxidation during exercise in arm and leg muscles in male postobese (PO), obese (O) and age- and body mass index (BMI)-matched control (C) subjects. The hypothesis of the study was that fat oxidation during exercise might be differentially preserved in leg and arm muscles after weight loss.METHODS: Indirect calorimetry was used to calculate fat and carbohydrate oxidation during both progressive arm-cranking and leg-cycling exercises. Muscle biopsy samples were obtained from musculus deltoideus (m. deltoideus) and m. vastus lateralis muscles. Fibre-type composition, enzyme activity and O2 flux capacity of saponin-permeabilized muscle fibres were measured, the latter by high-resolution respirometry.RESULTS: During the graded exercise tests, peak fat oxidation during leg cycling and the relative workload at which it occurred (FatMax) were higher in PO and O than in C. During arm cranking, peak fat oxidation was higher in O than in C, and FatMax was higher in O than in PO and C. Similar fibre-type composition was found between groups. Plasma adiponectin was higher in PO than in C and O, and plasma leptin was higher in O than in PO and C.CONCLUSIONS: In O subjects, maximal fat oxidation during exercise and the eliciting relative exercise intensity are increased. This is associated with higher intramuscular triglyceride levels and higher resting non esterified fatty acid (NEFA) concentrations, but not with differences in fibre-type composition, mitochondrial function or muscle enzyme levels compared with Cs. In PO subjects, the changes in fat oxidation are preserved during leg, but not during arm, exercise. during leg, but not during arm, exercise.)
Nakhostin-Roohi 2008 J Sports Med Phys Fitness + (AIM: Low levels of physical activity and c … AIM:Low levels of physical activity and cardio respiratory fitness are both associated with higher risk of all-cause and disease-specific mortality. The purpose of this study is to examine obesity and fitness of the female staff of Ardebil Azad University in the northwest of Iran.METHODS:Thirty seven staff (medium age: 32.97+/-5.81 year, height: 158.21+/-5.88 cm, Body Mass Index [BMI]: 26.59+/-4.02 kg/m(2)) of Ardebil Azad University participated in this study voluntarily. Primary measurements of interest in the present study were height, BMI, subcutaneous skin folds, and cardio respiratory fitness determined by 1 609 meter (one mile) walk test.RESULTS:The subjects of the present study are more obese than some other population (fat percentage: 28.68+/-5.33) and cardio respiratory fitness of them is rather low (VO(2max): 33.43+/-6.90 mL/kg/min).CONCLUSION:Social/lifestyle factors such as the level of education, marital status, exercise, dietary and smoking habits may be related to overweight/obesity and cardio respiratory fitness in female staff of Ardebil Azad University.n female staff of Ardebil Azad University.)
Larsen 2012 Acta Physiol (Oxf) + (AIM: Mitochondrial function has previously … AIM: Mitochondrial function has previously been studied in ageing, but never in humans matched for maximal oxygen uptake (V·O2max). Furthermore, the influence of ageing on mitochondrial substrate sensitivity is not known.METHODS: Skeletal muscle mitochondrial respiratory capacity and mitochondrial substrate sensitivity was measured by respirometry in young (23±3 years) and middle-aged (53±3 years) male subjects with similar V·O2max. Protocols for respirometry included titration of substrates for complexI (glutamate), complexII (succinate) and both (octanoyl-carnitine) for calculation of substrate sensitivity (C(50) ). Myosin Heavy Chain (MHC) isoforms, citrate synthase (CS) and β-hydroxy-acyl-CoA-dehydrogenase (HAD) activity, mitochondrial DNA (mtDNA) content, protein levels of complexes I-V and antioxidant defense system (manganese superoxide dismutase (MnSOD)) was measured.RESULTS: No differences were found in maximal mitochondrial respiration or C(50) with glutamate (2.0±0.3 and 1.8±0.3 mmol/l), succinate (3.7±0.2 and 3.8±0.4 mmol/l) or octanoyl-carnitine (47±8 and 56±7 μmol/l) in young and middle-aged subjects, respectively. Normalising mitochondrial respiration to mtDNA young subjects had a higher (P<0.05) respiratory capacity per mitochondrion compared to middle-aged subjects. HAD activity and mtDNA per mg tissue were higher in middle-aged compared to young subjects. Middle-aged had a higher MHC I isoform and a lower MHC IIX isoform content compared to young subjects.CONCLUSION: Mitochondrial substrate sensitivity is not affected by ageing. When young and middle-aged men are carefully matched for V·O2max, mitochondrial respiratory capacity is also similar. However, per mitochondrion respiratory capacity was lower in middle-aged compared to young subjects. Thus, when matched for V·O2max middle-aged seems to require a higher mitochondrial content than young subjects.er mitochondrial content than young subjects.)
Raboel 2009 Diabetes Obes Metab + (AIM: Several mechanisms have been targeted … AIM: Several mechanisms have been targeted as culprits of weight gain during antihyperglycaemic treatment in type 2 diabetes (T2DM). These include reductions in glucosuria, increased food intake from fear of hypoglycaemia, the anabolic effect of insulin, decreased metabolic rate and increased efficiency in fuel usage. The purpose of the study was to test the hypothesis that mitochondrial efficiency increases as a result of insulin treatment in patients with type 2 diabetes.METHODS: We included ten patients with T2DM (eight males) on oral antidiabetic treatment, median age: 51.5 years (range: 39-67) and body mass index (BMI): 30.1 +/- 1.2 kg/m2 (mean +/- s.e.). Muscle biopsies from m. vastus lateralis and m. deltoideus were obtained before and after seven weeks of intensive insulin treatment, and mitochondrial respiration was measured using high-resolution respirometry. State 3 respiration was measured with the substrates malate, pyruvate, glutamate, succinate and ADP. State 4o was measured with addition of oligomycine. An age, sex and BMI-matched control group was also included.RESULTS: HbA1c improved significantly and the patients gained on average 3.4 +/- 0.9 kg. Before treatment, respiratory control ratios (RCRs) of the T2DM were lower than the obese controls [2.6 vs. 3.2 (p < 0.05)], but RCR returned to the levels of the control subjects during treatment. Average state 4o of arm and leg declined by 14% (p < 0.05) during insulin treatment.CONCLUSIONS: Tight glycaemic control leads to reductions in inner mitochondrial membrane leak and increased efficiency of mitochondria. This change in mitochondrial physiology could contribute to the weight gain seen with antihyperglycaemic treatment.ght gain seen with antihyperglycaemic treatment.)
Melzer 2010 Ann Nutr Metab + (AIM: The resting metabolic rate (RMR) vari … AIM: The resting metabolic rate (RMR) varies among pregnant women. The factors responsible for this variability are unknown. This study aimed to assess the influence of the prepregnancy body mass index (BMI) on the RMR during late pregnancy.METHODS: RMR, height, weight, and total (TEE) and activity (AEE) energy expenditures were measured in 46 healthy women aged 31 ± 5 years (mean ± SD) with low (<19.8), normal (19.8-26.0), and high (>26.0) prepregnancy BMI at 38.2 ± 1.5 weeks of gestation (t(gest)) and 40 ± 7 weeks postpartum (t(post)) (''n'' = 27).RESULTS: The mean t(gest) RMR for the low-, normal-, and high-BMI groups was 1,373, 1,807, and 2,191 kcal/day, respectively (''p'' = 0.001). The overall mean t(gest) RMR was 316 ± 183 kcal/day (21%), higher than the overall mean t(post) value and this difference was correlated with gestational weight gain (''r'' = 0.78, ''p'' < 0.001). The scaled metabolic rate by allometry (RMR/kilograms⁰·⁷³) was similar in the low-, normal-, and high-BMI groups, respectively (''p'' = 0.45). Changes in t(gest) TEE closely paralleled changes in t(gest) RMR (''r'' = 0.84, 'p'' < 0.001). AEE was similar among the BMI groups.CONCLUSION: The RMR is significantly increased in the third trimester of pregnancy. The absolute gestational RMR is higher in women with high prepregnancy BMI due to increased body weight. The scaled metabolic rate (RMR/kilograms⁰·⁷³) is similar among the BMI groups of pregnant women.⁷³) is similar among the BMI groups of pregnant women.)
WHO 2006 Acta Paediatr + (AIM: To describe the methods used to const … AIM: To describe the methods used to construct the WHO Child Growth Standards based on length/height, weight and age, and to present resulting growth charts.METHODS: The WHO Child Growth Standards were derived from an international sample of healthy breastfed infants and young children raised in environments that do not constrain growth. Rigorous methods of data collection and standardized procedures across study sites yielded very high-quality data. The generation of the standards followed methodical, state-of-the-art statistical methodologies. The Box-Cox power exponential (BCPE) method, with curve smoothing by cubic splines, was used to construct the curves. The BCPE accommodates various kinds of distributions, from normal to skewed or kurtotic, as necessary. A set of diagnostic tools was used to detect possible biases in estimated percentiles or z-score curves.RESULTS: There was wide variability in the degrees of freedom required for the cubic splines to achieve the best model. Except for length/height-for-age, which followed a normal distribution, all other standards needed to model skewness but not kurtosis. Length-for-age and height-for-age standards were constructed by fitting a unique model that reflected the 0.7-cm average difference between these two measurements. The concordance between smoothed percentile curves and empirical percentiles was excellent and free of bias. Percentiles and z-score curves for boys and girls aged 0-60 mo were generated for weight-for-age, length/height-for-age, weight-for-length/height (45 to 110 cm and 65 to 120 cm, respectively) and body mass index-for-age.CONCLUSION: The WHO Child Growth Standards depict normal growth under optimal environmental conditions and can be used to assess children everywhere, regardless of ethnicity, socio-economic status and type of feeding.socio-economic status and type of feeding.)
Larsen 2011 Acta Physiol (Oxf) + (AIM: To study whether the phenotypical cha … AIM: To study whether the phenotypical characteristics (exercise intolerance; reduced spontaneous activity) of the AMPKα2 kinase-dead (KD) mice can be explained by a reduced mitochondrial respiratory flux rates (JO(2) ) in skeletal muscle. Secondly, the effect of the maturation process on JO(2) was studied.METHODS: In tibialis anterior (almost exclusively type 2 fibres) muscle from young (12-17 weeks, n = 7) and mature (25-27 weeks, n = 12) KD and wild-type (WT) (12-17 weeks, n = 9; 25-27 weeks, n = 11) littermates, JO(2) was quantified in permeabilized fibres ex vivo by respirometry, using a substrate-uncoupler-inhibitor-titration (SUIT) protocol: malate, octanoyl carnitine, ADP and glutamate (GMO(3) ), + succinate (GMOS(3) ), + uncoupler (U) and inhibitor (rotenone) of complex I respiration. Citrate synthase (CS) activity was measured as an index of mitochondrial content.RESULTS: Citrate synthase activity was highest in young WT animals and lower in KD animals compared with age-matched WT. JO(2) per mg tissue was lower (P < 0.05) in KD animals (state GMOS(3) ). No uncoupling effect was seen in any of the animals. Normalized oxygen flux (JO(2) /CS) revealed a uniform pattern across the SUIT protocol with no effect of KD. However, JO(2) /CS was higher [GMO(3) , GMOS(3) , U and rotenone (only WT)] in the mature compared with the young mice - irrespective of the genotype (P < 0.05).CONCLUSION: Exercise intolerance and reduced activity level seen in KD mice may be explained by reduced JO(2) in the maximally coupled respiratory state. Furthermore, an enhancement of oxidative phosphorylation capacity per mitochondrion is seen with the maturation process.tochondrion is seen with the maturation process.)
Paglialunga 2012 Diabetologia + (AIMS/HYPOTHESIS: High-fat, high-sucrose d … AIMS/HYPOTHESIS: High-fat, high-sucrose diet (HF)-induced reactive oxygen species (ROS) levels are implicated in skeletal muscle insulin resistance and mitochondrial dysfunction. Here we investigated whether mitochondrial ROS sequestering can circumvent HF-induced oxidative stress; we also determined the impact of any reduced oxidative stress on muscle insulin sensitivity and mitochondrial function.METHODS: The Skulachev ion (plastoquinonyl decyltriphenylphosphonium) (SkQ), a mitochondria-specific antioxidant, was used to target ROS production in C2C12 muscle cells as well as in HF-fed (16 weeks old) male C57Bl/6 mice, compared with mice on low-fat chow diet (LF) or HF alone. Oxidative stress was measured as protein carbonylation levels. Glucose tolerance tests, glucose uptake assays and insulin-stimulated signalling were determined to assess muscle insulin sensitivity. Mitochondrial function was determined by high-resolution respirometry.RESULTS: SkQ treatment reduced oxidative stress in muscle cells (-23% p < 0.05), but did not improve insulin sensitivity and glucose uptake under insulin-resistant conditions. In HF mice, oxidative stress was elevated (56% vs LF p < 0.05), an effect completely blunted by SkQ. However, HF and HF+SkQ mice displayed impaired glucose tolerance (AUC HF up 33%, p < 0.001; HF+SkQ up 22%; p < 0.01 vs LF) and disrupted skeletal muscle insulin signalling. ROS sequestering did not improve mitochondrial function.CONCLUSIONS/INTERPRETATION:SkQ treatment reduced muscle mitochondrial ROS production and prevented HF-induced oxidative stress. Nonetheless, whole-body glucose tolerance, insulin-stimulated glucose uptake, muscle insulin signalling and mitochondrial function were not improved. These results suggest that HF-induced oxidative stress is not a prerequisite for the development of muscle insulin resistance.site for the development of muscle insulin resistance.)
Friederich-Persson 2012 Diabetologia + (AIMS/HYPOTHESIS: Increased oxygen consump … AIMS/HYPOTHESIS: Increased oxygen consumption results in kidney tissue hypoxia, which is proposed to contribute to the development of diabetic nephropathy. Oxidative stress causes increased oxygen consumption in type 1 diabetic kidneys, partly mediated by uncoupling protein-2 (UCP-2)-induced mitochondrial uncoupling. The present study investigates the role of UCP-2 and oxidative stress in mitochondrial oxygen consumption and kidney function in db/db mice as a model of type 2 diabetes.METHODS: Mitochondrial oxygen consumption, glomerular filtration rate and proteinuria were investigated in db/db mice and corresponding controls with and without coenzyme Q10 (CoQ10) treatment.RESULTS: Untreated db/db mice displayed mitochondrial uncoupling, manifested as glutamate-stimulated oxygen consumption (2.7 ± 0.1 vs 0.2 ± 0.1 pmol O(2) s(-1) [mg protein](-1)), glomerular hyperfiltration (502 ± 26 vs 385 ± 3 μl/min), increased proteinuria (21 ± 2 vs 14 ± 1, μg/24 h), mitochondrial fragmentation (fragmentation score 2.4 ± 0.3 vs 0.7 ± 0.1) and size (1.6 ± 0.1 vs 1 ± 0.0 μm) compared with untreated controls. All alterations were prevented or reduced by CoQ10 treatment. Mitochondrial uncoupling was partly inhibited by the UCP inhibitor GDP (-1.1 ± 0.1 pmol O(2) s(-1) [mg protein](-1)). UCP-2 protein levels were similar in untreated control and db/db mice (67 ± 9 vs 67 ± 4 optical density; OD) but were reduced in CoQ10 treated groups (43 ± 2 and 38 ± 7 OD).CONCLUSIONS/INTERPRETATION: db/db mice displayed oxidative stress-mediated activation of UCP-2, which resulted in mitochondrial uncoupling and increased oxygen consumption. CoQ10 prevented altered mitochondrial function and morphology, glomerular hyperfiltration and proteinuria in db/db mice, highlighting the role of mitochondria in the pathogenesis of diabetic nephropathy and the benefits of preventing increased oxidative stress. of preventing increased oxidative stress.)
Flachs 2011 Diabetologia + (AIMS/HYPOTHESIS: Calorie restriction is an … AIMS/HYPOTHESIS: Calorie restriction is an essential component in the treatment of obesity and associated diseases. Long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) act as natural hypolipidaemics, reduce the risk of cardiovascular disease and could prevent the development of obesity and insulin resistance. We aimed to characterise the effectiveness and underlying mechanisms of the combination treatment with LC n-3 PUFA and 10% calorie restriction in the prevention of obesity and associated disorders in mice.METHODS: Male mice (C57BL/6J) were habituated to a corn-oil-based high-fat diet (cHF) for 2 weeks and then randomly assigned to various dietary treatments for 5 weeks or 15 weeks: (1) cHF, ad libitum; (2) cHF with LC n-3 PUFA concentrate replacing 15% (wt/wt) of dietary lipids (cHF + F), ad libitum; (3) cHF with calorie restriction (CR; cHF + CR); and (4) cHF + F + CR. Mice fed a chow diet were also studied. RESULTS: We show that white adipose tissue plays an active role in the amelioration of obesity and the improvement of glucose homeostasis by combining LC n-3 PUFA intake and calorie restriction in cHF-fed mice. Specifically in the epididymal fat in the abdomen, but not in other fat depots, synergistic induction of mitochondrial oxidative capacity and lipid catabolism was observed, resulting in increased oxidation of metabolic fuels in the absence of mitochondrial uncoupling, while low-grade inflammation was suppressed, reflecting changes in tissue levels of anti-inflammatory lipid mediators, namely 15-deoxy-Δ(12,15)-prostaglandin J(2) and protectin D1.CONCLUSIONS/INTERPRETATION: White adipose tissue metabolism linked to its inflammatory status in obesity could be modulated by combination treatment using calorie restriction and dietary LC n-3 PUFA to improve therapeutic strategies for metabolic syndrome.apeutic strategies for metabolic syndrome.)
Rosca 2008 Cardiovasc Res + (AIMS: Mitochondrial dysfunction is a maj … AIMS: Mitochondrial dysfunction is a major factor in heart failure (HF). A pronounced variability of mitochondrial electron transport chain (ETC) defects is reported to occur in severe acquired cardiomyopathies without a consistent trend for depressed activity or expression. The aim of this study was to define the defect in the integrative function of cardiac mitochondria in coronary microembolization-induced HF.METHODS AND RESULTS:Studies were performed in the canine coronary microembolization-induced HF model of moderate severity. Oxidative phosphorylation was assessed as the integrative function of mitochondria, using a comprehensive variety of substrates in order to investigate mitochondrial membrane transport, dehydrogenase activity and electron-transport coupled to ATP synthesis. The supramolecular organization of the mitochondrial ETC also was investigated by native gel electrophoresis. We found a dramatic decrease in ADP-stimulated respiration that was not relieved by an uncoupler. Moreover, the ADP/O ratio was normal, indicating no defect in the phosphorylation apparatus. The data point to a defect in oxidative phosphorylation within the ETC. However, the individual activities of ETC complexes were normal. The amount of the supercomplex consisting of complex I/complex III dimer/complex IV, the major form of respirasome considered essential for oxidative phosphorylation, was decreased.CONCLUSIONS:We propose that the mitochondrial defect lies in the supermolecular assembly rather than in the individual components of the ETC.n in the individual components of the ETC.)
Wen 2017 Antioxid Redox Signal + (AIMS: We investigated the effects of mit … AIMS: We investigated the effects of mitochondrial reactive oxygen species (mtROS) on nuclear factor (erythroid 2)-like 2 (NFE2L2) transcription factor activity during Trypanosoma cruzi (Tc) infection and determined whether enhancing the mtROS scavenging capacity preserved the heart function in Chagas disease.RESULTS: C57BL/6 wild type (WT, female) mice infected with Tc exhibited myocardial loss of mitochondrial membrane potential, complex II (CII)-driven coupled respiration, and ninefold increase in mtROS production. In vitro and in vivo studies showed that Tc infection resulted in an ROS-dependent decline in the expression, nuclear translocation, antioxidant response element (ARE) binding, and activity of NFE2L2, and 35-99% decline in antioxidants' (gamma-glutamyl cysteine synthase [γGCS], heme oxygenase-1 [HO1], glutamate-cysteine ligase modifier subunit [GCLM], thioredoxin (Trx), glutathione S transferase [GST], and NAD(P)H dehydrogenase, quinone 1 [NQO1]) expression. An increase in myocardial and mitochondrial oxidative adducts, myocardial interventricular septum thickness, and left ventricle (LV) mass, a decline in LV posterior wall thickness, and disproportionate synthesis of collagens (COLI/COLIII), αSMA, and SM22α were noted in WT.Tc mice. Overexpression of manganese superoxide dismutase (MnSOD) in cultured cells (HeLa or cardiomyocytes) and MnSODtg mice preserved the NFE2L2 transcriptional activity and antioxidant/oxidant balance, and cardiac oxidative and fibrotic pathology were significantly decreased in MnSODtg.Tc mice. Importantly, echocardiography finding of a decline in LV systolic (stroke volume, cardiac output, ejection fraction) and diastolic (early/late peak filling ratio, myocardial performance index) function in WT. Tc mice was abolished in MnSODtg. Tc mice. Innovation and Conclusion: The mtROS inhibition of NFE2L2/ARE pathway constitutes a key mechanism in signaling the fibrotic gene expression and evolution of chronic cardiomyopathy. Preserving the NFE2L2 activity arrested the mitochondrial and cardiac oxidative stress, cardiac fibrosis, and heart failure in Chagas disease.osis, and heart failure in Chagas disease.)
Meinild Lundby 2018 Acta Physiol (Oxf) + (AIMS: 1) determine whether exercise induce … AIMS: 1) determine whether exercise induced increases in muscle mitochondrial volume density (MitoVD ) is related to enlargement of existing mitochondria or de novo biogenesis, 2) establish if measures of mitochondrial-specific enzymatic activities are valid biomarkers for exercise induced increases in MitoVD .METHOD: Skeletal muscle samples were collected from twenty-one healthy males prior to and following 6 weeks of endurance training. Transmission electron microscopy was used for estimation of mitochondrial densities and profiles. Biochemical assays, western blotting and high resolution respirometry were applied to detect changes in specific mitochondrial functions.RESULT: MitoVD increased with 55 ± 9% (''P'' < 0.001), whereas the number of mitochondrial profiles per area of skeletal muscle remained unchanged following training. Citrate synthase activity (CS) increased (44 ± 12%, ''P'' < 0.001) however, there were no functional changes in oxidative phosphorylation capacity (OXPHOS, CI+IIP ) or cytochrome c oxidase (COX) activity. Correlations were found between MitoVD and CS (''P''=0.01; ''r''=0.58), OXPHOS, CI+CIIP (''P''=0.01; ''r''=0.58) and COX (''P''=0.02; ''r''=0.52) before training, after training a correlation was found between MitoVD and CS activity only (''P''=0.04; ''r''=0.49). Intrinsic respiratory capacities decreased (''P'' < 0.05) with training when respiration was normalized to MitoVD. This was not the case when normalized to CS activity although the percentage change was comparable. CONCLUSIONS: MitoVD was increased by inducing mitochondrial enlargement rather than de novo biogenesis. CS activity may be appropriate to track training induced changes in MitoVD.priate to track training induced changes in MitoVD.)
Hafstad 2011 J Appl Physiol + (AIMS: Although exercise training induces h … AIMS: Although exercise training induces hypertrophy with improved contractile function, the effect of exercise on myocardial substrate metabolism and cardiac efficiency is less clear. High intensity training has been shown to produce more profound effects on cardiovascular function and aerobic capacity than isocaloric low and moderate intensity training. The aim of the present study was to explore metabolic and mechanoenergetic changes in the heart following endurance exercise training of both high and moderate intensity.METHODS AND RESULTS: C57BL/6J mice were subjected to 10 wk treadmill running, either high intensity interval training (HIT) or distance-matched moderate intensity training (MIT), where HIT led to a pronounced increase in maximal oxygen uptake. Although both modes of exercise were associated with a 10% increase in heart weight-to-body weight ratio, only HIT altered cardiac substrate utilization, as revealed by a 36% increase in glucose oxidation and a concomitant reduction in fatty acid oxidation. HIT also improved cardiac efficiency by decreasing work-independent myocardial oxygen consumption. In addition, it increased cardiac maximal mitochondrial respiratory capacity.CONCLUSION: This study shows that high intensity training is required for induction of changes in cardiac substrate utilization and energetics, which may contribute to the superior effects of high compared with moderate intensity training in terms of increasing aerobic capacity.g in terms of increasing aerobic capacity.)
Bouitbir 2016 Antioxid Redox Signal + (AIMS: Although statins are the most widely … AIMS: Although statins are the most widely used cholesterol-lowering agents, they are associated with a variety of muscle complaints. The goal of this study was to characterize the effects of statins on the mitochondrial apoptosis pathway induced by mitochondrial oxidative stress in skeletal muscle using human muscle biopsies as well as ''in vivo'' and ''in vitro'' models.RESULTS:Statins increased mitochondrial H2O2 production, the Bax/Bcl-2 ratio and TUNEL staining in deltoid biopsies of patients with statin-associated myopathy. Furthermore, atorvastatin treatment for two weeks at 10 mg/kg/day in rats increased H2O2 accumulation, and mRNA levels and immunostaining of the Bax/Bcl-2 ratio, as well as TUNEL staining and caspase 3 cleavage in glycolytic (plantaris) skeletal muscle but not in oxidative (soleus) skeletal muscle, which has a high antioxidative capacity. Atorvastatin also decreased the GSH/GSSG ratio, but only in glycolytic skeletal muscle. Co-treatment with the antioxidant quercetin at 25 mg/kg/d abolished these effects in plantaris. An ''in vitro'' study with L6 myoblasts directly demonstrated the link between mitochondrial oxidative stress following atorvastatin exposure and activation of the mitochondrial apoptosis signaling pathway.INNOVATION:Treatment with atorvastatin is associated with mitochondrial oxidative stress, which activates apoptosis and contributes to myopathy. Glycolytic muscles are more sensitive to atorvastatin than oxidative muscles, which may be due to the higher antioxidative capacity in oxidative muscles.CONCLUSION:There is a link between statin-induced mitochondrial oxidative stress and activation of the mitochondrial apoptosis signaling pathway in glycolytic skeletal muscle, which may be associated with statin-associated myopathy.ay in glycolytic skeletal muscle, which may be associated with statin-associated myopathy.)
Lancel 2012 PLoS One + (AIMS: Metabolic syndrome induces cardiac d … AIMS: Metabolic syndrome induces cardiac dysfunction associated with mitochondria abnormalities. As low levels of carbon monoxide (CO) may improve myocardial and mitochondrial activities, we tested whether a CO-releasing molecule (CORM-3) reverses metabolic syndrome-induced cardiac alteration through changes in mitochondrial biogenesis, dynamics and autophagy. METHODS AND RESULTS: Mice were fed with normal diet (ND) or high-fat diet (HFD) for twelve weeks. Then, mice received two intraperitoneal injections of CORM-3 (10 mg x kg(-1)), with the second one given 16 hours after the first. Contractile function in isolated hearts and mitochondrial parameters were evaluated 24 hours after the last injection. Mitochondrial population was explored by electron microscopy. Changes in mitochondrial dynamics, biogenesis and autophagy were assessed by western-blot and RT-qPCR. Left ventricular developed pressure was reduced in HFD hearts. Mitochondria from HFD hearts presented reduced membrane potential and diminished ADP-coupled respiration. CORM-3 restored both cardiac and mitochondrial functions. Size and number of mitochondria increased in the HFD hearts but not in the CORM-3-treated HFD group. CORM-3 modulated HFD-activated mitochondrial fusion and biogenesis signalling. While autophagy was not activated in the HFD group, CORM-3 increased the autophagy marker LC3-II. Finally, ''ex vivo'' experiments demonstrated that autophagy inhibition by 3-methyladenine abolished the cardioprotective effects of CORM-3. CONCLUSION: CORM-3 may modulate pathways controlling mitochondrial quality, thus leading to improvements of mitochondrial efficiency and HFD-induced cardiac dysfunction.iency and HFD-induced cardiac dysfunction.)
Haram 2009 Cardiovasc Res + (AIMS: The recent development of a rat mode … AIMS: The recent development of a rat model that closely resembles the metabolic syndrome allows to study the mechanisms of amelioration of the syndrome by exercise training. Here, we compared the effectiveness for reducing cardiovascular risk factors by exercise training programmes of different exercise intensities.METHODS AND RESULTS: Metabolic syndrome rats were subjected to either continuous moderate-intensity exercise (CME) or high-intensity aerobic interval training (AIT). AIT was more effective than CME at reducing cardiovascular disease risk factors linked to the metabolic syndrome. Thus, AIT produced a larger stimulus than CME for increasing maximal oxygen uptake (VO2max; 45 vs. 10%, ''P'' < 0.01), reducing hypertension (20 vs. 6 mmHg, ''P'' < 0.01), HDL cholesterol (25 vs. 0%, ''P'' < 0.05), and beneficially altering metabolism in fat, liver, and skeletal muscle tissues. Moreover, AIT had a greater beneficial effect than CME on sensitivity of aorta ring segments to acetylcholine (2.7- vs. 2.0-fold, ''P'' < 0.01), partly because of intensity-dependent effects on expression levels of nitric oxide synthase and the density of caveolae, and a greater effect than CME on the skeletal muscle Ca2+ handling (50 vs. 0%, ''P'' < 0.05). The two exercise training programmes, however, were equally effective at reducing body weight and fat content.CONCLUSION: High-intensity exercise training was more beneficial than moderate-intensity exercise training for reducing cardiovascular risk in rats with the metabolic syndrome. This was linked to more superior effects on VO2max, endothelial function, blood pressure, and metabolic parameters in several tissues. These results demonstrate that exercise training reduces the impact of the metabolic syndrome and that the magnitude of the effect depends on exercise intensity.of the metabolic syndrome and that the magnitude of the effect depends on exercise intensity.)
Garcia-Roves 2008 J Biol Chem + (AMP-activated protein kinase (AMPK) is a h … AMP-activated protein kinase (AMPK) is a heterotrimeric complex, composed of a catalytic subunit (α) and two regulatory subunits (β and γ), that works as a cellular energy sensor. The existence of multiple heterotrimeric complexes provides a molecular basis for the multiple roles of this highly conserved signaling system. The AMPKγ3 subunit is predominantly expressed in skeletal muscle, mostly in type II glycolytic fiber types. We determined whether the AMPKγ3 subunit has a role in signaling pathways that mediate mitochondrial biogenesis in skeletal muscle. We provide evidence that overexpression or ablation of the AMPKγ3 subunit does not appear to play a critical role in defining mitochondrial content in resting skeletal muscle. However, overexpression of a mutant form (R225Q) of the AMPKγ3 subunit (Tg-AMPKγ3225Q) increases mitochondrial biogenesis in glycolytic skeletal muscle. These adaptations are associated with an increase in expression of the co-activator [[PGC-1α]] and several transcription factors that regulate mitochondrial biogenesis, including NRF-1, NRF-2, and TFAM. Succinate dehydrogenase staining, a marker of the oxidative profile of individual fibers, was also increased in transversal skeletal muscle sections of white gastrocnemius muscle from Tg-AMPKγ3225Q mice, independent of changes in fiber type composition. In conclusion, a single nucleotide mutation (R225Q) in the AMPK gamma3 subunit is associated with mitochondrial biogenesis in glycolytic skeletal muscle, concomitant with increased expression of the co-activator [[PGC-1α]] and several transcription factors that regulate mitochondrial proteins, without altering fiber type composition. and several transcription factors that regulate mitochondrial proteins, without altering fiber type composition.)
Mungai 2011 Mol Cell Biol + (AMP-activated protein kinase (AMPK) is an … AMP-activated protein kinase (AMPK) is an energy sensor activated by increases in [AMP] or by oxidant stress (reactive oxygen species [ROS]). Hypoxia increases cellular ROS signaling, but the pathways underlying subsequent AMPK activation are not known. We tested the hypothesis that hypoxia activates AMPK by ROS-mediated opening of calcium release-activated calcium (CRAC) channels. Hypoxia (1.5% O2) augments cellular ROS as detected by the redox-sensitive green fluorescent protein (roGFP) but does not increase the [AMP]/[ATP] ratio. Increases in intracellular calcium during hypoxia were detected with Fura2 and the calcium-calmodulin fluorescence resonance energy transfer (FRET) sensor YC2.3. Antioxidant treatment or removal of extracellular calcium abrogates hypoxia-induced calcium signaling and subsequent AMPK phosphorylation during hypoxia. Oxidant stress triggers relocation of stromal interaction molecule 1 (STIM1), the endoplasmic reticulum (ER) Ca2+ sensor, to the plasma membrane. Knockdown of STIM1 by short interfering RNA (siRNA) attenuates the calcium responses to hypoxia and subsequent AMPK phosphorylation, while inhibition of L-type calcium channels has no effect. Knockdown of the AMPK upstream kinase LKB1 by siRNA does not prevent AMPK activation during hypoxia, but knockdown of CaMKKβ abolishes the AMPK response. These findings reveal that hypoxia can trigger AMPK activation in the apparent absence of increased [AMP] through ROS-dependent CRAC channel activation, leading to increases in cytosolic calcium that activate the AMPK upstream kinase CaMKKβ. activate the AMPK upstream kinase CaMKKβ.)
Zachariah 2014 Diabetes + (AMP-activated protein kinase (AMPK) is a h … AMP-activated protein kinase (AMPK) is a heterotrimeric complex, composed of a catalytic subunit (α) and two regulatory subunits (β and γ), which act as a metabolic sensor to regulate glucose and lipid metabolism. A mutation in the γ3 subunit (AMPKγ3(R225Q)) increases basal AMPK phosphorylation, while concomitantly reducing sensitivity to AMP. AMPKγ3(R225Q) (γ3(R225Q)) transgenic mice are protected against dietary-induced triglyceride accumulation and insulin resistance. We determined whether skeletal muscle-specific expression of AMPKγ3(R225Q) prevents metabolic abnormalities in leptin-deficient ob/ob (ob/ob-γ3(R225Q)) mice. Glycogen content was increased, triglyceride content was decreased, and diacylglycerol and ceramide content were unaltered in gastrocnemius muscle from ob/ob-γ3(R225Q) mice, whereas glucose tolerance was unaltered. Insulin-stimulated glucose uptake in extensor digitorum longus muscle during the euglycemic-hyperinsulinemic clamp was increased in lean γ3(R225Q) mice, but not in ob/ob-γ3(R225Q) mice. Acetyl-CoA carboxylase phosphorylation was increased in gastrocnemius muscle from γ3(R225Q) mutant mice independent of adiposity. Glycogen and triglyceride content were decreased after leptin treatment (5 days) in ob/ob mice, but not in ob/ob-γ3(R225Q) mice. In conclusion, metabolic improvements arising from muscle-specific expression of AMPKγ3(R225Q) are insufficient to ameliorate insulin resistance and obesity in leptin-deficient mice. Central defects due to leptin deficiency may override any metabolic benefit conferred by peripheral overexpression of the AMPKγ3(R225Q) mutation.rexpression of the AMPKγ3(R225Q) mutation.)
Dorigatti 2021 Geroscience + (AMP-activated protein kinase (AMPK) is a c … AMP-activated protein kinase (AMPK) is a central regulator of both lifespan and health across multiple model organisms. β-Guanidinopropionic acid (GPA) is an endogenous AMPK activator previously shown to improve metabolic function in young and obese mice. In this study, we tested whether age of administration significantly affects the physiological outcomes of GPA administration in mice. We report that intervention starting at 7-8 months (young) results in activation of AMPK signaling and a phenotype consisting of lower body mass, improved glucose control, enhanced exercise tolerance, and altered mitochondrial electron transport chain flux similar to previous reports. When GPA treatment is started at 18-19 months (old), the effect of GPA on AMPK signaling is blunted compared to younger mice despite similar accumulation of GPA in skeletal muscle. Even so, GPA administration in older animals delayed age-related declines in lean mass, improved measures of gait performance and circadian rhythm, and increased fat metabolism as measured by respiratory exchange ratio. These results are likely partially driven by the relative difference in basal function and metabolic plasticity between young and old mice. Our results suggest that age-related declines in AMPK sensitivity may limit potential strategies targeting AMPK signaling in older subjects and suggest that further research and development is required for AMPK activators to realize their full potential.ctivators to realize their full potential.)
Coelho 2015 Abstract Thyroid Cancer + (AMP-activated protein kinase (AMPK) is a s … AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that acts directly on cell proliferation and on transition from anaerobic to aerobic metabolic state. Our group showed that the activated form of AMPK (pAMPK) is overexpressed in papillary thyroid carcinoma (PTC) cases by immunohistochemistry. AMPK presents anti proliferative effects, so the biological meaning of AMPK activation in thyroid tumor cells and the consequences of its further activation on PTC metabolism is not known. We used the PTC-derived BCPAP cell line to analyze cellular responses to a further stimulation of AMPK with the pharmacological activator 5-aminoimidazole-4 carboxamide ribonucleoside (1 mM AICAR). Cell viability was measured by MTT, and apoptosis was analyzed by the expression of Annexin V by Muse cell analyser. ROS was measured by DCFHD probe by FACS. Oxygen consumption was measured using high-resolution respirometry (Oroboros). Hexokinase (HK) tertiary structure was evaluated on a spectrofluorometer (Jasco).BCPAP cells constitutively express high pAMPK levels, which correlates with the high glucose consumption rate (2 fold) and lactate production (2 fold), but lower oxygen consumption (30%) in these cells when compared to the nontumoral NTHYori cell line. AICAR exposure further stimulated these metabolic parameters, but decreased BCPAP cell viability (4 fold), with increased (1.5 fold) production of reactive oxygen species (ROS). HK is an enzyme of the glycolysis pathway that, upon binding to mitochondria, protects against ROS. We observed an increase in HK activity (1.4 fold) produced by AICAR, but not in its association with HK-mitochondrial activity. Purified HK experiments confirmed that ROS (100 μM Z2O2) alters the tertiary structure of HK decreasing its mitochondrial binding. The presence of NAC prevented cell death induced by AICAR treatment. Overall, these results suggest that, despite the upregulation of glucose metabolism by AMPK, chronic activation of the enzyme with AICAR increases ROS levels promoting a negative regulation of HK-mitochondrial binding. The further increase in ROS production induced by AICAR might play a role in the induction of tumor cell apoptosis. AICAR might play a role in the induction of tumor cell apoptosis.)
Canto 2009 Nature + (AMP-activated protein kinase (AMPK) is a m … AMP-activated protein kinase (AMPK) is a metabolic fuel gauge conserved along the evolutionary scale in eukaryotes that senses changes in the intracellular AMP/ATP ratio. Recent evidence indicated an important role for AMPK in the therapeutic benefits of metformin, thiazolidinediones and exercise, which form the cornerstones of the clinical management of type 2 diabetes and associated metabolic disorders. In general, activation of AMPK acts to maintain cellular energy stores, switching on catabolic pathways that produce ATP, mostly by enhancing oxidative metabolism and mitochondrial biogenesis, while switching off anabolic pathways that consume ATP. This regulation can take place acutely, through the regulation of fast post-translational events, but also by transcriptionally reprogramming the cell to meet energetic needs. Here we demonstrate that AMPK controls the expression of genes involved in energy metabolism in mouse skeletal muscle by acting in coordination with another metabolic sensor, the NAD+-dependent type III deacetylase SIRT1. AMPK enhances SIRT1 activity by increasing cellular NAD+ levels, resulting in the deacetylation and modulation of the activity of downstream SIRT1 targets that include the [[PGC-1alpha|peroxisome proliferator-activated receptor-gamma coactivator 1alpha]] and the forkhead box O1 (FOXO1) and O3 (FOXO3a) transcription factors. The AMPK-induced SIRT1-mediated deacetylation of these targets explains many of the convergent biological effects of AMPK and SIRT1 on energy metabolism.ts of AMPK and SIRT1 on energy metabolism.)
ASMRM 2021 Singapore SG + (ASMRM 2020, Singapore, SG, 2021)
Li 2014 Mol Cell Biol + (ATAD3 is a vital ATPase of the inner mitoc … ATAD3 is a vital ATPase of the inner mitochondrial membrane of pluri-cellular eucaryotes with largely unknown functions. Invalidation of ATAD3 blocks organism development at early stages requiring mitochondrial mass increase. Since ATAD3 knock-down (KD) in C. elegans inhibits first of all the development of adipocyte-like intestinal tissue, we used mouse adipocyte model 3T3-L1 cells to analyze ATAD3 functions during adipogenesis. By stable and transient modulation of ATAD3 expression in adipogenesis-induced 3T3-L1 cells, we show that (i) an increase in ATAD3 is preceding mitochondrial biogenesis and remodelling; (ii) down-regulation of ATAD3 inhibits adipogenesis, lipogenesis, and impedes overexpression of many mitochondrial proteins; (iii) ATAD3 re-expression rescues the phenotype of ATAD3 KD, and (iv) differentiation and lipogenesis are accelerated by ATAD3 overexpression, but inhibited by expression of a dominant-negative mutant. We further show that the ATAD3 KD phenotype is not due to altered insulin signal, but involves a limitation of mitochondrial biogenesis and remodelling linked to Drp1. These results demonstrate that ATAD3 is limiting for ''in vitro'' adipogenesis and lipogenesis.''in vitro'' adipogenesis and lipogenesis.)
Koopman 2015 Abstract MiP2015 + (ATP can be produced in the cytosol by glyc … ATP can be produced in the cytosol by glycolytic conversion of glucose (GLC) into pyruvate (PYR). The latter can be metabolized into lactate (LAC), which is released by the cell, or taken up by mitochondria to fuel ATP production by the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) system. Altering the balance between glycolytic and mitochondrial ATP generation is crucial for cell survival during mitoenergetic dysfunction, which is observed in a large variety of human disorders including cancer [1].To gain insight into the kinetic properties of this adaptive mechanism we here determined how acute (30 min) inhibition of OXPHOS affected cytosolic GLC homeostasis. GLC dynamics were analyzed in single living C2C12 myoblasts expressing the fluorescent biosensor FLII12Pglu-700µδ6 (FLII, [2]). Following ''in situ'' FLII calibration, the kinetic properties of GLC uptake (V1) and GLC consumption (V2) were determined independently and used to construct a minimal mathematical model of cytosolic GLC dynamics [3].After validating the model, it was applied to quantitatively predict V1 and V2 at steady-state (i.e. when V1=V2=Vsteady-state) in the absence and presence of OXPHOS inhibitors. Integrating model predictions with experimental data on LAC production, cell volume and oxygen consumption revealed that glycolysis and mitochondria equally contribute to cellular ATP production in control myoblasts. Inhibition of OXPHOS induced a 2-fold increase in Vsteady-state and glycolytic ATP production flux. Both in the absence and presence of OXPHOS inhibitors, GLC was consumed at near maximal rates, meaning that GLC consumption is rate-limiting under steady-state conditions.Taken together, we here demonstrate that OXPHOS inhibition increases steady-state GLC uptake and consumption in C2C12 myoblasts [3]. The latter activation fully compensates for the reduction in mitochondrial ATP production, thereby maintaining the balance between cellular ATP supply and demand. The underlying mechanistic aspects and further consequences of this phenomenon [e.g. 4,5] are currently investigated.non [e.g. 4,5] are currently investigated.)
Liemburg-Apers 2015 Biophys J + (ATP can be produced in the cytosol by glyc … ATP can be produced in the cytosol by glycolytic conversion of glucose (GLC) into pyruvate. The latter can be metabolized into lactate, which is released by the cell, or taken up by mitochondria to fuel ATP production by the tricarboxylic acid cycle and oxidative phosphorylation (OXPHOS) system. Altering the balance between glycolytic and mitochondrial ATP generation is crucial for cell survival during mitoenergetic dysfunction, which is observed in a large variety of human disorders including cancer. To gain insight into the kinetic properties of this adaptive mechanism we determined here how acute (30 min) inhibition of OXPHOS affected cytosolic GLC homeostasis. GLC dynamics were analyzed in single living C2C12 myoblasts expressing the fluorescent biosensor FLII(12)Pglu-700μδ6 (FLII). Following ''in situ'' FLII calibration, the kinetic properties of GLC uptake (V1) and GLC consumption (V2) were determined independently and used to construct a minimal mathematical model of cytosolic GLC dynamics. After validating the model, it was applied to quantitatively predict V1 and V2 at steady-state (i.e., when V1 = V2 = Vsteady-state) in the absence and presence of OXPHOS inhibitors. Integrating model predictions with experimental data on lactate production, cell volume, and O2 consumption revealed that glycolysis and mitochondria equally contribute to cellular ATP production in control myoblasts. Inhibition of OXPHOS induced a twofold increase in Vsteady-state and glycolytic ATP production flux. Both in the absence and presence of OXPHOS inhibitors, GLC was consumed at near maximal rates, meaning that GLC consumption is rate-limiting under steady-state conditions. Taken together, we demonstrate here that OXPHOS inhibition increases steady-state GLC uptake and consumption in C2C12 myoblasts. This activation fully compensates for the reduction in mitochondrial ATP production, thereby maintaining the balance between cellular ATP supply and demand.Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.shed by Elsevier Inc. All rights reserved.)
Pesout MiP2010 + (ATP decreases rapidly during ischemia. It … ATP decreases rapidly during ischemia. It is then degraded to adenosine, which moves to the extracellular space and activates adenosine receptors (ADOR). ADOR play a unique role in cardioprotection against ischemia reperfusion injury, because their activation is responsible for cardioprotection by ischemic preconditioning and ischemic postconditioning.onditioning and ischemic postconditioning.)
Bundgaard 2019 Sci Rep + (ATP depletion and succinate accumulation d … ATP depletion and succinate accumulation during ischemia lead to oxidative damage to mammalian organs upon reperfusion. In contrast, freshwater turtles survive weeks of anoxia at low temperatures without suffering from oxidative damage upon reoxygenation, but the mechanisms are unclear. To determine how turtles survive prolonged anoxia, we measured ~80 metabolites in hearts from cold-acclimated (5 °C) turtles exposed to 9 days anoxia and compared the results with those for normoxic turtles (25 °C) and mouse hearts exposed to 30 min of ischemia. In turtles, ATP and ADP decreased to new steady-state levels during fasting and cold-acclimation and further with anoxia, but disappeared within 30 min of ischemia in mouse hearts. High NADH/NAD+ ratios were associated with succinate accumulation in both anoxic turtles and ischemic mouse hearts. However, succinate concentrations and succinate/fumarate ratios were lower in turtle than in mouse heart, limiting the driving force for production of reactive oxygen species (ROS) upon reoxygenation in turtles. Furthermore, we show production of ROS from succinate is prevented by re-synthesis of ATP from ADP. Thus, maintenance of an ATP/ADP pool and low succinate accumulation likely protects turtle hearts from anoxia/reoxygenation injury and suggests metabolic interventions as a therapeutic approach to limit ischemia/reperfusion injury in mammals.roach to limit ischemia/reperfusion injury in mammals.)
Ley-Ngardigal 2022 FEBS J + (ATP is the most universal and essential en … ATP is the most universal and essential energy molecule in cells. This is due to its ability to store cellular energy in form of high-energy phosphate bonds, which are extremely stable and readily usable by the cell. This energy is key for a variety of biological functions such as cell growth and division, metabolism, and signaling, and for the turnover of biomolecules. Understanding how ATP is produced and hydrolyzed with a spatiotemporal resolution is necessary to understand its functions both in physiological and in pathological contexts. In this review, first we will describe the organization of the electron transport chain and ATP synthase, the main molecular motor for ATP production in mitochondria. Second, we will review the biochemical assays currently available to estimate ATP quantities in cells, and we will compare their readouts, strengths, and weaknesses. Finally, we will explore the palette of genetically encoded biosensors designed for microscopy-based approaches, and show how their spatiotemporal resolution opened up the possibility to follow ATP levels in living cells.lity to follow ATP levels in living cells.)
Nuskova 2015 Abstract MiPschool London 2015 + (ATP produced by the mitochondrial FoF1-ATP … ATP produced by the mitochondrial FoF1-ATP synthase represents a major source of energy for aerobic organisms. Unsurprisingly, ATP synthase deficiencies are associated with severe pathologic phenotypes. To shed light on the functional consequences of ATP synthase deficiencies, we utilised a model of HEK293 cell line and explored the effect of RNAi mediated knockdown of the three subunits (γ, δ and ε) forming the central stalk of the enzyme connecting Fo and F1 domains.For functional evaluations of ATP synthase deficiencies, 10 stable knockdown clones with down-regulated subunits γ (ATP5C1 gene), δ (ATP5D gene), or ε (ATP5E gene) have been selected. The protein content of ATP synthase subunit α among the knockdown clones covers the range of 40–100 % as compared to controls. Further characterization of these clones revealed 2–78 % oligomycin-sensitive ATPase hydrolytic activity that parallels a decrease in the content of fully assembled ATP synthase complex.Two aspects of cellular energetics have been examined in detail, specifically respiration and glycolysis, using the Seahorse XFe24 analyser. Our results indicate that the clones with less than 30 % of residual ATPase activity switched their metabolism to enhanced glycolysis. There is a decrease in their basal respiration rate relatively to their respiratory capacity (47 vs 61 % in controls) and in parallel, their basal glycolytic rates utilise by up to 20 % more of their glycolytic capacity. These findings clearly demonstrate metabolic adaptations of these cells. On the other hand, the clones with more than 30 % residual ATPase activity displayed a change neither in the respiration nor in their basal glycolytic rate. In the case of ATP synthase deficiency, the mitochondrial membrane potential is expected to rise, which would then stimulate the production of reactive oxygen species (ROS). Indeed, the γ knockdown clones with a very low residual ATPase activity exhibit elevated ROS production. With respect to the role of the oxidative stress in ATP synthase deficiencies, we aim to examine oxidative damage of cell structures and the content of antioxidant enzymes.In conclusion, using these model clones, we are planning on investigating the effect of ATP synthase deficiency on the mitochondrial energetics, oxidative stress, energy state, and cell viability and define the threshold residual activity of ATP synthase for the presentation of pathological phenotype. At this moment, our data suggest that the threshold for metabolic remodelling equals to approximately 30 % of ATPase activity. to approximately 30 % of ATPase activity.)
Cortassa 2022 J Mol Cell Cardiol + (ATP synthase (F1Fo) is a rotary molecular … ATP synthase (F1Fo) is a rotary molecular engine that harnesses energy from electrochemical-gradients across the inner mitochondrial membrane for ATP synthesis. Despite the accepted tenet that F1Fo transports exclusively H+, our laboratory has demonstrated that, in addition to H+, F1Fo ATP synthase transports a significant fraction of ΔΨm-driven charge as K+ to synthesize ATP. Herein, we utilize a computational modeling approach as a proof of principle of the feasibility of the core mechanism underlying the enhanced ATP synthesis, and to explore its bioenergetic consequences. A minimal model comprising the 'core' mechanism constituted by ATP synthase, driven by both proton (PMF) and potassium motive force (KMF), respiratory chain, adenine nucleotide translocator, Pi carrier, and K+/H+ exchanger (KHEmito) was able to simulate enhanced ATP synthesis and respiratory fluxes determined experimentally with isolated heart mitochondria. This capacity of F1Fo ATP synthase confers mitochondria with a significant energetic advantage compared to K+ transport through a channel not linked to oxidative phosphorylation (OxPhos). The K+-cycling mechanism requires a KHEmito that exchanges matrix K+ for intermembrane space H+, leaving PMF as the overall driving energy of OxPhos, in full agreement with the standard chemiosmotic mechanism. Experimental data of state 4➔3 energetic transitions, mimicking low to high energy demand, could be reproduced by an integrated computational model of mitochondrial function that incorporates the 'core' mechanism. Model simulations display similar behavior compared to the experimentally observed changes in ΔΨm, mitochondrial K+ uptake, matrix volume, respiration, and ATP synthesis during the energetic transitions at physiological pH and K+ concentration. The model also explores the role played by KHEmito in modulating the energetic performance of mitochondria. The results obtained support the available experimental evidence on ATP synthesis driven by K+ and H+ transport through the F1Fo ATP synthase.+ transport through the F1Fo ATP synthase.)
Juhaszova 2021 Function (Oxf) + (ATP synthase (F1F&l … ATP synthase (F1Fo) synthesizes daily our body's weight in ATP, whose production-rate can be transiently increased several-fold to meet changes in energy utilization. Using purified mammalian F1Fo-reconstituted proteoliposomes and isolated mitochondria, we show F1Fo can utilize both Δ''Ψ''mt-driven H+- and K+-transport to synthesize ATP under physiological pH = 7.2 and K+ = 140 mEq/L conditions. Purely K+-driven ATP synthesis from single F1Fo molecules measured by bioluminescence photon detection could be directly demonstrated along with simultaneous measurements of unitary K+ currents by voltage clamp, both blocked by specific Fo inhibitors. In the presence of K+, compared to osmotically-matched conditions in which this cation is absent, isolated mitochondria display 3.5-fold higher rates of ATP synthesis, at the expense of 2.6-fold higher rates of oxygen consumption, these fluxes being driven by a 2.7:1 K+: H+ stoichiometry. The excellent agreement between the functional data obtained from purified F1Fo single molecule experiments and ATP synthase studied in the intact mitochondrion under unaltered OxPhos coupling by K+ presence, is entirely consistent with K+ transport through the ATP synthase driving the observed increase in ATP synthesis. Thus, both K+ (harnessing Δ''Ψ''mt) and H+ (harnessing its chemical potential energy, Δ''μ''H) drive ATP generation during normal physiology.istent with K+ transport through the ATP synthase driving the observed increase in ATP synthesis. Thus, both K+ (harnessing Δ''Ψ''mt) and H+ (harnessing its chemical potential energy, Δ''μ''H) drive ATP generation during normal physiology.)
Juhaszova 2019 bioRxiv + (ATP synthase (F1F&l … ATP synthase (F1Fo) synthesizes daily our body’s weight in ATP, whose production-rate can be transiently increased several-fold. Using purified mammalian F1Fo-reconstituted proteoliposomes and isolated mitochondria, we show that F1Fo utilizes both H+- and K+-transport (because of >106-fold K+ excess vs H+) to drive ATP synthesis with the H+:K+ permeability of ~106:1. F1Fo can be upregulated by endogenous survival-related proteins (Bcl-xL, Mcl-1) and synthetic molecules (diazoxide, pinacidil) to increase its chemo-mechanical efficiency via IF1. Increasing K+- and H+-driven ATP synthesis enables F1Fo to operate as a primary mitochondrial K+-uniporter regulating energy supply-demand matching, and as the recruitable mitochondrial KATP-channel that can limit ischemia-reperfusion injury. Isolated mitochondria in the presence of K+ can sustain ~3.5-fold higher ATP-synthesis-flux (vs K+ absence) driven by a 2.7:1 K+:H+ stoichiometry with unaltered OxPhos coupling. Excellent agreement between F1Fo single-molecule and intact-mitochondria experiments is consistent with K+-transport through ATP synthase driving a major fraction of ATP synthesis. (vs K+ absence) driven by a 2.7:1 K+:H+ stoichiometry with unaltered OxPhos coupling. Excellent agreement between F1Fo single-molecule and intact-mitochondria experiments is consistent with K+-transport through ATP synthase driving a major fraction of ATP synthesis.)
Walker 1994 Curr Opin Struct Biol + (ATP synthase is regulated so as to prevent … ATP synthase is regulated so as to prevent futile hydrolysis of ATP when the transmembrane proton electrochemical gradient, delta mu H+, falls. Mitochondria and chloroplasts have different mechanisms for inhibition of ATP synthase: by binding an inhibitor protein, and by stabilization of the ADP-inhibited state by making an intramolecular disulphide bond, respectively. The recently determined structure of bovine F1-ATPase is locked in a conformation that probably represents the ADP-inhibited state of the enzyme.nts the ADP-inhibited state of the enzyme.)
Klusch 2017 Elife + (ATP synthases produce ATP by rotary cataly … ATP synthases produce ATP by rotary catalysis, powered by the electrochemical proton gradient across the membrane. Understanding this fundamental process requires an atomic model of the proton pathway. We determined the structure of an intact mitochondrial ATP synthase dimer by electron cryo-microscopy at near-atomic resolution. Charged and polar residues of the a-subunit stator define two aqueous channels, each spanning one half of the membrane. Passing through a conserved membrane-intrinsic helix hairpin, the lumenal channel protonates an acidic glutamate in the c-ring rotor. Upon ring rotation, the protonated glutamate encounters the matrix channel and deprotonates. An arginine between the two channels prevents proton leakage. The steep potential gradient over the sub-nm inter-channel distance exerts a force on the deprotonated glutamate, resulting in net directional rotation.te, resulting in net directional rotation.)
Morciano 2017 Nat Protoc + (ATP, the energy exchange factor that conne … ATP, the energy exchange factor that connects anabolism and catabolism, is required for major reactions and processes that occur in living cells, such as muscle contraction, phosphorylation and active transport. ATP is also the key molecule in extracellular purinergic signaling mechanisms, with an established crucial role in inflammation and several additional disease conditions. Here, we describe detailed protocols to measure the ATP concentration in isolated living cells and animals using luminescence techniques based on targeted luciferase probes. In the presence of magnesium, oxygen and ATP, the protein luciferase catalyzes oxidation of the substrate luciferin, which is associated with light emission. Recombinantly expressed wild-type luciferase is exclusively cytosolic; however, adding specific targeting sequences can modify its cellular localization. Using this strategy, we have constructed luciferase chimeras targeted to the mitochondrial matrix and the outer surface of the plasma membrane. Here, we describe optimized protocols for monitoring ATP concentrations in the cytosol, mitochondrial matrix and pericellular space in living cells via an overall procedure that requires an average of 3 d. In addition, we present a detailed protocol for the in vivo detection of extracellular ATP in mice using luciferase-transfected reporter cells. This latter procedure may require up to 25 d to complete.cedure may require up to 25 d to complete.)
Bayot 2014 Biochimie + (ATP-dependent proteases are currently emer … ATP-dependent proteases are currently emerging as key regulators of mitochondrial functions. Among these proteolytic systems, Lon protease is involved in the control of selective protein turnover in the mitochondrial matrix. In the absence of Lon, yeast cells have been shown to accumulate electron-dense inclusion bodies in the matrix space, to loose integrity of mitochondrial genome and to be respiratory deficient. In order to address the role of Lon in mitochondrial functionality in human cells, we have set up a HeLa cell line stably transfected with a vector expressing a shRNA under the control of a promoter which is inducible with doxycycline. We have demonstrated that reduction of Lon protease results in a mild phenotype in this cell line in contrast with what have been observed in other cell types such as WI-38 fibroblasts. Nevertheless, deficiency in Lon protease led to an increase in ROS production and to an accumulation of carbonylated protein in the mitochondria. Our study suggests that Lon protease has a wide variety of targets and is likely to play different roles depending of the cell type.ifferent roles depending of the cell type.)
Kahancova 2018 FEBS Lett + (ATPase Inhibitory factor 1 (IF1) is an end … ATPase Inhibitory factor 1 (IF1) is an endogenous regulator of mitochondrial ATP synthase, which is involved in cellular metabolism. Although great progress has been made, biological roles of IF1 and molecular mechanisms of its action are still to be elucidated. Here, we show that IF1 is present in pancreatic β-cells, bound to the ATP synthase also under normal physiological conditions. IF1 silencing in model pancreatic β-cells (INS-1E) increases insulin secretion over a range of glucose concentrations. The left-shifted dose-response curve reveals excessive insulin secretion even under low glucose, corresponding to fasting conditions. A parallel increase in cellular respiration and ATP levels is observed. To conclude, our results indicate that IF1 is a negative regulator of insulin secretion involved in pancreatic β-cell glucose sensing.lved in pancreatic β-cell glucose sensing.)
ATSPB 2023 Hall AT + (ATSPB 2023, Hall in Tirol, Austria, 2023)
Gnaiger 2000 Transplant Proc + (AUTOOXIDATION reactions of highly reduced … AUTOOXIDATION reactions of highly reduced organic compounds are a source of reactive oxygen species that contribute to ischemia/reperfusion injury. Antioxidants such as reduced glutathione (GSH; g-glutamylcysteinylglycine) are added to organ preservation solutions to reduce oxidative stress.1,2 GSH is unstable, however, in University of Wisconsin (UW) solution in the presence of oxygen.3 To our knowledge, no reports are available on the stability of GSH in other organ preservation solutions, such as histidine-tryptophan-ketoglutarate (HTK) or Celsior solution. The present study reports for the first time a quantitative comparison of autooxidation of GSH in a variety of established preservation solutions, demonstrating in particular the high stability of GSH in HTK solution.nstrating in particular the high stability of GSH in HTK solution.)
ARVO 2018 Honolulu HI US + (AVRO - Association for Research in Vision and Ophthalmology, Honolulu, Hawaii, USA, 2018)
Abcam Mitochondria Meeting 2014 + (Abcam Mitochondria Meeting 2014, London, UK; [http://www.abcam.com/index.html?pageconfig=resource&rid=16185&viapagetrap=mitochondriafeb Abcam Mitochondria Meeting 2014])
Bricambert 2018 Nat Commun + (Aberrant histone methylation profile is re … Aberrant histone methylation profile is reported to correlate with the development and progression of NAFLD during obesity. However, the identification of specific epigenetic modifiers involved in this process remains poorly understood. Here, we identify the histone demethylase Plant Homeodomain Finger 2 (Phf2) as a new transcriptional co-activator of the transcription factor Carbohydrate Responsive Element Binding Protein (ChREBP). By specifically erasing H3K9me2 methyl-marks on the promoter of ChREBP-regulated genes, Phf2 facilitates incorporation of metabolic precursors into mono-unsaturated fatty acids, leading to hepatosteatosis development in the absence of inflammation and insulin resistance. Moreover, the Phf2-mediated activation of the transcription factor NF-E2-related factor 2 (Nrf2) further reroutes glucose fluxes toward the pentose phosphate pathway and glutathione biosynthesis, protecting the liver from oxidative stress and fibrogenesis in response to diet-induced obesity. Overall, our findings establish a downstream epigenetic checkpoint, whereby Phf2, through facilitating H3K9me2 demethylation at specific gene promoters, protects liver from the pathogenesis progression of NAFLD.rom the pathogenesis progression of NAFLD.)
Wu 2018 Adv Sci + (Aberrant mitochondrial energy transfer und … Aberrant mitochondrial energy transfer underlies prevalent chronic health conditions, including cancer, cardiovascular, and neurodegenerative diseases. Mitochondrial transplantation represents an innovative strategy aimed at restoring favorable metabolic phenotypes in cells with dysfunctional energy metabolism. While promising, significant barriers to ''in vivo'' translation of this approach abound, including limited cellular uptake and recognition of mitochondria as foreign. The objective is to functionalize isolated mitochondria with a biocompatible polymer to enhance cellular transplantation and eventual ''in vivo'' applications. Herein, it is demonstrated that grafting of a polymer conjugate composed of dextran with triphenylphosphonium onto isolated mitochondria protects the organelles and facilitates cellular internalization compared with uncoated mitochondria. Importantly, mitochondrial transplantation into cancer and cardiovascular cells has profound effects on respiration, mediating a shift toward improved oxidative phosphorylation, and reduced glycolysis. These findings represent the first demonstration of polymer functionalization of isolated mitochondria, highlighting a viable strategy for enabling clinical applications of mitochondrial transplantation.ications of mitochondrial transplantation.)
Scrima 2020 bioRxiv + (Abnormal hemoglobins can have major conseq … Abnormal hemoglobins can have major consequences for tissue delivery of oxygen. Correct diagnosis of hemoglobinopathies with altered oxygen affinity requires a determination of hemoglobin oxygen dissociation curve (ODC), which relates the hemoglobin oxygen saturation to the partial pressure of oxygen in the blood. Determination of the ODC of human hemoglobin is typically carried out under conditions in which hemoglobin is in equilibrium with O2 at each partial pressure. However, in the human body due to the fast transit of RBCs through tissues hemoglobin oxygen exchanges occur under non-equilibrium conditions. We describe the determination of non-equilibrium ODC, and show that under these conditions Hb cooperativity has two apparent components in the Adair, Perutz, and MWC models of Hb. The first component, which we call sequential cooperativity, accounts for ∼70% of Hb cooperativity, and emerges from the constraint of sequential binding that is shared by the three models. The second component, which we call conformational cooperativity, accounts for ∼30% of Hb cooperativity, and is due either to a conformational equilibrium between low affinity and high affinity tetramers (as in the MWC model), or to a conformational change from low to high affinity once two of the tetramer sites are occupied (Perutz model).two of the tetramer sites are occupied (Perutz model).)
Szabo 2020 Int J Mol Sci + (Abnormal tau protein aggregation in the br … Abnormal tau protein aggregation in the brain is a hallmark of tauopathies, such as frontotemporal lobar degeneration and Alzheimer's disease. Substantial evidence has been linking tau to neurodegeneration, but the underlying mechanisms have yet to be clearly identified. Mitochondria are paramount organelles in neurons, as they provide the main source of energy (adenosine triphosphate) to these highly energetic cells. Mitochondrial dysfunction was identified as an early event of neurodegenerative diseases occurring even before the cognitive deficits. Tau protein was shown to interact with mitochondrial proteins and to impair mitochondrial bioenergetics and dynamics, leading to neurotoxicity. In this review, we discuss in detail the different impacts of disease-associated tau protein on mitochondrial functions, including mitochondrial transport, network dynamics, mitophagy and bioenergetics. We also give new insights about the effects of abnormal tau protein on mitochondrial neurosteroidogenesis, as well as on the endoplasmic reticulum-mitochondria coupling. A better understanding of the pathomechanisms of abnormal tau-induced mitochondrial failure may help to identify new targets for therapeutic interventions.new targets for therapeutic interventions.)
Valis 2017 Oncotarget + (Abnormalities in cancer metabolism represe … Abnormalities in cancer metabolism represent potential targets for cancer therapy. We have recently identified a natural compound Quambalarine B (QB), which inhibits proliferation of several leukemic cell lines followed by cell death. We have predicted ubiquinone binding sites of mitochondrial respiratory complexes as potential molecular targets of QB in leukemia cells. Hence, we tracked the effect of QB on leukemia metabolism by applying several omics and biochemical techniques. We have confirmed the inhibition of respiratory complexes by QB and found an increase in the intracellular AMP levels together with respiratory substrates. Inhibition of mitochondrial respiration by QB triggered reprogramming of leukemic cell metabolism involving disproportions in glycolytic flux, inhibition of proteins O-glycosylation, stimulation of glycine synthesis pathway, and pyruvate kinase activity, followed by an increase in pyruvate and a decrease in lactate levels. Inhibition of mitochondrial complex I by QB suppressed folate metabolism as determined by a decrease in formate production. We have also observed an increase in cellular levels of several amino acids except for aspartate, indicating the dependence of Jurkat (T-ALL) cells on aspartate synthesis. These results indicate blockade of mitochondrial complex I and II activity by QB and reduction in aspartate and folate metabolism as therapeutic targets in T-ALL cells. Anti-cancer activity of QB was also confirmed during ''in vivo'' studies, suggesting the therapeutic potential of this natural compound.peutic potential of this natural compound.)
Roy Chowdhury 2018 Mol Cell Neurosci + (Abnormalities in mitochondrial function un … Abnormalities in mitochondrial function under diabetic conditions can lead to deficits in function of cortical neurons and their support cells exhibiting a pivotal role in the pathogenesis of several neurodegenerative disorders, including Alzheimer's disease. We aimed to assess mitochondrial respiration rates and membrane potential or H2O2 generation simultaneously and expression of proteins involved in mitochondrial dynamics, ROS scavenging and AMPK/SIRT/PGC-1α pathway activity in cortex under diabetic conditions.Cortical mitochondria from streptozotocin (STZ)-induced type 1 diabetic rats or mice, and aged-matched controls were used for simultaneous measurements of mitochondrial respiration rates and mitochondrial membrane potential (mtMP) or H2O2 using Oroboros oxygraph. Measurements of enzymatic activities of respiratory complexes were performed using spectophotometry. Protein levels in cortical mitochondria and homogenates were determined by Western blotting.Mitochondrial coupled respiration rates and FCCP-induced uncoupled respiration rates were significantly decreased in mitochondria of cortex of STZ-diabetic rats compared to controls. The mtMP in the presence of ADP was significantly depolarized and succinate-dependent respiration rates and H2O2 were significantly diminished in cortical mitochondria of diabetic animals compared to controls, accompanied with reduced expression of CuZn- and Mn-superoxide dismutase. The enzymatic activities of Complex I, II, and IV and protein levels of certain components of Complex I and II, mitofusin 2 (Mfn2), dynamin-related protein 1 (DRP1), P-AMPK, SIRT2 and PGC-1α were significantly diminished in diabetic cortex.Deficits in mitochondrial function, dynamics, and antioxidant capabilities putatively mediated through sub-optimal AMPK/SIRT/PGC-1α signaling, are involved in the development of early sub-clinical neurodegeneration in the cortex under diabetic conditions.Copyright © 2018. Published by Elsevier Inc.degeneration in the cortex under diabetic conditions. Copyright © 2018. Published by Elsevier Inc.)
Jaramillo-Jimenez 2023 Mitochondrion + (Abnormalities in the Tri-Carboxylic-Acid ( … Abnormalities in the Tri-Carboxylic-Acid (TCA) cycle have been documented in dementia. Through network analysis, TCA cycle metabolites could indirectly reflect known dementia-related abnormalities in biochemical pathways, and key metabolites might be associated with prognosis. This study analyzed TCA cycle metabolites as predictors of cognitive decline in a mild dementia cohort and explored potential interactions with the diagnosis of Lewy Body Dementia (LBD) or Alzheimer's Disease (AD) and APOE-ε4 genotype. We included 145 mild dementia patients (LBD = 59; AD = 86). Serum TCA cycle metabolites were analyzed at baseline, and partial correlation networks were conducted. Cognitive performance was measured annually over 5-years with the Mini-mental State Examination. Longitudinal mixed-effects Tobit models evaluated each baseline metabolite as a predictor of 5-years cognitive decline. APOE-ε4 and diagnosis interactions were explored. Results showed comparable metabolite concentrations in LBD and AD. Multiple testing corrected networks showed larger coefficients for a negative correlation between pyruvate - succinate and positive correlations between fumarate - malate and citrate - Isocitrate in both LBD and AD. In the total sample, adjusted mixed models showed significant associations between baseline citrate concentration and longitudinal MMSE scores. In APOE-ε4 carriers, baseline isocitrate predicted MMSE scores. We conclude that, in mild dementia, serum citrate concentrations could be associated with subsequent cognitive decline, as well as isocitrate concentrations in APOE-ε4 carriers. Downregulation of enzymatic activity in the first half of the TCA cycle (decarboxylating dehydrogenases), with upregulation in the latter half (dehydrogenases only), might be indirectly reflected in serum TCA cycle metabolites' networks. in serum TCA cycle metabolites' networks.)
Ahluwalia 2017 Sci Rep + (About two decades ago, West and coworkers … About two decades ago, West and coworkers established a model which predicts that metabolic rate follows a three quarter power relationship with the mass of an organism, based on the premise that tissues are supplied nutrients through a fractal distribution network. Quarter power scaling is widely considered a universal law of biology and it is generally accepted that were in-vitro cultures to obey allometric metabolic scaling, they would have more predictive potential and could, for instance, provide a viable substitute for animals in research. This paper outlines a theoretical and computational framework for establishing quarter power scaling in three-dimensional spherical constructs in-vitro, starting where fractal distribution ends. Allometric scaling in non-vascular spherical tissue constructs was assessed using models of Michaelis Menten oxygen consumption and diffusion. The models demonstrate that physiological scaling is maintained when about 5 to 60% of the construct is exposed to oxygen concentrations less than the Michaelis Menten constant, with a significant concentration gradient in the sphere. The results have important implications for the design of downscaled in-vitro systems with physiological relevance.itro systems with physiological relevance.)
Skalska 2009 Int J Mol Sci + (Abstract: The mitochondrial response to ch … Abstract: The mitochondrial response to changes of cytosolic calcium concentration has a strong impact on neuronal cell metabolism and viability. We observed that Ca2+ additions to isolated rat brain mitochondria induced in potassium ion containing media a mitochondrial membrane potential depolarization and an accompanying increase of mitochondrial respiration. These Ca2+ effects can be blocked by iberiotoxin and charybdotoxin, well known inhibitors of large conductance potassium channel (BKCa channel). Furthermore, NS1619 – a BKCa channel opener – induced potassium ion–specific effects on brain mitochondria similar to those induced by Ca2+. These findings suggest the presence of a calcium-activated, large conductance potassium channel (sensitive to charybdotoxin and NS1619), which was confirmed by reconstitution of the mitochondrial inner membrane into planar lipid bilayers. The conductance of the reconstituted channel was 265 pS under gradient (50/450 mM KCl) conditions. Its reversal potential was equal to 50 mV, which proved that the examined channel was cation-selective. We also observed immunoreactivity of anti-β4 subunit (of the BKCa channel) antibodies with ~26 kDa proteins of rat brain mitochondria. Immunohistochemical analysis confirmed the predominant occurrence of anti-β4 subunit in neuronal mitochondria. We hypothesize that the mitochondrial BKCa channel represents a calcium sensor, which can contribute to neuronal signal transduction and survival.hannel represents a calcium sensor, which can contribute to neuronal signal transduction and survival.)
Klein 2018 Int J Digit Libr + (Academic publishers claim that they add va … Academic publishers claim that they add value to scholarly communications by coordinating reviews and contributing and enhancing text during publication. These contributions come at a considerable cost: US academic libraries paid $1.7 billion for serial subscriptions in 2008 alone. Library budgets, in contrast, are flat and not able to keep pace with serial price inflation. We have investigated the publishers’ value proposition by conducting a comparative study of pre-print papers from two distinct science, technology, and medicine corpora and their final published counterparts. This comparison had two working assumptions: (1) If the publishers’ argument is valid, the text of a pre-print paper should vary measurably from its corresponding final published version, and (2) by applying standard similarity measures, we should be able to detect and quantify such differences. Our analysis revealed that the text contents of the scientific papers generally changed very little from their pre-print to final published versions. These findings contribute empirical indicators to discussions of the added value of commercial publishers and therefore should influence libraries’ economic decisions regarding access to scholarly publications.egarding access to scholarly publications.)
Teixeira 2022 J Gen Philos Sci + (Academic publishing is undergoing a highly … Academic publishing is undergoing a highly transformative process, and many established rules and value systems that are in place, such as traditional peer review (TPR) and preprints, are facing unprecedented challenges, including as a result of post-publication peer review. The integrity and validity of the academic literature continue to rely naively on blind trust, while TPR and preprints continue to fail to effectively screen out errors, fraud, and misconduct. Imperfect TPR invariably results in imperfect papers that have passed through varying levels of rigor of screening and validation. If errors or misconduct were not detected during TPR's editorial screening, but are detected at the post-publication stage, an opportunity is created to correct the academic record. Currently, the most common forms of correcting the academic literature are errata, corrigenda, expressions of concern, and retractions or withdrawals. Some additional measures to correct the literature have emerged, including manuscript versioning, amendments, partial retractions and retract and replace. Preprints can also be corrected if their version is updated. This paper discusses the risks, benefits and limitations of these forms of correcting the academic literature.rms of correcting the academic literature.)
Coelho 2016 Oncol Rep + (Acceleration of glycolysis is a characteri … Acceleration of glycolysis is a characteristic of neoplasia. Previous studies have shown that a metabolic shift occurs in many tumors and correlates with a negative prognosis. The present study aimed to investigate the glycolytic profile of thyroid carcinoma cell lines. We investigated glycolytic and oxidative parameters of two thyroid carcinoma papillary cell lines (BCPAP and TPC1) and the non-tumor cell line NTHY-ori. All carcinoma cell lines showed higher rates of glycolysis efficiency, when compared to NTHY-ori, as assessed by a higher rate of glucose consumption and lactate production. The BCPAP cell line presented higher rates of growth, as well as elevated intracellular ATP levels, compared to the TPC1 and NTHY-ori cells. We found that glycolysis and activities of pentose phosphate pathway (PPP) regulatory enzymes were significantly different among the carcinoma cell lines, particularly in the mitochondrial hexokinase (HK) activity which was higher in the BCPAP cells than that in the TPC1 cell line which showed a balanced distribution of HK activity between cytoplasmic and mitochondrial subcellular localizations. However, TPC1 had higher levels of glucose‑6-phosphate dehydrogenase activity, suggesting that the PPP is elevated in this cell type. Using high resolution respirometry, we observed that the Warburg effect was present in the BCPAP and TPC1 cells, characterized by low oxygen consumption and high reactive oxygen species production. Overall, these results indicate that both thyroid papillary carcinoma cell lines showed a glycolytic profile. Of note, BCPAP cells presented some relevant differences in cell metabolism compared to TPC1 cells, mainly related to higher mitochondrial-associated HK activity.gher mitochondrial-associated HK activity.)
Acclimatization and High Altitude Illness - Facts and Myths 2017 Brixen Dolomites IT + (Acclimatization and High Altitude Illness - Facts and Myths, Brixen Dolomites, IT)
Arias-Reyes 2023 MitoFit + (Acclimatization to high altitude relies on … Acclimatization to high altitude relies on adjustments of cellular metabolism that optimize oxygen use and energy production. In tissues with high energy demand and almost exclusive reliance on aerobic metabolism such as the brain, hypoxia is a particularly strong stressor, however, strategies to adjust metabolic pathways for successful high-altitude acclimatization remain poorly understood. Compared to SD rats, FVB mice show successful acclimatization to high altitude, we, therefore, used this model to investigate metabolic adjustments in the retrosplenial cortex (a key area of the brain involved in spatial learning and navigation) in normoxia and during acclimatization to hypoxia (12 % O2 – 1, 7, and 21 days). We measured in simultaneous the rates of ATP synthesis and O2 consumption in fresh permeabilized brain samples by coupled high-resolution respirometry and fluorometry. We quantified the citrate synthase (CS) activity as an index of mitochondrial content, the transcriptional regulation of genes involved in mitochondrial dynamics; and the activity of enzymes representative of the glycolytic, aerobic, and anaerobic metabolism. Our findings show that acclimatization to hypoxia significantly increases ATP synthesis in mice and to a lower extent in rats. In mice, this occurs in parallel with a reduction of O2 consumption, and a three-fold increase in the P»/O ratio. In rats, a six-fold increase in CS activity and altered mitochondrial dynamics gene expression are evident. Finally, activities of glycolytic, aerobic, or anaerobic enzymes remain overall unchanged in both species except for a transient glycolytic and anaerobic peak at day 7 in mice. Altogether, our results show that chronic hypoxia optimizes the efficiency of mitochondrial ATP synthesis in the retrosplenial cortex of mice. Contrastingly, rats sustain the production of ATP only by increasing mitochondrial content and altering mitochondrial dynamics, suggesting drastic mitochondrial malfunctions. ing mitochondrial dynamics, suggesting drastic mitochondrial malfunctions. )
Schoenfeld 2016 J Cereb Blood Flow Metab + (According to recent reports, systemic trea … According to recent reports, systemic treatment of rats with methylpalmoxirate (carnitine palmitoyltransferase-1 inhibitor) decreased peroxidation of polyunsaturated fatty acids in brain tissue. This was taken as evidence of mitochondrial β-oxidation in brain, thereby contradicting long-standing paradigms of cerebral metabolism, which claim that β-oxidation of activated fatty acids has minor importance for brain energy homeostasis. We addressed this controversy. Our experiments are the first direct experimental analysis of this question. We fueled isolated brain mitochondria or rat brain astrocytes with octanoic acid, but octanoic acid does not enhance formation of reactive oxygen species, neither in isolated brain mitochondria nor in astrocytes, even at limited hydrogen delivery to mitochondria. Thus, octanoic acid or l-octanoylcarnitine does not stimulate H2O2 release from brain mitochondria fueled with malate, in contrast to liver mitochondria (2.25-fold rise). This does obviously not support the possible occurrence of β-oxidation of the fatty acid octanoate in the brain. We conclude that a proposed inhibition of β-oxidation does not seem to be a helpful strategy for therapies aiming at lowering oxidative stress in cerebral tissue. This question is important, since oxidative stress is the cause of neurodegeneration in numerous neurodegenerative or inflammatory disease situations.© The Author(s) 2016.erative or inflammatory disease situations. © The Author(s) 2016.)
Roskams T Falk Workshop Inflammation & Cancer + (According to the cancer stem cell concept, … According to the cancer stem cell concept, hepatocellular carcinoma (HCC) consists of a hierarchy of cell populations, of which the very small cancer stem cell population is the one that has the growth and metastatic potential of the tumour. The other neoplastic cells are offspring of the cancer stem cells and each can differentiate a little differently, according to the local microenvironment in each part of the tumor, hence explaining the enormous phenotypic heterogeneity of a neoplasm. Current therapeutic strategies mostly target rapidly growing differentiated tumour cells. However the results are often unsatisfactory because of the chemoresistance of HCC. New therapies targeting cancer stem cells should therefore be developed. A prerequisite is a good understanding of the mechanisms of activation and differentiation of normal stem/progenitor cells in normal and diseased liver. Hepatocytes and cholangiocytes have stem cell features, but also progenitor cells, located in the smallest branches of the biliary tree. These cells are especially activated in the cirrhotic stage of chronic liver diseases, the stage in which HCC develops. HCC with progenitor cell features, possibly reflecting a progenitor cell origin, have a very bad prognosis and therefore should be recognized and treated accordingly.uld be recognized and treated accordingly.)
Huetter 2007 Aging Cell + (According to the free radical theory of ag … According to the free radical theory of aging, reactive oxygen species (ROS) act as a driving force of the aging process, and it is generally believed that mitochondrial dysfunction is a major source of increased oxidative stress in tissues with high content of mitochondria, such as muscle or brain. However, recent experiments in mouse models of premature aging have questioned the role of mitochondrial ROS production in premature aging. To address the role of mitochondrial impairment and ROS production for aging in human muscles, we have analyzed mitochondrial properties in muscle fibres isolated from the vastus lateralis of young and elderly donors. Mitochondrial respiratory functions were addressed by high-resolution respirometry, and ROS production was analyzed by in situ staining with the redox-sensitive dye dihydroethidium. We found that aged human skeletal muscles contain fully functional mitochondria and that the level of ROS production is higher in young compared to aged muscle. Accordingly, we could not find any increase in oxidative modification of proteins in muscle from elderly donors. However, the accumulation of lipofuscin was identified as a robust marker of human muscle aging. The data support a model, where ROS-induced molecular damage is continuously removed, preventing the accumulation of dysfunctional mitochondria despite ongoing ROS production.tochondria despite ongoing ROS production.)
Huisamen 2015 Abstract MiPschool Cape Town 2015 + (According to the latest statistics, variou … According to the latest statistics, various cardiovascular diseasesaccounted for 8.3% of natural deaths in South Africa during 2013,ranking the 6th place as cause of mortality. With the efficiencyof therapies aimed at decreasing mortality from heart disease, lifeexpectancy increased. As result of this, the focus of recent researchchanged towards understanding the energy demands of the heart inorder to optimize function. Because of its high energetic needs, thehuman heart utilizes between 3.5 and 6 kg of ATP per day to function.This is produced by its mitochondrial populations which occupy up to50% of the volume of a cardiomyocyte. A close link therefore existsbetween mitochondrial dysfunction and heart disease. In addition, thereis growing recognition that inborn errors of metabolism can influencecardiomyocyte dysfunction [1] and that primary inherited mitochondrialdiseases display a full spectrum of cardiac disorders [2].ATM is a 350kDa serine/threonine protein kinase displaying homologiesto the large protein family of PI3-Kinases, although it lacks the ability tophosphorylate lipids [3]. It came under scrutiny because of the disease,Ataxia-telangiectasie (A-T), which is an autosomal, recessive disorderthat progressively affects multiple organs. This disease is caused bymutations in the Atm gene, resulting in lack or inactivation of the ATMprotein [4]. ATM in the cell can be localized to the nucleus, cytoplasm ofmitochondria.We became interested in myocardial ATM because it was found thatskeletal muscle of insulin resistant, obese rats had dramatically reducedlevels of the so-called ATM protein, in association with the well-knownreduced activation of the insulin/ phosphatidylinositol 3 kinases (PI3-kinase)/PKB/Akt pathway, which is the main mechanism of relaying themetabolic effects of insulin [5]. Foster et al [6] found structural and functional changes in the hearts of ATM KO mice, using echocardiography andDoppler echocardiography.The mitochondrial association of ATM protein kinase plays an importantrole in its integrity and functioning such that ATM deficiency results indefects in mitochondrial respiration [7]. ATM also regulates mitochondrialbiogenesis and DNA content [8]. In addition, it was demonstrated that amitochondria-targeted antioxidant MitoQ, could decrease the features ofthe metabolic syndrome in ATM+/-ApoE-/- mice [9]. This may be becauseone of the mechanisms known to activate the ATM protein is increasedoxidative stress. Activated ATM initiates an anti-oxidant response basedon a metabolic shift while, in fibroblast cell lines, inactivation of ATMis associated with increased ROS levels followed by expression andactivation of the transcription factor HIF-1alpha [10]. the transcription factor HIF-1alpha [10].)
Kozieł 2011 J Invest Dermatol + (According to the mitochondrial theory of a … According to the mitochondrial theory of aging, reactive oxygen species (ROS) derived primarily from mitochondria cause cumulative oxidative damage to various cellular molecules and thereby contribute to the aging process. On the other hand, a pivotal role of the proteasome, as a main proteolytic system implicated in the degradation of oxidized proteins during aging, is suggested. In this study, we analyzed mitochondrial function in dermal fibroblasts derived from biopsies obtained from healthy young, middle-aged, and old donors. We also determined proteasome activity in these cells, using a degron-destabilized green fluorescent protein (GFP)-based reporter protein. We found a significant decrease in mitochondrial membrane potential in samples from aged donors, accompanied by a significant increase in ROS levels. Respiratory activity was not significantly altered with donor age, probably reflecting genetic variation. Proteasome activity was significantly decreased in fibroblasts from middle-aged donors compared with young donors; fibroblasts derived from the oldest donors displayed a high heterogeneity in this assay. We also found intraindividual coregulation of mitochondrial and proteasomal activities in all human fibroblast strains tested, suggesting that both systems are interdependent. Accordingly, pharmacological inhibition of the proteasome led to decreased mitochondrial function, whereas inhibition of mitochondrial function in turn reduced proteasome activity.ction in turn reduced proteasome activity.)
Schiffer 2013 Abstract MiP2013 + (According to the rate-of-living and oxidat … According to the rate-of-living and oxidative damage theory of aging, extended lifespan is predicted by low energy metabolism and low reactive oxygen species production rates. Recently, several studies show that dietary inorganic nitrate mainly present in vegetables can reduce oxygen consumption during physical exercise in humans [1] and contribute to attenuated oxidative stress in animal models of disease [2]. Nitrate accumulates in saliva and is bioactivated through reduction to nitrite by oral bacteria. We examined the effects of dietary nitrate on basal metabolic rate (BMR) and markers of oxidative stress in man using a double-blind, randomized cross over design. 15 young healthy males volunteered and indirect calorimetry was used to determine basal metabolic rate after three days of dietary intervention with sodium nitrate (NaNO3, 0.1 mmol∙kg-1∙day-1) or placebo (NaCl). The administered amount of nitrate resembles what is found in 100-300 g of nitrate rich vegetables such as beetroot or spinach. The intervention reduced BMR by 4.3% after nitrate administration compared with placebo (p<0.02). A strong negative correlation was found between the change in salivary nitrate and the change in BMR (r2=0.72; p<0.002). In addition, nitrate supplementation reduced plasma levels of malondialdehyde, indicating lower oxidative stress as a result of the intervention. Thyroid hormone status was unaffected.The cuisines of cultures known for their longevity are usually rich in vegetables and future studies will reveal whether this life span extension is linked to the high nitrate content in this food group. to the high nitrate content in this food group.)
Nelson 2016 J Fish Biol + (Accounting for energy use by fishes has be … Accounting for energy use by fishes has been taking place for over 200 years. The original, and continuing gold standard for measuring energy use in terrestrial animals, is to account for the waste heat produced by all reactions of metabolism, a process referred to as direct calorimetry. Direct calorimetry is not easy or convenient in terrestrial animals and is extremely difficult in aquatic animals. Thus, the original and most subsequent measurements of metabolic activity in fishes have been measured via indirect calorimetry. Indirect calorimetry takes advantage of the fact that oxygen is consumed and carbon dioxide is produced during the catabolic conversion of foodstuffs or energy reserves to useful ATP energy. As measuring [CO2] in water is more challenging than measuring [O2], most indirect calorimetric studies on fishes have used the rate of O2 consumption. To relate measurements of O2 consumption back to actual energy usage requires knowledge of the substrate being oxidized. Many contemporary studies of O2 consumption by fishes do not attempt to relate this measurement back to actual energy usage. Thus, the rate of oxygen consumption has become a measurement in its own right that is not necessarily synonymous with metabolic rate. Because all extant fishes are obligate aerobes (many fishes engage in substantial net anaerobiosis, but all require oxygen to complete their life cycle), this discrepancy does not appear to be of great concern to the fish biology community, and reports of fish oxygen consumption, without being related to energy, have proliferated. Unfortunately, under some circumstances, these measures can be quite different from one another. A review of the methodological history of the two measurements and a look towards the future are included.view of the methodological history of the two measurements and a look towards the future are included.)
Fitzgerald 2024 J Cachexia Sarcopenia Muscle + (Accumulating evidence has demonstrated tha … Accumulating evidence has demonstrated that chronic tobacco smoking directly contributes to skeletal muscle dysfunction independent of its pathological impact to the cardiorespiratory systems. The mechanisms underlying tobacco smoke toxicity in skeletal muscle are not fully resolved. In this study, the role of the aryl hydrocarbon receptor (AHR), a transcription factor known to be activated with tobacco smoke, was investigated.AHR related gene (mRNA) expression was quantified in skeletal muscle from adult controls and patients with chronic obstructive pulmonary disease (COPD), as well as mice with and without cigarette smoke exposure. Utilizing both skeletal muscle-specific AHR knockout mice exposed to chronic repeated (5 days per week for 16 weeks) cigarette smoke and skeletal muscle-specific expression of a constitutively active mutant AHR in healthy mice, a battery of assessments interrogating muscle size, contractile function, mitochondrial energetics, and RNA sequencing were employed.Skeletal muscle from COPD patients (N = 79, age = 67.0 ± 8.4 years) had higher levels of AHR (P = 0.0451) and CYP1B1 (P < 0.0001) compared to healthy adult controls (N = 16, age = 66.5 ± 6.5 years). Mice exposed to cigarette smoke displayed higher expression of Ahr (P = 0.008), Cyp1b1 (P < 0.0001), and Cyp1a1 (P < 0.0001) in skeletal muscle compared to air controls. Cigarette smoke exposure was found to impair skeletal muscle mitochondrial oxidative phosphorylation by ~50% in littermate controls (Treatment effect, P < 0.001), which was attenuated by deletion of the AHR in muscle in male (P = 0.001), but not female, mice (P = 0.37), indicating there are sex-dependent pathological effects of smoking-induced AHR activation in skeletal muscle. Viral mediated expression of a constitutively active mutant AHR in the muscle of healthy mice recapitulated the effects of cigarette smoking by decreasing muscle mitochondrial oxidative phosphorylation by ~40% (P = 0.003).These findings provide evidence linking chronic AHR activation secondary to cigarette smoke exposure to skeletal muscle bioenergetic deficits in male, but not female, mice. AHR activation is a likely contributor to the decline in muscle oxidative capacity observed in smokers and AHR antagonism may provide a therapeutic avenue aimed to improve muscle function in COPD.eutic avenue aimed to improve muscle function in COPD.)
Ying 2008 Antioxid Redox Signal + (Accumulating evidence has suggested that N … Accumulating evidence has suggested that NAD (including NAD+ and NADH) and NADP (including NADP+ and NADPH) could belong to the fundamental common mediators of various biological processes, including energy metabolism, mitochondrial functions, calcium homeostasis, antioxidation/generation of oxidative stress, gene expression, immunological functions, aging, and cell death: First, it is established that NAD mediates energy metabolism and mitochondrial functions; second, NADPH is a key component in cellular antioxidation systems; and NADH-dependent reactive oxygen species (ROS) generation from mitochondria and NADPH oxidase-dependent ROS generation are two critical mechanisms of ROS generation; third, cyclic ADP-ribose and several other molecules that are generated from NAD and NADP could mediate calcium homeostasis; fourth, NAD and NADP modulate multiple key factors in cell death, such as mitochondrial permeability transition, energy state, poly(ADP-ribose) polymerase-1, and apoptosis-inducing factor; and fifth, NAD and NADP profoundly affect aging-influencing factors such as oxidative stress and mitochondrial activities, and NAD-dependent sirtuins also mediate the aging process. Moreover, many recent studies have suggested novel paradigms of NAD and NADP metabolism. Future investigation into the metabolism and biological functions of NAD and NADP may expose fundamental properties of life, and suggest new strategies for treating diseases and slowing the aging process.ew strategies for treating diseases and slowing the aging process.)
Abu Bakar 2020 Eur J Pharmacol + (Accumulating evidence indicates that adipo … Accumulating evidence indicates that adipose tissue inflammation and mitochondrial dysfunction in skeletal muscle are inextricably linked to obesity and insulin resistance. Celastrol, a bioactive compound derived from the root of Tripterygium wilfordii exhibits a number of attributive properties to attenuate metabolic dysfunction in various cellular and animal disease models. However, the underlying therapeutic mechanisms of celastrol in the obesogenic environment "in vivo" remain elusive. Therefore, the current study investigated the metabolic effects of celastrol on insulin sensitivity, inflammatory response in adipose tissue and mitochondrial functions in skeletal muscle of the high fat diet (HFD)-induced obese rats. Our study revealed that celastrol supplementation at 3 mg/kg/day for 8 weeks significantly reduced the final body weight and enhanced insulin sensitivity of the HFD-fed rats. Celastrol noticeably improved insulin-stimulated glucose uptake activity and increased expression of plasma membrane GLUT4 protein in skeletal muscle. Moreover, celastrol-treated HFD-fed rats showed attenuated inflammatory responses via decreased NF-κB activity and diminished mRNA expression responsible for classically activated macrophage (M1) polarization in adipose tissues. Significant improvement of muscle mitochondrial functions and enhanced antioxidant defense machinery via restoration of mitochondrial complexes I + III linked activity were effectively exhibited by celastrol treatment. Mechanistically, celastrol stimulated mitochondrial biogenesis attributed by upregulation of the adenosine monophosphate-activated protein kinase (AMPK) and sirtuin 1 (SIRT1) signaling pathways. Together, these results further demonstrate heretofore the conceivable therapeutic mechanisms of celastrol "in vivo" against HFD-induced obesity mediated through attenuation of inflammatory response in adipose tissue and enhanced mitochondrial functions in skeletal muscle.itochondrial functions in skeletal muscle.)
Arena 2018 Mol Cell + (Accumulating evidence indicates that the M … Accumulating evidence indicates that the MDM2 oncoprotein promotes tumorigenesis beyond its canonical negative effects on the p53 tumor suppressor, but these p53-independent functions remain poorly understood. Here, we show that a fraction of endogenous MDM2 is actively imported in mitochondria to control respiration and mitochondrial dynamics independently of p53. Mitochondrial MDM2 represses the transcription of NADH-dehydrogenase 6 (MT-ND6) ''in vitro'' and ''in vivo'', impinging on respiratory complex I activity and enhancing mitochondrial ROS production. Recruitment of MDM2 to mitochondria increases during oxidative stress and hypoxia. Accordingly, mice lacking MDM2 in skeletal muscles exhibit higher MT-ND6 levels, enhanced complex I activity, and increased muscular endurance in mild hypoxic conditions. Furthermore, increased mitochondrial MDM2 levels enhance the migratory and invasive properties of cancer cells. Collectively, these data uncover a previously unsuspected function of the MDM2 oncoprotein in mitochondria that play critical roles in skeletal muscle physiology and may contribute to tumor progression.y and may contribute to tumor progression.)
Yang 2018 Cell Death Dis + (Accumulating evidence revealed that mesenc … Accumulating evidence revealed that mesenchymal stem cells (MSCs) confer cardioprotection against myocardial infarction (MI). However, the poor survival and engraftment rate of the transplanted cells limited their therapeutic efficacy in the heart. The enhanced leptin production associated with hypoxia preconditioning contributed to the improved MSCs survival. Mitochondrial integrity determines the cellular fate. Thus, we aimed to investigate whether leptin can enhance mitochondrial integrity of human MSCs (hMSCs) to protect against various stress. ''In vivo'', transplantation of leptin-overexpressing hMSCs into the infarcted heart resulted in improved cell viability, leading to enhanced angiogenesis and cardiac function. ''In vitro'', pretreatment of hMSCs with recombinant leptin (hMSCs-Leppre) displayed improved cell survival against severe ischemic condition (glucose and serum deprivation under hypoxia), which was associated with increased mitochondrial fusion. Subsequently, Optic atrophy 1 (OPA1), a mitochondrial inner membrane protein that regulates fusion and cristae structure, was significantly elevated in the hMSCs-Leppre group, and the protection of leptin was abrogated by targeting OPA1 with a selective siRNA. Furthermore, OMA1, a mitochondrial protease that cleaves OPA1, decreased in a leptin-dependent manner. Pretreatment of cells with an inhibitor of the proteasome (MG132), prevented leptin-induced OMA1 degradation, implicating the ubiquitination/proteasome system as a part of the protective leptin pathway. In addition, GSK3 inhibitor (SB216763) was also involved in the degradation of OMA1. In conclusion, in the hostile microenvironment caused by MI, (a) leptin can maintain the mitochondrial integrity and prolong the survival of hMSCs; (b) leptin-mediated mitochondrial integrity requires phosphorylation of GSK3 as a prerequisite for ubiquitination-depended degradation of OMA1 and attenuation of long-OPA1 cleavage. Thus, leptin targeting the GSK3/OMA1/OPA1 signaling pathway can optimize hMSCs therapy for cardiovascular diseases such as MI.can optimize hMSCs therapy for cardiovascular diseases such as MI.)
Yan 2015 BMC Cancer + (Accumulating evidence suggests that breast … Accumulating evidence suggests that breast cancer involves tumour-initiating cells (TICs), which play a role in initiation, metastasis, therapeutic resistance and relapse of the disease. Emerging drugs that target TICs are becoming a focus of contemporary research. Mitocans, a group of compounds that induce apoptosis of cancer cells by destabilising their mitochondria, are showing their potential in killing TICs. In this project, we investigated mitochondrially targeted vitamin E succinate (MitoVES), a recently developed mitocan, for its ''in vitro'' and ''in vivo'' efficacy against TICs.The mammosphere model of breast TICs was established by culturing murine NeuTL and human MCF7 cells as spheres. This model was verified by stem cell marker expression, tumour initiation capacity and chemotherapeutic resistance. Cell susceptibility to MitoVES was assessed and the cell death pathway investigated. ''In vivo'' efficacy was studied by grafting NeuTL TICs to form syngeneic tumours.Mammospheres derived from NeuTL and MCF7 breast cancer cells were enriched in the level of stemness, and the sphere cells featured altered mitochondrial function. Sphere cultures were resistant to several established anti-cancer agents while they were susceptible to MitoVES. Killing of mammospheres was suppressed when the mitochondrial complex II, the molecular target of MitoVES, was knocked down. Importantly, MitoVES inhibited progression of syngeneic HER2(high) tumours derived from breast TICs by inducing apoptosis in tumour cells.These results demonstrate that using mammospheres, a plausible model for studying TICs, drugs that target mitochondria efficiently kill breast tumour-initiating cells.ently kill breast tumour-initiating cells.)
Braganza 2019 Mol Aspects Med + (Accumulating studies demonstrate that mito … Accumulating studies demonstrate that mitochondrial genetics and function are central to determining the susceptibility to, and prognosis of numerous diseases across all organ systems. Despite this recognition, mitochondrial function remains poorly characterized in humans primarily due to the invasiveness of obtaining viable tissue for mitochondrial studies. Recent studies have begun to test the hypothesis that circulating blood cells, which can be obtained by minimally invasive methodology, can be utilized as a biomarker of systemic bioenergetic function in human populations. Here we present the available methodologies for assessing blood cell bioenergetics and review studies that have applied these techniques to healthy and disease populations. We focus on the validation of this methodology in healthy subjects, as well as studies testing whether blood cell bioenergetics are altered in disease, correlate with clinical parameters, and compare with other methodology for assessing human mitochondrial function. Finally, we present the challenges and goals for the development of this emerging approach into a tool for translational research and personalized medicine.Copyright © 2019 Elsevier Ltd. All rights reserved. 2019 Elsevier Ltd. All rights reserved.)
Amaral 2016 J Neurochem + (Accumulation of 2-methylcitric acid (2MCA) … Accumulation of 2-methylcitric acid (2MCA) is observed in methylmalonic and propionic acidemias, which are clinically characterized by severe neurological symptoms. The exact pathogenetic mechanisms of brain abnormalities in these diseases are poorly established and very little has been reported on the role of 2MCA. In the present work we found that 2MCA markedly inhibited ADP-stimulated and uncoupled respiration in mitochondria supported by glutamate, with a less significant inhibition in pyruvate plus malate-respiring mitochondria. However, no alterations occurred when α-ketoglutarate or succinate was used as respiratory substrates, suggesting a defect on glutamate oxidative metabolism. It was also observed that 2MCA decreased ATP formation in glutamate plus malate or pyruvate plus malate-supported mitochondria. Furthermore, 2MCA inhibited glutamate dehydrogenase (GDH) activity at concentrations as low as 0.5 mM. Kinetic studies revealed that this inhibitory effect was competitive in relation to glutamate. In contrast, assays of osmotic swelling in non-respiring mitochondria suggested that 2MCA did not significantly impair mitochondrial glutamate transport. Finally, 2MCA provoked a significant decrease of mitochondrial membrane potential and induced swelling in Ca2+ -loaded mitochondria supported by different substrates. These effects were totally prevented by cyclosporine A plus ADP or ruthenium red, indicating induction of mitochondrial permeability transition (PT). Taken together, our data strongly indicate that 2MCA behaves as a potent inhibitor of glutamate oxidation by inhibiting GDH activity and as a PT inducer, disturbing mitochondrial energy homeostasis. We presume that 2MCA-induced mitochondrial deleterious effects may contribute to the pathogenesis of brain damage in patients affected by methylmalonic and propionic acidemias. This article is protected by copyright. All rights reserved.rticle is protected by copyright. All rights reserved.)
Liu 2002 Proc Natl Acad Sci U S A + (Accumulation of oxidative damage to mitoch … Accumulation of oxidative damage to mitochondria, protein, and nucleic acid in the brain may lead to neuronal and cognitive dysfunction. The effects on cognitive function, brain mitochondrial structure, and biomarkers of oxidative damage were studied after feeding old rats two mitochondrial metabolites, acetyl-l-carnitine (ALCAR) [0.5% or 0.2% (wt/vol) in drinking water], and/or R-alpha-lipoic acid (LA) [0.2% or 0.1% (wt/wt) in diet]. Spatial memory was assessed by using the Morris water maze; temporal memory was tested by using the peak procedure (a time-discrimination procedure). Dietary supplementation with ALCAR and/or LA improved memory, the combination being the most effective for two different tests of spatial memory (''P'' < 0.05; ''P'' < 0.01) and for temporal memory (P < 0.05). Immunohistochemical analysis showed that oxidative damage to nucleic acids (8-hydroxyguanosine and 8-hydroxy-2'-deoxyguanosine) increased with age in the hippocampus, a region important for memory. Oxidative damage to nucleic acids occurred predominantly in RNA. Dietary administration of ALCAR and/or LA significantly reduced the extent of oxidized RNA, the combination being the most effective. Electron microscopic studies in the hippocampus showed that ALCAR and/or LA reversed age-associated mitochondrial structural decay. These results suggest that feeding ALCAR and LA to old rats improves performance on memory tasks by lowering oxidative damage and improving mitochondrial function.dative damage and improving mitochondrial function.)
Schoettl 2015 Endocrinology + (Accumulation of visceral fat is associated … Accumulation of visceral fat is associated with metabolic risk whereas excessive amounts of peripheral fat are considered less problematic. At the same time, altered white adipocyte mitochondrial bioenergetics has been implicated in the pathogenesis of insulin resistance and type 2 diabetes.We therefore investigated whether the metabolic risk of visceral versus peripheral fat coincides with a difference in mitochondrial capacity of white adipocytes. We assessed bioenergetic parameters of subcutaneous inguinal and visceral epididymal white adipocytes from male C57BL/6N mice employing a comprehensive respirometry setup of intact and permeabilized adipocytes as well as isolated mitochondria. Inguinal adipocytes clearly featured a higher respiratory capacity attributable to increased mitochondrial respiratory chain content as compared to epididymal adipocytes. The lower capacity of mitochondria from epididymal adipocytes was accompanied by an increased generation of reactive oxygen species per oxygen consumed. Feeding a high-fat diet for one week reduced white adipocyte mitochondrial capacity, with stronger effects in epididymal when compared to inguinal adipocytes. This was accompanied by impaired body glucose homeostasis. Therefore, the limited bioenergetic performance combined with the proportionally higher generation of reactive oxygen species of visceral adipocytes could be seen as a candidate mechanism mediating the elevated metabolic risk associated with this fat depot.bolic risk associated with this fat depot.)
Gnaiger 1990 Thermochim Acta + (Accurate definitions of efficiency are req … Accurate definitions of efficiency are required to resolve controversies on the significance and comparability of measures of efficiency in biological energetics. This review on concepts of efficiency is arranged into 4 parts. First, some fundamental energy relations of equilibrium and nonequilibrium thermodynamics are defined and placed into a coherent context as relevant for efficiency in biology. The classical expression of the Carnot efficiency of a heat engine obtains a new meaning in terms of flux-force relations of nonequilibrium thermodynamics. Second, within this general thermodynamic frame, the specific treatment of energy transformations of chemical reactions is introduced, with particular emphasis on open systems with internal transformation and external transfer of matter. Third, the chemical transformations in ATP turnover and internal efficiencies of coupled reactions are analyzed in two parts. On the one hand, the enthalpy efficiency is relevant in the context of biological calorimetry in relation to uncoupling and the integration of aerobic and anaerobic metabolism. On the other hand, the molar Gibbs energy efficiency relates to the driving force of coupled reactions and to the control of flux. High metabolic power and maximum efficiency are mutually exclusive. Finally, the discussion of various expressions of efficiency in biological growth requires a careful distinction between energy conservation in transformations (chemical reactions) and energy acquisition in coupled transformation and transfer of energy in the form of externally supplied matter. Better understanding and management of biological resource utilization requires this combined analysis of efficiency in biological energetics.is of efficiency in biological energetics.)
Lotkova 2009 Acta Vet Brno + (Acetaminophen (AAP) overdose causes severe … Acetaminophen (AAP) overdose causes severe liver injury and is the leading cause of acute liver injury in humans. The mechanisms participating in its toxic effect are glutathione depletion, oxidative stress and mitochondrial dysfunction. S-adenosylmethionine (SAMe) is the principal biological methyl donor and is also a precursor of glutathione. In our previous studies we have documented a protective action of SAMe against various toxic injuries of rat hepatocytes in primary cultures. The aim of this study was to evaluate a possible protective effect of SAMe against AAP-induced toxic injury of primary rat hepatocytes. Hepatocytes were exposed to AAP (2.5 mM) or AAP together with SAMe at the final concentrations of 5, 25 or 50 mg/l for 24 h. Incubation of hepatocytes with AAP caused a significant increase of the leakage of lactate dehydrogenase (LDH) (p < 0.001) and decline of the activity of cellular dehydrogenases (WST- 1) (p < 0.001). Co-incubation of hepatocytes with SAMe at any dose did not improve these markers of cellular integrity. The functional indicators improved in hepatocytes co-cultured with SAMe - urea production was significantly increased when using the highest dose of SAMe (p < 0.05); albumin synthesis was higher in all cultured hepatocytes exposed to SAMe (p < 0.05). SAMe did not influence AAP-induced decrease of cellular content of glutathione. Mitochondrial respiration of harvested digitonin-permeabilized hepatocytes was measured; Complex II was more sensitive to toxic action of AAP, respiration was decreased by 20%. This decrease was completely abolished by SAMe.y 20%. This decrease was completely abolished by SAMe.)
Vrbova 2015 Abstract MiPschool London 2015 + (Acetaminophen (APAP) belongs to the most u … Acetaminophen (APAP) belongs to the most used analgetic and antipyretic drugs. APAP overdose causes liver injury and that is why it is the most frequent cause of acute liver injuries in the Western countries. In some cases, it is also associated with renal impairment occurring with frequency 1-2% of patients with acetaminophen overdose [1,2]. Acetaminophen is detoxified by three major pathways, glucuronidation, sulfation and oxidation by cytochrome P450. At therapeutic doses, a small portion of APAP dose is oxidized by cytochrome P450 to a reactive electrophilic molecule (NAPQI). After overdose, APAP is metabolized predominantly through the oxidation pathway and production of the oxidation product is enhanced. NAPQI is considered to be the toxic metabolite causing cell impairment [3]. However, based on our preliminary results, we postulated, that another metabolite could also cause toxicity.Our study's aim was to characterize the toxicity of APAP metabolite in the human HK-2 cell line. We used a range of concentrations (10-5 mM) to examine the toxicity in cells. We evaluated the toxicity using the detection of mitochondrial dehydrogenase activity (WST-1 test), lactate dehydrogenase activity assay and detection of intracellular ROS production. We observed moderate impairment of cells already after 3 h of treatment based on the finding of decreased mitochondrial dehydrogenase activity in all tested concentrations. After 24 hours, the results showed significant cellular impairment and increased ROS production at all tested concentrations. In conclusion, we have proven our hypothesis that APAP metabolites ought to be also concerned in APAP toxicity. The toxic effect is presumably apparent as a decrease in mitochondrial dehydrogenase activity and induction of ROS production. activity and induction of ROS production.)
Kucera 2016 Drug Chem Toxicol + (Acetaminophen (APAP) hepatotoxicity is oft … Acetaminophen (APAP) hepatotoxicity is often studied in primary cultures of hepatocytes of various species, but there are only few works comparing interspecies differences in susceptibility of hepatocytes to APAP ''in vitro''.The aim of our work was to compare hepatotoxicity of APAP in rat and mouse hepatocytes in primary cultures.Hepatocytes isolated from male Wistar rats and C57Bl/6J mice were exposed to APAP for up to 24 h. We determined lactate dehydrogenase (LDH) activity in culture medium, activity of cellular dehydrogenases (WST-1) and activity of caspases 3 in cell lysate as markers of cell damage/death. We assessed content of intracellular reduced glutathione, production of reactive oxygen species (ROS) and malondialdehyde (MDA). Respiration of digitonin-permeabilized hepatocytes was measured by high resolution respirometry and mitochondrial membrane potential (MMP) was visualized (JC-1).APAP from concentrations of 2.5 and 0.75 mmol/L induced a decrease in viability of rat (p < 0.001) and mouse (p < 0.001) hepatocytes (WST-1), respectively. In contrast to rat hepatocytes, there was no activation of caspase-3 in mouse hepatocytes after APAP treatment. Earlier damage to plasma membrane and faster depletion of reduced glutathione were detected in mouse hepatocytes. Mouse hepatocytes showed increased glutamate + malate-driven respiration in state 4 and higher susceptibility of the outer mitochondrial membrane (OMM) to APAP-induced injury.APAP displayed dose-dependent toxicity in hepatocytes of both species. Mouse hepatocytes in primary culture however had approximately three-fold higher susceptibility to the toxic effect of APAP when compared to rat hepatocytes.effect of APAP when compared to rat hepatocytes.)
Rousarova 2015 Abstract MiPschool London 2015 + (Acetaminophen (APAP) is a frequently used … Acetaminophen (APAP) is a frequently used analgetic and antipyretic drug. After overdose, it may cause a number of pathophysiological processes that can even lead to acute liver and/or kidney failure. The cause of toxicity can be recognized in its metabolic activation but the entire mechanism of acetaminophen toxicity is still unknown. APAP is metabolized in hepatocytes through various pathways. The most important pathway acting in overdose is oxidation of APAP by cytochrome P450 to a substance, which is detoxified by reaction with glutathione [1,2]. We suppose that the metabolite of acetaminophen can also cause toxicity. Thus the main goal of our study was to assess a possible toxic effect of this metabolite in isolated mitochondria using detection of ROS production. We used CM-H2DCFDA molecular probe that is nonfluorescent until oxidized by ROS [3]. We used isolated mitochondria from rat liver and from kidney cells treated with mitochondrial substrates and inhibitors to localize the site of ROS production. We proved that kidney mitochondria and mitochondria from rat liver treated with the acetaminophen metabolite produced ROS in significantly higher extent in comparison with controls. In 5 mM solution, ROS production in mitochondria isolated from rat liver was enhanced 9-fold and 3-fold in presence of glutamate and malate (i.e. complex I-related) and succinate and rotenone (i.e. complex II-related), respectively. Similar results were found in mitochondria isolated from kidney cells. The results support our hypothesis about the possible toxic effect of acetaminophen metabolite likely contributing to the overall toxicity.kely contributing to the overall toxicity.)
Chroeis 2019 Basic Clin Pharmacol Toxicol + (Acetaminophen (APAP) is used worldwide and … Acetaminophen (APAP) is used worldwide and is regarded as safe in therapeutic concentrations but can cause acute liver failure in higher doses. High doses of APAP have been shown to inhibit complex I and II mitochondrial respiratory capacity in mouse hepatocytes, but human studies are lacking. Here, we studied mitochondrial respiratory capacity in human hepatic tissue ''ex vivo'' with increasing doses of APAP. Hepatic biopsies were obtained from 12 obese patients who underwent a Roux-en-Y gastric bypass (RYGB) or a sleeve gastrectomy surgery. Mitochondrial respiration was measured by high-resolution respirometry. Therapeutic concentrations (≤0.13 mmol/L) of APAP did not inhibit state 3 complex I-linked respiration. APAP concentrations of ≥2.0 mmol/L in the medium significantly reduced hepatic mitochondrial respiration in a dose-dependent manner. Complex II-linked mitochondrial respiration was not inhibited by APAP. We conclude that the mitochondrial respiratory capacity is affected by a hepato-toxic effect of APAP, which involved complex I, but not complex II.© 2019 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).(former Nordic Pharmacological Society).)
Piel 2020 PLoS One + (Acetaminophen is one of the most common ov … Acetaminophen is one of the most common over-the-counter pain medications used worldwide and is considered safe at therapeutic dose. However, intentional and unintentional overdose accounts for up to 70 % of acute liver failure cases in the western world. Extensive research has demonstrated that the induction of oxidative stress and mitochondrial dysfunction are central to the development of acetaminophen-induced liver injury. Despite the insight gained on the mechanism of acetaminophen toxicity, there still is only one clinically approved pharmacological treatment option, N-acetylcysteine. N-acetylcysteine increases the cell's antioxidant defense and protects liver cells from further acetaminophen-induced oxidative damage. Because it primarily protects healthy liver cells rather than rescuing the already injured cells alternative treatment strategies that target the latter cell population are warranted. In this study, we investigated mitochondria as therapeutic target for the development of novel treatment strategies for acetaminophen-induced liver injury. Characterization of the mitochondrial toxicity due to acute acetaminophen overdose ''in vitro'' in human cells using detailed respirometric analysis revealed that Complex I-linked (NADH-dependent) but not Complex II-linked (succinate-dependent) mitochondrial respiration is inhibited by acetaminophen. Treatment with a novel cell-permeable succinate prodrug rescues acetaminophen-induced impaired mitochondrial respiration. This suggests cell-permeable succinate prodrugs as a potential alternative treatment strategy to counteract acetaminophen-induced liver injury.teract acetaminophen-induced liver injury.)
Russell 1991 Am J Physiol + (Acetoacetate, when present as the only fue … Acetoacetate, when present as the only fuel for respiration in rat hearts, causes an impairment in contractile function that is reversible with the addition of substrates that can contribute to anaplerosis. To determine the importance of pyruvate carboxylation via NADP(+)-dependent malic enzyme on metabolism and function in hearts oxidizing acetoacetate, isolated working rat hearts were perfused with [1-14C]pyruvate and acetoacetate. While the cardiac power output after 60 min of perfusion in hearts utilizing acetoacetate alone had fallen to 44% of the initial value, the addition of pyruvate resulted in a stable performance with no fall in the work output. When hydroxymalonate, an inhibitor of NADP(+)-dependent malic enzyme and malate dehydrogenase, was added to the two substrates, function at 60 min was similar to the value for hearts oxidizing acetoacetate alone. Measurements of the specific activities of malate, aspartate, and citrate confirm inhibition of both pyruvate carboxylation and malate oxidation. The findings are consistent with a mechanism in which the enrichment of malate by pyruvate improves function by increasing the production of reducing equivalents by the malate dehydrogenase and the isocitrate dehydrogenase reactions increase flux through the span of the tricarboxylic acid cycle from malate to 2-oxoglutarate. The present study demonstrates the physiological importance of anaplerotic pathways in maintaining contractile function in the heart.taining contractile function in the heart.)
Manko 2013 Acta Physiol (Oxf) + (Acetylcholine as one of the main secretago … Acetylcholine as one of the main secretagogues modulates mitochondrial functions in acinar pancreacytes, presumably due to increase in ATP hydrolysis or Ca2+ transport into mitochondria. The aim of this work was to investigate the mechanisms of carbachol (CCh) action on respiration and oxidative phosphorylation of isolated pancreatic acini.Respiration of intact or permeabilized rat pancreatic acini was studied at 37 °C using a Clark oxygen electrode.Respiration rate of isolated acini in rest was 0.27 ± 0.01 nmol O2 s-1 10-6 cells. Addition of 10 μM CCh into respiration chamber evoked biphasic stimulation of respiration. Rapid increase of respiration by 20.1% lasted for approx. 1 min, followed by decrease to level by 11.5% higher than control. Addition of 1 μm CCh caused monophasic increase by 11.5%. Preincubation (5 min) with 1 or 10 μm CCh elevated respiration rate by 12.5 or 11.2% respectively. FCCP prevented the effect of CCh. Preincubation with 1 (but not 10) μm CCh increased FCCP-uncoupled respiration rate. Thapsigargin slightly elevated respiration, but ryanodine did not. Application of 2-aminoethoxydiphenyl borate or ruthenium red prevented the effects of CCh on respiration, while oligomycin abolished them. Preincubation with 1 μm CCh prior to cell permeabilization increased respiration rate at pyruvate+malate oxidation, but not at succinate oxidation. In contrast, preincubation with 10 μm CCh decreased pyruvate+malate oxidation.Medium CCh dose (1 μm) intensifies respiration and oxidative phosphorylation of acinar pancreacytes by feedforward mechanism via Ca2+ transport into mitochondria and activation of Ca2+ /ADP-sensitive mitochondrial dehydrogenases. Prolonged action of high CCh dose (10 μm) might impair mitochondrial functions.ndrial dehydrogenases. Prolonged action of high CCh dose (10 μm) might impair mitochondrial functions.)
Walker 1970 J Biol Chem + (Acid hydrolysis of flavin peptides from th … Acid hydrolysis of flavin peptides from the active center of mammalian succinate dehydrogenase yields a substituted riboflavin which was isolated in pure form. It contains a substituent attached to position 8a of riboflavin. Drastic acid hydrolysis of this compound and catalytic hydrogenation yield nearly 1 mole of free histidine. Histidine is also liberated on neutral photolysis. The presence of histidine is confirmed by behavior on high voltage electrophoresis at various pH values and by acid titration curves. Linkage of the 8cr-CHs group of riboflavin is to one of the imidazole ring nitrogens since neither the flavin peptide nor its acid derivative give a Pauly reaction. This assignment is in full accord with the characteristic pH-fluorescence curve of covalently bound flavin. The pK of the fluorescence quenching agrees with that expected for the imidazole nitrogen in histidyl flavin.the imidazole nitrogen in histidyl flavin.)
Boushel 2011 Mitochondrion + (Across a wide range of species and body ma … Across a wide range of species and body mass a close matching exists between maximal conductive oxygen delivery and mitochondrial respiratory rate. In this study we investigated in humans how closely ''in vivo'' maximal oxygen consumption (''V''O(2)max) is matched to muscle tissue-specific OXPHOS capacity ([[State 3]]) respiration. High-resolution respirometry was used to quantify mitochondrial respiration from the biopsies of arm and leg muscles while ''in vivo'' arm and leg ''V''O(2) were determined by the Fick method during leg cycling and arm cranking. We hypothesized that muscle mitochondrial respiratory rate exceeds that of systemic oxygen delivery. OXPHOS capacity of the deltoid muscle (4.3±0.4 mmol O(2)kg(-1)min(-1)) was similar to the ''in vivo'' ''V''O(2) during maximal arm cranking (4.7±0.5 mmol O(2)kg(-1)min(-1)) with 6 kg muscle. In contrast, the mitochondrial OXPHOS capacity of the quadriceps was 6.9±0.5 mmol O(2)kg(-1)min(-1), exceeding the ''in vivo'' leg ''V''O(2)max (5.0±0.2mmolO(2)kg(-1)min(-1)) during leg cycling with 20 kg muscle (''P''<0.05). Thus, when half or more of the body muscle mass is engaged during exercise, muscle mitochondrial respiratory capacity surpasses ''in vivo'' ''V''O(2)max. The findings reveal an excess capacity of muscle mitochondrial respiratory rate over O(2) delivery by the circulation in the cascade defining maximal oxidative rate in humans.de defining maximal oxidative rate in humans.)
Mills 2016 Cell + (Activated macrophages undergo metabolic re … Activated macrophages undergo metabolic reprogramming, which drives their pro-inflammatory phenotype, but the mechanistic basis for this remains obscure. Here, we demonstrate that upon lipopolysaccharide (LPS) stimulation, macrophages shift from producing ATP by oxidative phosphorylation to glycolysis while also increasing succinate levels. We show that increased mitochondrial oxidation of succinate via succinate dehydrogenase (SDH) and an elevation of mitochondrial membrane potential combine to drive mitochondrial reactive oxygen species (ROS) production. RNA sequencing reveals that this combination induces a pro-inflammatory gene expression profile, while an inhibitor of succinate oxidation, dimethyl malonate (DMM), promotes an anti-inflammatory outcome. Blocking ROS production with rotenone by uncoupling mitochondria or by expressing the alternative oxidase (AOX) inhibits this inflammatory phenotype, with AOX protecting mice from LPS lethality. The metabolic alterations that occur upon activation of macrophages therefore repurpose mitochondria from ATP synthesis to ROS production in order to promote a pro-inflammatory state.order to promote a pro-inflammatory state.)
Droese 2006 J Biol Chem + (Activation by diazoxide and inhibition by … Activation by diazoxide and inhibition by 5-hydroxydecanoate are the hallmarks of mitochondrial ATP-sensitive K+(KATP) channels. Opening of these channels is thought to trigger cytoprotection (preconditioning) through the generation of reactive oxygen species. However, we found that diazoxide-induced oxidation of the widely used reactive oxygen species indicator 2′,7′-dichlorodihydrofluorescein in isolated liver and heart mitochondria was observed in the absence of ATP or K+ and therefore independent of KATP channels. The response was blocked by stigmatellin, implying a role for the cytochrome ''bc''1 complex (Complex III). Diazoxide, though, did not increase hydrogen peroxide (H2O2) production (quantitatively measured with Amplex Red) in intact mitochondria, submitochondrial particles, or purified cytochrome ''bc''1 complex. We confirmed that diazoxide inhibited succinate oxidation, but it also weakly stimulated State 4 respiration even in K+-free buffer, excluding a role for KATP channels. Furthermore, we have shown previously that 5-hydroxydecanoate is partially metabolized, and we hypothesized that fatty acid metabolism may explain the ability of this putative mitochondrial KATP channel blocker to inhibit diazoxide-induced flavoprotein fluorescence, commonly used as an assay of KATP channel activity. Indeed, consistent with our hypothesis, we found that decanoate inhibited diazoxide-induced flavoprotein oxidation. Taken together, our data question the “mitochondrial KATP channel” hypothesis of preconditioning. Diazoxide did not evoke superoxide (which dismutates to H2O2) from the respiratory chain by a direct mechanism, and the stimulatory effects of this compound on mitochondrial respiration and 2′,7′-dichlorodihydrofluorescein oxidation were not due to the opening of KATP channels.the respiratory chain by a direct mechanism, and the stimulatory effects of this compound on mitochondrial respiration and 2′,7′-dichlorodihydrofluorescein oxidation were not due to the opening of KATP channels.)
Bernhardt 2015 Abstract MiPschool Greenville 2015 + (Activation of mammalian embryonic developm … Activation of mammalian embryonic development relies on a series of fertilization-induced increases in intracellular Ca2+. Full egg activation also requires influx of extracellular Ca2+, but the channel or channels mediating this influx remain unknown. In these studies we examined whether T-type Ca2+ channels, including CACNA1H subunit-containing CaV3.2 channels, mediate Ca2+ entry after fertilization. We found that female mice lacking CACNA1H have reduced litter size. Careful analysis of Ca2+ oscillation patterns following ''in vitro'' fertilization (IVF) of ''Cacna1h-/-'' eggs revealed shortening of the first Ca2+ transient length and reduction in Ca2+ oscillation persistence. Both total and endoplasmic reticulum (ER) Ca2+ stores in ''Cacna1h-/-'' eggs were reduced, showing an impairment of Ca2+ accumulation during oocyte maturation in ''Cacna1h-/-'' eggs. Pharmacological inhibition of T-type channels during ''in vitro'' maturation also reduced Ca2+ store accumulation, indicating that T-type channels are responsible for mediating Ca2+ entry and ER store accumulation during meiotic maturation. T-type channel inhibition also reduced oscillation persistence, frequency, and duration following IVF in wild-type eggs. Together, these data support previously unrecognized roles for T-type Ca2+ channels in mediating the maturation-associated increase in ER Ca2+ stores and allowing Ca2+ influx required for the activation of embryo development. In future studies, we plan to investigate how fluxes in oocyte Ca2+ and Zn2+ influence mitochondrial function, which is a critical determinant of oocyte and embryo quality. Developing better understanding of the interplay between these pathways may translate into clinical application to improve assisted reproductive technologies.;2+ influence mitochondrial function, which is a critical determinant of oocyte and embryo quality. Developing better understanding of the interplay between these pathways may translate into clinical application to improve assisted reproductive technologies.)
Svensson 2017 Acta Physiol (Oxf) + (Activation of the NAD+</sup& … Activation of the NAD+ dependent protein deacetylase SIRT1 has been proposed as a therapeutic strategy to treat mitochondrial dysfunction and insulin resistance in skeletal muscle. However, lifelong overexpression of SIRT1 in skeletal muscle does not improve parameters of mitochondrial function and insulin sensitivity. In this study, we investigated whether temporal overexpression of SIRT1 in muscle of adult mice would affect skeletal muscle mitochondrial function and insulin sensitivity.To circumvent potential effects of germline SIRT1 overexpression, we utilized an inducible model of SIRT1 overexpression in skeletal muscle of adult mice (i-mOX). Insulin sensitivity was assessed by 2-deoxyglucose uptake, muscle maximal respiratory function by high-resolution respirometry and systemic energy expenditure was assessed by whole body calorimetry.Although SIRT1 was highly, and specifically, overexpressed in skeletal muscle of i-mOX compared to WT mice, glucose tolerance and skeletal muscle insulin sensitivity were comparable between genotypes. Additionally, markers of mitochondrial biogenesis, muscle maximal respiratory function and whole-body oxygen consumption were also unaffected by SIRT1 overexpression.These results support previous work demonstrating that induction of SIRT1 in skeletal muscle, either at birth or in adulthood, does not impact muscle insulin action or mitochondrial function.© 2017 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.iological Society. Published by John Wiley & Sons Ltd.)
Magga 2019 Mol Ther + (Activin A and myostatin, members of the tr … Activin A and myostatin, members of the transforming growth factor (TGF)-β superfamily of secreted factors, are potent negative regulators of muscle growth, but their contribution to myocardial ischemia-reperfusion (IR) injury is not known. The aim of this study was to investigate if activin 2B (ACVR2B) receptor ligands contribute to myocardial IR injury. Mice were treated with soluble ACVR2B decoy receptor (ACVR2B-Fc) and subjected to myocardial ischemia followed by reperfusion for 6 or 24 h. Systemic blockade of ACVR2B ligands by ACVR2B-Fc was protective against cardiac IR injury, as evidenced by reduced infarcted area, apoptosis, and autophagy and better preserved LV systolic function following IR. ACVR2B-Fc modified cardiac metabolism, LV mitochondrial respiration, as well as cardiac phenotype toward physiological hypertrophy. Similar to its protective role in IR injury ''in vivo'', ACVR2B-Fc antagonized SMAD2 signaling and cell death in cardiomyocytes that were subjected to hypoxic stress. ACVR2B ligand myostatin was found to exacerbate hypoxic stress. In addition to acute cardioprotection in ischemia, ACVR2B-Fc provided beneficial effects on cardiac function in prolonged cardiac stress in cardiotoxicity model. By blocking myostatin, ACVR2B-Fc potentially reduces cardiomyocyte death and modifies cardiomyocyte metabolism for hypoxic conditions to protect the heart from IR injury.tions to protect the heart from IR injury.)
Benard 2008 Int J Biochem Cell Biol + (Activity defects in respiratory chain comp … Activity defects in respiratory chain complexes are responsible for a large variety of pathological situations, including neuromuscular diseases and multisystemic disorders. Their impact on energy production is highly variable and disproportional. The same biochemical or genetic defect can lead to large differences in clinical symptoms and severity between tissues and patients, making the pathophysiological analysis of mitochondrial diseases difficult. The existence of compensatory mechanisms operating at the level of the respiratory chain might be an explanation for the biochemical complexity observed for respiratory defects. Here, we analyzed the role of cytochrome c and coenzyme Q in the attenuation of complex III and complex IV pharmacological inhibition on the respiratory flux. Spectrophotometry, HPLC-EC, polarography and enzymology permitted the calculation of molar ratios between respiratory chain components, giving values of 0.8:61:3:12:6.8 in muscle and 1:131:3:9:6.5 in liver, for CII:CoQ:CIII:Cyt c:CIV. The results demonstrate the dynamic functional compartmentalization of respiratory chain substrates, with the existence of a substrate pool that can be recruited to maintain energy production at normal levels when respiratory chain complexes are inhibited. The size of this reserve was different between muscle and liver, and in proportion to the magnitude of attenuation of each respiratory defect. Such functional compartmentalization could result from the recently observed physical compartmentalization of respiratory chain substrates. The dynamic nature of the mitochondrial network may modulate this compartmentalization and could play a new role in the control of mitochondrial respiration as well as apoptosis.hondrial respiration as well as apoptosis.)
Soendergaard 2016 Eur J Sport Sci + (Actovegin, a deproteinized haemodialysate … Actovegin, a deproteinized haemodialysate of calf blood, is suggested to have ergogenic properties, but this potential effect has never been investigated in human skeletal muscle. To investigate this purported ergogenic effect, we measured the mitochondrial respiratory capacity in permeabilized human skeletal muscle fibres acutely exposed to Actovegin in a low and in a high dose. We found that Actovegin, in the presence of complex I-linked substrates increased the oxidative phosphorylation (OXPHOS) capacity significantly in a concentration-dependent manner (19 ± 3, 31 ± 4 and 45 ± 4 pmol/mg/s). Maximal OXPHOS capacity with complex I and II-linked substrate was increased when the fibres were exposed to the high dose of Actovegin (62 ± 6 and 77 ± 6 pmol/mg/s) (''p ''< .05). The respiratory capacity of the electron transfer-pathway as well as Vmax and Km were also increased in a concentration-dependent manner after Actovegin exposure (70 ± 6, 79 ± 6 and 88 ± 7 pmol/mg/s; 13 ± 2, 25 ± 3 and 37 ± 4 pmol/mg/s; 0.08 ± 0.02, 0.21 ± 0.03 and 0.36 ± 0.03 mM, respectively) (''p'' < .05). In summary, we report for the first time that Actovegin has a marked effect on mitochondrial oxidative function in human skeletal muscle. Mitochondrial adaptations like this are also seen after a training program in human subjects. Whether this improvement translates into an ergogenic effect in athletes and thus reiterates the need to include Actovegin on the World Anti-Doping Agency's active list remains to be investigated.Agency's active list remains to be investigated.)
Soendergaard 2016 Abstract IOC109 + (Actovegin, a drug made from the deproteini … Actovegin, a drug made from the deproteinized hemodialysate of calf blood increases the mitochondrial respiratory capacity of untrained and overweight subjects, indicating that Actovegin may have the potential to improve performance. These findings are interesting because the drug is not on the World Anti-Doping Agency’s prohibited list, but used by athletes. Therefore, we wanted to investigate whether Actovegin had the same effect in trained subjects. Also, we wanted to compare the effect of Actovegin with the effect of erythropoietin (EPO; a banned substance) on the mitochondrial respiratory capacity. We obtained basal muscle biopsies (''m. vastus lateralis'') from 8 trained subjects (VO2max: 54±2ml/min/kg). The skeletal muscle fibers were acutely exposed to either Actovegin (50µl/ml) or EPO (50µl/ml, 2000IU) during permeabilization, washing of the fibers and the respiratory analysis, resulting in a ~2h exposure time. Mitochondrial respiratory capacity was measured with high-resolution respirometry (Oxygraph-2k; Oroboros , Innsbruck, Austria) and by sequential addition of malate, glutamate, ADP, succinate and FCCP.EPO and Actovegin increased maximal complex I activity (''P''<0.05) compared to control (22±4, 43±3, 61±5pmol/mg/s) with a significant difference between EPO and Actovegin (43±3, 61±5pmol/mg/s, respectively). Only Actovegin increased the maximal oxidative phosphorylation capacity significantly (72±5, 82±8, 95±4pmol/mg/s), but both EPO and Actovegin increased the maximal electron transport system capacity (77±5, 101±9, 112±10pmol/mg/s) (''P''<0.05). In regards to ADP kinetics, Vmax was significantly increased by EPO and Actovegin (18±2, 33±3, 50±4pmol/mg/s) (''P''<0.05), whereas Km was unaltered by EPO, but significantly increased by Actovegin (0.18±0.04, 0.21±0.04, 0.72±0.31mM).The study demonstrates that acute exposure of human muscle fibers to EPO or Actovegin increases the mitochondrial respiratory capacity of trained subjects. The mechanism(s) are not clear, but EPO has been found to increase the NAD+ levels and the NAD+/NADH ratio in myoblasts (1), which could explain the observed increased complex I respiration with EPO (2). Actovegin contains succinate which in part can explain the effect of Actovegin on the mitochondrial respiration. It is not known whether Actovegin also contains NAD+, but it is intriguing to think that Actovegin and EPO might modulate mitochondrial function through the same mechanism, but this is only speculations. the same mechanism, but this is only speculations.)
Arias-Mayenco 2018 Cell Metab + (Acute O2 sensing by … Acute O2 sensing by peripheral chemoreceptors is essential for mammalian homeostasis. Carotid body glomus cells contain O2-sensitive ion channels, which trigger fast adaptive cardiorespiratory reflexes in response to hypoxia. O2-sensitive cells have unique metabolic characteristics that favor the hypoxic generation of mitochondrial complex I (MCI) signaling molecules, NADH and reactive oxygen species (ROS), which modulate membrane ion channels. We show that responsiveness to hypoxia progressively disappears after inducible deletion of the Ndufs2 gene, which encodes the 49 kDa subunit forming the coenzyme Q binding site in MCI, even in the presence of MCII substrates and chemical NAD+ regeneration. We also show contrasting effects of physiological hypoxia on mitochondrial ROS production (increased in the intermembrane space and decreased in the matrix) and a marked effect of succinate dehydrogenase activity on acute O2 sensing. Our results suggest that acute responsiveness to hypoxia depends on coenzyme QH2/Q ratio-controlled ROS production in MCI.esponsiveness to hypoxia depends on coenzyme QH2/Q ratio-controlled ROS production in MCI.)
Stampley 2023 Physiol Rep + (Acute aerobic exercise increases the numbe … Acute aerobic exercise increases the number and proportions of circulating peripheral blood mononuclear cells (PMBC) and can alter PBMC mitochondrial bioenergetics. In this study, we aimed to examine the impact of a maximal exercise bout on immune cell metabolism in collegiate swimmers. Eleven (7 M/4F) collegiate swimmers completed a maximal exercise test to measure anaerobic power and capacity. Pre- and postexercise PBMCs were isolated to measure the immune cell phenotypes and mitochondrial bioenergetics using flow cytometry and high-resolution respirometry. The maximal exercise bout increased circulating levels of PBMCs, particularly in central memory (KLRG1+/CD57-) and senescent (KLRG1+/CD57+) CD8+ T cells, whether measured as a % of PMBCs or as absolute concentrations (all p < 0.05). At the cellularlevel, the routine oxygen flow (IO2 [pmol·s-1 ·106 PBMCs-1 ]) increased following maximal exercise (p = 0.042); however, there were no effects of exercise on the IO2 measured under the LEAK, oxidative phosphorylation (OXPHOS), or electron transfer (ET) capacities. There were exercise-induced increases in the tissue-level oxygen flow (IO2-tissue [pmol·s-1 ·mL blood-1 ]) for all respiratory states (all p < 0.01), except for the LEAK state, after accounting for the mobilization of PBMCs. Future subtype-specific studies are needed to characterize further maximal exercise's true impact on immune cell bioenergetics.zation of PBMCs. Future subtype-specific studies are needed to characterize further maximal exercise's true impact on immune cell bioenergetics.)
Holsgrove 2019 Thesis + (Acute changes in temperature have a signif … Acute changes in temperature have a significant impact on ectotherm metabolic function due to their inability to regulate internal temperatures. An alteration of metabolic rate will drive modulations in cardiac function in order to meet the changing oxygen demands of aerobically active tissues. The function of the fish heart therefore underpins an organisms ability to survive changing temperature. There have been multiple studies assessing the effects of temperature on the metabolism of fish tissue systems but relatively few on the heart. As such, the aims of this thesis were to study the effects of cooling and warming on cardiac metabolism of the rainbow trout. As mitochondria are responsible for producing the majority of ATP for cardiomyocytes and drive aerobic demand, the experiments in this thesis centred on the mitochondrial response to temperature change. In chapter 3, I provide the first thorough investigation into the effect of cold and warm acclimation on cardiac mitochondria morphology in fish. Cold acclimation induced mitochondrial proliferation and an upregulation of mitochondrial fusion, whilst warm acclimation did not increase mitochondrial content but is suggested to increase fission events. A lack of change in internal mitochondrial ultrastructure however doesn't suggest any change in energetic capacity. In chapter 4, I demonstrate that mitochondria are sensitive to acute temperature changes, although their response did not fit expectations. Cold acclimated mitochondria decreased respiratory rates when acutely warmed whilst acute cooling caused an increase in mitochondrial function in warm acclimated fish. This acute response demonstrated a narrowing of the thermal performance window in the cold acclimated fish with warm acclimation shifting the thermal optimum and lowering upper thermal limits. This repression of mitochondrial function may have a significant impact on rainbow trout fitness if exposed to changing temperatures. We found that ROS production was insensitive to temperature changes which may be a result of complex I and III remodelling or due to changes in antioxidant capacity. Metabolic enzymes from the TCA cycle, electron transport chain and fatty acid oxidation pathways demonstrated a limited capacity for remodelling following temperature changes. We show that cold acclimation sensitised metabolic enzymes to acute changes in temperature whilst warm acclimation induced a desensitisation. Cold acclimation did not induce a switch to fatty acid metabolism as might be expected and we demonstrated that citrate synthase is a poor biomarker for mitochondrial content in the rainbow trout heart. Overall, I have shown that the fish heart is sensitive to thermal changes which are reflected functionally and morphologically. Despite being sensitive to temperature changes rainbow trout mitochondria do not fi t traditional compensatory remodelling patterns and instead shift thermal optima. Cold acclimation leads a thermal sensitisation of metabolic enzymes which is not seen in the warm which displayed generally high metabolic activities. This metabolic remodelling may prove to be energetically costly and possibly detrimental to organismal fitness in the wild.imental to organismal fitness in the wild.)
Johansen 2019 Comp Biochem Physiol C Toxicol Pharmacol + (Acute exposure to crude oil and polycyclic … Acute exposure to crude oil and polycyclic aromatic hydrocarbons (PAH) can severely impair cardiorespiratory function and swim performance of larval, juvenile and adult fish. Interestingly, recent work has documented an oil induced decoupling of swim performance (Ucrit) and maximum metabolic rate (MMR) whereby oil causes a decline in Ucrit without a parallel reduction in MMR. We hypothesize that this uncoupling is due to impaired mitochondrial function in swimming muscles that results in increased proton leak, and thus less ATP generated per unit oxygen. Using high resolution mitochondrial respirometry, we assessed 11 metrics of mitochondrial performance in red and cardiac muscle from permeabilized fibers isolated from red drum following control or 24 h crude oil (high energy water accommodated fractions) exposure. Two experimental series were performed, a Deepwater Horizon relevant low dose (29.6 ± 7.4 μg L-1 ∑PAH50) and a proof-of-concept high dose (64.5 ± 8.9 μg L-1 ∑PAH50). No effects were observed on any mitochondrial parameter in either tissue at the low oil dose; however, high dose exposure provided evidence of impairment in the OXPHOS respiratory control ratio and OXPHOS spare capacity in red muscle following oil exposure, as well as a shift from Complex I to Complex II during OXPHOS respiration. No effects of the high dose oil treatment were observed in cardiac muscle. As such, mitochondrial dysfunction is unlikely to be the underlying mechanism for decoupling of Ucrit and MMR following acute oil exposure in red drum. Furthermore, mitochondrial dysfunction does not appear to be a relevant toxicological impairment in juvenile red drum with respect to the Deepwater Horizon oil spill, although impairments may be observed under higher dose exposure scenarios.Copyright © 2019 Elsevier Inc. All rights reserved. 2019 Elsevier Inc. All rights reserved.)
Banh 2015 Comp Biochem Physiol B Biochem Mol Biol + (Acute heat challenge is known to induce ce … Acute heat challenge is known to induce cell-level oxidative stress in fishes. Mitochondria are well known for the capacity to make reactive oxygen species (ROS) and as such are often implicated as a source of the oxidants associated with this thermally-induced oxidative stress. This implication is often asserted, despite little direct data for mitochondrial ROS metabolism in fishes. Here we characterize mitochondrial ROS metabolism in three Actinopterygian fish species at two levels, the capacity for superoxide/H2O2 production and the antioxidant thiol-reductase enzyme activities. We find that red muscle mitochondria from all three species have measurable ROS production and respond to different assay conditions consistent with what might be anticipated; assuming similar relative contributions from difference ROS producing sites as found in rat skeletal muscle mitochondria. Although there are species and assay specific exceptions, fish mitochondria may have a greater capacity to produce ROS than that found in the rat when either normalized to respiratory capacity or determined at a common assay temperature. The interspecific differences in ROS production are not correlated with thiol-based antioxidant reductase activities. Moreover, mimicking an acute ''in vivo'' heat stress by comparing the impact of increasing assay temperature on these processes in vitro, we find evidence supporting a preferential activation of mitochondrial H2O2 production relative to the increase in the capacity of reductase enzymes to supply electrons to the mitochondrial matrix peroxidases. This supports the contention that mitochondria may be, at least in part, responsible for the ROS that lead to oxidative stress in fish tissues exposed to acute heat challenge.for the ROS that lead to oxidative stress in fish tissues exposed to acute heat challenge.)
Calbet 2003 Am J Physiol Regul Integr Comp Physiol + (Acute hypoxia (AH) reduces maximal O<su … Acute hypoxia (AH) reduces maximal O2 consumption (''V''O2max), but after acclimatization, and despite increases in both hemoglobin concentration and arterial O2 saturation that can normalize arterial O2 concentration ([O2]), ''V''O2max remains low. To determine why, seven lowlanders were studied at ''V''O2max (cycle ergometry) at sea level (SL), after 9-10 wk at 5260 m [chronic hypoxia (CH)], and 6 mo later at SL in AH (''F''iO2 = 0.105) equivalent to 5260 m. Pulmonary and leg indexes of O2 transport were measured in each condition. Both cardiac output and leg blood flow were reduced by approximately 15 % in both AH and CH (''P'' < 0.05). At maximal exercise, arterial [O2] in AH was 31 % lower than at SL (''P'' < 0.05), whereas in CH it was the same as at SL due to both polycythemia and hyperventilation. O2 extraction by the legs, however, remained at SL values in both AH and CH. Although at both SL and in AH, 76 % of the cardiac output perfused the legs, in CH the legs received only 67 %. Pulmonary ''V''O2max (4.1 +/- 0.3 L/min at SL) fell to 2.2 +/- 0.1 L/min in AH (''P'' < 0.05) and was only 2.4 +/- 0.2 L/min in CH (''P'' < 0.05). These data suggest that the failure to recover ''V''O2max after acclimatization despite normalization of arterial [O2] is explained by two circulatory effects of altitude: 1) failure of cardiac output to normalize and 2) preferential redistribution of cardiac output to nonexercising tissues. Oxygen transport from blood to muscle mitochondria, on the other hand, appears unaffected by CH.t;sub>2] is explained by two circulatory effects of altitude: 1) failure of cardiac output to normalize and 2) preferential redistribution of cardiac output to nonexercising tissues. Oxygen transport from blood to muscle mitochondria, on the other hand, appears unaffected by CH.)
Wu 2007 Am J Physiol Lung Cell Mol Physiol + (Acute hypoxia causes pulmonary vasoconstri … Acute hypoxia causes pulmonary vasoconstriction and coronary vasodilation. The divergent effects of hypoxia on pulmonary and coronary vascular smooth muscle cells suggest that the mechanisms involved in oxygen sensing and downstream effectors are different in these two types of cells. Since production of reactive oxygen species (ROS) is regulated by oxygen tension, ROS have been hypothesized to be a signaling mechanism in hypoxia-induced pulmonary vasoconstriction and vascular remodeling. Furthermore, an increased ROS production is also implicated in arteriosclerosis. In this study, we determined and compared the effects of hypoxia on ROS levels in human pulmonary arterial smooth muscle cells (PASMC) and coronary arterial smooth muscle cells (CASMC). Our results indicated that acute exposure to hypoxia (Po(2) = 25-30 mmHg for 5-10 min) significantly and rapidly decreased ROS levels in both PASMC and CASMC. However, chronic exposure to hypoxia (Po(2) = 30 mmHg for 48 h) markedly increased ROS levels in PASMC, but decreased ROS production in CASMC. Furthermore, chronic treatment with endothelin-1, a potent vasoconstrictor and mitogen, caused a significant increase in ROS production in both PASMC and CASMC. The inhibitory effect of acute hypoxia on ROS production in PASMC was also accelerated in cells chronically treated with endothelin-1. While the decreased ROS in PASMC and CASMC after acute exposure to hypoxia may reflect the lower level of oxygen substrate available for ROS production, the increased ROS production in PASMC during chronic hypoxia may reflect a pathophysiological response unique to the pulmonary vasculature that contributes to the development of pulmonary vascular remodeling in patients with hypoxia-associated pulmonary hypertension.hypoxia-associated pulmonary hypertension.)
Cortes 2023 Nat Commun + (Acute inflammation can either resolve thro … Acute inflammation can either resolve through immunosuppression or persist, leading to chronic inflammation. These transitions are driven by distinct molecular and metabolic reprogramming of immune cells. The anti-diabetic drug Metformin inhibits acute and chronic inflammation through mechanisms still not fully understood. Here, we report that the anti-inflammatory and reactive-oxygen-species-inhibiting effects of Metformin depend on the expression of the plasticity factor ZEB1 in macrophages. Using mice lacking Zeb1 in their myeloid cells and human patient samples, we show that ZEB1 plays a dual role, being essential in both initiating and resolving inflammation by inducing macrophages to transition into an immunosuppressed state. ZEB1 mediates these diverging effects in inflammation and immunosuppression by modulating mitochondrial content through activation of autophagy and inhibition of mitochondrial protein translation. During the transition from inflammation to immunosuppression, Metformin mimics the metabolic reprogramming of myeloid cells induced by ZEB1. Mechanistically, in immunosuppression, ZEB1 inhibits amino acid uptake, leading to downregulation of mTORC1 signalling and a decrease in mitochondrial translation in macrophages. These results identify ZEB1 as a driver of myeloid cell metabolic plasticity, suggesting that targeting its expression and function could serve as a strategy to modulate dysregulated inflammation and immunosuppression.ulated inflammation and immunosuppression.)
Tretter 2014 Abstract MiP2014 + (Acute ischemia-reperfusion injury of the b … Acute ischemia-reperfusion injury of the brain affects millions of people. Currently there is no really efficient neuroprotective therapy, however, a simple physical procedure, therapeutic hypothermia, can have beneficial effects. Although there is agreement that in this group of diseases oxidative stress is an important factor, the effects of temperature changes on the reactive oxygen species (ROS) formation and on the ROS elimination have not been clarified yet. A few publications in high profile journals claimed that mitochondrial ROS formation was inversely related to increasing temperature. In the present work, the effects of temperature changes on H2O2 formation and elimination were investigated in isolated guinea pig brain mitochondria in association with oxygen consumption.Mitochondrial ROS production was measured using Amplex UltraRed fluorescence, the rate of H2O2 elimination was measured using a hydrogen peroxide-sensitive electrode (WPI). Oxygen consumption of mitochondria was measured using an Oroboros Oxygraph-2k. In order to energize mitochondria glutamate plus malate, succinate and alpha-glycerophosphate substrates were used. The bioenergetic and ROS parameters of mitochondria were investigated at 33, 37 and 41 °C.The rate of substrate oxidation showed a strong increase with temperature, whereas the efficiency of oxidation was decreased. Considering the ROS homeostasis both the formation of H2O2 and the elimination of H2O2 became faster with increasing temperature. With Complex I substrates at resting respiration, H2O2 production was increased by 31%, as a consequence of elevating the temperature from 33 °C to 41 °C. Using succinate or alpha-glycerophosphate, results were similar. The biggest difference (59% between 33 °C and 41 °C) was detected when H2O2 production was measured in the presence of the Complex I inhibitor rotenone. The rate of H2O2 elimination was also elevated by 24% with increased temperature (from 33 °C to 41 °C), in glutamate+malate supported mitochondria. Rising the temperature from hypothermic to hyperthermic conditions resulted in an increase in mitochondrial oxygen consumption, H2O2 production and H2O2 elimination. The increase of ROS production was higher than that of H2O2 elimination; thus, according to our results, the elevation of temperature created oxidative stress conditions. We conclude that the neuroprotective effects of therapeutic hypothermia are also based on the decreased rate of mitochondrial H2O2 production.ub> elimination; thus, according to our results, the elevation of temperature created oxidative stress conditions. We conclude that the neuroprotective effects of therapeutic hypothermia are also based on the decreased rate of mitochondrial H2O2 production.)
Lopes 2022 Int J Mol Sci + (Acute kidney injury (AKI) caused by ischem … Acute kidney injury (AKI) caused by ischemia followed by reperfusion (I/R) is characterized by intense anion superoxide (O2•-) production and oxidative damage. We investigated whether extracellular vesicles secreted by adipose tissue mesenchymal cells (EVs) administered during reperfusion can suppress the exacerbated mitochondrial O2•- formation after I/R. We used Wistar rats subjected to bilateral renal arterial clamping (30 min) followed by 24 h of reperfusion. The animals received EVs (I/R + EVs group) or saline (I/R group) in the kidney subcapsular space. The third group consisted of false-operated rats (SHAM). Mitochondria were isolated from proximal tubule cells and used immediately. Amplex Red™ was used to measure mitochondrial O2•- formation and MitoTracker™ Orange to evaluate inner mitochondrial membrane potential (Δψ). ''In vitro'' studies were carried out on human renal proximal tubular cells (HK-2) co-cultured or not with EVs under hypoxic conditions. Administration of EVs restored O2•- formation to SHAM levels in all mitochondrial functional conditions. The gene expression of catalase and superoxide dismutase-1 remained unmodified; transcription of heme oxygenase-1 (HO-1) was upregulated. The co-cultures of HK-2 cells with EVs revealed an intense decrease in apoptosis. We conclude that the mechanisms by which EVs favor long-term recovery of renal structures and functions after I/R rely on a decrease of mitochondrial O2•- formation with the aid of the upregulated antioxidant HO-1/Nuclear factor erythroid 2-related factor 2 system, thus opening new vistas for the treatment of AKI.; formation with the aid of the upregulated antioxidant HO-1/Nuclear factor erythroid 2-related factor 2 system, thus opening new vistas for the treatment of AKI.)
Patil 2014 Am J Physiol Renal Physiol + (Acute kidney injury (AKI) is a complicatio … Acute kidney injury (AKI) is a complication of sepsis and leads to a high mortality rate. Human and animal studies suggest that mitochondrial dysfunction plays an important role in sepsis-induced multi-organ failure; however, the specific mitochondrial targets damaged during sepsis remain elusive. We used a clinically relevant cecal ligation and puncture (CLP) murine model of sepsis and assessed renal mitochondrial function using high-resolution respirometry, renal microcirculation using intravital microscopy and renal function. CLP caused a time-dependent decrease in mitochondrial complex I and II/III respiration and reduced ATP. By 4 hours after CLP, activity of manganese superoxide dismutase (MnSOD) was decreased by 50% and inhibition was sustained through 36 hours. These events were associated with increased mitochondrial superoxide generation. We then evaluated whether the mitochondria-targeted antioxidant Mito-TEMPO could reverse renal mitochondrial dysfunction and attenuate sepsis-induced AKI. Mito-TEMPO (10 mg/kg) given at 6 hours post CLP decreased mitochondrial superoxide levels, protected complex I and II/III respiration, and restored MnSOD activity by 18 hours. Mito-TEMPO also improved renal microcirculation and glomerular filtration rate. Importantly, even delayed therapy with a single dose of Mito-TEMPO significantly increased 96-hour survival rate from 40% in untreated septic mice to 80%. Thus, sepsis causes sustained inactivation of three mitochondrial targets that can lead to increased mitochondrial superoxide. Importantly, even delayed therapy with Mito-TEMPO alleviated kidney injury, suggesting that it may be a promising approach to treat septic AKI. a promising approach to treat septic AKI.)
Quoilin 2014 Dissertation + (Acute kidney injury (AKI) is a frequent co … Acute kidney injury (AKI) is a frequent complication of sepsis that can increase mortality as high as 70%. The pathophysiology of this kidney failurewas previously believed to be secondary to decreased global renal perfusion causing hypoxia-induced injury. However, new research suggests this paradigm is overly simplistic, and injury is now considered multifactorial in origin. Mechanisms that contribute to kidney injury mainly include inflammation, alterations in microvascular renal blood flow and changes in bioenergetics.To study the mechanism of oxygen regulation in acute kidney injury during sepsis, we developed a sepsis-induced ''in vitro'' model using proximal tubular epithelial cells (HK-2) exposed to a bacterial endotoxin (lipopolysaccharide, LPS). Our first investigation, by using both high-resolution respirometry and electron spin resonance spectroscopy, showed that HK-2 cells exhibit a decreased oxygen consumption rate when treated with LPS. Surprisingly,this cellular respiration alteration persists even after the stress factor is removed. We suggested that this irreversible decrease in renal oxygen consumption after LPS challenge is related to a pathologic metabolic down-regulation such as a lack of oxygen utilization by cells for ATP production. In the long term, this metabolic disturbance leads cells to a predominantlyapoptotic death. cells to a predominantly apoptotic death.)
Li 2022 Mol Med + (Acute kidney injury (AKI) is still a criti … Acute kidney injury (AKI) is still a critical problem in clinical practice, with a heavy burden for national health system around the world. It is notable that sepsis is the predominant cause of AKI for patients in the intensive care unit and the mortality remains considerably high. The treatment for AKI relies on supportive therapies and almost no specific treatment is currently available. Spermidine is a naturally occurring polyamine with pleiotropic effects. However, the renoprotective effect of spermidine and the underlying mechanism remain elusive.We employed mice sepsis-induced AKI model and explored the potential renoprotective effect of spermidine ''in vivo'' with different administration time and routes. Macrophage depleting was utilized to probe the role of macrophage. ''In vitro'' experiments were conducted to examine the effect of spermidine on macrophage cytokine secretion, NLRP3 inflammasome activation and mitochondrial respiration.We confirmed that spermidine improves AKI with different administration time and routes and that macrophages serves as an essential mediator in this protective effect. Meanwhile, spermidine downregulates NOD-like receptor protein 3 (NLRP3) inflammasome activation and IL-1 beta production in macrophages directly. Mechanically, spermidine enhances mitochondrial respiration capacity and maintains mitochondria function which contribute to the NLRP3 inhibition. Importantly, we showed that eukaryotic initiation factor 5A (eIF5A) hypusination plays an important role in regulating macrophage bioactivity.Spermidine administration practically protects against sepsis-induced AKI in mice and macrophages serve as an essential mediator in this protective effect. Our study identifies spermidine as a promising pharmacologic approach to prevent AKI.ing pharmacologic approach to prevent AKI.)
Zhang 2019 Biochem Biophys Res Commun + (Acute liver injury seriously endangers hum … Acute liver injury seriously endangers human health. Liraglutide, a glucagon-like peptide-1 (GLP-1) analogue, has antioxidative effects in addition to being widely used in the treatment of type 2 diabetes and was reported to ameliorate liver diseases. The aim of this study was to evaluate the hepatoprotective effects of liraglutide on carbon tetrachloride (CCl4)-induced acute liver injury in mice and to investigate the mechanisms involved in this protective effect. Male BALB/c mice were pre-treated with liraglutide (200 μg/kg/day) by hypodermic injection for 3 days before a 0.1% (v/v) CCl4 (10 ml/kg, dissolved in olive oil) intraperitoneal injection, or post-treated with liraglutide once immediately after a CCl4 intraperitoneal injection. The experimental data showed that liraglutide treatment significantly decreased the serum ALT and AST levels and ameliorated the liver histopathological changes induced by CCl4. In addition, liraglutide pre-treatment dramatically increased the number of proliferating cell nuclear antigen (PCNA)-positive hepatocytes and significantly reduced hepatocyte apoptosis after CCl4 treatment. As a consequence, liraglutide pre-treatment significantly prevented CCl4-induced malondialdehyde (MDA) production and increased the activity of the antioxidant superoxide dismutase (SOD) enzyme. In addition, liraglutide pre-treatment significantly ameliorated mitochondrial respiratory functions and ultrastructural features. Furthermore, liraglutide pre-treatment enhances the activation of the NRF2/HO-1 signaling pathway. In summary, liraglutide protects against CCl4-induced acute liver injury by protecting mitochondrial functions and inhibiting oxidative stress, which may partly involve the activation of NRF2/HO-1 signaling pathway.Copyright © 2019 Elsevier Inc. All rights reserved. 2019 Elsevier Inc. All rights reserved.)
Canevarolo 2017 Thesis + (Acute lymphoblastic leukemia (ALL) is the … Acute lymphoblastic leukemia (ALL) is the most common type of childhood cancer, accounting for 25% of all cancers in this age group. One of the chemotherapeutics used in the therapy of ALL (and autoimmune diseases such as rheumatoid arthritis) is methotrexate (MTX), a folic acid antagonist (antifolate). As a chemotherapeutic agent, MTX´s mechanism of action is primarily attributed to the inhibition of the dihydrophate reductase enzyme, which synthesizes tetrahydrofolate from dihydrofolate – a key step in the ''de novo'' synthesis of purine nucleotides used in cell division. In rheumatoid arthritis, lower doses of MTX inhibit the 5-aminoimidazole-4-ribonucleotide-carboxamide formyltransferase (ATIC) enzyme, which culminates in the production of high levels of adenosine, a potent anti-inflammatory. However, recent works continue to present previously unknown mechanisms and effects through which MTX acts within the cell, attesting that MTX´s mechanisms of action appear to be as multiple as complex. Using several techniques of molecular biology, this work sought to expand the existing knowledge of the action of MTX in ALL. For this purpose, severalbiological parameters were measured under or without MTX treatment in a panel of 13 ALLcell lines. Proliferation tests, metabolic studies, drug synergism, quantification of cellularrespiration and the production of reactive oxygen species (ROS) were performed, as well asthe measurement of the activation of the NF-κB signaling pathway. Resistance of the MTXstrains within 48 h of treatment (but not 96 h) was related to the proliferation rate of the cells.Treatment with MTX altered the concentration of 28 intracellular metabolites, highlights for aconsistent increase in glycine concentration. Intracellular concentrations of asparagine,guanosine and glutathione – including the expression of genes from glutathione pathway –were associated with MTX resistance. Supplementation of the culture medium with Nacetylcysteine,a precursor metabolite of glutathione, promoted proliferation and resistance toMTX; however, cell treatment with piperlongumine or hydrogen peroxide, two glutathionescavengers and ROS promoters, did not potentiate the effect of MTX. MTX induced ROS inALL after 6 h of treatment with low fold change, though. Paradoxically, higher ROSproduction was found in cell lines with high MTX resistance and intracellular glutathione.The oxygen uptake of the cell lines was not associated with MTX resistance and a preliminarytest showed that MTX did not alter cellular respiration. MTX activated the transcription factorNF-κB in some ALL cell lines and, interestingly, the activation of this transcription factor bytumor necrosis factor alpha (TNF-α) was positively correlated with the resistance of leukemiclines to MTX. A wide bibliographic review allowed both the integration of the obtainedresults to the most current knowledge on the subject, and the identification of new paths to beexplored in future stages.new paths to be explored in future stages.)
Warren 2017 Metabolism + (Acute metabolic demands that promote exces … Acute metabolic demands that promote excessive and/or prolonged reactive oxygen species production may stimulate changes in mitochondrial oxidative capacity.To assess changes in skeletal muscle H2O2 production, mitochondrial function, and expression of genes at the mRNA and protein levels regulating energy metabolism and mitochondrial dynamics following a hyperinsulinemic-euglycemic clamp in a cohort of 11 healthy premenopausal women.Skeletal muscle biopsies of the vastus lateralis were taken at baseline and immediately following the conclusion of a hyperinsulinemic-euglycemic clamp. Mitochondrial production of H2O2 was quantified fluorometrically and mitochondrial oxidation supported by pyruvate, malate, and succinate (PMS) or palmitoyl carnitine and malate (PCM) was measured by high-resolution respirometry in permeabilized muscle fiber bundles. mRNA and protein levels were assessed by real time PCR and Western blotting.H2O2 emission increased following the clamp (P<0.05). Coupled respiration (State 3) supported by PMS and the respiratory control ratio (index of mitochondrial coupling) for both PMS and PCM were lower following the clamp (P<0.05). IRS1 mRNA decreased, whereas PGC1α and GLUT4 mRNA increased following the clamp (P≤0.05). PGC1α, IRS1, and phosphorylated AKT protein levels were higher after the clamp compared to baseline (P<0.05).This study demonstrated that acute hyperinsulinemia induced H2O2 production and a concurrent decrease in coupling of mitochondrial respiration with ATP production in a cohort of healthy premenopausal women. Future studies should determine if this uncoupling ameliorates peripheral oxidative damage, and if this mechanism is impaired in diseases associated with chronic oxidative stress.Copyright © 2017 Elsevier Inc. All rights reserved.amage, and if this mechanism is impaired in diseases associated with chronic oxidative stress. Copyright © 2017 Elsevier Inc. All rights reserved.)
Bailey 2001 High Alt Med Biol + (Acute mountain sickness; prophylactic bene … Acute mountain sickness; prophylactic benefits of Free-radical-mediated damage to the blood-brain barrier may be implicated in the pathophysiology of acute mountain sickness (AMS). To indirectly examine this, we conducted a randomized double-blind placebo-controlled trial to assess the potentially prophylactic benefits of enteral antioxidant vitamin supplementation during ascent to high altitude. Eighteen subjects aged 35 +/- 10 years old were randomly assigned double-blind to either an antioxidant (n = 9) or placebo group (n = 9). The antioxidant group ingested 4 capsules/day(-1) (2 after breakfast/2 after evening meal) that each contained 250 mg of L-ascorbic acid, 100 IU of dl-a-tocopherol acetate and 150 mg of alpha-lipoic acid. The placebo group ingested 4 capsules of identical external appearance, taste, and smell. Supplementation was enforced for 3 weeks at sea level and during a 10-day ascent to Mt. Everest base camp (approximately 5,180 m). Antioxidant supplementation resulted in a comparatively lower Lake Louise AMS score at high altitude relative to the placebo group (2.8 +/- 0.8 points versus 4.0 +/- 0.4 points, P = 0.036), higher resting arterial oxygen saturation (89 +/- 5% versus 85 +/- 5%, P = 0.042), and total caloric intake (13.2 +/- 0.6 MJ/day(-1) versus 10.1 +/- 0.7 MJ/day(-1), P = 0.001); the latter is attributable to a lower satiety rating following a standardized meal. These findings indicate that the exogenous provision of water and lipid-soluble antioxidant vitamins at the prescribed doses is an apparently safe and potentially effective intervention that can attenuate AMS and improve the physiological profile of mountaineers at high altitude. profile of mountaineers at high altitude.)
Fisher-Wellman 2023 Cancers (Basel) + (Acute myelogenous leukemia (AML), the most … Acute myelogenous leukemia (AML), the most prevalent acute and aggressive leukemia diagnosed in adults, often recurs as a difficult-to-treat, chemotherapy-resistant disease. Because chemotherapy resistance is a major obstacle to successful treatment, novel therapeutic intervention is needed. Upregulated ceramide clearance via accelerated hydrolysis and glycosylation has been shown to be an element in chemotherapy-resistant AML, a problem considering the crucial role ceramide plays in eliciting apoptosis. Herein we employed agents that block ceramide clearance to determine if such a "reset" would be of therapeutic benefit. SACLAC was utilized to limit ceramide hydrolysis, and D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-threo-PDMP) was used to block the glycosylation route. The SACLAC D-threo-PDMP inhibitor combination was synergistically cytotoxic in drug-resistant, P-glycoprotein-expressing (P-gp) AML but not in wt, P-gp-poor cells. Interestingly, P-gp antagonists that can limit ceramide glycosylation via depression of glucosylceramide transit also synergized with SACLAC, suggesting a paradoxical role for P-gp in the implementation of cell death. Mechanistically, cell death was accompanied by a complete drop in ceramide glycosylation, concomitant, striking increases in all molecular species of ceramide, diminished sphingosine 1-phosphate levels, resounding declines in mitochondrial respiratory kinetics, altered Akt, pGSK-3β, and Mcl-1 expression, and caspase activation. Although ceramide was generated in wt cells upon inhibitor exposure, mitochondrial respiration was not corrupted, suggestive of mitochondrial vulnerability in the drug-resistant phenotype, a potential therapeutic avenue. The inhibitor regimen showed efficacy in an ''in vivo'' model and in primary AML cells from patients. These results support the implementation of SL enzyme targeting to limit ceramide clearance as a therapeutic strategy in chemotherapy-resistant AML, inclusive of a novel indication for the use of P-gp antagonists.ndication for the use of P-gp antagonists.)
Peng 2022 Front Oncol + (Acute myeloid leukemia (AML) is a heteroge … Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy characterized by multiple cytogenetic and molecular abnormalities, with a very poor prognosis. Current treatments for AML often fail to eliminate leukemic stem cells (LSCs), which perpetuate the disease. LSCs exhibit a unique metabolic profile, especially dependent on oxidative phosphorylation (OXPHOS) for energy production. Whereas, normal hematopoietic stem cells (HSCs) and leukemic blasts rely on glycolysis for adenosine triphosphate (ATP) production. Thus, understanding the regulation of OXPHOS in LSCs may offer effective targets for developing clinical therapies in AML. This review summarizes these studies with a focus on the regulation of the electron transport chain (ETC) and tricarboxylic acid (TCA) cycle in OXPHOS and discusses potential therapies for eliminating LSCs. potential therapies for eliminating LSCs.)
Jayasankar 2022 ACS Omega + (Acute myeloid leukemia (AML) is an aggress … Acute myeloid leukemia (AML) is an aggressive blood cancer with limited effective chemotherapy options and negative patient outcomes. Food-derived molecules such as avocatin B (Avo B), a fatty-acid oxidation (FAO) inhibitor, are promising novel therapeutics. The roots of the Curcuma amada plants have been historically used in traditional medicine, but isolated bioactive compounds have seldom been studied. Here, we report that 2,4,6-trihydroxy-3,5-diprenyldihydrochalcone (M1), a bioactive from C. Amada, possesses novel anticancer activity. This in vitro study investigated the antileukemia properties of M1 and its effects on mitochondrial metabolism. In combination with Avo B, M1 synergistically reduced AML cell line viability and patient-derived clonogenic growth with no effect on normal peripheral blood stem cells. Mechanistically, M1 alone inhibited mitochondria complex I, while the M1/Avo B combination inhibited FAO by 60 %, a process essential to the synergy. These results identified a novel food-derived bioactive and its potential as a novel chemotherapeutic for AML.ntial as a novel chemotherapeutic for AML.)
Maeda 2020 J Cell Mol Med + (Acute myocardial infarction is a leading c … Acute myocardial infarction is a leading cause of death among single organ diseases. Despite successful reperfusion therapy, ischaemia reperfusion injury (IRI) can induce oxidative stress (OS), cardiomyocyte apoptosis, autophagy and release of inflammatory cytokines, resulting in increased infarct size. In IRI, mitochondrial dysfunction is a key factor, which involves the production of reactive oxygen species, activation of inflammatory signalling cascades or innate immune responses, and apoptosis. Therefore, intercellular mitochondrial transfer could be considered as a promising treatment strategy for ischaemic heart disease. However, low transfer efficiency is a challenge in clinical settings. We previously reported uptake of isolated exogenous mitochondria into cultured cells through co-incubation, mediated by macropinocytosis. Here, we report the use of transactivator of transcription dextran complexes (TAT-dextran) to enhance cellular uptake of exogenous mitochondria and improve the protective effect of mitochondrial replenishment in neonatal rat cardiomyocytes (NRCMs) against OS. TAT-dextran-modified mitochondria (TAT-Mito) showed a significantly higher level of cellular uptake. Mitochondrial transfer into NRCMs resulted in anti-apoptotic capability and prevented the suppression of oxidative phosphorylation in mitochondria after OS. Furthermore, TAT-Mito significantly reduced the apoptotic rates of cardiomyocytes after OS, compared to simple mitochondrial transfer. These results indicate the potential of mitochondrial replenishment therapy in OS-induced myocardial IRI.© 2020 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.ular Medicine and John Wiley & Sons Ltd.)
Roy 2016 Free Radic Biol Med + (Acute myocardial infarction leads to an in … Acute myocardial infarction leads to an increase in oxidative stress and lipid peroxidation. 4(RS)-4-F4t-Neuroprostane (4-F4t-NeuroP) is a mediator produced by non-enzymatic free radical peroxidation of the cardioprotective polyunsaturated fatty acid, docosahexaenoic acid (DHA). In this study, we investigated whether intra-cardiac delivery of 4-F4t-NeuroP (0.03mg/kg) prior to occlusion (ischemia) prevents and protects rat myocardium from reperfusion damages. Using a rat model of ischemic-reperfusion (I/R), we showed that intra-cardiac infusion of 4-F4t-NeuroP significantly decreased infarct size following reperfusion (-27%) and also reduced ventricular arrhythmia score considerably during reperfusion (-41%). Most notably, 4-F4t-NeuroP decreased ventricular tachycardia and post-reperfusion lengthening of QT interval. The evaluation of the mitochondrial homeostasis indicates a limitation of mitochondrial swelling in response to Ca2+ by decreasing the mitochondrial permeability transition pore opening and increasing mitochondria membrane potential. On the other hand, mitochondrial respiration measured by oxygraphy, and mitochondrial ROS production measured with MitoSox red® were unchanged. We found decreased cytochrome ''c'' release and caspase 3 activity, indicating that 4-F4t-NeuroP prevented reperfusion damages and reduced apoptosis. In conclusion, 4-F4t-NeuroP derived from DHA was able to protect I/R cardiac injuries by regulating the mitochondrial homeostasis.Copyright © 2016 Elsevier Inc. All rights reserved.. Copyright © 2016 Elsevier Inc. All rights reserved.)
Ohsawa 2007 Nat Med + (Acute oxidative stress induced by ischemia … Acute oxidative stress induced by ischemia-reperfusion or inflammation causes serious damage to tissues, and persistent oxidative stress is accepted as one of the causes of many common diseases including cancer. We show here that hydrogen (H2) has potential as an antioxidant in preventive and therapeutic applications. We induced acute oxidative stress in cultured cells by three independent methods. H2 selectively reduced the hydroxyl radical, the most cytotoxic of reactive oxygen species (ROS), and effectively protected cells; however, H2 did not react with other ROS, which possess physiological roles. We used an acute rat model in which oxidative stress damage was induced in the brain by focal ischemia and reperfusion. The inhalation of H2 gas markedly suppressed brain injury by buffering the effects of oxidative stress. Thus H2 can be used as an effective antioxidant therapy; owing to its ability to rapidly diffuse across membranes, it can reach and react with cytotoxic ROS and thus protect against oxidative damage.across membranes, it can reach and react with cytotoxic ROS and thus protect against oxidative damage.)
Mikami 2019 Can J Physiol Pharmacol + (Acute physical exercise increases reactive … Acute physical exercise increases reactive oxygen species in skeletal muscle, leading to tissue damage and fatigue. Molecular hydrogen (H2) acts as a therapeutic antioxidant directly or indirectly by inducing antioxidative enzymes. Here, we examined the effects of drinking H2 water (H2-infused water) on psychometric fatigue and endurance capacity in a randomized, double-blind, placebo-controlled fashion. In Experiment 1, all participants drank only placebo water in the first cycle ergometer exercise session, and for comparison they drank either H2 water or placebo water 30 min before exercise in the second examination. In these healthy non-trained participants (''N'' = 99), psychometric fatigue judged by visual analogue scales was significantly decreased in the H2 group after mild exercise. When each group was divided into 2 subgroups, the subgroup with higher visual analogue scale values was more sensitive to the effect of H2. In Experiment 2, trained participants (''N'' = 60) were subjected to moderate exercise by cycle ergometer in a similar way as in Experiment 1, but exercise was performed 10 min after drinking H2 water. Endurance and fatigue were significantly improved in the H2 group as judged by maximal oxygen consumption and Borg's scale, respectively. Taken together, drinking H2 water just before exercise exhibited anti-fatigue and endurance effects.ibited anti-fatigue and endurance effects.)
Hoppel 2015 Abstract MiP2015 + (Acute strenuous exercise is linked to seve … Acute strenuous exercise is linked to severe inflammatory responses [1,2], alterations of mitochondrial function of human skeletal muscle and increased oxidative stress [3]. Due to the invasive nature of muscle biopsies, minimally-invasive alternatives to study mitochondrial function in tissues such as blood cells are gaining significance. Mitochondrial function in human platelets and lymphocytes has been characterized in various disease states. Importantly, respiratory capacity of human PBMCs was linked to physical fitness [4], supporting the concept that mitochondrial function in human blood cells can be used as a systemic mitochondrial marker. In this study we investigated the influence of completion of an ultramarathon on mitochondrial respiration in human platelets.After informed consent, 10 male recreational athletes (mean age: 39.9 yrs; BMI 24.9 kg2/m) who participated in a competition over 67 km and approximately 4,500 m ascent, were included in the study. Baseline (PRE) measurements were performed on the day before the competition and follow-up sampling was performed within 15 min after finishing the race (POST) by sampling whole blood. To address potential effects of recovery, a third time point was selected 24 h after finishing (REC). Evaluation of mitochondrial respiration was conducted in freshly purified human platelets by the use of six Oroboros Oxygraph-2k operating in parallel. ROUTINE respiration (R), Complex I-linked LEAK and OXPHOS capacity (CI), and CI&II-linked OXPHOS and ET capacity were determined in a single SUIT protocol. Additionally, neutrophils, monocytes and lymphocytes (inflammatory response), creatine kinase (CK; muscular damage) and plasma markers of oxidative damage and repair were quantified at baseline and after the race.Absolute concentrations of all leukocyte subgroups and serum creatine kinase were changed significantly after the race. No significant changes were found in respiratory substrate control ratios CI/CI&II and CII/CI&II, neither when comparing PRE and POST, nor between POST and recovery. However, the ROUTINE coupling control ratio, R/E (ROUTINE respiration of intact cells, R, divided by uncoupler-stimulated electron transfer-pathway capacity, E) was increased significantly (+25,4% PRE vs. POST; +9,5% PRE vs. REC; ''p''<0.05), indicating the influence of massive physical strain and time of recovery on human platelet metabolism. We found a significant (''p''<0,05) relationship between BMI and CI/CI&II ratio, whereas age and training time per week were without significant effects on platelet metabolism.er week were without significant effects on platelet metabolism.)
Datzmann 2019 J Neurosurg + (Acute subdural hematoma (ASDH) is a leadin … Acute subdural hematoma (ASDH) is a leading entity in brain injury. Rodent models mostly lack standard intensive care, while large animal models frequently are only short term. Therefore, the authors developed a long-term, resuscitated porcine model of ASDH-induced brain injury and report their findings.Anesthetized, mechanically ventilated, and instrumented pigs with human-like coagulation underwent subdural injection of 20 mL of autologous blood and subsequent observation for 54 hours. Continuous bilateral multimodal brain monitoring (intracranial pressure [ICP], cerebral perfusion pressure [CPP], partial pressure of oxygen in brain tissue [PbtO2], and brain temperature) was combined with intermittent neurological assessment (veterinary modified Glasgow Coma Scale [MGCS]), microdialysis, and measurement of plasma protein S100β, GFAP, neuron-specific enolase [NSE], nitrite+nitrate, and isoprostanes. Fluid resuscitation and continuous intravenous norepinephrine were targeted to maintain CPP at pre-ASDH levels. Immediately postmortem, the brains were taken for macroscopic and histological evaluation, immunohistochemical analysis for nitrotyrosine formation, albumin extravasation, NADPH oxidase 2 (NOX2) and GFAP expression, and quantification of tissue mitochondrial respiration.Nine of 11 pigs survived the complete observation period. While ICP significantly increased after ASDH induction, CPP, PbtO2, and the MGCS score remained unaffected. Blood S100β levels significantly fell over time, whereas GFAP, NSE, nitrite+nitrate, and isoprostane concentrations were unaltered. Immunohistochemistry showed nitrotyrosine formation, albumin extravasation, NOX2 expression, fibrillary astrogliosis, and microglial activation.The authors describe a clinically relevant, long-term, resuscitated porcine model of ASDH-induced brain injury. Despite the morphological injury, maintaining CPP and PbtO2 prevented serious neurological dysfunction. This model is suitable for studying therapeutic interventions during hemorrhage-induced acute brain injury with standard brain-targeted intensive care.rrhage-induced acute brain injury with standard brain-targeted intensive care.)
Krumschnabel 2004 Aquat Toxicol + (Acute toxic effects of hexavalent chromium … Acute toxic effects of hexavalent chromium [Cr(VI)], a widely recognised carcinogenic, mutagenic and redox active metal, were investigated in isolated hepatocytes of goldfish (Carassius auratus). Exposure to 250 microM Cr(VI) induced a significant decrease of cell viability from 94% in controls to 88% and 84% after 30 min and 4 h of exposure, respectively. Cr-toxicity was associated with a concentration-dependent stimulation of the formation of reactive oxygen species (ROS). As one potential source of ROS formation we identified the lysosomal Fe(2+) pool, since the ferric ion chelator deferoxamin inhibited ROS formation by approximately 15%. Lysosomal membranes remained nevertheless intact during Cr-exposure, as determined from neutral red retention in this compartment. Another significant source of ROS appear to be the mitochondria, where a presumably uncoupled increase of respiration by 20-30% was triggered by the metal. Inhibition of mitochondrial respiration by cyanide caused an approximately 40% decrease of Cr-induced ROS-formation, whereas the uncoupling agent carbonyl cyanide m-chlorophenyl hydrazine was without effect. Cellular Ca(2+) homeostasis was not disturbed by Cr(VI) and thus played no role in this scenario. Overall, our data show that Cr(VI) is acutely toxic to goldfish hepatocytes, and its toxicity is associated with the induction of radical stress, presumably involving lysosomes and mitochondria as important sources of ROS formation.ria as important sources of ROS formation.)
Isola 2022 Abstract Bioblast + (Acutely exposure to low oxygen concentrati … Acutely exposure to low oxygen concentrations, impairs the capability to perform muscular workout. On the other hand, repeated and prolonged exposure to low PO2 may improve physical performance due to a progressive adaptation of the body. This is mainly due to enhanced hemoglobin and red blood cells content, and decreased sympathetic autonomic nervous system input. These changes were evaluated in a number of chronic hypoxia studies [1-2], whereas acute hypoxia outcomes are still unknown.This study investigates on acute hypoxia and normoxia impact on cardiac and brain mitochondrial bioenergetics and the possible occurrence of different gender responses.We used male and female Wistar rats that had been trained for 5 weeks, 1h/day, on a treadmill set at 35 cm/s. The day of the experiment they were allowed to run on the treadmill for 30 minutes in hypoxia (at the same oxygen concentration of an altitude of 4000 mt.) or in normoxia. After euthanasia, we removed the brain and the heart and isolated brain mitochondria, subsarcolemmal (SSM) and interfibrillar (IFM) heart mitochondria [3]. Mitochondrial bioenergetics was assessed by Clark-type electrode, testing for oxidative phosphorylation (OXPHOS): complex I (glutamate plus malate), complex II (rotenone plus succinate), complex III (rotenone plus durohydroquinone), complex IV (rotenone plus tetramethyl-p-phenylenediamine and ascorbate), Palmitoyl CoA as lipid substrate and adding at the end of the assay dinitrophenol (DNP) to test uncoupled respiration with these substrates.After acute hypoxia, brain male mitochondria showed an increase of uncoupled respiration at complex II and IV, whereas female mitochondria displayed no significant difference compared to controls.In heart male IFM mitochondria, following acute hypoxia, ADP/O decreased at complex I and II, compared with controls. Furthermore, in the same complexes data showed an increase of respiratory control ratio, but only complex I resulted statistically significant. These data suggest that hypoxia induced a mild uncoupling of IFM.Among female heart mitochondria, SSM only showed a decrease in state 3 of complex II after acute hypoxia.In conclusion, in both genders cardiac and brain mitochondrial bioenergetics change after athletic training in acute hypoxia.It seems that in female cardiac mitochondria hypoxia induced an impairment of complex II activity, while in male heart mitochondria the result need further investigation as it could be linked to a reported increased activity of ATPase under hypoxia [4] or a defective OXPHOS with a possible enhanced ROS production.In male brain mitochondria the increased of uncoupled respiration might be linked to a better efficiency of electron transfer system (ETS). Future studies will need to verify these results.# Horscroft JA, Kotwica AO, Laner V, West JA, Hennis PJ, Levett DZH, Howard DJ, Fernandez BO, Burgess SL, Ament Z, Gilbert-Kawai ET, Vercueil A, Landis BD, Mitchell K, Mythen MG, Branco C, Johnson RS, Feelisch M, Montgomery HE, Griffin JL, Grocott MPW, Gnaiger E, Martin DS, Murray AJ (2017) Metabolic basis to Sherpa altitude adaptation. https://doi.org/10.1073/pnas.1700527114# Levett DZ, Radford EJ, Menassa DA, Graber EF, Morash AJ, Hoppeler H, Clarke K, Martin DS, Ferguson-Smith AC, Montgomery HE, Grocott MP, Murray AJ; Caudwell Xtreme Everest Research Group (2012) Acclimatization of skeletal muscle mitochondria to high-altitude hypoxia during an ascent of Everest. https://doi.org/10.1096/fj.11-197772# Palmer JW, Tandler B, Hoppel CL (1977) Biochemical properties of subsarcolemmal and interfibrillar mitochondria isolated from rat cardiac muscle. https://www.jbc.org/article/S0021-9258(19)75283-1/pdf# Kioka H, Kato H, Fujikawa M, Tsukamoto O, Suzuki T, Imamura H, Nakano A, Higo S, Yamazaki S, Matsuzaki T, Takafuji K, Asanuma H, Asakura M, Minamino T, Shintani Y, Yoshida M, Noji H, Kitakaze M, Komuro I, Asano Y, Takashima S (2014) Evaluation of intramitochondrial ATP levels identifies G0/G1 switch gene 2 as a positive regulator of oxidative phosphorylation. https://doi.org/10.1073/pnas.1318547111https://doi.org/10.1073/pnas.1318547111 )
Fisher-Wellman 2019 Cell Rep + (Acyl CoA metabolites derived from the cata … Acyl CoA metabolites derived from the catabolism of carbon fuels can react with lysine residues of mitochondrial proteins, giving rise to a large family of post-translational modifications (PTMs). Mass spectrometry-based detection of thousands of acyl-PTMs scattered throughout the proteome has established a strong link between mitochondrial hyperacylation and cardiometabolic diseases; however, the functional consequences of these modifications remain uncertain. Here, we use a comprehensive respiratory diagnostics platform to evaluate three disparate models of mitochondrial hyperacylation in the mouse heart caused by genetic deletion of malonyl CoA decarboxylase (MCD), SIRT5 demalonylase and desuccinylase, or SIRT3 deacetylase. In each case, elevated acylation is accompanied by marginal respiratory phenotypes. Of the >60 mitochondrial energy fluxes evaluated, the only outcome consistently observed across models is a ∼15% decrease in ATP synthase activity. In sum, the findings suggest that the vast majority of mitochondrial acyl PTMs occur as stochastic events that minimally affect mitochondrial bioenergetics.Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.ished by Elsevier Inc. All rights reserved.)
Rajkumar 2018 Metabolism + (Acyl-CoA Synthetase Long Chain 5 (ACSL5) g … Acyl-CoA Synthetase Long Chain 5 (ACSL5) gene's rs2419621 T/C polymorphism was associated with ''ACSL5'' mRNA expression and response to lifestyle interventions. However, the mechanistic understanding of the increased response in T allele carriers is lacking. Study objectives were to investigate the effect of rs2419621 genotype and ACSL5 human protein isoforms on fatty acid oxidation and respiration.Human ACSL5 overexpression in C2C12 mouse myoblasts was conducted to measure 14C palmitic acid oxidation and protein isoform localization ''in vitro''. 14C palmitic acid oxidation studies and Western blot analysis of ACSL5 proteins were carried out in ''rectus abdominis'' primary myotubes from 5 rs2419621 T allele carriers and 4 non-carriers. In addition, mitochondrial high-resolution respirometry was conducted on ''vastus lateralis'' muscle biopsies from 4 rs2419621 T allele carriers and 4 non-carriers. Multiple linear regression analysis was conducted to test the association between rs2419621 genotype and respiratory quotient related pre- and post-lifestyle intervention measurements in postmenopausal women with overweight or obesity.In comparison to rs2419621 non-carriers, T allele carriers displayed higher levels of i) 683aa ACSL5 isoform, localized mainly in the mitochondria, playing a greater role in fatty acid oxidation in comparison to the 739aa protein isoform ii) ''in vitro'' CO2 production in ''rectus abdominis'' primary myotubes iii) ''in vivo'' fatty acid oxidation and lower carbohydrate oxidation post-intervention iv) ''ex vivo'' complex I and II tissue respiration in ''vastus lateralis'' muscle.These results support the conclusion that rs2419621 T allele carriers, are more responsive to lifestyle interventions partly due to an increase in the short ACSL5 protein isoform, increasing cellular, tissue and whole-body fatty acid utilization. With the increasing effort to develop personalized medicine to combat obesity, our findings provide additional insight into genotypes that can significantly affect whole body metabolism and response to lifestyle interventions.Copyright © 2018 Elsevier Inc. All rights reserved. lifestyle interventions. Copyright © 2018 Elsevier Inc. All rights reserved.)
Dambrova 2022 Abstract Bioblast + (Acylcarnitines are esters of L-carnitine t … Acylcarnitines are esters of L-carnitine that emerge from the energy metabolism pathways of fatty acids in mitochondria and peroxisomes [1]. Depending on the length of the acyl chain, acylcarnitines can be grouped as short-, medium-, long- and very long-chain acylcarnitines. Metabolomic profiling assays that investigate disease and nutrition states often include measurements of different acylcarnitines. This has resulted in increased interest regarding the consequences of elevated/decreased levels of plasma acylcarnitine concentrations and the mechanisms associated with these changes.Altered acylcarnitine metabolome is characteristic for certain inborn errors of fatty acid metabolism, as well as cardiovascular, metabolic and neurological diseases, and some forms of cancer. Acylcarnitines are considered as biomarkers for such diseases and pathological conditions as insulin resistance, heart failure and fatty acid oxidation metabolism-related inherited diseases. Long-chain acylcarnitines accumulate under conditions of insufficient mitochondrial functionality and can reach tissue levels that can affect enzyme and ion channel activities and impact energy metabolism pathways and cellular homeostasis. These detrimental processes directly impact mitochondrial physiology and can exaggerate arrhythmia, insulin insufficiency, neurodegenerative and neuropsychiatric conditions.Dietary and pharmacological means can be used to regulate synthesis and transport pathways of acylcarnitines and thus counteract the detrimental effects of their accumulation or reverse deficits. The most abundant acylcarnitines, acetylcarnitine and propionylcarnitine, are used as food supplements to tackle neurological and cardiovascular conditions.Better understanding of biochemical and molecular mechanisms behind increased/decreased acylcarnitine levels and their physiological and pathological roles forms basis for therapeutic target selection and preclinical drug discovery in future and also explains off-target effects of some clinically used drugs.# Dambrova M et al (2022) Acylcarnitines: nomenclature, biomarkers, therapeutic potential, drug targets and clinical trials. Pharmacol Rev 74:1-50 (in press).ials. Pharmacol Rev 74:1-50 (in press). )
Dambrova 2022 Pharmacol Rev + (Acylcarnitines are fatty acid metabolites … Acylcarnitines are fatty acid metabolites that play important roles in many cellular energy metabolism pathways. They have historically been used as important diagnostic markers for inborn errors of fatty acid oxidation and are being intensively studied as markers of energy metabolism, deficits in mitochondrial and peroxisomal β -oxidation activity, insulin resistance, and physical activity. Acylcarnitines are increasingly being identified as important indicators in metabolic studies of many diseases, including metabolic disorders, cardiovascular diseases, diabetes, depression, neurologic disorders, and certain cancers. The US Food and Drug Administration-approved drug L-carnitine, along with short-chain acylcarnitines (acetylcarnitine and propionylcarnitine), is now widely used as a dietary supplement. In light of their growing importance, we have undertaken an extensive review of acylcarnitines and provided a detailed description of their identity, nomenclature, classification, biochemistry, pathophysiology, supplementary use, potential drug targets, and clinical trials. We also summarize these updates in the Human Metabolome Database, which now includes information on the structures, chemical formulae, chemical/spectral properties, descriptions, and pathways for 1240 acylcarnitines. This work lays a solid foundation for identifying, characterizing, and understanding acylcarnitines in human biosamples. We also discuss the emerging opportunities for using acylcarnitines as biomarkers and as dietary interventions or supplements for many wide-ranging indications. The opportunity to identify new drug targets involved in controlling acylcarnitine levels is also discussed. SIGNIFICANCE STATEMENT: This review provides a comprehensive overview of acylcarnitines, including their nomenclature, structure and biochemistry, and use as disease biomarkers and pharmaceutical agents. We present updated information contained in the Human Metabolome Database website as well as substantial mapping of the known biochemical pathways associated with acylcarnitines, thereby providing a strong foundation for further clarification of their physiological roles.larification of their physiological roles.)
Ojuka 2015 Abstract MiPschool Cape Town 2015 + (Acylcarnitines when converted to acyl –CoA … Acylcarnitines when converted to acyl –CoA in the mitochondrial matrixare a major source of ATP after oxidation. Their oxidation process,termed β-oxidation, runs through four sequential enzymes namely:acyl-CoA dehydrogenase, 2-enoyl-CoA hydratase, L-3-hydroxyacyl-CoA dehydrogenase, and 3-ketoacyl-CoA thiolase [1]. Acyl-CoAdehydrogenases transfer single electrons to electron transferringflavoprotein (ETF) [2] which donates electrons directly to the ubiquinone(Q) pool in the mitochondrial inner membrane. Hydroxyacyl-CoAdehydrogenase transfers electrons to NAD+ and the reduced NADHis oxidized by complex I. The end product of β-oxidation, acetyl-CoA,condenses with oxaloacetate to form citrate which is oxidized by theKrebs cycle. Oxidation of fatty acylcarnitines therefore contributes toOXPHOS and ATP production by donating electrons at various points ofthe electron transfer-pathway.To assess oxidation of acylcarnitines under various experimentalconditions, scientist often measure oxygen consumption in isolatedmitochondria, permeabilized cells, or tissues in an oxygraph usinga variety of substrate combinations including palmatoylcarnitine incombination with carnitine or malate. Use of palmatoylcarnitine aloneyields low oxygen flux rates and is not responsive to ADP, oligomycinor uncouplers. These observations are attributed to a low CoA/palmatoylCoA ratio which inactivates 3-ketoacyl-CoA thiolase and slowsdown or stops β-oxidation. Use of palmatoylcarnitine in combination withcarnitine or malate increase State 2 respiration (oxygen consumptionwith substrate without addition of ADP) and are responsive to ADP,oligomycin and uncouples -- but to different degrees. The increase inoxygen flux rates after ADP or uncoupler addition is explained by theincreased CoA/palmatoylCoA ratio which favours β-oxidation. Thedifferences in response to ADP and uncoupler is probably due the factthat oxidation of palmitoylcarnitine in the presence of carnitine transferselectrons to the ETS without involving the Krebs cycle whereas oxidationof palmitoylcarnitine and malate does [3].of palmitoylcarnitine and malate does [3].)
Kang 2017 Mol Cell + (Acylglycerol kinase (AGK) is a mitochondri … Acylglycerol kinase (AGK) is a mitochondrial lipid kinase that catalyzes the phosphorylation of monoacylglycerol and diacylglycerol to lysophosphatidic acid and phosphatidic acid, respectively. Mutations in AGK cause Sengers syndrome, which is characterized by congenital cataracts, hypertrophic cardiomyopathy, skeletal myopathy, exercise intolerance, and lactic acidosis. Here we identified AGK as a subunit of the mitochondrial TIM22 protein import complex. We show that AGK functions in a kinase-independent manner to maintain the integrity of the TIM22 complex, where it facilitates the import and assembly of mitochondrial carrier proteins. Mitochondria isolated from Sengers syndrome patient cells and tissues show a destabilized TIM22 complex and defects in the biogenesis of carrier substrates. Consistent with this phenotype, we observe perturbations in the tricarboxylic acid (TCA) cycle in cells lacking AGK. Our identification of AGK as a bona fide subunit of TIM22 provides an exciting and unexpected link between mitochondrial protein import and Sengers syndrome.drial protein import and Sengers syndrome.)
Gak 2015 Biochim Biophys Acta + (Adaptability to stress is a fundamental pr … Adaptability to stress is a fundamental prerequisite for survival. Mitochondria are a key component of the stress response in all cells. For steroid-hormones-producing cells, including also Leydig cells of testes, the mitochondria are a key control point for the steroid biosynthesis and regulation. However, the mitochondrial biogenesis in steroidogenic cells has never been explored. Here we show that increased mitochondrial biogenesis is the adaptive response of testosterone-producing Leydig cells from stressed rats. All markers of mitochondrial biogenesis together with transcription factors and related kinases are up-regulated in Leydig cells from rats exposed to repeated psychophysical stress. This is followed with increased mitochondrial mass. The expression of PGC1, master regulator of mitochondrial biogenesis and integrator of environmental signals, is stimulated by cAMP-PRKA, cGMP, and β-adrenergic receptors. Accordingly, stress-triggered mitochondrial biogenesis represents an adaptive mechanism and does not only correlate with but also is an essential for testosterone production, being both events depend on the same regulators. Here we propose that all events induced by acute stress, the most common stress in human society, provoke adaptive response of testosterone-producing Leydig cells and activate PGC1, a protein required to make new mitochondria but also protector against the oxidative damage. Given the importance of mitochondria for steroid hormones production and stress response, as well as the role of steroid hormones in stress response and metabolic syndrome, we anticipate our result to be a starting point for more investigations since stress is a constant factor in life and has become one of the most significant health problems in modern societies.Copyright © 2015 Elsevier B.V. All rights reserved. © 2015 Elsevier B.V. All rights reserved.)
Mantilla 2017 PLOS Pathog + (Adaptation to different nutritional enviro … Adaptation to different nutritional environments is essential for life cycle completion by all ''Trypanosoma brucei'' sub-species. In the tsetse fly vector, L-proline is among the most abundant amino acids and is mainly used by the fly for lactation and to fuel flight muscle. The procyclic (insect) stage of ''T. b. brucei'' uses L-proline as its main carbon source, relying on an efficient catabolic pathway to convert it to glutamate, and then to succinate, acetate and alanine as the main secreted end products. Here we investigated the essentiality of an undisrupted proline catabolic pathway in ''T. b. brucei'' by studying mitochondrial Δ1-pyrroline-5-carboxylate dehydrogenase (TbP5CDH), which catalyzes the irreversible conversion of gamma-glutamate semialdehyde (γGS) into L-glutamate and NADH. In addition, we provided evidence for the absence of a functional proline biosynthetic pathway. TbP5CDH expression is developmentally regulated in the insect stages of the parasite, but absent in bloodstream forms grown ''in vitro''. RNAi down-regulation of TbP5CDH severely affected the growth of procyclic trypanosomes ''in vitro'' in the absence of glucose, and altered the metabolic flux when proline was the sole carbon source. Furthermore, TbP5CDH knocked-down cells exhibited alterations in the mitochondrial inner membrane potential (ΔΨm), respiratory control ratio and ATP production. Also, changes in the proline-glutamate oxidative capacity slightly affected the surface expression of the major surface glycoprotein EP-procyclin. In the tsetse, TbP5CDH knocked-down cells were impaired and thus unable to colonize the fly's midgut, probably due to the lack of glucose between bloodmeals. Altogether, our data show that the regulated expression of the proline metabolism pathway in ''T. b. brucei'' allows this parasite to adapt to the nutritional environment of the tsetse midgut.ritional environment of the tsetse midgut.)
Ter Veld 2005 FEBS J + (Adaptations of the kinetic properties of m … Adaptations of the kinetic properties of mitochondria in striated muscle lacking cytosolic (M) and/or mitochondrial (mt) creatine kinase (CK) isoforms in comparison to wild-type (WT) were investigated ''in vitro''. Intact mitochondria were isolated from heart and gastrocnemius muscle of WT and single- and double CK-knock-out mice strains (cytosolic (M-CK–/–), mitochondrial (mt-CK–/–) and double knock-out (mtM-CK–/–), respectively). Maximal ADP-stimulated oxygen consumption flux (State3 Vmax; nmol O2·mg mitochondrial protein–1·min–1) and ADP affinity (inline image; µm) were determined by respirometry. State 3 Vmax and inline image of M-CK–/– and mtIM-CK–/– gastrocnemius mitochondria were twofold higher than those of WT, but were unchanged for mt-CK–/–. For mutant cardiac mitochondria, only the inline image of mitochondria isolated from the mtM-CK–/– phenotype was different (i.e. twofold higher) than that of WT. The implications of these adaptations for striated muscle function were explored by constructing force-flow relations of skeletal muscle respiration. It was found that the identified shift in affinity towards higher ADP concentrations in mtM-CK–/– muscle genotypes may contribute to linear mitochondrial control of the reduced cytosolic ATP free energy potentials in these phenotypes.lt;sup>–/– muscle genotypes may contribute to linear mitochondrial control of the reduced cytosolic ATP free energy potentials in these phenotypes.)
Dogan 2014 Cell Metab + (Adaptive stress responses activated upon m … Adaptive stress responses activated upon mitochondrial dysfunction are assumed to arise in order to counteract respiratory chain deficiency. Here, we demonstrate that loss of DARS2 (mitochondrial aspartyl-tRNA synthetase) leads to the activation of various stress responses in a tissue-specific manner independently of respiratory chain deficiency. DARS2 depletion in heart and skeletal muscle leads to the severe deregulation of mitochondrial protein synthesis followed by a strong respiratory chain deficit in both tissues, yet the activation of adaptive responses is observed predominantly in cardiomyocytes. We show that the impairment of mitochondrial proteostasis in the heart activates the expression of mitokine FGF21, which acts as a signal for cell-autonomous and systemic metabolic changes. Conversely, skeletal muscle has an intrinsic mechanism relying on the slow turnover of mitochondrial transcripts and higher proteostatic buffering capacity. Our results show that mitochondrial dysfunction is sensed independently of respiratory chain deficiency, questioning the current view on the role of stress responses in mitochondrial diseases.Copyright © 2014 Elsevier Inc. All rights reserved. 2014 Elsevier Inc. All rights reserved.)
Puigserver 1998 Cell + (Adaptive thermogenesis is an important com … Adaptive thermogenesis is an important component of energy homeostasis and a metabolic defense against obesity. We have cloned a novel transcriptional coactivator of nuclear receptors, termed PGC-1, from a brown fat cDNA library. PGC-1 mRNA expression is dramatically elevated upon cold exposure of mice in both brown fat and skeletal muscle, key thermogenic tissues. PGC-1 greatly increases the transcriptional activity of PPARgamma and the thyroid hormone receptor on the uncoupling protein (UCP-1) promoter. Ectopic expression of PGC-1 in white adipose cells activates expression of UCP-1 and key mitochondrial enzymes of the respiratory chain, and increases the cellular content of mitochondrial DNA. These results indicate that PGC-1 plays a key role in linking nuclear receptors to the transcriptional program of adaptive thermogenesis.ptional program of adaptive thermogenesis.)
Ransy 2020 Int J Mol Sci + (Addition of hydrogen peroxide (H … Addition of hydrogen peroxide (H2O2) is a method commonly used to trigger cellular oxidative stress. However, the doses used (often hundreds of micromolar) are disproportionally high with regard to physiological oxygen concentration (low micromolar). In this study using polarographic measurement of oxygen concentration in cellular suspensions we show that H2O2 addition results in O2 release as expected from catalase reaction. This reaction is fast enough to, within seconds, decrease drastically H2O2 concentration and to annihilate it within a few minutes. Firstly, this is likely to explain why recording of oxidative damage requires the high concentrations found in the literature. Secondly, it illustrates the potency of intracellular antioxidant (H2O2) defense. Thirdly, it complicates the interpretation of experiments as subsequent observations might result from high/transient H2O2 exposure and/or from the diverse possible consequences of the O2 release. as subsequent observations might result from high/transient H2O2 exposure and/or from the diverse possible consequences of the O2 release.)
Ratajczak 2019 Anal Bioanal Chem + (Adenosine triphosphate (ATP) is the main e … Adenosine triphosphate (ATP) is the main energy source in cells and an important biomolecule participating in cellular reactions in living organisms. Since the ATP level changes dynamically reflecting the development of a debilitating disease or carcinogenesis, we have focused in this work on monitoring of the oligomycin (OMC)-modulated ATP synthase inhibition using a fluorescent-switching DNA aptamer designed for the detection of ATP (Apt(ATP)), as the model for studies of dynamic ATP level variation. The behavior of the ATP aptamer has been characterized using fluorescence spectroscopy. The Intramolecular fluorescence resonance energy transfer (iFRET) operates in the proposed aptamer from the FAM dye moiety to guanines of the aptamer G-quadruplex when the target ATP is present and binds to the aptamer changing its conformation. The iFRET process enables the detection of ATP down to the limit of detection, LOD = 17 μM, without resorting to any extra chemi-amplification schemes. The selectivity coefficients for relevant interferent triphosphates (UTP, GTP, and CTP) are low for the same concentration as that of ATP. We have demonstrated an efficient transfection of intact cells and OMC-treated SW480 colon cancer cells with Apt(ATP), using microscopic imaging, iFRET measurements, and cell viability testing with MTT method. The applicability of the switching DNA aptamer for the analysis of real samples, obtained by lysis of SW480 cells, was also tested. The proposed Apt(ATP) may be considered as a viable candidate for utilization in measurements of dynamic ATP level modulation in cells in different stages of cancer development and testing of new drugs in pharmacological studies.g of new drugs in pharmacological studies.)
Baldini 2021 Life Sci + (Adipocyte hypertrophy is the main cause of … Adipocyte hypertrophy is the main cause of obesity. A deeper understanding of the molecular mechanisms regulating adipocyte dysfunction may help to plan strategies to treat/prevent obesity and its metabolic complications. Here, we investigated ''in vitro'' the molecular alterations associated with early adipocyte hypertrophy, focusing on mitochondrial dysfunction.As model of adipocyte hypertrophy, we employed 3T3-L1 preadipocytes firstly differentiated into mature adipocytes, then cultured with long-chain fatty acids. As a function of differentiation and hypertrophy, we assessed triglyceride content, lipid droplet size, radical homeostasis by spectrophotometry and microscopy, as well as the expression of PPARγ, adiponectin and metallothioneins. Mitochondrial status was investigated by electron microscopy, Oxygraph-2k (O2K) high-resolution respirometry, fluorimetry and western blot.Compared to mature adipocytes, hypertrophic adipocytes showed increased triglyceride accumulation and lipid peroxidation, larger or unique lipid droplet, up-regulated expression of PPARγ, adiponectin and metallothioneins. At mitochondrial level, early-hypertrophic adipocytes exhibited: (i) impaired mitochondrial oxygen consumption with parallel reduction in the mitochondrial complexes; (ii) no changes in citrate synthase and HSP60 expression, and in the inner mitochondrial membrane polarization; (iii) no stimulation of mitochondrial fatty acid oxidation. Our findings indicate that the content, integrity, and catabolic activity of mitochondria were rather unchanged in early hypertrophic adipocytes, while oxygen consumption and oxidant production were altered.In the model of early adipocyte hypertrophy exacerbated oxidative stress and impaired mitochondrial respiration were observed, likely depending on reduction in the mitochondrial complexes, without changes in mitochondrial mass and integrity.anges in mitochondrial mass and integrity.)
Bikman 2022 Eur J Clin Nutr + (Adipocyte mitochondrial respiration may in … Adipocyte mitochondrial respiration may influence metabolic fuel partitioning into oxidation versus storage, with implications for whole-body energy expenditure. Although insulin has been shown to influence mitochondrial respiration, the effects of dietary macronutrient composition have not been well characterized. The aim of this exploratory study was to test the hypothesis that a high-carbohydrate diet lowers the oxygen flux of adipocyte mitochondria ''ex vivo''. Among participants in a randomized-controlled weight-loss maintenance feeding trial, those consuming a high-carbohydrate diet (60% carbohydrate as a proportion of total energy, n = 10) had lower rates of maximal adipose tissue mitochondrial respiration than those consuming a moderate-carbohydrate diet (40%, n = 8, p = 0.039) or a low-carbohydrate diet (20%, n = 9, p = 0.005) after 10 to 15 weeks. This preliminary finding may provide a mechanism for postulated calorie-independent effects of dietary composition on energy expenditure and fat deposition, potentially through the actions of insulin on fuel partitioning.e actions of insulin on fuel partitioning.)
Llobet 2015 Dis Model Mech + (Adipogenesis is accompanied by differentia … Adipogenesis is accompanied by differentiation of adipose tissue-derived stem cells to adipocytes. As a part of this differentiation, biogenesis of the oxidative phosphorylation system occurs. Many chemical compounds used in medicine, agriculture, or other human activities, affect the oxidative phosphorylation function. Therefore, these xenobiotics could alter adipogenesis. We have analyzed the effects on adipocyte differentiation of some xenobiotics that act on the oxidative phosphorylation system. The tested concentrations have been previously reported in human blood. Our results show that pharmaceutical drugs that decrease mitochondrial DNA replication, such as nucleoside reverse transcriptase inhibitors, or inhibitors of mitochondrial protein synthesis, like ribosomal antibiotics, diminish adipocyte differentiation and leptin secretion. On the other hand, the environmental chemical pollutant tributyltin chloride, inhibiting the ATP synthase of the oxidative phosphorylation system, can promote adipocyte differentiation and leptin secretion, leading to obesity and metabolic syndrome as the obesogen hypothesis postulates.ome as the obesogen hypothesis postulates.)
Shi 2023 Redox Biol + (Adipose plasticity is critical for metabol … Adipose plasticity is critical for metabolic homeostasis. Adipocyte transdifferentiation plays an important role in adipose plasticity, but the molecular mechanism of transdifferentiation remains incompletely understood. Here we show that the transcription factor FoxO1 regulates adipose transdifferentiation by mediating Tgfβ1 signaling pathway. Tgfβ1 treatment induced whitening phenotype in beige adipocytes, reducing UCP1 and mitochondrial capacity and enlarging lipid droplets. Deletion of adipose FoxO1 (adO1KO) dampened Tgfβ1 signaling by downregulating Tgfbr2 and Smad3 and induced browning of adipose tissue in mice, increasing UCP1 and mitochondrial content and activating metabolic pathways. Silencing FoxO1 also abolished the whitening effect of Tgfβ1 on beige adipocytes. The adO1KO mice exhibited a significantly higher energy expenditure, lower fat mass, and smaller adipocytes than the control mice. The browning phenotype in adO1KO mice was associated with an increased iron content in adipose tissue, concurrent with upregulation of proteins that facilitate iron uptake (DMT1 and TfR1) and iron import into mitochondria (Mfrn1). Analysis of hepatic and serum iron along with hepatic iron-regulatory proteins (ferritin and ferroportin) in the adO1KO mice revealed an adipose tissue-liver crosstalk that meets the increased iron requirement for adipose browning. The FoxO1-Tgfβ1 signaling cascade also underlay adipose browning induced by β3-AR agonist CL316243. Our study provides the first evidence of a FoxO1-Tgfβ1 axis in the regulation of adipose browning-whitening transdifferentiation and iron influx, which sheds light on the compromised adipose plasticity in conditions of dysregulated FoxO1 and Tgfβ1 signaling.of dysregulated FoxO1 and Tgfβ1 signaling.)
Lefranc 2019 Hypertension + (Adipose tissue (AT) senescence and mitocho … Adipose tissue (AT) senescence and mitochondrial dysfunction are associated with obesity. Studies in obese patients and animals demonstrate that the MR (mineralocorticoid receptor) contributes to obesity-associated cardiovascular complications through its specific role in AT. However, underlying mechanisms remain unclear. This study aims to elucidate whether MR regulates mitochondrial function in obesity, resulting in AT premature aging and vascular dysfunction. Obese (db/db) and lean (db/+) mice were treated with an MR antagonist or a specific mitochondria-targeted antioxidant. Mitochondrial and vascular functions were determined by respirometry and myography, respectively. Molecular mechanisms were probed by Western immunoblotting and real-time polymerase chain reaction in visceral AT and arteries and focused on senescence markers and redox-sensitive pathways. db/db mice displayed AT senescence with activation of the p53-p21 pathway and decreased SIRT (sirtuin) levels, as well as mitochondrial dysfunction. Furthermore, the beneficial anticontractile effects of perivascular AT were lost in db/db via ROCK (Rho kinase) activation. MR blockade prevented these effects. Thus, MR activation in obesity induces mitochondrial dysfunction and AT senescence and dysfunction, which consequently increases vascular contractility. In conclusion, our study identifies novel mechanistic insights involving MR, adipose mitochondria, and vascular function that may be of importance to develop new therapeutic strategies to limit obesity-associated cardiovascular complications.y-associated cardiovascular complications.)
Dela MiP2010 + (Adipose tissue exerts important endocrine … Adipose tissue exerts important endocrine and metabolic functions in health and disease. Yet the bioenergetics of this tissue is not characterized in humans and possible regional differences are not elucidated. Using high-resolution respirometry, mitochondrial respiration was quantified in human abdominal subcutaneous and intra-abdominal, visceral (omentum majus) adipose tissue from biopsies obtained in twenty obese patients undergoing bariatric surgery. [[mtDNA]] and gDNA were determined by PCR technique for estimation of mitochondrial density. Adipose tissue samples were permeabilized and respirometric measurements were performed in duplicate at 37 °C. Substrates [glutamate(G) + malate(M) + octanoyl carnitine(Oct) + succinate(S)] were added sequentially to provide electrons to Complexes CI + CII. ADP (D) for [[State 3]] respiration was added after GM. Non-coupled respiration was measured after addition of FCCP. Visceral fat contained more mitochondria per mg tissue than subcutaneous fat, but the cells were smaller. Robust, stable oxygen fluxes were found in both tissues, and coupled State 3 (GMOctSD) and non-coupled respiration were significantly (''P''<0.05) higher in visceral (0.95±0.05 and 1.15±0.06 pmol O2∙s-1∙mg-1, respectively) compared with subcutaneous (0.76±0.04 and 0.98±0.05 pmol O2∙s-1∙mg-1, respectively) adipose tissue. Expressed per mtDNA, visceral adipose tissue had significantly (''P''<0.05) lower mitochondrial respiration. Substrate control ratios were higher and uncoupling control ratio lower (''P''<0.05) in visceral compared with subcutaneous adipose tissue. Visceral fat is bioenergetically more active and more sensitive to mitochondrial substrate supply than subcutaneous fat. [[OXPHOS]] has a higher relative activity in visceral compared with subcutaneous adipose tissue.s a higher relative activity in visceral compared with subcutaneous adipose tissue.)
Kraunsoee 2010 J Physiol + (Adipose tissue exerts important endocrine … Adipose tissue exerts important endocrine and metabolic functions in health and disease. Yet the bioenergetics of this tissue is not characterized in humans and possible regional differences are not elucidated. Using high-resolution respirometry, mitochondrial respiration was quantified in human abdominal subcutaneous and intra-abdominal visceral (omentum majus) adipose tissue from biopsies obtained in 20 obese patients undergoing bariatric surgery. Mitochondrial DNA (mtDNA) and genomic DNA (gDNA) were determined by the PCR technique for estimation of mitochondrial density. Adipose tissue samples were permeabilized and respirometric measurements were performed in duplicate at 37 °C. Substrates (glutamate (G) + malate (M) + octanoyl carnitine (Oct) + succinate (S)) were added sequentially to provide electrons to Complex I+II. ADP (D) for State 3 respiration was added after GM. Non-coupled respiration was measured after addition of FCCP. Visceral fat contained more mitochondria per milligram of tissue than subcutaneous fat, but the cells were smaller. Robust, stable oxygen fluxes were found in both tissues, and coupled State 3 (GMOctS(D)) and non-coupled respiration were significantly (''P'' < 0.05) higher in visceral (0.95 +/- 0.05 and 1.15 +/- 0.06 pmol O(2) s-1 mg-1, respectively) compared with subcutaneous (0.76 +/- 0.04 and 0.98 +/- 0.05 pmol O(2) s-1 mg-1, respectively) adipose tissue. Expressed per mtDNA, visceral adipose tissue had significantly (''P'' < 0.05) lower mitochondrial respiration. Substrate control ratios were higher and uncoupling control ratio lower (''P'' < 0.05) in visceral compared with subcutaneous adipose tissue. We conclude that visceral fat is bioenergetically more active and more sensitive to mitochondrial substrate supply than subcutaneous fat. Oxidative phosphorylation has a higher relative activity in visceral compared with subcutaneous adipose tissue.Oxidative phosphorylation has a higher relative activity in visceral compared with subcutaneous adipose tissue.)
Sahl 2021 Adipocyte + (Adipose tissue mitochondrial function is g … Adipose tissue mitochondrial function is gaining increasing interest since it is good marker of overall health. Methodological challenges and variability in assessing mitochondrial respiration in fresh adipose tissue with high resolution respirometry are unknown and should be explored. Mitochondrial respiratory capacity (MRC) in human adipose tissue decline in a gradual manner when analyses are postponed 3h and 24h, with a statistically significant decline 24h after obtaining the biopsy. This decline in MRC is associated with a reduced integrity of the outer mitochondrial membrane at both time points. This study suggest that the optimal amount of tissue to be used is 20mg and that different technicians handling the biopsy do not affect MRC.ans handling the biopsy do not affect MRC.)
Pino 2023 Abstract IOC162 + (Adipose tissue, which is the crucial energ … Adipose tissue, which is the crucial energy reservoir and endocrine organ for the maintenance of systemic glucose, lipid, and energy homeostasis, undergoes significant changes during aging. Ageing also impacts the circadian clock (CC) machinery of peripheral organs including white adipose tissue. Together, these alterations cause age-related disease in the elderly population. The aim of this study is to investigate the transcriptional expression of circadian clock genes, cell proliferation rates and mitochondrial capacity of adipose-derived stem cells (ASCs) isolated from abdominal subcutaneous white adipose tissue (scWAT) from old and young individuals.10 old (5 females) and 10 young individuals (5 females) participated in this study. To measure CC related genes, proliferating ASCs were synchronized with 30% fetal bovine serum (FBS) for two hours, then media was replaced with 2% FBS and RNA was collected every six hours for a duration of 48 hrs and targeted gene expression was measured by qRT-PCR. To measure cells proliferation, ASCs were plated in 96 well plate and cell proliferation was measured with CellTiter-Glow luminescent cell viability kit (Promega, USA) for a period of 72 hrs. Mitochondrial capacity, oxygen consumption rates, were measured in proliferating ASCs via high-resolution respirometry using the Oxygraph-2K (Oroboros instruments, Innsbruck, Austria).An increase in mRNA levels of CLOCK and PER2 and a loss of rhythmicity for CLOCK and CRY1 were observed in ASCs from older individuals compared to the young. mRNA levels and rhythmicity of BMAL, PER1, DBP, NR1D1 and NR1D2 were not altered by age. We are currently determining cell proliferation and mitochondrial capacity in ASCs. Overall, age does not seem to affect CC rhythmicity in ASCs isolated from scWAT from old and young individuals.from scWAT from old and young individuals.)
Irion 2020 Stem Cells Int + (Adipose-derived mesenchymal stromal cell ( … Adipose-derived mesenchymal stromal cell (AD-MSC) administration improves cardiac function after acute myocardial infarction (AMI). Although the mechanisms underlying this effect remain to be elucidated, the reversal of the mitochondrial dysfunction may be associated with AMI recovery. Here, we analyzed the alterations in the respiratory capacity of cardiomyocytes in the infarcted zone (IZ) and the border zone (BZ) and evaluated if mitochondrial function improved in cardiomyocytes after AD-MSC transplantation. Female rats were subjected to AMI by permanent left anterior descending coronary (LAD) ligation and were then treated with AD-MSCs or PBS in the border zone (BZ). Cardiac fibers were analyzed 24 hours (necrotic phase) and 8 days (fibrotic phase) after AMI for mitochondrial respiration, citrate synthase (CS) activity, F0F1-ATPase activity, and transmission electron microscopy (TEM). High-resolution respirometry of permeabilized cardiac fibers showed that AMI reduced numerous mitochondrial respiration parameters in cardiac tissue, including phosphorylating and nonphosphorylating conditions, respiration coupled to ATP synthesis, and maximal respiratory capacity. CS decreased in IZ and BZ at the necrotic phase, whereas it recovered in BZ and continued to drop in IZ over time when compared to Sham. Exogenous cytochrome c doubled respiration at the necrotic phase in IZ. F0F1-ATPase activity decreased in the BZ and, to more extent, in IZ in both phases. Transmission electron microscopy showed disorganized mitochondrial cristae structure, which was more accentuated in IZ but also important in BZ. All these alterations in mitochondrial respiration were still present in the group treated with AD-MSC. In conclusion, AMI led to mitochondrial dysfunction with oxidative phosphorylation disorders, and AD-MSC improved CS temporarily but was not able to avoid alterations in mitochondria function over time.d CS temporarily but was not able to avoid alterations in mitochondria function over time.)
Santos-Silva 2023 Transl Psychiatry + (Adolescent individuals exhibit great varia … Adolescent individuals exhibit great variability in cortical dynamics and behavioral outcomes. The developing adolescent brain is highly sensitive to social experiences and environmental insults, influencing how personality traits emerge. A distinct pattern of mitochondrial gene expression in the prefrontal cortex (PFC) during adolescence underscores the essential role of mitochondria in brain maturation and the development of mental illnesses. Mitochondrial features in certain brain regions account for behavioral differences in adulthood. However, it remains unclear whether distinct adolescent behavioral phenotypes and the behavioral consequences of early adolescent stress exposure in rats are accompanied by changes in PFC mitochondria-related genes and mitochondria respiratory chain capacity. We performed a behavioral characterization during late adolescence (postnatal day, PND 47-50), including naïve animals and a group exposed to stress from PND 31-40 (10 days of footshock and 3 restraint sessions) by z-normalized data from three behavioral domains: anxiety (light-dark box tests), sociability (social interaction test) and cognition (novel-object recognition test). Employing principal component analysis, we identified three clusters: naïve with higher-behavioral z-score (HBZ), naïve with lower-behavioral z-score (LBZ), and stressed animals. Genome-wide transcriptional profiling unveiled differences in the expression of mitochondria-related genes in both naïve LBZ and stressed animals compared to naïve HBZ. Genes encoding subunits of oxidative phosphorylation complexes were significantly down-regulated in both naïve LBZ and stressed animals and positively correlated with behavioral z-score of phenotypes. Our network topology analysis of mitochondria-associated genes found Ndufa10 and Cox6a1 genes as central identifiers for naïve LBZ and stressed animals, respectively. Through high-resolution respirometry analysis, we found that both naïve LBZ and stressed animals exhibited a reduced prefrontal phosphorylation capacity and redox dysregulation. Our findings identify an association between mitochondrial features and distinct adolescent behavioral phenotypes while also underscoring the detrimental functional consequences of adolescent stress on the PFC.sequences of adolescent stress on the PFC.)
Mahdaviani 2014 Abstract MiP2014 + (Adrenergic stimulation of brown adipocytes … Adrenergic stimulation of brown adipocytes (BA) induces mitochondrial uncoupling, thereby increasing energy expenditure by shifting nutrient oxidation towards thermogenesis [1]. The brown adipocyte is a unique system to study the relationship between mitochondrial architecture and bioenergetic function. Here we describe that mitochondrial dynamics is a physiological regulator of adrenergically‐induced changes in energy expenditure. Brown pre-adipocyes were harvested from 4-week-old wild-type male C57BL6/J mice and differentiated in culture. Oxygen consumption was measured using Seahorse XF24. Mitochondrial membrane potential was measured using TMRE and Zeiss LSM 710 confocal microscope. Measurements were taken before and after activation with NE (1 uM) and FFA (palmitate or oleate, 0.4 mM).The sympathetic neurotransmitter norepinephrine (NE) induced complete and rapid mitochondrial fragmentation in BA, characterized by Drp1 phosphorylation and Opa1 cleavage. Mechanistically, NE‐mediated Drp1 phosphorylation was dependent on protein kinase‐A (PKA) activity [2], whereas Opa1 cleavage required mitochondrial depolarization, mediated by FFAs released as a result of lipolysis. This change in mitochondrial architecture was observed both in primary cultures and brown adipose tissue from cold‐exposed mice. Mitochondrial uncoupling, induced by NE in brown adipocytes, was reduced by inhibition of mitochondrial fission through transient Drp1 DN overexpression. Furthermore, forced mitochondrial fragmentation in BA through Mfn2 knock down increased the capacity of exogenous FFAs to increase energy expenditure.These results suggest that, in addition to its ability to stimulate lipolysis, NE induces energy expenditure in BA by promoting mitochondrial fragmentation. Taken together these data reveal that adrenergically‐induced changes of mitochondrial dynamics are required for BA thermogenic activation and for the control of energy expenditure.and for the control of energy expenditure.)
Anmann 2014 Biochim Biophys Acta + (Adult cardiomyocytes have highly organized … Adult cardiomyocytes have highly organized intracellular structure and energy metabolism whose formation during postnatal development is still largely unclear. Our previous results together with the data from the literature suggest that cytoskeletal proteins, particularly βII-tubulin, are involved in the formation of complexes between mitochondria and energy consumption sites. The aim of this study was to examine the arrangement of intracellular architecture parallel to the alterations in regulation of mitochondrial respiration in rat cardiomyocytes during postnatal development, from 1day to 6months. Respirometric measurements were performed to study the developmental alterations of mitochondrial function. Changes in the mitochondrial arrangement and cytoarchitecture of βII- and αIV-tubulin were examined by confocal microscopy. Our results show that functional maturation of oxidative phosphorylation in mitochondria is completed much earlier than efficient feedback regulation is established between mitochondria and ATPases via creatine kinase system. These changes are accompanied by significant remodeling of regular intermyofibrillar mitochondrial arrays aligned along the bundles of βII-tubulin. Additionally, we demonstrate that formation of regular arrangement of mitochondria is not sufficient per se to provide adult-like efficiency in metabolic feed-back regulation, but organized tubulin networks and reduction in mitochondrial outer membrane permeability for ADP are necessary as well. In conclusion, cardiomyocytes in rat heart become mature on the level of intracellular architecture and energy metabolism at the age of 3months.d energy metabolism at the age of 3months.)
Soares 2015 PLoS One + (Adult females of ''Aedes aegypti'' are fac … Adult females of ''Aedes aegypti'' are facultative blood sucking insects and vectors of Dengue and yellow fever viruses. Insect dispersal plays a central role in disease transmission and the extremely high energy demand posed by flight is accomplished by a very efficient oxidative phosphorylation process, which take place within flight muscle mitochondria. These organelles play a central role in energy metabolism, interconnecting nutrient oxidation to ATP synthesis, but also represent an important site of cellular superoxide production. Given the importance of mitochondria to cell physiology, and the potential contributions of this organelle for ''A. aegypti'' biology and vectorial capacity, here, we conducted a systematic assessment of mitochondrial physiology in flight muscle of young adult ''A. aegypti'' fed exclusively with sugar. This was carried out by determining the activities of mitochondrial enzymes, the substrate preferences to sustain respiration, the mitochondrial bioenergetic efficiency and capacity, in both mitochondria-enriched preparations and mechanically permeabilized flight muscle in both sexes. We also determined the substrates preferences to promote mitochondrial superoxide generation and the main sites where it is produced within this organelle. We observed that respiration in ''A. aegypti'' mitochondria was essentially driven by complex I and glycerol 3 phosphate dehydrogenase substrates, which promoted distinct mitochondrial bioenergetic capacities, but with preserved efficiencies. Respiration mediated by proline oxidation in female mitochondria was strikingly higher than in males. Mitochondrial superoxide production was essentially mediated through proline and glycerol 3 phosphate oxidation, which took place at sites other than complex I. Finally, differences in mitochondrial superoxide production among sexes were only observed in male oxidizing glycerol 3 phosphate, exhibiting higher rates than in female. Together, these data represent a significant step towards the understanding of fundamental mitochondrial processes in ''A. aegypti'', with potential implications for its physiology and vectorial capacity.for its physiology and vectorial capacity.)
Bennett 2021 Biomedicines + (Adult human brains consume a disproportion … Adult human brains consume a disproportionate amount of energy substrates (2-3 % of body weight; 20-25 % of total glucose and oxygen). Adenosine triphosphate (ATP) is a universal energy currency in brains and is produced by oxidative phosphorylation (OXPHOS) using ATP synthase, a nano-rotor powered by the proton gradient generated from proton-coupled electron transfer (PCET) in the multi-complex electron transport chain (ETC). ETC catalysis rates are reduced in brains from humans with neurodegenerative diseases (NDDs). Declines of ETC function in NDDs may result from combinations of nitrative stress (NS)-oxidative stress (OS) damage; mitochondrial and/or nuclear genomic mutations of ETC/OXPHOS genes; epigenetic modifications of ETC/OXPHOS genes; or defects in importation or assembly of ETC/OXPHOS proteins or complexes, respectively; or alterations in mitochondrial dynamics (fusion, fission, mitophagy). Substantial free energy is gained by direct O2-mediated oxidation of NADH. Traditional ETC mechanisms require separation between O2 and electrons flowing from NADH/FADH2 through the ETC. Quantum tunneling of electrons and much larger protons may facilitate this separation. Neuronal death may be viewed as a local increase in entropy requiring constant energy input to avoid. The ATP requirement of the brain may partially be used for avoidance of local entropy increase. Mitochondrial therapeutics seeks to correct deficiencies in ETC and OXPHOS.to correct deficiencies in ETC and OXPHOS.)
Teulier 2018 J Fish Biol + (Adult zebrafish ''Danio rerio'' were expos … Adult zebrafish ''Danio rerio'' were exposed to an electric shock of 3 V and 1A for 5 s delivered by field backpack electrofishing gear, to induce a taxis followed by a narcosis. The effect of such electric shock was investigated on both the individual performances (swimming capacities and costs of transport) and at cellular and mitochondrial levels (oxygen consumption and oxidative balance). The observed survival rate was very high (96·8%) independent of swimming speed (up to 10 body length s-1). The results showed no effect of the treatment on the metabolism and cost of transport of the fish. Nor did the electroshock trigger any changes on muscular oxidative balance and bioenergetics even if red muscle fibres were more oxidative than white muscle. Phosphorylating respiration rates rose between (mean 1 s.e.) 11·16 ± 1·36 pmol O2 s-1 mg-1 and 15·63 ± 1·60 pmol O2 s-1 mg-1 for red muscle fibres whereas phosphorylating respiration rates only reached 8·73 ± 1·27 pmol O2 s-1 mg-1 in white muscle. Such an absence of detectable physiological consequences after electro-induced narcosis both at organismal and cellular scales indicate that this capture method has no apparent negative post-shock performance under the conditions of this study.cosis both at organismal and cellular scales indicate that this capture method has no apparent negative post-shock performance under the conditions of this study.)
Benes 2011 Clin Sci (Lond) + (Advanced HF (heart failure) is associated … Advanced HF (heart failure) is associated with altered substrate metabolism. Whether modification of substrate use improves the course of HF remains unknown. The antihyperglycaemic drug MET (metformin) affects substrate metabolism, and its use might be associated with improved outcome in diabetic HF. The aim of the present study was to examine whether MET would improve cardiac function and survival also in non-diabetic HF. Volume-overload HF was induced in male Wistar rats by creating ACF (aortocaval fistula). Animals were randomized to placebo/MET (300 mg·kg(-1) of body weight·day(-1), 0.5% in food) groups and underwent assessment of metabolism, cardiovascular and mitochondrial functions (n=6-12/group) in advanced HF stage (week 21). A separate cohort served for survival analysis (n=10-90/group). The ACF group had marked cardiac hypertrophy, increased LVEDP (left ventricular end-diastolic pressure) and lung weight confirming decompensated HF, increased circulating NEFAs (non-esterified 'free' fatty acids), intra-abdominal fat depletion, lower glycogen synthesis in the skeletal muscle (diaphragm), lower myocardial triacylglycerol (triglyceride) content and attenuated myocardial (14)C-glucose and (14)C-palmitate oxidation, but preserved mitochondrial respiratory function, glucose tolerance and insulin sensitivity. MET therapy normalized serum NEFAs, decreased myocardial glucose oxidation, increased myocardial palmitate oxidation, but it had no effect on myocardial gene expression, AMPK (AMP-activated protein kinase) signalling, ATP level, mitochondrial respiration, cardiac morphology, function and long-term survival, despite reaching therapeutic serum levels (2.2±0.7 μg/ml). In conclusion, MET-induced enhancement of myocardial fatty acid oxidation had a neutral effect on cardiac function and survival. Recently reported cardioprotective effects of MET may not be universal to all forms of HF and may require AMPK activation or ATP depletion. No increase in mortality on MET supports its safe use in diabetic HF. MET supports its safe use in diabetic HF.)
National Academies of Sciences, Engineering, and Medicine 2018 Science data infrastructure + (Advances in science and technology have le … Advances in science and technology have led to the creation of large amounts of data—data that could be harnessed to improve productivity, cure disease, and address many other critical issues. Consensus in the scientific community is growing that the transition to truly data-driven and open science is best achieved by the establishment of a globally interoperable research infrastructure.A number of projects are looking to establish this infrastructure and exploit data to its fullest potential. Several projects in the United States, Europe, and China have made significant strides toward this effort. The goal of these projects is to make research data findable, accessible, interoperable, and reusable, or FAIR (see Box 1). The expected impact and benefits of FAIR data are substantial. To realize these benefits, there is a need to examine critical success factors for implementation, including training of a new generation of data experts to provide the necessary capacity.On November 1, 2017, the Board on Research Data and Information (BRDI) of the National Academies ofSciences, Engineering, and Medicine organized a symposium to explore these issues. Invited experts from China, Europe, and the United States were asked to:* Review proposed science data infrastructure projects around the globe;* Highlight, compare, and contrast the plans and capabilities of these projects; and* Discuss the critical success factors for implementation and the role of international cooperation for scientific data management.ooperation for scientific data management.)
Cedrone 2019 Thesis + (Adverse ''in utero'' and postnatal conditi … Adverse ''in utero'' and postnatal conditions can increase susceptibility to metabolic syndrome (MS). Altered muscle respiration contributes to MS, but the effects of restricted oxygen and nutrients ''in utero'' on skeletal muscle mitochondria remain unknown. In this study guinea pig sows underwent uterine artery ablations mid-gestation, producing fetuses with low birth weight (LBW). Soleus muscle was collected near term or at four months of age, from LBW and control fetuses and offspring, where the offspring were fed either a Western Diet (WD) or a control diet (CD). Soleus muscles from LBW fetuses exhibit lower maximal respiration rates than normal birth weight (NBW) sham-surgery controls. Additionally, LBW/CD, NBW/WD and LBW/WD adult guinea pigs displayed reduced respiration compared with NBW/CD. Cultured C2C12 cells were utilized to better understand independent effects of hypoxia and fatty acid saturation upon cellular respiration. Both chronic (5 days) hypoxia and palmitate (16:0) reduced respiration compared with normoxia.educed respiration compared with normoxia.)
Santana-Roman 2021 Insects + (Aedes aegypti and Aedes albopictus mosquit … Aedes aegypti and Aedes albopictus mosquitoes are responsible for dengue virus (DENV) transmission in tropical and subtropical areas worldwide, where an estimated 3 billion people live at risk of DENV exposure. DENV-infected individuals show symptoms ranging from sub-clinical or mild to hemorrhagic fever. Infected mosquitoes do not show detectable signs of disease, even though the virus maintains a lifelong persistent infection. The interactions between viruses and host mitochondria are crucial for virus replication and pathogenicity. DENV infection in vertebrate cells modulates mitochondrial function and dynamics to facilitate viral proliferation. Here, we describe that DENV also regulates mitochondrial function and morphology in infected C6/36 mosquito cells (derived from Aedes albopictus). Our results showed that DENV infection increased ROS (reactive oxygen species) production, modulated mitochondrial transmembrane potential and induced changes in mitochondrial respiration. Furthermore, we offer the first evidence that DENV causes translocation of mitofusins to mitochondria in the C6/36 mosquito cell line. Another protein Drp-1 (Dynamin-related protein 1) did not localize to mitochondria in DENV-infected cells. This observation therefore ruled out the possibility that the abovementioned alterations in mitochondrial function are associated with mitochondrial fission. In summary, this report provides some key insights into the virus-mitochondria crosstalk in DENV infected mosquito cells.crosstalk in DENV infected mosquito cells.)
Espino 2016 Abstract Mito Xmas Meeting Innsbruck + (Aequorin is a 22-kDa photoprotein produced … Aequorin is a 22-kDa photoprotein produced by the jellyfish ''Aequorea victoria'' that has been long utilised for the study of Ca2+ signaling [1]. It has been also engineered to induce its specific targeting to various cell regions so as to monitor [Ca2+] in different subcellular comparments, e.g., mitochondrial matrix [2]. Nevertheless, its potential applicability is somewhat limited owing to consumption or saturation of aequorin throughout the experiment as well as stability of aequorin at physiological temperature. Herein, in an attempt to overcome the aforementioned disadvantages, we have developed a mitochondria-targeted triple-mutated form (Asp119Ala, Gln168Arg and Leu170Ile) of the photoprotein aequorin that enables measurement of [Ca2+] in the millimolar range. In fact, it is shown that addition of extramitochondrial Ca2+ to permeabilized HeLa cells triggers an increase in mitochondrial [Ca2+] up to approximately 2 mM. In intact cells, the novel probe allows recording agonist-stimulated mitochondrial [Ca2+] rises without problems derived from aequorin saturation and/or consumption. Notably, in addition to the increased dynamic range, the Gln168Arg and Leu170Ile mutations endowed this new aequorin-based probe with an increased lifetime at 37°C. This also allowed the generation of a cell line stably expressing the probe at very high levels.lifetime at 37°C. This also allowed the generation of a cell line stably expressing the probe at very high levels.)
Eynon 2011 Physiol Genomics + (Aerobic ATP generation by the mitochondria … Aerobic ATP generation by the mitochondrial respiratory oxidative phosphorylation system (OXPHOS) is a vital metabolic process for endurance exercise. Notably, mitochondrial DNA (mtDNA) codifies 13 of the 83 polypeptides implied in the respiratory chain. As such, there is a strong rationale for identifying an association between mtDNA variants and "aerobic" (endurance) exercise phenotypes. The aim of this review is to summarize current knowledge on the association between mtDNA, nuclear genes involved in mitochondriogenesis, and elite endurance athletic status. Several studies in nonathletic people have demonstrated an association between certain mtDNA lineages and aerobic performance, characterized by maximal oxygen uptake (VO2max). Whether mtDNA haplogroups are also associated with the status of being an elite endurance athlete is more controversial, with differences between studies arising from the different ethnic backgrounds of the athletic cohorts (Caucasian of mixed geographic origin, Asiatic, or East African).graphic origin, Asiatic, or East African).)
Hunter 2019 J Appl Physiol (1985) + (Aerobic capacity is negatively related to … Aerobic capacity is negatively related to locomotion economy. The purpose of the paper is to determine what effects aerobic exercise training has on the relationship between net cycling oxygen uptake (inverse of economy) and aerobic capacity (VO2peak) as well as what role mitochondrial coupled and uncoupled respiration may play in whole body aerobic capacity and cycling economy.Cycling net oxygen uptake and VO2peak were evaluated on 52 subjects prior to exercise training (baseline) and 31 subjects after 8-16 weeks of aerobic training. Muscle tissue was collected from 25 subjects at baseline and 15 post training. Mitochondrial respiration assays were performed using High Resolution Respirometry.Pre (r=0.34, p<0.05) and post exercise training (r=0.62, p<0.01) VO2peak and cycling net oxygen uptake were related. In addition, uncoupled and coupled fat respiration were related both baseline (r=0.89, p<0.01) and post training (r=0.89, p<01). Post training coupled (r=0.74, p<0.01) and uncoupled carbohydrate respiration (r=0.52, p<05) were related to cycle net oxygen uptake. In addition, correlations between changes in VO2peak and changes in cycle net oxygen uptake persist after training, even after adjusting for changes in RQ (an index of fat oxidation).These results suggest that the negative relationship between locomotion economy and aerobic capacity is increased following exercise training. In addition, it is proposed that at least one of the primary factors influencing this relationship has its foundation within the mitochondria. Strong relationships between coupled and uncoupled respiration appear to be contributing factors for this relationship.tionships between coupled and uncoupled respiration appear to be contributing factors for this relationship.)
Hunter 2019 J Appl Physiol + (Aerobic capacity is negatively related to … Aerobic capacity is negatively related to locomotion economy. The purpose of this paper is to determine what effect aerobic exercise training has on the relationship between net cycling oxygen uptake (inverse of economy) and aerobic capacity [peak oxygen uptake (V̇o2peak)], as well as what role mitochondrial coupled and uncoupled respiration may play in whole body aerobic capacity and cycling economy. Cycling net oxygen uptake and ''V̇''o2peak were evaluated on 31 premenopausal women before exercise training (baseline) and after 8-16 wk of aerobic training. Muscle tissue was collected from 15 subjects at baseline and post-training. Mitochondrial respiration assays were performed using high-resolution respirometry. Pre- (''r'' = 0.46, ''P'' < 0.01) and postexercise training (''r'' = 0.62, ''P'' < 0.01) ''V̇''o2peak and cycling net oxygen uptake were related. In addition, uncoupled and coupled fat respiration were related both at baseline (''r'' = 0.62, ''P'' < 0.01) and post-training (''r'' = 0.89, ''P'' < 01). Post-training coupled (''r'' = 0.74, ''P'' < 0.01) and uncoupled carbohydrate respiration (''r'' = 0.52, ''P'' < 05) were related to cycle net oxygen uptake. In addition, correlations between ''V̇''o2peak and cycle net oxygen uptake persist both at baseline and after training, even after adjusting for submaximal cycle respiratory quotient (an index of fat oxidation). These results suggest that the negative relationship between locomotion economy and aerobic capacity is increased following exercise training. In addition, it is proposed that at least one of the primary factors influencing this relationship has its foundation within the mitochondria. Strong relationships between coupled and uncoupled respiration appear to be contributing factors for this relationship.NEW & NOTEWORTHY: The negative relationship between cycle economy and aerobic capacity is increased following exercise training. The strong relationship between coupled and uncoupled respiration, especially after training, appears to be contributing to this negative relationship between aerobic capacity and cycling economy, suggesting that mitochondrial economy is not increased following aerobic exercise training. These results are suggestive that training programs designed to improve locomotion economy should focus on changing biomechanics.mprove locomotion economy should focus on changing biomechanics.)
Dawson 2022 FASEB J + (Aerobic energy demands have led to the evo … Aerobic energy demands have led to the evolution of complex mitochondrial reticula in highly oxidative muscles, but the extent to which metabolic challenges can be met with adaptive changes in physiology of specific mitochondrial fractions remains unresolved. We examined mitochondrial mechanisms supporting adaptive increases in aerobic performance in deer mice (''Peromyscus maniculatus'') adapted to the hypoxic environment at high altitude. High-altitude and low-altitude mice were born and raised in captivity, and exposed as adults to normoxia or hypobaric hypoxia (12 kPa O2 for 6-8 weeks). Subsarcolemmal and intermyofibrillar mitochondria were isolated from the gastrocnemius, and a comprehensive substrate titration protocol was used to examine mitochondrial physiology and O2 kinetics by high-resolution respirometry and fluorometry. High-altitude mice had greater yield, respiratory capacity for oxidative phosphorylation, and O2 affinity (lower P50 ) of subsarcolemmal mitochondria compared to low-altitude mice across environments, but there were no species difference in these traits in intermyofibrillar mitochondria. High-altitude mice also had greater capacities of complex II relative to complexes I + II and higher succinate dehydrogenase activities in both mitochondrial fractions. Exposure to chronic hypoxia reduced reactive oxygen species (ROS) emission in high-altitude mice but not in low-altitude mice. Our findings suggest that functional changes in subsarcolemmal mitochondria contribute to improving aerobic performance in hypoxia in high-altitude deer mice. Therefore, physiological variation in specific mitochondrial fractions can help overcome the metabolic challenges of life at high altitude.fractions can help overcome the metabolic challenges of life at high altitude.)
Gnaiger 2005 Abstract MiP2005 + (Aerobic exercise and several aspects of li … Aerobic exercise and several aspects of life style influence mitochondrial respiratory function in human muscle, in addition to effects of age, gender and genetic background. In the present study, a significant part of the variability in respiration of human mitochondria [1] was explained by analysis of readily accessible background information on 25 healthy human subjects (19 males and 6 females; 22 to 46 years). Based on a novel multi-substrate/inhibitor protocol, this approach advances the functional analysis in mitochondrial physiology and pathology.A protocol for high-resolution respirometry (with two or three Oroboros Oxygraph-2k operated in parallel) was designed for quantification of mitochondrial respiratory capacities in permeabilized muscle fibers obtained from small needle biopsies (2 to 6 mg per run; 2 or 4 runs per subject). Cell membranes were selectively permeabilized [2], and lack of respiratory stimulation by cytochrome c indicated an intact outer mitochondrial membrane (Fig. 1). Measurements were performed at 30 °C in the range of 20 to 50 kPa oxygen pressure (210 to 530 µM), to avoid oxygen limitation [3]. In this range, autoxidation of ascorbate and TMPD was a linear function of oxygen, which was applied for correction of chemical background oxygen flux.ADP-stimulated respiration with malate+octanoylcarnitine (state OM3) was 46 % compared to further addition of glutamate (state GM3). An additive effect was exerted by parallel complex I+II electron input (the GS3/GM3 ratio was 1.6), since respiration with succinate/rotenone (S3) was only 1.1 times the state GM3 (Fig. 1). In a variation of this protocol, FCCP was titrated upon state GS3, yielding a further 44 % increase (and a corresponding GSu/GM3 ratio of 2.4). State GS3, therefore, reflects the capacity of the phosphorylation system, in agreement with results on isolated mitochondria [4]. The coupled state GS3 represents the physiologically relevant upper limit of respiration, providing parallel complex I and II input in accordance with an operational TCA cycle. The physiological excess capactiy of COX, expressed as the COX/GM3 ratio was 2.7, whereas the COX/GS3 ratio was 1.4. Respiratory adenylate control ratios were identical with octanoylcarnitie (OM3/OM2) and succinate (S3/S4o).State GS3 declined significantly as a function of body mass index (BMI; body weight/hight2) in the 19 males, which explained ~60 % of total variability. BMI was independent of age, as was the GS3 respiratory capacity. Fatty acid oxidation capacity (state OM3), however, declined significantly with age (males and females combined), thus extending a study on isolated mitochondria [1] to a surprisingly narrow range of ages. Consideration of BMI and age, therefore, improves the diagnostic resolution of functional mitochondrial respiratory analyses.tional mitochondrial respiratory analyses.)
Suhane 2013 Bio Open + (Aerobic glycolysis in transformed cells is … Aerobic glycolysis in transformed cells is an unique metabolic phenotype characterized by a hyperactivated glycolytic pathway even in the presence of oxygen. It is not clear if the onset of aerobic glycolysis is regulated by mitochondrial dysfunction and, if so, what the metabolic windows of opportunity available to control this metabolic switch (mitochondrial to glycolytic) landscape are in transformed cells. Here we report a genetically-defined model system based on the gene-silencing of a mitochondrial complex I subunit, NDUFS3, where we demonstrate the onset of metabolic switch in isogenic human embryonic kidney cells by differential expression of NDUFS3. By means of extensive metabolic characterization, we demonstrate that NDUFS3 gene silencing systematically introduces mitochondrial dysfunction thereby leading to the onset of aerobic glycolysis in a manner dependent on NDUFS3 protein levels. Furthermore, we show that the sustained imbalance in free radical dynamics is a necessary condition to sustain the observed metabolic switch in cell lines with the most severe NDUFS3 suppression. Together, our data reveal a novel role for mitochondrial complex I subunit NDUFS3 in regulating the degree of mitochondrial dysfunction in living cells, thereby setting a “metabolic threshold” for the observation of aerobic glycolysis phenotype within the confines of mitochondrial dysfunction.the confines of mitochondrial dysfunction.)
Jia 2018 Cells + (Aerobic glycolysis, also referred to as th … Aerobic glycolysis, also referred to as the Warburg effect, has been regarded as the dominant metabolic phenotype in cancer cells for a long time. More recently, it has been shown that mitochondria in most tumors are not defective in their ability to carry out oxidative phosphorylation (OXPHOS). Instead, in highly aggressive cancer cells, mitochondrial energy pathways are reprogrammed to meet the challenges of high energy demand, better utilization of available fuels and macromolecular synthesis for rapid cell division and migration. Mitochondrial energy reprogramming is also involved in the regulation of oncogenic pathways via mitochondria-to-nucleus retrograde signaling and post-translational modification of oncoproteins. In addition, neoplastic mitochondria can engage in crosstalk with the tumor microenvironment. For example, signals from cancer-associated fibroblasts can drive tumor mitochondria to utilize OXPHOS, a process known as the reverse Warburg effect. Emerging evidence shows that cancer cells can acquire a hybrid glycolysis/OXPHOS phenotype in which both glycolysis and OXPHOS can be utilized for energy production and biomass synthesis. The hybrid glycolysis/OXPHOS phenotype facilitates metabolic plasticity of cancer cells and may be specifically associated with metastasis and therapy-resistance. Moreover, cancer cells can switch their metabolism phenotypes in response to external stimuli for better survival. Taking into account the metabolic heterogeneity and plasticity of cancer cells, therapies targeting cancer metabolic dependency in principle can be made more effective.y in principle can be made more effective.)
Saura 2022 Proc Natl Acad Sci U S A + (Aerobic life is powered by membrane-bound … Aerobic life is powered by membrane-bound enzymes that catalyze the transfer of electrons to oxygen and protons across a biological membrane. Cytochrome c oxidase (CcO) functions as a terminal electron acceptor in mitochondrial and bacterial respiratory chains, driving cellular respiration and transducing the free energy from O2 reduction into proton pumping. Here we show that CcO creates orientated electric fields around a nonpolar cavity next to the active site, establishing a molecular switch that directs the protons along distinct pathways. By combining large-scale quantum chemical density functional theory (DFT) calculations with hybrid quantum mechanics/molecular mechanics (QM/MM) simulations and atomistic molecular dynamics (MD) explorations, we find that reduction of the electron donor, heme ''a'', leads to dissociation of an arginine (Arg438)-heme a3 D-propionate ion-pair. This ion-pair dissociation creates a strong electric field of up to 1 V Å-1 along a water-mediated proton array leading to a transient proton loading site (PLS) near the active site. Protonation of the PLS triggers the reduction of the active site, which in turn aligns the electric field vectors along a second, "chemical," proton pathway. We find a linear energy relationship of the proton transfer barrier with the electric field strength that explains the effectivity of the gating process. Our mechanism shows distinct similarities to principles also found in other energy-converting enzymes, suggesting that orientated electric fields generally control enzyme catalysis.fields generally control enzyme catalysis.)
Thoral 2021 Biol Lett + (Aerobic metabolism of aquatic ectotherms i … Aerobic metabolism of aquatic ectotherms is highly sensitive to fluctuating climates. Many mitochondrial traits exhibit phenotypic plasticity in response to acute variations in temperature and oxygen availability. These responses are critical for understanding the effects of environmental variations on aquatic ectotherms' performance. Using the European seabass, ''Dicentrarchus labrax'', we determined the effects of acute warming and deoxygenation ''in vitro'' on mitochondrial respiratory capacities and mitochondrial efficiency to produce ATP (ATP/O ratio). We show that acute warming reduced ATP/O ratio but deoxygenation marginally raised ATP/O ratio, leading to a compensatory effect of low oxygen availability on mitochondrial ATP/O ratio at high temperature. The acute effect of warming and deoxygenation on mitochondrial efficiency might be related to the leak of protons across the mitochondrial inner membrane, as the mitochondrial respiration required to counteract the proton leak increased with warming and decreased with deoxygenation. Our study underlines the importance of integrating the combined effects of temperature and oxygen availability on mitochondrial metabolism. Predictions on decline in performance of aquatic ectotherms owing to climate change may not be accurate, since these predictions typically look at respiratory capacity and ignore efficiency of ATP production.y and ignore efficiency of ATP production.)
Wone 2013 Comp Biochem Physiol A Mol Integr Physiol + (Aerobic metabolism of vertebrates is linke … Aerobic metabolism of vertebrates is linked to membrane fatty acid (FA) composition. Although the membrane pacemaker hypothesis posits that desaturation of FAs accounts for variation in resting or basal metabolic rate (BMR), little is known about the FA profiles that underpin variation in maximal metabolic rate (MMR). We examined membrane FA composition of liver and skeletal muscle in mice after seven generations of selection for increased MMR. In both liver and skeletal muscle, unsaturation index did not differ between control and high-MMR mice. We also examined membrane FA composition at the individual-level of variation. In liver, 18:0, 20:3 n-6, 20:4 n-6, and 22:6 n-3 FAs were significant predictors of MMR. In gastrocnemius muscle, 18:2 n-6, 20:4 n-6, and 22:6 n-3 FAs were significant predictors of MMR. In addition, muscle 16:1 n-7, 18:1 n-9, and 22:5 n-3 FAs were significant predictors of BMR, whereas no liver FAs were significant predictors of BMR. Our findings indicate that (i) individual variation in MMR and BMR appears to be linked to membrane FA composition in the skeletal muscle and liver, and (ii) FAs that differ between selected and control lines are involved in pathways that can affect MMR or BMR.ed in pathways that can affect MMR or BMR.)
Aragones 2009 Cell Metab + (Aerobic organisms developed mechanisms to … Aerobic organisms developed mechanisms to protect themselves against a shortage of oxygen (O(2)). Recent studies reveal that O(2) sensors, belonging to the novel class of 2-oxoglutarate dependent iron(ii)-dioxygenases, have more important roles in metabolism than anticipated. Here, we provide a "metabolo-centric" overview of the role of the PHD/FIH members of this family in metabolism, in particular on how they regulate O(2) supply and consumption, energy compensation and conservation, O(2) conformance and hypoxia tolerance, redox and pH homeostasis, and other vital metabolic processes with implications in health and disease. These insights may offer novel opportunities for the treatment of ischemic diseases.es for the treatment of ischemic diseases.)
Pena 2020 Int J Chronic Dis + (Aerobic training (AT) can support brain he … Aerobic training (AT) can support brain health in Alzheimer’s disease (AD); however, the role of resistance training (RT) in AD is not well established. Aside from direct effects on the brain, exercise may also regulate brain function through secretion of muscle-derived myokines. Aims. This study examined the effects of AT and RT on hippocampal BDNF and IGF-1 signaling, β-amyloid expression, and myokine cathepsin B in the triple transgenic (3xTg-AD) model of AD. 3xTg-AD mice were assigned to one of the following groups: sedentary (Tg), aerobic trained (Tg+AT, 9 wks treadmill running), or resistance trained (Tg+RT, 9 wks weighted ladder climbing) (''N''=10/group). Rotarod latency and strength were assessed pre- and posttraining. Hippocampus and skeletal muscle were collected after training and analyzed by high-resolution respirometry, ELISA, and immunoblotting. Tg+RT showed greater grip strength than Tg and Tg+AT at posttraining (''p''<0.01). Only Tg+AT improved rotarod peak latency (''p''<0.01). Hippocampal IGF-1 concentration was ~15 % greater in Tg+AT and Tg+RT compared to Tg (''p''<0.05); however, downstream signals of p-IGF-1R, p-Akt, p-MAPK, and p-GSK3β were not altered. Cathepsin B, hippocampal p-CREB and BDNF, and hippocampal mitochondrial respiration were not affected by AT or RT. β-Amyloid was ~30 % lower in Tg+RT compared to Tg (''p''<0.05). This data suggests that regular resistance training reduces β-amyloid in the hippocampus concurrent with increased concentrations of IGF-1. Both types of training offered distinct benefits, either by improving physical function or by modifying signals in the hippocampus. Therefore, inclusion of both training modalities may address central defects, as well as peripheral comorbidities in AD.al defects, as well as peripheral comorbidities in AD.)
Hansen 2022 Free Radic Biol Med + (Aerobic training can improve vascular endo … Aerobic training can improve vascular endothelial function ''in-vivo''. The aim of this study was to elucidate the mechanisms underlying this improvement in isolated human microvascular endothelial cells. Sedentary males, aged 57 ± 6 years completed 8 weeks of intense aerobic training. Resting muscle biopsies were obtained from the thigh muscle and used for isolation of endothelial cells (pre n = 23, post n = 16). The cells were analyzed for mitochondrial respiration, H2O2 emission, glycolysis, protein levels of antioxidants, NADPH oxidase, endothelial nitric oxide (NO) synthase and prostacyclin synthase (PGI2S). ''In-vivo'' microvascular function, assessed by acetylcholine infusion and arterial blood pressure were also determined. Endothelial mitochondrial respiration and H2O2 formation were similar before and after training whereas the expression of superoxide dismutase and the expression of glutathione peroxidase were 2.4-fold (p = 0.012) and 2.3-fold (p = 0.006) higher, respectively, after training. ''In-vivo'' microvascular function was increased by 1.4-fold (p = 0.036) in parallel with a 2.1-fold increase in endothelial PGI2S expression (p = 0.041). Endothelial cell glycolysis was reduced after training, as indicated by a 65% lower basal production of lactate (p = 0.003) and a 30% lower expression of phosphofructokinase (p = 0.011). Subdivision of the participants according to blood pressure at base-line (n = 23), revealed a 2-fold higher (p = 0.049) rate of H2O2 production in endothelial cells from hypertensive participants. Our data show that exercise training increases skeletal muscle microvascular endothelial cell metabolism, antioxidant capacity and the capacity to form prostacyclin. Moreover, elevated blood pressure is associated with increased endothelial mitochondrial ROS formation.the capacity to form prostacyclin. Moreover, elevated blood pressure is associated with increased endothelial mitochondrial ROS formation.)
DeLany 2014 J Clin Endocrinol Metab + (African-American women (AAW) have an incre … African-American women (AAW) have an increased risk of developing type 2 diabetes compared to Caucasian women (CW). Lower insulin sensitivity has been reported in AAW, but the reasons for this racial difference and the contributions of liver versus skeletal muscle are incompletely understood.We tested the hypothesis that young, non-obese AAW manifest lower insulin sensitivity specific to skeletal muscle, not liver, and is accompanied by lower skeletal muscle mitochondrial oxidative capacity. Participants and Main Outcome Measures: Twenty-two non-obese (BMI 22.7±3.1 kg/m2) AAW and twenty-two matched CW (BMI 22.7±3.1 kg/m2) underwent characterization of body composition, objectively-assessed habitual physical activity, and insulin sensitivity with euglycemic clamps and stable-isotope tracers. Skeletal muscle biopsies were performed for lipid content, fiber-typing, and mitochondrial measurements. Peripheral insulin sensitivity was 26% lower in AAW (''p''<0.01), but hepatic insulin sensitivity was similar between groups. Physical activity levels were similar between groups. Lower insulin sensitivity in AAW was not explained by total or central adiposity. Skeletal muscle triglyceride content was similar but mitochondrial content was lower in AAW. Mitochondrial respiration was 24% lower in AAW and correlated with skeletal muscle insulin sensitivity (''r''=0.33, ''p''<0.05).When compared to CW, AAW have similar hepatic insulin sensitivity, but a muscle phenotype characterized by both lower insulin sensitivity and lower mitochondrial oxidative capacity. These observations occur in the absence of obesity and are not explained by physical activity. The only factor associated with lower insulin sensitivity in AAW was mitochondrial oxidative capacity. Because exercise training improves both mitochondrial capacity and insulin sensitivity, we suggest that it may be of particular benefit as a strategy for diabetes prevention in AAW.y be of particular benefit as a strategy for diabetes prevention in AAW.)
Brooks 2022 J Physiol + (After a century, it's time to turn the pag … After a century, it's time to turn the page on understanding of lactate metabolism and appreciate that lactate shuttling is an important component of intermediary metabolism in vivo. Cell-cell and intracellular lactate shuttles fulfil purposes of energy substrate production and distribution, as well as cell signalling under fully aerobic conditions. Recognition of lactate shuttling came first in studies of physical exercise where the roles of driver (producer) and recipient (consumer) cells and tissues were obvious. Moreover, the presence of lactate shuttling as part of postprandial glucose disposal and satiety signalling has been recognized. Mitochondrial respiration creates the physiological sink for lactate disposal in vivo. Repeated lactate exposure from regular exercise results in adaptive processes such as mitochondrial biogenesis and other healthful circulatory and neurological characteristics such as improved physical work capacity, metabolic flexibility, learning, and memory. The importance of lactate and lactate shuttling in healthful living is further emphasized when lactate signalling and shuttling are dysregulated as occurs in particular illnesses and injuries. Like a phoenix, lactate has risen to major importance in 21st century biology. major importance in 21st century biology.)
Ornelas 2017 Cancer Metastasis Rev + (After more than a century, aspirin remains … After more than a century, aspirin remains one of the most commonly used drugs in western medicine. Although mainly used for its anti-thrombotic, anti-pyretic, and analgesic properties, a multitude of clinical studies have provided convincing evidence that regular, low-dose aspirin use dramatically lowers the risk of cancer. These observations coincide with recent studies showing a functional relationship between platelets and tumors, suggesting that aspirin's chemopreventive properties may result, in part, from direct modulation of platelet biology and biochemistry. Here, we present a review of the biochemistry and pharmacology of aspirin with particular emphasis on its cyclooxygenase-dependent and cyclooxygenase-independent effects in platelets. We also correlate the results of proteomic-based studies of aspirin acetylation in eukaryotic cells with recent developments in platelet proteomics to identify non-cyclooxygenase targets of aspirin-mediated acetylation in platelets that may play a role in its chemopreventive mechanism.y a role in its chemopreventive mechanism.)
Sumbalova 2022 Abstract Bioblast + (After overcoming COVID-19, some people dev … After overcoming COVID-19, some people develop a variety of mid- and long-term effects like fatigue, breathlessness, cognitive dysfunction as part of post COVID-19 condition. These symptoms might persist from the initial illness or develop after the recovery. Spa rehabilitation is recommended for patients with post COVID-19 syndrome. In our previous study deficit of CI-linked mitochondrial function and reduced endogenous coenzyme Q10 (CoQ10) concentration was found in platelets of non-hospitalized, non-vaccinated patients 3 – 6 weeks after acute COVID-19 [1].In this project we studied effects of mountain spa rehabilitation (MR) and MR combined with ubiquinol (reduced form of CoQ10) supplementation (MRQ) on pulmonary function, clinical and psychological symptoms, endogenous CoQ10 levels, and platelet mitochondrial bioenergetics of patients with post COVID-19 syndrome.In total, 36 patients with post COVID-19 syndrome and 15 healthy volunteers (control group) were included in the study. The patients acomplished mountain spa rehabilitation in Sanatorium of Dr. Guhr in Tatranská Polianka, High Tatras, Slovakia with individual therapeutic program including special respiratory physiotherapy procedures, mental well-being, nutrition counseling and adequate exercise therapy. Fourteen patients were on mountain spa rehabilitation (MR) lasting 16 – 18 days and 22 patients were on MR with simultaneous supplementation with ubiquinol (2x100 mg/day) lasting 16 – 18 days and on ubiquinol supplementation for next 12 – 14 days after leaving the spa. Pulmonary function by 6-minute walking test (6MWT), exercise dyspnea by Borg scale (BS), oxygen saturation (SpO2) and clinical symptoms by questionnaire were evaluated before and after 16 – 18 days of MR. Platelet bioenergetics by high-resolution respirometry, plasma TBARS concentration, and CoQ10 concentration in blood, plasma and platelets were evaluated before (MR1 and MRQ1 groups) and after MR (MR2 and MRQ2 groups), and additionally in 8 patients with CoQ10 supplementation 12 – 14 days after MR (MRQ3 group).Platelet mitochondrial Complex I (CI)-linked oxidative phosphorylation (OXPHOS) and electron transfer (ET) capacity was markedly reduced in patients with post COVID-19 syndrome vs the control group (Fig. 1). After 16 – 18 days of MR these parameters improved in both groups vs before MR. The improvement in the group of patients supplemented with ubiquinol was higher than in the non-supplemented group. CI-linked OXPHOS and ET capacity increased further after additional 12 – 14 days of CoQ10 supplementation at home (MRQ3 group).The CoQ10 concentration markedly raised after 16 – 18 days of supplementation with ubiquinol in platelets (+60%, p <0.0001), blood (+185%, p<0.0001), and plasma (+232%, p<0.0001) reflecting high bioavailability of supplemented CoQ10. The increase of platelet mitochondrial CI-linked OXPHOS and ET capacity correlated with the increase of CoQ10 in platelets and there was a trend to positive correlation between the improvement of pulmonary function and the increase of CoQ10 in platelets.These data show significant role of supplemented ubiquinol in acceleration of mitochondrial health regeneration in patients with post COVID-19 syndrome. Mountain spa rehabilitation with coenzyme Q10 supplementation could be recommended to the patients with post COVID-19 syndrome.# Sumbalová Z, Kucharská J, Palacka P, Rausová Z, Langsjoen P, Langsjoen AM, Gvozdjáková A (2022) Platelet mitochondrial function and endogenous coenzyme Q10 levels are reduced in patients after COVID-19. https://doi.org/10.4149/BLL_2022_002# [[SUIT-001 O2 ce-pce D004]]4]] )
Vaupel MiP2010 + (After several decades, the Pasteur-, Crabt … After several decades, the Pasteur-, Crabtree- and [[Warburg effect]]s have experienced a renaissance in current research. The interaction between [[glycolysis]] (i.e., the direct breakdown of glucose to lactate/lactic acid) and mitochondrial [[oxidative phosphorylation]] (i.e., glucose oxidation) was first described by Pasteur in 1857.n) was first described by Pasteur in 1857.)
Bustamante 2008 Neurochem Res + (Age related changes in brain cortex NO met … Age related changes in brain cortex NO metabolism were investigated in mitochondria and cytosolic extracts from youth to adulthood. Decreases of 19%, 40% and 71% in NO production were observed in mitochondrial fractions from 3, 7, and 14 months old rats, respectively, as compared with 1-month-old rats. Decreased nNOS protein expression in 14 months old rats was also observed in mitochondria as compared with the nNOS protein expression in 1-month-old rats. Low levels of eNOS protein expression close to the detection limits and no iNOS protein expression were significantly detected in mitochondrial fraction for both groups of age. NO production in the cytosolic extracts also showed a marked decreasing tendency, showing higher levels than those observed in mitochondrial fractions for all groups of age. In the cytosolic extracts, however, the levels were stabilized in adult animals from 7 to 14 months. nNOS protein expression showed a similar age-pattern in cytosolic extracts for both groups of age, while the protein expression pattern for eNOS was higher expressed in adult rats (14 months) than in young animals. As well as in mitochondrial extracts iNOS protein expression was not significantly detected in cytosolic extracts at any age. RT-PCR assays indicated increased levels of nNOS mRNA in 1-month-old rats as compared with 14 months old rats, showing a similar pattern to that one observed for protein nNOS expression. A different aged pattern was observed for eNOS mRNA expression, being lower in 1-month-old rats as compared with 14 months old animals. iNOS mRNA was very low expressed in both groups of age, showing a residual iNOS mRNA that was not significantly detected. State 3 respiration rates were 78% and 85% higher when succinate and malate-glutamate were used as substrates, respectively, in 14 months rats as compared with 1-month-old rats. No changes were observed in state 4 respiration rates. These results could indicate 1 that nNOS and eNOS mRNA and protein expression can be age-dependent, and confirmed the nNOS origin for the mitochondrial NOS. During rat growth, the respiratory function seems to be modulated by NO produced by the different NOS enzymes: nNOS, eNOS and mtNOS present in the cytosol and in the mitochondria.nt in the cytosol and in the mitochondria.)
Santanasto 2016 Exp Gerontol + (Age related declines in walking performanc … Age related declines in walking performance may be partly attributable to skeletal muscle mitochondrial dysfunction as mitochondria produce over 90% of ATP needed for movement and the capacity for oxidative phosphorylation decreases with age.Participants were from two studies: an ancillary to the Lifestyle Interventions and Independence for Elders (LIFE) Study (n=33), which recruited lower functioning participants (Short Physical Performance Battery [SPPB], 7.8±1.2), and the Study of Energy and Aging-Pilot (SEA, n=29), which enrolled higher functioning (SPPB, 10.8±1.4). Physical activity was measured objectively using the Actigraph accelerometer (LIFE) and SenseWear Pro armband (SEA). Phosphocreatine recovery following muscle contraction of the quadriceps was measured using (31)P magnetic resonance spectroscopy and ATPmax (mM ATP/s) was calculated. Walking performance was defined as time (s) to walk 400m at a usual-pace. The cross-sectional association between mitochondrial function and walking performance was assessed using multivariable linear regression.Participants were 77.6±5.3years, 64.2% female and 67.2% white. ATPmax was similar in LIFE vs. SEA (0.52±0.14 vs. 0.55±0.14, p=0.31), despite different function and activity levels (1.6±2.2 vs.77.4±73.3min of moderate activity/day, p<0.01). Higher ATPmax was related to faster walk-time in SEA (r(2)=0.19, p=0.02,); but not the LIFE (r(2)<0.01, p=0.74) cohort.Mitochondrial function was associated with walking performance in higher functioning, active older adults, but not lower functioning, sedentary older adults.t not lower functioning, sedentary older adults.)
Spendiff 2014 Abstract MiP2014 + (Age related loss of independence and mobil … Age related loss of independence and mobility and an ill health are largely associated with sarcopenia, for which a prominent explanation is mitochondrial damage. Increases in mitochondrial DNA (mtDNA) mutations and mitochondrial dysfunction have been reported in aging skeletal muscle [1,2]. Master athletes (MAs) continue training and competing well into old age and represent an prominent model of healthy muscle aging [3]. The cellular mechanisms facilitating this achievement are currently unknown. Given their remarkable aging trajectory, it is reasonable to hypothesize that MAs have superior mitochondrial function and indices of mtDNA integrity. 15 world class elite MAs and 14 age-sex matched none-athlete controls (NAC), all over the age of 75, underwent muscle MRI scans to assess muscle mass and a biopsy of the vastus lateralis. mtDNA integrity was assessed using the duel cytochrome ''c'' oxidase/succinate dehydrogenase stain to ascertain the number of fibres with a respiratory system defect (RSD) and QPCR to provide an indication of mtDNA deletions and copy number. Three aspects of mitochondrial function were assessed in permeabilized myofibres: ROS production, respiration and calcium retention capacity. MAs had significantly more muscle mass than their sedentary counterparts, fewer myofibres with a RSD and an increased mtDNA copy number. However, there were very few differences in any of the three aspects of mitochondrial function examined. Therefore, while MAs have less RSD than NACs at the individual fibre level, this is not sufficient to result in an improvement in mitochondrial function, when studied at the whole muscle level. Thus a superior mitochondrial profile probably does not explain MAs’ remarkable muscle aging trajectory. However, in the presence of age related comorbidities the increased RSD may result in an exacerbation of these conditions in NACs. This data raises questions regarding the impact of age related mitochondrial changes on the muscle, as MAs, with the same level of mitochondrial function as controls, still displayed remarkable strength.rols, still displayed remarkable strength.)
Hashizume 2015 Sci Rep + (Age-associated accumulation of somatic mut … Age-associated accumulation of somatic mutations in mitochondrial DNA (mtDNA) has been proposed to be responsible for the age-associated mitochondrial respiration defects found in elderly human subjects. We carried out reprogramming of human fibroblast lines derived from elderly subjects by generating their induced pluripotent stem cells (iPSCs), and examined another possibility, namely that these aging phenotypes are controlled not by mutations but by epigenetic regulation. Here, we show that reprogramming of elderly fibroblasts restores age-associated mitochondrial respiration defects, indicating that these aging phenotypes are reversible and are similar to differentiation phenotypes in that both are controlled by epigenetic regulation, not by mutations in either the nuclear or the mitochondrial genome. Microarray screening revealed that epigenetic downregulation of the nuclear-coded GCAT gene, which is involved in glycine production in mitochondria, is partly responsible for these aging phenotypes. Treatment of elderly fibroblasts with glycine effectively prevented the expression of these aging phenotypes. the expression of these aging phenotypes.)
Bhaskaran 2020 Aging Cell + (Age-associated loss of muscle mass and fun … Age-associated loss of muscle mass and function (sarcopenia) has a profound effect on the quality of life in the elderly. Our previous studies show that CuZnSOD deletion in mice (Sod1-/- mice) recapitulates sarcopenia phenotypes, including elevated oxidative stress and accelerated muscle atrophy, weakness, and disruption of neuromuscular junctions (NMJs). To determine whether deletion of Sod1 initiated in neurons in adult mice is sufficient to induce muscle atrophy, we treated young (2- to 4-month-old) Sod1flox/SlickHCre mice with tamoxifen to generate i-mn-Sod1KO mice. CuZnSOD protein was 40-50% lower in neuronal tissue in i-mn-Sod1KO mice. Motor neuron number in ventral spinal cord was reduced 28% at 10 months and more than 50% in 18- to 22-month-old i-mn-Sod1KO mice. By 24 months, 22% of NMJs in i-mn-Sod1KO mice displayed a complete lack of innervation and deficits in specific force that are partially reversed by direct muscle stimulation, supporting the loss of NMJ structure and function. Muscle mass was significantly reduced by 16 months of age and further decreased at 24 months of age. Overall, our findings show that neuronal-specific deletion of CuZnSOD is sufficient to cause motor neuron loss in young mice, but that NMJ disruption, muscle atrophy, and weakness are not evident until past middle age. These results suggest that loss of innervation is critical but may not be sufficient until the muscle reaches a threshold beyond which it cannot compensate for neuronal loss or rescue additional fibers past the maximum size of the motor unit.tional fibers past the maximum size of the motor unit.)
Bose 2020 Aging Cell + (Age-associated mitochondrial dysfunction a … Age-associated mitochondrial dysfunction and oxidative damage are primary causes for multiple health problems including sarcopenia and cardiovascular disease (CVD). Though the role of Nrf2, a transcription factor that regulates cytoprotective gene expression, in myopathy remains poorly defined, it has shown beneficial properties in both sarcopenia and CVD. Sulforaphane (SFN), a natural compound Nrf2-related activator of cytoprotective genes, provides protection in several disease states including CVD and is in various stages of clinical trials, from cancer prevention to reducing insulin resistance. This study aimed to determine whether SFN may prevent age-related loss of function in the heart and skeletal muscle. Cohorts of 2-month-old and 21- to 22-month-old mice were administered regular rodent diet or diet supplemented with SFN for 12 weeks. At the completion of the study, skeletal muscle and heart function, mitochondrial function, and Nrf2 activity were measured. Our studies revealed a significant drop in Nrf2 activity and mitochondrial functions, together with a loss of skeletal muscle and cardiac function in the old control mice compared to the younger age group. In the old mice, SFN restored Nrf2 activity, mitochondrial function, cardiac function, exercise capacity, glucose tolerance, and activation/differentiation of skeletal muscle satellite cells. Our results suggest that the age-associated decline in Nrf2 signaling activity and the associated mitochondrial dysfunction might be implicated in the development of age-related disease processes. Therefore, the restoration of Nrf2 activity and endogenous cytoprotective mechanisms by SFN may be a safe and effective strategy to protect against muscle and heart dysfunction due to aging.muscle and heart dysfunction due to aging.)
Dias 2016 Neurobiol Aging + (Age-dependent changes in nitric oxide ((•) … Age-dependent changes in nitric oxide ((•)NO) concentration dynamics may play a significant role in both decaying synaptic and metabolic functions in Alzheimer's disease (AD). This neuromodulator acts presynaptically to increase vesicle release and glutamatergic transmission and also regulates mitochondrial function. Under conditions of altered intracellular redox environment, (•)NO may react and produce reactive species such as peroxynitrite. Using the triple transgenic mouse model of AD (3xTgAD), we investigated age-dependent changes in the glutamate-(•)NO axis in the hippocampus. Direct measurement of (•)NO concentration dynamics revealed a significant increase in N-methyl-D-aspartate type receptor-evoked peak (•)NO in the 3xTgAD model at an early age. Aging produced a decrease in peak (•)NO accompanied by significant decrease in production and decay rates in the transgenic model. Evaluation of energy metabolism revealed age-dependent decrease in basal oxygen consumption rate, a general decrease in mitochondrial oxidative phosphorylation parameters, and loss in mitochondrial sparing capacity in both genotypes. Finally, we observed age-dependent increase in 3-nitrotyrosine residues in the hippocampus, consistent with a putative shift in (•)NO bioactivity toward oxidative chemistry associated with neurotoxicity.Copyright © 2016 Elsevier Inc. All rights reserved. © 2016 Elsevier Inc. All rights reserved.)
Gioscia-Ryan 2015 Abstract MiPschool Greenville 2015 + (Age-related arterial endothelial dysfuncti … Age-related arterial endothelial dysfunction, characterized by a decline in endothelium-dependent dilation (EDD), is mediated largely by oxidative stress. Excessive levels of mitochondria-derived reactive oxygen species (mtROS), a hallmark of mitochondrial dysfunction, are an important contributor to tonic arterial oxidative stress-mediated suppression of EDD with aging [1]. In addition to baseline deficits in arterial function, aging may also be accompanied by reduced arterial resilience, i.e., the ability to withstand stress. Aging exacerbates the effects of common stressors such as a “Western”-style (high fat/high sugar) diet, hyperglycemia, and elevated low-density lipoprotein (LDL) cholesterol, such that the age- and stressor-associated impairments in arterial function are compounded [2]. However, whether declines in arterial mitochondrial health contribute to decreased resilience with aging is unknown. Aerobic exercise is a powerful intervention that restores baseline endothelial function with aging and improves mitochondrial health in many non-vascular tissues but the effects of exercise on arterial resilience and mitochondrial health with primary aging are unexplored. We tested the hypothesis that aging would be associated with reduced arterial mitochondrial health and impaired arterial resilience to acute stress, and that voluntary aerobic exercise initiated in late life would improve arterial mitochondrial health and increase resilience of aging arteries. Young (5 mo) and old (25 mo) male C57BL/6 mice were randomly assigned to either a sedentary cage control group (young and old control [YC, n=11 and OC, n=12]) or a voluntary aerobic exercise group (young and old voluntary wheel running [YVR, n=10 and OVR, n=11] for 10 weeks. After 10 weeks, endothelial function was assessed in isolated carotid arteries as EDD in response to increasing doses of acetylcholine (ACh). Arterial resilience was determined as the change in EDD response with ACh alone versus following acute application of a mitochondrial stressor (rotenone 0.5 µM, 40 min [1]) or a simulated “Western Diet (WD)” stressor (8 mM glucose + 160 µM palmitate; 40 min intraluminal infusion). The contribution of mtROS to the “WD” stress was determined by assessing EDD with “WD” in the presence of the mitochondria-specific antioxidant MitoQ (1 µM) [3]. Arterial mtROS production was assessed in aortic segments via electron paramagnetic resonance with the mitochondrial superoxide-specific spin probe mitoTEMPO-H. Arterial protein markers of mitochondrial health (PGC-1α, SIRT-3, Fis-1 [TTC11]) were assessed by Western blotting (normalized to GAPDH).by Western blotting (normalized to GAPDH).)
Pharaoh 2019 Mol Neurobiol + (Age-related decline in circulating levels … Age-related decline in circulating levels of insulin-like growth factor (IGF)-1 is associated with reduced cognitive function, neuronal aging, and neurodegeneration. Decreased mitochondrial function along with increased reactive oxygen species (ROS) and accumulation of damaged macromolecules are hallmarks of cellular aging. Based on numerous studies indicating pleiotropic effects of IGF-1 during aging, we compared the central and peripheral effects of circulating IGF-1 deficiency on tissue mitochondrial function using an inducible liver IGF-1 knockout (LID). Circulating levels of IGF-1 (~ 75%) were depleted in adult male Igf1f/f mice via AAV-mediated knockdown of hepatic IGF-1 at 5 months of age. Cognitive function was evaluated at 18 months using the radial arm water maze and glucose and insulin tolerance assessed. Mitochondrial function was analyzed in hippocampus, muscle, and visceral fat tissues using high-resolution respirometry O2K as well as redox status and oxidative stress in the cortex. Peripherally, IGF-1 deficiency did not significantly impact muscle mass or mitochondrial function. Aged LID mice were insulin resistant and exhibited ~ 60% less adipose tissue but increased fat mitochondrial respiration (20%). The effects on fat metabolism were attributed to increases in growth hormone. Centrally, IGF-1 deficiency impaired hippocampal-dependent spatial acquisition as well as reversal learning in male mice. Hippocampal mitochondrial OXPHOS coupling efficiency and cortex ATP levels (~ 50%) were decreased and hippocampal oxidative stress (protein carbonylation and F2-isoprostanes) was increased. These data suggest that IGF-1 is critical for regulating mitochondrial function, redox status, and spatial learning in the central nervous system but has limited impact on peripheral (liver and muscle) metabolism with age. Therefore, IGF-1 deficiency with age may increase sensitivity to damage in the brain and propensity for cognitive deficits. Targeting mitochondrial function in the brain may be an avenue for therapy of age-related impairment of cognitive function. Regulation of mitochondrial function and redox status by IGF-1 is essential to maintain brain function and coordinate hippocampal-dependent spatial learning. While a decline in IGF-1 in the periphery may be beneficial to avert cancer progression, diminished central IGF-1 signaling may mediate, in part, age-related cognitive dysfunction and cognitive pathologies potentially by decreasing mitochondrial function.gies potentially by decreasing mitochondrial function.)
Egerman 2015 Cell Metab + (Age-related frailty may be due to decrease … Age-related frailty may be due to decreased skeletal muscle regeneration. The role of TGF-β molecules myostatin and GDF11 in regeneration is unclear. Recent studies showed an age-related decrease in GDF11 and that GDF11 treatment improves muscle regeneration, which were contrary to prior studies. We now show that these recent claims are not reproducible and the reagents previously used to detect GDF11 are not GDF11 specific. We develop a GDF11-specific immunoassay and show a trend toward increased GDF11 levels in sera of aged rats and humans. GDF11 mRNA increases in rat muscle with age. Mechanistically, GDF11 and myostatin both induce SMAD2/3 phosphorylation, inhibit myoblast differentiation, and regulate identical downstream signaling. GDF11 significantly inhibited muscle regeneration and decreased satellite cell expansion in mice. Given early data in humans showing a trend for an age-related increase, GDF11 could be a target for pharmacologic blockade to treat age-related sarcopenia. blockade to treat age-related sarcopenia.)
Andersson 2011 Cell Metab + (Age-related loss of muscle mass and force … Age-related loss of muscle mass and force (sarcopenia) contributes to disability and increased mortality. Ryanodine receptor 1 (RyR1) is the skeletal muscle sarcoplasmic reticulum calcium release channel required for muscle contraction. RyR1 from aged (24 months) rodents was oxidized, cysteine-nitrosylated, and depleted of the channel-stabilizing subunit calstabin1, compared to RyR1 from younger (3-6 months) adults. This RyR1 channel complex remodeling resulted in "leaky" channels with increased open probability, leading to intracellular calcium leak in skeletal muscle. Similarly, 6-month-old mice harboring leaky RyR1-S2844D mutant channels exhibited skeletal muscle defects comparable to 24-month-old wild-type mice. Treating aged mice with S107 stabilized binding of calstabin1 to RyR1, reduced intracellular calcium leak, decreased reactive oxygen species (ROS), and enhanced tetanic Ca(2+) release, muscle-specific force, and exercise capacity. Taken together, these data indicate that leaky RyR1 contributes to age-related loss of muscle function.es to age-related loss of muscle function.)
Joseph 2012 Aging Cell + (Age-related loss of muscle mass and streng … Age-related loss of muscle mass and strength (sarcopenia) leads to a decline in physical function and frailty in the elderly. Among the many proposed underlying causes of sarcopenia, mitochondrial dysfunction is inherent in a variety of aged tissues. The intent of this study was to examine the effect of aging on key groups of regulatory proteins involved in mitochondrial biogenesis and how this relates to physical performance in two groups of sedentary elderly participants, classified as high- and low-functioning based on the Short Physical Performance Battery test. Muscle mass was decreased by 38% and 30% in low-functioning elderly (LFE) participants when compared to young and high-functioning elderly (HFE) participants, respectively, and positively correlated to physical performance. Mitochondrial respiration in permeabilized muscle fibers was reduced (41%) in the LFE group when compared to the young, and this was associated with a 30% decline in COX activity. Levels of key metabolic regulators, SIRT3 and [[PGC-1α]] were significantly reduced (50%) in both groups of elderly participants when compared to young. Similarly, the fusion protein OPA1 was lower in muscle from elderly subjects, however no changes were detected in Mfn2, Drp1 or Fis1 among the groups. In contrast, protein import machinery (PIM) components Tom22 and cHsp70 were increased in the LFE group when compared to the young. This study suggests that aging in skeletal muscle is associated with impaired mitochondrial function and altered biogenesis pathways, and that this may contribute to muscle atrophy and the decline in muscle performance observed in the elderly population.rmance observed in the elderly population.)
Ahn 2018 Redox Biol + (Age-related loss of skeletal muscle mass and contractile dysfunction, or sarcopenia, reduces independence and quality of life in the elderly and leads to increased risk of comorbidities...)
Ahn 2022 Aging Cell + (Age-related muscle atrophy and weakness, o … Age-related muscle atrophy and weakness, or sarcopenia, are significant contributors to compromised health and quality of life in the elderly. While the mechanisms driving this pathology are not fully defined, reactive oxygen species, neuromuscular junction (NMJ) disruption, and loss of innervation are important risk factors. The goal of this study is to determine the impact of mitochondrial hydrogen peroxide on neurogenic atrophy and contractile dysfunction. Mice with muscle-specific overexpression of the mitochondrial H2O2 scavenger peroxiredoxin3 (mPRDX3) were crossed to Sod1KO mice, an established mouse model of sarcopenia, to determine whether reduced mitochondrial H2O2 can prevent or delay the redox-dependent sarcopenia. Basal rates of H2O2 generation were elevated in isolated muscle mitochondria from Sod1KO, but normalized by mPRDX3 overexpression. The mPRDX3 overexpression prevented the declines in maximum mitochondrial oxygen consumption rate and calcium retention capacity in Sod1KO. Muscle atrophy in Sod1KO was mitigated by ~20% by mPRDX3 overexpression, which was associated with an increase in myofiber cross-sectional area. With direct muscle stimulation, maximum isometric specific force was reduced by ~20% in Sod1KO mice, and mPRDX3 overexpression preserved specific force at wild-type levels. The force deficit with nerve stimulation was exacerbated in Sod1KO compared to direct muscle stimulation, suggesting NMJ disruption in Sod1KO. Notably, this defect was not resolved by overexpression of mPRDX3. Our findings demonstrate that muscle-specific PRDX3 overexpression reduces mitochondrial H2O2 generation, improves mitochondrial function, and mitigates loss of muscle quantity and quality, despite persisting NMJ impairment in a murine model of redox-dependent sarcopenia.ion, and mitigates loss of muscle quantity and quality, despite persisting NMJ impairment in a murine model of redox-dependent sarcopenia.)
Paeaesuke 2015 Oxid Med Cell Longev + (Ageing is associated with suppressed regen … Ageing is associated with suppressed regenerative potential of muscle precursor cells due to decrease of satellite cells and suppressive intramuscular milieu on their activation, associated with ageing-related low-grade inflammation. The aim of the study was to characterize the function of oxidative phosphorylation (OXPHOS), glycolysis, adenylate kinase (AK), and creatine kinase (CK)-mediated systems in young and older individuals.Myoblasts were cultivated from biopsies taken by transcutaneous conchotomy from ''vastus lateralis'' muscle in young (20-29 yrs, n=7) and older (70-79 yrs, n=7) subjects. Energy metabolism was assessed in passages 2 to 6 by oxygraphy and enzyme analysis.In myoblasts of young and older subjects the rate of OXPHOS decreased during proliferation from passage 2 to 6. The total activities of CK and AK decreased. Myoblasts of passage 2 cultivated from young muscle showed higher rate of OXPHOS and activities of CK and AK compared to myoblasts from older subjects while hexokinase and pyruvate kinase were not affected by ageing.Proliferation of myoblasts ''in vitro'' is associated with down-regulation of OXPHOS and energy storage and transfer systems. Ageing ''in vivo'' exerts an impact on satellite cells which results in altered metabolic profile in favour of the prevalence of glycolytic pathways over mitochondrial OXPHOS of myoblasts.ys over mitochondrial OXPHOS of myoblasts.)
Paju 2014 Abstract MiP2014 + (Ageing is frequently associated with sarco … Ageing is frequently associated with sarcopenia, which has been attributed to low grade inflammation, suppressed regenerative potential of muscle precursor cells and homeostatic changes in the niches of satellite cells of old persons [1,2]. The aim of this study was to investigate mitochondrial function in primary cell cultures, derived from biopsies taken from young and old individuals.Primary muscle cell culture myoblasts, obtained from biopsies of vastus lateralis in young (19-29 y) and old (70-80 y) subjects, were purified with CD56 antibody microbeads on MACS and cultured in the presence of HGF. The cultures were stimulated with differentiation media supplement, insulin-transferrin-sodium selenite (ITS), for 6 days with one of cytokines IL1, IL6 or TNF-α. The function of respiratory complexes (OXPHOS) was assessed by high-resolution respirometry.The myoblasts cultivated from old individuals differentiated into myotubes markedly slower than myoblasts from young individuals in ITS medium (''P''<0.0001). The effect of IL-6 depended on donor age, as its effect on myoblast differentiation decreased with age. Treatment of human myoblasts with TNF-α and IL-1β increased the proliferation and blocked differentiation in the presence of ITS. The inhibitory effect of TNF-α and IL-1β on myotubes formation was mediated by down-regulation of mRNA levels of myogenin and muscle-specific isoforms of CK (CKM and CKMT2). The data on mitochondrial respiration revealed that IL-1β caused a significant decrease in mitochondrial Complex I- and II-linked respiration, normalized on cell protein content both in the myotubes of old and young individuals. This action of IL1-β was not seen when the respiratory results were normalized on citrate synthase activity, revealing the role of a decrease in mitochondrial content in these cells. TNF-α, on the contrary, caused a significant increase in mitochondrial Complex I- and II-linked respiration, normalized on protein in myotubes of old and young subjects. This action of TNF-α remained significant when respiration was normalized on citrate synthase activity. The mode of action of these pro-inflammatory cytokines on OXPHOS of muscle cell cultures was the same in both groups, young and old persons.Our data suggest that the myoblasts cultivated from biopsies of old individuals differentiate into myotubes slower than those from young individuals. The actions of pro-inflammatory cytokines on OXPHOS level of these cell cultures are different: IL-1β decreased, TNF-α stimulated but IL-6 exerted no alteration on OXPHOS activity, both in old or young individuals. The OXPHOS capacity in myogenic cell culture depends more on the mode of action of cytokine than the donor’s age.e of action of cytokine than the donor’s age.)
Gnaiger 2012 Abstract-FEPS-Santiago de Compostela + (Aging implicates a progressive decline in … Aging implicates a progressive decline in muscle mass and strength (sarcopenia) which is counteracted by strength training, and a decline of aerobic performance (muscle fatigability, reduced aerobic capacity and loss of mitochondrial power or OXPHOS capacity in muscle tissue). OXPHOS capacity is increased or maintained high by a life style involving endurance exercise and strength training [1]. Life style changes from the age of 20-30 years to the elderly, but is subject to change and intervention. Depending on group selection in cross-sectional studies, OXPHOS capacity declines from the age of 20-30 years [2,3], or is independent of age up to 80 years [4,5]. Independent of age, there is a strong decline of OXPHOS capacity in human vastus lateralis from BMI of 20 to 30 [6]. The relationship between BMI, training and OXPHOS capacity is also observed in horse skeletal muscle [7]. At a BMI >30, a minimum OXPHOS capacity is reached in human v. lateralis that may be characteristic of a low-grade inflammatory state (‘mitochondrial fever’). Onset of degenerative diseases (diabetes 2, neuromuscular degeneration, various cancers) and mitochondrial dysfunction interact in an amplification loop progressing slowly with age, such that cause and effect of mitochondrial dysfunction cannot be distinguished. Diminished antioxidant capacity at low mitochondrial density is an important mechanistic candidate in the state of mitochondrial fever.Contribution to K-Regio ''[[MitoCom_O2k-Fluorometer|MitoCom Tyrol]]''. # [[Pesta_2011_Am J Physiol Regul Integr Comp Physiol|Pesta D, Hoppel F, Macek C, Messner H, Faulhaber M, Kobel C, Parson W, Burtscher M, Schocke M, Gnaiger E (2011) Similar qualitative and quantitative changes of mitochondrial respiration following strength and endurance training in normoxia and hypoxia in sedentary humans. Am J Physiol Regul Integr Comp Physiol 301:R1078–87.]]# Short KR, Bigelow ML, Kahl J, Singh R, Coenen-Schimke J, Raghavakaimal S, Nair KS (2005) Decline in skeletal muscle mitochondrial function with aging in humans. Proc Natl Acad Sci U S A 102:5618-23.# [[Joseph 2012 Aging Cell|Joseph AM, Adhihetty PJ, Buford TW, Wohlgemuth SE, Lees HA, Nguyen LM, Aranda JM, Sandesara BD, Pahor M, Manini TM, Marzetti E, Leeuwenburgh C (2012) The impact of aging on mitochondrial function and biogenesis pathways in skeletal muscle of sedentary high- and low-functioning elderly individuals. Aging Cell 11:801-9.]]# Lanza IR, Short DK, Short KR, Raghavakaimal S, Basu R, Joyner MJ, McConnell JP, Nair KS (2008) Endurance exercise as a countermeasure for aging. Diabetes 57:2933-42.# [[Larsen 2012 Acta Physiol (Oxf)|Larsen S, Hey-Mogensen M, Rabol R, Stride N, Helge JW, Dela F (2012) The influence of age and aerobic fitness: Effects on mitochondrial respiration in skeletal muscle. Acta Physiol (Oxf) 205:423-32.]]# [[Gnaiger 2009 Int J Biochem Cell Biol|Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int J Biochem Cell Biol 41:1837–45.]]# [[Votion_2012_PLoS One|Votion DM, Gnaiger E, Lemieux H, Mouithys-Mickalad A, Serteyn D (2012) Physical fitness and mitochondrial respiratory capacity in horse skeletal muscle. PLoS One 7:e34890.]]_2012_PLoS One|Votion DM, Gnaiger E, Lemieux H, Mouithys-Mickalad A, Serteyn D (2012) Physical fitness and mitochondrial respiratory capacity in horse skeletal muscle. PLoS One 7:e34890.]])
Reis 2016 Aging (Albany NY) + (Aging increases the risk of type 2 diabete … Aging increases the risk of type 2 diabetes, and this can be prevented by dietary restriction (DR). We have previously shown that DR inhibits the downregulation of miRNAs and their processing enzymes - mainly Dicer - that occurs with aging in mouse white adipose tissue (WAT). Here we used fat-specific Dicer knockout mice (AdicerKO) to understand the contributions of adipose tissue Dicer to the metabolic effects of aging and DR. Metabolomic data uncovered a clear distinction between the serum metabolite profiles of Lox control and AdicerKO mice, with a notable elevation of branched-chain amino acids (BCAA) in AdicerKO. These profiles were associated with reduced oxidative metabolism and increased lactate in WAT of AdicerKO mice and were accompanied by structural and functional changes in mitochondria, particularly under DR. AdicerKO mice displayed increased mTORC1 activation in WAT and skeletal muscle, where Dicer expression is not affected. This was accompanied by accelerated age-associated insulin resistance and premature mortality. Moreover, DR-induced insulin sensitivity was abrogated in AdicerKO mice. This was reverted by rapamycin injection, demonstrating that insulin resistance in AdicerKO mice is caused by mTORC1 hyperactivation. Our study evidences a DR-modulated role for WAT Dicer in controlling metabolism and insulin resistance.rolling metabolism and insulin resistance.)
Gregg 2016 Diabetes + (Aging is accompanied by impaired glucose h … Aging is accompanied by impaired glucose homeostasis and an increased risk of type 2 diabetes, culminating in the failure of insulin secretion from pancreatic β cells. To investigate the effects of age on β cell metabolism, we established a novel assay to directly image islet metabolism using NAD(P)H fluorescence lifetime imaging (FLIM). We determined that impaired mitochondrial activity underlies an age-dependent loss of insulin secretion in human islets. NAD(P)H FLIM revealed a comparable decline in mitochondrial function in the pancreatic islets of aged mice (≥ 24 months), resulting from 52% and 57% defects in flux through complex I and II of the electron transport chain. However, insulin secretion and glucose tolerance are preserved in aged mouse islets by the heightened metabolic sensitivity of the β cell triggering pathway, an adaptation clearly encoded in the metabolic and Ca2+ oscillations that trigger insulin release (Ca2+ plateau fraction: young, 0.211 ± 0.006; aged, 0.380 ± 0.007, P < 0.0001). This enhanced sensitivity is driven by a reduction in KATP channel conductance (diazoxide: young, 5.1 ± 0.2 nS; aged, 3.5 ± 0.5 nS, P < 0.01), resulting in a ∼2.8 mM left shift in the β cell glucose threshold. Our results demonstrate how mice, but not humans, are able to successfully compensate for age-associated metabolic dysfunction by adjusting their β cell glucose sensitivity, and highlight an essential mechanism for ensuring the maintenance of insulin secretion.© 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.perly cited, the use is educational and not for profit, and the work is not altered.)
Goetzman 2023 Antioxidants (Basel) + (Aging is associated with a decline in mito … Aging is associated with a decline in mitochondrial function which may contribute to age-related diseases such as neurodegeneration, cancer, and cardiovascular diseases. Recently, mitochondrial Complex II has emerged as an important player in the aging process. Mitochondrial Complex II converts succinate to fumarate and plays an essential role in both the tricarboxylic acid (TCA) cycle and the electron transport chain (ETC). The dysfunction of Complex II not only limits mitochondrial energy production; it may also promote oxidative stress, contributing, over time, to cellular damage, aging, and disease. Intriguingly, succinate, the substrate for Complex II which accumulates during mitochondrial dysfunction, has been shown to have widespread effects as a signaling molecule. Here, we review recent advances related to understanding the function of Complex II, succinate signaling, and their combined roles in aging and aging-related diseases.roles in aging and aging-related diseases.)
Eisenberg 2016 Nat Med + (Aging is associated with an increased risk … Aging is associated with an increased risk of cardiovascular disease and death. Here we show that oral supplementation of the natural polyamine spermidine extends the lifespan of mice and exerts cardioprotective effects, reducing cardiac hypertrophy and preserving diastolic function in old mice. Spermidine feeding enhanced cardiac autophagy, mitophagy and mitochondrial respiration, and it also improved the mechano-elastical properties of cardiomyocytes ''in vivo'', coinciding with increased titin phosphorylation and suppressed subclinical inflammation. Spermidine feeding failed to provide cardioprotection in mice that lack the autophagy-related protein Atg5 in cardiomyocytes. In Dahl salt-sensitive rats that were fed a high-salt diet, a model for hypertension-induced congestive heart failure, spermidine feeding reduced systemic blood pressure, increased titin phosphorylation and prevented cardiac hypertrophy and a decline in diastolic function, thus delaying the progression to heart failure. In humans, high levels of dietary spermidine, as assessed from food questionnaires, correlated with reduced blood pressure and a lower incidence of cardiovascular disease. Our results suggest a new and feasible strategy for protection against cardiovascular disease.protection against cardiovascular disease.)
Boushel 2014 Pro Can Soc Exercise Physiol + (Aging is associated with diminished cardio … Aging is associated with diminished cardiovascular function and sarcopenia, and loss of muscle oxidative capacity is considered a salient feature of aging. While moderate-to-high intensity training evokes mitochondrial biogenesis in skeletal muscle, it remains unclear to what extent aging in itself or rather a lower training stimulus that accompanies aging contributes to loss of skeletal muscle mitochondrial function. To address this question leg muscle mitochondrial respiratory capacity in 8 older men (65±2 yrs) who had maintained road cycling training 200 km/week for 50 years was compared to that of 8 age-matched sedentary (UT) controls (67±1 yrs).V˙ O2 max was measured on a bicycle ergometer and a biopsy obtained from vastus lateralis muscle was permeabilized and prepared for high resolution respirometry (Oxygraph, Oroboros, AT). V˙ O2 max was substantially higher (p<0.05) in lifelong trained (45±2 ml/kg/min) compared to UT (27±2 ml/kg/min). Mitochondrial LEAK respiration was higher in ET, and Vmax of mitochondrial respiration (OXPHOS) with mixed substrates was 2-fold higher in the ET (132±6 pmol/sec/mg) compared to UT (72±4 pmol/sec/mg, p<0.01). Higher fatty acid oxidation and substrate control ratios in ET indicate regulatory changes in mitochondria in addition to a larger mitochondrial volume. The findings indicate that skeletal muscle mitochondrial respiratory capacity of ‘lifelong trained’ older males is retained at a level comparable to young athletic individuals, and suggest that decrements in aerobic performance with age are primarily attributed to diminished cardiovascular function.ttributed to diminished cardiovascular function.)
Rufini 2012 Genes Dev + (Aging is associated with impaired scavengi … Aging is associated with impaired scavenging of reactive oxygen species (ROS). Here, we show that TAp73, a p53 family member, protects against aging by regulating mitochondrial activity and preventing ROS accumulation. TAp73-null mice show more pronounced aging with increased oxidative damage and senescence. TAp73 deletion reduces cellular ATP levels, oxygen consumption, and mitochondrial complex IV activity, with increased ROS production and oxidative stress sensitivity. We show that the mitochondrial complex IV subunit cytochrome C oxidase subunit 4 (Cox4i1) is a direct TAp73 target and that Cox4i1 knockdown phenocopies the cellular senescence of TAp73-null cells. Results indicate that TAp73 affects mitochondrial respiration and ROS homeostasis, thus regulating aging.nd ROS homeostasis, thus regulating aging.)
No 2020 Pflugers Arch + (Aging is associated with vulnerability to … Aging is associated with vulnerability to cardiovascular diseases, and mitochondrial dysfunction plays a critical role in cardiovascular disease pathogenesis. Exercise training is associated with benefits against chronic cardiac diseases. The purpose of this study was to determine the effects of aging and treadmill exercise training on mitochondrial function and apoptosis in the rat heart. Fischer 344 rats were divided into young sedentary (YS; ''N'' = 10, 4 months), young exercise (YE; n''N''= 10, 4 months), old sedentary (OS; ''N'' = 10, 20 months), and old exercise (OE; ''N'' = 10, 20 months) groups. Exercise training groups ran on a treadmill at 15 m/min (young) or 10 m/min (old), 45 min/day, 5 days/week for 8 weeks. Morphological parameters, mitochondrial function, mitochondrial dynamics, mitophagy, and mitochondria-mediated apoptosis were analyzed in cardiac muscle. Mitochondrial O2 respiratory capacity and Ca2+ retention capacity gradually decreased, and mitochondrial H2O2 emitting potential significantly increased with aging. Exercise training attenuated aging-induced mitochondrial H2O2 emitting potential and mitochondrial O2 respiratory capacity, while protecting Ca2+ retention in the old groups. Aging triggered imbalanced mitochondrial dynamics and excess mitophagy, while exercise training ameliorated the aging-induced imbalance in mitochondrial dynamics and excess mitophagy. Aging induced increase in Bax and cleaved caspase-3 protein levels, while decreasing Bcl-2 levels. Exercise training protected against the elevation of apoptotic signaling markers by decreasing Bax and cleaved caspase-3 and increasing Bcl-2 protein levels, while decreasing the Bax/Bcl-2 ratio and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive myonuclei. These data demonstrate that regular exercise training prevents aging-induced impairment of mitochondrial function and mitochondria-mediated apoptosis in cardiac muscles.ular exercise training prevents aging-induced impairment of mitochondrial function and mitochondria-mediated apoptosis in cardiac muscles.)
Daum 2013 Proc Natl Acad Sci U S A + (Aging is one of the most fundamental, yet … Aging is one of the most fundamental, yet least understood biological processes that affect all forms of eukaryotic life. Mitochondria are intimately involved in aging, but the underlying molecular mechanisms are largely unknown. Electron cryotomography of whole mitochondria from the aging model organism ''Podospora anserina'' revealed profound age-dependent changes in membrane architecture. With increasing age, the typical cristae disappear and the inner membrane vesiculates. The ATP synthase dimers that form rows at the cristae tips dissociate into monomers in inner-membrane vesicles, and the membrane curvature at the ATP synthase inverts. Dissociation of the ATP synthase dimer may involve the peptidyl prolyl isomerase cyclophilin D. Finally, the outer membrane ruptures near large contact-site complexes, releasing apoptogens into the cytoplasm. Inner-membrane vesiculation and dissociation of ATP synthase dimers would impair the ability of mitochondria to supply the cell with sufficient ATP to maintain essential cellular functions. to maintain essential cellular functions.)
Tyrrell 2019 Circ Res + (Aging is one of the strongest risk factors … Aging is one of the strongest risk factors for atherosclerosis. Yet whether aging increases the risk of atherosclerosis independently of chronic hyperlipidemia is not known. The objective was to determine if vascular aging prior to the induction of hyperlipidemia enhances atherogenesis. We analyzed the aortas of young and aged normolipidemic wild type (WT), disease free mice and found that aging led to elevated IL-6 levels and mitochondrial dysfunction, associated with increased mitophagy and the associated protein Parkin. In aortic tissue culture, we found evidence that with aging mitochondrial dysfunction and IL-6 exist in a positive feedback loop. We triggered acute hyperlipidemia in aged and young mice by inducing liver-specific degradation of the LDL receptor combined with a 10-week western diet and found that atherogenesis was enhanced in aged WT mice. Hyperlipidemia further reduced mitochondrial function and increased the levels of Parkin in the aortas of aged mice but not young mice. Genetic disruption of autophagy in smooth muscle cells of young mice exposed to hyperlipidemia led to increased aortic Parkin and IL-6 levels, impaired mitochondrial function, and enhanced atherogenesis. Importantly, enhancing mitophagy in aged, hyperlipidemic mice via oral administration of spermidine prevented the increase in aortic IL-6 and Parkin, attenuated mitochondrial dysfunction, and reduced atherogenesis.Prior to hyperlipidemia, aging elevates IL-6 and impairs mitochondrial function within the aorta, associated with enhanced mitophagy and increased Parkin levels. These age-associated changes prime the vasculature to exacerbate atherogenesis upon acute hyperlipidemia. Our work implies that novel therapeutics aimed at improving vascular mitochondrial bioenergetics or reducing inflammation before hyperlipidemia may reduce age-related atherosclerosis.ia may reduce age-related atherosclerosis.)
Shields 2021 Front Cell Dev Biol + (Aging is the greatest risk factor for a mu … Aging is the greatest risk factor for a multitude of diseases including cardiovascular disease, neurodegeneration and cancer. Despite decades of research dedicated to understanding aging, the mechanisms underlying the aging process remain incompletely understood. The widely-accepted free radical theory of aging (FRTA) proposes that the accumulation of oxidative damage caused by reactive oxygen species (ROS) is one of the primary causes of aging. To define the relationship between ROS and aging, there have been two main approaches: comparative studies that measure outcomes related to ROS across species with different lifespans, and experimental studies that modulate ROS levels within a single species using either a genetic or pharmacologic approach. Comparative studies have shown that levels of ROS and oxidative damage are inversely correlated with lifespan. While these studies in general support the FRTA, this type of experiment can only demonstrate correlation, not causation. Experimental studies involving the manipulation of ROS levels in model organisms have generally shown that interventions that increase ROS tend to decrease lifespan, while interventions that decrease ROS tend to increase lifespan. However, there are also multiple examples in which the opposite is observed: increasing ROS levels results in extended longevity, and decreasing ROS levels results in shortened lifespan. While these studies contradict the predictions of the FRTA, these experiments have been performed in a very limited number of species, all of which have a relatively short lifespan. Overall, the data suggest that the relationship between ROS and lifespan is complex, and that ROS can have both beneficial or detrimental effects on longevity depending on the species and conditions. Accordingly, the relationship between ROS and aging is difficult to generalize across the tree of life.ult to generalize across the tree of life.)
Dawson 2020 Exp Gerontol + (Aging is typically associated with a decli … Aging is typically associated with a decline in whole animal performance that ultimately contributes to death. It is suspected that a decline in ATP production leads to dysfunction in cellular processes, contributing to the decline in performance. Birds require large amounts of ATP to support physiological process, especially flight, which is one of the most energetically expensive forms of locomotion in the animal kingdom to sustain. Since the bulk of ATP production is coordinated through mitochondrial activity, we set out to explore mitochondrial function in young (~8 months) and old (~73 months) zebra finches (''Taeniopygia guttata''). We exploited the fact that avian red blood cells (RBCs) are nucleated and have functional mitochondria to explore the phenomenon of age-related decline in mitochondrial function without the need for terminal sampling. We found that RBCs from old zebra finches have lower flux control ratios (mitochondrial O2 consumption attributed to ATP production; 0.29-0.36-fold), exhibit higher respiration (1.4-fold), and significantly higher citrate synthase activity (1.4-fold) than young birds. Respiration rates normalized to citrate synthase activity suggest that mitochondrial quality is changing, as leak state is significantly lower (0.39-fold) in old zebra finches in comparison to young animals. Overall, our findings indicate a possible change in the function of mitochondria in older zebra finches, which may be associated with a corresponding increase in mitochondrial quantity, possibly to offset a decline in mitochondrial quality.Copyright © 2018. Published by Elsevier Inc.mall>Copyright © 2018. Published by Elsevier Inc.)
Pharaoh 2023 Geroscience + (Aging muscle experiences functional declin … Aging muscle experiences functional decline in part mediated by impaired mitochondrial ADP sensitivity. Elamipretide (ELAM) rapidly improves physiological and mitochondrial function in aging and binds directly to the mitochondrial ADP transporter ANT. We hypothesized that ELAM improves ADP sensitivity in aging leading to rescued physiological function. We measured the response to ADP stimulation in young and old muscle mitochondria with ELAM treatment, ''in vivo'' heart and muscle function, and compared protein abundance, phosphorylation, and S-glutathionylation of ADP/ATP pathway proteins. ELAM treatment increased ADP sensitivity in old muscle mitochondria by increasing uptake of ADP through the ANT and rescued muscle force and heart systolic function. Protein abundance in the ADP/ATP transport and synthesis pathway was unchanged, but ELAM treatment decreased protein s-glutathionylation incuding of ANT. Mitochondrial ADP sensitivity is rapidly modifiable. This research supports the hypothesis that ELAM improves ANT function in aging and links mitochondrial ADP sensitivity to physiological function. ELAM binds directly to ANT and ATP synthase and ELAM treatment improves ADP sensitivity, increases ATP production, and improves physiological function in old muscles.ves physiological function in old muscles.)
Bernhardt 2015 Sci Rep + (Aging of biological systems is accompanied … Aging of biological systems is accompanied by degeneration of mitochondrial functions. Different pathways are active to counteract the processes which lead to mitochondrial dysfunction. Mitochondrial dynamics, the fission and fusion of mitochondria, is one of these quality control pathways. Mitophagy, the controlled degradation of mitochondria, is another one. Here we show that these pathways are linked. A double deletion mutant of Saccharomyces cerevisiae in which two essential components of the fission and fusion machinery, Dnm1 and Mgm1, are simultaneously ablated, contain wild-type like filamentous mitochondria, but are characterized by impaired respiration, an increased sensitivity to different stressors, increased mitochondrial protein carbonylation, and a decrease in mitophagy and replicative lifespan. These data show that a balanced mitochondrial dynamics and not a filamentous mitochondrial morphotype per se is the key for a long lifespan and demonstrate a cross-talk between two different mitochondrial quality control pathways.nt mitochondrial quality control pathways.)
Hepple 2014 Abstract MiP2014 + (Aging of skeletal muscle is associated wit … Aging of skeletal muscle is associated with progressive atrophy, reaching clinically relevant thresholds in terms of weakness, mobility impairment and physical frailty in a significant fraction of individuals ≥80 y of age. Amongst the factors posited to be involved, mitochondrial alterations are implicated in the atrophy of aging muscle through recruitment of mitochondrial-mediated pathways of apoptosis and proteolysis. However, denervation is also known to recruit these same mitochondrial pathways. In view of the sporadic denervation that occurs in aging muscle, consideration of denervation’s role in recruitment of mitochondrial atrophy pathways is essential to identify relevant therapeutic targets. As such, this presentation will review our current evidence from human skeletal muscle biopsies across a range of ages and physical activity levels, examining the impact of aging on mitochondrial function and the role played by denervation across this continuum. As will be demonstrated, skeletal muscle mitochondrial alterations in septuagenarian subjects appears to be a primary event unrelated to denervation, where an increased susceptibility to mitochondrial permeability transition persists even in physically active subjects. In contrast, octogenarian subjects exhibit denervation-induced modulation of mitochondrial reactive oxygen species emission, suggesting failed reinnervation rather than mitochondrial dysfunction as a more appropriate therapeutic target when aging muscle atrophy becomes most clinically relevant. atrophy becomes most clinically relevant.)
Soares 2022 Geroscience + (Aging of the vasculature is characterized … Aging of the vasculature is characterized by endothelial dysfunction and arterial stiffening, two key events in the pathogenesis of cardiovascular disease (CVD). Treatment with sodium glucose transporter 2 (SGLT2) inhibitors is now known to decrease cardiovascular morbidity and mortality in type 2 diabetes. However, whether SGLT2 inhibition attenuates vascular aging is unknown. We first confirmed in a cohort of adult subjects that aging is associated with impaired endothelial function and increased arterial stiffness and that these two variables are inversely correlated. Next, we investigated whether SGLT2 inhibition with empagliflozin (Empa) ameliorates endothelial dysfunction and reduces arterial stiffness in aged mice with confirmed vascular dysfunction. Specifically, we assessed mesenteric artery endothelial function and stiffness (via flow-mediated dilation and pressure myography mechanical responses, respectively) and aortic stiffness (''in vivo'' via pulse wave velocity and ''ex vivo'' via atomic force microscopy) in Empa-treated (14 mg/kg/day for 6 weeks) and control 80-week-old C57BL/6 J male mice. We report that Empa-treated mice exhibited improved mesenteric endothelial function compared with control, in parallel with reduced mesenteric artery and aortic stiffness. Additionally, Empa-treated mice had greater vascular endothelial nitric oxide synthase activation, lower phosphorylated cofilin, and filamentous actin content, with downregulation of pathways involved in production of reactive oxygen species. Our findings demonstrate that Empa improves endothelial function and reduces arterial stiffness in a preclinical model of aging, making SGLT2 inhibition a potential therapeutic alternative to reduce the progression of CVD in older individuals.e progression of CVD in older individuals.)
Hagl 2016 Nutr Neurosci + (Aging represents a major risk factor for n … Aging represents a major risk factor for neurodegenerative diseases such as Alzheimer's disease. Mitochondria are significantly involved in both the aging process and neurodegeneration. One strategy to protect the brain and to prevent neurodegeneration is a healthy lifestyle including a diet rich in antioxidants and polyphenols. Rice bran extract (RBE) contains various antioxidants including natural vitamin E forms (tocopherols and tocotrienols) and gamma-oryzanol. In this work, we examined the effects of a stabilized RBE on mitochondrial function in 18-month-old Naval Medical Research Institute mice (340 mg/kg body weight/day), which received the extract for 3 weeks via oral gavage.Mitochondrial parameters were measured using high-resolution respirometry (Oroboros Oxygraph-2k), Western blot analysis, and photometric methods in dissociated brain cells, isolated mitochondria, and brain homogenate. Vitamin E concentrations in blood plasma and brain tissue were measured using HPLC with fluorescence detection. Aging leads to decreased mitochondrial function (decreased mitochondrial respiration and ATP production) and decreased protein expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1alpha). RBE administration increased alpha-tocopherol concentrations in the brain and compensated for age-related mitochondrial dysfunction by increasing mitochondrial respiration, membrane potential, PGC1alpha protein expression, and citrate synthase activity. Furthermore, resistance of brain cells to sodium nitroprusside-induced nitrosative stress was improved. According to these results, RBE is a promising candidate nutraceutical for the prevention of age-related neurodegenerative diseases.of age-related neurodegenerative diseases.)
Hagl 2016 Neuromolecular Med + (Aging represents a major risk factor for t … Aging represents a major risk factor for the development of neurodegenerative diseases like Alzheimer's disease (AD). As mitochondrial dysfunction plays an important role in brain aging and occurs early in the development of AD, the prevention of mitochondrial dysfunction might help to slow brain aging and the development of neurodegenerative diseases. Rice bran extract (RBE) contains high concentrations of vitamin E congeners and γ-oryzanol. We have previously shown that RBE increased mitochondrial function and protected from mitochondrial dysfunction ''in vitro'' and in short-term ''in vivo'' feeding studies. To mimic the use of RBE as food additive, we have now investigated the effects of a long-term (6 months) feeding of RBE on survival, behavior and brain mitochondrial function in aged NMRI mice. RBE administration significantly increased survival and performance of aged NMRI mice in the passive avoidance and Y-maze test. Brain mitochondrial dysfunction found in aged mice was ameliorated after RBE administration. Furthermore, data from mRNA and protein expression studies revealed an up-regulation of mitochondrial proteins in RBE-fed mice, suggesting an increase in mitochondrial content which is mediated by a peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α)-dependent mechanism. Our findings suggest that a long-term treatment with a nutraceutical containing RBE could be useful for slowing down brain aging and thereby delaying or even preventing AD.nd thereby delaying or even preventing AD.)
Reutzel 2018 Oxid Med Cell Longev + (Aging represents a major risk factor for d … Aging represents a major risk factor for developing neurodegenerative diseases such as Alzheimer's disease (AD). As components of the Mediterranean diet, olive polyphenols may play a crucial role in the prevention of AD. Since mitochondrial dysfunction acts as a final pathway in both brain aging and AD, respectively, the effects of a mixture of highly purified olive secoiridoids were tested on cognition and ATP levels in a commonly used mouse model for brain aging. Over 6 months, female NMRI mice (12 months of age) were fed with a blend containing highly purified olive secoiridoids (POS) including oleuropein, hydroxytyrosol and oleurosid standardized for 50 mg oleuropein/kg diet (equivalent to 13.75 mg POS/kg b.w.) or the study diet without POS as control. Mice aged 3 months served as young controls. Behavioral tests showed deficits in cognition in aged mice. Levels of ATP and mRNA levels of NADH-reductase, cytochrome-c-oxidase, and citrate synthase were significantly reduced in the brains of aged mice indicating mitochondrial dysfunction. Moreover, gene expression of Sirt1, CREB, Gap43, and GPx-1 was significantly reduced in the brain tissue of aged mice. POS-fed mice showed improved spatial working memory. Furthermore, POS restored brain ATP levels in aged mice which were significantly increased. Our results show that a diet rich in purified olive polyphenols has positive long-term effects on cognition and energy metabolism in the brain of aged mice.ergy metabolism in the brain of aged mice.)
Lee 2010 Cell Metab + (Aging-associated muscle insulin resistance … Aging-associated muscle insulin resistance has been hypothesized to be due to decreased mitochondrial function, secondary to cumulative free radical damage, leading to increased intramyocellular lipid content. To directly test this hypothesis, we examined both ''in vivo'' and ''in vitro'' mitochondrial function, intramyocellular lipid content, and insulin action in lean healthy mice with targeted overexpression of the human catalase gene to mitochondria (MCAT mice). Here, we show that MCAT mice are protected from age-induced decrease in muscle mitochondrial function (∼30%), energy metabolism (∼7%), and lipid-induced muscle insulin resistance. This protection from age-induced reduction in mitochondrial function was associated with reduced mitochondrial oxidative damage, preserved mitochondrial respiration and muscle ATP synthesis, and AMP-activated protein kinase-induced mitochondrial biogenesis. Taken together, these data suggest that the preserved mitochondrial function maintained by reducing mitochondrial oxidative damage may prevent age-associated whole-body energy imbalance and muscle insulin resistance.y imbalance and muscle insulin resistance.)
Cockova 2017 Thesis + (Aim of this thesis was to observe changes … Aim of this thesis was to observe changes in oxidative metabolism and expression of important neuroenergetic proteins in human neuroblastoma cell line SH-SY5Y due to inhibition of FTO. FTO is a RNA demethylase that uses N6-methyladenosine as substrate. Differences in enzyme expression are connected to a broad area of effects involving energy homeostasis.Mitochondria are the cellular powerhouses, a key elements in production of energy and metabolic substrates, yet a source of potentially dangerous reactive oxygen species (ROS) and analogous reactive molecules. In order to better understand FTO purpose in neuronal energetic metabolism, we examined mitochondrial respiratory chain. Using high-resolution respirometry we were capable of observing impairment in mitochondrial respiration after FTO inhibition. There was a considerable decline in endogenous respiration, maximal respiration rate and reserve capacity. In order to obtain a more detailed view into mitochondrial respiration, expression levels of electron-transport complexes were quantified by Western blot technique. A slight reduction was identified in subunits of complex I and IV. However, the most prominent alteration was seen in the complex II subunit. There were no differences in expression of complex III and ATP synthase subunits. Beside disrupted activity of electron-transport system, ROS production can reflect mitochondrial dysfunction. By using fluorescence probes, we managed to observe increased ROS production in cells treated with FTO inhibitor.Furthermore, we studied how FTO inhibition affects insulin signaling. Expression of selected proteins involved in insulin signaling was detected by Western blot. Increased levels of insulin receptor and insulin degrading enzyme accompanied FTO inhibition. Additionally, a decreased ratio of p-Akt/Akt and p-p38/p38 together with an elevated ratio of p-ERK/ERK was observed. A minimal difference was sighted in PI3K p110 expression or p-GSK3β/GSK3β ratio.Taken together, these results suggest a considerable link between FTO activity and neuronal signaling and metabolic actions. Further research could undoubtedly prove to be beneficial in gaining knowledge about bioenergetics processes in the nervous system.nergetics processes in the nervous system.)
Larsen 2009 Diabetologia + (Aim/hypothesis: The aim of the study was t … Aim/hypothesis: The aim of the study was to investigate mitochondrial function, fibre type distribution and substrate oxidation in arm and leg muscle during exercise in patients with type 2 diabetes and in obese and lean controls.Methods: Indirect calorimetry was used to calculate fat and carbohydrate oxidation during both progressive arm-cranking and leg-cycling exercises. Muscle biopsies from arm and leg were obtained. Fibre type, as well as O2 flux capacity of saponin-permeabilised muscle fibres were measured, the latter by high resolution respirometry, in patients with type 2 diabetes, age- and BMI-matched obese controls, and age-matched lean controls.Results: Fat oxidation was similar in the groups during either arm or leg exercise. During leg exercise at higher intensities, but not during arm exercise, carbohydrate oxidation was lower in patients with type 2 diabetes compared with the other groups. In patients with type 2 diabetes, ADP-stimulated state 3 respiration per mg muscle with parallel electron input from complex I+II was lower in ''m. vastus lateralis'' compared with obese and lean controls, whereas no differences between groups were present in ''m. deltoideus''. A higher percentage of type IIX fibres was seen in ''m. vastus lateralis'' in patients with type 2 diabetes compared with obese and lean controls, whereas no difference was found in the deltoid muscle.Conclusions/interpretation: This study demonstrates similar O2 flux capacity, fibre type distribution and carbohydrate oxidation in arm muscle in the groups despite the presence of attenuated values in leg muscle in patients with type 2 diabetes compared with obese and lean controls.tients with type 2 diabetes compared with obese and lean controls.)
Raboel 2009 J Clin Endocrinol Metabol + (Aim: Skeletal muscle mitochondrial content … Aim: Skeletal muscle mitochondrial content is reduced in type 2 diabetes mellitus (T2DM). Whether hyperglycemia inhibits mitochondrial biogenesis and/or function is unknown. This study examined the effect of different levels of glycemia on skeletal muscle mitochondrial function in patients with T2DM.Patients and Methods: Eleven patients with T2DM [9 males, 2 females; age, 52.8 ± 2.5 yr (mean ± SE); body mass index, 30.2 ± 1.1 kg/m2 ] in poor glycemic control were treated with insulin aspart and NPH insulin for a median period of 46 d (range, 31–59). Mitochondrial respiration and citrate synthase activity (a marker of mitochondrial content) were measured before and after treatment. Eleven healthy subjects (age, 53.3 ± 2.7 yr; body mass index, 30.6 ± 1.1 kg/m2) were included as controls.Results: Hemoglobin A1c (9.1 ± 0.5 to 7.5 ± 0.3%; P < 0.001) and fasting plasma glucose (12.7 ± 1.1 to 6.5 ± 0.3 mmol/liter; P < 0.001) were reduced after treatment. Mitochondrial respiration per milligram muscle was lower in T2DM compared to controls [substrates for complex I, 24% lower (P < 0.05); substrates for complex I+II, 17% lower (P < 0.05)]. Mitochondrial respiration and citrate synthase activity did not differ before and after improvements in glycemic control, but mitochondrial respiration correlated with fasting plasma glucose before (r2 = 0.53; P < 0.05) but not after treatment [r2 = 0.0024; not significant (NS)]. Mitochondrial respiration normalized to mitochondrial content did not differ between control subjects and patients with T2DM.Discussion: Mitochondrial respiration and content was not improved after significant improvements in glycemic control. However, severe hyperglycemia inhibited respiration reversibly, but moderate hyperglycemia and mitochondrial function were not correlated.ration reversibly, but moderate hyperglycemia and mitochondrial function were not correlated.)
Baron 2010 Thesis + (Aim: The aim of this thesis was the analys … Aim: The aim of this thesis was the analysis of copy number variations of themitochondrial DNA (mtDNA) in several tissues and cell types with regard to different mitochondrial associated disorders.Background: The mtDNA copy number can be reduced due to mutations in thenuclear encoded DNA polymerase g (POLG) or damages caused by deleteriousreactive oxygen species (ROS), which are created by the respiratory chain. Thisleads to the insufficient expression of mitochondrial encoded subunits of complexes of the oxidative phosphorylation system (OXPHOS). Consequently an impairment of the biochemical activity and integrity of the cells occurs.Methods: The quantification of the mtDNA was performed by quantitative PCR(qPCR). Biochemical activities were determined by enzymatic assays such as direct measurement of the citrate synthase (CS) activity or comprehensive measurement of the respiratory activity.Results: Mutations in the nuclear inherited gene POLG result in mtDNA depletion in mitochondrial disorders including a mild phenotype of progressive externalophthalmoplegia (PEO) with epilepsy/ataxia. A mtDNA depletion was detected indifferent tissues and cell types of Alpers-Huttenlocher patients with pathogenicnuclear mutations. The mtDNA copy number was reduced in specific hippocampalregions of temporal lobe epilepsy (TLE) patients with Ammons’ horn sclerosis (AHS)accompanied by a decreased CS activity. An ''in vitro'' reduction of the mtDNA in fibroblasts results in an impaired respiratory activity.Conclusions: The mtDNA content is proportional to the mitochondria content andthe energy demand of the respective tissue or cell type under normal conditions. A cell type- and tissue-specific depletion of the mtDNA can be present in several inherited and somatic mitochondrial disorders ''in vivo'' or can be generated by an ''in vitro'' system. The mtDNA depletion diminishes the biochemical activity and integrity of the cells and can contribute to the disease phenotype.d can contribute to the disease phenotype.)
Lai 2019 Acta Physiol (Oxf) + (Aim: The subsarcolemmal (SSM) and interfib … Aim: The subsarcolemmal (SSM) and interfibrillar (IFM) mitochondria in skeletal muscle appear to have distinct biochemical properties affecting metabolism in health and disease. The isolation of mitochondrial subpopulations has been a long-time challenge while the presence of a continuous mitochondrial reticulum challenges the view of distinctive SSM and IFM bioenergetics. Here, a comprehensive approach is developed to identify the best conditions to separate mitochondrial fractions.Methods: The main modifications to the protocol to isolate SSM and IFM from rat skeletal muscle were: (a) decreased dispase content and homogenization speed; (b) trypsin treatment of SSM fractions; (c) recentrifugation of mitochondrial fractions at low speed to remove subcellular components. To identify the conditions preserving mitochondrial function, integrity, and maximizing their recovery, microscopy (light and electron) were used to monitor effectiveness and efficiency in separating mitochondrial subpopulations while respiratory and enzyme activities were employed to evaluate function, recovery, and integrity.Results: With the modifications described, the total mitochondrial yield increased with a recovery of 80% of mitochondria contained in the original skeletal muscle sample. The difference between SSM and IFM oxidative capacity (10%) with complex-I substrate was significant only with a saturated ADP concentration. The inner and outer membrane damage for both subpopulations was <1% and 8%, respectively, while the respiratory control ratio was 16.Conclusion: Using a multidisciplinary approach, conditions were identified to maximize SSM and IFM recovery while preserving mitochondrial integrity, biochemistry, and morphology. High quality and recovery of mitochondrial subpopulations allow to study the relationship between these organelles and disease.ionship between these organelles and disease.)
Hedges IBEC2012 + (Aim: This study aimed to compare mitochond … Aim: This study aimed to compare mitochondrial oxygen consumption in C57BL/6J wild-type and myostatin-deficient mouse soleus and white gastrocnemius muscles.Methods: Muscles were obtained from 4 month-old male mice. Mass-specific oxygen consumption (pmol.O2/mg/sec) was measured in permeabilised muscle, using high-resolution respirometry (Oroboros Oxygraph-2k). Maximal activities of citrate synthase and lactate dehydrogenase were determined by spectrophotometry.Results: Myostatin-deficient soleus (n=6) consumed 20% more oxygen per mg than wild-type soleus (n=6) during oxidative phosphorylation. This was accompanied by greater citrate synthase and lactate dehydrogenase enzyme activity in myostatin-deficient soleus (29% and 80% respectively). Myostatin-deficient gastrocnemius (n=7) showed 26% lower oxygen consumption during uncoupled respiration, and 34% lower oxygen consumption when oxidising glycerol-3-phosphate compared to wild-type gastrocnemius (n=8). Citrate synthase activity was not significantly different and lactate dehydrogenase activity 26% greater in myostatin-deficient gastrocnemius compared to wild-type gastrocnemius.Conclusion: These data suggest that myostatin-deficiency exerts fiber-type specific effects on skeletal muscle mitochondrial function.on skeletal muscle mitochondrial function.)
Chu SRS 2011 + (Aim: To determine the impact of cold ischa … Aim: To determine the impact of cold ischaemia on hepatic mitochondrial function in University of Wisconsin (UW) solution in the setting of hepatic steatosis.Methods: Livers were harvested from 10-week old genetically obese (ob/ob, ''n'' = 9) or lean C57 control mice (''n'' = 9); and preserved in ice-cold UW solution. Mitochondrial function analysis was performed on permeabilised liver samples using a substrate and inhibitor titration protocol in conjunction with a high-resolution respirometer (OROBOROS® Oxygraph-2k) at multiple time-points over 24 h during cold ischemia (CI).Results: Ob/ob mice livers and control mice livers showed either severe (> 60%) or no macrovesicular steatosis respectively. Mitochondria from ob/ob mice livers demonstrated a faster and greater decrease in the percentage of respiration contributing to oxidative phosphorylation over 24 hours of cold storage compared to control mice. After 12 hours of CI, there was also an increased dependence on Complex II respiration relative to Complex I in ob/ob mice livers suggestive of Complex I damage and potential loss of key ATP synthesis efficiency.Conclusion: There was a time-dependant damage of hepatic mitochondrial function during CI. Steatotic livers demonstrated greater mitochondrial dysfunction during CI compared to lean livers.ysfunction during CI compared to lean livers.)
Bakkman 2007 ActaPhysiol + (Aim: To investigate if training during hyp … Aim: To investigate if training during hypoxia (H) improves the adaptation of muscle oxidative function compared with normoxic (N) training performed at the same relative intensity.Method: Eight untrained volunteers performed one-legged cycle training during 4 weeks in a low-pressure chamber. One leg was trained under N conditions and the other leg under hypobaric hypoxia (526 mmHg) at the same relative intensity as during N (65% of maximal power output, ''W''max). Muscle biopsies were taken from vastus lateralis before and after the training period. Muscle samples were analysed for the activities of oxidative enzymes [citrate synthase (CS) and cytochrome c oxidase (COX)] and mitochondrial respiratory function.Results: ''W''max increased with more than 30% over the training period during both N and H. CS activity increased significantly after training during N conditions (+20.8%, P < 0.05) but remained unchanged after H training (+4.5%, ns) with a significant difference between conditions (''P'' < 0.05 H vs. N). COX activity was not significantly changed by training and was not different between exercise conditions [+14.6 (N) vs. -2.3% (H), ns]. Maximal ADP stimulated respiration (state 3) expressed per weight of muscle tended to increase after N (+31.2%, ''P'' < 0.08) but not after H training (+3.2%, ns). No changes were found in state four respiration, respiratory control index, P/O ratio, mitochondrial Ca2+ resistance and apparent ''K''m for oxygen.Conclusion: The training-induced increase in muscle oxidative function observed during N was abolished during H. Altitude training may thus be disadvantageous for adaptation of muscle oxidative function.ng may thus be disadvantageous for adaptation of muscle oxidative function.)
Cour 2014 J Cardiovasc Pharmacol Ther + (Aim: To investigate whether slight variati … Aim: To investigate whether slight variations in core temperature prior to cardiac arrest (CA) influence short-term outcomes and mitochondrial functions.Three groups of New Zealand White rabbits (n = 12/group) were submitted to 15 minutes of CA at 38°C (T-38 group), 39°C (T-39), or 40°C (T 40) and 120 minutes of reperfusion. A Sham-operated group (n = 6) underwent only surgery. Restoration of spontaneous circulation (ROSC), survival, hemodynamics, and pupillary reactivity were recorded. Animals surviving to the end of the observation period were euthanized to assess fresh brain and heart mitochondrial functions (permeability transition and oxidative phosphorylation). Markers of brain and heart damages were also measured.The duration of asphyxia required to induce CA was significantly lower in the T-40 group when compared to the T-38 group (''p''<.05). The rate of ROSC was >80% in all groups (''p''=nonsignificant [ns]). Survival significantly differed among the T-38, T-39, and T-40 groups: 10 (83%) of 12, 7 (58%) of 12, and 4 (33%) of 12, respectively (log-rank test, ''p''=.027). At the end of the protocol, none of the animals in the T-40 group had pupillary reflexes compared to 8 (67%) of 12 in the T-38 group (''p''<.05). Troponin and protein S100B were significantly higher in the T-40 versus T-38 group (''p''<.05). Cardiac arrest significantly impaired both inner mitochondrial membrane integrity and oxidative phosphorylation in all groups. Brain mitochondria disorders were significantly more severe in the T-40 group compared to the T-38 group (''p''< .05).Small changes in body temperature prior to asphyxial CA significantly influence brain mitochondrial functions and short-term outcomes in rabbits.tochondrial functions and short-term outcomes in rabbits.)
Orynbayeva 2015 Nanomedicine (Lond) + (Aim: To successfully translate magneticall … Aim: To successfully translate magnetically mediated cell targeting from bench to bedside, there is a need to systematically assess the potential adverse effects of magnetic nanoparticles (MNPs) interacting with ‘therapeutic’ cells. Here, we examined in detail the effects of internalized polymeric MNPs on primary rat endothelial cells’ structural intactness, metabolic integrity and proliferation potential.Materials & methods: The intactness of cytoskeleton and organelles was studied by fluorescentconfocal microscopy, flow cytometry and high-resolution respirometry. Results: MNPloaded primary endothelial cells preserve intact cytoskeleton and organelles, maintain normal rate of proliferation, calcium signaling and mitochondria energy metabolism.Conclusion: This study provides supportive evidence that MNPs at doses necessaryfor targeting did not induce significant adverse effects on structural integrity and functionality of primary endothelial cells – potential cell therapy vectors.helial cells – potential cell therapy vectors.)
Doerrier 2014 Life Sci + (Aims. Previous data showed that melatonin … Aims. Previous data showed that melatonin maintains liver mitochondrial homeostasis during sepsis, but neither the mechanisms underlying mitochondrial dysfunction nor the target of melatonin are known.Main methods. Here, we analyzed mitochondrial respiration in isolated mouse liver mitochondria with different substrate combinations (glutamate/malate, glutamate/malate/sucinate or succinate/rotenone) to identify mitochondrial defects and melatonin targets during sepsis. Other bioenergetic parameters including a + a3, b, and c + c1 content, mitochondrial mass, and mitochondrial supercomplexes formation were analyzed. Mitochondrial function was assessed during experimental sepsis induced by cecal ligation and puncture (CLP) in livers of 3 mo. C57BL/6 mice at early and late phases of sepsis, i.e., at 8 and 24 h after sepsis induction.Key findings. Septic mice showed mitochondrial injury with a decrease in state 3, respiratory control rate, mitochondrial mass, and cytochrome b and c + c1 content, which was prevented by melatonin treatment. Mitochondrial dysfunction in sepsis was mainly linked to complex I damage, because complex II was far less impaired. These mitochondria preserved the respiratory supramolecular organization, maintaining their electron transport system capacity.Significance. This work strengthens the use of substrate combinations to identify specific respiratory defects and selective melatonin actions in septic mitochondria. Targeting mitochondrial complex I should be a main therapeutical approach in the treatment of sepsis, whereas the use of melatonin should be considered in the therapy of clinical sepsis.sidered in the therapy of clinical sepsis.)
Boushel 2007 Diabetologia + (Aims/hypothesis: Insulin resistance and ty … Aims/hypothesis: Insulin resistance and type 2 diabetes are associated with mitochondrial dysfunction. The aim of the present study was to test the hypothesis that oxidative phosphorylation and electron transport capacity are diminished in the skeletal muscle of type 2 diabetic subjects, as a result of a reduction in the mitochondrial content.Materials and methods: The O2 flux capacity of permeabilised muscle fibres from biopsies of the quadriceps in healthy subjects (''n''=8; age 58±2 years [mean±SEM]; BMI 28±1 kg/m2; fasting plasma glucose 5.4±0.2 mmol/l) and patients with type 2 diabetes (''n''=11; age 62±2 years; BMI 32±2 kg/m2; fasting plasma glucose 9.0±0.8 mmol/l) was measured by high-resolution respirometry.Results: O2 flux expressed per mg of muscle (fresh weight) during ADP-stimulated state 3 respiration was lower ( ''p''<0.05) in patients with type 2 diabetes in the presence of complex I substrate (glutamate) (31±2 vs 43±3 pmol O2 s-1 mg-1) and in response to glutamate + succinate (parallel electron input from complexes I and II) (63±3 vs 85±6 pmol s-1 mg-1). Further increases in O2 flux capacity were observed in response to uncoupling by FCCP, but were again lower ( ''p''<0.05) in type 2 diabetic patients than in healthy control subjects (86±4 vs 109±8 pmol s-1 mg-1). However, when O2 flux was normalised for mitochondrial DNA content or citrate synthase activity,there were no differences in oxidative phosphorylation or electron transport capacity between patients with type 2 diabetes and healthy control subjects.Conclusions/interpretation: Mitochondrial function is normal in type 2 diabetes. Blunting of coupled and uncoupled respiration in type 2 diabetic patients can be attributed to lower mitochondrial content.Conclusions/interpretation: Mitochondrial function is normal in type 2 diabetes. Blunting of coupled and uncoupled respiration in type 2 diabetic patients can be attributed to lower mitochondrial content.)
Winnica 2019 Antioxid Redox Signal + (Aims: Asthma, characterized by airway obst … Aims: Asthma, characterized by airway obstruction and hyper-responsiveness, is more severe and less responsive to treatment in obese subjects. While alterations in mitochondrial function and redox signaling have been implicated in asthma pathogenesis, it is unclear whether these mechanisms differ in lean versus obese asthmatics. In addition, we previously demonstrated that circulating platelets from asthmatic individuals have altered bioenergetics; however, it is unknown whether platelet mitochondrial changes reflect those observed in airway epithelial cells. Herein we hypothesized that lean and obese asthmatics show differential bioenergetics and redox signaling in airway cells and that these alterations could be measured in platelets from the same individual. Results: Using freshly isolated bronchial airway epithelial cells and platelets from lean and obese asthmatics and healthy individuals, we show that both cell types from obese asthmatics have significantly increased glycolysis, basal and maximal respiration, and oxidative stress compared with lean asthmatics and healthy controls. This increased respiration was associated with enhanced arginine metabolism by arginase, which has previously been shown to drive respiration. Inducible nitric oxide synthase (iNOS) was also upregulated in cells from all asthmatics. However, due to nitric oxide synthase uncoupling in obese asthmatics, overall nitric oxide (NO) bioavailability was decreased, preventing NO-dependent inhibition in obese asthmatic cells that was observed in lean asthmatics. Innovation and Conclusion: These data demonstrate bioenergetic differences between lean and obese asthmatics that are, in part, due to differences in NO signaling. They also suggest that the platelet may serve as a useful surrogate to understand redox, oxidative stress and bioenergetic changes in the asthmatic airway.energetic changes in the asthmatic airway.)
Takada 2016 Cardiovasc Res + (Aims: Exercise capacity is reduced in hear … Aims: Exercise capacity is reduced in heart failure (HF) patients, due mostly to skeletal muscle abnormalities including impaired energy metabolism, mitochondrial dysfunction, fibre type transition, and atrophy. Glucagon-like peptide-1 (GLP-1) has been shown to improve exercise capacity in HF patients. We investigated the effects of the administration of a dipeptidyl peptidase (DPP)-4 inhibitor on the exercise capacity and skeletal muscle abnormalities in an HF mouse model after myocardial infarction (MI).Methods and results: MI was created in male C57BL/6J mice by ligating the left coronary artery, and a sham operation was performed in other mice. The mice were then divided into two groups according to the treatment with or without a DPP-4 inhibitor, MK-0626 [1 mg/kg body weight (BW)/day] provided in the diet. Four weeks later, the exercise capacity evaluated by treadmill test was revealed to be limited in the MI mice, and it was ameliorated in the MI + MK-0626 group without affecting the infarct size or cardiac function. The citrate synthase activity, mitochondrial oxidative phosphorylation capacity, supercomplex formation, and their quantity were reduced in the skeletal muscle from the MI mice, and these decreases were normalized in the MI + MK-0626 group, in association with the improvement of mitochondrial biogenesis. Immunohistochemical staining also revealed that a shift toward the fast-twitch fibre type in the MI mice was also reversed by MK-0626. Favourable effects of MK-0626 were significantly inhibited by treatment of GLP-1 antagonist, Exendin-(9-39) (150 pmol/kg BW/min, subcutaneous osmotic pumps) in MI + MK-0626 mice. Similarly, exercise capacity and mitochondrial function were significantly improved by treatment of GLP-1 agonist, Exendin-4 (1 nmol/kg/BW/h, subcutaneous osmotic pumps).Conclusions: A DPP-4 inhibitor may be a novel therapeutic agent against the exercise intolerance seen in HF patients by improving the mitochondrial biogenesis in their skeletal muscle.drial biogenesis in their skeletal muscle.)
Nambu 2021 Cardiovasc Res + (Aims: Exercise intolerance in patients wit … Aims: Exercise intolerance in patients with heart failure (HF) is partly attributed to skeletal muscle abnormalities. We have shown that reactive oxygen species (ROS) play a crucial role in skeletal muscle abnormalities, but the pathogenic mechanism remains unclear. Xanthine oxidase (XO) is reported to be an important mediator of ROS overproduction in ischaemic tissue. Here, we tested the hypothesis that skeletal muscle abnormalities in HF are initially caused by XO-derived ROS and are prevented by the inhibition of their production.Methods and results: Myocardial infarction (MI) was induced in male C57BL/6J mice, which eventually led to HF, and a sham operation was performed in control mice. The time course of XO-derived ROS production in mouse skeletal muscle post-MI was first analysed. XO-derived ROS production was significantly increased in MI mice from Days 1 to 3 post-surgery (acute phase), whereas it did not differ between the MI and sham groups from 7 to 28 days (chronic phase). Second, mice were divided into three groups: sham + vehicle (Sham + Veh), MI + vehicle (MI + Veh), and MI + febuxostat (an XO inhibitor, 5 mg/kg body weight/day; MI + Feb). Febuxostat or vehicle was administered at 1 and 24 h before surgery, and once-daily on Days 1-7 post-surgery. On Day 28 post-surgery, exercise capacity and mitochondrial respiration in skeletal muscle fibres were significantly decreased in MI + Veh compared with Sham + Veh mice. An increase in damaged mitochondria in MI + Veh compared with Sham + Veh mice was also observed. The wet weight and cross-sectional area of slow muscle fibres (higher XO-derived ROS) was reduced via the down-regulation of protein synthesis-associated mTOR-p70S6K signalling in MI + Veh compared with Sham + Veh mice. These impairments were ameliorated in MI + Feb mice, in association with a reduction of XO-derived ROS production, without affecting cardiac function.Conclusion: XO inhibition during the acute phase post-MI can prevent skeletal muscle abnormalities and exercise intolerance in mice with HF. and exercise intolerance in mice with HF.)
Doridot 2014 Antioxid Redox Signal + (Aims: Storkhead Box 1 (STOX1) is a winged- … Aims: Storkhead Box 1 (STOX1) is a winged-helix transcription factor implicated in the genetic forms of a high-prevalence human gestational disease, preeclampsia. STOX1 overexpression confers preeclampsia-like transcriptomic features to trophoblastic cell lines, and preeclampsia symptoms to pregnant mice. The aim of this work was to evaluate the impact of STOX1 on free radical equilibrium and mitochondrial function, ''in vitro'' and ''in vivo''. Results: Transcriptome analysis of STOX1-transgenic versus non-transgenic placentas at 16.5 days of gestation revealed alterations of mitochondria-related pathways. Placentas overexpressing STOX1 displayed altered mitochondrial mass and were severely biased towards protein nitration, indicating nitroso-redox imbalance ''in vivo''. Trophoblast cells overexpressing STOX1 displayed an increased mitochondrial activity at 20% O2 and in hypoxia, despite a reduction of the mitochondrial mass in this situation. STOX1 overexpression is therefore associated to hyperactive mitochondria leading to increased free radical production. Moreover, nitric oxide (NO) production pathways were activated, resulting in peroxynitrite formation. At low oxygen pressure, STOX1 overexpression in the placenta as well as in a trophoblast cell line, switched the free radical balance from Reactive Oxygen Species (ROS) to Reactive Nitrogen Species (RNS). Innovation: In preeclamptic placentas, NO interacts with ROS to generate peroxynitrite and nitrated proteins as end products. This process will deprive the maternal organism of NO, a crucial vasodilator molecule. Conclusion: Our data posit STOX1 as a genetic switch in the ROS/RNS balance and suggest an explanation for elevated blood pressure in preeclampsia.r elevated blood pressure in preeclampsia.)
Hu 2024 Ecotoxicol Environ Saf + (Airborne fine particulate matter (PM<su … Airborne fine particulate matter (PM2.5) exposure is closely associated with metabolic disturbance, in which brown adipose tissue (BAT) is one of the main contributing organs. However, knowledge of the phenotype and mechanism of PM2.5 exposure-impaired BAT is quite limited. In the study, male C57BL/6 mice at three different life phases (young, adult, and middle-aged) were simultaneously exposed to concentrated ambient PM2.5 or filtered air for 8 weeks using a whole-body inhalational exposure system. H&E staining and high-resolution respirometry were used to assess the size of adipocytes and mitochondrial function. Transcriptomics was performed to determine the differentially expressed genes in BAT. Quantitative RT-PCR, immunohistochemistry staining, and immunoblots were performed to verify the transcriptomics and explore the mechanism for BAT mitochondrial dysfunction. Firstly, PM2.5 exposure caused altered BAT morphology and mitochondrial dysfunction in middle-aged but not young or adult mice. Furthermore, PM2.5 exposure increased cellular senescence in BAT of middle-aged mice, accompanied by cell cycle arrest, impaired DNA replication, and inhibited AKT signaling pathway. Moreover, PM2.5 exposure disrupted apoptosis and autophagy homeostasis in BAT of middle-aged mice. Therefore, BAT in middle-aged mice was more vulnerable to PM2.5 exposure, and the cellular senescence-initiated apoptosis, autophagy, and mitochondrial dysfunction may be the mechanism of PM2.5 exposure-induced BAT impairment.ated apoptosis, autophagy, and mitochondrial dysfunction may be the mechanism of PM2.5 exposure-induced BAT impairment.)
Goo 2012 PLoS One + (Akt, a serine/threonine kinase has been sh … Akt, a serine/threonine kinase has been shown to stimulate glycolysis in cancer cells but its role in mitochondrial respiration is unknown. Using PTEN-knockout mouse embryonic fibroblasts (MEF(PTEN-/-)) with hyper-activated Akt as a cell model, we observed a higher respiratory capacity in MEF(PTEN-/-) compared to the wildtype (MEF(WT)). The respiratory phenotype observed in MEF(PTEN-/-) was reproduced in MEF(WT) by gene silencing of PTEN which substantiated its role in regulating mitochondrial function. The increased activities of the respiratory complexes (RCs) I, III and IV were retained in the same relative proportions as those present in MEF(WT), alluding to a possible co-ordinated regulation by PTEN/Akt. Using LY294002 (a PI3K inhibitor) and Akt inhibitor IV, we showed that the regulation of enzyme activities and protein expressions of the RCs was dependent on PI3K/Akt. There was insignificant difference in the protein expressions of mitochondrial transcription factor: peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and its downstream targets, the nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (mtTFA) between MEF(PTEN-/-) and MEF(WT). Similarly, mRNA levels of the same subunits of the RCs detected in Western blots were not significantly different between MEF(PTEN-/-) and MEF(WT) suggesting that the regulation by Akt on mitochondrial function was probably not via gene transcription. On the other hand, a decrease of total 4E-BP1 with a higher expression of its phosphorylated form relative to total 4E-BP1 was found in MEF(PTEN-/-), which inferred that the regulation of mitochondrial respiratory activities by Akt was in part through this protein translation pathway. Notably, gene silencing of 4E-BP1 up-regulated the protein expressions of all RCs and the action of 4E-BP1 appeared to be specific to these mitochondrial proteins. In conclusion, PTEN inactivation bestowed a bioenergetic advantage to the cells by up-regulating mitochondrial respiratory capacity through the 4E-BP1-mediated protein translation pathway.-BP1-mediated protein translation pathway.)
Jasz 2021 J Cell Mol Med + (Albeit previous experiments suggest potent … Albeit previous experiments suggest potential anti-inflammatory effect of exogenous methane (CH4) in various organs, the mechanism of its bioactivity is not entirely understood. We aimed to investigate the potential mitochondrial effects and the underlying mechanisms of CH4 in rat cardiomyocytes and mitochondria under simulated ischaemia/reperfusion (sI/R) conditions. Three-day-old cultured cardiomyocytes were treated with 2.2% CH4 -artificial air mixture during 2-hour-long reoxygenation following 4-hour-long anoxia (sI/R and sI/R + CH4 , n = 6-6), with normoxic groups serving as controls (SH and SH + CH4 ; n = 6-6). Mitochondrial functions were investigated with high-resolution respirometry, and mitochondrial membrane injury was detected by cytochrome c release and apoptotic characteristics by using TUNEL staining. CH4 admixture had no effect on complex II (CII)-linked respiration under normoxia but significantly decreased the complex I (CI)-linked oxygen consumption. Nevertheless, addition of CH4 in the sI/R + CH4 group significantly reduced the respiratory activity of CII in contrast to CI and the CH4 treatment diminished mitochondrial H2O2 production. Substrate-induced changes to membrane potential were partially preserved by CH4 , and additionally, cytochrome c release and apoptosis of cardiomyocytes were reduced in the CH4 -treated group. In conclusion, the addition of CH4 decreases mitochondrial ROS generation via blockade of electron transport at CI and reduces anoxia-reoxygenation-induced mitochondrial dysfunction and cardiomyocyte injury ''in vitro''.4 decreases mitochondrial ROS generation via blockade of electron transport at CI and reduces anoxia-reoxygenation-induced mitochondrial dysfunction and cardiomyocyte injury ''in vitro''.)
Karadayian 2015 Neuroscience + (Alcohol hangover (AH) is defined as the te … Alcohol hangover (AH) is defined as the temporary state after alcohol binge-like drinking, starting when ethanol (EtOH) is absent in plasma. Previous data indicate that AH induces mitochondrial dysfunction and free radical production in mouse brain cortex. The aim of this work was to study mitochondrial function and reactive oxygen species production in mouse cerebellum at the onset of AH. Male mice received a single i.p. injection of EtOH (3.8g/kg BW) or saline solution. Mitochondrial function was evaluated 6h after injection (AH onset). At the onset of AH, malate-glutamate and succinate-supported state 4 oxygen uptake was 2.3 and 1.9-fold increased leading to a reduction in respiratory control of 55% and 48% respectively, as compared with controls. Decreases of 38% and 16% were found in Complex I-III and IV activities. Complex II-III activity was not affected by AH. Mitochondrial membrane potential and mitochondrial permeability changes were evaluated by flow cytometry. Mitochondrial membrane potential and permeability were decreased by AH in cerebellum mitochondria. Together with this, AH induced a 25% increase in superoxide anion and a 92% increase in hydrogen peroxide production in cerebellum mitochondria. Related to nitric oxide (NO) metabolism, neuronal nitric oxide synthase (nNOS) protein expression was 52% decreased by the hangover condition compared with control group. No differences were found in cerebellum NO production between control and treated mice. The present work demonstrates that the physiopathological state of AH involves mitochondrial dysfunction in mouse cerebellum showing the long-lasting effects of acute EtOH exposure in the central nervous system.OH exposure in the central nervous system.)
Wang 2009 Int J Clin Exp Pathol + (Alcohol use has become far too prevalent i … Alcohol use has become far too prevalent in our society. Alcohol kills 6.5 times more youth than all other illicit drugs combined. In combination with traumatic and hemorrhagic injuries, alcohol results in a much higher mortality rate. Alcohol, alone and in high dosages, also causes great damage to the body, often leading to death as well. Thus, it is of utmost importance that research is conducted to help explain the pathological mechanism of high fatalities and injuries associated with alcohol use. In order to simulate this complex situation in vitro, a rat hepatoma cell line (H-II-4-E) was exposed to various concentrations of ethanol as well as the condition of hypoxia. Hypoxia mimics the primary level of tissue damage caused by hemorrhage after impact in a car accident. In this way, we tested the hypothesis that the presence of ethanol in combination with hypoxia causes greater cellular damage compared to conditions of ethanol or hypoxia alone. Ethanol, alone and in high concentrations, was found to greatly affect cell function as shown by decreased cellular ATP levels, increased LDH release, and a downregulated expression of CYP2E1 gene. By adding the condition of hypoxia to low concentrations of ethanol, cellular damage increased dramatically as well. Decreased gene expression and protein levels of CYP2E1 correlated with increased hepatocyte injury and thus, this enzyme may significantly contribute to the severity of cellular damage. These results provide useful information for future research on the effects of ethanol in combination with hemorrhage on cells in vitro, simulating the condition of driving while intoxicated and binge drinking.ving while intoxicated and binge drinking.)
Wen 2023 PLoS One + (Alcoholic myopathy is caused by chronic co … Alcoholic myopathy is caused by chronic consumption of alcohol (ethanol) and is characterized by weakness and atrophy of skeletal muscle. Regular exercise is one of the important ways to prevent or alleviate skeletal muscle myopathy. However, the beneficial effects and the exact mechanisms underlying regular exercise on alcohol myopathy remain unclear. In this study, a model of alcoholic myopathy was established using zebrafish soaked in 0.5% ethanol. Additionally, these zebrafish were intervened to swim for 8 weeks at an exercise intensity of 30% of the absolute critical swimming speed (Ucrit), aiming to explore the beneficial effects and underlying mechanisms of regular exercise on alcoholic myopathy. This study found that regular exercise inhibited protein degradation, improved locomotion ability, and increased muscle fiber cross-sectional area (CSA) in ethanol-treated zebrafish. In addition, regular exercise increases the functional activity of mitochondrial respiratory chain (MRC) complexes and upregulates the expression levels of MRC complexes. Regular exercise can also improve oxidative stress and mitochondrial dynamics in zebrafish skeletal muscle induced by ethanol. Additionally, regular exercise can activate mitochondrial biogenesis and inhibit mitochondrial unfolded protein response (UPRmt). Together, our results suggest regular exercise is an effective intervention strategy to improve mitochondrial homeostasis to attenuate alcoholic myopathy.meostasis to attenuate alcoholic myopathy.)

ALGAEUROPE 2018 Amsterdam NL + (AlgaEurope 2018, Amsterdam, Netherlands, 2018)

AlgaEurope 2020 Virtual Event + (AlgaEurope 2020, Virtual Event, 2020, NextGen-O2k)
AlgaEurope 2022 Rome IT + (AlgaEurope 2022, Rome, IT, 2022)
Gnaiger 2022 Abstract Bioblast-PB + (Algal biotechnology has emerged as a high- … Algal biotechnology has emerged as a high-potential industry for efficient and CO2-neutral production of biomass providing biofuels, food and feed, and a variety of carbon-based chemicals and pharmaceuticals. Algal metabolism is directly involved in the regulation of growth, cell concentration, and biosynthesis of biotechnologically-relevant phytochemicals such as vitamins, antioxidants, and immune response boosters. Photoautotrophic growth rates of algae are based on light-to-chemical energy conversion and CO2 fixation, and any optimization of biomass production requires maximizing energy-use efficiency of photosynthesis and respiration, both of which vary as a function of light intensity. As such, the bioenergetic crosstalk between mitochondria and chloroplasts plays a key role in maintaining metabolic integrity and controlling intermediary metabolite production. In the present study, we investigated how photosynthetic O2 production and respiratory O2 consumption was influenced as a function of light intensity, O2 concentration, and culture density in the unicellular model green alga ''Chlamydomonas reinhardtii''. Cultures were grown photoautotrophically in a modified Tris-Phosphate growth medium (TRIS, N- and P-nutrient replete) at 25 °C, pH 7.0, and light intensity of 100 µmol photons·s-1·m-2 (16:8 h light:dark cycle). Kinetics of light-induced O2 production and dark respiration of these microalgae was measured under culture conditions and three cell concentrations, while varying O2 concentrations in the Oroboros [[NextGen-O2k]] equipped with the PhotoBiology-Module [1] during stepwise increases of blue actinic light from from 10 to 350 µmol∙s-1∙m-2, followed by darkness, again at various controlled O2 concentrations. Maximum net photosynthesis was inhibited by 40 % at hyperoxic O2 concentrations of 550 to 650 µM, when ROS production is known to be increased [2,3]. Transient light-enhanced dark respiration [4] peaked within 30 to 60 s after light-dark transitions and was 3.5- to 4-fold higher than steady-state dark respiration independent of O2 concentration in the range of 200 to 650 µM. We conclude that high-resolution photorespiratory analysis provides a new method to investigate the oxygen kinetics of O2 production and O2 consumption that reveal interactions of chloroplasts and mitochondria under precisely regulated experimental light and oxygen regimes.# Went N, Di Marcello M, Gnaiger E (2021) Oxygen dependence of photosynthesis and light-enhanced dark respiration studied by High-Resolution PhotoRespirometry. https://doi.org/10.26124/mitofit:2021-0005# Komlódi T, Sobotka O, Gnaiger E (2021) Facts and artefacts on the oxygen dependence of hydrogen peroxide production using Amplex UltraRed. https://doi.org/10.26124/bec:2021-0004# Shimakawa G, Kohara A, Miyake C (2020) Characterization of light-enhanced respiration in cyanobacteria. https://doi.org/10.3390/ijms22010342drogen peroxide production using Amplex UltraRed. https://doi.org/10.26124/bec:2021-0004 # Shimakawa G, Kohara A, Miyake C (2020) Characterization of light-enhanced respiration in cyanobacteria. https://doi.org/10.3390/ijms22010342 )
Gerisch 2020 Dev Cell + (All animals have evolved the ability to su … All animals have evolved the ability to survive nutrient deprivation, and nutrient signaling pathways are conserved modulators of health and disease. In ''C. elegans'', late-larval starvation provokes the adult reproductive diapause (ARD), a long-lived quiescent state that enables survival for months without food, yet underlying molecular mechanisms remain unknown. Here, we show that ARD is distinct from other forms of diapause, showing little requirement for canonical longevity pathways, autophagy, and fat metabolism. Instead it requires the HLH-30/TFEB transcription factor to promote the morphological and physiological remodeling involved in ARD entry, survival, and recovery, suggesting that HLH-30 is a master regulator of reproductive quiescence. HLH-30 transcriptome and genetic analyses reveal that Max-like HLH factors, AMP-kinase, mTOR, protein synthesis, and mitochondrial fusion are target processes that promote ARD longevity. ARD thus rewires metabolism to ensure long-term survival and may illuminate similar mechanisms acting in stem cell quiescence and long-term fasting.Copyright © 2020 Elsevier Inc. All rights reserved. 2020 Elsevier Inc. All rights reserved.)
Hernansanz-Agustin 2019 bioRxiv + (All metazoans depend on O2</ … All metazoans depend on O2 delivery and consumption by the mitochondrial oxidative phosphorylation (OXPHOS) system to produce energy. A decrease in O2 availability (hypoxia) leads to profound metabolic rewiring. In addition, OXPHOS uses O2 to produce reactive oxygen species (ROS) that can drive cell adaptations through redox signalling, but also trigger cell damage, and both phenomena occur in hypoxia. However, the precise mechanism by which acute hypoxia triggers mitochondrial ROS production is still unknown. Ca2+ is one of the best known examples of an ion acting as a second messenger, yet the role ascribed to Na+ is to serve as a mere mediator of membrane potential and collaborating in ion transport. Here we show that Na+ acts as a second messenger regulating OXPHOS function and ROS production by modulating fluidity of the inner mitochondrial membrane (IMM). We found that a conformational shift in mitochondrial complex I during acute hypoxia drives the acidification of the matrix and solubilization of calcium phosphate precipitates. The concomitant increase in matrix free-Ca2+ activates the mitochondrial Na+/Ca2+ exchanger (NCLX), which imports Na+ into the matrix. Na+ interacts with phospholipids reducing IMM fluidity and mobility of free ubiquinone between complex II and complex III, but not inside supercomplexes. As a consequence, superoxide is produced at complex III, generating a redox signal. Inhibition of mitochondrial Na+ import through NCLX is sufficient to block this pathway, preventing adaptation to hypoxia. These results reveal that Na+ import into the mitochondrial matrix controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences in cellular metabolismlt;/sup> import into the mitochondrial matrix controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences in cellular metabolism)
Hernansanz-Agustin 2020 Nature + (All metazoans depend on the consumption of … All metazoans depend on the consumption of O2 by the mitochondrial oxidative phosphorylation system (OXPHOS) to produce energy. In addition, the OXPHOS uses O2 to produce reactive oxygen species that can drive cell adaptations, a phenomenon that occurs in hypoxia and whose precise mechanism remains unknown. Ca2+ is the best known ion that acts as a second messenger, yet the role ascribed to Na+ is to serve as a mere mediator of membrane potential. Here we show that Na+ acts as a second messenger that regulates OXPHOS function and the production of reactive oxygen species by modulating the fluidity of the inner mitochondrial membrane. A conformational shift in mitochondrial complex I during acute hypoxia drives acidification of the matrix and the release of free Ca2+ from calcium phosphate (CaP) precipitates. The concomitant activation of the mitochondrial Na+/Ca2+ exchanger promotes the import of Na+ into the matrix. Na+ interacts with phospholipids, reducing inner mitochondrial membrane fluidity and the mobility of free ubiquinone between complex II and complex III, but not inside supercomplexes. As a consequence, superoxide is produced at complex III. The inhibition of Na+ import through the Na+/Ca2+ exchanger is sufficient to block this pathway, preventing adaptation to hypoxia. These results reveal that Na+ controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences for cellular metabolism.oxia. These results reveal that Na+ controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences for cellular metabolism.)
Neves 2015 Elife + (All organisms live within a given thermal … All organisms live within a given thermal range, but little is known about the mechanisms setting the limits of this range. We uncovered cellular features exhibiting signature changes at thermal limits in ''Caenorhabditis elegans'' embryos. These included changes in embryo size and shape, which were also observed in ''Caenorhabditis briggsae'', indicating evolutionary conservation. We hypothesized that such changes could reflect restricted aerobic capacity at thermal limits. Accordingly, we uncovered that relative respiration in ''C. elegans'' embryos decreases at the thermal limits as compared to within the thermal range. Furthermore, by compromising components of the respiratory chain, we demonstrated that the reliance on aerobic metabolism is reduced at thermal limits. Moreover, embryos thus compromised exhibited signature changes in size and shape already within the thermal range. We conclude that restricted aerobic metabolism at the thermal limits contributes to setting the thermal range in a metazoan organism. the thermal range in a metazoan organism.)
Wilmshurst 1998 BMJ + (All organisms require oxygen for metabolis … All organisms require oxygen for metabolism, but the oxygen in water is unavailable to mammals. Divers (and diving mammals such as whales and seals) are entirely dependent on the oxygen carried in the air in their lungs or their gas supply. Divers also have a paradoxical problem with oxygen. At higher partial pressures oxygen causes acute toxicity leading to convulsions. To understand the diver's narrow knife edge between fatal hypoxia and fatal hyperoxia we need to recall some of the physical properties of gases. At sea level atmospheric pressure is 1 bar absolute (1 standard atmosphere =101 kPa=1.013 bars). The weight of the atmosphere exerts a pressure which will support a column of water 10 m high; 10 m under water the pressure on a diver is 200 kPa. The volume of gas in an early diving bell full of air at sea level is halved at 10 m according to Boyle's law; at 20 m pressure is 300 kPa absolute and the gas is compressed into one third the volume. Dry air is composed of roughly 21 % oxygen, 78 % nitrogen, and 1 % other gases. According to Dalton's law the partial pressure of oxygen at any depth will be 21 % of the total pressure exerted by the air and the partial pressure of nitrogen will be 78 % of total pressure. Gases dissolve in the liquid with which they are in contact. Nitrogen is fat soluble and at sea level we have several litres dissolved in our bodies. If the partial pressure of nitrogen is doubled (by breathing air at 10 m depth) for long enough for equilibration to take place we will contain twice as many dissolved nitrogen molecules as at sea level. Gases dissolve in the liquid with which they are in contact. Nitrogen is fat soluble and at sea level we have several litres dissolved in our bodies. If the partial pressure of nitrogen is doubled (by breathing air at 10 m depth) for long enough for equilibration to take place we will contain twice as many dissolved nitrogen molecules as at sea level. The effect of the increased partial pressures of oxygen is more complex. Doubling our inspired partial pressure of oxygen doubles the amount of oxygen in solution but does not double the amount of oxygen in the body since a large part of our oxygen content is bound to oxygen carrying pigments. The haemoglobin in arterial blood is virtually saturated at an inspired partial pressure of oxygen (Fio2) of 21 kPa, and increasing the partial pressure of oxygen has little effect on the amount of oxygen bound to haemoglobin.the amount of oxygen bound to haemoglobin.)
Silvia 1976 American Psychological Association + (All students and professors need to write, … All students and professors need to write, and many struggle to finish their stalled dissertations, journal articles, book chapters, or grant proposals. Writing is hard work and can be difficult to wedge into a frenetic academic schedule.In this practical, light-hearted, and encouraging book, Paul Silvia explains that writing productively does not require innate skills or special traits but specific tactics and actions. Drawing examples from his own field of psychology, he shows readers how to overcome motivational roadblocks and become prolific without sacrificing evenings, weekends, and vacations. After describing strategies for writing productively, the author gives detailed advice from the trenches on how to write, submit, revise, and resubmit articles, how to improve writing quality, and how to write and publish academic work.nd how to write and publish academic work.)
Cubizolle 2020 J Cell Mol Med + (All-trans-retinal (atRAL) is a highly reac … All-trans-retinal (atRAL) is a highly reactive carbonyl specie, known for its reactivity on cellular phosphatidylethanolamine in photoreceptor. It is generated by photoisomerization of 11-cis-retinal chromophore linked to opsin by the Schiff's base reaction. In ABCA4-associated autosomal recessive Stargardt macular dystrophy, atRAL results in carbonyl and oxidative stress, which leads to bisretinoid A2E, accumulation in the retinal pigment epithelium (RPE). This A2E-accumulation presents as lipofuscin fluorescent pigment, and its photooxidation causes subsequent damage. Here we describe protection against a lethal dose of atRAL in both photoreceptors and RPE in primary cultures by a lipidic polyphenol derivative, an isopropyl-phloroglucinol linked to DHA, referred to as IP-DHA. Next, we addressed the cellular and molecular defence mechanisms in commonly used human ARPE-19 cells. We determined that both polyunsaturated fatty acid and isopropyl substituents bond to phloroglucinol are essential to confer the highest protection. IP-DHA responds rapidly against the toxicity of atRAL and its protective effect persists. This healthy effect of IP-DHA applies to the mitochondrial respiration. IP-DHA also rescues RPE cells subjected to the toxic effects of A2E after blue light exposure. Together, our findings suggest that the beneficial role of IP-DHA in retinal cells involves both anti-carbonyl and anti-oxidative capacities.© 2020 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.ndation for Cellular and Molecular Medicine.)
Qi 2017 Ann Allergy Asthma Immunol + (Allergic rhinitis is the most common of th … Allergic rhinitis is the most common of the atopic diseases, affecting up to 25% of the population worldwide. Grass pollen sensitization has been recognized as a major cause of allergic rhinitis. On the pathophysiologic level, allergic rhinitis is an IgE-mediated inflammation of the nasal mucosa. Grass pollen allergy, commonly called hay fever, can also cause more general symptoms, such as fatigue and unwellness as seen in flulike syndromes. This might be partly related to the activation of a systemic inflammatory pathway after the local nasal inflammatory response, but data from studies concerning the systemic effects of nasal mucosal allergen exposure are limited....ucosal allergen exposure are limited. ...)
Mutschler 2013 + (Allergien, Burn-out, Fibromyalgie, Multipl … Allergien, Burn-out, Fibromyalgie, Multiple Chemikalien-Sensitivität, Fatigue-Syndrom, … die Liste der Krankheiten, die die herkömmliche Medizin – vor allem für Kassenpatienten – weder gut diagnostizieren noch wirklich erfolgreich behandeln kann, ist lang. Hinzu kommt, dass zu den bereits Genannten fast unbegrenzt weitere Erkrankungen hinzugefügt werden müssen, von denen die Lehrmedizin meint, dass sie sie behandeln kann, ihre Behandlung dem Patienten jedoch oft auch erheblich schadet: Herz-Kreislauf-Erkrankungen, Krebs, Autoimmunerkrankungen, neurodegenerative Erkrankungen, Depressionen und viele mehr. Diese Patienten werden mit einer Reihe von Pharmaka versorgt, die die Symptome der Erkrankung abmildert oder bestenfalls zum Verschwinden bringt, jedoch wird dieser „Erfolg“ mit erheblichen Nebenwirkungen teuer erkauft. Meist ist die jahrzehntelange „Patienten-Karriere“ bereits klar vorgezeichnet, wenn ein Mensch in die Mühle der pharmazeutisch geprägten Medizin gerät. Es ist nur eine Frage der Zeit, wann die nächsten schwerwiegenden Symptome auftreten. Denn viele der millionenfach verschriebenen Arzneien greifen in die Physiologie einer jeden Körperzelle ein und können Stoffwechselwege ausbremsen oder gar Schäden an Organellen erzeugen – allem voran Schäden an den Mitochondrien (sekundäre Mitochondriopathien), den existenziellen Zellbestandteilen für die Energieversorgung in der kleinesten Einheit eines jeden Organs und Gewebes. Ganz zu schweigen davon, dass die ursächlich auslösenden physiologischen Bedingungen weder erkannt noch behoben werden, damit unterschwellig fortbestehen und langfristig folgerichtig weitere, neue Symptome und Erkrankungen zum Vorschein bringen. Wie viel besser steht bei einem Vergleich doch die mitochondriale Medizin mit einer klar definierten Ausrichtung auf die Unterstützung und Förderung der Zellphysiologie da! Sie setzt darauf,die tatsächlichen Belastungen des Körpers und seiner Zellen aufzuspüren und weitestmöglich zu beseitigen,Mängel im Stoffwechsel zu orten und durch eine für den Patienten passende Ernährung und die gezielte Gabe von Makro- und Mikroelementensowie weiteren Vitalstoffen aufzuheben sowie durch geeignete Maßnahmen die Regeneration und die Teilung der Mitochondrien anzuregen und den gesamten Zellstoffwechsel zu unterstützen und zu fördern.So kann mit der Zeit wieder Gesundheit entstehen und tatsächliche Heilung ist möglich.ehen und tatsächliche Heilung ist möglich.)
Kovalev 2018 EMBS + (Allometric decline of mass-specific metabo … Allometric decline of mass-specific metabolic rate with increasing body size in organisms is a long-known and well-documented phenomenon. The patterns observed at the organismal level indicate fundamental allometric changes in the rate of cellular metabolism and mitochondrial functioning; however, the mechanistic causes of these differences remain under debate. The aerobic metabolic rate is performed through the mitochondrial pathway of oxidative phosphorylation. Therefore, it is meaningful to predict that allometric pattern for mitochondrial functioning would reflect the pattern of aerobic metabolism. Surprisingly, there have been relatively few studies that have assessed the possible link between mitochondrial respiration and body size in invertebrates. We studied body size dependence of mitochondrial respiration of blue mussels ''Mytilus edulis'' L. Mussels were of the same age (3 years), but differed in size. In order to test functional capacities of mitochondria from mussels of different sizes respiration was determined at normal (15°C) and elevated (27°C) exposure temperatures. Mitochondria were isolated from hepatopancreas and respiration rate was measured using high-resolution respirometry method (by Oxygraph-2k, Oroboros Instruments). Substrates, inhibitors and uncoupling agents for oxidative phosphorylation (OXPHOS) and electron transport system (ETS) were added step-by-step in order to assess maximal respiration rates, respiratory control ratio, proton leak, activity and impact of all complexes of ETC. Temperature significantly accelerated state 3 (ADP-stimulated) mitochondrial respiration, maximal respiration with uncoupled ETS, and caused an increase of Respiratory Control Ratios. On the contrary, state 4 respiration (indicative of the proton leak) as well as respiration related to electron flux through complexes of ETC did not show an increase at stress temperature (27°C). Body size of mussels had a strong effect on most studied parameters. ADP-stimulated respiration, electron flux through complex IV, proton leak and uncoupled respiration showed a pronounced increase with body mass of mussels with power coefficients of 1.8, 1.2, 0.2 and 0.8, respectively. The obtained results showed that larger mussels had higher OXPHOS rates than smaller ones. Since all mussels were of the same age, larger ones obviously were characterized by rapid growth. It is possible that elevated growth abilities in some specimens compared to the others result from more efficient metabolic regulation which in turn is related to higher mitochondrial capacities.elated to higher mitochondrial capacities.)
Miettinen 2017 Trends Cell Biol + (Allometric scaling of metabolic rate resul … Allometric scaling of metabolic rate results in lower total mitochondrial oxygen consumption with increasing organismal size. This is considered a universal law in biology. Here, we discuss how allometric laws impose size-dependent limits to mitochondrial activity at the cellular level. This cell-size-dependent mitochondrial metabolic activity results in nonlinear scaling of metabolism in proliferating cells, which can explain size homeostasis. The allometry in mitochondrial activity can be controlled through mitochondrial fusion and fission machinery, suggesting that mitochondrial connectivity can bypass transport limitations, the presumed biophysical basis for allometry. As physical size affects cellular functionality, cell-size-dependent metabolism becomes directly relevant for development, metabolic diseases, and aging.evelopment, metabolic diseases, and aging.)
Nold 2019 Psychoneuroendocrinology + (Allostasis is the process by which the bod … Allostasis is the process by which the body’s physiological systems adapt to environmental changes. Chronic stress increases the allostatic load to the body, producing wear and tear that could, over time, become pathological. In this study, young adult male Wistar Kyoto rats were exposed to an unpredictable chronic mild stress (uCMS) protocol to increase allostatic load. First, physiological systems which may be affected by extended uCMS exposure were assessed. Secondly, 5 weeks of uCMS were used to investigate early adaptations in the previously selected systems. Adverse experiences during developmentally sensitive periods like adolescence are known to severely alter the individual stress vulnerability with long-lasting effects. To elucidate how early life adversity impacts stress reactivity in adulthood, an additional group with juvenile single-housing (JSH) prior to uCMS was included in the second cohort. The aim of this work was to assess the impact of chronic stress with or without adversity during adolescence on two domains known to be impacted in numerous stress-related disorders: mitochondrial energy metabolism and the immune system. Both, uCMS and adolescence stress increased kynurenine and kynurenic acid in plasma, suggesting a protective, anti-oxidant response from the kynurenine pathway. Furthermore, uCMS resulted in a down-regulation of immediate early gene expression in the prefrontal cortex and hippocampus, while only rats with the double-hit of adolescent stress and uCMS demonstrated increased mitochondrial activity in the hippocampus. These results suggest that early life adversity may impact on allostatic load by increasing energetic requirements in the brain.asing energetic requirements in the brain.)
Opperdoes 2024 BMC Genomics + (Almost all extant organisms use the same, … Almost all extant organisms use the same, so-called canonical, genetic code with departures from it being very rare. Even more exceptional are the instances when a eukaryote with non-canonical code can be easily cultivated and has its whole genome and transcriptome sequenced. This is the case of ''Blastocrithidia nonstop'', a trypanosomatid flagellate that reassigned all three stop codons to encode amino acids.We ''in silico'' predicted the metabolism of ''B. nonstop'' and compared it with that of the well-studied human parasites ''Trypanosoma brucei'' and ''Leishmania major''. The mapped mitochondrial, glycosomal and cytosolic metabolism contains all typical features of these diverse and important parasites. We also provided experimental validation for some of the predicted observations, concerning, specifically presence of glycosomes, cellular respiration, and assembly of the respiratory complexes.In an unusual comparison of metabolism between a parasitic protist with a massively altered genetic code and its close relatives that rely on a canonical code we showed that the dramatic differences on the level of nucleic acids do not seem to be reflected in the metabolisms. Moreover, although the genome of ''B. nonstop'' is extremely AT-rich, we could not find any alterations of its pyrimidine synthesis pathway when compared to other trypanosomatids. Hence, we conclude that the dramatic alteration of the genetic code of ''B. nonstop'' has no significant repercussions on the metabolism of this flagellate.ions on the metabolism of this flagellate.)
Zhu 2019 Aging Cell + (Alogliptin is a commonly prescribed drug t … Alogliptin is a commonly prescribed drug treating patients with type 2 diabetes. Here, we show that long-term intervention with alogliptin (0.03% w/w in diet) improves survival and health of mice on a high-fat diet. Alogliptin intervention takes beneficial effects associated with longevity, including increased insulin sensitivity, attenuated functionality decline, decreased organ pathology, preserved mitochondrial function, and reduced oxidative stress. Autophagy activation is proposed as an underlying mechanism of these beneficial effects. We conclude that alogliptin intervention could be considered as a potential strategy for extending lifespan and healthspan in obesity and overweight.© 2019 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.mical Society and John Wiley & Sons Ltd.)
Dieter 2022 Int J Mol Sci + (Alpha lipoic acid (ALA) is a sulphur-conta … Alpha lipoic acid (ALA) is a sulphur-containing organic compound, derived from octanoic acid, and an important cofactor for mitochondrial respiratory enzymes. It has strong antioxidant properties that improve mitochondrial function. We investigated if ALA improves mitochondrial dysfunction in a cellular model of Alzheimer's disease (AD).SH-SY5Y-APP695 cells were used as a model for an early stage of AD. Vector-transfected SH-SY5Y-MOCK cells served as controls. Using these cells, we investigated mitochondrial respiration (OXPHOS), mitochondrial membrane potential (MMP), adenosine triphosphate (ATP) production, and citrate synthase activity (CS) in cells treated with ALA. Cells were treated for 24 h with different concentrations of ALA and with or without the complex I inhibitor rotenone.Incubation with ALA showed a significant increase in ATP levels in both SH-SY5Y-APP695 and SH-SY5Y-MOCK cells. MMP levels were elevated in SH-SY5Y-MOCK cells, treatment with rotenone showed a reduction in MMP, which could be partly alleviated after incubation with ALA in SH-SY5Y-MOCK cells. ALA treatment showed significant differences in respiration chain complex activities in SH-SY5Y-MOCK cells. Citrate synthase activity was unaffected. ROS levels were significantly lower in both cell lines treated with ALA.ALA increased the activity of the different complexes of the respiratory chain, and consequently enhanced the MMP, leading to increased ATP levels indicating improved mitochondrial function. ALA only marginally protects from additional rotenone-induced mitochondrial stress.ly protects from additional rotenone-induced mitochondrial stress.)
Tretter 2005 Philos Trans R Soc Lond B Biol Sci + (Alpha-ketoglutarate dehydrogenase (alpha-K … Alpha-ketoglutarate dehydrogenase (alpha-KGDH) is a highly regulated enzyme, which could determine the metabolic flux through the Krebs cycle. It catalyses the conversion of alpha-ketoglutarate to succinyl-CoA and produces NADH directly providing electrons for the respiratory chain. alpha-KGDH is sensitive to reactive oxygen species (ROS) and inhibition of this enzyme could be critical in the metabolic deficiency induced by oxidative stress. Aconitase in the Krebs cycle is more vulnerable than alpha-KGDH to ROS but as long as alpha-KGDH is functional NADH generation in the Krebs cycle is maintained. NADH supply to the respiratory chain is limited only when alpha-KGDH is also inhibited by ROS. In addition being a key target, alpha-KGDH is able to generate ROS during its catalytic function, which is regulated by the NADH/NAD+ ratio. The pathological relevance of these two features of alpha-KGDH is discussed in this review, particularly in relation to neurodegeneration, as an impaired function of this enzyme has been found to be characteristic for several neurodegenerative diseases.ic for several neurodegenerative diseases.)
Dohlmann 2013 Abstract IOC75 + (Alteration in mitochondrial respiratory ca … Alteration in mitochondrial respiratory capacity has been linked to several conditions that are associated with a sedentary lifestyle, such as obesity and insulin resistance. It is well known that endurance training can diminish these conditions, but some high intensity interval training (HIIT) protocols have shown similar improvements in insulin sensitivity, in spite of the reduced training volume. However it is sparse with literature regarding HIIT and the effect on mitochondrial respiratory capacity. The aim of this study was to investigate the effects of a low volume HIIT protocol on mitochondrial respiratory capacity and VO2max in sedentary overweight adults. 8 healthy sedentary men (n=2) and women (n=6) (age 40±3 yrs, BMI 32±2, VO2max 2383 ±115 ml•min-1) were recruited for this study. They underwent 6 weeks of supervised HIIT on a cycle ergometer (18 sessions of 7x1min exercise bouts interspersed with 1min rest periods). Muscle biopsies were taken from m. vastus lateralis before and after training. Mitochondrial respiratory capacity was measured ex vivo in permeabilized muscle fibers using high resolution respirometry (Oxygraph-2k, Oroboros, Innsbruck, Austria). The respiratory protocol investigated maximal coupled state 3 respiration (complex I + II linked substrates) with the following substrates (malate, glutamate, octanoyl carnitine, succinate and ADP; GMSO3), as well as state 4o (oligomycin; LEAK). Body composition was measured by DXA, and VO2max using an incremental cycle test to exhaustion. Mitochondrial respiratory capacity increased significantly following training; GMSO3 respiration increased by 13% (57± 4 to 64±5 pmol O2•mg-1•s-1) and LEAK respiration increased by 24% (21±2 to 25±2 pmol O2 •mg-1•s-1).The present training protocol didn’t elicit a significant improvement in VO2max (4%, P = 0.37), but time to fatigue during the VO2max test was significantly increased by 18% post training (P <0.001). BMI and body composition were not changed following training.Interestingly the present training protocol induced a significant improvement in mitochondrial respiratory capacity, but not in whole body VO2max, thus implying that the training stimulus was adequate to improve the respiratory capacity locally. The observed improvement in mitochondrial respiratory capacity and time to fatigue suggest that the HIIT training may induce positive metabolic effects that can attenuate the development of lifestyle diseases, independently of VO2max.The project is funded by the EU FP7 program The project is funded by the EU FP7 program)
Rigoni 2016 Abstract Mito Xmas Meeting Innsbruck + (Alteration of mitochondrial ultrastructure … Alteration of mitochondrial ultrastructure has emerged as phenotypical marker of dysfunction. In particular, changes in cristae shape and number regulate the respiratory efficiency of the cell and the release of proapoptotic factors. Moreover, in the last years a growing number of studies have observed a loss of mtDNA associated to mitochondrial related disorders but whether and how mtDNA and nucleoids regulation is influenced by mitochondrial ultrastructure is unknown. To address this question we studied nucleoids distribution and mtDNA copynumber in cellular models where the mitochondrial ultrastructure has been altered. We show that nucleoids distribution vary depending on mitochondrial ultrastructure and accordingly also mtDNA copy number. Furthermore, we have identified a mitochondrial complex that decrease with nucleoids suggesting a relevant role of this complex for nucleoids and mtDNA stability. Our results suggest that nucleoids and mtDNA stability is regulated by mitochondrial ultrastructure.regulated by mitochondrial ultrastructure.)
Schneeberger 2015 Cell Rep + (Alterations in ER homeostasis have been im … Alterations in ER homeostasis have been implicated in the pathophysiology of obesity and type-2 diabetes (T2D). Acute ER stress induction in the hypothalamus produces glucose metabolism perturbations. However, the neurobiological basis linking hypothalamic ER stress with abnormal glucose metabolism remains unknown. Here, we report that genetic and induced models of hypothalamic ER stress are associated with alterations in systemic glucose homeostasis due to increased gluconeogenesis (GNG) independent of body weight changes. Defective alpha melanocyte-stimulating hormone (α-MSH) production underlies this metabolic phenotype, as pharmacological strategies aimed at rescuing hypothalamic α-MSH content reversed this phenotype at metabolic and molecular level. Collectively, our results posit defective α-MSH processing as a fundamental mediator of enhanced GNG in the context of hypothalamic ER stress and establish α-MSH deficiency in proopiomelanocortin (POMC) neurons as a potential contributor to the pathophysiology of T2D.contributor to the pathophysiology of T2D.)
Beaudoin 2014 J Physiol + (Alterations in lipid metabolism within the … Alterations in lipid metabolism within the heart may have a causal role in the establishment of diabetic cardiomyopathy, however this remains equivocal. Therefore, in the current study we determined cardiac mitochondrial bioenergetics in ZDF rats before overt type 2 diabetes and diabetic cardiomyopathy developed. In addition, we utilized resveratrol, a compound previously shown to improve prevent or reverse cardiac dysfunction in high fat-fed rodents, as a tool to potential recover dysfunctions within mitochondria. Fasting blood glucose and invasive left ventricular hemodynamic analysis confirmed the absence of type 2 diabetes and diabetic cardiomyopathy. However, fibrosis was already increased (P<0.05) ~70% in ZDF rats at this early stage in disease progression. Assessments of mitochondrial ADP and pyruvate respiratory kinetics in permeabilized fibres from the left ventricle revealed normal electron transport chain function and content. In contrast, the apparent Km to palmitoyl-CoA (P-CoA) was increased (P<0.05) ~60%, which was associated with an accumulation of intracellular triacylgycerol, diacylglycerol and ceramide species. In addition, the capacity for mitochondrial ROS emission was increased (P<0.05) ~3-fold in ZDF rats. The provision of resveratrol recovered fibrosis, P-CoA respiratory sensitivity, reactive lipid accumulation and mitochondrial reactive oxygen species emission rates. Altogether the current data supports the supposition that a chronic dysfunction within mitochondrial lipid-supported bioenergetics contributes to the development of diabetic cardiomyopathy, as this was present before overt diabetes or cardiac dysfunction. In addition, we show resveratrol supplementation prevents these changes, supporting the belief that resveratrol is a potent therapeutic approach for preventing diabetic cardiomyopathy.ic approach for preventing diabetic cardiomyopathy.)
Lores-Arnaiz 2016 Neurochem Res + (Alterations in mitochondrial bioenergetics … Alterations in mitochondrial bioenergetics have been associated with brain aging. In order to evaluate the susceptibility of brain cortex synaptosomes and non-synaptic mitochondria to aging-dependent dysfunction, male Swiss mice of 3 or 17 months old were used. Mitochondrial function was evaluated by oxygen consumption, mitochondrial membrane potential and respiratory complexes activity, together with UCP-2 protein expression. Basal respiration and respiration driving proton LEAK were decreased by 26 and 33 % in synaptosomes from 17-months old mice, but spare respiratory capacity was not modified by aging. Succinate supported state 3 respiratory rate was decreased by 45 % in brain cortex non-synaptic mitochondria from 17-month-old mice, as compared with young animals, but respiratory control was not affected. Synaptosomal mitochondria would be susceptible to undergo calcium-induced depolarization in 17 months-old mice, while non-synaptic mitochondria would not be affected by calcium overload. UCP-2 was significantly up-regulated in both synaptosomal and submitochondrial membranes from 17-months old mice, compared to young animals. UCP-2 upregulation seems to be a possible mechanism by which mitochondria would be resistant to suffer oxidative damage during aging.t to suffer oxidative damage during aging.)
Fahlbusch 2022 Int J Mol Sci + (Alterations in mitochondrial function are … Alterations in mitochondrial function are an important control variable in the progression of metabolic dysfunction-associated fatty liver disease (MAFLD), while also noted by increased de novo lipogenesis (DNL) and hepatic insulin resistance. We hypothesized that the organization and function of a mitochondrial electron transport chain (ETC) in this pathologic condition is a consequence of shifted substrate availability. We addressed this question using a transgenic mouse model with increased hepatic insulin resistance and DNL due to constitutively active human SREBP-1c. The abundance of ETC complex subunits and components of key metabolic pathways are regulated in the liver of these animals. Further omics approaches combined with functional assays in isolated liver mitochondria and primary hepatocytes revealed that the SREBP-1c-forced fatty liver induced a substrate limitation for oxidative phosphorylation, inducing enhanced complex II activity. The observed increased expression of mitochondrial genes may have indicated a counteraction. In conclusion, a shift of available substrates directed toward activated DNL results in increased electron flows, mainly through complex II, to compensate for the increased energy demand of the cell. The reorganization of key compounds in energy metabolism observed in the SREBP-1c animal model might explain the initial increase in mitochondrial function observed in the early stages of human MAFLD.served in the early stages of human MAFLD.)
Huetter 2006 Exp Gerontol + (Alterations in mitochondrial function are … Alterations in mitochondrial function are believed to play a major role in aging processes in many species, including fungi and animals, and increased oxidative stress is considered a major consequence of altered mitochondrial function. In support of this theory, a lot of correlative evidence has been collected, suggesting that changes in mitochondrial DNA accumulate with age in certain tissues. Furthermore, genetic experiments from lower eukaryotic model organisms, indicate a strong correlative link between increased resistance to oxidative stress and an extended lifespan; in addition, limited experimental evidence suggests that the inhibition of mitochondrial function by selected pharmacologically active compounds can extend lifespan in certain species. However, changes in mitochondrial function may affect aging in a different way in various tissues, and a clear statement about the role of mitochondrial deterioration during physiological aging is missing for most if not all species.At this point, respirometric analyses of mitochondrial function provide a tool to study age-associated changes in mitochondrial respiratory chain function and mitochondrial ATP production within living cells and isolated mitochondria. In the recent years, new instruments have been developed, which allow for an unprecedented high-resolution respirometry, which enables us to determine many parameters of mitochondrial function in routine assays using small samples of biological material. It is conceivable that this technology will become an important tool for all those, who are interested in experimentally addressing the mitochondrial theory of aging. In this article, we provide a synopsis of traditional respirometry and the advances of modern high-resolution respirometry, and discuss how future applications of this technology to recentlyestablished experimental models in aging research may provide exciting new insights into the role of mitochondria in the aging process.role of mitochondria in the aging process.)
Harmuth 2018 Front Mol Neurosci + (Alterations in mitochondrial morphology an … Alterations in mitochondrial morphology and function have been linked to neurodegenerative diseases, including Parkinson disease, Alzheimer disease and Huntington disease. Metabolic defects, resulting from dysfunctional mitochondria, have been reported in patients and respective animal models of all those diseases. Spinocerebellar Ataxia Type 3 (SCA3), another neurodegenerative disorder, also presents with metabolic defects and loss of body weight in early disease stages although the possible role of mitochondrial dysfunction in SCA3 pathology is still to be determined. Interestingly, the SCA3 disease protein ataxin-3, which is predominantly localized in cytoplasm and nucleus, has also been associated with mitochondria in both its mutant and wildtype form. This observation provides an interesting link to a potential mitochondrial involvement of mutant ataxin-3 in SCA3 pathogenesis. Furthermore, proteolytic cleavage of ataxin-3 has been shown to produce toxic fragments and even overexpression of artificially truncated forms of ataxin-3 resulted in mitochondria deficits. Therefore, we analyzed the repercussions of expressing a naturally occurring N-terminal cleavage fragment of ataxin-3 and the influence of an endogenous expression of the S256 cleavage fragment ''in vitro'' and ''in vivo''. In our study, expression of a fragment derived from calpain cleavage induced mitochondrial fragmentation and cristae alterations leading to a significantly decreased capacity of mitochondrial respiration and contributing to an increased susceptibility to apoptosis. Furthermore, analyzing mitophagy revealed activation of autophagy in the early pathogenesis with reduced lysosomal activity. In conclusion, our findings indicate that cleavage of ataxin-3 by calpains results in fragments which interfere with mitochondrial function and mitochondrial degradation processes.n and mitochondrial degradation processes.)
Buck 2017 PLOS ONE + (Alterations in mitochondrial respiration a … Alterations in mitochondrial respiration are an important hallmark of Huntington's disease (HD), one of the most common monogenetic causes of neurodegeneration. The ubiquitous expression of the disease causing mutant huntingtin gene raises the prospect that mitochondrial respiratory deficits can be detected in skeletal muscle. While this tissue is readily accessible in humans, transgenic animal models offer the opportunity to cross-validate findings and allow for comparisons across organs, including the brain. The integrated respiratory chain function of the human ''vastus lateralis'' muscle was measured by high-resolution respirometry (HRR) in freshly taken fine-needle biopsies from seven pre-manifest HD expansion mutation carriers and nine controls. The respiratory parameters were unaffected. For comparison skeletal muscle isolated from HD knock-in mice (HdhQ111) as well as a broader spectrum of tissues including cortex, liver and heart muscle were examined by HRR. Significant changes of mitochondrial respiration in the HdhQ knock-in mouse model were restricted to the liver and the cortex. Mitochondrial mass as quantified by mitochondrial DNA copy number and citrate synthase activity was stable in murine HD-model tissue compared to control. mRNA levels of key enzymes were determined to characterize mitochondrial metabolic pathways in HdhQ mice. We demonstrated the feasibility to perform high-resolution respirometry measurements from small human HD muscle biopsies. Furthermore, we conclude that alterations in respiratory parameters of pre-manifest human muscle biopsies are rather limited and mirrored by a similar absence of marked alterations in HdhQ skeletal muscle. In contrast, the HdhQ111 murine cortex and liver did show respiratory alterations highlighting the tissue specific nature of mutant huntingtin effects on respiration. mutant huntingtin effects on respiration.)
Ekbal 2013 Chest + (Alterations in oxygen transport and use ar … Alterations in oxygen transport and use are integral to the development of multiple organ failure; therefore, the ultimate goal of resuscitation is to restore effective tissue oxygenation and cellular metabolism. Hemodynamic monitoring is the cornerstone of management to promptly identify and appropriately manage (impending) organ dysfunction. Prospective randomized trials have confirmed outcome benefit when preemptive or early treatment is directed toward maintaining or restoring adequate tissue perfusion. However, treatment end points remain controversial, in large part because of current difficulties in determining what constitutes "optimal." Information gained from global whole-body monitoring may not detect regional organ perfusion abnormalities until they are well advanced. Conversely, the ideal "canary" organ that is readily accessible for monitoring, yet offers an early and sensitive indicator of tissue "unwellness," remains to be firmly identified. This review describes techniques available for real-time monitoring of tissue perfusion and metabolism and highlights novel developments that may complement or even supersede current tools.omplement or even supersede current tools.)
Schaefer 2017 Neurophotonics + (Alterations of cellular bioenergetics are … Alterations of cellular bioenergetics are a common feature in most neurodegenerative disorders. However, there is a selective vulnerability of different brain regions, cell types, and even mitochondrial populations to these metabolic disturbances. Thus, the aim of our study was to establish and validate an ''in vivo'' metabolic imaging technique to screen for mitochondrial function on the subcellular level. Based on nicotinamide adenine dinucleotide (phosphate) fluorescence lifetime imaging microscopy [NAD(P)H FLIM], we performed a quantitative correlation to high-resolution respirometry. Thereby, we revealed mitochondrial matrix pH as a decisive factor in imaging NAD(P)H redox state. By combining both parameters, we illustrate a quantitative, high-resolution assessment of mitochondrial function in metabolically modified cells as well as in an amyloid precursor protein-overexpressing model of Alzheimer's disease. Our metabolic imaging technique provides the basis for dissecting mitochondrial deficits not only in a range of neurodegenerative diseases, shedding light onto bioenergetic failures of cells remaining in their metabolic microenvironment.ining in their metabolic microenvironment.)
Koliaki 2013 Mol Cell Endocrinol + (Alterations of hepatic mitochondrial funct … Alterations of hepatic mitochondrial function have been observed in states of insulin resistance and non-alcoholic fatty liver disease (NAFLD). Patients with overt type 2 diabetes mellitus (T2DM) can exhibit reduction in hepatic adenosine triphosphate (ATP) synthesis and impaired repletion of their hepatic ATP stores upon ATP depletion by fructose. Obesity and NAFLD may also associate with impaired ATP recovery after ATP-depleting challenges and augmented oxidative stress in the liver. On the other hand, patients with obesity or NAFLD can present with upregulated hepatic anaplerotic and oxidative fluxes, including β-oxidation and tricarboxylic cycle activity. The present review focuses on the methods and data on hepatic energy metabolism in various states of human insulin resistance. We propose that the liver can adapt to increased lipid exposition by greater lipid storing and oxidative capacity, resulting in increased oxidative stress, which in turn could deteriorate hepatic mitochondrial function in chronic insulin resistance and NAFLD.n in chronic insulin resistance and NAFLD.)
Fazzini 2016 Abstract Mito Xmas Meeting Innsbruck + (Alterations of mitochondrial DNA (mtDNA) c … Alterations of mitochondrial DNA (mtDNA) copy number appear to be associated with several pathologies including encephalopathies and neuropathies as well as the process of aging [1-2].The aim of this study was to set up a reliable quantitative PCR based assay for mitochondrial DNA copy number determination meeting quality requirements for mtDNA specificity.We established a duplex quantitative PCR assay that allows for targeting a single copy nuclear gene (ß2-microglobulin) and the mtDNA (t-RNA Leu) simultaneously. The use of a plasmid containing both targets in a 1:1 ratio was used to normalize against differences in emission intensities of the fluorescent dyes VIC and FAM. QPCR on the serial dilution of the calibrator plasmid revealed that the FAM dye emission signal exceeded the VIC signal, resulting in a ΔCT value of up to 1.2 cycles corresponding to more than a double amount of molecules. Using the plasmid calibrator with internal positive controls reduced the intra-assay variability from 21% (uncorrected) to 7% (plasmid corrected). We evaluated the applicability of the method by using DNA samples that were isolated with different methods and revealed significantly different numbers of mtDNA copies (copy number ratio: salting out/magnetic beads = 1.65).We developed a sensitive and robust assay for mitochondrial copy number detection relative to nuclear DNA. The use of the dual insert calibrator plasmid allows for correction against unequal emission intensities of the differently fluorescence labelled targets. Furthermore, we discovered that the diverse extraction methods selectively isolate different DNA molecules within a sample.e different DNA molecules within a sample.)
Pak 2013 Am J Respir Cell Mol Biol + (Alterations of mitochondrial membrane pote … Alterations of mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and mitochondrial respiration are possible triggers of pulmonary vascular remodeling in pulmonary hypertension (PH). We investigated the role of MMP in PH and hypothesized that deletion of the mitochondrial uncoupling protein 2 (UCP2) increases MMP, thus promoting pulmonary vascular remodeling and PH. MMP was measured by JC-1 in isolated pulmonary arterial smooth muscle cells (PASMCs) of patients with PH and animals with PH induced by exposure to monocrotaline (MCT) or chronic hypoxia. PH was quantified ''in vivo'' in UCP2-deficient (UCP2(-/-)) mice by hemodynamics, morphometry, and echocardiography. ROS were measured by electron spin resonance spectroscopy and proliferation by thymidine incorporation. Mitochondrial respiration was investigated by high-resolution respirometry. MMP was increased in PASMCs of patients and in animal models of PH. UCP2(-/-) mice exhibited pulmonary vascular remodeling and mild PH compared with wild-type (WT) mice. PASMCs of UCP2(-/-) mice showed increased proliferation, MMP, and ROS release. Increased proliferation of UCP2(-/-) PASMCs could be attenuated by ROS inhibitors and inhibited by carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone, which decreased MMP to the level of WT mice. Mitochondrial respiration was altered in PASMCs from MCT rats and PASMCs exposed to hypoxia but not in isolated pulmonary mitochondria of UCP2(-/-) mice or PASMCs after treatment with small interfering RNA for UCP2. Our data suggest that increased MMP causes vascular remodeling in UCP2(-/-) mice partially via increased ROS. In chronic hypoxia and MCT-induced PH, additional pathomechanisms such as decreased respiration may play a role. as decreased respiration may play a role.)
Goldberg 2019 Biochem J + (Alterations to branched-chain keto acid (B … Alterations to branched-chain keto acid (BCKA) oxidation have been implicated in a wide variety of human diseases, ranging from diabetes to cancer. Although global shifts in BCKA metabolism-evident by gene transcription, metabolite profiling, and ''in vivo'' flux analyses have been documented across various pathological conditions, the underlying biochemical mechanism(s) within the mitochondrion remain largely unknown. ''In vitro'' experiments using isolated mitochondria represent a powerful biochemical tool for elucidating the role of the mitochondrion in driving disease. Such analyses have routinely been utilized across disciplines to shed valuable insight into mitochondrial-linked pathologies. That said, few studies have attempted to model ''in vitro'' BCKA oxidation in isolated organelles. The impetus for the present study stemmed from the knowledge that complete oxidation of each of the three BCKAs involves a reaction dependent upon bicarbonate and ATP, both of which are not typically included in respiration experiments. Based on this, it was hypothesized that the inclusion of exogenous bicarbonate and stimulation of respiration using physiological shifts in ATP-free energy, rather than excess ADP, would allow for maximal BCKA-supported respiratory flux in isolated mitochondria. This hypothesis was confirmed in mitochondria from several mouse tissues, including heart, liver and skeletal muscle. What follows is a thorough characterization and validation of a novel biochemical tool for investigating BCKA metabolism in isolated mitochondria.© 2019 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.ed on behalf of the Biochemical Society.)
Goldberg 2021 Biochem J + (Alterations to branched-chain keto acid (B … Alterations to branched-chain keto acid (BCKA) oxidation have been implicated in a wide variety of human diseases, ranging from diabetes to cancer. Although global shifts in BCKA metabolism-evident by gene transcription, metabolite profiling, and ''in vivo'' flux analyses have been documented across various pathological conditions, the underlying biochemical mechanism(s) within the mitochondrion remain largely unknown. ''In vitro'' experiments using isolated mitochondria represent a powerful biochemical tool for elucidating the role of the mitochondrion in driving disease. Such analyses have routinely been utilized across disciplines to shed valuable insight into mitochondrial-linked pathologies. That said, few studies have attempted to model ''in vitro'' BCKA oxidation in isolated organelles. The impetus for the present study stemmed from the knowledge that complete oxidation of each of the three BCKAs involves a reaction dependent upon bicarbonate and ATP, both of which are not typically included in respiration experiments. Based on this, it was hypothesized that the inclusion of exogenous bicarbonate and stimulation of respiration using physiological shifts in ATP-free energy, rather than excess ADP, would allow for maximal BCKA-supported respiratory flux in isolated mitochondria. This hypothesis was confirmed in mitochondria from several mouse tissues, including heart, liver and skeletal muscle. What follows is a thorough characterization and validation of a novel biochemical tool for investigating BCKA metabolism in isolated mitochondria. BCKA metabolism in isolated mitochondria.)
Fisar 2019 Clin Biochem + (Altered amyloid metabolism and mitochondri … Altered amyloid metabolism and mitochondrial dysfunction play key roles in the development of Alzheimer's disease (AD). We asked whether an association exists between disturbed platelet mitochondrial respiration and the plasma concentrations of Aβ40 and Aβ42 in patients with AD.Plasma Aβ40 and Aβ42 concentrations and mitochondrial respiration in intact and permeabilized platelets were measured in 50 patients with AD, 15 patients with vascular dementia and 25 control subjects. A pilot longitudinal study was performed to monitor the progression of AD in a subgroup 11 patients with AD.The mean Aβ40, Aβ42 and Aβ42/Aβ40 levels were not significantly altered in patients with AD compared with controls. The mitochondrial respiratory rate in intact platelets was significantly reduced in patients with AD compared to controls, particularly the basal respiratory rate, maximum respiratory capacity, and respiratory reserve; however, the flux control ratio for basal respiration was increased. A correlation between the plasma Aβ42 concentration and mitochondrial respiration in both intact and permeabilized platelets differs in controls and patients with AD.Based on our data, (1) mitochondrial respiration in intact platelets, but not the Aβ level itself, may be included in a panel of biomarkers for AD; (2) dysfunctional mitochondrial respiration in platelets is not explained by changes in plasma Aβ concentrations; and (3) the association between mitochondrial respiration in platelets and plasma Aβ levels differs in patients with AD and controls. The results supported the hypothesis that mitochondrial dysfunction is the primary factor contributing to the development of AD.Copyright © 2019. Published by Elsevier Inc.at mitochondrial dysfunction is the primary factor contributing to the development of AD. Copyright © 2019. Published by Elsevier Inc.)
Chowdhury 2018 Oxid Med Cell Longev + (Altered cellular metabolism is considered … Altered cellular metabolism is considered a hallmark of cancer and is fast becoming an avenue for therapeutic intervention. Mitochondria have recently been viewed as an important cellular compartment that fuels the metabolic demands of cancer cells. Mitochondria are the major source of ATP and metabolites necessary to fulfill the bioenergetics and biosynthetic demands of cancer cells. Furthermore, mitochondria are central to cell death and the main source for generation of reactive oxygen species (ROS). Overall, the growing evidence now suggests that mitochondrial bioenergetics, biogenesis, ROS production, and adaptation to intrinsic oxidative stress are elevated in chronic lymphocytic leukemia (CLL). Hence, recent studies have shown that mitochondrial metabolism could be targeted for cancer therapy. This review focuses the recent advancements in targeting mitochondrial metabolism for the treatment of CLL.drial metabolism for the treatment of CLL.)
Schoepf 2016 FEBS J + (Altered mitochondrial metabolism plays a p … Altered mitochondrial metabolism plays a pivotal role in the development and progression of various diseases, including cancer. Cell lines are frequently used as models to study mitochondrial (dys)function but little is known about their mitochondrial respiration and metabolic properties in comparison to the primary tissue of origin. We have developed a method for assessment of oxidative phosphorylation in prostate tissue samples of only 2 mg wet weight using high-resolution respirometry. Reliable protocols were established to investigate the respiratory activity of different segments of the mitochondrial electron transfer-pathway in mechanically permeabilized tissue biopsies. Additionally, the widely used immortalized prostate epithelial and fibroblast cell lines RWPE1 and NAF, representing the major cell types in prostate tissue, were analyzed and compared to the tissue of origin. Our results show that mechanical treatment without chemical permeabilization agents or sample processing constitutes a reliable preparation method for OXPHOS analysis in small amounts of prostatic tissue typically obtained by prostate biopsy. The cell lines represented the bioenergetic properties of fresh tissue to a limited extent only. Particularly, tissue showed a higher oxidative capacity with succinate and glutamate, whereas pyruvate was a substrate supporting significantly higher respiratory activities in cell lines. Several fold higher zinc levels measured in tissue compared to cells confirmed the role of aconitase for prostate specific metabolism in agreement with observed respiratory properties. In conclusion, combining the flexibility of cell culture models and tissue samples for respirometric analysis are powerful tools for investigation of mitochondrial function and tissue specific metabolism. n and tissue specific metabolism. )
Kupats 2020 Oxid Med Cell Longev + (Altered neuronal Ca2+</sup&g … Altered neuronal Ca2+ homeostasis and mitochondrial dysfunction play a central role in the pathogenesis of traumatic brain injury (TBI). R-Phenibut ((3R)-phenyl-4-aminobutyric acid) is an antagonist of the α2δ subunit of voltage-dependent calcium channels (VDCC) and an agonist of gamma-aminobutyric acid B (GABA-B) receptors. The aim of this study was to evaluate the potential therapeutic effects of R-phenibut following the lateral fluid percussion injury (latFPI) model of TBI in mice and the impact of R- and S-phenibut on mitochondrial functionality ''in vitro''. By determining the bioavailability of R-phenibut in the mouse brain tissue and plasma, we found that R-phenibut (50 mg/kg) reached the brain tissue 15 min after intraperitoneal (i.p.) and peroral (p.o.) injections. The maximal concentration of R-phenibut in the brain tissues was 0.6 μg/g and 0.2 μg/g tissue after i.p. and p.o. administration, respectively. Male Swiss-Webster mice received i.p. injections of R-phenibut at doses of 10 or 50 mg/kg 2 h after TBI and then once daily for 7 days. R-Phenibut treatment at the dose of 50 mg/kg significantly ameliorated functional deficits after TBI on postinjury days 1, 4, and 7. Seven days after TBI, the number of Nissl-stained dark neurons (N-DNs) and interleukin-1beta (IL-1β) expression in the cerebral neocortex in the area of cortical impact were reduced. Moreover, the addition of R- and S-phenibut at a concentration of 0.5 μg/ml inhibited calcium-induced mitochondrial swelling in the brain homogenate and prevented anoxia-reoxygenation-induced increases in mitochondrial H2O2 production and the H2O2/O ratio. Taken together, these results suggest that R-phenibut could serve as a neuroprotective agent and promising drug candidate for treating TBI.erve as a neuroprotective agent and promising drug candidate for treating TBI.)
Porter 2015 Burns + (Altered skeletal muscle mitochondrial func … Altered skeletal muscle mitochondrial function contributes to the pathophysiological stress response to burns. However, the acute and chronic impact of burn trauma on skeletal muscle bioenergetics remains poorly understood. Here, we determined the temporal relationship between burn trauma and mitochondrial function in murine skeletal muscle local to and distal from burn wounds. Male BALB/c mice (8-10 weeks old) were burned by submersion of the dorsum in water (∼95°C) to create a full thickness burn on ∼30% of the body. Skeletal muscle was harvested spinotrapezius underneath burn wounds (local) and the quadriceps (distal) of sham and burn treated mice at 3h, 24h, 4d and 10d post-injury. Mitochondrial respiration was determined in permeabilized myofiber bundles by high-resolution respirometry. Caspase 9 and caspase 3 protein concentration were determined by western blot. In muscle local to burn wounds, respiration coupled to ATP production was significantly diminished at 3h and 24h post-injury (''P''<0.001), as was mitochondrial coupling control (''P''<0.001). There was a 5- (''P''<0.05) and 8-fold (''P''<0.001) increase in respiration in response to cytochrome at 3h and 24h post burn, respectively, indicating damage to the outer mitochondrial membranes. Moreover, we also observed greater active caspase 9 and caspase 3 in muscle local to burn wounds, indicating the induction of apoptosis. Distal muscle mitochondrial function was unaltered by burn trauma until 10d post burn, where both respiratory capacity (''P''<0.05) and coupling control (''P''<0.05) were significantly lower than sham. These data highlight a differential response in muscle mitochondrial function to burn trauma, where the timing, degree and mode of dysfunction are dependent on whether the muscle is local or distal to the burn wound. on whether the muscle is local or distal to the burn wound.)
Krischek 2016 Mol Reprod Dev + (Altering incubation temperature during emb … Altering incubation temperature during embryogenesis has an impact on chicken embryo growth, but the underlying molecular mechanisms are not understood; the present study was performed to address these changes. Broiler eggs were incubated at low (36.8°C), control (37.8°C), and high (38.8°C) temperatures between Embryonic Day (ED) 7 and 10 or ED 10 and 13, which cover critical periods of embryonic myogenesis. The embryos were then dissected immediately after treatment on ED 10 or 13 to assess body, liver, and heart weights as well as to analyze breast and leg muscle fibers for their mitochondrial respiratory activity (MRA). Breast muscle samples were additionally used to evaluate the activity of enzymes involved in energy metabolism and cell-cycle progression. ED-10 embryos incubated at 38.8°C showed elevated weights (body, liver, and heart), MRA, and activities of lactate dehydrogenase and cytochrome oxidase compared to the ED-10 embryos incubated at 36.8°C. Similarly, the ED-13 embryos incubated at 38.8°C showed elevated body weight, MRA, and activities of glycogen phosphorylase, phosphofructokinase, and cytochrome oxidase compared to their 36.8°C counterparts. Embryos incubated at the normal temperature (37.8°C), however, showed variable differences from those incubated at 38.8°C versus 36.8°C. Cell-cycle enzyme activities were not impacted by the different temperature treatments. Thus, an increase or decrease in the incubation temperature during embryonic broiler myogenesis results in altered embryo activity, muscle energy metabolism, and activity-dependent muscle growth.ism, and activity-dependent muscle growth.)
Oparka 2014 Abstract MiP2014 + (Alternations of pivotal mitochondrial func … Alternations of pivotal mitochondrial function – oxidative phosphorylation as well as abnormal cellular ROS production - can potentially be responsible for pathogenesis of cancer. In the last years, implications of p66Shc adaptor protein in the cellular response to oxidative stress have been discovered. Involvement of this protein in cell death is related to oxidative stress. Phosphorylation of p66Shc at Ser36 can be activated by extracellular or intracellular reactive oxygen species (ROS), and an initiated cascade of events is finally involved in the amplification of mitochondrial ROS production. The available literature does not contain a lot of data concerning the role of p66shc and its Ser36 phosphorylation in tumorigenesis and cancer growth. Therefore, we studied the relationship between ROS production, antioxidant defense systems and the level of p66Shc as well as p66Shc phosphorylation in murine cancer cell lines, derived from ectoderm (B16-F10, B78, MmB16, EMT6, 4T1), mesoderm (Renca) and endoderm (CT26.WT, Hepa1-6, LLC, Panc02).The cancer cells exhibited various levels of p66Shc and its Ser36 phosphorylation, which simultaneously is negatively correlated with the level of superoxide dismutase 2 in some of the investigated cancer cell lines. ROS can mediate opposing cellular functions like cell proliferation and apoptosis. In turn, p66Shc Ser36 phosphorylation pathway is involved in regulation of mitochondrial metabolism and is responsible for elevated intracellular ROS levels. Moreover, p66Shc seems to play an important role in cancer metastasis and cancer cell adhesion. This emphasizes the importance of understanding the mechanisms and sites of ROS formation in cancer cells, the role of p66Shc in this process and the effect on tumor physiology.Supported by Statutory Founding from Nencki Institute of Experimental Biology and Polish Ministry of Science and Higher Education grant W100/HFSC/2011.and Higher Education grant W100/HFSC/2011.)
Polajnar 2014 PLOS ONE + (Alternative functions, apart from cathepsi … Alternative functions, apart from cathepsins inhibition, are being discovered for stefin B. Here, we investigate its role in vesicular trafficking and autophagy. Astrocytes isolated from stefin B knock-out (KO) mice exhibited an increased level of protein aggregates scattered throughout the cytoplasm. Addition of stefin B monomers or small oligomers to the cell medium reverted this phenotype, as imaged by confocal microscopy. To monitor the identity of proteins embedded within aggregates in wild type (wt) and KO cells, the insoluble cell lysate fractions were isolated and analyzed by mass spectrometry. Chaperones, tubulins, dyneins, and proteosomal components were detected in the insoluble fraction of wt cells but not in KO aggregates. In contrast, the insoluble fraction of KO cells exhibited increased levels of apolipoprotein E, fibronectin, clusterin, major prion protein, and serpins H1 and I2 and some proteins of lysosomal origin, such as cathepsin D and CD63, relative to wt astrocytes. Analysis of autophagy activity demonstrated that this pathway was less functional in KO astrocytes. In addition, synthetic dosage lethality (SDL) gene interactions analysis in ''Saccharomyces cerevisiae'' expressing human stefin B suggests a role in transport of vesicles and vacuoles These activities would contribute, directly or indirectly to completion of autophagy in wt astrocytes and would account for the accumulation of protein aggregates in KO cells, since autophagy is a key pathway for the clearance of intracellular protein aggregates.rance of intracellular protein aggregates.)
Rajendran 2019 EMBO Mol Med + (Alternative oxidase (AOX) is a non-mammali … Alternative oxidase (AOX) is a non-mammalian enzyme that can bypass blockade of the complex III-IV segment of the respiratory chain (RC). We crossed a Ciona intestinalis AOX transgene into RC complex III (cIII)-deficient Bcs1lp.S78G knock-in mice, displaying multiple visceral manifestations and premature death. The homozygotes expressing AOX were viable, and their median survival was extended from 210 to 590 days due to permanent prevention of lethal cardiomyopathy. AOX also prevented renal tubular atrophy and cerebral astrogliosis, but not liver disease, growth restriction, or lipodystrophy, suggesting distinct tissue-specific pathogenetic mechanisms. Assessment of reactive oxygen species (ROS) production and damage suggested that ROS were not instrumental in the rescue. Cardiac mitochondrial ultrastructure, mitochondrial respiration, and pathological transcriptome and metabolome alterations were essentially normalized by AOX, showing that the restored electron flow upstream of cIII was sufficient to prevent cardiac energetic crisis and detrimental decompensation. These findings demonstrate the value of AOX, both as a mechanistic tool and a potential therapeutic strategy, for cIII deficiencies.© 2018 The Authors. Published under the terms of the CC BY 4.0 license. Published under the terms of the CC BY 4.0 license.)
Robertson 2016 J Bioenerg Biomembr + (Alternative oxidase (AOX) is a terminal ox … Alternative oxidase (AOX) is a terminal oxidase within the inner mitochondrial membrane (IMM) present in many organisms where it functions in the electron transport system (ET-pathway). AOX directly accepts electrons from ubiquinol and is therefore capable of bypassing ET-pathway Complexes III and IV. The human genome does not contain a gene coding for AOX, so AOX expression has been suggested as a gene therapy for a range of human mitochondrial diseases caused by genetic mutations that render Complex III and/or IV dysfunctional. An effective means of screening mutations amenable to AOX treatment remains to be devised. We have generated such a tool by heterologously expressing AOX from the Pacific oyster (''Crassostrea gigas'') in the yeast ''Saccharomyces cerevisiae'' under the control of a galactose promoter. Our results show that this animal AOX is monomeric and is correctly targeted to yeast mitochondria. Moreover, when expressed in yeast, Pacific oyster AOX is a functional quinol oxidase, conferring cyanide-resistant growth and myxothiazol-resistant oxygen consumption to yeast cells and isolated mitochondria. This system represents a high-throughput screening tool for determining which Complex III and IV genetic mutations in yeast will be amenable to AOX gene therapy. As many human genes are orthologous to those found in yeast, our invention represents an efficient and cost-effective way to evaluate viable research avenues. In addition, this system provides the opportunity to learn more about the localization, structure, and regulation of AOXs from animals that are not easily reared or manipulated in the lab.t easily reared or manipulated in the lab.)
McDonald 2011 Abstract IOC65 + (Alternative oxidase (AOX) is a ubiquinol t … Alternative oxidase (AOX) is a ubiquinol terminal oxidase present in the respiratory electron transport chains of a wide variety of organisms [1]. AOX by-passes 2 of the 3 proton pumping complexes in the respiratory chain and therefore makes respiration less efficient in terms of the amount of ATP generated per oxygen consumed. Our previous work using bioinformatics has revealed the presence of AOX genes in eukaryotic organisms such as plants, animals, fungi, algae, and protists, as well as in prokaryotes in several species of eubacteria [2]. Recent work using reverse transcriptase polymerase chain reaction (RT-PCR) experiments has demonstrated that these genes are transcribed in many organisms [3]. Our focus is now shifting to exploring the respiratory capacity of AOX proteins in these different systems and in identifying how the activity of AOX proteins is regulated at the post-translational level.regulated at the post-translational level.)
Dogan 2018 Cell Metab + (Alternative oxidases (AOXs) bypass respira … Alternative oxidases (AOXs) bypass respiratory complexes III and IV by transferring electrons from coenzyme Q directly to O2. They have therefore been proposed as a potential therapeutic tool for mitochondrial diseases. We crossed the severely myopathic skeletal muscle-specific COX15 knockout (KO) mouse with an AOX-transgenic mouse. Surprisingly, the double KO-AOX mutants had decreased lifespan and a substantial worsening of the myopathy compared with KO alone. Decreased ROS production in KO-AOX versus KO mice led to impaired AMPK/PGC-1α signaling and PAX7/MYOD-dependent muscle regeneration, blunting compensatory responses. Importantly, the antioxidant N-acetylcysteine had a similar effect, decreasing the lifespan of KO mice. Our findings have major implications for understanding pathogenic mechanisms in mitochondrial diseases and for the design of therapies, highlighting the benefits of ROS signaling and the potential hazards of antioxidant treatment.ng and the potential hazards of antioxidant treatment.)
Moreno-Ortega 2016 Neurotox Res + (Alternatives for the treatment of amyotrop … Alternatives for the treatment of amyotrophic lateral sclerosis (ALS) are scarce and controversial. The etiology of neuronal vulnerability in ALS is being studied in motor neuron-like NSC-34 cells to determine the underlying mechanisms leading to selective loss of motor neurons. One such mechanism is associated with mitochondrial oxidative stress, Ca2+ overload, and low expression of Ca2+-buffering proteins. Therefore, in order to elicit neuronal death in ALS, NSC-34 cells were exposed to the following cytotoxic agents: (1) a mixture of oligomycin 10 µM and rotenone 30 µM (O/R), or (2) phenylarsine oxide 1 µM (PAO) (to mimic excess free radical production during mitochondrial dysfunction), and (3) veratridine 100 µM (VTD) (to induce overload of Na(+) and Ca2+ and to alter distribution of Ca2+-buffering proteins [parvalbumin and calbindin-D28k]). Thus, the aim of the study was to test the novel neuroprotective compound ITH33/IQM9.21 (ITH33) and to compare it with riluzole on ''in vitro'' models of neurotoxicity. Cell viability measured with MTT showed that only ITH33 protected against O/R at 3 μM and PAO at 10 μM, but not riluzole. ITH33 and riluzole were neuroprotective against VTD, blocked the maximum peak and the number of [Ca2+]c oscillations per cell, and restored the effect on parvalbumin. However, only riluzole reversed the effect on calbindin-D28k levels. Therefore, ITH33 was neuroprotective against oxidative stress and Na+/Ca2+ overload, both of which are involved in ALS.ainst oxidative stress and Na+/Ca2+ overload, both of which are involved in ALS.)
Irving 2022 Abstract Bioblast + (Although Alzheimer's disease (AD)'s underl … Although Alzheimer's disease (AD)'s underlying pathophysiology is incompletely understood, reductions in mitochondrial bioenergetics are observed during AD development. Reductions in nitric oxide (NO) bioavailability can reduce cerebral blood flow, promote the deposition of β-amyloid (Aβ), and contribute to mitochondrial dysfunction. However, pathological elevations in NO can also inhibit mitochondrial respiration and mitochondrial quality control. High-Fat Diets (HFD) are associated with reductions in NO bioavailability and AD development. Therefore, we sought to investigate the effects of dietary NO donors (Na+-nitrite and citrulline) on mitochondrial bioenergetics in female APPswe/PS1dE9 (APP/PS1) fed a HFD.We fed 10-week-old APP/PS1 transgenic mice, and their littermate controls (wild-type, WT) either a normal chow diet, HFD, or HFD supplemented with a NO promoter (Na+-nitrite or L-citrulline) for six months. Specifically, 100 mg/L Na+-nitrite or 2.5 mM L-citrulline was provided in their drinking water. The mice were euthanized, and the hypothalami were carefully dissected out and placed in ice-cold BIOPS. The hypothalami were homogenized in a mitochondrial respiration media (MiR05-Kit, pH 7.1).We used high-resolution respirometry (HRR, Oroboros O2k) coupled with a standardized substrate-uncoupler-inhibitor-titration (SUIT) protocol to measure respiration rates in duplicate during LEAK (State 4), OXPHOS capacity (State 3), and electron transfer capacity (ET) states in permeabilized hypothalami homogenates at 37 °C and O2 concentrations between ~450 µM and ~150 µM. We supplement the MiR05 with α-chaconine (40 µM) to chemically permeabilize the plasma membranes and synaptosomes. First, we measured NADH-linked LEAK respiration (N''L'') in the presence of pyruvate (5 mM), malate (2 mM), and glutamate (10 mM) in the absence of ADP. We measured NADH-Linked OXPHOS (N''P'') following the addition of a saturating concentration of ADP-Mg++ (5 mM). Next, we assessed the mitochondrial membrane integrity using cytochrome ''c'' (10 µM). We measured NS-linked OXPHOS (NS''P'') after the addition of succinate (10 mM). Next, we titrated in carbonyl cyanide m-chlorophenyl hydrazine (CCCP) (0.5 µM/step) to achieve NS-linked ET capacity (NS''E''). Next, we titrated rotenone (0.5 µM) to measure succinate-linked ET capacity (S''E''), followed by the titration of glycerol-3-phosphate (15 mM) to measure SGp-linked ET capacity (SGp''E''). Finally, we added antimycin A (2.5 µM) to measure residual oxygen consumption (''Rox''). The respiration rates were normalized per mg mass [pmol·s-1·mg-1], referred to as oxygen flux (''J''O2).The final body and fat masses of HFD-fed APP/PS1 mice (48.2 g & 17.7 g) were significantly higher than those of HFD-fed WT mice (42.4 g & 14.3 g). NO donors (Na+-nitrite or citrulline) had no effect on body mass or fat mass. There was a significant group effect (''p''<0.05) effect on OXPHOS and ET capacity. Specifically, the APS/PS1 mice had significantly lower OXPHOS and ET capacity while on the HFD compared to WT. The NO donors (Na+-nitrite or citrulline) could rescue the OXPHOS and ET capacity in the APS/PS1 mice fed a HFD.In summary, the APS/PS1 mice had lower OXPHOS and ET capacity than their WT controls while on an HFD. Physiologically relevant NO donors may provide an opportunity to mitigate some of the negative consequences of AD pathology.n the APS/PS1 mice fed a HFD. In summary, the APS/PS1 mice had lower OXPHOS and ET capacity than their WT controls while on an HFD. Physiologically relevant NO donors may provide an opportunity to mitigate some of the negative consequences of AD pathology.)
Khrameeva 2014 Nat Commun + (Although Neanderthals are extinct, fragmen … Although Neanderthals are extinct, fragments of their genomes persist in contemporary humans. Here we show that while the genome-wide frequency of Neanderthal-like sites is approximately constant across all contemporary out-of-Africa populations, genes involved in lipid catabolism contain more than threefold excess of such sites in contemporary humans of European descent. Evolutionally, these genes show significant association with signatures of recent positive selection in the contemporary European, but not Asian or African populations. Functionally, the excess of Neanderthal-like sites in lipid catabolism genes can be linked with a greater divergence of lipid concentrations and enzyme expression levels within this pathway, seen in contemporary Europeans, but not in the other populations. We conclude that sequence variants that evolved in Neanderthals may have given a selective advantage to anatomically modern humans that settled in the same geographical areas.at settled in the same geographical areas.)
Gnecchi-Ruscone 2018 Genome Biol Evol + (Although Tibetans and Sherpa present sever … Although Tibetans and Sherpa present several physiological adjustments evolved to cope with selective pressures imposed by the high altitude environment, especially hypobaric hypoxia, few selective sweeps at a limited number of hypoxia related genes were confirmed by multiple genomic studies. Nevertheless, variants at these loci were found to be associated only with downregulation of the erythropoietic cascade, which represents an indirect aspect of the considered adaptive phenotype. Accordingly, the genetic basis of Tibetan/Sherpa adaptive traits remains to be fully elucidated, in part due to limitations of selection scans implemented so far and mostly relying on the hard sweep model.In order to overcome this issue, we used whole genome sequence data and several selection statistics as input for gene network analyses aimed at testing for the occurrence of polygenic adaptation in these high-altitude Himalayan populations. Being able to detect also subtle genomic signatures ascribable to weak positive selection at multiple genes of the same functional subnetwork, this approach allowed us to infer adaptive evolution at loci individually showing small effect sizes, but belonging to highly interconnected biological pathways overall involved in angiogenetic processes.Therefore, these findings pinpointed a series of selective events neglected so far, which likely contributed to the augmented tissue blood perfusion observed in Tibetans and Sherpa, thus uncovering the genetic determinants of a key biological mechanism that underlies their adaptation to high altitude.derlies their adaptation to high altitude.)
Becker 1999 Am J Physiol + (Although a burst of oxidants has been well … Although a burst of oxidants has been well described with reperfusion, less is known about the oxidants generated by the highly reduced redox state and low O(2) of ischemia. This study aimed to further identify the species and source of these oxidants. Cardiomyocytes were exposed to 1 h of simulated ischemia while oxidant generation was assessed by intracellular dihydroethidine (DHE) oxidation. Ischemia increased DHE oxidation significantly (0.7 +/- 0.1 to 2.3 +/- 0.3) after 1 h. Myxothiazol (mitochondrial site III inhibitor) attenuated oxidation to 1.3 +/- 0.1, as did the site I inhibitors rotenone (1.0 +/- 0.1), amytal (1.1 +/- 0.1), and the flavoprotein oxidase inhibitor diphenyleneiodonium (0.9 +/- 0.1). By contrast, the site IV inhibitor cyanide, as well as inhibitors of xanthine oxidase (allopurinol), nitric oxide synthase (nitro-L-arginine methyl ester), and NADPH oxidase (apocynin), had no effect. Finally, DHE oxidation increased with Cu- and Zn-containing superoxide dismutase (SOD) inhibition using diethyldithiocarbamate (2.7 +/- 0.1) and decreased with exogenous SOD (1.1 +/- 0.1). We conclude that significant superoxide generation occurs during ischemia before reperfusion from the ubisemiquinone site of the mitochondrial electron transport chain.he mitochondrial electron transport chain.)
Kilbaugh 2015 J Am Heart Assoc + (Although advances in cardiopulmonary resus … Although advances in cardiopulmonary resuscitation have improved survival from cardiac arrest (CA), neurologic injury persists and impaired mitochondrial bioenergetics may be critical for targeted neuroresuscitation. The authors sought to determine if excellent cardiopulmonary resuscitation and postresuscitation care and good traditional survival rates result in persistently disordered cerebral mitochondrial bioenergetics in a porcine pediatric model of asphyxia-associated ventricular fibrillation CA.After 7 minutes of asphyxia, followed by ventricular fibrillation, 5 female 1-month-old swine (4 sham) received blood pressure-targeted care: titration of compression depth to systolic blood pressure of 90 mm Hg and vasopressor administration to a coronary perfusion pressure >20 mm Hg. All animals received protocol-based vasopressor support after return of spontaneous circulation for 4 hours before they were killed. The primary outcome was integrated mitochondrial electron transport system (ET-pathway) function. CA animals displayed significantly decreased maximal, coupled oxidative phosphorylating respiration (OXPHOSCI + CII) in cortex (P<0.02) and hippocampus (P<0.02), as well as decreased phosphorylation and coupling efficiency (cortex, P<0.05; hippocampus, P<0.05). Complex I- and complex II-driven respiration were both significantly decreased after CA (cortex: OXPHOSCI P<0.01, ETSCII P<0.05; hippocampus: OXPHOSCI P<0.03, ETSCII P<0.01). In the hippocampus, there was a significant decrease in maximal uncoupled, nonphosphorylating respiration (ETSCI + CII), as well as a 30% reduction in citrate synthase activity (P<0.04).Mitochondria in both the cortex and hippocampus displayed significant alterations in respiratory function after CA despite excellent cardiopulmonary resuscitation and postresuscitation care in asphyxia-associated ventricular fibrillation CA. Analysis of integrated ET-pathway function identifies mitochondrial bioenergetic failure as a target for goal-directed neuroresuscitation after CA. IACUC Protocol: IAC 13-001023.oal-directed neuroresuscitation after CA. IACUC Protocol: IAC 13-001023.)
Spinelli 2018 Nat Cell Biol + (Although classically appreciated for their … Although classically appreciated for their role as the powerhouse of the cell, the metabolic functions of mitochondria reach far beyond bioenergetics. In this Review, we discuss how mitochondria catabolize nutrients for energy, generate biosynthetic precursors for macromolecules, compartmentalize metabolites for the maintenance of redox homeostasis and function as hubs for metabolic waste management. We address the importance of these roles in both normal physiology and in disease. in both normal physiology and in disease.)
Sanchez 2001 Br J Pharmacol + (Although cyclosporin (CsA) is considered t … Although cyclosporin (CsA) is considered to be the best immunosuppressive molecule in transplantation, it has been suspected to alter mitochondrial respiration of various tissues.We evaluated the acute effect of CsA and its vehicle on maximal oxidative capacity (Vmax) of cardiac, soleus and gastrocnemius muscles of rats by an oxygraphic method in saponin skinned muscle fibres. The effects of Sandimmun (a formulation of CsA), vehicle of Sandimmun (cremophor and ethanol (EtOH)), CsA in EtOH and EtOH alone were tested. Increasing concentrations (5 – 20 – 50 – 100 μM) of CsA (or vehicles) were used.Sandimmun profoundly altered the Vmax of all muscles. For example, at 20 μM, inhibition reached 18±3, 23±5, 45±5%, for heart, soleus and gastrocnemius respectively. There were only minor effects of CsA diluted in EtOH and EtOH alone on Vmax of cardiac muscle. Because the effects of vehicle on Vmax were similar or higher than those of Sandimmun, the inhibition of oxidative capacity could be entirely attributed to the vehicle for all muscles.Next, we investigated the potential sites of action of the vehicle on the different complexes of the mitochondrial respiratory chain by using specific substrates and inhibitors. The vehicle affected mitochondrial respiration mainly at the level of complex I (≈−85 % in skeletal muscles, and −32 % in heart), but also at complex IV (≈−26 % for all muscles).The mechanism of action of the vehicle on the mitochondrial membrane and the implications for the clinical use of immunosuppressive drugs are discussed. of immunosuppressive drugs are discussed.)
Belosludtsev 2019 Cells + (Although diabetes mellitus is known to be … Although diabetes mellitus is known to be a disease associated with mitochondrial dysfunction, not everything is clear about mitochondrial Ca2+ transport and Ca2+-induced permeability transition in diabetic cells. The objective of this work was to study the operation of MCU and Ca2+-dependent mitochondrial permeabilization in the liver cells of Sprague-Dawley rats under the streptozotocin-induced type I diabetes. It was shown that two weeks after the induction of diabetes, the rate of Ca2+ uptake by the mitochondria of diabetic animals increased ~1.4-fold. The expression of MCU and MICU1 subunits did not change, yet the quantity of dominant-negative MCUb channel subunits was almost twice as lower. The organelles also became more resistant to the induction of CsA-sensitive MPT pore and less resistant to the induction of CsA-insensitive palmitate/Ca2+-induced pore. The mitochondria of diabetic liver cells also showed changes in the lipid matrix of their membranes. The content of fatty acids in the membranes grew, and microviscosity of the lipid bilayer (assessed with laurdan) increased. At the same time, lipid peroxidation (assessed by the production of malonic dialdehyde) was stimulated. The paper discusses the consequences of the diabetes-related changes in mitochondria in the context of cell physiology.es the consequences of the diabetes-related changes in mitochondria in the context of cell physiology.)
Lee 2023 Antioxidants (Basel) + (Although elevated cholesterol and other re … Although elevated cholesterol and other recognised cardiovascular risk factors are important in the development of coronary artery disease (CAD) and heart attack, the susceptibility of humans to this fatal process is distinct from other animals. Mitochondrial dysfunction of cells in the arterial wall, particularly the endothelium, has been strongly implicated in the pathogenesis of CAD. In this manuscript, we review the established evidence and mechanisms in detail and explore the potential opportunities arising from analysing mitochondrial function in patient-derived cells such as endothelial colony-forming cells easily cultured from venous blood. We discuss how emerging technology and knowledge may allow us to measure mitochondrial dysfunction as a potential biomarker for diagnosis and risk management. We also discuss the "pros and cons" of animal models of atherosclerosis, and how patient-derived cell models may provide opportunities to develop novel therapies relevant for humans. Finally, we review several targets that potentially alleviate mitochondrial dysfunction working both via direct and indirect mechanisms and evaluate the effect of several classes of compounds in the cardiovascular context.f compounds in the cardiovascular context.)
Koncsos 2016 Am J Physiol Heart Circ Physiol + (Although incidence and prevalence of predi … Although incidence and prevalence of prediabetes are increasing, little is known about its cardiac effects. Therefore, our aim was to investigate the effect of prediabetes on cardiac function and to characterize parameters and pathways associated with deteriorated cardiac performance. Long-Evans rats were fed with either control or high-fat chow for 21 wk and treated with a single low dose (20 mg/kg) of streptozotocin at week 4 High-fat and streptozotocin treatment induced prediabetes as characterized by slightly elevated fasting blood glucose, impaired glucose and insulin tolerance, increased visceral adipose tissue and plasma leptin levels, as well as sensory neuropathy. In prediabetic animals, a mild diastolic dysfunction was observed, the number of myocardial lipid droplets increased, and left ventricular mass and wall thickness were elevated; however, no molecular sign of fibrosis or cardiac hypertrophy was shown. In prediabetes, production of reactive oxygen species was elevated in subsarcolemmal mitochondria. Expression of mitofusin-2 was increased, while the phosphorylation of phospholamban and expression of Bcl-2/adenovirus E1B 19-kDa protein-interacting protein 3 (BNIP3, a marker of mitophagy) decreased. However, expression of other markers of cardiac auto- and mitophagy, mitochondrial dynamics, inflammation, heat shock proteins, Ca2+/calmodulin-dependent protein kinase II, mammalian target of rapamycin, or apoptotic pathways were unchanged in prediabetes. This is the first comprehensive analysis of cardiac effects of prediabetes indicating that mild diastolic dysfunction and cardiac hypertrophy are multifactorial phenomena that are associated with early changes in mitophagy, cardiac lipid accumulation, and elevated oxidative stress and that prediabetes-induced oxidative stress originates from the subsarcolemmal mitochondria.tress originates from the subsarcolemmal mitochondria.)
Wang 2019 Free Radic Biol Med + (Although insulin-like growth factor-1 rece … Although insulin-like growth factor-1 receptor (IGF-1R) has been accepted as a major determinant of cancers, its biological roles and corresponding mechanisms in tumorigenesis have remained elusive. Herein, we demonstrate that IGF-1R plays pivotal roles in the regulation of mitochondrial respiratory chain and functions during colitis and tumorigenesis. Heterozygous knockout IGF-1R attenuated azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colitis and colitis associated cancer (CAC) in Igf1r+/- mice. Heterozygous knockout IGF-1R confers resistance to oxidative stress-induced damage on colorectal epithelial cells by protecting mitochondrial dynamics and structures. IGF-1R low expression improves the biological function of mitochondrial fusion under oxidative stress. Mechanically, an increase in respiratory coupling index (RCI) and oxidative phosphorylation index (ADP/O) was seen in colorectal epithelial cells of Igf1r+/- mice. Seahorse XFe-24 analyzer analysis of mitochondrial bioenergetics demonstrated an increase in oxygen consumption rate (OCR) and a decrease of extracellular acidification rate (ECAR) in Igf1r+/- cells. Further analysis suggests the protection mechanisms of Igf1r+/- cells from oxidative stress through the activation of the mitochondrial respiratory chain and LKB1/AMPK pathways. These results highlight the biological roles of IGF-1R at the nexus between oxidative damage and mitochondrial function and a connection between colitis and colorectal cancer.Copyright © 2019 Elsevier Inc. All rights reserved.een colitis and colorectal cancer. Copyright © 2019 Elsevier Inc. All rights reserved.)
Marchi 2014 J Physiol + (Although it has long been known that mitoc … Although it has long been known that mitochondria take up Ca2+, the molecular identities of the channels and transporters involved in this process were revealed only recently. Here, we discuss the recent work that has led to the characterization of the mitochondrial calcium uniporter complex, which includes the channel-forming subunit MCU (mitochondrial calcium uniporter) and its regulators MICU1, MICU2, MCUb, EMRE, MCUR1 and miR-25. We review not only the biochemical identities and structures of the proteins required for mitochondrial Ca2+ uptake but also their implications in different physiopathological contexts. in different physiopathological contexts.)
Cai 2021 Free Radic Biol Med + (Although it is well known that selective i … Although it is well known that selective intra-arterial cooling (SI-AC) elicits cerebral protection against ischemia/reperfusion (I/R) injury, the underlying mechanism remains unclear. This study aimed to determine whether SI-AC can protect against cerebral I/R injury by inhibiting oxidative stress and mitochondrial dysfunction through regulation of Sirt3 deSUMOylation via SENP1.All mice were subjected to 2 h of cerebral ischemia followed by 24 h of reperfusion. SI-AC treatment was performed by infusion with cold saline (10 °C, 20 mL/kg) for 15 min through a microcatheter placed in the internal carotid artery immediately before reperfusion. The infarct volume, survival rate, neurological deficit scores, behavioral parameters, histopathology findings, and apoptosis were assessed. HT22 cells were subjected to 2 h of oxygen and sugar deprivation (OGD) and 22 h of reoxygenation. HA-SUMO1, Flag-Sirt3, a Sirt3 mutation plasmid (Flag-Sirt3 K288R), His-SENP1, and SENP1 small interfering RNA were transfected into HT22 cells 48 h before OGD. Apoptosis-related proteins were analyzed by western blotting. SUMOylation of Sirt3, acetylation of cyclooxygenase 1 (COX1), superoxide dismutase 2 (SOD2), and isocitrate dehydrogenase 2 (IDH2), the activities of COX1, SOD2, and IDH2, oxidative stress, and mitochondrial dysfunction were evaluated.Compared with the I/R group, SI-AC decreased cerebral infarct volume and neurological deficit scores and increased motor coordination, exploratory behavior, and memory. Hematoxylin and eosin and Nissl staining showed that SI-CA decreased karyopyknosis, nuclear fragmentation, and nucleolysis, increased neuron density, and decreased the cell apoptosis rate. In addition, Sirt3 was revealed as a target protein of SUMO1. SI-AC attenuated cerebral I/R injury through Sirt3 deSUMOylation via SENP1.SENP1-mediated deSUMOylation of Sirt3 plays an essential role in SI-AC-induced cerebral protection against I/R injury. Our findings provide a promising therapeutic approach for treatment of acute cerebral I/R injury.or treatment of acute cerebral I/R injury.)
Xiao 2019 Int J Hypertens + (Although many researches regarding risk fa … Although many researches regarding risk factors for hypertension have been reported, little information is known about the effect of BMI on the prevalence of hypertension considering sex differences. The aim of this study was to examine the sex difference in the prevalence of hypertension with the predicting indicator BMI. A total number of 6330 subjects in Shaanxi were examined using multivariable logistic regression to study the relationship between genders in different levels of BMI and prevalence of hypertension. Overall, females had a higher prevalence of hypertension than males, being 28.36 % and 21.55 %, respectively. The mean of blood pressure and the prevalence of hypertension increased as BMI getting larger. The result of multivariable logistic regression showed that obese and overweight males had higher risk of getting hypertension than their female counterparts. Further prevention of hypertension should be focused on obese and overweight males more than females and examining the mechanism of how sex differences influence the prevalence of hypertension. influence the prevalence of hypertension.)
Hom 2011 Dev Cell + (Although mature myocytes rely on mitochond … Although mature myocytes rely on mitochondria as the primary source of energy, the role of mitochondria in the developing heart is not well known. Here, we find that closure of the mitochondrial permeability transition pore (mPTP) drives maturation of mitochondrial structure and function and myocyte differentiation. Cardiomyocytes at embryonic day (E) 9.5, when compared to E13.5, displayed fragmented mitochondria with few cristae, a less-polarized mitochondrial membrane potential, higher reactive oxygen species (ROS) levels, and an open mPTP. Pharmacologic and genetic closing of the mPTP yielded maturation of mitochondrial structure and function, lowered ROS, and increased myocyte differentiation (measured by counting Z bands). Furthermore, myocyte differentiation was inhibited and enhanced with oxidant and antioxidant treatment, respectively, suggesting that redox-signaling pathways lie downstream of mitochondria to regulate cardiac myocyte differentiation. regulate cardiac myocyte differentiation.)
Gupta 2021 Sci Rep + (Although microRNA-7 (miRNA-7) is known to … Although microRNA-7 (miRNA-7) is known to regulate proliferation of cancer cells by targeting Epidermal growth factor receptor (EGFR/ERBB) family, less is known about its role in cardiac physiology. Transgenic (Tg) mouse with cardiomyocyte-specific overexpression of miRNA-7 was generated to determine its role in cardiac physiology and pathology. Echocardiography on the miRNA-7 Tg mice showed cardiac dilation instead of age-associated physiological cardiac hypertrophy observed in non-Tg control mice. Subjecting miRNA-7 Tg mice to transverse aortic constriction (TAC) resulted in cardiac dilation associated with increased fibrosis bypassing the adaptive cardiac hypertrophic response to TAC. miRNA-7 expression in cardiomyocytes resulted in significant loss of ERBB2 expression with no changes in ERBB1 (EGFR). Cardiac proteomics in the miRNA-7 Tg mice showed significant reduction in mitochondrial membrane structural proteins compared to NTg reflecting role of miRNA-7 beyond the regulation of EGFR/ERRB in mediating cardiac dilation. Consistently, electron microscopy showed that miRNA-7 Tg hearts had disorganized rounded mitochondria that was associated with mitochondrial dysfunction. These findings show that expression of miRNA-7 in the cardiomyocytes results in cardiac dilation instead of adaptive hypertrophic response during aging or to TAC providing insights on yet to be understood role of miRNA-7 in cardiac function.stood role of miRNA-7 in cardiac function.)
Kamunde 2018 Free Radic Biol Med + (Although mitochondria are presumed to emit … Although mitochondria are presumed to emit and consume reactive oxygen species (ROS), the quantitative interplay between the two processes in ROS regulation is not well understood. Here, we probed the role of mitochondrial bioenergetics in H2O2 metabolism using rainbow trout liver and heart mitochondria. Both liver and heart mitochondria emitted H2O2 at rates that depended on their metabolic state, with the emission rates (free radical leak) constituting 0.8-2.9% and 0.2-2.5% of the respiration rate in liver and heart mitochondria, respectively. When presented with exogenous H2O2, liver and heart mitochondria consumed it by first order reactions with half-lives (s) of 117 and 210, and rate constants of 5.96 and 3.37 (× 10-3 s-1), respectively. The mitochondrial bioenergetic status greatly affected the rate of H2O2 consumption in heart but not liver mitochondria. Moreover, the activities and contribution of H2O2 scavenging systems varied between liver and heart mitochondria. The significance of the scavenging systems ranked by the magnitude (%) of inhibition of H2O2 removal after correcting for emission were, liver (un-energized and energized): catalase > glutathione (GSH) ≥ thioredoxin reductase (TrxR); un-energized heart mitochondria: catalase > TrxR > GSH and energized heart mitochondria: GSH > TrxR > catalase. Notably, depletion of GSH evoked a massive surge in H2O2 emission that grossly masked the contribution of this pathway to H2O2 scavenging in heart mitochondria. Irrespective of the organ of their origin, mitochondria behaved as H2O2 regulators that emitted or consumed it depending on the ambient H2O2 concentration, mitochondrial bioenergetic state and activity of the scavenging enzyme systems. Indeed, manipulation of mitochondrial bioenergetics and H2O2 scavenging systems caused mitochondria to switch from being net consumers to net emitters of H2O2. Overall, our data suggest that the low levels of H2O2 typically present in cells would favor emission of this metabolite but the scavenging systems would prevent its accumulation.cavenging systems caused mitochondria to switch from being net consumers to net emitters of H2O2. Overall, our data suggest that the low levels of H2O2 typically present in cells would favor emission of this metabolite but the scavenging systems would prevent its accumulation.)
MacDonald 2018 IOC130 + (Although mitochondria are presumed to emit … Although mitochondria are presumed to emit and consume reactive oxygen species (ROS), the quantitative interplay between the two processes in ROS regulation is not well understood. Here, we probed the role of mitochondrial bioenergetics in H2O2 metabolism using rainbow trout liver and heart mitochondria. Both liver and heart mitochondria emitted H2O2 at rates that depended on their metabolic state, with the emission rates (free radical leak) constituting 0.8 to 2.9% and 0.2 to 2.5% of the respiration rate in liver and heart mitochondria, respectively. When presented with exogenous H2O2, liver and heart mitochondria consumed it by first order reactions with half-lives (s) of 117 and 210, and rate constants of 5.96 and 3.37 (× 10-3 s-1), respectively. The mitochondrial bioenergetic status greatly affected the rate of H2O2 consumption in heart but not liver mitochondria. Moreover, the activities and contribution of H2O2 scavenging systems varied between liver and heart mitochondria. The significance of the scavenging systems ranked by the magnitude (%) of inhibition of H2O2 removal after correcting for emission were, liver (un-energized and energized): catalase > glutathione (GSH) ≥ thioredoxin reductase (TrxR); un-energized heart mitochondria: catalase > TrxR > GSH and energized heart mitochondria: GSH > TrxR > catalase. Notably, depletion of GSH evoked a massive surge in H2O2 emission that grossly masked the contribution of this pathway to H2O2 scavenging in heart mitochondria. Irrespective of the organ of their origin, mitochondria behaved as H2O2 regulators that emitted or consumed it depending on the ambient H2O2 concentration, mitochondrial bioenergetic state and activity of the scavenging enzyme systems. Indeed, manipulation of mitochondrial bioenergetics and H2O2 scavenging systems caused mitochondria to switch from being net consumers to net emitters of H2O2. Overall, our data suggest that the low levels of H2O2 typically present in cells would favor emission of this metabolite but the scavenging systems would prevent its accumulation.cavenging systems caused mitochondria to switch from being net consumers to net emitters of H2O2. Overall, our data suggest that the low levels of H2O2 typically present in cells would favor emission of this metabolite but the scavenging systems would prevent its accumulation.)
Jardim-Messeder 2022 Biochim Biophys Acta Bioenerg + (Although mitochondria have a central role … Although mitochondria have a central role in energy transduction and reactive oxygen species (ROS) production, the regulatory mechanisms and their involvement in plant stress signaling are not fully established. The phytohormone salicylic acid (SA) is an important regulator of mitochondria-mediated ROS production and defense signaling. The role of SA and adenine nucleotides in the regulation of the mitochondrial succinate dehydrogenase (SDH) complex activity and ROS production was analyzed using WT, RNAi SDH1-1 and disrupted stress response 1 (dsr1) mutants, which show a point mutation in SDH1 subunit and are defective in SA signaling. Our results showed that SA and adenine nucleotides regulate SDH complex activity by distinct patterns, contributing to increased SDH-derived ROS production. As previously demonstrated, SA induces the succinate-quinone reductase activity of SDH complex, acting at or near the ubiquinone binding site. On the other hand, here we demonstrated that adenine nucleotides, such as AMP, ADP and ATP, induce the SDH activity provided by the SDH1 subunit. The regulation of SDH activity by adenine nucleotides is dependent on mitochondrial integrity and is prevented by atractyloside, an inhibitor of adenine nucleotide translocator (ANT), suggesting that the regulatory mechanism occurs on the mitochondrial matrix side of the inner mitochondrial membrane, and not in the intermembrane space, as previously suggested. On the other hand, in the intermembrane space, ADP and ATP limit mitochondrial oxygen consumption by a mechanism that appears to be related to cytochrome bc1 complex inhibition. Altogether, these results indicate that SA signaling and adenine nucleotides regulate the mitochondrial electron transport system and mitochondria-derived ROS production by direct effect in the electron transport system complexes, bringing new insights into mechanisms with direct implications in plant development and responses to different environmental responses, serving as a starting point for future physiological explorations.int for future physiological explorations.)
Hervouet 2005 Carcinogenesis + (Although mitochondrial deficiency in cance … Although mitochondrial deficiency in cancer has been described by Warburg, many years ago, the mechanisms underlying this impairment remain essentially unknown. Many types of cancer cells are concerned and, in particular, clear cell renal carcinoma (CCRC). In this cancer, the tumor suppressor gene, VHL (von Hippel-Lindau factor) is invalidated. Previous studies have shown that the transfection of the VHL gene in VHL-deficient cells originating from CCRCs could suppress their ability to form tumors when they were injected into nude mice. However, various additional genetic alterations are observed in such cancer cells. In order to investigate whether VHL invalidation was related to the mitochondrial impairment, we have studied the effects of wild-type VHL transfection into VHL-deficient 786-0 or RCC10 cells on their oxidative phosphorylation (OXPHOS) subunit contents and functions. We show that the presence of wild-type VHL protein (pVHL) increased mitochondrial DNA and respiratory chain protein contents and permitted the cells to rely on their mitochondrial ATP production to grow in the absence of glucose. In parallel to mtDNA increase, the presence of pVHL up regulated the mitochondrial transcription factor A, as shown by western blot analysis. In conclusion, in CCRCs, pVHL deficiency is one of the factors responsible for down-regulation of the biogenesis of OXPHOS complexes.ion of the biogenesis of OXPHOS complexes.)
Kukat 2014 PLoS Genet + (Although mitochondrial dysfunction is ofte … Although mitochondrial dysfunction is often accompanied by excessive reactive oxygen species (ROS) production, we previously showed that an increase in random somatic mtDNA mutations does not result in increased oxidative stress. Normal levels of ROS and oxidative stress could also be a result of an active compensatory mechanism such as a mild increase in proton leak. Uncoupling protein 2 (UCP2) was proposed to play such a role in many physiological situations. However, we show that upregulation of UCP2 in mtDNA mutator mice is not associated with altered proton leak kinetics or ROS production, challenging the current view on the role of UCP2 in energy metabolism. Instead, our results argue that high UCP2 levels allow better utilization of fatty acid oxidation resulting in a beneficial effect on mitochondrial function in heart, postponing systemic lactic acidosis and resulting in longer lifespan in these mice. This study proposes a novel mechanism for an adaptive response to mitochondrial cardiomyopathy that links changes in metabolism to amelioration of respiratory chain deficiency and longer lifespan.tory chain deficiency and longer lifespan.)
Karamercan 2013 Shock + (Although mitochondrial dysfunction is thou … Although mitochondrial dysfunction is thought to contribute to the development of posttraumatic organ failure, current techniques to assess mitochondrial function in tissues are invasive and clinically impractical. We hypothesized that mitochondrial function in peripheral blood mononuclear cells (PBMCs) would reflect cellular respiration in other organs during hemorrhagic shock and resuscitation.Using a fixed-pressure HS model, Long-Evans rats were bled to a mean arterial pressure of 40 mmHg. When blood pressure could no longer be sustained without intermittent fluid infusion (decompensated HS), lactated Ringer's solution was incrementally infused to maintain the mean arterial pressure at 40 mmHg until 40% of the shed blood volume was returned (severe HS). Animals were then resuscitated with 4× total shed volume in lactated Ringer's solution over 60 min (resuscitation). Control animals underwent the same surgical procedures, but were not hemorrhaged. Animals were randomized to control (''n'' = 6), decompensated HS (''n'' = 6), severe HS (''n'' = 6), or resuscitation (''n'' = 6) groups. Kidney, liver, and heart tissues as well as PBMCs were harvested from animals in each group to measure mitochondrial oxygen consumption using high-resolution respirometry. Flow cytometry was used to assess mitochondrial membrane potential (Ψm) in PBMCs. One-way analysis of variance and Pearson correlations were performed.Mitochondrial oxygen consumption decreased in all tissues, including PBMCs, following decompensated HS, severe HS, and resuscitation. However, the degree of impairment varied significantly across tissues during hemorrhagic shock and resuscitation. Of the tissues investigated, PBMC mitochondrial oxygen consumption and Ψm provided the closest correlation to kidney mitochondrial function during HS (complex I: ''r'' = 0.65; complex II: ''r'' = 0.65; complex IV: ''r'' = 0.52; ''P'' < 0.05). This association, however, disappeared with resuscitation. A weaker association between PBMC and heart mitochondrial function was observed, but no association was noted between PBMC and liver mitochondrial function.All tissues including PBMCs demonstrated significant mitochondrial dysfunction following hemorrhagic shock and resuscitation. Although PBMC and kidney mitochondrial function correlated well during hemorrhagic shock, the variability in mitochondrial response across tissues over the spectrum of hemorrhagic shock and resuscitation limits the usefulness of using PBMCs as a proxy for tissue-specific cellular respiration.oxy for tissue-specific cellular respiration.)
Wang 2011 Mol Oncol + (Although mitochondrial respiration is decr … Although mitochondrial respiration is decreased in most cancer cells, the role of this decrease in carcinogenesis and cancer progression is still unclear. To better understand this phenomenon, instead of further inhibiting mitochondrial function, we induced mitochondrial biogenesis in transformed cells by activating the peroxisome proliferator-activated receptors (PPARs)/peroxisome proliferator-activated receptor gamma co-activator 1α [[PGC-1alpha|(PGC-1α)]] pathways. This was achieved by treating the cells with bezafibrate, a PPARs panagonist that also enhances [[PGC-1α]] expression. We confirmed that bezafibrate treatment led to increased mitochondrial proteins and enzyme functions. We found that cells with increased mitochondrial biogenesis had decreased growth rates in glucose-containing medium. In addition, they became less invasive, which was directly linked to the reduced lactate levels. Surprisingly, even though bezafibrate-treated cells had higher levels of mitochondrial markers, total respiration was not significantly altered. However, respiratory coupling, and ATP levels were. Our data show that by increasing the efficiency of the mitochondrial oxidative phosphorylation system, cancer progression is hampered by decreases in cell proliferation and invasiveness.es in cell proliferation and invasiveness.)
Hickey 2009 Am J Physiol Cell Physiol + (Although most attention has been focused o … Although most attention has been focused on mitochondrial ATP production and transfer in failing hearts, less has been focused on the nonfailing hypertensive heart. Here, energetic complications are less obvious, yet they may provide insight into disease ontogeny. We studied hearts from 12-mo-old spontaneously hypertensive rats (SHR) relative to normotensive Wistar-Kyoto (WKY) rats. The ex vivo working-heart model of SHR showed reduced compliance and impaired responses to increasing preloads. High-resolution respirometry showed higher state 3 (with excess ADP) respiration in SHR left ventricle fibers with complex I substrates and maximal uncoupled respiration with complex I + complex II substrates. Respiration with ATP was depressed 15% in SHR fibers relative to WKY fibers, suggesting impaired ATP hydrolysis. This finding was consistent with a 50% depression of actomyosin ATPase activities. Superoxide production from SHR fibers was similar to that from WKY fibers respiring with ADP; however, it was increased by 15% with ATP. In addition, the apparent ''K''m for ADP was 54% higher for SHR fibers, and assays conducted after ''ex vivo'' work showed a 28% depression of complex I in SHR, but not WKY, fibers. Transmission electron microscopy showed similar mitochondrial volumes but a decrease in the number of cristae in SHR mitochondria. Tissue lipid peroxidation was also 15% greater in SHR left ventricle. Overall, these data suggest that although cardiac mitochondria from nonfailing SHR hearts function marginally better than those from WKY hearts, they show dysfunction after intense work. Impaired ATP turnover in hard-working SHR hearts may starve cardiac mitochondria of ADP and elevate superoxide.ve cardiac mitochondria of ADP and elevate superoxide.)
Dejean 2001 Biochim Biophys Acta + (Although on-line calorimetry has been wide … Although on-line calorimetry has been widely used to detect transitions in global metabolic activity during the growth of microorganisms, the relationships between oxygen consumption flux and heat production are poorly documented. In this work, we developed a respirometric and calorimetric approach to determine the enthalpy efficiency of respiration-linked energy transformation of isolated yeast mitochondria and yeast cells under growing and resting conditions. On isolated mitochondria, the analysis of different phosphorylating and non-phosphorylating steady states clearly showed that the simultaneous measurements of heat production and oxygen consumption rates can lead to the determination of both the enthalpy efficiency and the ATP/O yield of oxidative phosphorylation. However, these determinations were made possible only when the net enthalpy change associated with the phosphorylating system was different from zero. On whole yeast cells, it is shown that the simultaneous steady state measurements of the heat production and oxygen consumption rates allow the enthalpy growth efficiency (i.e. the amount of energy conserved as biomass compared to the energy utilised for complete catabolism plus anabolism) to be assessed. This method is based on the comparison between the calorimetric-respirometric ratio (CR ratio) determined under growth versus resting conditions during a purely aerobic metabolism. Therefore, in contrast to the enthalpy balance approach, this method does not rely on the exhaustive and tedious determinations of the metabolites and elemental composition of biomass. Thus, experiments can be performed in the presence of non-limiting amounts of carbon substrate, an approach which has been successfully applied to slow growing cells such as yeast cells expressing wild-type or a mutant rat uncoupling protein-1.type or a mutant rat uncoupling protein-1.)
Ali 2014 Abstract MiP2014 + (Although originally defined as harmful byp … Although originally defined as harmful byproducts of aerobic metabolism, reactive oxygen species (ROS) are currently believed to play a critical role in downstream signaling, which regulates protein kinases, phosphatases, transcription factors and ion transport channels. However, mechanisms by which ROS is responsively produced, sensed and translated in cellular domains, especially neurons, remain elusive. Recently, NADPH oxidase (NOX), which is a multimeric enzyme that catalyzes the production of superoxide (O2•) from O2 and NADPH and was originally identified in neutrophils as essential for the host response respiratory burst, has been shown to localize in the brain. The unexpected presence of NOX in neurons has led to the idea that NOX-induced ROS are important in non-host defense contexts; e.g. intracellular and intercellular redox signaling. In previous works, we showed that NOX is actively producing O2• in the brain and might therefore be an important element that influences redox homeostasis in health, disease, and aging. Questions on specific connections between NOX activation and neuronal dysfunctions remain open for exploration by unconventional experimental approaches capable of probing the implications of in vivo NOX assembly and activation. Here, we studied oxygen-consuming, superoxide-producing NOX basal as well as induced activities in synaptosomes. Isolated synaptosomes (severed nerve terminals) are studied because they contain all necessary components of a functional neuronal environment including ion channels, receptors, and mitochondria. We demonstrate the ability of the Oroboros Oxygraph-2k, in parallel with spin-trapping/labeling electron paramagnetic resonance (EPR) techniques, to study sources and dynamics of ROS in synaptosomes. To the best of our knowledge, this is the first time that the Oroboros system has been employed to quantify NOX activity in synaptosomes. to quantify NOX activity in synaptosomes.)
Maddalena 2017 Biochem Biophys Res Commun + (Although oxygen levels in the extracellula … Although oxygen levels in the extracellular space of most mammalian tissues are just a few percent, under standard cell culture conditions they are not regulated and are often substantially higher. Some cellular sources of reactive oxygen species, like NADPH oxidase 4, are sensitive to oxygen levels in the range between 'normal' physiological (typically 1-5%) and standard cell culture (up to 18%). Hydrogen peroxide in particular participates in signal transduction pathways via protein redox modifications, so the potential increase in its production under standard cell culture conditions is important to understand. We measured the rates of cellular hydrogen peroxide production in some common cell lines, including C2C12, PC-3, HeLa, SH-SY5Y, MCF-7, and mouse embryonic fibroblasts (MEFs) maintained at 18% or 5% oxygen. In all instances the rate of hydrogen peroxide production by these cells was significantly greater at 18% oxygen than at 5%. The increase in hydrogen peroxide production at higher oxygen levels was either abolished or substantially reduced by treatment with GKT 137831, a selective inhibitor of NADPH oxidase subunits 1 and 4. These data indicate that oxygen levels experienced by cells in culture influence hydrogen peroxide production via NADPH oxidase 1/4, highlighting the importance of regulating oxygen levels in culture near physiological values. However, we measured pericellular oxygen levels adjacent to cell monolayers under a variety of conditions and with different cell lines and found that, particularly when growing at 5% incubator oxygen levels, pericellular oxygen was often lower and variable. Together, these observations indicate the importance, and difficulty, of regulating oxygen levels experienced by cells in culture.en levels experienced by cells in culture.)
Ponce 2019 Thesis + (Although pathological alterations in gene … Although pathological alterations in gene expression and mitochondria function in response to cardiac ischemia are well recognized, the mechanisms driving these changes are incompletely understood. Nuclear to mitochondrial communication regulating gene expression and mitochondrial function is a critical process following cardiac ischemic injury. Here we determine that cyclin C, a component of the transcriptional regulator, Mediator complex, directly regulates cardiac and mitochondrial function by modifying mitochondrial fission. We tested the hypothesis that cyclin C has a binary function as a transcriptional cofactor in the nucleus and acute regulation of cardiac energetics in ischemia by enhancing mitochondrial fission in the cytoplasm.In response to stress, cyclin C translocates to the cytoplasm enhancing mitochondria fission in part through interactions with Cdk1. Using cardiac specific cyclin C knockout and overexpression mouse models, we determined cyclin C regulates mitochondria morphology under basal and ischemic conditions ''in vivo''. Furthermore, pretreatment with a Cdk1 inhibitor followed by ischemia ''in vivo'' results in reduced mitochondrial fission. Together, our study reveals that cyclin C regulates both hypertrophic gene expression and mitochondrial fission providing new insights into the regulation of cardiac energy metabolism following acute ischemic injury.etabolism following acute ischemic injury.)
Chang 2016 Transl Res + (Although restoration of mitochondrial func … Although restoration of mitochondrial function in mitochondrial diseases through peptide-mediated allogeneic mitochondrial delivery (PMD) has been demonstrated ''in vitro'', the ''in vivo'' therapeutic efficacy of PMD in Parkinson's disease (PD) has yet to be determined. In this study, we compared the functionality of mitochondrial transfer with or without Pep-1 conjugation in neurotoxin (6-hydroxydopamine, 6-OHDA)-induced PC12 cells and PD rat models. We injected mitochondria into the medial forebrain bundle (MFB) of the PD rats after subjecting the nigrostriatal pathway to a unilateral 6-OHDA lesion for 21 days, and we verified the effectiveness of the mitochondrial graft in enhancing mitochondrial function in the soma of the substantia nigra (SN) neuron through mitochondrial transport dynamics in the nigrostriatal circuit. The result demonstrated that only PMD with allogeneic and xenogeneic sources significantly sustained mitochondrial function to resist the neurotoxin-induced oxidative stress and apoptotic death in the rat PC12 cells. The remaining cells exhibited a greater capability of neurite outgrowth. Furthermore, allogeneic and xenogeneic transplantation of peptide-labeled mitochondria after 3 months improved the locomotive activity in the PD rats. This increase was accompanied by a marked decrease in dopaminergic neuron loss in the substantia nigra pars compacta (SNc) and consistent enhancement of tyrosine hydroxylase-positive immunoreaction of dopaminergic neurons in the SNc and striatum. We also observed that in the SN dopaminergic neuron in the treated PD rats, mitochondrial complex I protein and mitochondrial dynamics were restored, thus ameliorating the oxidative DNA damage. Moreover, we determined signal translocation of graft allogeneic mitochondria from the MFB to the calbindin-positive SN neuron, which demonstrated the regulatory role of mitochondrial transport in alleviating 6-OHDA-induced degeneration of dopaminergic neurons.Copyright © 2016 Elsevier Inc. All rights reserved. © 2016 Elsevier Inc. All rights reserved.)
McFarlane 2017 Am J Physiol Regul Integr Comp Physiol + (Although seasonal modifications of brown a … Although seasonal modifications of brown adipose tissue (BAT) in hibernators are well documented, we know little about functional regulation of BAT in different phases of hibernation. In the 13-lined ground squirrel, liver mitochondrial respiration is suppressed by up to 70% during torpor. This suppression is reversed during arousal and interbout euthermia (IBE), and corresponds with patterns of maximal activities of electron transport system (ET-pathway) enzymes. Uncoupling of BAT mitochondria is controlled by free fatty acid release stimulated by sympathetic activation of adipocytes, so we hypothesized that further regulation at the level of the ET-pathway would be of little advantage. As predicted, maximal ET-pathway enzyme activities of isolated BAT mitochondria did not differ between torpor and IBE. In contrast to this pattern, respiration rates of mitochondria isolated from torpid individuals were suppressed by ~60% compared with rates from IBE individuals when measured at 37°C. At 10°C, however, mitochondrial respiration rates tended to be greater in torpor than IBE. As a result, the temperature sensitivity (Q10) of mitochondrial respiration was significantly lower in torpor (~1.4) than IBE (~2.4), perhaps facilitating energy savings during entrance into torpor and thermogenesis at low body temperatures. Despite the observed differences in isolated mitochondria, norepinephrine-stimulated respiration rates of isolated BAT adipocytes did not differ between torpor and IBE, perhaps because the adipocyte isolation requires lengthy incubation at 37°C, potentially reversing any changes that occur in torpor. Such changes may include remodeling of BAT mitochondrial membrane phospholipids, which could change ''in situ'' enzyme activities and temperature sensitivities.Copyright © 2017 the American Physiological Society.© 2017 the American Physiological Society.)
Menze 2013 Abstract MiP2013 + (Although severe water loss is often detrim … Although severe water loss is often detrimental to life, some exceptional animals have developed mechanisms to survive water loss to 0.02–0.05 g H2O/g dry mass (anhydrobiosis). How the structural and functional integrity of the mitochondrion is maintained during desiccation and rehydration is currently not understood. The brine shrimp Artemia franciscana serves as an important model organism for anhydrobiosis. Desiccation tolerance in this animal is correlated with the accumulation of large amounts of highly hydrophilic macromolecules termed Late Embryogenesis Abundant (LEA) proteins. Most LEA proteins are intrinsically disordered in solution and thought to stabilize other proteins and membranes during desiccation [1]. Two mitochondrial targeted LEA proteins, AfrLEA3m and AfLEA1.3, have been described in A. franciscana and may help to maintain the integrity and functionality of the organelle when water is scarce [2, 3]. In order to evaluate the impact of AfLEA1.3 on water-stress tolerance of mitochondria the protein was transgenically expressed in Kc167 cells from the desiccation intolerant fruit fly Drosophila melanogaster [4]. A protein construct composed of AfLEA1.3 and green fluorescent protein was found to accumulate within mitochondria. Expression of AfLEA1.3 in non-permeabilized cells reduced mitochondrial proton leak by 20-30% in presence and absence of hyperosmotic stress. Oxygen consumption of permeabilized cells in presence of mixed substrates and ADP was 18% less inhibited by increasing concentrations of NaCl in cells expressing AfLEA1.3 compared to control cells. Mitochondria isolated from wild-type and AfLEA1.3 expressing cells showed a high respiratory control ratio (RCR) of 11.3 ± 1.4. Oxygen consumption in presence of ADP and substrates that supply NADH to Complex I were significantly reduced after freezing and thawing and this reduction was significantly greater in mitochondria from control cells (RCR = 7.3 ± 1.0) than in cells expressing AfLEA1.3 (RCR = 10.1 ± 0.7, ''P''< 0.05). Expression of AfLEA1.3 improved functions of mitochondria from D. melanogaster in several models of water stress. Protection was observed at hydration states in which AfLEA1.3 most likely lacks extensive secondary structure and the protein was most likely intrinsically disordered. AfLEA1.3 thus can operate outside the classic structure function paradigm. However, the observed effects afforded by the hydrated AfLEA1.3 protein do not preclude even greater stabilization of biological structure and function in the dried state.al structure and function in the dried state.)
Stickle 1989 Biol Bull + (Although some species of fish, crustaceans … Although some species of fish, crustaceans, and molluscs may behaviorally avoid hypoxic masses of small size and limited duration, others cannot. In a series of crustaceans, tolerance of hypoxia over 28 days at 30 °C, decreases as follows: ''Eurypanopeus depressus'' (38 Torr = LC50) > ''Palaemonetes pugio'' > ''Rhithropanopeus harrisii'' > ''Penaeus aztecus'' > ''Callinectes sapidus' (121 Torr = LC50). ''Callinectes sapidus'' and ''E. depressus'' die during 12-h exposure to anoxia and their heat dissipation rates (quantified by microcalorimetry) are depressed in seawater at 25 % air saturation (normoxia) to only 32 and 47 % of their metabolic rate at normoxia. In contrast, starved ''Crassostrea virginica'' and ''Thais haemastoma'' are anoxia tolerant; their metabolic rates are depressed under anoxia to 75 % and 9 % of the normoxic rate. Hypoxia tolerance is greater at 20 °C than at 30 °C for ''Penaeus aztecus'' and ''Crassostrea virginica'', but no temperature effect on tolerance exists for ''Callinectes sapidus''. Hypoxia tolerance varies inversely with salinity for Penaeus aztecus at 20 ° and 30 °C and for ''Callinectes sapidus'' at 30 °C, but it varies directly with salinity at 20 °C in ''Callinectes sapidus''. Greater depression of metabolic rate occurs in molluscs during anoxia exposure (and is correlated with greater hypoxia tolerance) than occurs in ''Callinectes sapidus'' and ''Penaeus aztecus'', which are not anoxia tolerant. Heavy mortality probably occurs in young ''Callinectes sapidus'' and ''Penaeus aztecus'' and in stages of the life history when the organisms are incapable of avoiding hypoxic water masses.anisms are incapable of avoiding hypoxic water masses.)
Rhee 1999 Exp Mol Med + (Although superoxide anions (O2.-) and H2O2 … Although superoxide anions (O2.-) and H2O2 are generally considered to be toxic by-products of respiration, recent evidence suggests that the production of these reactive oxygen species (ROS) might be an integral component of membrane receptor signaling. In mammalian cells, a variety of extracellular stimuli have recently been shown to induce a transient increase in the intracellular concentration of ROS, and specific inhibition of the ROS generation resulted in a complete blockage of stimulant-dependent signaling. In the next few years, therefore, a flurry of research activity is expected in relation to the elucidation of ROS production in response to receptor stimulation, identification of ROS target molecules, and investigation of ROS elimination. The goal of this report is to review our current knowledge of ROS-regulated signal transduction and propose future directions.ransduction and propose future directions.)
Hawkins 1985 Mar Ecol Prog Ser + (Although sustained predominantly by nutrie … Although sustained predominantly by nutrients obtained directly from the environment, metabolic requirements for both gametogenesis and general maintenance in an open-shore population of the bivalve mollusc ''Mytilus edulis'' L. from southwest England were also 'subsidized' from substantial energy reserves accumulated during periods of somatic growth. Depletion of these reserves over late winter was associated with a greater sensitivity in the rate of oxidative metabolism to exogenous nutrient availability, diminished metabolic efficiencies with which absorbed ration was utilized, and an associated increase in the instantaneous maintenance requirements. Absorption rates, which were nevertheless minimal during winter, are suggested to be endogenously regulated in a manner more indicative of time-averaged than immediate optimization. It is proposed that such regulation may be especially adaptive within ''M. edulis'', a sedentary species that experiences pronounced annual cycles of food availability, and in which costs deriving from feeding and associated activities are shown to add as much as 38 % to standard metabolic demands.uch as 38 % to standard metabolic demands.)
Gray 1998 Nucleic Acids Res + (Although the collection of completely sequ … Although the collection of completely sequenced mitochondrial genomes is expanding rapidly, only recently has a phylogenetically broad representation of mtDNA sequences from protists (mostly unicellular eukaryotes) become available. This review surveys the 23 complete protist mtDNA sequences that have been determined to date, commenting on such aspects as mitochondrial genome structure, gene content, ribosomal RNA, introns, transfer RNAs and the genetic code and phylogenetic implications. We also illustrate the utility of a comparative genomics approach to gene identification by providing evidence that orfB in plant and protist mtDNAs is the homolog of atp8 , the gene in animal and fungal mtDNA that encodes subunit 8 of the F0portion of mitochondrial ATP synthase. Although several protist mtDNAs, like those of animals and most fungi, are seen to be highly derived, others appear to be have retained a number of features of the ancestral, proto-mitochondrial genome. Some of these ancestral features are also shared with plant mtDNA, although the latter have evidently expanded considerably in size, if not in gene content, in the course of evolution. Comparative analysis of protist mtDNAs is providing a new perspective on mtDNA evolution: how the original mitochondrial genome was organized, what genes it contained, and in what ways it must have changed in different eukaryotic phyla.ave changed in different eukaryotic phyla.)
Agrimi 2014 Abstract IOC 2014-04 Schroecken + (Although the decrease of pyruvate secretio … Although the decrease of pyruvate secretion by brewer’s yeasts during fermentation has long been desired in the alcohol beverage industry, rather little is known about the regulation of pyruvate accumulation. In this study, we have characterized a previously developed a pyruvate undersecreting sake yeast obtained by isolating a strain (TCR7) tolerant to ethyl α-transcyanocinnamate, an inhibitor of pyruvate transport into mitochondria. To obtain insights into pyruvate metabolism, we investigated the mitochondrial activity of TCR7 by oxigraphy and 13C-metabolic flux analysis during aerobic growth . While mitochondrial pyruvate oxidation was higher, glycerol production was decreased in TCR7 compared to the reference. These results indicate that mitochondrial activity is elevated in the TCR7 strain with the consequence of decreased pyruvate accumulation. Surprisingly mitochondrial activity is much higher in the sake yeast compared to CEN.PK 113-7D, the reference strain in metabolic engineering. When shifted from aerobic to anaerobic conditions, sake yeast retains a branched mitochondrial structure for a longer time than laboratory strains. The regulation of mitochondrial activity can become a completely novel approach to manipulate metabolic profile during fermentation of brewer’s yeasts.[[File:Abstract Agrimi G Graphical.jpg|center|450px]]e:Abstract Agrimi G Graphical.jpg|center|450px]])
Pardee 1948 J Biol Chem + (Although the inhibition of succinic dehydr … Although the inhibition of succinic dehydrogenase by oxalacetate is a generally accepted fact, there is a paucity of data on the subject. In 1937Das (l), using a modified Thunberg technique, reported that the enzyme was 50 per cent inhibited by 2 X 1O-5 M oxalacetate when the succinateconcentration was 0.025 M. In 1939 Potter (2) reported that the oxidation of succinate by liver and kidney homogenates was inhibited bycozymase (DPN). Keilin and Hartree (3) and Mann and Quastel (4) attributed this effect, no doubt correctly, to the formation of oxalacetate,although no data on the effect of oxalacetate were presented. The inhibitory effect of DPN upon the succinate system was later studied bySwingle, Axelrod, and Elvehjem (5) who also determined the effect of oxalacetate upon the succinic dehydrogenase system by measuring oxygenuptake. They reported that at succinate concentrations of 0.045 M oxalacetate produced 98, 65, and 22 per cent inhibition at concentrations of50, 10, and 5 X 10e5 M. From the data given it is not possible to tell whether the inhibition was transitory, as will be shown below, or whetherthe experiments were of such short duration that the decreased inhibition was not revealed. Since we found that the inhibition declined with time,it is clear that the earlier experiments (1,5) cannot be accepted as quantitative measures of the inhibition by oxalacetate. They do, however, establish the fact that this substance has a remarkable affinity for the succinic enzyme; remarkable because it appears to be at least 1000 times greater than the affinity of the normal substrate for the enzyme, and because oxalacetate has been assumed to be formed in the course of succinate oxidation. If the physiologically formed oxalacetate were as toxic to succinate oxidation as added oxalacetate, the inhibition would have profound regulatory effects upon oxidative metabolism. Such does not seem to be the case, however, although the reasons are as yet obscure....hough the reasons are as yet obscure. ...)
Tartaro 2015 Transplant Proc + (Although the intermittent Pringle maneuver … Although the intermittent Pringle maneuver is used for major transplant surgery, traumas, and hepatic protection, long ischemia time and reperfusion may limit some protection in Wistar rats. The aim of the study was to evaluate the protection effects of intermittent clamping in the total hepatic pedicle after a long period of ischemia and reperfusion in Wistar rats.Forty-two male Wistar rats, weighing ± 327.7 g, were anesthetized intravenously with sodium thiopental and given a U-shaped incision in the abdomen. The total hepatic pedicle was isolated and subjected to clamping with a microvascular clamp. Groups included were the continuous group (CG, n = 14, 40 minutes of ischemia/40 minutes of reperfusion); the intermittent group (IG, n = 14, 4 cycles a 10 minute ischemia/reperfusion 10 minutes); and the sham group (SG, n = 14, 80 minutes of observation time). Blood collection for transaminase dosage was carried out, and hepatic biopsy specimens were taken for mitochondrial respiration and histological evaluation.In groups CG and IG, aspartate aminotransferase and alanine aminotransferase enzymes were elevated in comparison to group SG (P < .008); mitochondrias, when stimulated by use of adenosine diphosphate or carbonylcyanide p-trifluoromethoxyphenylhydrazone, had a significant decrease in mitochondrial respiration (P < .05), and the respiratory control ratio in the ischemic groups was lower (P < .03) when compared with the GS. On histological examination, 100% of the GC had lesions: 33% focal hemorrhagic necrosis, 17% sinuzoidal congestion and/or vacuolization, and 50% venous congestion; in the IG, 100% had lesions: 43% sinusoidal congestion and/or vacuolization and 57% venous congestion.The intermittent total hepatic pedicle clamping for a long period of time in the Wistar rats had no efficacy in protection of liver injury.Copyright © 2015 Elsevier Inc. All rights reserved.pyright © 2015 Elsevier Inc. All rights reserved.)
Ocloo 2017 J Appl Pharmac Sc + (Although the molluscicidal activity of cru … Although the molluscicidal activity of crude dichloromethane extract of ''Millettia thonningii'', known to be rich in alpinumisoflavones was attributed to its inhibition of isolated rat liver mitochondrial complex I activity, the effects of the constituent alpinuisoflavones on mitochondrial function have not been reported. The present study, therefore investigated the effect of O, O-dimethyl-alpinumisoflavone, a constituent of the crude dichloromethane extract of ''M. thonningii'' seeds and 4'-O-methyl-alpinumsioflavone, a naturally occurring alpinumisoflavone in ''Lonchocarpus glabrescens'' in isolated rat liver mitochondria and permeabilised mouse heart fibers using substrate-inhibitor titrations. The O, O-dimethyl-alpinumisoflavone inhibited State 3 respirations supported by glutamate/malate (complex I), succinate (complex II) and Ascorbate/TMPD (complex IV) in the permeabilised cardiac tissues but inhibited only the State 3 respiration supported by glutamate (complex I) in the isolated rat liver mitochondria. The 4'-O-methyl-alpinumsioflavone on the other hand inhibited State 3 respirations supported by all the substrates in both the isolated rat liver mitochondria and the permeabilised cardiac tissues. Thus, whilst O, O-dimethyl-alpinumisoflavone, a naturally occurring phyto-compound in the extract of ''M. thonningii'' seeds inhibits mitochondrial respiratory chain activity essentially at complex I, its derivative 4'-O-methyl-alpinumisoflavone, a naturally occurring phytocompound in ''Lonchocarpus glabrescens'' inhibits mitochondrial respiratory complexes I, II and IV.ndrial respiratory complexes I, II and IV.)
Tesori 2015 Sci Rep + (Although the only effective drug against p … Although the only effective drug against primary hepatocarcinoma, the multikinase inhibitor Sorafenib (SFB) usually fails to eradicate liver cancer. Since SFB targets mitochondria, cell metabolic reprogramming may underlie intrinsic tumor resistance. To characterize cancer cell metabolic response to SFB, we measured oxygen consumption, generation of reactive oxygen species (ROS) and ATP content in rat LCSC (Liver Cancer Stem Cells) -2 cells exposed to the drug. Genome wide analysis of gene expression was performed by Affymetrix technology. SFB cytotoxicity was evaluated by multiple assays in the presence or absence of metabolic inhibitors, or in cells genetically depleted of mitochondria. We found that low concentrations (2.5-5 μM) of SFB had a relatively modest effect on LCSC-2 or 293 T cell growth, but damaged mitochondria and increased intracellular ROS. Gene expression profiling of SFB-treated cells was consistent with a shift toward aerobic glycolysis and, accordingly, SFB cytotoxicity was dramatically increased by glucose withdrawal or the glycolytic inhibitor 2-DG. Under metabolic stress, activation of the AMP dependent Protein Kinase (AMPK), but not ROS blockade, protected cells from death. We conclude that mitochondrial damage and ROS drive cell killing by SFB, while glycolytic cell reprogramming may represent a resistance strategy potentially targetable by combination therapies.ially targetable by combination therapies.)
Tapia 2015 Crit Care + (Although the prognostic value of persisten … Although the prognostic value of persistent hyperlactatemia in septic shock is unequivocal, its physiological determinants are controversial. Particularly, the role of impaired hepatic clearance has been underestimated and is only considered relevant in patients with liver ischemia or cirrhosis. Our objectives were to establish whether endotoxemia impairs whole body net lactate clearance, and to explore a potential role for total liver hypoperfusion during the early phase of septic shock.After anesthesia, 12 sheep were subjected to hemodynamic/perfusion monitoring including hepatic and portal catheterization, and a hepatic ultrasound flow probe. After stabilization (point A), sheep were alternatively assigned to lipopolysaccharide (LPS) (5 mcg/kg bolus followed by 4 mcg/kg/h) or sham for a three-hour study period. After 60 minutes of shock, animals were fluid resuscitated to normalize mean arterial pressure. Repeated series of measurements were performed immediately after fluid resuscitation (point B), and one (point C) and two hours later (point D). Monitoring included systemic and regional hemodynamics, blood gases and lactate measurements, and ''ex-vivo'' hepatic mitochondrial respiration at point D. Parallel exogenous lactate and sorbitol clearances were performed at points B and D. Both groups included an intravenous bolus followed by serial blood sampling to draw a curve using the least squares method.Significant hyperlactatemia was already present in LPS as compared to sham animals at point B (4.7 (3.1 to 6.7) versus 1.8 (1.5 to 3.7) mmol/L), increasing to 10.2 (7.8 to 12.3) mmol/L at point D. A significant increase in portal and hepatic lactate levels in LPS animals was also observed. No within-group difference in hepatic DO2, VO2 or O2 extraction, total hepatic blood flow (point D: 915 (773 to 1,046) versus 655 (593 to 1,175) ml/min), mitochondrial respiration, liver enzymes or sorbitol clearance was found. However, there was a highly significant decrease in lactate clearance in LPS animals (point B: 46 (30 to 180) versus 1,212 (743 to 2,116) ml/min, P <0.01; point D: 113 (65 to 322) versus 944 (363 to 1,235) ml/min, P <0.01).Endotoxemia induces an early and severe impairment in lactate clearance that is not related to total liver hypoperfusion.re impairment in lactate clearance that is not related to total liver hypoperfusion.)
Boveris 1999 Methods Enzymol + (Although the regulation of mitochondrial r … Although the regulation of mitochondrial respiration and energy production in mammalian tissues has been exhaustively studied and extensively reviewed, a clear understanding of the regulation of cellular respiration has not yet been achieved. In particular, the role of tissue pO2 as a factor regulatingcellular respiration remains controversial. The concept of a complex and multisite regulation of cellular respiration and energy production signaled bycellular and intercellular messengers has evolved in the last few years and isstill being researched. A recent concept that regulation of cellular respirationis regulated by ADP, O2 and NO preserves the notion that energy demandsdrive respiration but places the kinetic control of both respiration and energysupply in the availability of ADP to F1-ATPase and of O2 and NO to cytochromeoxidase. In addition, recent research indicates that NO participates inredox reactions in the mitochondrial matrix that regulate the intramitochondrialsteady state concentration of NO itself and other reactive species such assuperoxide radical (O2−) and peroxynitrite (ONOO−). In this way, NO acquiresan essential role as a mitochondrial regulatory metabolite. NO exhibits a richbiochemistry and a high reactivity and plays an important role as intercellularmessenger in diverse physiological processes, such as regulation of blood flow,neurotransmission, platelet aggregation and immune cytotoxic response.aggregation and immune cytotoxic response.)
Meszaros 2014 Abstract MiP2014 + (Although the renaissance of functional mit … Although the renaissance of functional mitochondrial studies targets many tissues and organs, small intestinal mitochondria are less frequently examined. Nevertheless, the integrity of small intestinal mucosa is potentially threatened in various local and systemic pathologies, such as ischemia-reperfusion, septic shock or inflammatory bowel diseases. Mitochondrial dysfunction is critically involved in the pathomechanism of these diseases. Furthermore, timely restitution of adequate mitochondrial function can be a key step towards potentially effective therapeutic strategies.Our goal was to provide firm experimental data for functional mitochondrial investigations, and as a first step, we aimed to test and validate the available methods used for isolation of small intestinal mitochondria in rodents [1,2]. Whole thickness small intestinal mucosal samples of rats and guinea pigs were used, and mitochondria were isolated according to published protocols using chelating agents and differential centrifugation. The assessment of the functional state of isolated mitochondria was performed by means of high-resolution respirometry (Oroboros Oxygraph-2k). The integrity of the outer mt-membrane was tested with cytochrome ''c'' addition and photometric assay for mitochondrial swelling, while membrane potential changes were monitored by safranin fluorescence measurements.In case of rat samples, low respiratory control rates and extremely high cytochrome ''c'' responses were found, and swelling of mitochondria indicated serious damage of the outer mt-membrane. In contrast, guinea pig mitochondria were presented with good respiratory control, low cytochrome ''c'' response and baseline swelling parameters.Based on high-resolution respirometry we conclude that using the accessible, published methodologies, only functionally impaired mitochondria can be isolated from the rat. However, high quantities of intact and well coupled mitochondria can be obtained from the guinea pig. These mitochondria are suitable for further focused studies. Further methodological investigations, possible modifications or even new protocols are needed in order to clarify the cause of this significant interspecies difference. this significant interspecies difference.)
Paumelle 2019 J Hepatol + (Although the role of inflammation to comba … Although the role of inflammation to combat infection is known, the contribution of metabolic changes in response to sepsis is poorly understood. Sepsis induces the release of lipid mediators, many of which activate nuclear receptors such as the peroxisome proliferator-activated receptor (PPAR)α, which controls both lipid metabolism and inflammation. However, the role of hepatic PPARα in the response to sepsis is unknown.Sepsis was induced by intraperitoneal injection of Escherichia coli in different models of cell-specific Pparα-deficiency and their controls. The systemic and hepatic metabolic response was analysed using biochemical, transcriptomic and functional assays. PPARα expression was analysed in livers from elective surgery and critically ill patients and correlated with hepatic gene expression and blood parameters RESULTS: Both whole body and non-hematopoietic Pparα-deficiency in mice decreased survival upon bacterial infection. Livers of septic Pparα-deficient mice displayed an impaired metabolic shift from glucose to lipid utilization resulting in more severe hypoglycemia, impaired induction of hyperketonemia and increased steatosis due to lower expression of genes involved in fatty acid catabolism and ketogenesis. Hepatocyte-specific deletion of PPARα impaired the metabolic response to sepsis and was sufficient to decrease survival upon bacterial infection. Hepatic PPARA expression was lower in critically ill patients and correlated positively with expression of lipid metabolism genes, but not with systemic inflammatory markers.Metabolic control by PPARα in hepatocytes plays a key role in the host defense to infection. Lay summary: As the main cause of death of critically ill patients, sepsis remains a major health issue lacking efficacious therapies. While current clinical literature suggests an important role for inflammation, metabolic aspects of sepsis have been mostly overlooked. Here, we show that mice with an impaired metabolic response, due to deficiency of the nuclear receptor PPARα in the liver, exhibit enhanced mortality upon bacterial infection despite a similar inflammatory response, suggesting that metabolic interventions may be a viable strategy for improving sepsis outcomes.Copyright © 2019. Published by Elsevier B.V.right © 2019. Published by Elsevier B.V.)
Richards 2014 Surg Obes Relat Dis + (Although the salutary effects of bariatric … Although the salutary effects of bariatric surgery as a treatment for excess weight and type 2 diabetes are established, there is scant evidence for effects on other contributors to cardiovascular diseases such as repair of endothelial dysfunction. This study evaluates outcomes of bariatric surgery on late outgrowth endothelial progenitor cells (LOEPCs), a cell phenotype essential for endothelial repair.Patients with a body mass index >35 kg/m(2) and type 2 diabetes were enrolled into either medical or bariatric surgical arms. Primary outcomes included analysis of isolated LOEPCs from peripheral blood for growth, function, and mitochondrial respiration. Plasma was used for metabolic profiling.Medical arm patients showed no improvement in any of the parameters tested. Bariatric surgical arm patients showed a 24% reduction in body mass index as early as 3 months postintervention and resolution of type 2 diabetes at 24 months postintervention (HbA1c 31% reduction; fasting glucose 29% reduction). Bariatric surgery increased the numbers of LOEPCs 8-fold and increased LOEPC network formation 3-fold at 24 months postintervention. The increased numbers and activity of LOEPCs in the bariatric surgical arm correlated with improvements in body mass index, insulin, and triglyceride levels only at 24 month postintervention. LOEPC mitochondrial respiration displayed a trend toward improvement compared with baseline as evidenced by an increase (36%) at 24 months in the bariatric arm.Bariatric surgery increases LOEPC levels and activity, which correlates with weight loss and improved metabolic profile at 24 months postintervention.abolic profile at 24 months postintervention.)
Layec 2016 Am J Physiol Endocrinol Metab + (Although theoretically sound, the accuracy … Although theoretically sound, the accuracy and precision of (31)P-magnetic resonance spectroscopy ((31)P-MRS) approaches to quantitatively estimate mitochondrial capacity are not well documented. Therefore, employing four differing models of respiratory control [linear, kinetic, and multipoint adenosine diphosphate (ADP) and phosphorylation potential], this study sought to determine the accuracy and precision of (31)P-MRS assessments of peak mitochondrial adenosine-triphosphate (ATP) synthesis rate utilizing directly measured peak respiration (State 3) in permeabilized skeletal muscle fibers. In 23 subjects of different fitness levels, (31)P-MRS during a 24-s maximal isometric knee extension and high-resolution respirometry in muscle fibers from the vastus lateralis was performed. Although significantly correlated with State 3 respiration (r = 0.72), both the linear (45 ± 13 mM/min) and phosphorylation potential (47 ± 16 mM/min) models grossly overestimated the calculated ''in vitro'' peak ATP synthesis rate (P < 0.05). Of the ADP models, the kinetic model was well correlated with State 3 respiration (r = 0.72, P < 0.05), but moderately overestimated ATP synthesis rate (P < 0.05), while the multipoint model, although being somewhat less well correlated with State 3 respiration (r = 0.55, P < 0.05), most accurately reflected peak ATP synthesis rate. Of note, the PCr recovery time constant (τ), a qualitative index of mitochondrial capacity, exhibited the strongest correlation with State 3 respiration (r = 0.80, P < 0.05). Therefore, this study reveals that each of the (31)P-MRS data analyses, including PCr τ, exhibit precision in terms of mitochondrial capacity. As only the multipoint ADP model did not overstimate the peak skeletal muscle mitochondrial ATP synthesis, the multipoint ADP model is the only quantitative approach to exhibit both accuracy and precision.titative approach to exhibit both accuracy and precision.)
Luo 2018 Proc Natl Acad Sci U S A + (Although there has been considerable debat … Although there has been considerable debate about whether paternal mitochondrial DNA (mtDNA) transmission may coexist with maternal transmission of mtDNA, it is generally believed that mitochondria and mtDNA are exclusively maternally inherited in humans. Here, we identified three unrelated multigeneration families with a high level of mtDNA heteroplasmy (ranging from 24 to 76%) in a total of 17 individuals. Heteroplasmy of mtDNA was independently examined by high-depth whole mtDNA sequencing analysis in our research laboratory and in two Clinical Laboratory Improvement Amendments and College of American Pathologists-accredited laboratories using multiple approaches. A comprehensive exploration of mtDNA segregation in these families shows biparental mtDNA transmission with an autosomal dominantlike inheritance mode. Our results suggest that, although the central dogma of maternal inheritance of mtDNA remains valid, there are some exceptional cases where paternal mtDNA could be passed to the offspring. Elucidating the molecular mechanism for this unusual mode of inheritance will provide new insights into how mtDNA is passed on from parent to offspring and may even lead to the development of new avenues for the therapeutic treatment for pathogenic mtDNA transmission.eatment for pathogenic mtDNA transmission.)
Driescher 2019 Heliyon + (Although there is evidence linking sugar-s … Although there is evidence linking sugar-sweetened beverage (SSB) intake with the development of cardio-metabolic diseases, the underlying mechanisms remain unclear. The current study therefore evaluated the effects of SSB consumption by establishing a unique in-house ''in vivo'' experimental model.Male Wistar rats were divided into two groups: a) one consuming a popular local SSB (SSB- Jive), and b) a control group (Control-water) for a period of three and six months (n = 6 per group), respectively. Rats were gavaged on a daily basis with an experimental dosage amounting to half a glass per day (in human terms) (SSB vs. water). Cardiac function was assessed at baseline (echocardiography) and following ''ex vivo'' ischemia-reperfusion of the isolated perfused working rat heart. Oral glucose tolerance tests and mitochondrial respiratory analyses were also performed. In addition, the role of non-oxidative glucose pathways (NOGPs), i.e. the polyol pathway, hexosamine biosynthetic pathway (HBP) and PKC were assessed.These data show that SSB intake: a) resulted in increased weight gain, but did not elicit major effects in terms of insulin resistance and cardiac function after three and six months, respectively; b) triggered myocardial NOGP activation after three months with a reversion after six months; and c) resulted in some impairment in mitochondrial respiratory capacity in response to fatty acid substrate supply after six months.SSB intake did not result in cardiac dysfunction or insulin resistance. However, early changes at the molecular level may increase risk in the longer term.evel may increase risk in the longer term.)
Acuña-Castroviejo 2011 Curr Top Med Chem + (Although two main hypotheses of mitochondr … Although two main hypotheses of mitochondrial origin have been proposed, i.e., the autogenous and the endosymbiotic, only the second is being seriously considered currently. The 'hydrogen hypothesis' invokes metabolic symbiosis as the driving force for a symbiotic association between an anaerobic, strictly hydrogen-dependent (the host) and an eubacterium (the symbiont) that was able to respire, but which generated molecular hydrogen as an end product of anaerobic metabolism. The resulting proto-eukaryotic cell would have acquired the essentials of eukaryotic energy metabolism, evolving not only aerobic respiration, but also the physiological cost of the oxygen consumption, i.e., generation of reactive oxygen species (ROS) and the associated oxidative damage. This is not the only price to pay for respiring oxygen: mitochondria possess nitric oxide (NO·) for regulatory purposes but, in some instances it may react with superoxide anion radical to produce the toxic reactive nitrogen species (RNS), i.e. peroxynitrite anion, and the subsequent nitrosative damage. New mitochondria contain their own genome with a modified genetic code that is highly conserved among mammals. The transcription of certain mitochondrial genes may depend on the redox potential of the mitochondrial membrane. Mitochondria are related to the life and death of cells. They are involved in energy production and conservation, having an uncoupling mechanism to produce heat instead of ATP, but they are also involved in programmed cell death. Increasing evidence suggest the participation of mitochondria in neurodegenerative and neuromuscular diseases involving alterations in both nuclear (nDNA) and mitochondrial (mtDNA) DNA. Melatonin is a known powerful antioxidant and anti-inflammatory and increasing experimental and clinical evidence shows its beneficial effects against oxidative/nitrosative stress status, including that involving mitochondrial dysfunction. This review summarizes the data and mechanisms of action of melatonin in relation to mitochondrial pathologies. in relation to mitochondrial pathologies.)
Vicentini 2019 Plant Physiol Biochem + (Aluminum (Al) toxicity has been recognized … Aluminum (Al) toxicity has been recognized to be a main limiting factor of crop productivity in acid soil. Al interacts with cell walls disrupting the functions of the plasma membrane and is associated with oxidative damage and mitochondrial dysfunction. ''Jatropha curcas'' L. (''J. curcas'') is a drought resistant plant, widely distributed around the world, with great economic and medicinal importance. Here we investigated the effects of Al on ''J. curcas'' mitochondrial function and cell viability, analyzing mitochondrial respiration, phenolic compounds, reducing sugars and cell viability in cultured ''J. curcas'' cells. The results showed that at 70 μM, Al limited mitochondrial respiration by inhibiting the alternative oxidase (AOX) pathway in the respiratory chain. An increased concentration of reducing sugars and reduced concentration of intracellular phenolic compounds was observed during respiratory inhibition. After inhibition, a time-dependent upregulation of AOX mRNA was observed followed by restoration of respiratory activity and reducing sugar concentrations. Cultured ''J. curcas'' cells were very resistant to Al-induced cell death. In addition, at 70 μM, Al also appeared as an inhibitor of cell wall invertase. In conclusion, Al tolerance in cultured ''J. curcas'' cells involves a inhibition of mitochondrial AOX pathway, which seems to start an oxidative burst to induce AOX upregulation, which in turn restores consumption of O2 and substrates. These data provide new insight into the signaling cascades that modulate the Al tolerance mechanism.Copyright © 2019 Elsevier Masson SAS. All rights reserved.ght © 2019 Elsevier Masson SAS. All rights reserved.)
Vicentini 2019 Plant Physiol Biochim + (Aluminum (Al) toxicity has been recognized … Aluminum (Al) toxicity has been recognized to be a main limiting factor of crop productivity in acid soil. Al interacts with cell walls disrupting the functions of the plasma membrane and is associated with oxidative damage and mitochondrial dysfunction. ''Jatropha curcas'' L. (J. curcas) is a drought resistant plant, widely distributed around the world, with great economic and medicinal importance. Here we investigated the effects of Al on ''J. curcas'' mitochondrial function and cell viability, analyzing mitochondrial respiration, phenolic compounds, reducing sugars and cell viability in cultured ''J. curcas'' cells. The results showed that at 70 μM, Al limited mitochondrial respiration by inhibiting the alternative oxidase (AOX) pathway in the respiratory chain. An increased concentration of reducing sugars and reduced concentration of intracellular phenolic compounds was observed during respiratory inhibition. After inhibition, a time-dependent upregulation of AOX mRNA was observed followed by restoration of respiratory activity and reducing sugar concentrations. Cultured ''J. curcas'' cells were very resistant to Al-induced cell death. In addition, at 70 μM, Al also appeared as an inhibitor of cell wall invertase. In conclusion, Al tolerance in cultured ''J. curcas'' cells involves a inhibition of mitochondrial AOX pathway, which seems to start an oxidative burst to induce AOX upregulation, which in turn restores consumption of O2 and substrates. These data provide new insight into the signaling cascades that modulate the Al tolerance mechanism. that modulate the Al tolerance mechanism.)
Stojakovic 2021 Commun Biol + (Alzheimer's Disease (AD) is a devastating … Alzheimer's Disease (AD) is a devastating neurodegenerative disorder without a cure. Here we show that mitochondrial respiratory chain complex I is an important small molecule druggable target in AD. Partial inhibition of complex I triggers the AMP-activated protein kinase-dependent signaling network leading to neuroprotection in symptomatic APP/PS1 female mice, a translational model of AD. Treatment of symptomatic APP/PS1 mice with complex I inhibitor improved energy homeostasis, synaptic activity, long-term potentiation, dendritic spine maturation, cognitive function and proteostasis, and reduced oxidative stress and inflammation in brain and periphery, ultimately blocking the ongoing neurodegeneration. Therapeutic efficacy ''in vivo'' was monitored using translational biomarkers FDG-PET, 31P NMR, and metabolomics. Cross-validation of the mouse and the human transcriptomic data from the NIH Accelerating Medicines Partnership-AD database demonstrated that pathways improved by the treatment in APP/PS1 mice, including the immune system response and neurotransmission, represent mechanisms essential for therapeutic efficacy in AD patients.l for therapeutic efficacy in AD patients.)
Lim 2010 Proteomics + (Alzheimer's disease (AD) and type 2 diabet … Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are leading causes of morbidity and mortality in the elderly. Both diseases are characterized by amyloid deposition in target tissues: aggregation of amylin in T2DM is associated with loss of insulin-secreting beta-cells, while amyloid beta (A beta) aggregation in AD brain is associated with neuronal loss. Here, we used quantitative iTRAQ proteomics as a discovery tool to show that both A beta and human amylin (HA) deregulate identical proteins, a quarter of which are mitochondrial, supporting the notion that mitochondrial dysfunction is a common target in these two amyloidoses. A functional validation revealed that mitochondrial complex IV activity was significantly reduced after treatment with either HA or A beta, as was mitochondrial respiration. In comparison, complex I activity was reduced only after treatment with HA. A beta and HA, but not the non-amyloidogenic rat amylin, induced significant increases in the generation of ROS. Co-incubation of HA and A beta did not produce an augmented effect in ROS production, again suggesting common toxicity mechanisms. In conclusion, our data suggest that A beta and HA both exert toxicity, at least in part, via mitochondrial dysfunction, thus restoring their function may be beneficial for both AD and T2DM.on may be beneficial for both AD and T2DM.)
Lim 2011 PloS One + (Alzheimer's disease (AD) is a conformation … Alzheimer's disease (AD) is a conformational disease that is characterized by amyloid-β (Aβ) deposition in the brain. Aβ exerts its toxicity in part by receptor-mediated interactions that cause down-stream protein misfolding and aggregation, as well as mitochondrial dysfunction. Recent reports indicate that Aβ may also interact directly with intracellular proteins such as the mitochondrial enzyme ABAD (Aβ binding alcohol dehydrogenase) in executing its toxic effects. Mitochondrial dysfunction occurs early in AD, and Aβ's toxicity is in part mediated by inhibition of ABAD as shown previously with an ABAD decoy peptide. Here, we employed AG18051, a novel small ABAD-specific compound inhibitor, to investigate the role of ABAD in Aβ toxicity. Using SH-SY5Y neuroblastoma cells, we found that AG18051 partially blocked the Aβ-ABAD interaction in a pull-down assay while it also prevented the Aβ42-induced down-regulation of ABAD activity, as measured by levels of estradiol, a known hormone and product of ABAD activity. Furthermore, AG18051 is protective against Aβ42 toxicity, as measured by LDH release and MTT absorbance. Specifically, AG18051 reduced Aβ42-induced impairment of mitochondrial respiration and oxidative stress as shown by reduced ROS (reactive oxygen species) levels. Guided by our previous finding of shared aspects of the toxicity of Aβ and human amylin (HA), with the latter forming aggregates in Type 2 diabetes mellitus (T2DM) pancreas, we determined whether AG18051 would also confer protection from HA toxicity. We found that the inhibitor conferred only partial protection from HA toxicity indicating distinct pathomechanisms of the two amyloidogenic agents. Taken together, our results present the inhibition of ABAD by compounds such as AG18051 as a promising therapeutic strategy for the prevention and treatment of AD, and suggest levels of estradiol as a suitable read-out.evels of estradiol as a suitable read-out.)
Onukwufor 2022 Antioxidants (Basel) + (Alzheimer's disease (AD) is a devastating … Alzheimer's disease (AD) is a devastating progressive neurodegenerative disease characterized by neuronal dysfunction, and decreased memory and cognitive function. Iron is critical for neuronal activity, neurotransmitter biosynthesis, and energy homeostasis. Iron accumulation occurs in AD and results in neuronal dysfunction through activation of multifactorial mechanisms. Mitochondria generate energy and iron is a key co-factor required for: (1) ATP production by the electron transport chain, (2) heme protein biosynthesis and (3) iron-sulfur cluster formation. Disruptions in iron homeostasis result in mitochondrial dysfunction and energetic failure. Ferroptosis, a non-apoptotic iron-dependent form of cell death mediated by uncontrolled accumulation of reactive oxygen species and lipid peroxidation, is associated with AD and other neurodegenerative diseases. AD pathogenesis is complex with multiple diverse interacting players including Aβ-plaque formation, phosphorylated tau, and redox stress. Unfortunately, clinical trials in AD based on targeting these canonical hallmarks have been largely unsuccessful. Here, we review evidence linking iron dysregulation to AD and the potential for targeting ferroptosis as a therapeutic intervention for AD.osis as a therapeutic intervention for AD.)
De Godoy 2018 J Biol Chem + (Alzheimer's disease (AD) is a disabling an … Alzheimer's disease (AD) is a disabling and highly prevalent neurodegenerative condition, for which there are no effective therapies. Soluble oligomers of the amyloid-β peptide (AβOs) are thought to be proximal neurotoxins involved in early neuronal oxidative stress and synapse damage, ultimately leading to neurodegeneration and memory impairment in AD. The aim of the current study was to evaluate the neuroprotective potential of mesenchymal stem cells (MSCs) against the deleterious impact of AβOs on hippocampal neurons. To this end, we established transwell cocultures of rat hippocampal neurons and MSCs. We show that MSCs and MSC-derived extracellular vesicles protect neurons against AβO-induced oxidative stress and synapse damage, revealed by loss of pre- and postsynaptic markers. Protection by MSCs entails three complementary mechanisms: 1) internalization and degradation of AβOs; 2) release of extracellular vesicles containing active catalase; and 3) selective secretion of interleukin-6, interleukin-10, and vascular endothelial growth factor to the medium. Results support the notion that MSCs may represent a promising alternative for cell-based therapies in AD.lternative for cell-based therapies in AD.)
Martins 2017 Thesis + (Alzheimer's disease (AD) is a neurological … Alzheimer's disease (AD) is a neurological disorder that affects a large part of the world's population. It is characterized by memory loss, progressive dementia, behavioral changes and inability to perform routine activities. Histopathologically, AD presents the formation of plaques by the aggregation of amyloid-β peptides (Aβ) and neurofibrillary tangles, due to hyperphosphorylation of tau protein. The aim of this study was to investigate alterations in gene and protein expression related to AD and to evaluate the mechanisms involved in initial events of Aβ1-40 peptide toxicity after intracerebroventricular (i.c.v.) infusion. In addition, it was evaluated whether pre-treatment with atorvastatin prevents the toxic effects of this peptide. Adult male Swiss albino mice (3 months / 40-50g) were treated with atorvastatin 10 mg / kg / day, orally, or vehicle (0.9% saline) for 7 days. On the seventh day the aggregate form of Aβ1-40 (i.c.v., 400pmol / site) or saline was administered. After 24h, the animals were euthanized for biochemical analysis. The results show that atorvastatin is able to prevent the gene expression reduction of the postsynaptic protein PSD-95, the NMDA receptor GluN1 subunit and glutamatergic transporters GLAST and GLT-1 induced by Aβ1-40 infusion in the hippocampus. Aβ promoted a decrease in BDNF expression and an increase in reactive oxygen (ROS) and nitrogen (RNS) species levels. Pretreatment with atorvastatin was able to prevent the increased ROS and RNS. Through the evaluation of mitochondrial functionality by high resolution respirometry, we observed that Aβ1-40 did not significantly alter parameters of oxygen consumption. However, atorvastatin increased the mitochondrial respiratory capacity assessed in hippocampal homogenates. In conclusion, we observed that Aβ1-40 toxicity presents as initial events changes in proteins related to glutamatergic neurotransmission and oxidative stress. Atorvastatin prevents initial oxidative stress and increases mitochondrial respiratory capacity by an as yet unknown action mechanism, requiring further studies.s mitochondrial respiratory capacity by an as yet unknown action mechanism, requiring further studies.)
Rhein 2009 Proc Natl Acad Sci U S A + (Alzheimer's disease (AD) is characterized … Alzheimer's disease (AD) is characterized by amyloid-beta (Abeta)-containing plaques, neurofibrillary tangles, and neuron and synapse loss. Tangle formation has been reproduced in P301L tau transgenic pR5 mice, whereas APPswPS2N141I double-transgenic APP152 mice develop Abeta plaques. Cross-breeding generates triple transgenic (tripleAD) mice that combine both pathologies in one model. To determine functional consequences of the combined Abeta and tau pathologies, we performed a proteomic analysis followed by functional validation. Specifically, we obtained vesicular preparations from tripleAD mice, the parental strains, and nontransgenic mice, followed by the quantitative mass-tag labeling proteomic technique iTRAQ and mass spectrometry. Within 1,275 quantified proteins, we found a massive deregulation of 24 proteins, of which one-third were mitochondrial proteins mainly related to complexes I and IV of the oxidative phosphorylation system (OXPHOS). Notably, deregulation of complex I was tau dependent, whereas deregulation of complex IV was Abeta dependent, both at the protein and activity levels. Synergistic effects of Abeta and tau were evident in 8-month-old tripleAD mice as only they showed a reduction of the mitochondrial membrane potential at this early age. At the age of 12 months, the strongest defects on OXPHOS, synthesis of ATP, and reactive oxygen species were exhibited in the tripleAD mice, again emphasizing synergistic, age-associated effects of Abeta and tau in perishing mitochondria. Our study establishes a molecular link between Abeta and tau protein in AD pathology in vivo, illustrating the potential of quantitative proteomics.link between Abeta and tau protein in AD pathology in vivo, illustrating the potential of quantitative proteomics.)
Grimm 2016 Methods Mol Biol + (Alzheimer's disease (AD) is characterized … Alzheimer's disease (AD) is characterized by the presence of amyloid plaques (aggregates of amyloid-β [Aβ]) and neurofibrillary tangles (aggregates of tau) in the brain, but the underlying mechanisms of the disease are still partially unclear. A growing body of evidence supports mitochondrial dysfunction as a prominent and early, chronic oxidative stress-associated event that contributes to synaptic abnormalities, and, ultimately, selective neuronal degeneration in AD. Using a high-resolution respirometry system, we shed new light on the close interrelationship of this organelle with Aβ and tau in the pathogenic process underlying AD by showing a synergistic effect of these two hallmark proteins on the oxidative phosphorylation capacity of mitochondria isolated from the brain of transgenic AD mice. In the present chapter, we first introduce the principle of the Aβ and tau interaction on mitochondrial respiration, and secondly, we describe in detail the used respiratory protocol.e in detail the used respiratory protocol.)
Leuner 2012 Mol Neurobiol + (Alzheimer's disease (AD) is the most commo … Alzheimer's disease (AD) is the most common progressive neurodegenerative disease. Today, AD affects millions of people worldwide and the number of AD cases will increase with increased life expectancy. The AD brain is marked by severe neurodegeneration like the loss of synapses and neurons, atrophy and depletion of neurotransmitter systems in the hippocampus and cerebral cortex. Recent findings suggest that these pathological changes are causally induced by mitochondrial dysfunction and increased oxidative stress. These changes are not only observed in the brain of AD patients but also in the periphery. In this review, we discuss the potential role of elevated apoptosis, increased oxidative stress and especially mitochondrial dysfunction as peripheral markers for the detection of AD in blood cells especially in lymphocytes. We discuss recent not otherwise published findings on the level of complex activities of the respiratory chain comprising mitochondrial respiration and the mitochondrial membrane potential (MMP). We obtained decreased basal MMP levels in lymphocytes from AD patients as well as enhanced sensitivity to different complex inhibitors of the respiratory chain. These changes are in line with mitochondrial defects obtained in AD cell and animal models, and in post-mortem AD tissue. Importantly, these mitochondrial alterations where not only found in AD patients but also in patients with mild cognitive impairment (MCI). These new findings point to a relevance of mitochondrial function as an early peripheral marker for the detection of AD and MCI.al marker for the detection of AD and MCI.)
Djordjevic 2017 Neuroscience + (Alzheimer's disease (AD) is the most commo … Alzheimer's disease (AD) is the most common late onset neurodegenerative disorder with indications that women are disproportionately affected. Mitochondrial dysfunction has been one of the most discussed hypotheses associated with the early onset and progression of AD, and it has been attributed to intraneuronal accumulation of amyloid β (Aβ). It was suggested that one of the possible mediators for Aβ-impaired mitochondrial function is the nuclear factor kappa B (NF-κB) signaling pathway. NF-κB plays important roles in brain inflammation and antioxidant defense, as well as in the regulation of mitochondrial function, and studies have confirmed altered NF-κB signaling in AD brain. In this study, we looked for sex-based differences in impaired bioenergetic processes and NF-κB signaling in the AD-like brain using transgenic (Tg) CRND8 mice that express excessive brain Aβ, but without tau pathology. Our results show that mitochondrial dysfunction is not uniform in affected brain regions. We observed increased basal and coupled respiration in the hippocampus of TgCRND8 females only, along with a decreased Complex II-dependent respiratory activity. Cortical mitochondria from TgCRND8 mice have reduced uncoupled respiration capacity, regardless of sex. The pattern of changes in NF-κB signaling was the same in both brain structures, but was sex specific. Whereas in females there was an increase in all three subunits of NF-κB, in males we observed increase in p65 and p105, but no changes in p50 levels. These results demonstrate that mitochondrial function and inflammatory signaling in the AD-like brain is region- and sex-specific, which is an important consideration for therapeutic strategies. consideration for therapeutic strategies.)
Silaidos 2018 Biol Sex Differ + (Alzheimer's disease (AD) is the most commo … Alzheimer's disease (AD) is the most common form of dementia, and it affects more women than men. Mitochondrial dysfunction (MD) plays a key role in AD, and it is detectable at an early stage of the degenerative process in peripheral tissues, such as peripheral mononuclear blood cells (PBMCs). However, whether these changes are also reflected in cerebral energy metabolism and whether sex-specific differences in mitochondrial function occur are not clear. Therefore, we estimated the correlation between mitochondrial function in PBMCs and brain energy metabolites and examined sex-specific differences in healthy participants to elucidate these issues.The current pilot study included 9 male and 15 female healthy adults (mean age 30.8 ± 7.1 years). Respiration and activity of mitochondrial respiratory complexes were measured using a Clark-electrode (Oxygraph-2k system), and adenosine triphosphate (ATP) levels were determined using a bioluminescence-based assay in isolated PBMCs. Citrate synthase activity as a mitochondrial marker was measured using a photometric assay. Concentrations of brain energy metabolites were quantified in the same individuals using 1H-magnetic resonance spectroscopy (MRS).We detected sex-associated differences in mitochondrial function. Mitochondrial complexes I, I+II, and IV and uncoupled respiration and electron transport system (ETS) capacity in PBMCs isolated from blood samples of females were significantly (p < 0.05; p < 0.01) higher compared to males. ATP levels in the PBMCs of female participants were approximately 10% higher compared to males. Citrate synthase (CS) activity, a marker of mitochondrial content, was significantly (p < 0.05) higher in females compared to males. Sex-associated differences were also found for brain metabolites. The N-acetylaspartate (NAA) concentration was significantly higher in female participants compared to males in targeted regions. This difference was observed in white matter (WM) and an area with a high percentage (> 50%) of gray matter (GM) (p < 0.05; p < 0.01). The effect sizes indicated a strong influence of sex on these parameters. Sex-associated differences were found in PBMCs and brain, but the determined parameters were not significantly correlated.Our study revealed sex-associated differences in mitochondrial function in healthy participants. The underlying mechanisms must be elucidated in more detail, but our study suggests that mitochondrial function in PBMCs is a feasible surrogate marker to detect differences in mitochondrial function and energy metabolism in humans and it underscores the necessity of sex-specific approaches in therapies that target mitochondrial dysfunction.proaches in therapies that target mitochondrial dysfunction.)
Sharma 2021 Int J Mol Sci + (Alzheimer's disease (AD) is the most frequ … Alzheimer's disease (AD) is the most frequent cause of age-related neurodegeneration and cognitive impairment, and there are currently no broadly effective therapies. The underlying pathogenesis is complex, but a growing body of evidence implicates mitochondrial dysfunction as a common pathomechanism involved in many of the hallmark features of the AD brain, such as formation of amyloid-beta (Aβ) aggregates (amyloid plaques), neurofibrillary tangles, cholinergic system dysfunction, impaired synaptic transmission and plasticity, oxidative stress, and neuroinflammation, that lead to neurodegeneration and cognitive dysfunction. Indeed, mitochondrial dysfunction concomitant with progressive accumulation of mitochondrial Aβ is an early event in AD pathogenesis. Healthy mitochondria are critical for providing sufficient energy to maintain endogenous neuroprotective and reparative mechanisms, while disturbances in mitochondrial function, motility, fission, and fusion lead to neuronal malfunction and degeneration associated with excess free radical production and reduced intracellular calcium buffering. In addition, mitochondrial dysfunction can contribute to amyloid-β precursor protein (APP) expression and misprocessing to produce pathogenic fragments (e.g., Aβ1-40). Given this background, we present an overview of the importance of mitochondria for maintenance of neuronal function and how mitochondrial dysfunction acts as a driver of cognitive impairment in AD. Additionally, we provide a brief summary of possible treatments targeting mitochondrial dysfunction as therapeutic approaches for AD.function as therapeutic approaches for AD.)
Litwiniuk 2021 Pharmaceuticals (Basel) + (Alzheimer's disease and Parkinson's diseas … Alzheimer's disease and Parkinson's disease are the most common forms of neurodegenerative illnesses. It has been widely accepted that neuroinflammation is the key pathogenic mechanism in neurodegeneration. Both mitochondrial dysfunction and enhanced NLRP3 (nucleotide-binding oligomerization domain (NOD)-like receptor protein 3) inflammasome complex activity have a crucial role in inducing and sustaining neuroinflammation. In addition, mitochondrial-related inflammatory factors could drive the formation of inflammasome complexes, which are responsible for the activation, maturation, and release of pro-inflammatory cytokines, including interleukin-1β (IL-1β) and interleukin-18 (IL-18). The present review includes a broadened approach to the role of mitochondrial dysfunction resulting in abnormal NLRP3 activation in selected neurodegenerative diseases. Moreover, we also discuss the potential mitochondria-focused treatments that could influence the NLRP3 complex.ts that could influence the NLRP3 complex.)
Mezeiova 2020 Eur J Med Chem + (Alzheimer's disease is a progressive brain … Alzheimer's disease is a progressive brain disorder with characteristic symptoms and several pathological hallmarks. The concept of "one drug, one target" has not generated any new drugs since 2004. The new era of drug development in the field of AD builds upon rationally designed multi-target directed ligands that can better address the complexity of AD. Herewith, we designed ten novel derivatives of 2-propargylamino-naphthoquinone. The biological evaluation of these compounds includes inhibition of monoamine oxidase A/B, inhibition of amyloid-beta aggregation, radical-scavenging, and metal-chelating properties. Some of the compounds possess low cytotoxicity profile with an anti-inflammatory ability in the lipopolysaccharide-stimulated cellular model. All these features warrant their further testing in the field of AD. their further testing in the field of AD.)
Bobba 2015 Apoptosis + (Alzheimer’s disease (AD) and cancer procee … Alzheimer’s disease (AD) and cancer proceedvia one or more common molecular mechanisms: a metabolicshift from oxidative phosphorylation to glycolysis—corresponding to the activation of the Warburg effect—occurs in both diseases. The findings reported in this paperdemonstrate that, in the early phase of apoptosis, glucosemetabolism is enhanced, i.e. key proteins which internalizeand metabolize glucose—glucose transporter, hexokinaseand phosphofructokinase—are up-regulated, in concomitancewith a parallel decrease in oxygen consumption bymitochondria and increase of L-lactate accumulation.Reversal of the glycolytic phenotype occurs in the presenceof dichloroacetate, inhibitor of the pyruvate dehydrogenasekinase enzyme, which speeds up apoptosis of cerebellargranule cells, reawakening mitochondria and then modulatingglycolytic enzymes. Loss of the adaptive advantageafforded by aerobic glycolysis, which occurs in the latephase of apoptosis, exacerbates the pathological processesunderlying neurodegeneration, leading inevitably the cellto death. In conclusion, the data propose that both aerobic,i.e. Warburg effect, essentially due to the protectivenumbness of mitochondria, and anaerobic glycolysis, ratherdue to the mitochondrial impairment, characterize theentire time frame of apoptosis, from the early to the latephase, which mimics the development of AD.phase, which mimics the development of AD.)
Integrative Physiology of Exercise 2020 Virtual Event + (American Physiological Society’s (APS)Integrative Physiology of Exercise (IPE) 2020 conference, Virtual Event, 2020)
Petiz 2018 Chem Biol Interact + (Amidines are chemically characterized by t … Amidines are chemically characterized by the presence of two nitrogen atoms that bind to the same carbon atom in its structure. Several biological activities have been ascribed to these compounds. Pentamidine, an aromatic diamidine, is effective in the treatment against ''Pneumocystis carinii'' and leishmaniasis, but it can also have severe side effects. New amidine derivatives have been synthesized, among them N,N'-diphenyl-4-methoxy-benzamidine (methoxyamidine), which is effective against ''Leishmania amazonensis'' (LD50 = 20 μM) and ''Trypanosoma cruzi'' (LD50 = 59 nM). In the present study, methoxyamidine toxicity was evaluated in isolated rat liver mitochondria at the same range of concentrations that exert antiprotozoal activity. In these organelles, actively oxidizing glutamate + malate inhibited state 3 respiration (25 nmol mg-1 of protein) by ∼15%. The sites of inhibition in the respiratory chain were complex I and the segment between ubiquinone and complex III. Methoxyamidine also stimulated state 4 respiration by ∼32% and ∼43% at 50 and 65 nmol mg-1 of protein, respectively. Its uncoupling effect was confirmed by a dose-dependent increase in oxygen consumption in state 4 respiration that was induced by oligomycin, reaching up to ∼69% (65 nmol mg-1 of protein) and an increase in ATPase activity in intact mitochondria by ∼27% and ∼83% at 50 and 65 nmol mg-1 protein, respectively. Swelling that was supported by the oxidation of glutamate + malate in the presence of sodium acetate was reduced by methoxyamidine by ∼16% and 32% at 50 and 65 nmol mg-1 protein, respectively. Mitochondrial swelling in the absence of substrate and in the presence of K+ and valinomycin was inhibited by ∼20% at the same concentrations, suggesting that methoxyamidine affects mitochondrial membrane permeability and fluidity. Our data show that methoxyamidine has slight effects on the energy-linked functions of isolated mitochondria at concentrations that correspond to the LD50 against ''Leishmania amazonensis'' and ''Trypanosoma cruzi''. These findings may prompt further studies that evaluate methoxyamidine toxicity ''in vivo''.nst ''Leishmania amazonensis'' and ''Trypanosoma cruzi''. These findings may prompt further studies that evaluate methoxyamidine toxicity ''in vivo''.)
Hoefler 2016 Physiol Plant + (Amino acid catabolism is essential for adj … Amino acid catabolism is essential for adjusting pool sizes of free amino acids and takes part in energy production as well as nutrient remobilization. The carbon skeletons are generally converted to precursors or intermediates of the tricarboxylic acid cycle. In the case of cysteine, the reduced sulfur derived from the thiol group also has to be oxidized in order to prevent accumulation to toxic concentrations. Here we present a mitochondrial sulfur catabolic pathway catalyzing the complete oxidation of l-cysteine to pyruvate and thiosulfate. After transamination to 3-mercaptopyruvate, the sulfhydryl group from l-cysteine is transferred to glutathione by sulfurtransferase 1 and oxidized to sulfite by the sulfur dioxygenase ETHE1. Sulfite is then converted to thiosulfate by addition of a second persulfide group by sulfurtransferase 1. This pathway is most relevant during early embryo development and for vegetative growth under light-limiting conditions. Characterization of a double mutant produced from ''Arabidopsis thaliana'' T-DNA insertion lines for ETHE1 and sulfurtransferase 1 revealed that an intermediate of the ETHE1 dependent pathway, most likely a persulfide, interferes with amino acid catabolism and induces early senescence.© 2016 Scandinavian Plant Physiology Society.016 Scandinavian Plant Physiology Society.)
Girard 2018 mSphere + (Amino acids participate in several critica … Amino acids participate in several critical processes in the biology of trypanosomatids, such as osmoregulation, cell differentiation, and host cell invasion. Some of them provide reducing power for mitochondrial ATP synthesis. It was previously shown that alanine, which is formed mainly by the amination of pyruvate, is a metabolic end product formed when parasites are replicating in a medium rich in glucose and amino acids. It was shown as well that this amino acid can also be used for the regulation of cell volume and resistance to osmotic stress. In this work, we demonstrate that, despite it being an end product of its metabolism, ''Trypanosoma cruzi'' can take up and metabolize l-Ala through a low-specificity nonstereoselective active transport system. The uptake was dependent on the temperature in the range between 10 and 40°C, which allowed us to calculate an activation energy of 66.4 kJ/mol and estimate the number of transporters per cell at ~436,000. We show as well that, once taken up by the cells, l-Ala can be completely oxidized to CO2, supplying electrons to the electron transport chain, maintaining the electrochemical proton gradient across the mitochondrial inner membrane, and supporting ATP synthesis in ''T. cruzi'' epimastigotes. Our data demonstrate a dual role for Ala in the parasite's bioenergetics, by being a secreted end product of glucose catabolism and taken up as nutrient for oxidative mitochondrial metabolism.It is well known that trypanosomatids such as the etiological agent of Chagas' disease, ''Trypanosoma cruzi'', produce alanine as a main end product of their energy metabolism when they grow in a medium containing glucose and amino acids. In this work, we investigated if under starvation conditions (which happen during the parasite life cycle) the secreted alanine could be recovered from the extracellular medium and used as an energy source. Herein we show that indeed, in parasites submitted to metabolic stress, this metabolite can be taken up and used as an energy source for ATP synthesis, allowing the parasite to extend its survival under starvation conditions. The obtained results point to a dual role for Ala in the parasite's bioenergetics, by being a secreted end product of glucose catabolism and taken up as nutrient for oxidative mitochondrial metabolism.up as nutrient for oxidative mitochondrial metabolism.)
Guitart 2010 J Biol Chem + (Aminoacyl-tRNA synthetases (ARS) are modul … Aminoacyl-tRNA synthetases (ARS) are modular enzymes that aminoacylate transfer RNAs (tRNA) for their use by the ribosome during protein synthesis. ARS are essential and universal components of the genetic code that were almost completely established before the appearance of the last common ancestor of all living species. This long evolutionary history explains the growing number of functions being discovered for ARS, and for ARS homologues, beyond their canonical role in gene translation. Here we present a previously uncharacterized paralogue of seryl-tRNA synthetase named SLIMP (seryl-tRNA synthetase-like insect mitochondrial protein). SLIMP is the result of a duplication of a mitochondrial seryl-tRNA synthetase (SRS) gene that took place in early metazoans and was fixed in Insecta. Here we show that SLIMP is localized in the mitochondria, where it carries out an essential function that is unrelated to the aminoacylation of tRNA. The knockdown of SLIMP by RNA interference (RNAi) causes a decrease in respiration capacity and an increase in mitochondrial mass in the form of aberrant mitochondria.mass in the form of aberrant mitochondria.)
Kumar 2021 JCI Insight + (Ammonia is a cytotoxic metabolite with ple … Ammonia is a cytotoxic metabolite with pleiotropic molecular and metabolic effects, including senescence induction. During dysregulated ammonia metabolism, which occurs in chronic diseases, skeletal muscle becomes a major organ for nonhepatocyte ammonia uptake. Muscle ammonia disposal occurs in mitochondria via cataplerosis of critical intermediary metabolite α-ketoglutarate, a senescence-ameliorating molecule. Untargeted and mitochondrially targeted data were analyzed by multiomics approaches. These analyses were validated experimentally to dissect the specific mitochondrial oxidative defects and functional consequences, including senescence. Responses to ammonia lowering in myotubes and in hyperammonemic portacaval anastomosis rat muscle were studied. Whole-cell transcriptomics integrated with whole-cell, mitochondrial, and tissue proteomics showed distinct temporal clusters of responses with enrichment of oxidative dysfunction and senescence-related pathways/proteins during hyperammonemia and after ammonia withdrawal. Functional and metabolic studies showed defects in electron transport chain complexes I, III, and IV; loss of supercomplex assembly; decreased ATP synthesis; increased free radical generation with oxidative modification of proteins/lipids; and senescence-associated molecular phenotype-increased β-galactosidase activity and expression of p16INK, p21, and p53. These perturbations were partially reversed by ammonia lowering. Dysregulated ammonia metabolism caused reversible mitochondrial dysfunction by transcriptional and translational perturbations in multiple pathways with a distinct skeletal muscle senescence-associated molecular phenotype.senescence-associated molecular phenotype.)
Chowdhury 2000 Clin Chim Acta + (Amniocytes represent a population of foeta … Amniocytes represent a population of foetal cells that can be used for prenatal diagnosis in families with suspected mitochondrial oxidative phosphorylation (OXPHOS) defects. In this paper, we present a complex protocol for evaluation of the function of mitochondrial OXPHOS enzymes in cultured amniocytes using three independent and complementary methods: (a) spectrophotometry as a tool for determination of the capacities of mitochondrial respiratory-chain enzymes (NADH ubiquinone oxidoreductase, succinate- and glycerophosphate cytochrome c reductase, cytochrome c oxidase and citrate synthase); (b) polarography as a tool for the evaluation of mitochondrial OXPHOS enzyme functions in situ using digitonin-permeabilised amniocytes (rotenone-sensitive oxidation of pyruvate+malate, antimycin A-sensitive oxidation of succinate, KCN-sensitive oxidation of cytochrome c, ADP-activated substrate oxidation) and (c) cytofluorometric determination of tetramethyl rhodamine methyl ester (TMRM) fluorescence in digitonin-permeabilised amniocytes as a sensitive way to determine the mitochondrial membrane potential under steady-state conditions (state 4 with succinate). These protocols are presented together with reference control values using 9–22 independent cultures of amniocytes.g 9–22 independent cultures of amniocytes.)
Pozenel 2019 Cells + (Amniotic cells show exciting stem cell fea … Amniotic cells show exciting stem cell features, which has led to the idea of using living cells of human amniotic membranes (hAMs) in toto for clinical applications. However, under common cell culture conditions, viability of amniotic cells decreases rapidly, whereby reasons for this decrease are unknown so far. Recently, it has been suggested that loss of tissue tension ''in vivo'' leads to apoptosis. Therefore, the aim of this study was to investigate the effect of tissue distention on the viability of amniotic cells ''in vitro''. Thereby, particular focus was put on vital mitochondria-linked parameters, such as respiration and ATP synthesis. Biopsies of hAMs were incubated for 7-21 days either non-distended or distended. We observed increased B-cell lymphoma 2-associated X protein (BAX)/B-cell lymphoma (BCL)-2 ratios in non-distended hAMs at day seven, followed by increased caspase 3 expression at day 14, and, consequently, loss of viability at day 21. In contrast, under distention, caspase 3 expression increased only slightly, and mitochondrial function and cellular viability were largely maintained. Our data suggest that a mechano-sensing pathway may control viability of hAM cells by triggering mitochondria-mediated apoptosis upon loss of tension ''in vitro''. Further studies are required to elucidate the underlying molecular mechanisms between tissue distention and viability of hAM cells.sue distention and viability of hAM cells.)
Antona 2023 Cell Death Discov + (Among all cancers, colorectal cancer (CRC) … Among all cancers, colorectal cancer (CRC) is the 3rd most common and the 2nd leading cause of death worldwide. New therapeutic strategies are required to target cancer stem cells (CSCs), a subset of tumor cells highly resistant to present-day therapy and responsible for tumor relapse. CSCs display dynamic genetic and epigenetic alterations that allow quick adaptations to perturbations. Lysine-specific histone demethylase 1A (KDM1A also known as LSD1), a FAD-dependent H3K4me1/2 and H3K9me1/2 demethylase, was found to be upregulated in several tumors and associated with a poor prognosis due to its ability to maintain CSCs staminal features. Here, we explored the potential role of KDM1A targeting in CRC by characterizing the effect of KDM1A silencing in differentiated and CRC stem cells (CRC-SCs). In CRC samples, KDM1A overexpression was associated with a worse prognosis, confirming its role as an independent negative prognostic factor of CRC. Consistently, biological assays such as methylcellulose colony formation, invasion, and migration assays demonstrated a significantly decreased self-renewal potential, as well as migration and invasion potential upon KDM1A silencing. Our untargeted multi-omics approach (transcriptomic and proteomic) revealed the association of KDM1A silencing with CRC-SCs cytoskeletal and metabolism remodeling towards a differentiated phenotype, supporting the role of KDM1A in CRC cells stemness maintenance. Also, KDM1A silencing resulted in up-regulation of miR-506-3p, previously reported to play a tumor-suppressive role in CRC. Lastly, loss of KDM1A markedly reduced 53BP1 DNA repair foci, implying the involvement of KDM1A in the DNA damage response. Overall, our results indicate that KDM1A impacts CRC progression in several non-overlapping ways, and therefore it represents a promising epigenetic target to prevent tumor relapse.pigenetic target to prevent tumor relapse.)
Gnaiger 2013 Abstract Mito2013 + (Among all humans, the Polar Inuit of Thule … Among all humans, the Polar Inuit of Thule and Qaarnaak in Greenland are the northernmost population, limited to 302 in 1950 and dwindling to 180 in 2004. This human heritage of a culture and physiological type is endangered not only by a historical politically forced limitation of their territory, but by the current effects of global environmental pollution and climate change, causing social destabilization and a shift towards an unhealthy sedentary life style in contrast to the traditional active life style of Inuit hunters. 10 years ago the uncoupling hypothesis was presented for mitochondrial haplogroups of arctic populations suggesting that lower coupling of mitochondrial respiration to ATP production was selected for in favour of higher heat dissipation as an adaptation to cold climates [1,2]. It has been hypothesized that climatic pressures exerted selection for mitochondrial haplogroups in arctic populations as an adaptation to the cold, by increasing heat production through a higher mitochondrial proton leak. We studied muscle mitochondrial function in traditional Inuit hunters from Qaarnaak, Northern Greenland and sedentary Caucasian Danes who engaged in a 42 day ski sojourn across the polar ice caps (80-82o latitude). Small muscle biopsies were obtained from the leg (vastus lateralis) and arm (deltoid) muscles in both Inuit and Danes and mitochondrial function was assessed by high-resolution respirometry [3,4]. OXPHOS capacity in the leg was lower in Inuit compared to Danes consistent with differences in mitochondrial density. Nonetheless, Inuit had a higher OXPHOS capacity with fat substrate in both leg and arm muscles. LEAK respiration was proportionate with OXPHOS such that coupling control was equivalent between groups and across muscles of both arm and leg. After 42 days of skiing Danes demonstrated adaptive substrate control through an increase in fatty acid oxidation towards levels of the Inuit. Biochemical coupling efficiency was preserved across variations in mtDNA, muscle fibre type, uncoupling protein-3 content, muscle OXPHOS capacity, leg and arm muscle, and acclimatization level. This study refutes the hypothesis that uncoupling is higher in skeletal muscle of arctic haplotype populations and reveals that mitochondrial coupling control is tightly conserved across haplotype groups and training status despite large adaptive capacities for substrate oxidation.aptive capacities for substrate oxidation.)
Francisco 2018 J Neurochem + (Among mitochondrial NADP-reducing enzymes, … Among mitochondrial NADP-reducing enzymes, nicotinamide nucleotide transhydrogenase (NNT) establishes an elevated matrix NADPH/NADP+ by catalyzing the reduction of NADP+ at the expense of NADH oxidation coupled to inward proton translocation across the inner mitochondrial membrane. Here, we characterize NNT activity and mitochondrial redox balance in the brain using a congenic mouse model carrying the mutated ''Nnt'' gene from the C57BL/6J strain. The absence of NNT activity resulted in lower total NADPH sources activity in the brain mitochondria of young mice, an effect that was partially compensated in aged mice. Nonsynaptic mitochondria showed higher NNT activity than synaptic mitochondria. In the absence of NNT, an increased release of H2O2 from mitochondria was observed when the metabolism of respiratory substrates occurred with restricted flux through relevant mitochondrial NADPH sources or when respiratory complex I was inhibited. In accordance, mitochondria from ''Nnt''-/- brains were unable to sustain NADP in its reduced state when energized in the absence of carbon substrates, an effect aggravated after H2O2 bolus metabolism. These data indicate that the lack of NNT in brain mitochondria impairs peroxide detoxification, but peroxide detoxification can be partially counterbalanced by concurrent NADPH sources depending on substrate availability. Notably, only brain mitochondria from ''Nnt''-/- mice chronically fed a high-fat diet exhibited lower activity of the redox-sensitive aconitase, suggesting that brain mitochondrial redox balance requires NNT under the metabolic stress of a high-fat diet. Overall, the role of NNT in the brain mitochondria redox balance especially comes into play under mitochondrial respiratory defects or high-fat diet. This article is protected by copyright. All rights reserved.ay under mitochondrial respiratory defects or high-fat diet. This article is protected by copyright. All rights reserved.)
Sharma 2023 Biosci Biotechnol Biochem + (Among the branched chain amino acids (BCAA … Among the branched chain amino acids (BCAAs), leucine and isoleucine have been well-studied for their roles in improving mitochondrial function and reducing oxidative stress. However, role of valine in mitochondrial function regulation and oxidative stress management remains elusive. This study investigated valine effect on mitochondrial function and oxidative stress ''in vitro''. Valine increased expression of genes involved in mitochondrial biogenesis and dynamics. It upregulates mitochondrial function at Complexes I, II and IV levels of electron transport chain. Flow cytometry studies revealed, valine reduced oxidative stress by significantly lowering mitochondrial reactive oxygen species (ROS) and protein expression of 4 hydroxynonenal. Functional role of valine against oxidative stress was analyzed by XFe96 Analyzer. Valine sustained oxidative phosphorylation and improved ATP generation rates during oxidative stress. In conclusion, our findings shed more light on the critical function of valine in protecting mitochondrial function thereby preventing mitochondrial/cellular damage induced by oxidative stress.llular damage induced by oxidative stress.)
Foriel 2015 Abstract MiP2015 + (Among the wide range of mitochondrial diso … Among the wide range of mitochondrial disorders, defects in the oxidative phosphorylation (OxPhos) are the most prevalent. OxPhos deficiencies often lead to early death and are associated with severe and highly variable clinical symptoms. Despite intense efforts in the comprehension of the mechanisms underlying mitochondrial disorders, patients are still without effective treatment. The need of predictive ''in vivo'' models of the pathology is an important issue in the development of new therapeutics in order to study their therapeutic potential, toxicity and pharmacokinetics. Due to the extreme genetic and phenotypic heterogeneity of OxPhos disorders one cannot rely on a single in ''vivo model''. Here we present the method and strategy we use to create, characterize and validate a set of ''Drosophila melanogaster'' models of nuclear DNA-encoded OxPhos subunits and preliminary results of systematic evaluation of Khondrion´s lead compound. We primarily focus on complex I by knocking down the core and accessory subunits the most prone to mutation in patients and selecting phenotypes-readouts suitable for drug screening (death at critical stages of development, survival curves, ROS level).These models will represent a valuable tool with predictive power to evaluate new potential therapeutics as an initial step in the drug development process.tial step in the drug development process.)
Kohoutova 2018 Physiol Res + (Ample experimental evidence suggests that … Ample experimental evidence suggests that sepsis could interfere with any mitochondrial function; however, the true role of mitochondrial dysfunction in the pathogenesis of sepsis-induced multiple organ dysfunction is still a matter of controversy. This review is primarily focused on mitochondrial oxygen consumption in various animal models of sepsis in relation to human disease and potential sources of variability in experimental results documenting decrease, increase or no change in mitochondrial respiration in various organs and species. To date, at least three possible explanations of sepsis-associated dysfunction of the mitochondrial respiratory system and consequently impaired energy production have been suggested: 1. Mitochondrial dysfunction is secondary to tissue hypoxia. 2. Mitochondria are challenged by various toxins or mediators of inflammation that impair oxygen utilization (cytopathic hypoxia). 3. Compromised mitochondrial respiration could be an active measure of survival strategy resembling stunning or hibernation. To reveal the true role of mitochondria in sepsis, sources of variability of experimental results based on animal species, models of sepsis, organs studied, or analytical approaches should be identified and minimized by the use of appropriate experimental models resembling human sepsis, wider use of larger animal species in preclinical studies, more detailed mapping of interspecies differences and organ-specific features of oxygen utilization in addition to use of complex and standardized protocols evaluating mitochondrial respiration.cols evaluating mitochondrial respiration.)
Greenway 2019 J Evol Biol + (Ample sperm production is essential for su … Ample sperm production is essential for successful male reproduction in many species. The amount of sperm a male can produce is typically constrained by the size of his testes, which can be energetically expensive to grow and maintain. Whilst the economics of ejaculate allocation has been the focus of much theoretical and empirical literature, relatively little attention has been paid to individual adult variation and plasticity at the source of sperm production, the testes themselves. We experimentally address this issue using the insect ''Narnia femorata'' Stål (Hemiptera: Coreidae). We established the metabolic cost of testicular tissue, then quantified variation in individual testes mass in response to multiple mate quality and quantity treatments. We uncovered extreme variation across individuals and considerable short-term effects of mating activity on testes dry mass. Importantly, the observed variation in testes mass was associated with notable fitness consequences; females paired with males with larger testes had greater hatching success. Overall, pairing with a female resulted in a 11% reduction in dry testes mass. Despite this apparent considerable mating investment, we found no evidence of strategic allocation to higher quality females or longer-term changes in testes mass. The dynamic nature of testes mass and its metabolic cost is vital to consider in the context of re-mating rates, polyandry benefits and general mating system dynamics both in this species and more broadly.© 2019 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2019 European Society For Evolutionary Biology.ropean Society For Evolutionary Biology.)
Miwa 2015 Free Radic Biol Med + (Amplex Red is a fluorescent probe that is … Amplex Red is a fluorescent probe that is widely used to detect hydrogen peroxide (H2O2) in a reaction where it is oxidised to resorufin by horseradish peroxidase (HRP) as a catalyst. This assay is highly rated amongst other similar probes thanks to its superior sensitivity and stability. However, we report here that Amplex Red is readily convertedto resorufin by a carboxylesterase without requiring H2O2, horseradish peroxidase or oxygen: this reaction is seen in various tissue samples such as liver and kidney as well as in cultured cells, causing a serious distortion of H2O2 measurements. The reaction can be inhibited by Phenylmethyl sulfonyl fluoride (PMSF) at concentrations which do not disturb mitochondrial function nor the ability of the Amplex Red-HRP system to detect H2O2. ''In vitro'' experiments and ''in silico'' docking simulations indicate that carboxylesterases 1 and 2 recognise Amplex Red with the same kinetics as carboxylesterase-containing mitochondria. We propose two different approaches to correct for this problem and re-evaluate the commonly performed experimental procedure for the detection of H2O2 release from isolated liver mitochondria. Our results call for a serious re-examination of previous data.on of H2O2 release from isolated liver mitochondria. Our results call for a serious re-examination of previous data.)
Dębski 2016 Free Radic Biol Med + (Amplex® Red (10-acetyl-3,7-dihydroxyphenox … Amplex® Red (10-acetyl-3,7-dihydroxyphenoxazine) is a fluorogenic probe widely used to detect and quantify hydrogen peroxide in biological systems. Detection of hydrogen peroxide is based on peroxidase-catalyzed oxidation of Amplex® Red to resorufin. In this study we investigated the mechanism of one-electron oxidation of Amplex® Red and we present the spectroscopic characterization of transient species formed upon the oxidation. Oxidation process has been studied by a pulse radiolysis technique with one-electron oxidants (N3(•), CO3(•-),(•)NO2 and GS(•)). The rate constants for the Amplex® Red oxidation by N3(•) ((2)k=2.1·10(9)M(-1)s(-1), at pH=7.2) and CO3(•-) ((2)k=7.6·10(8)M(-1)s(-1), at pH=10.3) were determined. Two intermediates formed during the conversion of Amplex® Red into resorufin have been characterized. Based on the results obtained, the mechanism of transformation of Amplex® Red into resorufin, involving disproportionation of the Amplex® Red-derived radical species, has been proposed. The results indicate that peroxynitrite-derived radicals, but not peroxynitrite itself, are capable to oxidize Amplex® Red to resorufin. We also demonstrate that horseradish peroxidase can catalyze oxidation of Amplex® Red not only by hydrogen peroxide, but also by peroxynitrite, which needs to be considered when employing the probe for hydrogen peroxide detection.the probe for hydrogen peroxide detection.)
Lopez 2017 Sci Rep + (Amyloid precursor protein (APP) and its ex … Amyloid precursor protein (APP) and its extracellular domain, soluble APP alpha (sAPPα) play important physiological and neuroprotective roles. However, rare forms of familial Alzheimer's disease are associated with mutations in APP that increase toxic amyloidogenic cleavage of APP and produce amyloid beta (Aβ) at the expense of sAPPα and other non-amyloidogenic fragments. Although mitochondrial dysfunction has become an established hallmark of neurotoxicity, the link between Aβ and mitochondrial function is unclear. In this study we investigated the effects of increased levels of neuronal APP or Aβ on mitochondrial metabolism and gene expression, in human SH-SY5Y neuroblastoma cells. Increased non-amyloidogenic processing of APP, but not Aβ, profoundly decreased respiration and enhanced glycolysis, while mitochondrial DNA (mtDNA) transcripts were decreased, without detrimental effects to cell growth. These effects cannot be ascribed to Aβ toxicity, since higher levels of endogenous Aβ in our models do not cause oxidative phosphorylation (OXPHOS) perturbations. Similarly, chemical inhibition of β-secretase decreased mitochondrial respiration, suggesting that non-amyloidogenic processing of APP may be responsible for mitochondrial changes. Our results have two important implications, the need for caution in the interpretation of mitochondrial perturbations in models where APP is overexpressed, and a potential role of sAPPα or other non-amyloid APP fragments as acute modulators of mitochondrial metabolism.te modulators of mitochondrial metabolism.)
Krako 2016 Abstract MitoFit Science Camp 2016 + (Amyloid β oligomers (AβOs) are crucially i … Amyloid β oligomers (AβOs) are crucially involved in Alzheimer’s disease (AD). They are still ˝mysterious entities˝ in terms of their precise molecular composition, their in-cell formation, traffic and actions. We have recently established a subcellularly localized conformational-selective interference approach, based on the expression of an intrabody against AβOs in the endoplasmic reticulum (ER) [1]. This intrabody is a recombinant antibody domain (scFvA13), previously isolated in our laboratory, that selectively binds to AβOs, with high selectivity and specificity with respect to Aβ monomeric species or fibrils [2]. For these studies, we exploited the 7PA2 cells (familial AD CHO cell model), the gold standard for natural AβOs production. Mitochondrial membrane potential was evaluated following the mitochondrial electrophoretic accumulation of the membrane permeable fluorescent cationic probe JC-1. Mitochondrial respiration was measured by high-resolution respirometry in intact and permeabilized cells. The concentration of ATP was quantified by chemiluminometry under basal cell metabolic conditions. Recently, we described that 7PA2 cells have another characteristic relevant to Alzheimer’s disease – a severe mitochondrial dysfunction, due to a chronic AβOs exposure and production [3]. We have newly established cell line, the 7PA2-A13K, as the model for conformational-selective interference with AβOs inside the endoplasmic reticulum (ER). These cells show a significantly lower level of secreted AβOs, without their intracellular accumulation and most importantly, through this modulatory effects on the levels and assembly of AβOs, a strong rescue of mitochondrial dysfunctions and bioenergetic deficit occurs (Figure 1). These data provide an important evidence for the fact that the AβOs are formed inside a cell, precisely in the ER, from where they exert their toxic action on mitochondrial physiology. These data contribute to the recent findings about the importance of the ER – mitochondria interplay in the pathogenesis of Alzheimer’s disease and highlight the subcellular compartment, called MAM – mitochondria associated ER membranes - as an important cellular target for the intracellular actions of AβOs. Future studies, that will extend these findings from a well defined cell model to neurons and, possibly to human neurons, will have to take into account the importance of organelle continuity and cross-talk for the cell homeostasis and AD pathology. From a methodological point of view, these results provide the first example of a functional experimental approach, conformational selective interference (CSI), that could find many applications for the studies of protein modifications ''in vivo''.dies of protein modifications ''in vivo''.)
Ng 2019 J Biol Chem + (Amyloid β1-42 (Aβ1-42) peptide is involved … Amyloid β1-42 (Aβ1-42) peptide is involved in Alzheimer's disease (AD) pathogenesis and is prone to glycation, an irreversible process resulting in proteins with accumulated advanced glycated end products (AGEs). Nε-(carboxyethyl)lysine (CEL) is a common AD-associated AGE, occurring at either Lys-16 or Lys-28 of Aβ1-42. Methylglyoxal is commonly used for the unspecific glycation of Aβ1-42, which results in a complex mixture of AGE-modified peptides and makes interpretation of a causative AGE at a specific amino acid residue difficult. Here, we addressed this challenge by chemically synthesizing defined CEL glycations on Aβ1-42 at Lys-16 (Aβ-CEL16), Lys-28 (Aβ-CEL28), and both Lys-16 and -28 (Aβ-CEL16&28). We demonstrate that the double CEL glycation at Lys-16/28 of Aβ1-42 had the most profound impact on amyloid fibril formation. ''In silico'' predictions indicated that Aβ-CEL16&28 had a substantially decreased free-energy change, contributing to fibril destabilization, and a decreased aggregation rate. Single CEL glycations at Lys-28 had the least impact on fibril formation, and Lys-16 CEL glycations delayed fibril formation. We also tested these peptides for neuronal toxicity and impact on mitochondrial function in a retinoic acid-differentiated SH-SY5Y human neuroblastoma cell line and found that only Aβ-CEL16 and Aβ-CEL28 are neurotoxic, possibly through a non-mitochondrial pathway, whereas Aβ-CEL16&28 is not neurotoxic. Interestingly, Aβ-CEL16&28 depolarized the mitochondrial membrane potential, and Aβ-CEL16 increased mitochondrial respiration at complex II, possibly indicating mitophagy or an alternative metabolic route, respectively. In summary, our results provide insights relevant for potential therapeutic approaches against neurotoxic CEL glycated Aβ1-42.Published under license by The American Society for Biochemistry and Molecular Biology, Inc.ety for Biochemistry and Molecular Biology, Inc.)
Souza da Silva 2020 Mol Neurobiol + (Amyloid-β oligomers (AβOs) toxicity causes … Amyloid-β oligomers (AβOs) toxicity causes mitochondrial dysfunction, leading to synaptic failure in Alzheimer's disease (AD). Considering presynaptic high energy demand and tight Ca2+ regulation, impairment of mitochondrial function can lead to deteriorated neural activity and cell death. In this study, an AD mouse model induced by ICV (intracerebroventricular) injection of AβOs was used to investigate the toxicity of AβOs on presynaptic function. As a therapeutic approach, GUO (guanosine) was given by oral route to evaluate the neuroprotective effects on this AD model. Following 24 h and 48 h from the model induction, behavioral tasks and biochemical analyses were performed, respectively. AβOs impaired object recognition (OR) short-term memory and reduced glutamate uptake and oxidation in the hippocampus. Moreover, AβOs decreased spare respiratory capacity, reduced ATP levels, impaired Ca2+ handling, and caused mitochondrial swelling in hippocampal synaptosomes. Guanosine crossed the BBB, recovered OR short-term memory, reestablished glutamate uptake, recovered mitochondrial Ca2+ homeostasis, and partially prevented mitochondrial swelling. Therefore, this endogenous purine presented a neuroprotective effect on presynaptic mitochondria and should be considered for further studies in AD models.nsidered for further studies in AD models.)
Cacabelos 2016 Acta Neuropathol Commun + (Amyotrophic lateral sclerosis (ALS) is a m … Amyotrophic lateral sclerosis (ALS) is a motor neuron disease with a gender bias towards major prevalence in male individuals. Several data suggest the involvement of oxidative stress and mitochondrial dysfunction in its pathogenesis, though differences between genders have not been evaluated. For this reason, we analysed features of mitochondrial oxidative metabolism, as well as mitochondrial chain complex enzyme activities and protein expression, lipid profile, and protein oxidative stress markers, in the Cu,Zn superoxide dismutase with the G93A mutation (hSOD1-G93A)- transgenic mice and Neuro2A(N2A) cells overexpressing hSOD1-G93A.Our results show that overexpression of hSOD1-G93A in transgenic mice decreased efficiency of mitochondrial oxidative phosphorylation, located at complex I, revealing a temporal delay in females with respect to males associated with a parallel increase in selected markers of protein oxidative damage. Further, females exhibit a fatty acid profile with higher levels of docosahexaenoic acid at 30 days. Mechanistic studies showed that hSOD1-G93A overexpression in N2A cells reduced complex I function, a defect prevented by 17β-estradiol pretreatment. In conclusion, ALS-associated SOD1 mutation leads to delayed mitochondrial dysfunction in female mice in comparison with males, in part attributable to the higher oestrogen levels of the former. This study is important in the effort to further understanding of whether different degrees of spinal cord mitochondrial dysfunction could be disease modifiers in ALS.unction could be disease modifiers in ALS.)
Magri 2022 Abstract Bioblast + (Amyotrophic lateral sclerosis (ALS) is a f … Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease which affects motor neurons (MNs). Many familial and sporadic forms correlate with mutations in the gene encoding the antioxidant enzyme Cu/Zn Superoxide Dismutase (SOD1). Among mutants, the dismutase-active SOD1 G93A forms toxic aggregates on the cytosolic surface of outer mitochondrial membrane (OMM), using the Voltage-Dependent Anion Channel 1 (VDAC1) as binding site [1]. VDAC1 is the most abundant OMM pore-forming protein and allows the trafficking of metabolites (pyruvate, malate), ions, NAD+/NADH and ATP/ADP across the membrane; furthermore, it serves as an anchor for many cytosolic proteins, mostly for Hexokinases (HKs) [2]. However, in ALS MNs, the mitochondrial accumulation of SOD1 G93A impairs molecules exchange through VDAC1 and displaces HKs from mitochondria, promoting the organelle dysfunction and cell death [1-2].By a means of ''in vitro'' and ''in cellulo'' approaches, we previously demonstrated that HK1 and SOD1 G93A compete for the same mitochondrial binding site, VDAC1 [3]. Based on these observations, we developed a small synthetic peptide corresponding to the first 11 amino acid residues of the HK1 N-terminal domain (NHK1) [3]. NHK1 is able to modulates VDAC1 activity when it is reconstituted in artificial membranes; when added to ALS MNs, the peptide promotes a complete recovery of the cell viability in a dose-response manner [3-4]. By using High-Resolution Respirometry (HRR), we then analyzed the mitochondrial respiration profile of MN-like cells NSC34 stably expressing SOD1 G93A. Our results indicate that NHK1 promotes a partial increase of oxygen consumption corresponding to ROUTINE and OXPHOS state. As demonstrated by FCRs analysis, the peptide stimulates a significative decrease of the LEAK respiration while increases net respiration and coupling efficiency linked to OXPHOS state [4]. This effect is probably due to the reduction of ~70 % of VDAC1-SOD1 G93A aggregates observed in the mitochondrial fraction of cells treated with NHK1 [4].In conclusion, our results suggest that NHK1 drives the recovery of compromised mitochondrial respiration typical of ALS and provide new insights into the development of therapeutic molecules to fight the disease. Overall, our work helps to better understand the relationship between altered mitochondrial metabolism and MNs death.# Israelson A, Arbel N, da Cruz S, Ilieva H, Yamanaka K, Shoshan-Barmatz V, Cleveland DW (2010) Misfolded mutant SOD1 directly inhibits VDAC1 conductance in a mouse model of inherited ALS. https://doi.org/10.1016/j.neuron.2010.07.019# Magrì A, Reina S, De Pinto V (2018) VDAC1 as pharmacological target in cancer and neurodegeneration: focus on its role in apoptosis. https://doi.org/10.3389/fchem.2018.00108# Magrì A, Belfiore R, Reina S, Tomasello MF, Di Rosa MC, Guarino F, Leggio L, De Pinto V, Messina A (2016) Hexokinase I N-terminal based peptide prevents the VDAC1-SOD1 G93A interaction and re-establishes ALS cell viability. https://doi.org/10.1038/srep34802# Magrì A, Risiglione P, Caccamo A, Formicola B, Tomasello MF, Arrigoni C, Zimbone S, Guarino F, Re F, Messina A (2021) Small Hexokinase 1 peptide against toxic SOD1 G93A mitochondrial accumulation in ALS rescues the ATP-related respiration. https://doi.org/10.3390/biomedicines9080948ration. https://doi.org/10.3390/biomedicines9080948 )
Miquel 2014 Free Radic Biol Med + (Amyotrophic lateral sclerosis (ALS) is a f … Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by motor neuron degeneration that ultimately results in progressive paralysis and death. Growing evidence indicates that mitochondrial dysfunction and oxidative stress contribute to motor neuron degeneration in ALS. To further explore the hypothesis that mitochondrial dysfunction and nitroxidative stress contribute to disease pathogenesis at the ''in vivo'' level, we assessed whether the mitochondria-targeted antioxidant [10-(4,5-dimethoxy-2-methyl-3,6-dioxo-1,4- cyclohexadien-1-yl)decyl]triphenylphosphonium methanesulfonate (MitoQ) can modify disease progression in the SOD1G93A mouse model of ALS. To do this, we administered MitoQ (500µM) in the drinking water of SOD1G93A mice from a time when early symptoms of neurodegeneration become evident at 90 days of age until death. This regime is a clinically plausible scenario and could be more easily translated to patients as this corresponds to initiating treatment of patients after they are first diagnosed with ALS. MitoQ was detected in all tested tissues by liquid chromatography/mass spectrometry after 20 days of administration. MitoQ treatment slowed the decline of mitochondrial function, both in the spinal cord and quadriceps muscle as measured by high-resolution respirometry. Importantly, nitroxidative markers and pathological signs in the spinal cord of MitoQ-treated animals were markedly reduced and neuromuscular junctions were recovered associated to a significant increase in hind-limb strength. Finally, MitoQ treatment significantly prolonged the lifespan of SOD1G93A mice. Our results support a role for mitochondrial nitroxidative damage and dysfunction in the pathogenesis of ALS and suggest that mitochondria-targeted antioxidants may be of pharmacological use for ALS treatment. of pharmacological use for ALS treatment.)
Ladd 2017 Brain Res + (Amyotrophic lateral sclerosis (ALS) is a g … Amyotrophic lateral sclerosis (ALS) is a generally fatal neurodegenerative disease of adults that produces weakness and atrophy due to dysfunction and death of upper and lower motor neurons. We used RNA-sequencing (RNA-seq) to analyze expression of all mitochondrial DNA (mtDNA)-encoded respiratory genes in ALS and CTL human cervical spinal cords (hCSC) and isolated motor neurons. We analyzed with RNA-seq mtDNA gene expression in human neural stem cells (hNSC) exposed to recombinant human mitochondrial transcription factor A (rhTFAM), visualized in 3-dimensions clustered gene networks activated by rhTFAM, quantitated their interactions with other genes and determined their gene ontology (GO) families. RNA-seq and quantitative PCR (qPCR) analyses showed reduced mitochondrial gene expression in ALS hCSC and ALS motor neurons isolated by laser capture microdissection (LCM), and revealed that hNSC and CTL human cervical spinal cords were similar. Rats treated with i.v. rhTFAM showed a dose-response increase in brain respiration and an increase in spinal cord mitochondrial gene expression. Treatment of hNSC with rhTFAM increased expression of mtDNA-encoded respiratory genes and produced one major and several minor clusters of gene interactions. Gene ontology (GO) analysis of rhTFAM-stimulated gene clusters revealed enrichment in GO families involved in RNA and mRNA metabolism, suggesting mitochondrial-nuclear signaling. In postmortem ALS hCSC and LCM-isolated motor neurons we found reduced expression of mtDNA respiratory genes. In hNSC's rhTFAM increased mtDNA gene expression and stimulated mRNA metabolism by unclear mechanisms. rhTFAM may be useful in improving bioenergetic function in ALS.Copyright © 2017 Elsevier B.V. All rights reserved. © 2017 Elsevier B.V. All rights reserved.)
Martinez-Palma 2018 Neurotherapeutics + (Amyotrophic lateral sclerosis (ALS) is a f … Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron (MN) degeneration and gliosis. Neonatal astrocytes obtained from the SOD1G93A rat model of ALS exhibit mitochondrial dysfunction and neurotoxicity that can be reduced by dichloroacetate (DCA), a metabolic modulator that has been used in humans, and shows beneficial effects on disease outcome in SOD1G93A mice. Aberrant glial cells (AbGC) isolated from the spinal cords of adult paralytic SOD1G93A rats exhibit highly proliferative and neurotoxic properties and may contribute to disease progression. Here we analyze the mitochondrial activity of AbGC and whether metabolic modulation would modify their phenotypic profile. Our studies revealed fragmented mitochondria and lower respiratory control ratio in AbGC compared to neonatal SOD1G93A and nontransgenic rat astrocytes. DCA (5 mM) exposure improved AbGC mitochondrial function, reduced their proliferative rate, and importantly, decreased their toxicity to MNs. Furthermore, oral DCA administration (100 mg/kg, 10 days) to symptomatic SOD1G93A rats reduced MN degeneration, gliosis, and the number of GFAP/S100β double-labeled hypertrophic glial cells in the spinal cord. DCA treatment of AbGC reduced extracellular lactate levels indicating that the main recognized DCA action, targeting the pyruvate dehydrogenase kinase/pyruvate dehydrogenase complex, may underlie our findings. Our results show that AbGC metabolic phenotype is related to their toxicity to MNs and indicate that its modulation can reduce glial mediated pathology in the spinal cord. Together with previous findings, these results further support glial metabolic modulation as a valid therapeutic strategy in ALS.on as a valid therapeutic strategy in ALS.)
Veyrat-Durebex 2019 Mol Neurobiol + (Amyotrophic lateral sclerosis (ALS) is cha … Amyotrophic lateral sclerosis (ALS) is characterized by a wide metabolic remodeling, as shown by recent metabolomics and lipidomics studies performed in samples from patient cohorts and experimental animal models. Here, we explored the metabolome and lipidome of fibroblasts from sporadic ALS patients (n = 13) comparatively to age- and sex-matched controls (n = 11), and the subcellular fraction containing the mitochondria and endoplasmic reticulum (mito-ER), given that mitochondrial dysfunctions and ER stress are important features of ALS patho-mechanisms. We also assessed the mitochondrial oxidative respiration and the mitochondrial genomic (mtDNA) sequence, although without yielding significant differences. Compared to controls, ALS fibroblasts did not exhibit a mitochondrial respiration defect nor an increased proportion of mitochondrial DNA mutations. In addition, non-targeted metabolomics and lipidomics analyses identified 124 and 127 metabolites, and 328 and 220 lipids in whole cells and the mito-ER fractions, respectively, along with partial least-squares-discriminant analysis (PLS-DA) models being systematically highly predictive of the disease. The most discriminant metabolomic features were the alteration of purine, pyrimidine, and energetic metabolisms, suggestive of oxidative stress and of pro-inflammatory status. The most important lipidomic feature in the mito-ER fraction was the disturbance of phosphatidylcholine PC (36:4p) levels, which we had previously reported in the cerebrospinal fluid of ALS patients and in the brain from an ALS mouse model. Thus, our results reveal that fibroblasts from sporadic ALS patients share common metabolic remodeling, consistent with other metabolic studies performed in ALS, opening perspectives for further exploration in this cellular model in ALS.exploration in this cellular model in ALS.)
Tungtur 2021 Sci Rep + (Amyotrophic lateral sclerosis (ALS) remain … Amyotrophic lateral sclerosis (ALS) remains a devastating motor neuron disease with limited treatment options. Oxaloacetate treatment has a neuroprotective effect in rodent models of seizure and neurodegeneration. Therefore, we treated the ALS model superoxide dismutase 1 (SOD1) G93A mice with oxaloacetate and evaluated their neuromuscular function and lifespan. Treatment with oxaloacetate beginning in the presymptomatic stage significantly improved neuromuscular strength measured during the symptomatic stage in the injected mice compared to the non-treated group. Oxaloacetate treatment starting in the symptomatic stage significantly delayed limb paralysis compared with the non-treated group. For lifespan analysis, oxaloacetate treatment did not show a statistically significant positive effect, but the treatment did not shorten the lifespan. Mechanistically, SOD1YG93A mice showed increased levels of tumor necrosis factor-α (TNFα) and peroxisome proliferative activated receptor gamma coactivator 1α (PGC-1α) mRNAs in the spinal cord. However, oxaloacetate treatment reverted these abnormal levels to that of wild-type mice. Similarly, the altered expression level of total NF-κB protein returned to that of wild-type mice with oxaloacetate treatment. These results suggest that the beneficial effects of oxaloacetate treatment in SOD1G93A mice may reflect the effects on neuroinflammation or bioenergetic stress.> mice may reflect the effects on neuroinflammation or bioenergetic stress.)
Sauer 1979 Biochem J + (An NAD(P)+-dependent 'malic' enzyme is sho … An NAD(P)+-dependent 'malic' enzyme is shown to be present in mitochondria from small-intestinal mucosa. The intracellular location, activity and regulatory kinetic properties of the enzyme suggest that it participates in the major energy-producing pathway for net oxidation of glutamine-derived tricarboxylic acid-cycle intermediates.ed tricarboxylic acid-cycle intermediates.)
Nagel 1982 J Biol Chem + (An NAD(P)-dependent malic enzyme with a sp … An NAD(P)-dependent malic enzyme with a specific activity of 40.6 mumol of NADH/min/mg of protein and an isoelectric point of 5.4 was purified to apparent homogeneity from canine small intestinal mucosal mitochondria. The purification procedure employed ammonium sulfate fractionation, Sepharose CL 6B gel filtration, chromatography on DEAE-cellulose to remove the interfering malate dehydrogenase, and affinity chromatography on 2',5'-ADP-Sepharose and NAD-agarose to take advantage of the dual coenzyme specificity. Antibody prepared from the purified enzyme produced a single peak upon cross-rocket immunoelectrophoresis against the mitochondrial sonicate. Continuous polyacrylamide gel electrophoresis showed NAD and NADP activity co-migrating with the native protein band. A single band of protein having an apparent Mr = 62,000 was seen on sodium dodecyl sulfate electrophoresis. At pH 7.3, gel filtration revealed a single peak of activity with NAD and NADP corresponding to an apparent Mr = 282,000. Gradient gel polyacrylamide electrophoresis at pH 9.0 indicated an additional broad band of activity corresponding to a Mr = 141,000. Under physiological conditions therefore the protein appears to exist as a tetramer of Mr = 282,000 composed of four equal subunits, whereas at elevated pH values during electrophoresis, partial dissociation to a dimeric species occurs. dissociation to a dimeric species occurs.)
Marshall 1996 Am J Respir Cell Mol Biol + (An NADPH-oxidase complex containing at lea … An NADPH-oxidase complex containing at least two protein components (gp91-phox and p22-phox) and a unique low redox potential (-245 mV) cytochrome b-245 is the source of superoxide generated for bacterial killing in neutrophils and has been suggested as the oxygen sensor in the carotid body. In pure cultures of smooth muscle cells from calf small pulmonary arteries (300 microns diameter) the presence of the 91 kD protein specific to this cytochrome was demonstrated by Western blot analysis with monoclonal antibody 48. Low-temperature-difference spectrophotometry of homogenates of these cells demonstrated the characteristic cytochrome b-245 spectrum when titrated between redox potentials of -152 and -345 mV, consistent with the low redox potential form. When these same cells were exposed to hypoxia (approximately 40 mmHg), superoxide production increased significantly from 1.4 +/- 0.2 to 73 +/- 12 nmoles.min-1 mg-1 protein. Hypoxic generation of superoxide was inhibited by the NADPH-oxidase inhibitor diphenyleneiodonium (DPI: 10 microM) but not by the mitochondrial inhibitor myxathiazole (10 microM). The hypoxic superoxide increase was significantly greater than that observed from smooth muscle cells from large pulmonary arteries or from large or small systemic arteries. Fluorescence immunocytochemistry revealed the presence of the NADPH-oxidase protein in the walls of pulmonary arteries in rat lung slices, and confocal microscopy showed the complex to be widely distributed in the vicinity of the arterial smooth muscle walls. In hypoxia or norepinephrine (NP)-induced vasoconstriction of pulmonary artery rings from cats, the sensitivity to inhibition by DPI was observed to be significantly greater for hypoxia (ED50 = 0.8 microM) than for NP-induced (ED50 = 13.4 microM) constriction. Together these observations demonstrate that the unique cytochrome b-245 containing NADPH-oxidase is present in pulmonary artery smooth muscle and that an NADPH-oxidase or NADH-oxidoreductase complex is activated to release superoxide by hypoxic conditions. It is concluded that a trans-membrane NADPH-oxidase is the most likely and that activation of this system may be involved in the initiation of hypoxic pulmonary vasoconstriction.ion of hypoxic pulmonary vasoconstriction.)
Mendham 2015 Abstract MiPschool Cape Town 2015 + (An acute bout of exercise activates downst … An acute bout of exercise activates downstream signaling cascades that ultimately result in mitochondrial biogenesis [1]. Elucidating the molecular signaling cascades that stimulate exercise-induced mitochondrial biogenesis carries significance for the prevention of physical-inactivity related diseases [1]. Traditionally, research investigating exercise-induced mitochondrial biogenesis has employed continuous aerobic exercise as the experimental model [2]. An alternative to these more traditional training modes is intermittent running in the form of football-based small-sided games (SSG), which has been reported to improve metabolic health in clinical populations [3]. Accordingly, this study aimed to assess changes in molecular signaling cascades that stimulate mitochondria biogenesis in response to an acute bout of SSG and continuous cycling (CYC) in sedentary, middle-aged men.Nine middle-aged, sedentary but disease-free men completed two respective 40 min exercise bouts (CYC and SSG) in a randomized, cross-over order. Heart rate (HR) and Rating of Perceived Exertion (RPE) were collected during each bout. Venous blood was collected at fasting, immediately, 30, 60 and 240 min post-exercise for measurement of glucose, insulin, cortisol and lactate. Muscle samples were collected at rest, 30 and 240 min post-exercise for the analysis of total PGC-1α, SIRT1, p38MAPK, CAMKIIα and p53, and phosphorylated proteins, p53Ser15, p38Thr180, CAMKIIThr286, AMPKThr172 and p38MAPKThr180/Tyr182. mRNA expression included, PGC-1α, p53, NRF1, NRF2, Tfam and cytochrome c.t;Thr180/Tyr182. mRNA expression included, PGC-1α, p53, NRF1, NRF2, Tfam and cytochrome c.)
Kamberov 2013 Cell + (An adaptive variant of the human Ectodyspl … An adaptive variant of the human Ectodysplasin receptor, EDARV370A, is one of the strongest candidates of recent positive selection from genome-wide scans. We have modeled EDAR370A in mice and characterized its phenotype and evolutionary origins in humans. Our computational analysis suggests the allele arose in central China approximately 30,000 years ago. Although EDAR370A has been associated with increased scalp hair thickness and changed tooth morphology in humans, its direct biological significance and potential adaptive role remain unclear. We generated a knockin mouse model and find that, as in humans, hair thickness is increased in EDAR370A mice. We identify new biological targets affected by the mutation, including mammary and eccrine glands. Building on these results, we find that EDAR370A is associated with an increased number of active eccrine glands in the Han Chinese. This interdisciplinary approach yields unique insight into the generation of adaptive variation among modern humans.of adaptive variation among modern humans.)
Devaux 2015 Abstract MiP2015 + (An adequate oxygen supply is crucial for v … An adequate oxygen supply is crucial for vertebrate survival because ATP is almost exclusively produced by mitochondria though oxidative phosphorlyaltion (OXPHOS). Anoxia leads to ATP depletion and altered metabolic pathways including succinate accumulation which during re-oxygenation triggers a reverse of electron flow to CI accompanied by an enhanced deleterious reactive oxygen species (ROS) production [1]. A few species are able to survive prolonged periods of hypoxia and anoxia at tropical temperatures [2,3]. Two closely related elasmobranchs have very different adative responses to anoxia [2] while both can survive prolonged periods of anoxia the epaulette shark enters a phase of metabolic depression in response to hypoxia or anoxia while the grey carpet shark maintains its metabolic rate but releases additional red blood cells to prolong survival. Mitochondria in heart fibers from the anoxia tolerant epaulette shark maintained mitochondrial efficiency with a low ROS release in response to oxygen limitation, including anoxia [4]. The extent of mitochondrial plasticity in response to diminished oxygen (hypoxia or anoxia) and the triggers involved in this adative process are currently being investigated in our laboratories.Our aim was to determine the response of mitochondrial complexes to elevated succinate after a bout of diminished oxygen in two closely related anoxia tolerant species. Sharks were acclimated in aerated sea-water (100L tanks) held at 22°C and were not fed 24 hours prior to sampling. Sharks were euthanised, the cerebellum isolated and homogenised in cold MiR05. Mitochondrial respiration was measured using high resolution respirometry (Oroboros Oxygraph-2k) with a SUIT protocol. Respiration flux (pmol O2 s-1 mg-1) was determined using DatLab 6.0 and statistical analysis were performed using SPSS™. Calculations were made to determine CI capacity, CII activation and coupling efficiency with and without a 20 min episode of anoxia followed by reoxygenation and stepwise succinate titrations (using a TIP2K microPump).ation and stepwise succinate titrations (using a TIP2K microPump).)
Varela-Lopez 2016 J Gerontol A Biol Sci Med Sci + (An age-dependent model of the periodontium … An age-dependent model of the periodontium was reproduced to evaluate the effect of life-long feeding on a low coenzyme Q10 dosage in n-6, n-3 polyunsaturated fatty acid or monounsaturated fatty acid-based diets on periodontal tissues of young and old rats. Results shown that exacerbated age-related alveolar bone loss previously associated to n-6 polyunsaturated fatty acid diet was attenuated by coenzyme Q10 Gene expression analysis suggests that involved mechanisms might be related to a restored capacity of mitochondria to adapt to aging in gingival cells from rats fed on n-6 polyunsaturated fatty acid. In particular, this could be due to an age-related increase of the rate of mitochondrial biogenesis and a better oxidative and respiratory balance in these animals. From the nutritional and clinical point of view, it is noteworthy that supplementation with coenzyme Q10 could counteract the negative effects of n-6 polyunsaturated fatty acid on alveolar bone loss (a major feature of periodontitis) associated to age.© The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. of The Gerontological Society of America.)
Ye 2013 Anal Biochem + (An approach has been developed to quantita … An approach has been developed to quantitate oxidative phosphorylation in harvested human skin fibroblasts that have been permeabilized with digitonin. In protocol 1, state 3 rates are measured with Complex I and II substrates, followed by uncoupled maximal oxidative capacity measured in the presence of these combined substrates, as well as through Complex IV. In protocol 2, state 3 rates are measured using palmitoylcarnitine to monitor fatty acid oxidation, and duroquinol to assess the flux through Complex III; uncoupled duroquinol oxidation measures maximal oxidative capacity through Complex III. The activity of citrate synthase is determined in every experiment as a marker of the amount of mitochondria per chamber. Data are expressed on the basis of cell count (per million fibroblasts), of protein, or of citrate synthase activity. Cell growth conditions are optimized and it is necessary to keep cultured cells from reaching confluency. Cultures in passages 3 to 10 show reproducible oxidative phosphorylation data. Based on the data from the 15 normal human skin fibroblast lines, we are evaluating the use of this approach to diagnose systemic mitochondrial disease and avoid issues associated with open skeletal muscle biopsy.sociated with open skeletal muscle biopsy.)
Schrauwen-Hinderling 2015 Antioxid Redox Signal + (An early hallmark in the development of ty … An early hallmark in the development of type 2 diabetes is the resistance to the effect of insulin in skeletal muscle and in the heart. Since mitochondrial function was found to be diminished in patients with type 2 diabetes, it was suggested that this defect might be involved in the etiology of insulin resistance. Although several hypotheses were suggested, yet unclear is the mechanistic link between these two phenomena. Herein, we review the evidence for disturbances in mitochondrial function in skeletal muscle and the heart in the diabetic state. Also the mechanisms involved in improving mitochondrial function are considered and, whenever possible, human data is cited. Reported evidence shows that interventions that improve skeletal muscle mitochondrial function also improve insulin sensitivity in humans. In the heart, available data from animal studies suggests that enhancement of mitochondrial function can reverse aging-induced changes in heart function, and can be protective against cardiomyopathy and heart failure.Mitochondria and their functions can be targeted with the aim of improving skeletal muscle insulin sensitivity and cardiac function. However, human clinical intervention studies are needed to fully substantiate the potential of mitochondria as a target to prevent cardiometabolic disease.target to prevent cardiometabolic disease.)
Fuhr 2018 EBioMedicine + (An endogenous molecular clockwork drives v … An endogenous molecular clockwork drives various cellular pathways including metabolism and the cell cycle. Its dysregulation is able to prompt pathological phenotypes including cancer. Besides dramatic metabolic alterations, cancer cells display severe changes in the clock phenotype with likely consequences in tumor progression and treatment response. In this study, we use a comprehensive systems-driven approach to investigate the effect of clock disruption on metabolic pathways and its impact on drug response in a cellular model of colon cancer progression. We identified distinctive time-related transcriptomic and metabolic features of a primary tumor and its metastatic counterpart. A mapping of the expression data to a comprehensive genome-scale reconstruction of human metabolism allowed for the in-depth functional characterization of 24 h-oscillating transcripts and pointed to a clock-driven metabolic reprogramming in tumorigenesis. In particular, we identified a set of five clock-regulated glycolysis genes, ''ALDH3A2'', ''ALDOC'', ''HKDC1'', ''PCK2'', and ''PDHB'' with differential temporal expression patterns. These findings were validated in organoids and in primary fibroblasts isolated from normal colon and colon adenocarcinoma from the same patient. We further identified a reciprocal connection of HKDC1 to the clock in the primary tumor, which is lost in the metastatic cells. Interestingly, a disruption of the core-clock gene ''BMAL1'' impacts on HKDC1 and leads to a time-dependent rewiring of metabolism, namely an increase in glycolytic activity, as well as changes in treatment response. This work provides novel evidence regarding the complex interplay between the circadian clock and metabolic alterations in carcinogenesis and identifies new connections between both systems with pivotal roles in cancer progression and response to therapy.ancer progression and response to therapy.)
Kang 2018 Exp Mol Med + (An excess of reactive oxygen species (ROS) … An excess of reactive oxygen species (ROS) relative to the antioxidant capacity causes oxidative stress, which plays a role in the development of Parkinson's disease (PD). Because mitochondria are both sites of ROS generation and targets of ROS damage, the delivery of antioxidants to mitochondria might prevent or alleviate PD. To transduce the antioxidant protein human metallothionein 1A (hMT1A) into mitochondria, we computationally designed a cell-penetrating artificial mitochondria-targeting peptide (CAMP). The recombinant CAMP-conjugated hMT1A fusion protein (CAMP-hMT1A) successfully localized to the mitochondria. Treating a cell culture model of PD with CAMP-hMT1A restored tyrosine hydroxylase expression and mitochondrial activity and reduced ROS production. Furthermore, injection of CAMP-hMT1A into the brain of a mouse model of PD rescued movement impairment and dopaminergic neuronal degeneration. CAMP-hMT1A delivery into mitochondria might be therapeutic against PD by alleviating mitochondrial damage, and we predict that CAMP could be used to deliver other cargo proteins to the mitochondria. other cargo proteins to the mitochondria.)
Greco 2003 FASEB J + (An extensive analysis has been carried out … An extensive analysis has been carried out of mitochondrial biochemical and bioenergetic properties of fibroblasts, mostly skin-derived, from a large group of subjects ranging in age between 20 wk fetal and 103 yr. A striking age-related change observed in a fundamental process underlying mitochondrial biogenesis and function was the very significant decrease in rate of mitochondrial protein synthesis in individuals above 40 yr. The analysis of endogenous respiration rate revealed a significant decrease in the age range from 40 to 90 yr and a tendency to uncoupling in the samples from subjects above 60 yr. A surprising finding was the occurrence of a subgroup of individuals >or=90 yr old whose skin fibroblasts exhibited an exceptionally high respiration rate. This high rate was not due to respiration uncoupling, rather pointing to a compensatory phenomenon, not involving an increase in mtDNA content, in the corresponding skin fibroblast populations, or, possibly, to a selection of a different cell type secondary to more extensive dermal atrophy. The most important aging-related phenotypic effects observed were those that affected the cell oxidative phosphorylation (OX-PHOS) capacity. These were, in particular, the very significant reduction in the ratio of uncoupled to oligomycin-inhibited endogenous respiration observed in intact fibroblasts, which pointed to a decrease with donor's age in the control of respiration by the mitochondrial membrane potential, the very significant decrease in efficiency of OX-PHOS, as determined by novel in situ measurements of P:O ratios, and, consistent with these results, the very significant reduction in the respiratory control ratios. These findings clearly pointed to a dramatic mitochondrial dysfunction, which would lead to a decrease in ATP synthesis rate, with the observed decline in mitochondrial protein synthesis rate being a likely contributing factor. These observations have important implications for understanding the biology of aging, as well as the pathogenesis of aging-related degenerative diseases.nesis of aging-related degenerative diseases.)
Sies 1997 Exp Physiol + (An imbalance between oxidants and antioxid … An imbalance between oxidants and antioxidants in favour of the oxidants, potentially leading to damage, is termed 'oxidative stress'. Oxidants are formed as a normal product of aerobic metabolism but can be produced at elevated rates under pathophysiological conditions. Antioxidant defense involves several strategies, both enzymatic and non-enzymatic. In the lipid phase, tocopherols and carotenes as well as oxy-carotenoids are of interest, as are vitamin A and ubiquinols. In the aqueous phase, there are ascorbate, glutathione and other compounds. In addition to the cytosol, the nuclear and mitochondrial matrices and extracellular fluids are protected. Overall, these low molecular mass antioxidant molecules add significantly to the defense provided by the enzymes superoxide dismutase, catalase and glutathione peroxidases.ase, catalase and glutathione peroxidases.)
Salin 2021 Mar Environ Res + (An important, but underappreciated, conseq … An important, but underappreciated, consequence of climate change is the reduction in crucial nutrient production at the base of the marine food chain: the long-chain omega-3 highly unsaturated fatty acids (n-3 HUFA). This can have dramatic consequences on consumers, such as fish as they have limited capacity to synthesise n-3 HUFA ''de novo''. The n-3 HUFA, such as docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3), are critical for the structure and function of all biological membranes. There is increasing evidence that fish will be badly affected by reductions in n-3 HUFA dietary availability, however the underlying mechanisms remain obscure. Hypotheses for how mitochondrial function should change with dietary n-3 HUFA availability have generally ignored ATP production, despite its importance to a cell's total energetics capacity, and in turn, whole-animal performance. Here we (i) quantified individual variation in mitochondrial efficiency (ATP/O ratio) of muscle and (ii) examined its relationship with content in EPA and DHA in muscle membrane of a primary consumer fish, the golden grey mullet ''Chelon auratus'', receiving either a high or low n-3 HUFA diet. Mitochondria of fish fed on the low n-3 HUFA diet had higher ATP/O ratio than those of fish maintained on the high n-3 HUFA diet. Yet, mitochondrial efficiency varied up about 2-fold among individuals on the same dietary treatment, resulting in some fish consuming half the oxygen and energy substrate to produce the similar amount of ATP than conspecific on similar diet. This variation in mitochondrial efficiency among individuals from the same diet treatment was related to individual differences in fatty acid composition of the membranes: a high ATP/O ratio was associated with a high content in EPA and DHA in biological membranes. Our results highlight the existence of interindividual differences in mitochondrial efficiency and its potential importance in explaining intraspecific variation in response to food chain changes.riation in response to food chain changes.)
Gnaiger 2015 Abstract MiP2015 + (An increasing number of metabolic and othe … An increasing number of metabolic and other diseases is recognized as being linked to mitochondrial physiology and dysfunction of oxidative phosphorylation ([[OXPHOS]]), which can be analyzed effectively and quantitatively by [[high-resolution respirometry]] (HRR). Instrumental quality control is a fundamental component of HRR applied in many laboratories [1]. Beyond the instrumental level, a standardized mt-laboratory quality management system (QMSmtf [2]) is required for establishing a global data base on mitochondrial function (mtf) in human cells and tissues, taking into account the variables of evolution, age, gender, life style and environment ([[MitoEAGLE]]). A QMSmtf requires the availability of a mt-reference sample which is functionally stable over time and across geographical space, as a basis of standard proficiency tests within and between reference laboratories. Mammalian mt-preparations (isolated mitochondria, tissue preparations) appear to be neither suitable for prolonged storage nor large scale production. Therefore, we focused on cryopreserved human cells [3]. Using the widely applied cell line HEK 293T we optimized cryopreservation to maintain cell viability and stabilize respiratory characteristics of intact and permeabilized cells over variable periods of time. HEK 293T cells were cultured under standard conditions with DMEM, were cryopreserved by cooling cells suspended in a freezing medium with fetal calf serum (FCS) and 10% dimethyl sulfoxide (DMSO), and stored at -80 °C for variable periods of time. Cells were thawed by addion of and careful mixing in pre-warmed PBS or MiR05. Cell counts and viability were assessed by determination of Trypan blue exclusion using an automated Countess cell counter. Respiration was measured in the Oroboros Oxygraph-2k applying standard substrate-uncoupler-inhibitor-titration ([[SUIT]]) protocols for permeabilized cells in [[MiR05]]. For HRR with intact cells, cyropreserved cells were suspended in pre-warmed DMEM. Results were compared with tests on cells cryopreserved with addition of the powerful antioxidant [[melatonin]] at 10 nM or 25 µM.[melatonin]] at 10 nM or 25 µM.)
Doerrier 2015 Abstract MiP2015 + (An increasing number of studies point to m … An increasing number of studies point to mitochondria as key regulators of many physiological and pathological conditions, related to life style (including physical exercise and nutrition), neurodegenerative diseases, metabolic disorders, inflammatory diseases, cancer, heart failure, and aging. Moreover, mitochondria are an important source of reactive oxygen species (ROS), which are needed for cell signaling. However, an increase in ROS production generates an oxidative stress which is implicated in the pathogenesis of many diseases. In particular, the NADH redox state is related to ROS production. Succinate is a substrate of succinate dehydrogenase (CII). For analysis of mitochondrial function with CII-linked substrates, rotenone (inhibitor of CI) is added to prevent accumulation of oxaloacetate (Oa), which is a strong competitive inhibitor of CII [1]. Ischaemic accumulation of succinate has been related to mitochondrial ROS production during reperfusion by reverse electron transfer [2]. In the present study, we used succinate with and without rotenone as a model for pathophysiological mitochondrial ROS-production.We investigated the effect of succinate (10 mM) alone, S, or succinate (10 mM) with rotenone (0.5 μM), S(Rot), on mitochondrial respiration, hydrogen peroxide (H2O2) production and NADH redox state in cardiac isolated mitochondria from C57BL/6 mice. Respiration media (37 °C) were optimized for the specific protocols. High-resolution respirometry (HRR) was applied with the O2k-Fluorometer (Oroboros , Innsbruck, Austria). H2O2 production was measured simultaneously using Amplex Ultrared [3]. NAD(P)H autofluorescence was monitored in a prototype NextGen-O2k, which combines HRR with O2k-Spectrofluorometry. Step changes of the fluorescence signal were calibrated with NADH and corrected for changes observed in chemical background tests. These methods allow analyzing simultaneously relevant bioenergetic parameters to assess mitochondrial function.Oxygen consumption levels were similar for S and S(Rot) in the LEAK state (without adenylates). However, H2O2 production was substantially higher with S in LEAK state. Adding ADP (2 mM) to S(Rot) to induce OXPHOS capacity, mitochondrial respiration increased by 70%. In contrast ADP titration to S induced a decline in respiration by 30% with respect to the LEAK state, which is the so-called “succinate paradox” [4].ed a decline in respiration by 30% with respect to the LEAK state, which is the so-called “succinate paradox” [4].)
Cagnone 2016 Sci Rep + (An increasing number of women fail to achi … An increasing number of women fail to achieve pregnancy due to either failed fertilization or embryo arrest during preimplantation development. This often results from decreased oocyte quality. Indeed, reduced mitochondrial DNA copy number (mitochondrial DNA deficiency) may disrupt oocyte quality in some women. To overcome mitochondrial DNA deficiency, whilst maintaining genetic identity, we supplemented pig oocytes selected for mitochondrial DNA deficiency, reduced cytoplasmic maturation and lower developmental competence, with autologous populations of mitochondrial isolate at fertilization. Supplementation increased development to blastocyst, the final stage of preimplantation development, and promoted mitochondrial DNA replication prior to embryonic genome activation in mitochondrial DNA deficient oocytes but not in oocytes with normal levels of mitochondrial DNA. Blastocysts exhibited transcriptome profiles more closely resembling those of blastocysts from developmentally competent oocytes. Furthermore, mitochondrial supplementation reduced gene expression patterns associated with metabolic disorders that were identified in blastocysts from mitochondrial DNA deficient oocytes. These results demonstrate the importance of the oocyte's mitochondrial DNA investment in fertilization outcome and subsequent embryo development to mitochondrial DNA deficient oocytes.nt to mitochondrial DNA deficient oocytes.)
Friederich 2017 Hum Mol Genet + (An infant presented with fatal infantile l … An infant presented with fatal infantile lactic acidosis and cardiomyopathy, and was found to have profoundly decreased activity of respiratory chain complex I in muscle, heart and liver. Exome sequencing revealed compound heterozygous mutations in NDUFB10, which encodes an accessory subunit located within the PD part of complex I. One mutation resulted in a premature stop codon and absent protein, while the second mutation replaced the highly conserved cysteine 107 with a serine residue. Protein expression of NDUFB10 was decreased in muscle and heart, and less so in the liver and fibroblasts, resulting in the perturbed assembly of the holoenzyme at the 830 kDa stage. NDUFB10 was identified together with three other complex I subunits as a substrate of the intermembrane space oxidoreductase CHCHD4 (also known as Mia40). We found that during its mitochondrial import and maturation NDUFB10 transiently interacts with CHCHD4 and acquires disulfide bonds. The mutation of cysteine residue 107 in NDUFB10 impaired oxidation and efficient mitochondrial accumulation of the protein and resulted in degradation of non-imported precursors. Our findings indicate that mutations in NDUFB10 are a novel cause of complex I deficiency associated with a late stage assembly defect and emphasize the role of intermembrane space proteins for the efficient assembly of complex I.s for the efficient assembly of complex I.)
SiouNing 2023 Molecules + (An infectious disease is the most apprehen … An infectious disease is the most apprehensive problem in aquaculture as it can lead to high mortality in aquatic organisms and massive economic loss. Even though significant progress has been accomplished in therapeutic, prevention, and diagnostic using several potential technologies, more robust inventions and breakthroughs should be achieved to control the spread of infectious diseases. MicroRNA (miRNA) is an endogenous small non-coding RNA that post-transcriptionally regulates the protein-coding genes. It involves various biological regulatory mechanisms in organisms such as cell differentiation, proliferation, immune responses, development, apoptosis, and others. Furthermore, an miRNA also acts as a mediator to either regulate host responses or enhance the replication of diseases during infection. Therefore, the emergence of miRNAs could be potential candidates for the establishment of diagnostic tools for numerous infectious diseases. Interestingly, studies have revealed that miRNAs can be used as biomarkers and biosensors to detect diseases, and can also be used to design vaccines to attenuate pathogens. This review provides an overview of miRNA biogenesis and specifically focuses on its regulation during infection in aquatic organisms, especially on the host immune responses and how miRNAs enhance the replication of pathogens in the organism. In addition to that, we explored the potential applications, including diagnostic methods and treatments, that can be employed in the aquaculture industry.n be employed in the aquaculture industry.)
Salvadego 2016 J Appl Physiol (1985) + (An integrative evaluation of oxidative met … An integrative evaluation of oxidative metabolism was carried out in 9 healthy young men (age, 24.1 ± 1.7 yr mean ± SD) before (CTRL) and after a 10-day horizontal bed rest carried out in normoxia (N-BR) or hypoxia (H-BR, FiO2 = 0.147). H-BR was designed to simulate planetary habitats. Pulmonary O2 uptake (''V''O2) and vastus lateralis fractional O2 extraction (changes in deoxygenated hemoglobin+myoglobin concentration, Δ[deoxy(Hb+Mb)] evaluated using near-infrared spectroscopy) were evaluated in normoxia and during an incremental cycle ergometer (CE) and one-leg knee extension (KE) exercise (aimed at reducing cardiovascular constraints to oxidative function). Mitochondrial respiration was evaluated ''ex vivo'' by high-resolution respirometry in permeabilized vastus lateralis fibers. During CE ''V''O2peak and Δ[deoxy(Hb+Mb)]peak were lower (''P'' < 0.05) after both N-BR and H-BR than during CTRL; during KE the variables were lower after N-BR but not after H-BR. During CE the overshoot of Δ[deoxy(Hb+Mb)] during constant work rate exercise was greater in N-BR and H-BR than CTRL, whereas during KE a significant difference vs. CTRL was observed only after N-BR. Maximal mitochondrial respiration determined ''ex vivo'' was not affected by either intervention. In N-BR, a significant impairment of oxidative metabolism occurred downstream of central cardiovascular O2 delivery and upstream of mitochondrial function, possibly at the level of the intramuscular matching between O2 supply and utilization and peripheral O2 diffusion. Superposition of hypoxia on bed rest did not aggravate, and partially reversed, the impairment of muscle oxidative function ''in vivo'' induced by bed rest. The effects of longer exposures will have to be determined.Copyright © 2016 the American Physiological Society.vivo'' induced by bed rest. The effects of longer exposures will have to be determined. Copyright © 2016 the American Physiological Society.)
CTCM 2019 Ankara TR + (An international symposium on cellular therapy in cardiovascular medicine (CTCM): stem cell opportunity, Ankara, Turkey, 2019)
Boardman 2020 Am J Physiol Heart Circ Physiol + (An ischemic insult is accompanied by an ac … An ischemic insult is accompanied by an acute increase in circulating fatty acid (FA), which can induce adverse changes related to cardiac metabolism/energetics. Although chronic hyperlipidemia contributes to the pathogenesis of obesity/diabetes-related cardiomyopathy, it unclear how these hearts are affected by an acute high FA-load. We hypothesize that adaptation to chronic FA exposure enhances the obese hearts' ability to handle an acute high FA-load. Diet-induced obese (DIO) and age-matched control (CON) mouse hearts were perfused in the presence of low or high FA-load (0.4 and 1.8 mM). Left ventricular (LV) function, FA oxidation rate, myocardial oxygen consumption and mechanical efficiency were assessed, followed by analysis of myocardial oxidative stress, mitochondrial respiration, protein acetylation as well as gene expression. Finally, ischemic tolerance was determined by examining LV functional recovery and infarct size. Under low FA conditions, DIO hearts showed mild LV dysfunction, oxygen wasting, mechanical inefficiency, and reduced mitochondrial OxPhos. High FA-load increased FA oxidation rates in both groups, but this did not alter any of the above parameters in DIO hearts. In contrast, CON hearts showed FA-induced mechanical inefficiency, oxidative stress and reduced OxPhos, as well as enhanced acetylation and activation of PPARα-dependent gene expression. While high FA-load did not alter functional recovery and infarct size in CON hearts, it increased ischemic tolerance in DIO hearts. Thus, this study demonstrates that acute FA-load affects normal and obese hearts differently, and that chronically elevated circulating FA levels render the DIO heart less vulnerable to the disadvantageous effects of an acute FA-load.sadvantageous effects of an acute FA-load.)
Haack 2010 Nat Genet + (An isolated defect of respiratory Complex … An isolated defect of respiratory Complex I activity is a frequent biochemical abnormality in mitochondrial disorders. Despite intensive investigation in recent years, in most instances, the molecular basis underpinning Complex I defects remains unknown. We report whole-exome sequencing of a single individual with severe, isolated Complex I deficiency. This analysis, followed by filtering with a prioritization of mitochondrial proteins, led us to identify compound heterozygous mutations in ACAD9, which encodes a poorly understood member of the mitochondrial acyl-CoA dehydrogenase protein family. We demonstrated the pathogenic role of the ACAD9 variants by the correction of the Complex I defect on expression of the wildtype ACAD9 protein in fibroblasts derived from affected individuals. ACAD9 screening of 120 additional Complex I-defective index cases led us to identify two additional unrelated cases and a total of five pathogenic ACAD9 alleles. a total of five pathogenic ACAD9 alleles.)
Wardle 2023 Issues Sci Technol + (An obsession with gauging accuracy of individual posts is misguided. To strengthen information ecosystems, focus on narratives and why people share what they do.)
Rodolphi 2017 Thesis + (Anabolic androgenic steroids (AAS) such as … Anabolic androgenic steroids (AAS) such as nandrolone decanoate (ND) are synthetic hormones derived from testosterone. It is known that one of the most important adverse effects of abusive administration of these steroids is the increase in aggressive behavior. Evidence indicates that high doses of AAS alter morphology and cause hyperactivation of glutamatergic synapses which correlates with an aggressive exacerbated phenotype. Physiologically, glutamate is considered the main excitatory neurotransmitter in the mammalian brain. At high glutamate levels, occurs neuronal hyperexcitability mainly through the ionotropic N-methyl-d-aspartate (NMDAr) type of glutamatergic receptors and, consequently, changes in mitochondrial metabolism. Existing transporters in astrocytes predominantly perform the termination of glutamatergic excitatory signaling. In this sense, the GLT-1 glutamate astrocytic transporter is responsible for more than 90% of glutamate removal from the synaptic cleft, contributing significantly to the maintenance of glutamatergic signaling homeostasis. Administration of the β-lactam antibiotic ceftriaxone (CEF) increases GLT-1 expression and decreases glutamatergic hyperexcitability, which could potentially counteract brain mechanisms associated to increased aggressive phenotype mediated by nandrolone decanoate (ND). However, a possible molecular and behavioral interaction has not yet been explored in context. Thus, the primary objective of this work was to investigate whether increased expression of the GLT-1 astrocyte transporter modulates the glutamatergic mechanisms involved in ND-induced aggressive phenotype, and mitochondrial activity. Sixty-day-old male CF-1 mice were divided into 4 groups: oil vehicle (VEH), nandrolone (ND), ceftriaxone (CEF) and nandrolone + ceftriaxone (ND / CEF). Nandrolone was injected subcutaneously (15mg / kg) for 19 days. Ceftriaxone (200mg / kg) or saline solution were administered intraperitoneally for 5 days. After the last injection, the latency for the first attack and the number of attacks on the intruder test were evaluated. The animals were sacrificed after the test, and homogeinized cortex were used for immunoquantification of GLT-1 and phosphorylation of the NMDAr pNR2Bser1232 subunit. Mitochondrial activity was evaluated in total brain sinaptossomes. Glutamate levels were measured in the cerebrospinal fluid. Compared to the vehicle group, treatment with ND significantly decreased the expression of GLT-1, increased glutamate levels and expression of the pNR2Bser1232 which was mechanistically associated with an increase in the aggressive phenotype; decrease in the latency and increase in the number of attacks. Also, ND decreased mitochondrial respiratory control. Administration of CEF significantly increased GLT-1 expression and decreased glutamate levels relative to the ND group, whereas pNR2Bser1232 levels and aggressive phenotype were similar to the control group. In the ND / CEF group the expression of GLT-1 and pNR2Bser1232, glutamate levels and aggressive phenotype were significantly lower than in the ND group, and similar to the control group. Furthermore, CEF was able to attenuate the alteration in the mitochondrial respiratory control caused by ND. Our results demonstrated that the levels of glutamate astrocytic transporter GLT-1 and pNR2Bser1232 are important mechanism behind the increased aggressive phenotype induced by ND, and decreased mitochondrial respiratory control. Also, this model reinforces the importance of glutamate levels and astrocytic molecular targets in the regulation of the aggressive phenotype.ce of glutamate levels and astrocytic molecular targets in the regulation of the aggressive phenotype.)
Putzer 1985 Comp Biochem Physiol + (Anaerobic processes were studied in ''Tubi … Anaerobic processes were studied in ''Tubifex'' and other aquatic invertebrates. After the aerobic-anoxic transition of Tubifex, succinate accumulated up to about 25 μmol/g Wd within the first hour of anoxia, but steady-state levels were established after 4hr at only 10 μmol/g Wd in an open-flow system.Proprionate accumulated after a lag of 30 min and reached steady-state concentrations of about 30 μmol/g Wd after 5 h of anoxia.Lactate concentrations did not increase above 4 μmol/g Wd under anoxia. Its accumulation was not induced by exposure to a blood extract, although ''Tubifex'' has the potential for lactate production.The initial rates of glycolytic endproduct accumulation were increased in the presence of the deproteinized blood extract by 60% (succinate, 0–30 min anoxia) and by 50% and 90% (proprionate, 30–60 min anoxia; 1% and 2% blood extract, respectively). The maximum and steady state levels of these metabolites were not influenced by the hydrolysate of blood.Aerobic and anaerobic heat dissipation of ''Lumbriculus variegatus'' was stimulated by the addition to the medium of a deproteinized hydrolysate of bovine blood. Oxygen uptake of ''Cyclops abyssorum'' increased similarly upon the addition of the blood extract under hypoxia.lops abyssorum'' increased similarly upon the addition of the blood extract under hypoxia.)
Keys 2014 Int J Epidemiol + (Analyses are reported on the correlation w … Analyses are reported on the correlation with height and with subcutaneous fat thickness of relative weight expressed as per cent of average weight at given height, and of the ratios weight/height, weight/height squared, and the ponderal index (cube root of weight divided by height) in 7424 ‘healthy’ men in 12 cohorts in five countries. Analyses are also reported on the relationship of those indicators of relative weight to body density in 180 young men and in 248 men aged 49–59. Judged by the criteria of correlation with height (lowest is best) and to measures of body fatness (highest is best), the ponderal index is the poorest of the relative weight indices studied. The ratio of weight to height squared, here termed the body mass index, is slightly better in these respects than the simple ratio of weight to height. The body mass index seems preferable over other indices of relative weight on these grounds as well as on the simplicity of the calculation and, in contrast to percentage of average weight, the applicability to all populations at all times.icability to all populations at all times.)
Kuznetsov 2008 Nat Protoc + (Analysis of mitochondrial function is cent … Analysis of mitochondrial function is central to the study of intracellular energy metabolism, mechanisms of cell death and pathophysiology of a variety of human diseases, including myopathies, neurodegenerative diseases and cancer. However, important properties of mitochondria differ ''in vivo'' and ''in vitro''. Here, we describe a protocol for the analysis of functional mitochondria ''in situ'', without the isolation of organelles, in selectively permeabilized cells or muscle fibers using digitonin or saponin. A specially designed substrate/inhibitor titration approach allows the step-by-step analysis of several mitochondrial complexes. This protocol allows the detailed characterization of functional mitochondria in their normal intracellular position and assembly, preserving essential interactions with other organelles. As only a small amount of tissue is required for analysis, the protocol can be used in diagnostic settings in clinical studies. The permeabilization procedure and specific titration analysis can be completed in 2 h.itration analysis can be completed in 2 h.)
Doerrier 2016 Mitochondrion + (Analysis of mitochondrial function is cruc … Analysis of mitochondrial function is crucial to understand their involvement in a given disease. High-resolution respirometry of permeabilized myocardial fibers in septic mice allows the evaluation of the bioenergetic system, maintaining mitochondrial ultrastructure and intracellular interactions, which are critical for an adequate functionality. OXPHOS and electron transport system (ET-pathway) capacities were assessed using different substrate combinations. Our findings show severe septic-dependent impairment in OXPHOS and ET capacities with mitochondrial uncoupling at early and late phases of sepsis. Moreover, sepsis triggers complex III (CIII)-linked alterations in supercomplexes structure, and loss of mitochondrial density. In these conditions, melatonin administration to septic mice prevented sepsis-dependent mitochondrial injury in mitochondrial respiration. Likewise, melatonin improved cytochrome b content and ameliorated the assembly of CIII in supercomplexes. These results support the use of permeabilized fibers to identify properly respiratory deficits and specific melatonin effects in sepsis. and specific melatonin effects in sepsis.)
Analytica China 2020 Shanghai CN + (Analytica China Exhibition, Shanghai, China, 2020)
Bousseau 2019 FASEB J + (Angiogenesis is a complex process leading … Angiogenesis is a complex process leading to the growth of new blood vessels from existing vasculature, triggered by local proangiogenic factors such as VEGF. An excess of angiogenesis is a recurrent feature of various pathologic conditions such as tumor growth. Phostines are a family of synthetic glycomimetic compounds that exhibit anticancer properties, and the lead compound 3-hydroxy-4,5-bis-benzyloxy-6-benzyloxymethyl-2-phenyl2-oxo-2λ5-[1,2]oxaphosphinane (PST 3.1a) shows antiglioblastoma properties both ''in vitro'' and ''in vivo''. In the present study, we assessed the effect of PST 3.1a on angiogenesis and endothelial metabolism. ''In vitro'', PST 3.1a (10 µM) inhibited all steps that regulate angiogenesis, including migration, proliferation, adhesion, and tube formation. ''In vivo'', PST 3.1a reduced intersegmental vessel formation and vascularization of the subintestinal plexus in zebrafish embryos and also altered pathologic angiogenesis and glioblastoma progression ''in vivo''. Mechanistically, PST 3.1a altered interaction of VEGF receptor 2 and glycosylation-regulating protein galectin-1, a key component regulating angiogenesis associated with tumor resistance. Thus, these data show that use of PST 3.1a is an innovative approach to target angiogenesis.nnovative approach to target angiogenesis.)
Atallah 2022 Biomedicines + (Angiogenesis is an essential process by wh … Angiogenesis is an essential process by which new blood vessels develop from existing ones. While adequate angiogenesis is a physiological process during, for example, tissue repair, insufficient and excessive angiogenesis stands on the pathological side. Fine balance between pro- and anti-angiogenic factors in the tissue environment regulates angiogenesis. Identification of these factors and how they function is a pressing topic to develop angiogenesis-targeted therapeutics. During the last decade, exciting data highlighted non-metabolic functions of intermediates of the mitochondrial Krebs cycle including succinate. Among these functions is the contribution of succinate to angiogenesis in various contexts and through different mechanisms. As the concept of targeting metabolism to treat a wide range of diseases is rising, in this review we summarize the mechanisms by which succinate regulates angiogenesis in normal and pathological settings. Gaining a comprehensive insight into how this metabolite functions as an angiogenic signal will provide a useful approach to understand diseases with aberrant or excessive angiogenic background, and may provide strategies to tackle them.and may provide strategies to tackle them.)
Chergova 2015 Abstract MiPschool London 2015 + (Angiogenesis is the process of new blood v … Angiogenesis is the process of new blood vessel formation from preexisting vasculature [1]. Endothelial cells (ECs) are responsible for the development of the vascular plexus. This process is very active during embryonic development whereas ECs are quiescent during adulthood. Reactivation of angiogenesis is related to various pathological states such as tumor growth. Angiogenesis requires remodeling and new tissue formation and therefore a higher demand in ATP. Mitochondria are essential cell organelles with pivotal role in processes of life and death and they are the main source of ATP in the cell. Nevertheless, it has been shown that VEGF, a key pro-angiogenic factor, is involved in mitochondrial biogenesis [2]. However, the role of mitochondria in the endothelium is poorly understood. Mitochondria are extremely dynamic structures. Their morphology is modulated through processes of fusion and fission in order to fulfill their diverse functions [3]. Mitochondrial morphology is orchestrated by a number of dynamin-like GTPases. Mitochondrial fusion depends on mitofusin 1 (MFN1), mitofusin 2 (MFN2) and Optic Atrophy 1 (OPA1). DRP1 is the key regulator of mitochondrial fission. The emerging of mitochondrial function in diverse cellular processes provoked our interest to study mitochondrial dynamics and the role of DRP1 in endothelial cells during angiogenesis.''In vitro'' we are approaching DRP1’s function in HUVEC cells (Human Umbilical Cord Endothelial Cells) under angiogenic stimulation or ablation. ''In vivo'' we will evaluate physiological angiogenesis using the mouse retinal neovascularization model [4] in the conditional endothelial knock out for DRP1.Our results show that VEGF treatment of HUVECs decreases DRP1 levels. Parallel to this inhibition of angiogenesis by the anti-angiogenic factor 16K prolactin causes an increase of DRP1 expression. Furthermore, we evaluated angiogenesis by measuring cell migration, proliferation and permeability in HUVECs with down-regulation of DRP1 (siRNAs) and we observed an upregulation of angiogenic parameters.Our preliminary data are suggesting a key role of mitochondrial dynamics in angiogenesis and a new function for DRP1 in endothelial cells. Our goal is to identify how pro and anti-angiogenic agents affect DRP1 and which are the molecular pathways through which DRP1 is affecting angiogenesis.ough which DRP1 is affecting angiogenesis.)
Kivelae 2014 EMBO Mol Med + (Angiogenic growth factors have recently be … Angiogenic growth factors have recently been linked to tissue metabolism. We have used genetic gain- and loss-of function models to elucidate the effects and mechanisms of action of vascular endothelial growth factor-B (VEGF-B) in the heart. A cardiomyocyte-specific VEGF-B transgene induced an expanded coronary arterial tree and reprogramming of cardiomyocyte metabolism. This was associated with protection against myocardial infarction and preservation of mitochondrial complex I function upon ischemia-reperfusion. VEGF-B increased VEGF signals via VEGF receptor-2 to activate Erk1/2, which resulted in vascular growth. Akt and mTORC1 pathways were upregulated and AMPK downregulated, readjusting cardiomyocyte metabolic pathways to favor glucose oxidation and macromolecular biosynthesis. However, contrasting with a previous theory, there was no difference in fatty acid uptake by the heart between the VEGF-B transgenic, gene-targeted or wildtype rats. Importantly, we also show that VEGF-B expression is reduced in human heart disease. Our data indicate that VEGF-B could be used to increase the coronary vasculature and to reprogram myocardial metabolism to improve cardiac function in ischemic heart disease.ardiac function in ischemic heart disease.)
Vorotnikov 2022 Biomedicines + (Angiopathy is a common complication of dia … Angiopathy is a common complication of diabetes mellitus. Vascular endothelium is among the first targets to experience blood-borne metabolic alterations, such as hyperglycemia and hyperlipidemia, the hallmarks of type 2 diabetes. To explore mechanisms of vascular dysfunction and eventual damage brought by these pathologic conditions and to find ways to protect vasculature in diabetic patients, various research approaches are used including in vitro endothelial cell-based models. We present an analysis of the data available from these models that identifies early endothelial cell apoptosis associated with oxidative stress as the major outcome of mimicking hyperglycemia and hyperlipidemia in vitro. However, the fate of endothelial cells observed in these studies does not closely follow it in vivo where massive endothelial damage occurs mainly in the terminal stages of diabetes and in conjunction with comorbidities. We propose that the discrepancy is likely in missing essentials that should be available to cultured endothelial cells to adjust the metabolic state and withstand the immediate apoptosis. We discuss the role of carnitine, creatine, and AMP-activated protein kinase (AMPK) in suiting the endothelial metabolism for long-term function in diabetic type milieu in vitro. Engagement of these essentials is anticipated to expand diabetes research options when using endothelial cell-based models. when using endothelial cell-based models.)
Havird 2019 Mitochondrion + (Angiosperm mitochondrial (mt) genes are ge … Angiosperm mitochondrial (mt) genes are generally slow-evolving, but multiple lineages have undergone dramatic accelerations in rates of nucleotide substitution and extreme changes in mt genome structure. While molecular evolution in these lineages has been investigated, very little is known about their mt function. Some studies have suggested altered respiration in individual taxa, although there are several reasons why mt variation might be neutral in others. Here, we develop a new protocol to characterize respiration in isolated plant mitochondria and apply it to species of ''Silene'' with mt genomes that are rapidly evolving, highly fragmented, and exceptionally large (~11 Mbp). This protocol, complemented with traditional measures of plant fitness, cytochrome c oxidase activity assays, and fluorescence microscopy, was also used to characterize inter- and intraspecific variation in mt function. Contributions of the individual "classic" OXPHOS complexes, the alternative oxidase, and external NADH dehydrogenases to overall mt respiratory flux were found to be similar to previously studied angiosperms with more typical mt genomes. Some differences in mt function could be explained by inter- and intraspecific variation. This study suggests that ''Silene'' species with peculiar mt genomes still show relatively normal mt respiration. This may be due to strong purifying selection on mt variants, coevolutionary responses in the nucleus, or a combination of both. Future experiments should explore such questions using a comparative framework and investigating other lineages with unusual mitogenomes.Copyright © 2019 Elsevier B.V. and Mitochondria Research Society. All rights reserved.a Research Society. All rights reserved.)
Havird 2018 bioRxiv + (Angiosperm mitochondrial (mt) genes are ge … Angiosperm mitochondrial (mt) genes are generally slow-evolving, but multiple lineages have undergone dramatic accelerations in rates of nucleotide substitution and extreme changes in mt genome structure. While molecular evolution in these lineages has been investigated, very little is known about their mt function. Here, we develop a new protocol to characterize respiration in isolated plant mitochondria and apply it to species of ''Silene'' with mt genomes that are rapidly evolving, highly fragmented, and exceptionally large (~11 Mbp). This protocol, complemented with traditional measures of plant fitness, cytochrome c oxidase activity assays, and fluorescence microscopy, was used to characterize inter- and intraspecific variation in mt function. Contributions of the individual "classic" OXPHOS complexes, the alternative oxidase, and external NADH dehydrogenases to overall mt respiratory flux were found to be similar to previously studied angiosperms with more typical mt genomes. Some differences in mt function could be explained by inter- and intraspecific variation, possibly due to local adaptation or environmental effects. Although this study suggests that these ''Silene'' species with peculiar mt genomes still show relatively normal mt function, future experiments utilizing the protocol developed here can explore such questions in a more detailed and comparative framework.a more detailed and comparative framework.)
Liu 2016 Apoptosis + (Angiotensin II (AngII) is an important fac … Angiotensin II (AngII) is an important factor that promotes the proliferation of cancer cells, whereas celastrol exhibits a significant antitumor activity in various cancer models. Whether celastrol can effectively suppress AngII mediated cell proliferation remains unknown. In this study, we studied the effect of celastrol on AngII-induced HepG2 cell proliferation and evaluated its underlying mechanism. The results revealed that AngII was able to significantly promote HepG2 cell proliferation via up-regulating AngII type 1 (AT1) receptor expression, improving mitochondrial respiratory function, enhancing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, increasing the levels of reactive oxygen species (ROS) and pro-inflammatory cytokines. The excess ROS from mitochondrial dysfunction is able to cause the apoptosis of tumor cells via activating caspase3 signal pathway. In addition, the reaction between NO and ROS results in the formation of peroxynitrite (ONOO-), and then promoting cell damage. Celastrol dramatically enhanced ROS generation, thereby causing cell apoptosis through inhibiting mitochodrial respiratory function and boosting the expression levels of AngII type 2 (AT2) receptor without influencing NADPH oxidase activity. PD123319 as a special inhibitor of AT2R was able to effectively decrease the levels of inflammatory cytokines and endothelial nitric oxide synthase (eNOS) activity, but only partially attenuate the effect of celastrol on AnII mediated HepG2 cell proliferation. Thus, celastrol has the potential for use in liver cancer therapy. ROS derived from mitochondrial is an important factor for celastrol to suppress HepG2 cell proliferation.ial is an important factor for celastrol to suppress HepG2 cell proliferation.)
Menze 2009 J Biol Chem + (Anhydrobiotic animals survive virtually co … Anhydrobiotic animals survive virtually complete loss of cellular water. The mechanisms that explain this phenomenon are not fully understood but often include the accumulation of low molecular weight solutes such as trehalose and macromolecules like Late Embryogenesis Abundant (LEA) proteins. Here we report for the first time the occurrence of a mitochondria-targeted LEA gene (Afrlea3m) product in an animal species. The deduced molecular mass of the 307-amino acid polypeptide from the brine shrimp ''Artemia franciscana'' is 34 kDa. Bioinformatic analyses reveal features typical of a Group 3 LEA protein, and subcellular localization programs predict targeting of the mature peptide to the mitochondrial matrix, based on an N-terminal, amphipathic presequence. Real-time quantitative PCR shows that ''Afralea3m'' mRNA is expressed manyfold higher in desiccation-tolerant embryonic stages when compared with intolerant nauplius larvae. Mitochondrial localization of the protein was confirmed by transfection of human hepatoma cells (HepG2/C3A) with a nucleotide construct encoding the first 70 N-terminal amino acids of ''AfrLEA3m'' in-frame with the nucleotide sequence for green fluorescence protein. The chimeric protein was readily incorporated into mitochondria of these cells. Successful targeting of a protein to human mitochondria by use of an arthropod signaling sequence clearly reveals the highly conserved nature of such presequences, as well as of the import machinery. Finally, mitochondria isolated from A. franciscana embryos, which naturally contain ''AfrLEA3m'' and trehalose, exhibit resistance to water stress (freezing) as evidenced by an unchanged capacity for oxidative phosphorylation on succinate + rotenone, a resistance that is absent in mammalian mitochondria lacking AfrLEA3m.n mammalian mitochondria lacking AfrLEA3m.)
Zhang 2022 Mol Med Rep + (Animal models for Parkinson's disease (PD) … Animal models for Parkinson's disease (PD) are very useful in understanding the pathogenesis of PD and screening for new therapeutic approaches. The present study compared two commonly used neurotoxin‑induced mouse models of chronic PD to guide model selection, explore the pathogenesis and mechanisms underlying PD and develop effective treatments. The chronic PD mouse models were established via treatment with rotenone or 1‑methyl‑4‑phenyl‑1,2,3,6-tetrahydropyridine (MPTP) for 6 weeks. The effects of rotenone and MPTP in the mice were compared by assessing neurobehavior, neuropathology and mitochondrial function through the use of the pole, rotarod and open field tests, immunohistochemistry for tyrosine hydroxylase (TH), glial fibrillary acidic protein (GFAP), ionized calcium‑binding adapter molecule 1 (Iba‑1), neuronal nuclear antigen (NeuN) and (p)S129 α‑synuclein, immunofluorescence for GFAP, Iba‑1 and NeuN, western blotting for TH, oxygen consumption, complex I enzyme activity. The locomotor activity, motor coordination and exploratory behavior in both rotenone and MPTP groups were significantly lower compared with the control group. However, behavioral tests were no significant differences between the two groups. In the MPTP group, the loss of dopaminergic (DA) neurons in the substantia nigra (SN) pars compacta, the reduction of the tyrosine hydroxylase content in the SN and striatum and the astrocyte proliferation and microglial activation in the SN were more significant compared with the rotenone group. Notably, mitochondrial‑dependent oxygen consumption and complex I enzyme activity in the SN were significantly reduced in the rotenone group compared with the MPTP group. In addition, Lewy bodies were present only in SN neurons in the rotenone group. Although no significant differences in neurobehavior were observed between the two mouse models, the MPTP model reproduced the pathological features of PD more precisely in terms of the loss of DA neurons, decreased dopamine levels and neuroinflammation in the SN. On the other hand, the rotenone model was more suitable for studying the role of mitochondrial dysfunction (deficient complex I activity) and Lewy body formation in the SN, which is a characteristic pathological feature of PD. The results indicated that MPTP and rotenone PD models have advantages and disadvantages, therefore one or both should be selected based on the purpose of the study.elected based on the purpose of the study.)
Tsilidis 2013 PLOS Biol + (Animal studies generate valuable hypothese … Animal studies generate valuable hypotheses that lead to the conduct of preventive or therapeutic clinical trials. We assessed whether there is evidence for excess statistical significance in results of animal studies on neurological disorders, suggesting biases. We used data from meta-analyses of interventions deposited in Collaborative Approach to Meta-Analysis and Review of Animal Data in Experimental Studies (CAMARADES). The number of observed studies with statistically significant results (O) was compared with the expected number (E), based on the statistical power of each study under different assumptions for the plausible effect size. We assessed 4,445 datasets synthesized in 160 meta-analyses on Alzheimer disease (n = 2), experimental autoimmune encephalomyelitis (n = 34), focal ischemia (n = 16), intracerebral hemorrhage (n = 61), Parkinson disease (n = 45), and spinal cord injury (n = 2). 112 meta-analyses (70%) found nominally (p≤0.05) statistically significant summary fixed effects. Assuming the effect size in the most precise study to be a plausible effect, 919 out of 4,445 nominally significant results were expected versus 1,719 observed (p<10−9). Excess significance was present across all neurological disorders, in all subgroups defined by methodological characteristics, and also according to alternative plausible effects. Asymmetry tests also showed evidence of small-study effects in 74 (46%) meta-analyses. Significantly effective interventions with more than 500 animals, and no hints of bias were seen in eight (5%) meta-analyses. Overall, there are too many animal studies with statistically significant results in the literature of neurological disorders. This observation suggests strong biases, with selective analysis and outcome reporting biases being plausible explanations, and provides novel evidence on how these biases might influence the whole research domain of neurological animal literature.rch domain of neurological animal literature.)
Lau 2017 Dissertation + (Animals are highly dependent on oxygen (O& … Animals are highly dependent on oxygen (O2). The use of O2, however, comes with both advantages and disadvantages. On one hand, O2 is key to the process that produces chemical energy within mitochondria inside the cell, on the other hand the use of O2 generates reactive oxygen species (ROS), which are harmful byproducts. In this thesis, I investigated these two aspects of O2 use at mitochondria from a group of sculpin fishes that are distributed along the marine intertidal zone and are naturally exposed to daily fluctuations of O2. I found that more hypoxia tolerant sculpins improved O2 binding at the level of mitochondria. However, this increased O2 binding was not associated with increased aerobic energy production, and counterintuitively, there was higher ROS generation in more hypoxia tolerant sculpins. It is possible that higher ROS generation in hypoxia tolerant sculpins is part of the strategy in surviving the O2 variable intertidal.ssible that higher ROS generation in hypoxia tolerant sculpins is part of the strategy in surviving the O2 variable intertidal.)
Tian 2017 Front Genet + (Animals that are able to sustain life unde … Animals that are able to sustain life under hypoxic conditions have long captured the imagination of biologists and medical practitioners alike. Although the associated morphological modifications have been extensively described, the mechanisms underlying the evolution of hypoxia tolerance are not well understood. To provide such insights, we investigated genes in four major energy metabolism pathways, and provide evidence of distinct evolutionary paths to mammalian hypoxia-tolerance. Positive selection of genes in the oxidative phosphorylation pathway mainly occurred in terrestrial hypoxia-tolerant species; possible adaptations to chronically hypoxic environments. The strongest candidate for positive selection along cetacean lineages was the citrate cycle signaling pathway, suggestive of enhanced aerobic metabolism during and after a dive. Six genes with cetacean-specific amino acid changes are rate-limiting enzymes involved in the gluconeogenesis pathway, which would be expected to enhance the lactate removal after diving. Intriguingly, 38 parallel amino acid substitutions in 29 genes were observed between hypoxia-tolerant mammals. Of these, 76.3% were radical amino acid changes, suggesting that convergent molecular evolution drives the adaptation to hypoxic stress and similar phenotypic changes. This study provides further insights into life under low oxygen conditions and the evolutionary trajectories of hypoxia-tolerant species. trajectories of hypoxia-tolerant species.)
Salin 2016 J Exp Biol + (Animals, especially ectotherms, are highly … Animals, especially ectotherms, are highly sensitive to the temperature of their surrounding environment. Extremely high temperature, for example, induces a decline of average performance of conspecifics within a population, but individual heterogeneity in the ability to cope with elevating temperatures has rarely been studied. In this study, we examined inter-individual variation in feeding ability and consequent growth rate of juvenile brown trout Salmo trutta acclimated to a high temperature (19°C), and investigated the relationship between these metrics of whole-animal performances and among-individual variation in mitochondrial respiration capacity. Food was provided ''ad libitum'' yet intake varied ten-fold amongst individuals, resulting in some fish losing weight whilst others continued to grow. Almost half of the variation in food intake was related to variability in mitochondrial capacity: low intake (and hence growth failure) was associated with high LEAK respiration rates within liver and muscle mitochondria, and a lower coupling of muscle mitochondria. These observations, combined with the inability of fish with low food consumption to increase their intake despite ''ad libitum'' food levels, suggest a possible insufficient capacity of the mitochondria for maintaining ATP homeostasis. Individual variation in thermal performance is likely to confer variation in the upper limit of an organism's thermal niche and in turn affect the structure of wild populations in warming environments.© 2016. Published by The Company of Biologists Ltd.ublished by The Company of Biologists Ltd.)
ESCI 2014 + (Annual Scientific Meeting of the European Society for Clinical Investigation , Utrecht, The Netherlands; [http://www.esci.eu.com/meetings/ ESCI 2014])
Ravasz 2024 Sci Rep + (Anoxia halts oxidative phosphorylation (OX … Anoxia halts oxidative phosphorylation (OXPHOS) causing an accumulation of reduced compounds in the mitochondrial matrix which impedes dehydrogenases. By simultaneously measuring oxygen concentration, NADH autofluorescence, mitochondrial membrane potential and ubiquinone reduction extent in isolated mitochondria in real-time, we demonstrate that Complex I utilized endogenous quinones to oxidize NADH under acute anoxia. 13C metabolic tracing or untargeted analysis of metabolites extracted during anoxia in the presence or absence of site-specific inhibitors of the electron transfer system showed that NAD+ regenerated by Complex I is reduced by the 2-oxoglutarate dehydrogenase Complex yielding succinyl-CoA supporting mitochondrial substrate-level phosphorylation (mtSLP), releasing succinate. Complex II operated amphidirectionally during the anoxic event, providing quinones to Complex I and reducing fumarate to succinate. Our results highlight the importance of quinone provision to Complex I oxidizing NADH maintaining glutamate catabolism and mtSLP in the absence of OXPHOS.bolism and mtSLP in the absence of OXPHOS.)
Komlodi 2018b EBEC2018 + (Anoxia leads to over-reduction of mitochon … Anoxia leads to over-reduction of mitochondrial coenzyme Q (Q, quinone) pools rendering Complex I unable to oxidize NADH, leading to a profound decrease in the matrix NAD+/NADH ratio. As a consequence, the function of matrix dehydrogenases is impaired. Yet, under certain anoxic conditions catabolism of metabolites converging through the α-ketoglutarate dehydrogenase Complex (KGDHC) is known to occur, yielding succinyl-CoA, in turn supporting substrate-level phosphorylation substantiated by succinate-CoA ligase [1].Mitochondrial respiration and NADH autofluorescence were measured simultaneously with the NextGen-O2k (Oroboros Instruments, Innsbruck, Austria), and the redox state of the Q-pool was detected with a three-electrode system implanted into the O2k (Oroboros Q2k).We show that in isolated mouse liver mitochondria Complex I utilizes endogenous quinones oxidizing NADH during anoxia. Untargeted metabolomic analysis of matrix metabolites of mitochondria subjected to respiratory arrest due to anoxia and in the presence of specific inhibitors of respiratory complexes infer showed that NAD+ arising from Complex I is utilized by KGDHC yielding succinyl-CoA for succinate-CoA ligase, thus maintaining substrate-level phosphorylation during anoxia. Finally, by using custom-made 3D-printed plugs designed for standard fluorometric cuvettes, we show that under no conditions of respiratory arrest due to anoxia and/or pharmacological inhibition of the complexes did the mitochondria undergo swelling, which could potentially confound matrix metabolite estimations or bioenergetic parameters due to permeability transition.Our results highlight the importance of the availability of quinones in conjunction with the operation of Complex I in maintaining substrate-level phosphorylation during anoxia.ex I in maintaining substrate-level phosphorylation during anoxia.)
Ravasz 2019 Abstract IOC141 + (Anoxia leads to over-reduction of mitochon … Anoxia leads to over-reduction of mitochondrial quinone pools hampering Complex I from oxidizing NADH, leading to a profound decrease in the matrix NAD+/NADH ratio. As a consequence of this, the function of matrix dehydrogenases is impaired. Yet, under certain anoxic conditions catabolism of metabolites converging through the ketoglutarate dehydrogenase complex (KGDHC) is known to occur yielding succinyl-CoA, in turn supporting substrate-level phosphorylation substantiated by succinate-CoA ligase. Here, by measuring simultaneously oxygen partial pressure and NADH autofluorescence or quinone redox state we show that in isolated mitochondria Complex I utilizes endogenous quinones oxidizing NADH during anoxia. Untargeted metabolomic analysis of matrix metabolites of anoxic mitochondria and in the presence of ETS inhibitors inferred that NAD+ arising from Complex I is utilized by KGDHC yielding succinyl-CoA for succinate-CoA ligase, thus maintaining substrate-level phosphorylation during anoxia. The amount of endogenous quinones was estimated to be in the millimolar range and was unaffected by dietary intake of vitamin K3 (menadione). The quinone pools could be reduced by Complexes I and II and the electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) system during anoxia, exhibiting a descending order of affinity and reciprocally, increasing order of capacity. Our results highlight the importance of quinone availability in conjunction to Complex I-mediated NADH oxidation in maintaining substrate-level phosphorylation during anoxia.trate-level phosphorylation during anoxia.)
Ravasz 2018 Abstract The evolving concept of mitochondria + (Anoxia leads to over-reduction of mitochon … Anoxia leads to over-reduction of mitochondrial quinone pools hampering Complex I from oxidizing NADH, leading to a profound decrease in the matrix NAD+/NADH ratio. As a consequence of this, the function of matrix dehydrogenases is impaired. Yet, under certain anoxic conditions catabolism of metabolites converging through the ketoglutarate dehydrogenase Complex (KGDHC) is known to occur yielding succinyl-CoA, in turn supporting substrate-level phosphorylation substantiated by succinate-CoA ligase. Here, by measuring simultaneously oxygen partial pressure and NADH autofluorescence or quinone redox state we show that in isolated mitochondria Complex I utilizes endogenous quinones oxidizing NADH during anoxia. Untargeted metabolomic analysis of matrix metabolites of anoxic mitochondria and in the presence of ETC inhibitors inferred that NAD+ arising from Complex I is utilized by KGDHC yielding succinyl-CoA for succinate-CoA ligase, thus maintaining substrate-level phosphorylation during anoxia. The amount of endogenous quinones was estimated to be in the millimolar range and was unaffected by dietary intake of vitamin K3 (menadione). The quinone pools could be reduced by Complexes I and II and the electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) system during anoxia, exhibiting a descending order of affinity and reciprocally, increasing order of capacity. Our results highlight the importance of quinone availability in conjunction to Complex I-mediated NADH oxidation in maintaining substrate-level phosphorylation during anoxia.trate-level phosphorylation during anoxia.)
Buck 2012 Adv Exp Med Biol + (Anoxia rapidly elicits hyper-excitability … Anoxia rapidly elicits hyper-excitability and cell death in mammal brain but this is not so in anoxia-tolerant turtle brain where spontaneous electrical activity is suppressed by anoxia (i.e. spike arrest; SA). In anoxic turtle brain extracellular GABA concentrations increase dramatically and impact GABAergic synaptic transmission in a way that results in SA. Here we briefly review what is known about the regulation of glutamatergic signalling during anoxia and investigate the possibility that in anoxic turtle cortical neurons GABA(A/B) receptors play an important role in neuroprotection. Both AMPA and NMDA receptor currents decrease by about 50% in anoxic turtle cerebrocortex and therefore exhibit channel arrest, whereas GABA-A receptor currents increase twofold and increase whole-cell conductance. The increased post synaptic GABA-A receptor current is contrary to the channel arrest hypothesis but it does serve an important function. The reversal potential of the GABA-A receptor (E(GABA)) is only slightly depolarized relative to the resting membrane potential of the neuron and not sufficient to elicit an action potential. Therefore, when GABA-A receptors are activated, membrane potential moves to E(GABA) and prevents further depolarization by glutamatergic inputs during anoxia by a process termed shunting inhibition. Furthermore we discuss the presynaptic role of GABA-B receptors and show that increased endogenous GABA release during anoxia mediates SA by activating both GABA-A and B receptors and that this represents a natural oxygen-sensitive adaptive mechanism to protect brain from anoxic injury.anism to protect brain from anoxic injury.)
Gnaiger 1987 Physiol Zool + (Anoxic heat dissipation of ''Lumbriculus v … Anoxic heat dissipation of ''Lumbriculus variegatus'', as measured by direct calorimetry, is reduced by up to 85 % relative to aerobic rates. The decrease of anoxic heat dissipation and the diminution of activity peaks in the calorimetric output coincide with the disappearance of peristaltic movements under anoxia. A transfer from aerobic conditions with food to anoxia without food results in cessation of defecation when the gut is half emptied, whereas the gut is completely emptied under aerobic conditions within 6 and 8-10 h at 20 and 11 °C, respectively. The aerobic retention time of the food is independent of worm length (10-50 mm). After aerobic feeding the gut content is higher than after anoxic feeding at 6 °C. On return to aerobic conditions, heat dissipation increases immediately, whereas defecation is resumed only after a lag of 2 h. An anoxic component to the aerobic heat dissipation becomes apparent in relation to simultaneous respirometric measurements when feces accumulate in the calorimetric chamber. When the guts are completely emptied before the experiment, the theoretical oxycaloric equivalent yields an accurate estimate of heat dissipation, indicating that no significant net formation of anoxic end products occurs under aerobic conditions. Anoxic catabolism of glycogen may not fully explain the directly measured rates of heat dissipation under environmental anoxia. This has been suggested earlier for ''Lumbriculus'' and has since been confirmed for ''Tubifex'' on the basis of simultaneous calorimetric and biochemical measurements. Direct calorimetry is required to assess total rates of metabolic energy expenditure in anoxic oligochaetes.energy expenditure in anoxic oligochaetes.)
Martinez 2013 Marine Biol + (Antarctic fauna are highly adapted to the … Antarctic fauna are highly adapted to the frigid waters of the Southern Ocean. This study describes the ''in vitro'' temperature sensitivity of oxygen consumption rates measured in liver mitochondria from the pelagic notothenioid ''Pleuragramma antarcticum'' between 5 and 35 °C. Oxygen fluxes were measured after the addition of millimolar levels of pyruvate, malate, succinate and glutamate (LEAK) and saturating levels of ADP [oxidative phosphorylation (OXPHOS)]. OXPHOS respiration significantly decreased above 18.7 °C. A comparison of the oxidative capacities among ''P. antarcticum'' and other notothenioids showed significant differences in OXPHOS respiration, where benthic species exhibited about 50% lower OXPHOS capacities than ''P. antarcticum''. In addition, OXPHOS capacities normalized per milligram of mitochondrial protein of ''P''. antarcticum'' were up to eight times higher than those reported in the literature for other notothenioids. The comparatively high respiration rates measured in this study may be explained by our approach, which engaged both Complexes I and II under conditions of oxidative phosphorylation. OXPHOS capacities of independently activated Complexes I and II were found to range from 42 to 100% of rates obtained when both complexes were activated simultaneously in the same species. The remarkable tolerance of ''P. antarcticum'' OXPHOS toward warmer temperatures was unexpected for an Antarctic stenotherm and may indicate that thermal sensitivity of their mitochondria is not the driving force behind their stenothermy.he driving force behind their stenothermy.)
Strobel 2013 PLoS One + (Antarctic notothenioid fish are characteri … Antarctic notothenioid fish are characterized by their evolutionary adaptation to the cold, thermostable Southern Ocean, which is associated with unique physiological adaptations to withstand the cold and reduce energetic requirements but also entails limited compensation capacities to environmental change. This study compares the capacities of mitochondrial acclimation to ocean warming and acidification between the Antarctic nototheniid ''Notothenia rossii'' and the sub-Antarctic ''Lepidonotothen squamifrons'', which share a similar ecology, but different habitat temperatures. After acclimation of ''L. squamifrons'' to 9 °C and ''N. rossii'' to 7 °C (normocapnic/hypercapnic, 0.2 kPa CO2/2000 ppm CO2) for 4-6 weeks, we compared the capacities of their mitochondrial respiratory complexes I (CI) and II (CII), their P/O ratios (phosphorylation efficiency), proton leak capacities and mitochondrial membrane fatty acid compositions. Our results reveal reduced CII respiration rates in warm-acclimated ''L. squamifrons'' and cold hypercapnia-acclimated ''N. rossii''. Generally, ''L. squamifrons'' displayed a greater ability to increase CI contribution during acute warming and after warm-acclimation than N. rossii. Membrane unsaturation was not altered by warm or hypercapnia-acclimation in both species, but membrane fatty acids of warm-acclimated ''L. squamifrons'' were less saturated than in warm normocapnia-/hypercapnia-acclimated ''N. rossii''. Proton leak capacities were not affected by warm or hypercapnia-acclimation of ''N. rossii''. We conclude that an acclimatory response of mitochondrial capacities may include higher thermal plasticity of CI supported by enhanced utilization of anaplerotic substrates (via oxidative decarboxylation reactions) feeding into the citrate cycle. ''L. squamifrons'' possesses higher relative CI plasticities than N. rossii, which may facilitate the usage of energy efficient NADH-related substrates under conditions of elevated energy demand, possibly induced by ocean warming and acidification. The observed adjustments of electron transport system complexes with a higher flux through CI under warming and acidification suggest a metabolic acclimation potential of the sub-Antarctic ''L. squamifrons'', but only limited acclimation capacities for ''N. rossii''. acclimation capacities for ''N. rossii''.)
Skemiene 2020 J Bioenerg Biomembr + (Anthocyanins are considered as bioactive c … Anthocyanins are considered as bioactive components of plant-based diets that provide protection against ischemic cardiovascular pathologies by mechanisms dependent on their antioxidant and reductive capacities. However, it is not clear whether similar anthocyanin-mediated mechanisms can provide protection against ischemia-induced brain mitochondrial injury and cell death. In this study, we compared effects of three cyanidin-3-glycosides - glucoside (Cy3G), galactoside (Cy3Gal) and rutinoside (Cy3R), with pelargonxidin-3-glucoside (Pg3G) and found that at 10-20 μM concentrations they have no direct effect on respiratory functions of mitochondria isolated from normal or ischemia-damaged rat brain slices. However, intravenous injection of Cy3Gal and Cy3G (0,025 mg/kg or 0,05 mg/kg what matches 10 μM or 20 μM respectively) but not Cy3R in rats protected against ischemia-induced caspase activation and necrotic cell death, and reduced infarct size in cerebral cortex and cerebellum. These effects correlated with cytochrome c reducing capacity of cyanidin-3-glycosides. In contrast, intravenous injection of 0,025 mg/kg Pg3G which has the lowest cytochrome c reducing capacity among investigated anthocyanins, had no effect on ischemia-induced caspase activation and necrosis but reduced brain infarct size whereas intravenous injection of 0,05 mg/kg of Pg3G slightly promoted necrosis in the brain. Our data suggest that reductive rather than antioxidant capacities of anthocyanins may be important components in providing protection against ischemic brain damage. protection against ischemic brain damage.)
Skemiene 2015 FEBS J + (Anthocyanins, a subclass of flavonoids, ar … Anthocyanins, a subclass of flavonoids, are known to protect against myocardial ischemia; however, little is known about their direct, acute effects on mitochondria injured by the ischemic insult. In this study, the effects of delphinidin 3-O-glucoside (Dp3G), cyanidin 3-O-glucoside (Cy3G) and pelargonidin 3-O-glucoside (Pg3G) on the activity of complex I of the mitochondrial respiratory chain were studied in mitochondria isolated from normal rat hearts and rat hearts subjected to ischemia for 45 min. Cy3G and Dp3G increased the activity of complex I, measured in the presence or absence of coenzyme Q1 (CoQ1 ), in ischemia-damaged mitochondria, whereas in nonischemic mitochondria the effect was observed only in the absence of CoQ1. Dp3G and Cy3G but not Pg3G increased state 3 respiration and ATP synthesis with NADH-dependent substrates in mitochondria after ischemia. The results suggest that certain anthocyanins can act as electron acceptors at complex I, and bypass ischemia-induced inhibition, resulting in increased ATP production after ischemia. This study provides new information on a possible role of certain anthocyanins in the regulation of energy metabolism in mammalian cells.ertain anthocyanins in the regulation of energy metabolism in mammalian cells.)
Jirkovsky 2012 J Pharmacol Exp Ther + (Anthracycline anticancer drugs (e.g., doxo … Anthracycline anticancer drugs (e.g., doxorubicin or daunorubicin) can induce chronic cardiotoxicity and heart failure (HF), both of which are believed to be based on oxidative injury and mitochondrial damage. In this study, molecular and functional changes induced by chronic anthracycline treatment with progression into HF in post-treatment follow-up were analyzed with special emphasis on nuclear factor erythroid 2-related factor 2 (Nrf2) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) pathways. Chronic cardiotoxicity was induced in rabbits with daunorubicin (3 mg/kg, weekly for 10 weeks), and the animals were followed for another 10 weeks. Echocardiography revealed a significant drop in left ventricular (LV) systolic function during the treatment with marked progression to LV dilation and congestive HF in the follow-up. Although daunorubicin-induced LV lipoperoxidation was found, it was only loosely associated with cardiac performance. Furthermore, although LV oxidized glutathione content was increased, the oxidized-to-reduced glutathione ratio itself remained unchanged. Neither Nrf2, the master regulator of antioxidant response, nor the majority of its target genes showed up-regulation in the study. However, down-regulation of manganese superoxide dismutase and NAD(P)H dehydrogenase [quinone] 1 were observed together with heme oxygenase 1 up-regulation. Although marked perturbations in mitochondrial functions were found, no induction of PGC1α-controlled mitochondrial biogenesis pathway was revealed. Instead, especially in the post-treatment period, an impaired regulation of this pathway was observed along with down-regulation of the expression of mitochondrial genes. These results imply that global oxidative stress need not be a factor responsible for the development of anthracycline-induced HF, whereas suppression of mitochondrial biogenesis might be involved.itochondrial biogenesis might be involved.)
Govender 2015 Abstract MiPschool Cape Town 2015 + (Anthracyclines, such as doxorubicin (DXR), … Anthracyclines, such as doxorubicin (DXR), are among the most valuable treatments for various cancers, but their clinical use is limited due to detrimental side-effects such as cardiotoxicity. DXR-induced cardiotoxicity is emerging as a critical issue among cancer survivors and is an area of much significance to the field of cardio-oncology. The abundance of mitochondria in cardiomyocytes closely links mitochondrial bioenergetics with myocardial function and viability [1]. It has been demonstrated that DXR specifically targets mitochondria and increases the generation of reactive oxygen species (ROS), decreases adenosine triphosphate (ATP) production and modulates mitochondrial sirtuin activity; thus, mitochondrial dysfunction has recently been recognized as a pivotal element in the development of DXR-induced cardiotoxicity [2]. In light of this scenario, both endogenously produced and exogenously administered melatonin during or prior chemotherapy shows great promise in this therapeutic avenue as demonstrated in various studies [3]. MLT is a potent anti-oxidant, is non-toxic, is dually oncostatic and cardio-protective, and has been shown to influence mitochondrial homeostasis and function [3,4]. Although a number of studies support the mitochondrial protective role of MLT, the exact mechanisms by which MLT confers mitochondrial protection in the context of DXR-induced cardiotoxicity remain to be elucidated. This study evaluated the role of MLT on mitochondrial function, mitochondrial dynamics and cell death during DXR-induced cardiotoxicity. H9C2 rat cardiac myoblasts were pre-treated with MLT (10 µM) for 24h followed by DXR treatment (3 µM) for 24h. Following treatment, mitochondrial reductive capacity and apoptotic cell death were assessed. Mitochondrial bioenergetic parameters was analysed using the XF96 analyser (extracellular flux). These results indicate a significant decrease in mitochondrial reductive capacity in response to DXR treatment versus the control (38.88 ± 0.3435 % vs 100%, ''p''< 0.0001). Cells pre-treated with MLT followed by DXR treatment showed a significant increase in mitochondrial reductive capacity versus the DXR treated group only (97.45 ± 0.3733 % vs 38.88 ± 0.3435 %, ''p''< 0.0001). Furthermore, a significant decrease in caspase 3/7 activity was detected when cells were pre-treated with MLT followed by DXR treatment versus the DXR treated group only (1.649 ± 0.084 fold vs 2.307± 0.1035 fold, ''p''< 0.001). ATP turnover was significantly increased when cells were pre-treated with MLT followed by DXR treatment versus the DXR treated group only (48.39 ± 3.797 % vs 64.43 ± 2.670 %, ''p''< 0.001). These results strongly indicate that pre-treatment with MLT confers a mitochondrial cardioprotective effect during DXR-induced cardiotoxicity by significantly increasing cardiac myocytes viability and influencing mitochondrial bioenergetics.viability and influencing mitochondrial bioenergetics.)
Jose 2018 Redox Biol + (Anti-cancer effects of local anesthetics h … Anti-cancer effects of local anesthetics have been reported but the mode of action remains elusive. Here, we examined the bioenergetic and REDOX impact of levobupivacaine on human prostate cancer cells (DU145) and corresponding non-cancer primary human prostate cells (BHP). Levobupivacaine induced a combined inhibition of glycolysis and oxidative phosphorylation in cancer cells, resulting in a reduced cellular ATP production and consecutive bioenergetic crisis, along with reactive oxygen species generation. The dose-dependent inhibition of respiratory chain complex I activity by levobupivacaine explained the alteration of mitochondrial energy fluxes. Furthermore, the potency of levobupivacaine varied with glucose and oxygen availability as well as the cellular energy demand, in accordance with a bioenergetic anti-cancer mechanism. The levobupivacaine-induced bioenergetic crisis triggered cytostasis in prostate cancer cells as evidenced by a S-phase cell cycle arrest, without apoptosis induction. In DU145 cells, levobupivacaine also triggered the induction of autophagy and blockade of this process potentialized the anti-cancer effect of the local anesthetic. Therefore, our findings provide a better characterization of the REDOX mechanisms underpinning the anti-effect of levobupivacaine against human prostate cancer cells.Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.ed by Elsevier B.V. All rights reserved.)
Gouspillou 2015 Sci Rep + (Anticancer treatments for childhood acute … Anticancer treatments for childhood acute lymphoblastic leukaemia (ALL) are highly effective but are now implicated in causing impaired muscle function in long-term survivors. However, no comprehensive assessment of skeletal muscle mitochondrial functions in long-term survivors has been performed and the presence of persistent chemotherapy-induced skeletal muscle mitochondrial dysfunction remains a strong possibility. Non-tumour-bearing mice were treated with two drugs that have been used frequently in ALL treatment (doxorubicin and dexamethasone) for up to 4 cycles at 3-week intervals and euthanized 3 months after the 4th cycle. Treated animals had impaired growth and lower muscle mass as well as reduced mitochondrial respiration and increased reactive oxygen species production per unit oxygen consumption. Mitochondrial DNA content and protein levels of key mitochondrial membrane proteins and markers of mitochondrial biogenesis were unchanged, but protein levels of Parkin were reduced. This suggests a novel pattern of chemotherapy-induced mitochondrial dysfunction in skeletal muscle that persists because of an acquired defect in mitophagy signaling. The results could explain the observed functional impairments in adult survivors of childhood ALL and may also be relevant to long-term survivors of other cancers treated with similar regimes.ther cancers treated with similar regimes.)
Lotkova 2011 Gen Physiol Biophys + (Antiinflammatory effect of statins mediate … Antiinflammatory effect of statins mediated by the reduction of cytokine IL-6 in hepatocytes have been reported. Contrary to beneficial effect, statins can increase susceptibility to mitochondrial dysfunction. Extrahepatic biliary obstruction is associated with oxidative stress, pro-inflammatory response and hepatocyte mitochondrial dysfunction. The aim of our study was to verify the effect of fluvastatin on cholestatic liver injury. Cholestasis was induced in Wistar rats by bile duct ligation. Fluvastatin (1 or 5 mg/kg) was administered after surgery and then daily for 7 days. The dose of 5 mg/kg led to the deterioration of hepatocellular injury. Despite lower production of IL-6, decrease in GSH content, rise of TGFß and inhibition of respiratory complex I in mitochondria were determined. The mRNA expressions of canalicular transporter Mdr1b and basolateral transporter Mrp3 increased in cholestatic liver. Fluvastatin administration then led to the attenuation of this change. Analogously, mRNA expression of conjugative enzyme Ugt1a1 was diminished by fluvastatin administration to cholestatic rats. We can conclude that decrease in the antioxidative status and mitochondrial dysfunction could at least in part participate on the deteriorating effect of fluvastatin. Whether these processes can be a consequence of the alteration in metabolism and transport of potentially toxic substances remains to verify.tially toxic substances remains to verify.)
James 2005 J Biol Chem + (Antioxidants, such as ubiquinones, are wid … Antioxidants, such as ubiquinones, are widely used in mitochondrial studies as both potential therapies and useful research tools. However, the effects of exogenous ubiquinones can be difficult to interpret because they can also be pro-oxidants or electron carriers that facilitate respiration. Recently we developed a mitochondria-targeted ubiquinone (MitoQ10) that accumulates within mitochondria. MitoQ10 has been used to prevent mitochondrial oxidative damage and to infer the involvement of mitochondrial reactive oxygen species in signaling pathways. However, uncertainties remain about the mitochondrial reduction of MitoQ10, its oxidation by the respiratory chain, and its pro-oxidant potential. Therefore, we compared MitoQ analogs of varying alkyl chain lengths (MitoQn, n = 3-15) with untargeted exogenous ubiquinones. We found that MitoQ10 could not restore respiration in ubiquinone-deficient mitochondria because oxidation of MitoQ analogs by complex III was minimal. Complex II and glycerol 3-phosphate dehydrogenase reduced MitoQ analogs, and the rate depended on chain length. Because of its rapid reduction and negligible oxidation, MitoQ10 is a more effective antioxidant against lipid peroxidation, peroxynitrite and superoxide. Paradoxically, exogenous ubiquinols also autoxidize to generate superoxide, but this requires their deprotonation in the aqueous phase. Consequently, in the presence of phospholipid bilayers, the rate of autoxidation is proportional to ubiquinol hydrophilicity. Superoxide production by MitoQ10 was insufficient to damage aconitase but did lead to hydrogen peroxide production and nitric oxide consumption, both of which may affect cell signaling pathways. Our results comprehensively describe the interaction of exogenous ubiquinones with mitochondria and have implications for their rational design and use as therapies and as research tools to probe mitochondrial function.rch tools to probe mitochondrial function.)
Viall 2013 J Autoimmun + (Antiphospholipid antibodies (aPL) are the … Antiphospholipid antibodies (aPL) are the strongest maternal risk factor for pre-eclampsia, a hypertensive disease of human pregnancy. Pre-eclampsia is triggered by a toxic factor released from the placenta that activates the maternal endothelium. Antiphospholipid antibodies cause the release of necrotic trophoblast debris from the placental syncytiotrophoblast and this debris can activate endothelial cells. In this study, we investigated how aPL affects syncytiotrophoblast death and production of necrotic trophoblast debris by examining the interaction between aPL and human first trimester placental explants. Human polyclonal and murine monoclonal aPL, but not control antibodies, were rapidly internalised by the syncytiotrophoblast. Inhibitors of endocytosis or the low-density lipoprotein receptor (LDLR) family, but not toll-like receptors, decreased the internalisation of aPL and prevented the release of necrotic trophoblast debris from the syncytiotrophoblast. Once internalised, aPL increased inner mitochondrial membrane leak and Cytochrome c release while depressing oxidative flux through Complex IV of the electron transport system in syncytiotrophoblast mitochondria. These data suggest that the human syncytiotrophoblast internalises aPL by antigen-dependent endocytosis involving LDLR family members. Once internalised by the syncytiotrophoblast, aPL affects the death-regulating mitochondria, causing extrusion of necrotic trophoblast debris which can activate maternal endothelial cells thereby contributing to the pathogenesis of pre-eclampsia.ting to the pathogenesis of pre-eclampsia.)
Quast 2022 Basic Res Cardiol + (Aortic valve stenosis (AS) is the most fre … Aortic valve stenosis (AS) is the most frequent valve disease with relevant prognostic impact. Experimental model systems for AS are scarce and comprehensive imaging techniques to simultaneously quantify function and morphology in disease progression are lacking. Therefore, we refined an acute murine AS model to closely mimic human disease characteristics and developed a high-resolution magnetic resonance imaging (MRI) approach for simultaneous in-depth analysis of valvular, myocardial as well as aortic morphology/pathophysiology to identify early changes in tissue texture and critical transition points in the adaptive process to AS. AS was induced by wire injury of the aortic valve. Four weeks after surgery, cine loops, velocity, and relaxometry maps were acquired at 9.4 T to monitor structural/functional alterations in valve, aorta, and left ventricle (LV). ''In vivo'' MRI data were subsequently validated by histology and compared to echocardiography. AS mice exhibited impaired valve opening accompanied by significant valve thickening due to fibrotic remodelling. While control mice showed bell-shaped flow profiles, AS resulted not only in higher peak flow velocities, but also in fragmented turbulent flow patterns associated with enhanced circumferential strain and an increase in wall thickness of the aortic root. AS mice presented with a mild hypertrophy but unaffected global LV function. Cardiac MR relaxometry revealed reduced values for both T1 and T2 in AS reflecting subtle myocardial tissue remodelling with early alterations in mitochondrial function in response to the enhanced afterload. Concomitantly, incipient impairments of coronary flow reserve and myocardial tissue integrity get apparent accompanied by early troponin release. With this, we identified a premature transition point with still compensated cardiac function but beginning textural changes. This will allow interventional studies to explore early disease pathophysiology and novel therapeutic targets.ophysiology and novel therapeutic targets.)
Wojewoda MiP2010 + (Apart from generally recognised role as AT … Apart from generally recognised role as ATP generators, mitochondria are also main reactive oxygen species (ROS) producers in the cells. Since we found that ROS level was altered in human NARP cells linked to NARP (Neuropathy, Ataxia and Retinitis Pigmentosa) syndrome and Rho0 cells [1], we hypothesised that ROS are implicated in regulation of mitochondrial biogenesis. We also used antioxidant (sodium selenite, 70 nM) that decreased ROS level in these cells [1] to establish to what extent these changes depended on ROS-mediated retrograde communication. Cell lines: human osteosarcoma cell lines: wild type (WT) cell line, cybrid cells (NARP) with default ATP synthase (mtDNA point mutation in subunit 6 of ATP synthase) and cells lacking mtDNA (Rho0). Laser scanning cytometry: ROS level, mitochondrial mass. Western blotting: the level of transcription factors and respiratory subunits; the level of respiratory subunits corresponds with the level of appropriate respiratory complexes since the chosen subunits are labile when their complexes are not assembled. Confocal imaging: localisation of NRF2 phosphorylated at Ser 40. Respiration: oxygen consumption measured with Clark type oxygen electrodeNuclear respiratory factors 1 and 2 (NRF1 and NRF2) are major regulators of respiratory gene expression. We found that the level of NRF1 was increased in NARP and Rho0 cells when compared with WT control. Selenium supplementation lead to further increase in NRF1 level. Since an increase in Akt/Protein kinase B phosphorylation at serine 473 (pAkt (Ser473)) was associated with activation of NRF1 transcriptional activity [2], we also assessed the level of pAkt (Ser473) in these cells. Subsequently, we established the activity of NRF2 (measured by its phosphorylation at serine 40 and found it altered in NARP and Rho0 cells. Comparison of pNRF2 (Ser 40) level with total level of NRF2 revealed that its activity was enhanced in cell lines with mtDNA defects. Moreover, we found that selenite further increased NRF2 phosphorylation. mtDNA defects in NARP and Rho0 cells also triggered adaptive changes at the level of respiratory subunits which were upregulated in NARP but downregulated in Rho0 cells. Selenite lowered the level of some respiratory subunits in WT and NARP cells without affecting their respiratory capacity.In cells with mtDNA defects the retrograde communication from mitochondria to nucleus modulates adaptive changes in mitochondrial biogenesis at the level of respiratory chain complexes via affecting nuclear respiratory factors. Because selenite supplementation affected both the level/activity of NRFs and the level of some respiratory subunits, we show that ROS play a significant role in the regulation of mitochondrial biogenesis.1. Wojewoda M, Duszyński J, Szczepanowska J (2010) Antioxidant defence systems and generation of reactive oxygen species in osteosarcoma cells with defective mitochondria; effect of selenium. Biochim. Biophys. Acta [doi:10.1016/j.bbabio.2010.01.035]2. Piantadosi CA, Suliman HB (2006) Mitochondrial transcription factor A induction by redox activation of nuclear respiratory factor 1. J. Biol. Chem. 281 324-333.tory factor 1. J. Biol. Chem. 281 324-333.)
Ratcliffe 2022 Clin Med (Lond) + (Apart from giving an overview of the findi … Apart from giving an overview of the findings themselves and their role in physiological oxygen homeostasis, I'd like to highlight the twists and turns of the experimental work, in particular the way that knowledge builds on knowledge in unexpected ways. Abraham Flexner, the US educationist, wrote a famous essay in the early twentieth century on the ‘usefulness of useless knowledge’.1 I'd like to paraphrase Flexner by emphasising the ‘importance of incomplete knowledge’. Our politicians are impatient for the utility of knowledge, perhaps not unreasonably, and our editors, perhaps less reasonably, are so often concerned with its completeness. Of course, most in tonight's audience will know that neither qualification of knowledge is valid. But nevertheless, I wish to emphasise the concerns I have, in case, in the face of societal or government impatience, or even that of our own peers, we lose our way.ience, or even that of our own peers, we lose our way.)
Ajime 2020 Nicotine Tob Res + (Apart from its adverse effects on the resp … Apart from its adverse effects on the respiratory system, cigarette smoking also induces skeletal muscle atrophy and dysfunction. Whether short-term smoking cessation can restore muscle mass and function is unknown. We therefore studied the impact of 1- and 2-weeks smoking cessation on skeletal muscles in a mouse model.Male mice were divided into 4 groups: Air-exposed (14 weeks); cigarette smoke (CS)-exposed (14 weeks); CS-exposed (13 weeks) followed by 1-week cessation; CS-exposed (12 weeks) followed by 2 weeks cessation to examine exercise capacity, physical activity levels, body composition, muscle function, capillarization, mitochondrial function and protein expression in the soleus, plantaris and diaphragm muscles.CS-induced loss of body and muscle mass was significantly improved within 1 week of cessation due to increased lean and fat mass. Mitochondrial respiration and protein levels of the respiratory complexes in the soleus were lower in CS-exposed mice, but similar to control values after 2 weeks of cessation. Exposing isolated soleus muscles to CS extracts reduced mitochondrial respiration that was reversed after removing the extract. While physical activity was reduced in all groups, exercise capacity, limb muscle force, fatigue resistance, fiber size and capillarization and diaphragm cytoplasmic HIF-1α were unaltered by CS-exposure. However, CS-induced diaphragm atrophy and increased capillary density was not seen after 2 weeks of smoking cessation.In male mice, two weeks smoking cessation reversed smoking-induced mitochondrial dysfunction, limb muscle mass loss and diaphragm muscle atrophy, highlighting immediate benefits of cessation on skeletal muscles.© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: [email protected].se e-mail: [email protected].)
Gomez-Valades 2021 Cell Metab + (Appropriate cristae remodeling is a determ … Appropriate cristae remodeling is a determinant of mitochondrial function and bioenergetics and thus represents a crucial process for cellular metabolic adaptations. Here, we show that mitochondrial cristae architecture and expression of the master cristae-remodeling protein OPA1 in proopiomelanocortin (POMC) neurons, which are key metabolic sensors implicated in energy balance control, is affected by fluctuations in nutrient availability. Genetic inactivation of OPA1 in POMC neurons causes dramatic alterations in cristae topology, mitochondrial Ca2+ handling, reduction in alpha-melanocyte stimulating hormone (α-MSH) in target areas, hyperphagia, and attenuated white adipose tissue (WAT) lipolysis resulting in obesity. Pharmacological blockade of mitochondrial Ca2+ influx restores α-MSH and the lipolytic program, while improving the metabolic defects of mutant mice. Chemogenetic manipulation of POMC neurons confirms a role in lipolysis control. Our results unveil a novel axis that connects OPA1 in POMC neurons with mitochondrial cristae, Ca2+ homeostasis, and WAT lipolysis in the regulation of energy balance.t;/sup> homeostasis, and WAT lipolysis in the regulation of energy balance.)
Cortassa 2019 Front Physiol + (Appropriate substrate selection between fa … Appropriate substrate selection between fats and glucose is associated with the success of interventions that maintain health such as exercise or caloric restriction, or with the severity of diseases such as diabetes or other metabolic disorders. Although the interaction and mutual inhibition between glucose and fatty-acids (FAs) catabolism has been studied for decades, a quantitative and integrated understanding of the control and regulation of substrate selection through central catabolic pathways is lacking. We addressed this gap here using a computational model representing cardiomyocyte catabolism encompassing glucose (Glc) utilization, pyruvate transport into mitochondria and oxidation in the tricarboxylic acid (TCA) cycle, β-oxidation of palmitate (Palm), oxidative phosphorylation, ion transport, pH regulation, and ROS generation and scavenging in cytoplasmic and mitochondrial compartments. The model is described by 82 differential equations and 119 enzymatic, electron transport and substrate transport reactions accounting for regulatory mechanisms and key players, namely pyruvate dehydrogenase (PDH) and its modulation by multiple effectors. We applied metabolic control analysis to the network operating with various Glc to Palm ratios. The flux and metabolites' concentration control were visualized through heat maps providing major insights into main control and regulatory nodes throughout the catabolic network. Metabolic pathways located in different compartments were found to reciprocally control each other. For example, glucose uptake and the ATP demand exert control on most processes in catabolism while TCA cycle activities and membrane-associated energy transduction reactions exerted control on mitochondrial processes namely β-oxidation. PFK and PDH, two highly regulated enzymes, exhibit opposite behavior from a control perspective. While PFK activity was a main rate-controlling step affecting the whole network, PDH played the role of a major regulator showing high sensitivity (elasticity) to substrate availability and key activators/inhibitors, a trait expected from a flexible substrate selector strategically located in the metabolic network. PDH regulated the rate of Glc and Palm consumption, consistent with its high sensitivity toward AcCoA, CoA, and NADH. Overall, these results indicate that the control of catabolism is highly distributed across the metabolic network suggesting that fuel selection between FAs and Glc goes well beyond the mechanisms traditionally postulated to explain the glucose-fatty-acid cycle.d to explain the glucose-fatty-acid cycle.)
Scattolin 2016 Abstract Mito Xmas Meeting Innsbruck + (Approximately 20% of T-cell acute lymphobl … Approximately 20% of T-cell acute lymphoblastic leukemia (T-ALL) patients do not respond to current therapy, and their clinical outcome is dismal.In the present study we show that leukemic cells isolated from T-ALL patients as well as cell lines stabilized ''in vitro'' or propagated ''in vivo'' as xenografts exhibit high levels of mitochondrial reactive oxygen species (ROS). Interestingly, raising mitochondrial ROS using NS1619, a small molecule that opens the mitochondrial BK K+ channel, induced death of leukemic cells from T-ALL patients and T-ALL cell lines but not of primary normal thymocytes or PBMC. These effects were enhanced by blunting ROS-scavenging pathways with dehydroepiandrosterone (DHEA), an inhibitor of the pentose phosphate pathway (PPP). The combination of NS1619 and DHEA led to proteolytic processing of OPA1, an inner mitochondrial membrane protein that controls cristae remodeling, cytochrome c release and apoptosis. OPA1 cleavage was dependent upon both ROS and the OMA1 mitochondrial protease. Furthermore, OPA1 cleavage induced by treatment with NS1619 and DHEA primed T-ALL cells to apoptosis induced by TNF-Related Apoptosis Inducing Ligand (TRAIL).These findings suggest that engaging the OMA1-OPA1 axis by raising mitochondrial ROS may prove to be an effective strategy for apoptotic priming of refractory T-ALL, which poses a major clinical challenge at present.LL, which poses a major clinical challenge at present.)
Silic-Benussi 2016a Abstract Mito Xmas Meeting Innsbruck + (Approximately 20% of T-cell acute lymphobl … Approximately 20% of T-cell acute lymphoblastic leukemia (T-ALL) patients do not respond to current therapy, and their clinical outcome is dismal. The PI3K/Akt/mTOR oncogenic pathway is commonly found hyper-activated in T-ALL. In addition to controlling cell growth and autophagy, mTORC1 influences mitochondrial activity and oxidative metabolism by controlling the interaction between YY1 and PGC1.In previous studies, we showed that T-ALL cells exhibit high levels of mitochondrial reactive oxygen species (ROS). ROS are powerful signalling molecules that can induce apoptosis through p53 activation, but may also increase cancer cell survival through PTEN oxidation, which results in an increased Akt activity. In the present study, we aimed at testing the possible cross-talk between mTOR and ROS in T-ALL. Interestingly, ''in vitro'' studies revealed that the mTORC1-inhibitor Everolimus increased ROS levels and induced cell death both in T-ALL cell lines and patient-derived T-ALL xenografts (PDTALL) but not in primary normal thymocytes. In addition, Everolimus increased the dexamethasone sensitivity of the glucocorticoid-resistant PDTALL19 ''in vitro''. The finding that Everolimus-induced cell death was reduced by pre-treatment with the ROS scavenger N-acetyl-cystein (NAC) indicates that this effect was ROS-dependen. ''In vivo'' experiments carried out using PDTALL cells showed that Everolimus significantly reduced the number of leukemic cells and increased the survival of treated-mice. These studies indicate a connection between mTOR and ROS, and suggest that mTORC1 inhibition may prove to be effective to overcome dexamethasone-resistance of refractory T-ALL patients.e-resistance of refractory T-ALL patients.)
Antona 2022 Cancers (Basel) + (Approximately 50% of colorectal cancer (CR … Approximately 50% of colorectal cancer (CRC) patients still die from recurrence and metastatic disease, highlighting the need for novel therapeutic strategies. Drug repurposing is attracting increasing attention because, compared to traditional ''de novo'' drug discovery processes, it may reduce drug development periods and costs. Epidemiological and preclinical evidence support the antitumor activity of antipsychotic drugs. Herein, we dissect the mechanism of action of the typical antipsychotic spiperone in CRC. Spiperone can reduce the clonogenic potential of stem-like CRC cells (CRC-SCs) and induce cell cycle arrest and apoptosis, in both differentiated and CRC-SCs, at clinically relevant concentrations whose toxicity is negligible for non-neoplastic cells. Analysis of intracellular Ca2+ kinetics upon spiperone treatment revealed a massive phospholipase C (PLC)-dependent endoplasmic reticulum (ER) Ca2+ release, resulting in ER Ca2+ homeostasis disruption. RNA sequencing revealed unfolded protein response (UPR) activation, ER stress, and induction of apoptosis, along with IRE1-dependent decay of mRNA (RIDD) activation. Lipidomic analysis showed a significant alteration of lipid profile and, in particular, of sphingolipids. Damage to the Golgi apparatus was also observed. Our data suggest that spiperone can represent an effective drug in the treatment of CRC, and that ER stress induction, along with lipid metabolism alteration, represents effective druggable pathways in CRC.h lipid metabolism alteration, represents effective druggable pathways in CRC.)
Ikaga 2015 Biochem Biophys Rep + (Aquaporin-8 (AQP8), a member of the aquapo … Aquaporin-8 (AQP8), a member of the aquaporin water channel family, is expressed in various tissue and cells, including liver, testis, and pancreas. AQP8 appears to have functions on the plasma membrane and/or on the mitochondrial inner membrane. Mitochondrial AQP8 with permeability for water, H2O2 and NH3 has been expected to have important role in various cells, but its information is limited to a few tissues and cells including liver and kidney. In the present study, we found that AQP8 was expressed in the mitochondria in mouse adipose tissues and 3T3-L1 preadipocytes, and investigated its role by suppressing its gene expression.AQP8-knocked down (shAQP8) cells were established using a vector expressing short hairpin RNA. Cellular localization of AQP8 was examined by western blotting and immunocytochemistry. Mitochondrial function was assessed by measuring mitochondrial membrane potential, oxygen consumption and ATP level measurements.In 3T3-L1 cells, AQP8 was expressed in the mitochondria. In shAQP8 cells, mRNA and protein levels of AQP8 were decreased by about 75%. The shAQP8 showed reduced activities of complex IV and ATP synthase; it is probable that the impaired mitochondrial water handling in shAQP8 caused suppression of the electron transport and ADP phosphorylation through inhibition of the two steps which yield water. The reduced activities of the last two steps of oxidative phosphorylation in shAQP8 cause low routine and maximum capacity of respiration and mitochondrial hyperpolarization.Mitochondrial AQP8 contributes to mitochondrial respiratory function probably through maintenance of water homeostasis.The AQP8-knocked down cells we established provides a model system for the studies on the relationships between water homeostasis and mitochondrial function.ies on the relationships between water homeostasis and mitochondrial function.)
Thoral 2023 J Exp Biol + (Aquatic ecosystems can exhibit seasonal va … Aquatic ecosystems can exhibit seasonal variation in resource availability and animals have evolved to cope with the associated caloric restriction. During winter in the NW Mediterranean Sea, the European sardine Sardina pilchardus naturally experiences caloric restriction due to a decrease in diversity and quantity of plankton. Ongoing global warming has, however, had deleterious effects on plankton communities such that food shortages may occur throughout the year, especially under warm conditions in the summer. We investigated the interactive effects of temperature and food availability on sardine metabolism, by continuously monitoring whole-animal respiration of groups of control (fed) and food-deprived sardines over a 60-day experiment in winter (12°C) or summer (20°C) conditions under natural photoperiod. In addition, we measured mitochondrial respiration of red muscle fibres, biometric variables and energy reserves, of individuals sampled at 30 and 60 days. This revealed that winter food deprivation elicits energy saving mechanisms at whole animal and cellular levels by maintaining a low metabolism to preserve energy reserves, allowing high survival. By contrast, despite energy saving mechanisms at the mitochondrial level, whole animal metabolic rate was high during food deprivation in summer, causing increased consumption of energy reserves at the muscular level and high mortality after 60 days. Furthermore, a 5-day refeeding did not improve survival and mortalities actually continued, suggesting that long-term food deprivation at high temperatures caused profound stress in sardines that potentially impaired nutrient absorption. potentially impaired nutrient absorption.)
Gnaiger 1987 Hydrobiol + (Aquatic oligochaetes are well known for th … Aquatic oligochaetes are well known for their ability to resist prolonged periods of anoxia. In fact, the observed mortality is more likely to result from laboratory stress (unnatural sediment, starvation, accumu1ation of toxic substances) than from lack of oxygen per se. ''Lumbriculus variegatus'' feeds under anoxia at 6 °C at a low rate and survives more than 40 days. A sudden transfer into anoxic water, however, results in a cessation of defaecation before the gut is half emptied, whereas the gut is completely emptied under aerobic conditions within 8-10 hours (11 °C).1Anoxic heat dissipation as measured by direct calorimetry2,3 is reduced by up to 80% relative to aerobic rates. The basal rate of oxygen uptake is independent of PO2 , above 3 kPa (15% air saturation), but the active rate shows a high degree of oxygen conformity. Whereas the theoretical oxycaloric equivalent yields an accurate estimation of aerobic heat dissipation in ''Lumbriculus'', anoxic catabolism of glycogen explains only up to 60% of the directly measured rates of anoxic heat dissipation in ''Lumbriculus'' and ''Tubifex''. Since unknown bioenergetic processes may be important under anoxia, direct calorimetry is required to assess total rates of energy expenditure in anoxic oligochaetes.s required to assess total rates of energy expenditure in anoxic oligochaetes.)
Kajma MiP2010 + (Arachidonic acid (AA) is a [[polyunsaturated fatty acid]] … Arachidonic acid (AA) is a [[polyunsaturated fatty acid]] (PUFA) which is highly concentrated in the membranes of the neuronal cells. Pathological conditions in the brain, such as ischemia increase the levels of AA in the cytoplasm [1]. Several lines of evidence indicate that the potent neuroprotective effect of PUFA may be linked with potassium channels. Moreover recent evidence suggests that potassium transport via channels presented in the inner mitochondrial membrane can trigger neuroprotection [2].In our study a single channel activity was measured with the use of patch-clamp of the mitoplasts isolated from embryonic hippocampal neurons. Mitoplasts were prepared from the sample of the mitochondria by addition to a hypotonic solution to induce swelling following outer membrane rapture. Our data provide evidence for the presence of large-conductance calcium activated potassium channels (mtBKCa) in the inner mitochondrial membrane of rat hippocampus. The channel conductance calculated based on current-voltage relations was equal to 288 pS. The activity of the channel deceased at low calcium concentration. Additionally, the channel activity was blocked by paxilline (inhibitor of the BKCa types channels). Moreover we demonstrated that the probability of opening of this channel is increased after the application of arachidonic acid. We also identified a novel channel which has current-voltage characteristics similar to the rectifying potassium channels. The channel conductance was equal to 60 pS. Patch-clamp studies showed that this channel is not sensitive to the known activators and inhibitors of mitochondrial potassium channels, but is regulated by arachidonic acid.In summary, the findings presented in this study provide new functional data suggesting the presence of the two channels in the rat hippocampus mitochondria: BKCa–type and rectifying potassium channel, both regulated by arachidonic acid.Grant sponsor: Ministry of Science and Higher Education P-N/031/20061. Adibhatla RM, Hatcher J F (2006) Phospholipase A2, reactive oxygen species, and lipid peroxidation in cerebral ischemia. Free Radical Biol. Med. 40: 376-387.2. Szewczyk A, Jarmuszkiewicz W, Kunz WS (2009) Mitochondrial potassium channels. IUBMB Life 61: 134-143.otassium channels. IUBMB Life 61: 134-143.)
Bauer 2013 Forensic Sci Int Genet (B) + (Archaeological excavations conducted at an … Archaeological excavations conducted at an early mediaeval cemetery in Volders (Tyrol, Austria) produced 141 complete skeletal remains dated between the 5th/6th and 12th/13th centuries. These skeletons represent one of the largest historical series of human remains ever discovered in the East Alpine region. Little historical information is available for this region and time period. The good state of preservation of these bioarchaeological finds offered the opportunity of performing molecular genetic investigations. Adequate DNA extraction methods were tested in the attempt to obtain as high DNA yields as possible for further analyses. Molecular genetic sex-typing using a dedicated PCR multiplex ("Genderplex") gave interpretable results in 88 remains, 78 of which had previously been sexed based on morphological features. We observed a discrepancy in sex determination between the two methods in 21 cases. An unbiased follow-up morphological examination of these finds showed congruence with the DNA results in all but five samples.h the DNA results in all but five samples.)
Brecht 2016 Toxicol In Vitro + (Arctigenin has previously been identified … Arctigenin has previously been identified as a potential anti-tumor treatment for advanced pancreatic cancer. However, the mechanism of how arctigenin kills cancer cells is not fully understood. In the present work we studied the mechanism of toxicity by arctigenin in the human pancreatic cell line, Panc-1, with special emphasis on the mitochondria. A comparison of Panc-1 cells cultured in glucose versus galactose medium was applied, allowing assessments of effects in glycolytic versus oxidative phosphorylation (OXPHOS)-dependent Panc-1 cells. For control purposes, the mitochondrial toxic response to treatment with arctigenin was compared to the anti-cancer drug, sorafenib, which is a tyrosine kinase inhibitor known for mitochondrial toxic off-target effects (Will et al., 2008). In both Panc-1 OXPHOS-dependent and glycolytic cells, arctigenin dissipated the mitochondrial membrane potential, which was demonstrated to be due to inhibition of the mitochondrial complexes II and IV. However, arctigenin selectively killed only the OXPHOS-dependent Panc-1 cells. This selective killing of OXPHOS-dependent Panc-1 cells was accompanied by generation of ER stress, mitochondrial membrane permeabilization and caspase activation leading to apoptosis and aponecrosis.Copyright © 2016 Elsevier Ltd. All rights reserved. © 2016 Elsevier Ltd. All rights reserved.)
Burtscher 2012 High Alt Med Biol + (Arnold Durig (1872-1961) grew up in the Au … Arnold Durig (1872-1961) grew up in the Austrian mountains in the period when intense exploration of the Alps started. As an enthusiastic mountaineer, scientist, and physician, he became one of the pioneers exploring physiological and pathophysiological aspects of humans sojourning to high altitudes. At the beginning of the 20th century, Durig was one of the great physiologists whose knowledge covered the whole field of physiology. Durig founded a renowned School and his students spread all over the world. He stayed in close contact with many colleagues and famous scientists, such as Albert Einstein and Sigmund Freud. Although he was an extremely productive and acknowledged physiologist and teacher at that time, his work and life are not very well known at the beginning of the 3rd millennium, even by high altitude physiologists. Thus, this article provides an overview on Durig's life and work, highlighting the most important scientific studies he performed at moderate and high altitudes, in an attempt to provide a few links to the development of high altitude research in the late 19th and early 20th centuries, complemented by some comments from a current Point of view.p>th centuries, complemented by some comments from a current Point of view.)
Zhang 2015 Stem Cells + (Arsenic is a global health hazard that imp … Arsenic is a global health hazard that impacts over 140 million individuals worldwide. Epidemiological studies reveal prominent muscle dysfunction and mobility declines following arsenic exposure; yet, mechanisms underlying such declines are unknown. The objective of this study was to test the novel hypothesis that arsenic drives a maladaptive fibroblast phenotype to promote pathogenic myomatrix remodeling and compromise the muscle stem (satellite) cell (MuSC) niche. Mice were exposed to environmentally-relevant levels of arsenic in drinking water before receiving a local muscle injury. Arsenic-exposed muscles displayed pathogenic matrix remodeling, defective myofiber regeneration and impaired functional recovery, relative to controls. When naïve human MuSCs were seeded onto 3D decellularized muscle constructs derived from arsenic-exposed muscles, cells displayed an increased fibrogenic conversion and decreased myogenicity, compared to cells seeded onto control constructs. Consistent with myomatrix alterations, fibroblasts isolated from arsenic-exposed muscle displayed sustained expression of matrix remodeling genes, the majority of which were mediated by NF-κB. Inhibition of NF-κB during arsenic exposure preserved normal myofiber structure and functional recovery after injury, suggesting that NF-κB signaling serves as an important mechanism of action for the deleterious effects of arsenic on tissue healing. Taken together, the results from this study implicate myomatrix biophysical and/or biochemical characteristics as culprits in arsenic-induced MuSC dysfunction and impaired muscle regeneration. It is anticipated that these findings may aid in the development of strategies to prevent or revert the effects of arsenic on tissue healing and, more broadly, provide insight into the influence of the native myomatrix on stem cell behavior.he native myomatrix on stem cell behavior.)
Chen 2019 Ecotoxicol Environ Saf + (Arsenic is a toxic metalloid that can caus … Arsenic is a toxic metalloid that can cause male reproductive malfunctions and is widely distributed in the environment. The aim of this study was to investigate the cytotoxicity of arsenic trioxide (ATO) induced GC-1 spermatogonial (spg) cells. Our results found that ATO increased the levels of catalase (CAT) and malonaldehyde (MDA) and reactive oxygen species (ROS), while decreasing glutathione (GSH) and the total antioxidant capacity (T-AOC). Therefore, ATO triggered oxidative stress in GC-1 spg cells. In addition, ATO also caused severe mitochondrial dysfunction that included an increase in residual oxygen consumption (ROX), and decreased the routine respiration, maximal and ATP-linked respiration (ATP-L-R), as well as spare respiratory capacity (SRC), and respiratory control rate (RCR); ATO also damaged the mitochondrial structure, including mitochondrial cristae disordered and dissolved, mitochondrial vacuolar degeneration. Moreover, degradation of p62, LC3 conversion, increasing the number of acidic vesicle organelles (AVOs) and autophagosomes and autolysosomes are demonstrated that the cytotoxicity of ATO may be associated with autophagy. Meanwhile, the metabolomics analysis results showed that 20 metabolites (10 increased and 10 decreased) were significantly altered with the ATO exposure, suggesting that maybe there are the perturbations in amino acid metabolism, lipid metabolism, glycan biosynthesis and metabolism, metabolism of cofactors and vitamins. We concluded that ATO was toxic to GC-1 spg cells via inducing oxidative stress, mitochondrial dysfunction and autophagy as well as the disruption of normal metabolism. This study will aid our understanding of the mechanisms behind ATO-induced spermatogenic toxicity.Copyright © 2019 Elsevier Inc. All rights reserved. 2019 Elsevier Inc. All rights reserved.)
Tweedie 2011 Am J Physiol Regul Integr Comp Physiol + (Artificial selection in rat has yielded hi … Artificial selection in rat has yielded high-capacity runners (HCR) and low-capacity runners (LCR) that differ in intrinsic (untrained) aerobic exercise ability and metabolic disease risk. To gain insight into how oxygen metabolism may have been affected by selection, we compared mitochondrial function, oxidative DNA damage (8-dihydroxy-guanosine; 8dOHG), and antioxidant enzyme activities in soleus muscle (Sol) and gastrocnemius muscle (Gas) of adult and aged LCR vs. HCR rats. In Sol of adult HCR rats, maximal ADP-stimulated respiration was 37% greater, whereas in Gas of adult HCR rats, there was a 23% greater complex IV-driven respiratory capacity and 54% greater leak as a fraction of electron transport capacity (suggesting looser mitochondrial coupling) vs. LCR rats. H2O2 emission per gram of muscle was 24-26% greater for both muscles in adult HCR rats vs. LCR, although H2O2 emission in Gas was 17% lower in HCR, after normalizing for citrate synthase activity (marker of mitochondrial content). Despite greater H2O2 emission, 8dOHG levels were 62-78% lower in HCR rats due to 62-96% higher superoxide dismutase activity in both muscles and 47% higher catalase activity in Sol muscle in adult HCR rats, with no evidence for higher 8 oxoguanine glycosylase (OGG1; DNA repair enzyme) protein expression. We conclude that genetic segregation for high running capacity has generated a molecular network of cellular adaptations, facilitating a superior response to oxidative stress.y has generated a molecular network of cellular adaptations, facilitating a superior response to oxidative stress.)
Moll 2016 bioRxiv + (As a consequence of the ongoing demographi … As a consequence of the ongoing demographic change, osteoporosis is considered as one of the mayor challenges for the health care system of the 21st century. However, the exact etiology of osteoporosis is far from being understood. Some evidence suggests that changes in stem cell metabolism might contribute to development of the disease. Therefore we evaluated whether differences of the morphology and/or the energy metabolism of mitochondria can be observed between human bone marrow derived mesenchymal stem cells obtained from osteoporotic patients as compared to non-osteoporotic controls. Mesenchymal stem cells were isolated from the bone marrow of senile osteoporotic and non osteoporotic patients, osteoporosis being assessed by dual energy X-ray absorptiometry. We then confirmed the stemness of the cells by FACS analysis of the expression of surface markers and by conducting multi-lineage differentiation experiments. And we finally investigated mitochondrial morphology and function with electron microscopy of cryo-fixed samples and by high-resolution respirometry, respectively. In addition we compared the energy metabolism of the stem cells to those of the osteosarcoma cell line MG-63. The data show, for the first time, the applicability on stem cells of the methods used here. Furthermore, our results indicated that there are no obvious differences detectable in mitochondrial morphology between cells from osteoporotic and non osteoporotic donors and that these cells also seem to be energetically indistinguishable with unchanged rates of ROUTINE respiration and respiratory capacity as well as unaltered oxygen consumption rates linked to different respiratory complexes. In summary, we could not detect any evidence indicating major changes of mitochondrial features in cells from osteoporotic patients.tures in cells from osteoporotic patients.)
Lemieux 2013 Abstract MiP2013 + (As a consequence of the rising overall obe … As a consequence of the rising overall obesity and aging of the population, insulin resistance (IR) and type 2 diabetes mellitus (T2DM) are becoming more prevalent in developing countries. Although evidence has been accumulating that T2DM is accompanied by mitochondrial dysfunction in muscles, the link between the mitochondrial dysfunction and the pathogenesis of T2DM remains unclear [1]. T2DM is a complex disease that causes various changes in the body metabolism. The difficulty is to identify mitochondrial defects involved in the cause of the disease rather than those that occur as consequences of the disease. Our study aims at understanding the role of mitochondrial metabolism in the muscle during the early stages of T2DM. The fructose-fed rat was used as the animal model of pre-diabetes. After only 6 weeks of a fructose-enriched diet (10% fructose added to the drinking water), rats showed clear signs of IR (glucose tolerance test). Mitochondrial respiration was measured in permeabilized muscle fibers using high-resolution respirometry (Oroboros Instruments, Austria) in the cardiac muscle and in two skeletal muscles, one oxidative (soleus) and one glycolytic (extensor digitorum longus, EDL). A wide range of substrates were used in order to cover the carbohydrate metabolism and the fatty acid oxidation. Acylcarnitine profiles were also measured in each tissue. The mitochondrial content was preserved in skeletal muscle as shown by the lack of difference of citrate synthase (CS) activity and Complex IV respiration. In the heart, CS activity was slightly, but significantly, reduced in the fructose-fed rats. The soleus muscle shows a decrease in Complex II respiration (succinate+rotenone) whereas the EDL muscle shows reduced Complex I and CI+II respiration in the presence of pyruvate but not when glutamate is used as a substrate. There is no defect in fatty acid oxidation with the soleus muscle in fructose-fed animals. The EDL muscle, however, shows a defect located in the long-chain acyl-CoA dehydrogenase (LCAD). Surprisingly, the mitochondrial dysfunction in the heart mirrors the mitochondrial dysfunction in the EDL muscle, rather than in the soleus.Our results highlight important early mitochondrial dysfunction associated with T2DM. The defects are clearly specific to the type of muscle studied. Furthermore, our study also points to the importance of differences between human and animal models because the role of LCAD in fatty acid oxidation is significant in rodent muscles but not in most human tissues [2].muscles but not in most human tissues [2].)
Floyd 2022 Lancet + (As a group of clinicians, we voice our con … As a group of clinicians, we voice our concerns about recent changes to publication fees. Having coauthored an original article together, we were faced with the dilemma of having to pay £2000 in publication fees. This contrasts with a situation only 2 years ago when publication in most journals was free of charge or only incurred a small administration fee. The situation was further compounded by the fact that these costs are similar across the major journals in our specialty (appendix). Our institution has no dedicated funds to cover publication fees, and we were faced with either having to pay ourselves or retracting the manuscript. It was later agreed that our department would cover the costs on a compassionate basis. cover the costs on a compassionate basis.)
Kaiser 2017 Science + (As a growing number of biologists formally … As a growing number of biologists formally share their papers in online repositories before any peer review or journal publication, it’s often said that they are catching up with physicists, who have posted preprints in the online arXiv server since 1991. But biomedical scientists actually made a start earlier, reveals a researcher who has traced the "forgotten experiment" in which the National Institutes of Health (NIH) created a preprint exchange in the 1960s that publishers ultimately forced to close.hat publishers ultimately forced to close.)
Wu 2022 Neuromolecular Med + (As a multi-functional cellular organelle, … As a multi-functional cellular organelle, mitochondrial metabolic reprogramming is well recognized as a hallmark of cancer. The center of mitochondrial metabolism is oxidative phosphorylation (OXPHOS), in which cells use enzymes to oxidize nutrients, thereby converting the chemical energy to the biological energy currency ATPs. OXPHOS also creates the mitochondrial membrane potential and serve as the driving force of other mitochondrial metabolic pathways and experiences significant reshape in the different stages of tumor progression. In this minireview, we reviewed the major mitochondrial pathways that are connected to OXPHOS and are affected in cancer cells. In addition, we summarized the function of novel bio-active molecules targeting mitochondrial metabolic processes such as OXPHOS, mitochondrial membrane potential and mitochondrial dynamics. These molecules exhibit intriguing preclinical and clinical results and have been proven to be promising antitumor candidates in recent studies.ng antitumor candidates in recent studies.)
Luo 2020 Int J Mol Sci + (As an essential organelle in nucleated euk … As an essential organelle in nucleated eukaryotic cells, mitochondria play a central role in energy metabolism, maintenance of redox balance, and regulation of apoptosis. Mitochondrial dysfunction, either due to the TCA cycle enzyme defects, mitochondrial DNA genetic mutations, defective mitochondrial electron transport chain, oxidative stress, or aberrant oncogene and tumor suppressor signaling, has been observed in a wide spectrum of human cancers. In this review, we summarize mitochondrial dysfunction induced by these alterations that promote human cancers.se alterations that promote human cancers.)
Mosegaard 2020 Int J Mol Sci + (As an essential vitamin, the role of ribof … As an essential vitamin, the role of riboflavin in human diet and health is increasingly being highlighted. Insufficient dietary intake of riboflavin is often reported in nutritional surveys and population studies, even in non-developing countries with abundant sources of riboflavin-rich dietary products. A latent subclinical riboflavin deficiency can result in a significant clinical phenotype when combined with inborn genetic disturbances or environmental and physiological factors like infections, exercise, diet, aging and pregnancy. Riboflavin, and more importantly its derivatives, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), play a crucial role in essential cellular processes including mitochondrial energy metabolism, stress responses, vitamin and cofactor biogenesis, where they function as cofactors to ensure the catalytic activity and folding/stability of flavoenzymes. Numerous inborn errors of flavin metabolism and flavoenzyme function have been described, and supplementation with riboflavin has in many cases been shown to be lifesaving or to mitigate symptoms. This review discusses the environmental, physiological and genetic factors that affect cellular riboflavin status. We describe the crucial role of riboflavin for general human health, and the clear benefits of riboflavin treatment in patients with inborn errors of metabolism.patients with inborn errors of metabolism.)
Hickey 2014 Abstract MiP2014 + (As approximately 80% of diabetics die from … As approximately 80% of diabetics die from heart failure, understanding diabetic cardiomyopathy is crucial. Mitochondria occupy 35-40% of the mammalian cardiomyocyte volume, supply 95% of the hearts’ ATP, and diabetic heart mitochondria show impaired structure, arrangement and function. We predict that bioenergetic inefficiencies are present in diabetic heart mitochondria; therefore, we explored mitochondrial proton and electron handling by linking oxygen flux within streptozotocin (STZ)-induced-diabetic Sprague-Dawley rat heart tissues, to steady-state ATP synthesis, reactive oxygen species (ROS) production and mitochondrial membrane potential (Δ''Ψ''). By coupling high-resolution respirometers with purpose-built fluorometers, we followed Magnesium Green (ATP synthesis), Amplex Ultra Red (ROS production) and safranin-O (Δ''Ψ''). Relative to control rats, the tissue-mass specific respiration of STZ-diabetic hearts was depressed in oxidative phosphorylating (OXPHOS) states. Steady-state ATP synthesis capacity was almost a third lower in STZ-diabetic heart and relative to O2 flux, this equates to an estimated 12% depression in OXPHOS efficiency. However, with anoxic transition, STZ-diabetic and control heart tissues showed similar ATP hydrolysis capacities through reversal of the F1/F0 ATP synthase. STZ-diabetic cardiac mitochondria also produced more net ROS, relative to oxygen flux (ROS/O) in the OXPHOS state. While Δ''Ψ'' did not differ between groups, the time to develop Δ''Ψ'' with the onset of OXPHOS was protracted in STZ-diabetic mitochondria. ROS/O is higher in life-like OXPHOS states, and potential delays in the time to develop Δ''Ψ'' may delay ATP synthesis with inter-beat fluctuations in ADP concentrations. Whereas diabetic cardiac mitochondria produce less ATP in normoxia, they consume as much ATP in anoxic infarct-like states (Fig. 1). in normoxia, they consume as much ATP in anoxic infarct-like states (Fig. 1).)
Pham 2014 Am J Physiol + (As approximately 80% of diabetics die from … As approximately 80% of diabetics die from heart failure, understanding diabetic cardiomyopathy is crucial. Mitochondria occupy 35-40% of mammalian cardiomyocyte volume, supply 95% of the hearts' ATP, and diabetic heart mitochondria show impaired structure, arrangement and function. We predict that bioenergetic efficiencies are present in diabetic heart mitochondria; therefore we explored mitochondrial proton and electron handling by linking oxygen flux within streptozotocin (STZ)-induced-diabetic Sprague-Dawley rat heart tissues, to steady-state ATP synthesis, Reactive Oxygen Species (ROS) production, and mitochondrial membrane potential (Δ''Ψ''). By coupling high-resolution respirometers with purpose-built fluorometers, we followed Magnesium Green (ATP synthesis), Amplex Ultra Red (ROS production), and safranin-O (Δ''Ψ''). Relative to control rats, the mass-specific respiration of STZ-diabetic hearts was depressed in oxidative phosphorylating (OXPHOS) states. Steady-state ATP synthesis capacity was almost a third lower in STZ-diabetic heart and relative to O2 flux, this equates to an estimated 12% depression in OXPHOS efficiency. However, with anoxic transition, STZ-diabetic and control heart tissues showed similar ATP hydrolysis capacities through reversal of the F1/F0 ATP-synthase. STZ-diabetic cardiac mitochondria also produced more net ROS relative to oxygen flux (ROS/O) in OXP. While Δ''Ψ'' did not differ between groups, the time to develop Δ''Ψ'' with the onset of OXPHOS was protracted in STZ-diabetic mitochondria. ROS/O is higher in life-like OXPHOS states and potential delays in the time to develop Δ''Ψ'' may delay ATP synthesis with inter-beat fluctuations in ADP concentrations. Whereas diabetic cardiac mitochondria produce less ATP in normoxia, they consume as much ATP in anoxic infarct-like states.as much ATP in anoxic infarct-like states.)
Grewal 2020 Exp Neurol + (As components of the Mediterranean diet (M … As components of the Mediterranean diet (MedDiet) olive polyphenols may play a crucial role for the prevention of Alzheimer's disease (AD). Since mitochondrial dysfunction is involved in both, brain ageing and early AD, effects of 10 different purified phenolic secoiridoids (hydroxytyrosol, tyrosol, oleacein, oleuroside, oleuroside aglycon, oleuropein, oleocanthal, ligstroside, ligstroside aglycone and ligustaloside B) and two metabolites (the plant metabolite elenolic acid and the mammalian metabolite homovanillic acid) were tested in very low doses on mitochondrial function in SH-SY5Y-APP695 cells - a cellular model of early AD. All tested secoiridoids significantly increased basal ATP levels in SY5Y-APP695 cells. Oleacein, oleuroside, oleocanthal and ligstroside showed the highest effect on ATP levels and were additionally tested on mitochondrial respiration. Only oleocanthal and ligstroside were able to enhance the capacity of respiratory chain complexes. To investigate their underlying molecular mechanism, the expression of genes associated with mitochondrial biogenesis, respiration and antioxidative capacity (PGC1-α, SIRT1, CREB1, NRF1, TFAM, complex I, IV and V, GPx1, SOD2, CAT) were determined using RT-PCR. Exclusively ligstroside increased mRNA expression of SIRT1, CREB1, complex I, and GPx1. Furthermore, oleocanthal but not ligstroside decreased Aβ 1-40 levels in SH-SY5Y-APP695 cells. To investigate the ''in vivo'' effects of purified secoiridoids, the two most promising compounds (oleocanthal and ligstroside) were tested in a mouse model of ageing. Female NMRI mice, aged 12 months, received a diet supplemented with 50 mg/kg diet oleocanthal or ligstroside for 6 months (equivalent to 6.25 mg/kg b.w.). Young (3 months) and aged (18 months) mice served as controls. Ligstroside fed mice showed improved spatial working memory. Furthermore, ligstroside restored brain ATP levels in aged mice and led to a significant life extension compared to aged control animals. Our findings indicate that purified ligstroside has outstanding performance on mitochondrial bioenergetics in models of early AD and brain ageing by mechanisms that may not interfere with Aβ production. Additionally, ligstroside expanded the lifespan in aged mice and enhanced cognitive function.Copyright © 2019. Published by Elsevier Inc.gnitive function. Copyright © 2019. Published by Elsevier Inc.)
Ponsot 2005 J Cell Physiol + (As energetic metabolism is crucial for mus … As energetic metabolism is crucial for muscles, they develop different adaptations to respond to fluctuating demand among muscle types. Whereas quantitative characteristics are known, no study described simultaneously quantitative and qualitative differences among muscle types in terms of substrates utilization patterns. This study thus defined the pattern of substrates preferential utilization by mitochondria from glycolytic gastrocnemius (GAS) and oxidative soleus (SOL) skeletal muscles and from heart left ventrical (LV) in rats. We measured in situ, ADP (2 mM)-stimulated, mitochondrial respiration rates from skinned fibers in presence of increasing concentrations of pyruvate (Pyr) + malate (Mal), palmitoyl-carnitine (Palm-C) + Mal, glutamate (Glut) + Mal, glycerol-3-phosphate (G3-P), lactate (Lact) + Mal. Because the fibers oxygen uptake (Vs) followed Michaelis-Menten kinetics in function of substrates level we determined the Vs and Km, representing maximal oxidative capacity and the mitochondrial sensibility for each substrate, respectively. Vs were in the order GAS < SOL < LV for Pyr, Glu, and Palm-C substrates, whereas in the order SOL = LV < GAS with G3-P. Moreover, the relative capacity to oxidize Palm-C is extremely higher in LV than in SOL. Vs was not stimulated by the Lact substrate. The Km was equal for Pyr among muscles, but much lower for G3-P in GAS and lower for Palm-C in LV. These results demonstrate qualitative mitochondrial tissue specificity for metabolic pathways. Mitochondria of glycolytic muscle fibers are well adapted to play a central role for maintaining a satisfactory cytosolic redox state in these fibers, whereas mitochondria of LV developed important capacities to use fatty acids. developed important capacities to use fatty acids.)
Salin 2015 Abstract MiP2015 + (As global temperatures rise, there is a gr … As global temperatures rise, there is a growing need to understand the proximate causes that determine the boundary of an organism’s thermal niche. Individuals can vary in how they respond to temperature increases, but the mechanisms responsible for this inter-individual variation are unclear.Here we tested the hypothesis that individual performance at high temperatures depends on mitochondrial respiratory properties. We assessed the food intake in an ''ad libitum'' diet, rate of growth in mass and length, and mitochondrial function in liver and white muscle of juvenile brown trout ''Salmo trutta'' gradually acclimated to the high testing temperature (19°C).Food intake and growth rate were highly variable amongst fish: food intake varied by 10 among individuals, some fish did not grow, some lost body weight whilst others grew and increased body mass. Around 50% of the individual variation in food intake was explained by liver and muscle mitochondrial function. Individuals with the highest LEAK respiration in liver and muscle exhibited the lowest food intake. Moreover, food intake was worst in individuals with a lower muscle phosphorylating respiration, and in turn a lower respiratory control ratio (RCR). After accounting for food intake, no aspect of mitochondrial function could explain individual variation in growth.Our results demonstrate that individuals with higher LEAK respiration and lower coupling in mitochondria (as estimated by the RCR) had the poorest performance, suggesting that their capacity for ATP production at 19°C could not support an adequate foraging. Our findings suggest that differences in the ability of mitochondria to generate ATP could shape the boundary of an individual’sthermal niche.boundary of an individual’s thermal niche.)
Fangue 2009 J Exp Biol + (As global temperatures rise, there is a gr … As global temperatures rise, there is a growing need to understand the physiological mechanisms that determine an organism's thermal niche. Here, we test the hypothesis that increases in mitochondrial capacity with cold acclimation and adaptation are associated with decreases in thermal tolerance using two subspecies of killifish (''Fundulus heteroclitus'') that differ in thermal niche. We assessed whole-organism metabolic rate, mitochondrial amount and mitochondrial function in killifish acclimated to several temperatures. Mitochondrial enzyme activities and mRNA levels were greater in fish from the northern subspecies, particularly in cold-acclimated fish, suggesting that the putatively cold-adapted northern subspecies has a greater capacity for increases in mitochondrial amount in response to cold acclimation. When tested at the fish's acclimation temperature, maximum ADP-stimulated (State III) rates of mitochondrial oxygen consumption ''in vitro'' were greater in cold-acclimated northern fish than in southern fish but did not differ between subspecies at higher acclimation temperatures. Whole-organism metabolic rate was greater in fish of the northern subspecies at all acclimation temperatures. Cold acclimation also changed the response of mitochondrial respiration to acute temperature challenge. Mitochondrial oxygen consumption was greater in cold-acclimated northern fish than in southern fish at low test temperatures, but the opposite was true at high test temperatures. These differences were reflected in whole-organism oxygen consumption. Our data indicate that the plasticity of mitochondrial function and amount differs between killifish subspecies, with the less high-temperature tolerant, and putatively cold adapted, northern subspecies having greater ability to increase mitochondrial capacity in the cold. However, there were few differences in mitochondrial properties between subspecies at warm acclimation temperatures, despite differences in both whole-organism oxygen consumption and thermal tolerance at these temperatures.d thermal tolerance at these temperatures.)
Cooper 2000 Sunderland (MA): Sinauer Associates + (As in the first edition, The Cell is focus … As in the first edition, The Cell is focused on the molecular biology of cells as a unifying theme, with specialized topics discussed throughout the book as examples of more general principles. Aspects of developmental biology, the immune system, the nervous system, and plant biology are thus discussed in their broader biological context in chapters covering areas such as genome structure, gene expression, DNA rearrangements, the plasma membrane, cell signaling, and the cell cycle. Relationships between cell biology and medicine are similarly discussed throughout the text, as well as being highlighted in the Molecular Medicine essays that are included as a special feature in each chapter. These discussions illustrate the striking impact of molecular and cellular biology on human health, and are intended to stimulate as well as inform those students interested in medicine.orm those students interested in medicine.)
Bullon 2016 Periodontol 2000 + (As many diseases have been shown to have s … As many diseases have been shown to have several or indirect causes (i.e. are multifactorial) the question is what is the relative importance of each factor in a given disease? Also, what happens when some diseases, although apparently disparate, share causative factors and/or tissue pathologies? Host inflammation response mechanisms are largely shared by the body's different tissues and systems and only recently has special attention been paid to the possible linkages among chronic periodontitis and other chronic systemic diseases. The aim of this review was to consider and discuss the mounting evidence that the basis for the inter-relationships between chronic periodontitis and atheromatous disease and diabetes lie at a fundamental intracellular level, namely oxidative stress and mitochondrial dysfunction, as a meeting background among such chronic diseases and periodontitis.© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. Sons A/S. Published by John Wiley & Sons Ltd.)
Huerta-Sanchez 2014 Nature + (As modern humans migrated out of Africa, t … As modern humans migrated out of Africa, they encountered many new environmental conditions, including greater temperature extremes, different pathogens and higher altitudes. These diverse environments are likely to have acted as agents of natural selection and to have led to local adaptations. One of the most celebrated examples in humans is the adaptation of Tibetans to the hypoxic environment of the high-altitude Tibetan plateau1, 2, 3. A hypoxia pathway gene, EPAS1, was previously identified as having the most extreme signature of positive selection in Tibetans4, 5, 6, 7, 8, 9, 10, and was shown to be associated with differences in haemoglobin concentration at high altitude. Re-sequencing the region around EPAS1 in 40 Tibetan and 40 Han individuals, we find that this gene has a highly unusual haplotype structure that can only be convincingly explained by introgression of DNA from Denisovan or Denisovan-related individuals into humans. Scanning a larger set of worldwide populations, we find that the selected haplotype is only found in Denisovans and in Tibetans, and at very low frequency among Han Chinese. Furthermore, the length of the haplotype, and the fact that it is not found in any other populations, makes it unlikely that the haplotype sharing between Tibetans and Denisovans was caused by incomplete ancestral lineage sorting rather than introgression. Our findings illustrate that admixture with other hominin species has provided genetic variation that helped humans to adapt to new environments.elped humans to adapt to new environments.)
Zhao 2019 Pharmacol Res + (As one classic anticancer drug, clinical a … As one classic anticancer drug, clinical application of Doxorubicin (Dox) is limited due to its side effects. In our previous work, we have investigated the drug targets to treat Dox-induced cardiotoxicity, hepatotoxicity and nephrotoxicity. In this paper, the mechanisms and new drug-target associated with Dox-induced hepatotoxicity were explored. The results showed that Dox markedly inhibited cell viability and cellular respiration, induced cell morphologic change and increased ROS level. Moreover, Dox increased ALT and AST levels, caused pathological damage, increased MDA level and decreased SOD level in mice. Mechanism investigation showed that Dox markedly up-regulated the expression level of miR-128-3p, down-regulated Sirt1 expression level and affected the protein levels of Nrf2, Keap1, Sirt3, NQO1 and HO-1 to cause oxidative stress in liver. Furthermore, double-luciferase reporter assay, and co-transfection test showed that miR-128-3p directly targeted Sirt1. In addition, miR-128-3p mimics in AML-12 cells enhanced Dox-induced oxidative damage via inhibiting cellular respiration, increasing ROS level and mitochondrial superoxide formation. The protein levels of Sirt1, Nrf2, Sirt3, NQO1 and HO-1 in miR-128-3p mimic + Dox group were decreased compared with Dox group. Transfection of miR-128-3p inhibitor weakened Dox-induced oxidative damage via increasing cellular respiration, suppressing cellular ROS level and mitochondrial superoxide formation. The protein levels of Sirt1, Nrf2, Sirt3, NQO1 and HO-1 in miR-128-3p inhibitor + Dox group were increased compared with Dox group. In mice, Dox-induced liver damage was deteriorated by miR-128-3p agomir via increasing the levels of ALT, AST, MDA, and down-regulating the protein levels of Sirt1, Nrf2, Sirt3, NQO1 and HO-1. While, miR-128-3p antagomir alleviated liver injury via decreasing the levels of ALT, AST, MDA, and up-regulating the protein levels of Sirt1, Nrf2, Sirt3, NQO1 and HO-1. Our data showed that miRNA-128-3p aggravated Dox-induced liver injury by promoting oxidative stress via targeting Sirt1, which should be considered as one new drug target to treat Dox-induced liver injury.Copyright © 2019 Elsevier Ltd. All rights reserved. 2019 Elsevier Ltd. All rights reserved.)
Shirihai 2014 Abstract MiP2014 + (As our relationship with mitochondria evol … As our relationship with mitochondria evolves, we remain fascinated by the impact of this organelle in two seemingly unrelated conditions: aging and metabolic diseases. While aging involves insufficiency of mitochondrial quality control and turnover mechanisms (such as autophagy), type II diabetes and obesity are influenced by the ability of the organism to deal with excess nutrient environment. The observation that both conditions are impacted by the duration of exposure to excess nutrient environment raises the question: Are the tasks of handling nutrients in excess and maintaining quality control ever in conflict? Mitochondria go through continuous cycles of selective fusion and fission, referred to as the “mitochondrial life cycle”, to maintain the quality of their function [3-5]. Changes in mitochondrial architecture can represent an adaptation of mitochondria to respire according to the bioenergetic needs of the cell [2]. Conditions requiring high mitochondrial ATP synthesis capacity and/or efficiency, such as limited nutrient availability, are associated with mitochondrial elongation [1]; reviewed in [2], while conditions of excess energy supply and relatively low ATP demand, such as beta-cells exposed to excess nutrients, induce mitochondrial fragmentation [6]. This raises the possibility that mitochondrial fragmentation supports uncoupled respiration and thus increases energy expenditure by promoting nutrient oxidation towards heat production, rather than towards mitochondrial ATP synthesis. To test this hypothesis, we explored a system where a robust shift from coupled to uncoupled respiration and increased energy expenditure can occur. The brown adipocyte offers a unique system where transition to uncoupling can occur within minutes and in a physiological rather than pathological context. Therefore, it represents an attractive model for studying the regulation of energy expenditure induced by hormones. Our results indicate that norepinephrine induces changes to mitochondrial architecture that serve as an amplification pathway for uncoupling in brown adipocytes. Remarkably, we now have evidence that similar changes, though at a longer time scale, occur in the beta cells under excess nutrient environment. In the beta cell, nutrient–induced fragmentation is associated with increased uncoupling and the enhanced consumption of excess nutrients, thereby serving as an adaptive mechanism. Placement of bioenergetic adaptation and quality control as competing tasks of mitochondrial dynamics might provide a new mechanism, linking excess nutrient environment to progressive mitochondrial dysfunction, common to age-related diseases.sfunction, common to age-related diseases.)
Guan 1999 J Biotechnol + (As part of an overall aim to base the feed … As part of an overall aim to base the feeding of substrates to cultured animal cells on their actual metabolic needs,we have developed a stoichiometric approach centred on the macronutrients in the medium. Heat flux records theoverall metabolic activity and therefore was the sensitive indicator of changing metabolic requirement. Analyses weremade of the experimental measurements on two engineered cell lines in batch culture, the 2C11-12 macrophagehybridoma cell capable of the respiratory burst and the CHO320 constitutively producing human interferon-g. Thecrux was to construct simplified stoichiometric equations for the growth reactions to represent metabolic activity asit changed with time. Beforehand, it was essential to select the appropriate components for the equations. The choicewas then justified by constructing enthalpy balances in which the ratio of heat flux to enthalpy flux must be close tounity for validation. By combining the stoichiometric approach with heat flow measurements, it was shown boththeoretically and experimentally that the set of stoichiometric coefficients constituting a validated growth equation hasa one-to-one corresponding relationship to the metabolic activity of the average cell population. Thus, a strategy wasestablished for feeding the cells at any one time with the correct ratio of the major substrates, glucose and glutamine,in response to metabolic requirements that change with time.abolic requirements that change with time.)
DeBalsi 2017 Ageing Res Rev + (As regulators of bioenergetics in the cell … As regulators of bioenergetics in the cell and the primary source of endogenous reactive oxygen species (ROS), dysfunctional mitochondria have been implicated for decades in the process of aging and age-related diseases. Mitochondrial DNA (mtDNA) is replicated and repaired by nuclear-encoded mtDNA polymerase γ (Pol γ) and several other associated proteins, which compose the mtDNA replication machinery. Here, we review evidence that errors caused by this replication machinery and failure to repair these mtDNA errors results in mtDNA mutations. Clonal expansion of mtDNA mutations results in mitochondrial dysfunction, such as decreased electron transport chain (ETC) enzyme activity and impaired cellular respiration. We address the literature that mitochondrial dysfunction, in conjunction with altered mitochondrial dynamics, is a major driving force behind aging and age-related diseases. Additionally, interventions to improve mitochondrial function and attenuate the symptoms of aging are examined.enuate the symptoms of aging are examined.)
Dickinson 2013 Cell Death Differ + (As stem cells undergo differentiation, mit … As stem cells undergo differentiation, mitochondrial DNA (mtDNA) copy number is strictly regulated in order that specialized cells can generate appropriate levels of adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS) to undertake their specific functions. It is not understood whether tumor-initiating cells regulate their mtDNA in a similar manner or whether mtDNA is essential for tumorigenesis. We show that human neural stem cells (hNSCs) increased their mtDNA content during differentiation in a process that was mediated by a synergistic relationship between the nuclear and mitochondrial genomes and results in increased respiratory capacity. Differentiating multipotent glioblastoma cells failed to match the expansion in mtDNA copy number, patterns of gene expression and increased respiratory capacity observed in hNSCs. Partial depletion of glioblastoma cell mtDNA rescued mtDNA replication events and enhanced cell differentiation. However, prolonged depletion resulted in impaired mtDNA replication, reduced proliferation and induced the expression of early developmental and pro-survival markers including POU class 5 homeobox 1 (OCT4) and sonic hedgehog (SHH). The transfer of glioblastoma cells depleted to varying degrees of their mtDNA content into immunocompromised mice resulted in tumors requiring significantly longer to form compared with non-depleted cells. The number of tumors formed and the time to tumor formation was relative to the degree of mtDNA depletion. The tumors derived from mtDNA depleted glioblastoma cells recovered their mtDNA copy number as part of the tumor formation process. These outcomes demonstrate the importance of mtDNA to the initiation and maintenance of tumorigenesis in glioblastoma multiforme. tumorigenesis in glioblastoma multiforme.)
Rodgers 2021 Elife + (As the final outputs of the Reproducibility Project: Cancer Biology are published, it is clear that preclinical research in cancer biology is not as reproducible as it should be.)
Rai 2022 G3 (Bethesda) + (As the fruit fly, Drosophila melanogaster, … As the fruit fly, Drosophila melanogaster, progresses from one life stage to the next, many of the enzymes that compose intermediary metabolism undergo substantial changes in both expression and activity. These predictable shifts in metabolic flux allow the fly meet stage-specific requirements for energy production and biosynthesis. In this regard, the enzyme glycerol-3-phosphate dehydrogenase 1 (GPDH1) has been the focus of biochemical genetics studies for several decades and, as a result, is one of the most well-characterized Drosophila enzymes. Among the findings of these earlier studies is that GPDH1 acts throughout the fly lifecycle to promote mitochondrial energy production and triglyceride accumulation while also serving a key role in maintaining redox balance. Here, we expand upon the known roles of GPDH1 during fly development by examining how depletion of both the maternal and zygotic pools of this enzyme influences development, metabolism, and viability. Our findings not only confirm previous observations that Gpdh1 mutants exhibit defects in larval development, lifespan, and fat storage but also reveal that GPDH1 serves essential roles in oogenesis and embryogenesis. Moreover, metabolomics analysis reveals that a Gpdh1 mutant stock maintained in a homozygous state exhibits larval metabolic defects that significantly differ from those observed in the F1 mutant generation. Overall, our findings highlight unappreciated roles for GPDH1 in early development and uncover previously undescribed metabolic adaptations that could allow flies to survive the loss of this key enzyme.es to survive the loss of this key enzyme.)
MitoEAGLE Task Group States and rates + (As the knowledge base and importance of mi … As the knowledge base and importance of mitochondrial physiology to human health expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow guidelines of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols to the nomenclature of classical bioenergetics. We endeavour to provide a balanced view on mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of databases of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery.ucation, and ultimately further discovery.)
Radogna 2021 Methods Mol Biol + (As the powerhouse of the cell, mitochondri … As the powerhouse of the cell, mitochondria, plays a crucial role in many aspects of life, whereby mitochondrial dysfunctions are associated with pathogenesis of many diseases, like neurodegenerative diseases, obesity, cancer, and metabolic as well as cardiovascular disorders. Mitochondria analysis frequently starts with isolation and enrichment procedures, which have become increasingly important in biomedical research. Unfortunately, isolation procedures can easily cause changes in the structural integrity of mitochondria during in vitro handling having impact on their function. This carries the risk that conclusions about isolated mitochondria may be drawn on the basis of experimental artifacts. Here we critically review a commonly used isolation procedure for mitochondria utilizing differential (gradient) centrifugation and depict major challenges to achieve "functional" mitochondria as basis for comprehensive physiological studies.s for comprehensive physiological studies.)
Lehr 2021 Methods Mol Biol + (As the powerhouse of the cell, mitochondri … As the powerhouse of the cell, mitochondria, plays a crucial role in many aspects of life, whereby mitochondrial dysfunctions are associated with pathogenesis of many diseases, like neurodegenerative diseases, obesity, cancer, and metabolic as well as cardiovascular disorders. Mitochondria analysis frequently starts with isolation and enrichment procedures, which have become increasingly important in biomedical research. Unfortunately, isolation procedures can easily cause changes in the structural integrity of mitochondria during ''in vitro'' handling having impact on their function. This carries the risk that conclusions about isolated mitochondria may be drawn on the basis of experimental artifacts. Here we critically review a commonly used isolation procedure for mitochondria utilizing differential (gradient) centrifugation and depict major challenges to achieve "functional" mitochondria as basis for comprehensive physiological studies.s for comprehensive physiological studies.)
De Jager 2017 Adv Exp Med Biol + (As ultraviolet (UV) radiation is naturally … As ultraviolet (UV) radiation is naturally and ubiquitously emitted by the sun, almost everyone is exposed to it on a daily basis, and it is necessary for normal physiological function. Human exposure to solar UV radiation thus has important health implications. The generation of reactive oxygen species (ROS) by UV radiation is one of the mechanisms through which UV light can manifest its possible detrimental effects on health. When an imbalance develops due to ROS generation exceeding the body's antioxidant defence mechanisms, oxidative stress can develop. Oxidative stress can lead to cellular damage (e.g. lipid peroxidation and DNA fragmentation), apoptosis and cell death. Broadly UV can induce ROS by affecting the cellular components directly or by means of photosensitization mechanisms. More specifically UV light can induce ROS by affecting the enzyme catalase and up-regulating nitric oxide synthase (NOS) synthesis. It may also cause a decrease in protein kinase C (PKC) expression leading to increased ROS production. UVR is capable of modifying DNA and other chromophores resulting in elevated ROS levels. The effects of raised ROS levels can vary based on the intracellular oxidant status of the cell. It is therefore important to protect yourself against the potentially harmful effects of UV light as it can lead to pathological UV-induced ROS production.to pathological UV-induced ROS production.)