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• Seok 2013 Proc Natl Acad Sci U S A  + (A cornerstone of modern biomedical researc … A cornerstone of modern biomedical research is the use of mouse models to explore basic pathophysiological mechanisms, evaluate new therapeutic approaches, and make go or no-go decisions to carry new drug candidates forward into clinical trials. Systematic studies evaluating how well murine models mimic human inflammatory diseases are nonexistent. Here, we show that, although acute inflammatory stresses from different etiologies result in highly similar genomic responses in humans, the responses in corresponding mouse models correlate poorly with the human conditions and also, one another. Among genes changed significantly in humans, the murine orthologs are close to random in matching their human counterparts (e.g., R(2) between 0.0 and 0.1). In addition to improvements in the current animal model systems, our study supports higher priority for translational medical research to focus on the more complex human conditions rather than relying on mouse models to study human inflammatory diseases.dels to study human inflammatory diseases.)
• Logan 2018 Mol Metab  + (A decline in mitochondrial function and bi … A decline in mitochondrial function and biogenesis as well as increased reactive oxygen species (ROS) are important determinants of aging. With advancing age, there is a concomitant reduction in circulating levels of insulin-like growth factor-1 (IGF-1) that is closely associated with neuronal aging and neurodegeneration. In this study, we investigated the effect of the decline in IGF-1 signaling with age on astrocyte mitochondrial metabolism and astrocyte function and its association with learning and memory.</br></br>Learning and memory was assessed using the radial arm water maze in young and old mice as well as tamoxifen-inducible astrocyte-specific knockout of IGFR (GFAP-Cre^TAM/igfr^f/f). The impact of IGF-1 signaling on mitochondrial function was evaluated using primary astrocyte cultures from igfr^f/f mice using AAV-Cre mediated knockdown using Oroboros respirometry and Seahorse assays.</br></br>Our results indicate that a reduction in IGF-1 receptor (IGFR) expression with age is associated with decline in hippocampal-dependent learning and increased gliosis. Astrocyte-specific knockout of IGFR also induced impairments in working memory. Using primary astrocyte cultures, we show that reducing IGF-1 signaling via a 30-50% reduction IGFR expression, comparable to the physiological changes in IGF-1 that occur with age, significantly impaired ATP synthesis. IGFR deficient astrocytes also displayed altered mitochondrial structure and function and increased mitochondrial ROS production associated with the induction of an antioxidant response. However, IGFR deficient astrocytes were more sensitive to H₂O₂-induced cytotoxicity. Moreover, IGFR deficient astrocytes also showed significantly impaired glucose and Aβ uptake, both critical functions of astrocytes in the brain.</br></br>Regulation of astrocytic mitochondrial function and redox status by IGF-1 is essential to maintain astrocytic function and coordinate hippocampal-dependent spatial learning. Age-related astrocytic dysfunction caused by diminished IGF-1 signaling may contribute to the pathogenesis of Alzheimer's disease and other age-associated cognitive pathologies.</br></br>Copyright © 2018 The Authors. Published by Elsevier GmbH. All rights reserved.cognitive pathologies. Copyright © 2018 The Authors. Published by Elsevier GmbH. All rights reserved.)
• Elliehausen 2021 Exp Gerontol  + (A decline in skeletal muscle mitochondrial … A decline in skeletal muscle mitochondrial function is associated with the loss of skeletal muscle size and function during knee osteoarthritis (OA). We have recently reported that 12-weeks of dietary rapamycin (Rap, 14 ppm), with or without metformin (Met, 1000 ppm), increased plasma glucose and OA severity in male Dunkin Hartley (DH) guinea pigs, a model of naturally occurring, age-related OA. The purpose of the current study was to determine if increased OA severity after dietary Rap and Rap+Met was accompanied by impaired skeletal muscle mitochondrial function. Mitochondrial respiration and hydrogen peroxide (H₂O₂) emissions were evaluated in permeabilized muscle fibers via high-resolution respirometry and fluorometry using either a saturating bolus or titration of ADP. Rap and Rap+Met decreased complex I (CI)-linked respiration and tended to increase ADP sensitivity, consistent with previous findings in patients with end-stage OA. The decrease in CI-linked respiration was accompanied with lower CI protein abundance. Rap and Rap+Met did not change mitochondrial H₂O₂ emissions. There were no differences between mitochondrial function in Rap versus Rap+Met suggesting that Rap was likely driving the change in mitochondrial function. This is the first inquiry into how lifespan extending treatments Rap and Rap+Met can influence skeletal muscle mitochondria in a model of age-related OA. Collectively, our data suggest that Rap with or without Met inhibits CI-linked capacity and increases ADP sensitivity in DH guinea pigs that have greater OA severity.ed capacity and increases ADP sensitivity in DH guinea pigs that have greater OA severity.)
• Logan 2018 Thesis  + (A decline in the oxygen cost of exercise e … A decline in the oxygen cost of exercise enhances exercise tolerance and performance. Substantial research has shown that dietary nitrate lowers the oxygen cost of exercise in sedentary humans; however, the metabolic determinants regarding how dietary nitrate influences oxygen consumption in skeletal muscle is not known. We addressed this gap in knowledge by employing a zebrafish (''Danio rerio'') model to study the effect of nitrate and nitrite supplementation. We hypothesize that zebrafish treated with nitrate and nitrite will respond with a decrease in oxygen consumption during exercise. We exposed zebrafish to 606.9 mg/L sodium nitrate (100 mg/L nitrate-nitrogen), 19.5 mg/L sodium nitrite (13 mg/liter nitrite-nitrogen), and control (no treatment) conditions. Using a Sievers Nitric Oxide Analyzer, we confirmed treatment by quantifying nitrate and nitrite levels in fish water before and after treatment, and in fish blood. We subjected these animals to a swim test to determine the effect of nitrate and nitrite treatment on oxygen consumption and found that nitrate exposure decreased, while nitrite exposure increased, the oxygen cost of exercise. To determine whether mitochondrial function could explain the differing effect of nitrate and nitrite on oxygen consumption, we isolated skeletal muscle mitochondria from each group and analyzed oxygen consumption using high resolution respirometry. Isolated mitochondria, exposed to various substrates of respiration exhibited no change in oxygen consumption, or ATP production during uncoupled states of respiration. We found no significant differences in the ratio of ADP:O, or mitochondrial proteins citrate synthase and ATP5A as a result of exposure. Future research will explore other aspects of energy metabolism and utilization to describe mechanisms that explain the differential oxygen consumption observed during nitrate and nitrite treatment.rved during nitrate and nitrite treatment.)
• Kiss 2013 FASEB J  + (A decline in α-ketoglutarate dehydrogenase … A decline in α-ketoglutarate dehydrogenase complex (KGDHC) activity has been associated with neurodegeneration. Provision of succinyl-CoA by KGDHC is essential for generation of matrix ATP (or GTP) by substrate-level phosphorylation catalyzed by succinyl-CoA ligase. Here, we demonstrate ATP consumption in respiration-impaired isolated and ''in situ'' neuronal somal mitochondria from transgenic mice with a deficiency of either dihydrolipoyl succinyltransferase (DLST) or dihydrolipoyl dehydrogenase (DLD) that exhibit a 20-48 % decrease in KGDHC activity. Import of ATP into the mitochondrial matrix of transgenic mice was attributed to a shift in the reversal potential of the adenine nucleotide translocase toward more negative values due to diminished matrix substrate-level phosphorylation, which causes the translocase to reverse prematurely. Immunoreactivity of all three subunits of succinyl-CoA ligase and maximal enzymatic activity were unaffected in transgenic mice as compared to wild-type littermates. Therefore, decreased matrix substrate-level phosphorylation was due to diminished provision of succinyl-CoA. These results were corroborated further by the finding that mitochondria from wild-type mice respiring on substrates supporting substrate-level phosphorylation exhibited ∼30 % higher ADP-ATP exchange rates compared to those obtained from DLST+/- or DLD+/- littermates. We propose that KGDHC-associated pathologies are a consequence of the inability of respiration-impaired mitochondria to rely on "in-house" mitochondrial ATP reserves. on "in-house" mitochondrial ATP reserves.)
• Correa 2017 Crit Care  + (A decrease in blood lactate levels (Lac) & … A decrease in blood lactate levels (Lac) >10% during the first hours of resuscitation in sepsis is associated with better outcomes, but the mechanisms are unclear. Our objective was to investigate the relationship between the time course of Lac, inflammatory response, and mitochondrial respiration during experimental sepsis.</br></br>Original data from two previously published studies were reanalyzed. In cohort 1, pigs were randomized to be resuscitated for 48 h starting at 6, 12, and 24 h, respectively, after fecal peritonitis induction (n = 8 each). Animals were categorized according to the decrease in Lac during the first 6 h of resuscitation (early if ≥10% [Lac ≥10%] or late if <10% or increased [Lac <10%]), and systemic hemodynamics, inflammatory parameters, and mitochondrial function were compared between groups. In a second group of animals with fecal peritonitis and 24 h of resuscitation (n = 16, cohort 2), abdominal regional Lac exchange was measured, and animals were categorized according to the decrease in Lac as in cohort 1.</br></br>Overall mortality was 20% (4 of 20) in the Lac ≥10% group and 60% (12 of 20) in the Lac <10% group (p = 0.022). In cohort 1, systemic hemodynamics were similar in the Lac ≥10% (n = 13) and Lac <10% (n = 11) groups. Plasma interleukin-6 levels increased during unresuscitated sepsis and decreased during resusciation in both groups, but they were lower at study end in the Lac ≥10% group (p = 0.047). Complexes I and II maximal (state 3) and resting (state 4) isolated brain mitochondrial respiration at study end was higher in the Lac ≥10% group than in the Lac <10% group, whereas hepatic, myocardial, and skeletal muscle mitochondrial respiration was similar in both groups. In cohort 2, mesenteric, total hepatic, and renal blood flow at study end was higher in the Lac ≥10% group (n = 7) than in the Lac <10% group (n = 9), despite similar cardiac output. Hepatic lactate influx and uptake in the Lac ≥10% group were approximately 1.5 and 3 times higher, respectively, than in the Lac <10% group (p = 0.066 for both).</br></br>A decrease in Lac >10% during early resuscitation (6 h) after abdominal sepsis is associated with lower levels of plasma interleukin-6 and improved brain but not hepatic or muscle mitochondrial respiration. Blood flow redistribution to abdominal organs in animals with early decrease in Lac concentrations increases the potential to both deliver and extract Lac.ncentrations increases the potential to both deliver and extract Lac.)
• Hervouet 2008 Carcinogenesis  + (A decrease in oxidative phosphorylation (O … A decrease in oxidative phosphorylation (OXPHOS) is characteristic of many cancer types and, in particular, of clear cell renal carcinoma (CCRC) deficient in von Hippel–Lindau (''vhl'') gene. In the absence of functional pVHL, hypoxia-inducible factor (HIF) 1-α and HIF2-α subunits are stabilized, which induces the transcription of many genes including those involved in glycolysis and reactive oxygen species (ROS) metabolism. Transfection of these cells with ''vhl'' is known to restore HIF-α subunit degradation and to reduce glycolytic genes transcription. We show that such transfection with vhl of 786-0 CCRC (which are devoid of HIF1-α) also increased the content of respiratory chain subunits. However, the levels of most transcripts encoding OXPHOS subunits were not modified. Inhibition of HIF2-α synthesis by RNA interference in pVHL-deficient 786-0 CCRC also restored respiratory chain subunit content and clearly demonstrated a key role of HIF in OXPHOS regulation. In agreement with these observations, stabilization of HIF-α subunit by CoCl₂ decreased respiratory chain subunit levels in CCRC cells expressing pVHL. In addition, HIF stimulated ROS production and mitochondrial manganese superoxide dismutase content. OXPHOS subunit content was also decreased by added H₂O₂. Interestingly, desferrioxamine (DFO) that also stabilized HIF did not decrease respiratory chain subunit level. While CoCl₂ significantly stimulates ROS production, DFO is known to prevent hydroxyl radical production by inhibiting Fenton reactions. This indicates that the HIF-induced decrease in OXPHOS is at least in part mediated by hydroxyl radical production.IF-induced decrease in OXPHOS is at least in part mediated by hydroxyl radical production.)
• Callaway 2013 Nature  + (A dedicated website for sharing biology pa … A dedicated website for sharing biology papers before peer review leaves journals divided. What are biologists so afraid of? Physicists, mathematicians and social scientists routinely post their research to preprint servers such as arXiv.org before publication, yet few life scientists follow suit. A website that goes live this week is hoping to change that. The site, bioRχiv.org, launched by Cold Spring Harbor Laboratory Press in New York, bills itself as “the preprint server for biology”. It will operate similarly to arXiv, with scientists depositing papers as soon as they are ready to share them, weeks or months before formal publication.weeks or months before formal publication.)
• Kula 2017 J Photochem Photobiol  + (A density in algal suspension causes a sig … A density in algal suspension causes a significant change in the intensity and spectral composition of light reaching individual cells. Measurements of chlorophyll fluorescence allow us to observe any general changes in the bioenergetic status of photosynthesis. The aim of the study was to determine the effect of cultivation density on the PSII photochemical efficiency of three species of algae (Chlorella vulgaris, Botryococcus braunii and Chlorella emersonii), each with a different rate of growth - high, medium and low - respectively. The cell density of algae in suspension differentiated through the cultivation time (2, 4, and 8days) and the spectral composition of light. The results showed that the density of cultivation led to change in the photosynthetic apparatus of algae. The differences described between each day of cultivation (2, 4, and 8) in the kinetics of chlorophyll a fluorescence intensity in cells of the algal strains under study probably resulted from the different phases of growth of these cultures. In addition the results showed the beneficial effect of far red light on the photosynthetic apparatus and the growth of biomass in investigated algal strains. of biomass in investigated algal strains.)
• Halangk 1997 Zentralbl Chir  + (A disturbed energy metabolism in pancreati … A disturbed energy metabolism in pancreatic acinar cells is discussed as factor contributing to the development of acute pancreatitis (AP). In this study, we investigated to what extent the mitochondrial ATP producing capacity is impaired in the pancreatic tissue of rats with experimental AP. For preparation of mitochondria from rat pancreas, routine isolation procedures (tissue homogenization and differential centrifugation) were applied. Mitochondria were isolated from rats with edematous pancreatitis produced by hyperstimulation with caerulein, and from rats with mild necrotizing acute pancreatitis. The latter form of AP was induced by a temporary occlusion of the biliary pancreatic duct accompanied by a simultaneous intravenous injection of caerulein plus secretin and an intraabdominal administration of ethanol. As functional parameters of oxidative phosphorylation, the respiration rate, the mitochondrial membrane potential, and the activity of the complex I of the respiratory chain were determined. Mitochondria from rats with caerulein AP showed an enhanced respiration (61% vs. saline control) and a diminished membrane potential (-17 mV) if respiring with succinate in the non-phosphorylating state. This indicates an increased proton leak across the mitochondrial inner membrane. In the mild necrotizing AP, mitochondria were characterized by a decreased respiration with NAD(+)-linked substrates (-33% vs. sham-operated animals). This inhibition of respiration was confirmed by the reduced activity measured for the NADH-cytochrome c reductase (-32%). In both models of experimental AP the potency of mitochondria to produce ATP was significantly diminished. The stronger impairment of mitochondrial functions were found in the necrotizing form of AP. Reactive oxygen species may lead to the observed alterations--to the enhanced permeability of the mitochondrial inner membrane as well as to the inhibition of the complex I of the respiratory chain.of the complex I of the respiratory chain.)
• Mizushima 2016 J Mol Cell Cardiol  + (A failing heart shows severe energy insuff … A failing heart shows severe energy insufficiency, and it is presumed that this energy shortage plays a critical role in the development of cardiac dysfunction. However, little is known about the mechanisms that cause energy metabolic alterations in the failing heart. Here, we show that the novel RING-finger protein 207 (RNF207), which is specifically expressed in the heart, plays a role in cardiac energy metabolism. Depletion of RNF207 in neonatal rat cardiomyocytes (NRCs) leads to a reduced cellular concentration of adenosine triphosphate (ATP) and mitochondrial dysfunction. Consistent with this result, we observed here that the expression of RNF207 was significantly reduced in mice with common cardiac diseases including heart failure. Intriguingly, proteomic approaches revealed that RNF207 interacts with the voltage-dependent anion channel (VDAC), which is considered to be a key regulator of mitochondria function, as an RNF207-interacting protein. Our findings indicate that RNF207 is involved in ATP production by cardiomyocytes, suggesting that RNF207 plays an important role in the development of heart failure. role in the development of heart failure.)
• Fridovich 1997 J Biol Chem  + (A field of inquiry may be said to have com … A field of inquiry may be said to have come of age when conclusions initially viewed as remarkable or even unbelievable are accepted as commonplace. Study of the biology of the superoxide anion radical and of related free radicals, and the defenses thereto, has now reached this happy state of maturity. Superoxide and even hydroxyl radicals are now known to be produced in living systems, and elaborate systems of defense and repair, which minimize the ravages of these reactive species, have been described. New members of the superoxide dismutase, catalase, and peroxidase families of defensive enzymes are being found, as are new targets that are modified by O·̄2. In addition, the involvement of O·̄2 in both physiological and pathological processes is being established. A weighty tome would be needed to encompass a comprehensive coverage of this field of study. This review will describe only aspects of the biology of oxygen radicals that currently engage the interest of the writer. Hopefully they will also be of interest to the reader. Other recent reviews may serve to fill the gaps in this one.ws may serve to fill the gaps in this one.)
• Klosterhoff 2017 Int J Biol Macromol  + (A fraction composed of an arabinan-rich pe … A fraction composed of an arabinan-rich pectin was extracted from acerola fruit (''Malpighia emarginata'') and named ACWS. This fraction presented 93% of total carbohydrate, relative molecular weight of 7.5×10⁴g/mol, galacturonic acid, arabinose, galactose, xylose and rhamnose in 52.1:32.4:7.2:4.8:3.5 molar ratio and had its structure confirmed by NMR analysis. The anti-fatigue activity of ACWS was evaluated using the weight load swim test on trained mice. ACWS was orally administered at doses of 50mg/kg, 100mg/kg and 200mg/kg for 28days. Plasma biochemical parameters, respiration of permeabilized skeletal muscle fibers, and GSH levels and lipoperoxidation in the brain (pre-frontal cortex, hippocampus, striatum and hypothalamus) were determined. ACWS could lengthen the swimming time, increase the plasma levels of glucose, triglycerides, lactate, and the GSH levels in the hippocampus at all tested doses. The mitochondrial respiratory capacity of the skeletal muscle was increased at middle and high ACWS doses. This study provides strong evidence that ''M. emarginata'' pectic polysaccharide supplementation has anti-fatigue activity, can modify the kinetics of energy substrates (carbohydrate and fat) mobilization and the respiratory capacity of the skeletal muscle, as well the antioxidant status in the hippocampus of ACWS treated animals.ant status in the hippocampus of ACWS treated animals.)
• Ejarque 2018 Int J Obes (Lond)  + (A functional population of adipocyte precu … A functional population of adipocyte precursors, termed adipose-derived stromal/stem cells (ASCs), is crucial for proper adipose tissue (AT) expansion, lipid handling, and prevention of lipotoxicity in response to chronic positive energy balance. We previously showed that obese human subjects contain a dysfunctional pool of ASCs. Elucidation of the mechanisms underlying abnormal ASC function might lead to therapeutic interventions for prevention of lipotoxicity by improving the adipogenic capacity of ASCs.</br></br>Using epigenome-wide association studies, we explored the impact of obesity on the methylation signature of human ASCs and their differentiated counterparts. Mitochondrial phenotyping of lean and obese ASCs was performed. ''TBX15'' loss- and gain-of-function experiments were carried out and western blotting and electron microscopy studies of mitochondria were performed in white AT biopsies from lean and obese individuals.</br></br>We found that DNA methylation in adipocyte precursors is significantly modified by the obese environment, and adipogenesis, inflammation, and immunosuppression were the most affected pathways. Also, we identified ''TBX15'' as one of the most differentially hypomethylated genes in obese ASCs, and genetic experiments revealed that ''TBX15'' is a regulator of mitochondrial mass in obese adipocytes. Accordingly, morphological analysis of AT from obese subjects showed an alteration of the mitochondrial network, with changes in mitochondrial shape and number.</br></br>We identified a DNA methylation signature in adipocyte precursors associated with obesity, which has a significant impact on the metabolic phenotype of mature adipocytes. metabolic phenotype of mature adipocytes.)
• Gasmi 2021 Arch Toxicol  + (A fundamental metabolic feature of cancero … A fundamental metabolic feature of cancerous tissues is high glucose consumption. The rate of glucose consumption in a cancer cell can be 10-15 times higher than in normal cells. Isolation and cultivation of tumor cells in vitro highlight properties that are associated with intensive glucose utilization, the presence of minimal oxidative metabolism, an increase in lactate concentrations in the culture medium and a reduced rate of oxygen consumption. Although glycolysis is suggested as a general feature of malignant cells and recently identified as a possible contributing factor to tumor progression, several studies highlight distinct metabolic characteristics in some tumors, including a relative decrease in avidity compared to glucose and/or a glutamine dependency of lactate and even proliferative tumor cells. The aim of this review is to determine the particularities in the energy metabolism of cancer cells, focusing on the main nutritional substrates, such as glucose and glutamine, evaluating lactate dehydrogenase as a potential marker of malignancy and estimating activators and inhibitors in cancer treatment.vators and inhibitors in cancer treatment.)
• Freyer 2012 Nat Genet  + (A genetic bottleneck explains the marked c … A genetic bottleneck explains the marked changes in mitochondrial DNA (mtDNA) heteroplasmy that are observed during the transmission of pathogenic mutations, but the precise timing of these changes remains controversial, and it is not clear whether selection has a role. These issues are important for the genetic counseling of prospective mothers and for the development of treatments aimed at disease prevention. By studying mice transmitting a heteroplasmic single-base-pair deletion in the mitochondrial tRNA(Met) gene, we show that the extent of mammalian mtDNA heteroplasmy is principally determined prenatally within the developing female germline. Although we saw no evidence of mtDNA selection prenatally, skewed heteroplasmy levels were observed in the offspring of the next generation, consistent with purifying selection. High percentages of mtDNA genomes with the tRNA(Met) mutation were linked to a compensatory increase in overall mitochondrial RNA levels, ameliorating the biochemical phenotype and explaining why fecundity is not compromised.plaining why fecundity is not compromised.)
• Chawla 2017 Nature  + (A geneticist's decision not to publish his … A geneticist's decision not to publish his finalized preprint in a journal gets support from scientists online. Preprint papers posted on servers such as [[arXiv]] and [[bioRxiv]] are designed to get research results out for discussion before they are formally peer reviewed and published in journals. But for some scientists, the term is now a misnomer — their preprint papers will never be submitted for formal publication.never be submitted for formal publication.)
• Munro 2022 Mitochondrion  + (A greater capacity of endogenous matrix an … A greater capacity of endogenous matrix antioxidants has recently been hypothesized to characterize mitochondria of long-lived species, curbing bursts of reactive oxygen species (ROS) generated in this organelle. Evidence for this has been obtained from studies comparing the long-lived naked mole rat to laboratory mice. We tested this hypothesis by comparing the longest-lived metazoan, the marine bivalve ''Arctica islandica'' (MLSP=507 y), with shorter-lived and evolutionarily related species. We used a recently developed fluorescent technique to assess mantle and gill tissue mitochondria's capacity to consume hydrogen peroxide (H₂O₂) in multiple physiological states ''ex vivo''. Depending on the type of respiratory substrate provided, mitochondria of ''Arctica islandica'' could consume between 3-14 times more H₂O₂ than shorter-lived species. These findings support the contention that a greater capacity for the elimination of ROS characterizes long-lived species, a novel property of mitochondria thus far demonstrated in two key biogerontological models from distant evolutionary lineages.s far demonstrated in two key biogerontological models from distant evolutionary lineages.)
• Goalstone 2010 Biochemical and Biophysical Research Communication  + (A growing body of evidence implicates smal … A growing body of evidence implicates small G-proteins [e.g., Cdc42 and Rac1] in glucose-stimulated insulin secretion [GSIS] in the islet beta-cell. These signaling proteins undergo post-translational modifications [e.g., prenylation] at their C-terminal cysteine residue and appear to be essential for the transport and fusion of insulin-containing secretory granules with the plasma membrane and the exocytotic secretion of insulin. However, potential regulation of the prenylating enzymes by physiological insulin secretogues [e.g., glucose] has not been investigated thus far. Herein, we report immunological localization, sub-cellular distribution and regulation of farnesyltransferases [FTases] and geranylgeranyltransferase [GGTase] by glucose in insulin-secreting INS 832/13 beta-cells and normal rat islets. Our findings suggest that an insulinotropic concentration of glucose [20mM] markedly stimulated the expression of the alpha-subunits of FTase/GGTase-1, but not the beta-subunits of FTase or GGTase-1 without significantly affecting the predominantly cytosolic distribution of these holoenzymes in INS 832/13 cells and rodent islets. Under these conditions, glucose significantly stimulated [2.5- to 4.0-fold over basal] the activities of both FTase and GGTase-1 in both cell types. Together, these findings provide the first evidence to suggest that GSIS involves activation of the endogenous islet prenyltransferases by glucose, culminating in the activation of their respective G-protein substrates, which is necessary for cytoskeletal rearrangement, vesicular transport, fusion and secretion of insulin.ransport, fusion and secretion of insulin.)
• Borutaite MiP2010  + (A growing body of evidence suggests that n … A growing body of evidence suggests that neurodegeneration in Alzheimer‘s disease (AD) is related to extracellular and intracellular accumulation of amyloid beta peptide (Aβ), mitochondrial dysfunction, increased neuronal loss, however the molecular pathways from Aβ to the main pathological hallmarks of AD are still elusive. Aβ molecules tend to aggregate and form complexes of varying size - from small soluble oligomers, bigger protofibrils and large insoluble fibrils. It is commonly assumed that formation of Aβ fibrils is the crucial event in the pathogenesis of AD. However, there is accumulating evidence that soluble oligomers are the most cytotoxic forms of Aβ though it is still unclear particles of which size and morphology exert most neurotoxicity. In our study we aimed to investigate a link between the size of soluble Aβ oligomers and their toxicity to rat cerebellar granule cells (CGC), cortical neurons and other non-neuronal cells. Variation in conditions during ''in vitro'' oligomerization of Aβ1-42 resulted in peptide assemblies with different particle size. Small oligomeric forms of Aβ1-42 with a particle z-height of 1-2 nm (as measured by atomic force microscopy) were found to be the most toxic species, inducing rapid neuronal necrosis at submicromolar concentrations, whereas the bigger aggregates (above 4-5 nm) did not cause detectable neuronal death. Aβ1-42 oligomers, monomers and fibrils were non-toxic to glial cells in CGC cultures or macrophage J774 cells. Small oligomers of Aβ exhibited tendency to bind to the phospholipid vesicles which composition was similar to reported neuronal plasma membrane composition. In contrast, bigger, non-toxic oligomers did not bind to phospholipid vesicles.</br></br>We also found that mitochondrial respiratory functions were not affected by Aβ1-42 irrespective of the aggregate state: monomers, oligomers or fibrils of Aβ at concentrations up to 2 µM did not inhibit state 3 and state 4 respiration of isolated brain mitochondria and did not cause permeabilization of mitochondrial outer membrane as measured by the exogenous cytochrome c test on mitochondrial respiration. This suggests that Aβ1-42 at pathophysiologically relevant concentrations has no acute effect on mitochondria.</br></br>In conclusion, our data demonstrate that small oligomers of Aβ at submicromolar concentrations induce rapid neuronal necrosis most likely due to the effect on neuronal plasma membranes, whereas bigger aggregates are not directly toxic to neurons.regates are not directly toxic to neurons.)
• Mu 2022 Biochim Biophys Acta Mol Basis Dis  + (A growing body of evidence supports a role … A growing body of evidence supports a role of the gut microbiota in regulating diverse physiological processes, including neural function and metabolism via the gut-brain axis. Infantile spasms syndrome is an early-onset epileptic encephalopathy associated with perturbed brain mitochondrial bioenergetics. Employing a neonatal rat model of infantile spasms, mitochondria respirometry and biochemical analyses, the present study reveals that gut microbiota manipulation by diet, antibiotics and probiotics have the potential to enhance hippocampal mitochondrial bioenergetics. Although preliminary in nature, our data reveal that microbial manipulation that regulates brain mitochondrial function may be a novel strategy for the treatment of epileptic disorders. for the treatment of epileptic disorders.)
• Perry 2013 Diabetes  + (A growing body of research is investigatin … A growing body of research is investigating the potential contribution of mitochondrial function to the etiology of type 2 diabetes. Numerous ''in vitro'', in situ, and ''in vivo'' methodologies are available to examine various aspects of mitochondrial function, each requiring an understanding of their principles, advantages, and limitations. This review provides investigators with a critical overview of the strengths, limitations and critical experimental parameters to consider when selecting and conducting studies on mitochondrial function. ''In vitro'' (isolated mitochondria) and in situ (permeabilized cells/tissue) approaches provide direct access to the mitochondria, allowing for study of mitochondrial bioenergetics and redox function under defined substrate conditions. Several experimental parameters must be tightly controlled, including assay media, temperature, oxygen concentration, and in the case of permeabilized skeletal muscle, the contractile state of the fibers. Recently developed technology now offers the opportunity to measure oxygen consumption in intact cultured cells. Magnetic resonance spectroscopy provides the most direct way of assessing mitochondrial function ''in vivo'' with interpretations based on specific modeling approaches. The continuing rapid evolution of these technologies offers new and exciting opportunities for deciphering the potential role of mitochondrial function in the etiology and treatment of diabetes.in the etiology and treatment of diabetes.)
• Ludzki 2014 Thesis  + (A hallmark of improved metabolic control i … A hallmark of improved metabolic control is a reduced free ADP requirement for</br>a given workload (increased ADP sensitivity). In contrast to ''in vivo'' data, </br>in situ assessments suggest that mitochondrial ADP sensitivity is decreased following exercise training, implying external regulat ion that is not recapitulated in situ. One previously unexplored regulator is palmitoyl-CoA (P-</br>CoA), a lipid metabolism intermediate that inhibits the mitochondrial ADP transport protein adenine nucleotide transferase (ANT). This thesis: 1) established reduced mitochondrial ADP sensitivity following exercise training</br>in middle aged males using permeabilized muscle fibre bundles (PmFB), 2) determined a methodology to evaluate ADP kinetics in PmFB in the presence of P</br>-CoA, and 3) found increased mitochondrial ADP sensitivity in the presence of P</br>-CoA following training. These data suggest that P- CoA is a key regulator of oxidative phosphorylation and direct future exploration of mitochondrial function towards the control of ADP transport via ANT and the effects of exercise on the P-CoA-ANT interaction. of exercise on the P-CoA-ANT interaction.)
• Rowley 2017 J Nutr Biochem  + (A hallmark of type 2 diabetes (T2D) is β-c … A hallmark of type 2 diabetes (T2D) is β-cell dysfunction and the eventual loss of functional β-cell mass. Therefore, mechanisms that improve or preserve β-cell function could be used to improve the quality of life of individuals with T2D. Studies have shown that monomeric, oligomeric and polymeric cocoa flavanols have different effects on obesity, insulin resistance and glucose tolerance. We hypothesized that these cocoa flavanols may have beneficial effects on β-cell function. INS-1 832/13-derived β-cells and primary rat islets cultured with a monomeric catechin-rich cocoa flavanol fraction demonstrated enhanced glucose-stimulated insulin secretion, while cells cultured with total cocoa extract and with oligomeric or polymeric procyanidin-rich fraction demonstrated no improvement. The increased glucose-stimulated insulin secretion in the presence of the monomeric catechin-rich fraction corresponded with enhanced mitochondrial respiration, suggesting improvements in β-cell fuel utilization. Mitochondrial complex III, IV and V components are up-regulated after culture with the monomer-rich fraction, corresponding with increased cellular ATP production. The monomer-rich fraction improved cellular redox state and increased glutathione concentration, which corresponds with nuclear factor, erythroid 2 like 2 (Nrf2) nuclear localization and expression of Nrf2 target genes including nuclear respiratory factor 1 (Nrf1) and GA binding protein transcription factor alpha subunit (GABPA), essential genes for increasing mitochondrial function. We propose a model by which monomeric cocoa catechins improve the cellular redox state, resulting in Nrf2 nuclear migration and up-regulation of genes critical for mitochondrial respiration, glucose-stimulated insulin secretion and ultimately improved β-cell function. These results suggest a mechanism by which monomeric cocoa catechins exert their effects as an effective complementary strategy to benefit T2D patients.</br></br>Copyright © 2017 Elsevier Inc. All rights reserved. © 2017 Elsevier Inc. All rights reserved.)
• Rowley 2017 Thesis  + (A hallmark of type 2 diabetes (T2D) is β-c … A hallmark of type 2 diabetes (T2D) is β-cell dysfunction and the eventual loss of functional β-cell mass. Therefore, mechanisms that improve or preserve β-cell function could be used to improve the quality of life of individuals with T2D. Studies have shown that monomeric, oligomeric and polymeric cocoa flavanols have different effects on obesity, insulin resistance and glucose tolerance. We hypothesized that these cocoa flavanols may have beneficial effects on β-cell function. INS-1 832/13 derived β-cells and primary rat islets cultured with a monomeric catechin-rich cocoa flavanol fraction demonstrated enhanced glucose-stimulated insulin secretion, while cells cultured with total cocoa extract, oligomeric, or polymeric procyanidin-rich fractions demonstrated no improvement. The increased glucose-stimulated insulin secretion in the presence of the monomeric catechin-rich fraction corresponded with enhanced mitochondrial respiration, suggesting improvements in β-cell fuel utilization. Mitochondrial complex III, IV and V components were upregulated after culture with the monomer-rich fraction, corresponding with increased cellular ATP production. The monomer-rich fraction improved cellular redox state and increased glutathione concentration, which corresponds with Nrf2 nuclear localization and expression of Nrf2 target genes, including NRF-1 and GABPA, essential genes for increasing mitochondrial function. We propose a model by which monomeric cocoa catechins improve the cellular redox state, resulting in Nrf2 nuclear migration and upregulation of genes critical for mitochondrial respiration, and, ultimately, enhanced glucose-stimulated insulin secretion and β-cell function. These results suggest a mechanism by which monomeric cocoa catechins exert their effects as an effective complementary strategy to benefit T2D patients.ementary strategy to benefit T2D patients.)
• Hoeks 2008 FEBS Lett  + (A high intake of dietary fat has been sugg … A high intake of dietary fat has been suggested to diminish mitochondrial functioning in skeletal muscle, possibly attributing to muscular fat accumulation. Here we show however, that an 8-week high-fat dietary intervention did not affect intrinsic functioning of rat skeletal muscle mitochondria assessed by respirometry, neither on a carbohydrate- nor on a lipid-substrate. Interestingly, PPARGC1A protein increased by approximately 2-fold upon high-fat feeding and we observed inconsistent results on different markers of mitochondrial density. Mitochondrial ROS production, assessed by electron spin resonance spectroscopy remained unaffected. Intramyocellular lipid levels increased significantly illustrating that a reduced innate mitochondrial function is not a prerequisite for intra-muscular fat accumulation.isite for intra-muscular fat accumulation.)
• Park 2017 Metab Brain Dis  + (A high-fat diet induces obesity in mice, l … A high-fat diet induces obesity in mice, leading to insulin resistance, decreased mitochondrial function, and increased apoptosis in the hippocampus, which eventually result in memory loss. The present study investigated the effect of physical exercise on memory, hippocampal mitochondrial function, and apoptosis in mice with in insulin resistance caused by obesity due to high-fat diet. Mice were randomly divided into four groups: control (CON), control and exercise (CON + EX), high fat diet (HFD), and high fat diet and exercise (HFD + EX). After receiving a high-fat (60%) diet for 20 weeks to induce obesity, the animals were subjected to an exercise routine 6 times per week, for 12 weeks. The exercise duration and intensity gradually increased over 4-week intervals. Hippocampal memory was examined using the step-down avoidance task. Mitochondrial function and apoptosis were also examined in the hippocampus and dentate gyrus. We found that obesity owing to a high-fat diet induced insulin resistance and caused a decrease in memory function. Insulin resistance also caused a decrease in mitochondrial function in the hippocampus by reducing Ca²⁺ retention and O₂, respiration, increasing the levels of H₂O₂, and Cyp-D, and mPTP opening. In addition, apoptosis in the hippocampus increased owing to decreased expression of Bcl-2 and increased expression of Bax, cytochrome c, and caspase-3 and TUNEL-positive cells. In contrast, physical exercise led to reduced insulin resistance, improved mitochondrial function, and reduced apoptosis in the hippocampus. The results suggest that physiological stimulations such as exercise improve hippocampal function and suppress apoptosis, potentially preventing the memory loss associated with obesity-induced insulin resistance.potentially preventing the memory loss associated with obesity-induced insulin resistance.)
• Kwon 2009 Thesis  + (A high-fat diet leads to an accumulation o … A high-fat diet leads to an accumulation of lipid in skeletal muscle, and the development of both mitochondrial dysfunction and insulin resistance. Recently, our lab reported that lipid overload leads to elevated H₂O₂ emission from muscle mitochondria, and that mitochondrial-targeted scavenging of H₂O₂ completely prevents the development of high fat diet-induced insulin resistance. These findings raise the possibility that interventions which acutely restore cellular metabolic balance in muscle may also acutely restore insulin sensitivity. We hypothesized that mitochondrial function and insulin sensitivity can be restored in skeletal muscle of high-fat fed rats by creating an acute deficit in metabolic balance via 2 h low-intensity treadmill exercise or 16 h fasting. Male Sprague-Dawley rats (125-150g) were either maintained on a standard high carbohydrate- diet or fed a high-fat (60%) diet for 6 weeks and divided into three groups the day before the study: one group was maintained on the normal high-fat diet, another group was fasted overnight (16 h), and a third group completed a single 2 h bout of low-intensity treadmill exercise (10 m/min) and then were given normal overnight ad libitum access to the high-fat diet. Oral glucose tolerance tests were administrated to assess insulin action. Red gastrocnemius muscles were harvested and permeabilized fibers prepared for determination of mitochondrial respiratory function and H₂O₂ emission. A single 16 h fast significantly (P<0.05) improved insulin sensitivity in rats maintained on a high-fat diet (P<0.05). Oxygen consumption rate in permeabilized fibers in response to submaximal and maximal ADP concentration when supported exclusively with complex I substrates were not different among groups. However, when respiration was supported by fatty acids (palmitoylcarnitine plus malate, complex I + II substrates), high-fat diet plus exercise group showed higher (P<0.05) rates compared with high-fat diet group. There were no significant differences in H₂O₂ emission among the 4 groups. In conclusion, a single 16 h overnight fast is sufficient to restore insulin sensitivity in high fat diet-induced insulin resistant rats, providing evidence that insulin action in muscle is acutely sensitive to the metabolic state of cells. A single bout of low-intensity treadmill exercise in high-fat fed rats failed to restore insulin action but increased ADP-stimulated respiratory capacity, providing evidence of an as yet unidentified regulatory mechanism of the respiratory system. Somewhat surprisingly however, neither fasting nor exercise altered the H₂O₂ emitting potential in permeabilized fibers, suggesting that further work is required to better understand the factors influencing mitochondrial function and their potential link to insulin sensitivity.lized fibers, suggesting that further work is required to better understand the factors influencing mitochondrial function and their potential link to insulin sensitivity.)
• Cavadas 2015 Hum Mutat  + (A high-resolution mtDNA phylogenetic tree … A high-resolution mtDNA phylogenetic tree allowed us to look backward in time to investigate purifying selection. Purifying selection was very strong in the last 2,500 years, continuously eliminating pathogenic mutations back until the end of the Younger Dryas (∼11,000 years ago), when a large population expansion likely relaxed selection pressure. This was preceded by a phase of stable selection until another relaxation occurred in the out-of-Africa migration. Demography and selection are closely related: expansions led to relaxation of selection and higher pathogenicity mutations significantly decreased the growth of descendants. The only detectible positive selection was the recurrence of highly pathogenic nonsynonymous mutations (m.3394T>C-m.3397A>G-m.3398T>C) at interior branches of the tree, preventing the formation of a dinucleotide STR (TATATA) in the MT-ND1 gene. At the most recent time scale in 124 mother-children transmissions, purifying selection was detectable through the loss of mtDNA variants with high predicted pathogenicity. A few haplogroup-defining sites were also heteroplasmic, agreeing with a significant propensity in 349 positions in the phylogenetic tree to revert back to the ancestral variant. This nonrandom mutation property explains the observation of heteroplasmic mutations at some haplogroup-defining sites in sequencing datasets, which may not indicate poor quality as has been claimed.</br></br>© 2015 WILEY PERIODICALS, INC.s has been claimed. © 2015 WILEY PERIODICALS, INC.)
• Djafarzadeh 2017 J Vis Exp  + (A high-resolution oxygraph is a device for … A high-resolution oxygraph is a device for measuring cellular oxygen consumption in a closed-chamber system with very high resolution and sensitivity in biological samples (intact and permeabilized cells, tissues or isolated mitochondria). The high-resolution oxygraph device is equipped with two chambers and uses polarographic oxygen sensors to measure oxygen concentration and calculate oxygen consumption within each chamber. Oxygen consumption rates are calculated using software and expressed as picomoles per second per number of cells. Each high-resolution oxygraph chamber contains a stopper with injection ports, which makes it ideal for substrate-uncoupler-inhibitor titrations or detergent titration protocols for determining effective and optimum concentrations for plasma membrane permeabilization. The technique can be applied to measure respiration in a wide range of cell types and also provides information on mitochondrial quality and integrity, and maximal mitochondrial respiratory electron transport system capacity.ratory electron transport system capacity.)
• Hatefi 1961 Biochim Biophys Acta  + (A highly active DPNH-cytochrome c reductas … A highly active DPNH-cytochrome c reductase has been isolated from beef-heart mitochondria. The best preparations of the enzyme catalyze the reduction by DPNH of approx. 50–60 μmoles cytochrome c/min/mg protein at 38°. The enzymic activity is completely inhibited by Amytal, p-chloromercuriphenyl sulfonate, antimycin A, SN-5949 or 2-nonyl-4-hydroxyquinoline-N-oxide, and is stimulated by EDTA. The preparation contains DPNH flavoprotein, cytochromes b and c1, Coenzyme Q and non-heme iron and is essentially free of succinic-cytochrome c reductase as well as cytochrome oxidase activity.se as well as cytochrome oxidase activity.)
• Kotarsky 2010 Mitochondrion  + (A homozygous mutation in the complex III c … A homozygous mutation in the complex III chaperone BCS1L causes GRACILE syndrome (intrauterine growth restriction, aminoaciduria, cholestasis, hepatic iron overload, lactacidosis). In control and patient fibroblasts we localized BCS1L in inner mitochondrial membranes. In patient liver, kidney, and heart BCS1L and Rieske protein levels, as well as the amount and activity of complex III, were decreased. Major histopathology was found in kidney and liver with cirrhosis and iron deposition, but of iron-related proteins only ferritin levels were high. In placenta from a GRACILE fetus, the ferrooxidases ceruloplasmin and hephaestin were upregulated suggesting association between iron overload and placental dysfunction.n iron overload and placental dysfunction.)
• Stodden 2020 Proc Natl Acad Sci U S A  + (A key component of scientific communicatio … A key component of scientific communication is sufficient information for other researchers in the field to reproduce published findings. For computational and data-enabled research, this has often been interpreted to mean making available the raw data from which results were generated, the computer code that generated the findings, and any additional information needed such as workflows and input parameters. Many journals are revising author guidelines to include data and code availability. This work evaluates the effectiveness of journal policy that requires the data and code necessary for reproducibility be made available postpublication by the authors upon request. We assess the effectiveness of such a policy by (i) requesting data and code from authors and (ii) attempting replication of the published findings. We chose a random sample of 204 scientific papers published in the journal Science after the implementation of their policy in February 2011. We found that we were able to obtain artifacts from 44 % of our sample and were able to reproduce the findings for 26 %. We find this policy—author remission of data and code postpublication upon request—an improvement over no policy, but currently insufficient for reproducibility.urrently insufficient for reproducibility.)
• Nissen 2017 Glia  + (A key enzyme in brain glutamate homeostasi … A key enzyme in brain glutamate homeostasis is glutamate dehydrogenase (GDH) which links carbohydrate and amino acid metabolism mediating glutamate degradation to CO2 and expanding tricarboxylic acid (TCA) cycle capacity with intermediates, i.e. anaplerosis. Humans express two GDH isoforms, GDH1 and 2, whereas most other mammals express only GDH1. hGDH1 is widely expressed in human brain while hGDH2 is confined to astrocytes. The two isoforms display different enzymatic properties and the nature of these supports that hGDH2 expression in astrocytes potentially increases glutamate oxidation and supports the TCA cycle during energy-demanding processes such as high intensity glutamatergic signaling. However, little is known about how expression of hGDH2 affects the handling of glutamate and TCA cycle metabolism in astrocytes. Therefore, we cultured astrocytes from cerebral cortical tissue of hGDH2-expressing transgenic mice. We measured glutamate uptake and metabolism using [3 H]glutamate, while the effect on metabolic pathways of glutamate and glucose was evaluated by use of 13 C and 14 C substrates and analysis by mass spectrometry and determination of radioactively labeled metabolites including CO2 , respectively. We conclude that hGDH2 expression increases capacity for uptake and oxidative metabolism of glutamate, particularly during increased workload and aglycemia. Additionally, hGDH2 expression increased utilization of branched-chain amino acids (BCAA) during aglycemia and caused a general decrease in oxidative glucose metabolism. We speculate, that expression of hGDH2 allows astrocytes to spare glucose and utilize BCAAs during substrate shortages. These findings support the proposed role of hGDH2 in astrocytes as an important fail-safe during situations of intense glutamatergic activity.uations of intense glutamatergic activity.)
• Andziak 2006 Aging Cell  + (A key tenet of the oxidative stress theory … A key tenet of the oxidative stress theory of aging is that levels of accrued oxidative damage increase with age. Differences in damage generation and accumulation therefore may underlie the natural variation in species longevity. We compared age-related profiles of whole-organism lipid peroxidation (urinary isoprostanes) and liver lipid damage (malondialdehyde) in long living naked mole-rats [maximum lifespan (MLS) > 28.3 years] and shorter-living CB6F1 hybrid mice (MLS approximately 3.5 years). In addition, we compared age-associated changes in liver non-heme iron to assess how intracellular conditions, which may modulate oxidative processes, are affected by aging. Surprisingly, even at a young age, concentrations of both markers of lipid peroxidation, as well as of iron, were at least twofold (P < 0.005) greater in naked mole tats than in mice. This refutes the hypothesis that prolonged naked mole-rat longevity is due to superior protection against oxidative stress. The age-related profiles of all three parameters were distinctly species specific. Rates of lipid damage generation in mice were maintained throughout adulthood, while accrued damage in old animals was twice that of young mice. In naked mole-rats, urinary isoprostane excretion declined by half with age (P < 0.001), despite increases in tissue iron (P < 0.05). Contrary to the predictions of the oxidative stress theory, lipid damage levels did not change with age in mole-rats. These data suggest that the patterns of age-related changes in levels of markers of oxidative stress are species specific, and that the pronounced longevity of naked mole-rats is independent of oxidative stress parameters.le-rats is independent of oxidative stress parameters.)
• Cottingham 1983 Biochim Biophys Acta  + (A kinetic analysis of oxygen uptake was ca … A kinetic analysis of oxygen uptake was carried out in order to investigate the role of ubiquinone pool behaviour in plant mitochondria. The interaction of the external NADH dehydrogenase with either the cytochrome system or the cyanide-insensitive oxidase was examined under various conditions. The involvement of a ubiquinone pool can be deduced from the shape of the titration curve as the appropriate oxidase system is inhibited, by antimycin A for the cytochrome system and salicylhydroxamic acid for the cyanide-insensitive oxidase, at different activities of the NADH dehydrogenase. In the absence of a specific inhibitor, the turnover of the external NADH dehydrogenase was adjusted using a novel NADH-generating system involving the recycling of a low concentration of NAD+ by added glucose 6-phosphate dehydrogenase in the presence of substrate. The results show that ubiquinone pool behaviour is observed between the external NADH dehydrogenase and either the cytochrome b-c1 complex or the cyanide-insensitive oxidase. However, there is a substantial departure from pool behaviour during the simultaneous operation of both oxidases.e simultaneous operation of both oxidases.)
• Laner 2017 Abstract EUROMIT2017 Cologne  + (A lack of physical activity associates wit … A lack of physical activity associates with decreased mitochondrial capacity and is a major cause underlying metabolic dysregulation and preventable diseases in modern societies. In contrast, an active lifestyle supports enhanced mitochondrial capacities and reduces the risk of degenerative diseases. Despite this well-known relation between health and mitochondrial function, there is no regimented, quantitative system, or database organised to routinely test, compare and monitor mitochondrial capacities within individuals or populations. Every study of mitochondrial (mt) function and disease in human tissues and cells is faced with Evolution, Age, Gender, Lifestyle and Environment ([[EAGLE]]) as essential background conditions characterizing the individual patient, subject, study group, species, tissue or – to some extent - cell line. Only a large and well-coordinated network can manage to generate the necessary number of consistent data to address the complexity of EAGLE. Using [[high-resolution respirometry]], the [[K-Regio MitoFit]] and [[MitoEAGLE]] initiatives develop novel lab standards and diagnostic methods for monitoring of a mitochondrial fitness score. SOPs are elaborated for sample preparation, respiratory evaluation and data documentation. Fresh and cryopreserved cells obtained non-invasively from blood samples broaden the scope for respirometric mitochondrial diagnosis.for respirometric mitochondrial diagnosis.)
• Gnaiger 2016 Abstract EBEC Riva del Garda 2016  + (A lack of physical activity associates wit … A lack of physical activity associates with decreased mitochondrial capacity and is a major cause underlying metabolic dysregulation and preventable diseases in modern societies. In contrast, an active lifestyle supports enhanced mitochondrial capacities and reduces the risk of degenerative diseases. Despite this well-known relation between health and mitochondrial function, there is no regimented, quantitative system, or database organised to routinely test, compare and monitor mitochondrial capacities within individuals or populations. Using high-resolution respirometry, the MitoFit and MitoEAGLE initiatives will develop novel lab standards and diagnostic methods for the monitoring of a mitochondrial fitness score. To this end, SOPs will be worked out regarding sample preparation, respiratory evaluation and data documentation. Fresh and cryopreserved cells obtained noninvasively from blood samples will serve as models, the latter allowing samples to be collected for later analysis, thereby broadening the scope for respirometric investigations.</br>This approach will then be expanded to all sorts of human tissues and cells of interest and assess aspects relating to Evolution, Age, Gender, Lifestyle and Environment (EAGLE) as essential background conditions characterizing the individual patient, subject, study group, and/or species. The huge scope of this endeavour requires an international network of laboratories capable of generating the necessary number of consistent data to address the complexity of EAGLE. Coping with the mass of the expected data necessitates a dedicated MitoEAGLE knowledge management network developing harmonization protocols towards generating a rigorously monitored data repository on mitochondrial respiratory function. The resulting MitoEAGLE data management system will enable to interrelate results of a large number of studies, to interpret pathological phenotypes, and to set results into the multidimensional context of EAGLE.nto the multidimensional context of EAGLE.)
• Lukasiak 2016 Eur J Pharmacol  + (A large conductance potassium (BKCa) chann … A large conductance potassium (BKCa) channel opener, NS1619 (1,3-dihydro-1- [2-hydroxy-5-(trifluoromethyl) phenyl]-5-(trifluoromethyl)-2H-benzimidazole-2-one), is well known for its protective effects against ischemia-reperfusion injury; however, the exact mode of its action remains unclear. The aim of this study was to characterize the effect of NS1619 on endothelial cells. The endothelial cell line EA.hy926, guinea pig hearts and submitochondrial particles isolated from the heart were used. In the isolated guinea pig hearts, which were perfused using the Langendorff technique, NS1619 caused a dose-dependent increase in coronary flow that was inhibited by L-NAME. In EA.hy926 cells, NS1619 also caused a dose-dependent increase in the intracellular calcium ion concentration [Ca(2+)]i, as measured using the FURA-2 fluorescent probe. Moreover, NS1619 decreased the oxygen consumption rate in EA.hy926 cells, as assessed using a Clark-type oxygen electrode. However, when NS1619 was applied in the presence of oligomycin, the oxygen consumption increased. NS1619 also decreased the mitochondrial membrane potential, as measured using a JC-1 fluorescent probe in the presence and absence of oligomycin. Additionally, the application of NS1619 to submitochondrial particles inhibited ATP synthase. In summary, NS1619 has pleiotropic actions on EA.hy926 cells and acts not only as an opener of the BKCa channel in EA.hy926 cells but also as an inhibitor of the respiratory chain component, sarcoplasmic reticulum ATPase, which leads to the release of Ca(2+) from the endoplasmic reticulum. Furthermore, NS1619 has the oligomycin-like property of inhibiting mitochondrial ATP synthase.</br></br>Copyright © 2016 Elsevier B.V. All rights reserved. © 2016 Elsevier B.V. All rights reserved.)
• Sperl 1994 J Inher Metab Dis  + (A large number of enzyme systems are exami … A large number of enzyme systems are examined for the diagnosis of mitochondrial myopathies including the pyruvate dehidrogenase complex, tricarboxylic-acid-cycle enzymes and respiratory chain complexes. This investigation can be carried out in frozen tissue. For the study of oxidative phosphorilation in intact mitochondria, fresh muscle tissue is required, and isolation of mitochondria from large amounts of tissue (at least 500-1000 mg) is necessary. For ethical reason this imposes a serious limitation, especially in paediatric patients. Radiochemical measurements of oxidation rates in various substrates in 600 g supernatant from 100-300 mg amounts of muscle tissue has partly overcome this problem. (Bookelman ''et.al''., 1978). Owing to the low yield, the danger of selective isolation of different mitochondrial populations exists. In addition, since isolated mitochondria removed from their natural environment are more or less unstable, there is a possibility of artefacts. Recently, investigation of saponin-skinned muscle fibers by polarographic methods was reported for cardiac (Veksler ''et. al''., 1987) and human muscle tissue. In such permeabilized fibers, study of mitochondrial respiratory control is possible as in isolated mitochondria but without the disadvantages mentioned above (Letellier ''et.al''., 1992; Kunz ''et.al''., 1993).</br>We investigated saponin-skinned muscle fibers in three patients suspected of a mitochondrial encephalo-myopathy. For our studies we used a specially developed respirometer with a sensitivity ten times higher than the established instruments (Kunz ''et.al''., 1993).ished instruments (Kunz ''et.al''., 1993).)
• Lauterbach 2013 FEBS J  + (A large number of industrially relevant en … A large number of industrially relevant enzymes depend upon nicotinamide cofactors, which are too expensive to be added in stoichiometric amounts. Existing NAD(P)H-recycling systems suffer from low activity, or the generation of side products. H₂-driven cofactor regeneration has the advantage of 100% atom efficiency and the use of H₂ as a cheap reducing agent, in a world where sustainable energy carriers are increasingly attractive. The state of development of H₂-driven cofactor-recycling systems and examples of their integration with enzyme reactions are summarized in this article. The O₂-tolerant NAD⁺-reducing hydrogenase from Ralstonia eutropha is a particularly attractive candidate for this approach, and we therefore discuss its catalytic properties that are relevant for technical applications.t are relevant for technical applications.)
• Santoso 2019 Bioorg Med Chem  + (A library of thirty-two quinolinequinones … A library of thirty-two quinolinequinones (QQs) with various amine substituents at the 6- and 7-positions were synthesised efficiently and in good yields for evaluation as potential anti-tuberculosis agents. ''Mycobacterium tuberculosis'' growth inhibition assays demonstrated that QQs bearing moderate length alkyl chains (i.e. heptylphenylamino- and octylamino-QQs), and aryl groups (i.e. phenylethylamino- and benzylamino-QQs) exhibited encouraging inhibitory activity, while QQ analogue 7-chloro-6-propargylamino-quinoline-5,8-dione (16b) had excellent inhibitory activity (MIC = 8 μM). The cLogP values and redox activities of the QQs were determined, and neither readout correlated with the anti-mycobacterial activities of the compounds. Notwithstanding, mode of action studies of 16b revealed that treatment of ''M. tuberculosis'' with this compound led to activation of NADH-dependent oxygen consumption suggesting a redox cycling mechanism. To this end, the promising anti-mycobacterial activity of several QQs and their ability to perturb oxygen management leading to an uncontrolled respiratory burst, as identified in this work and by others, demonstrates the merit of further optimising the anti-mycobacterial activity of this readily synthesised class of compound.</br></br><small>Copyright © 2019. Published by Elsevier Ltd.</small>right © 2019. Published by Elsevier Ltd.</small>)
• Antonenko 2011 J Biol Chem  + (A limited decrease in mitochondrial membra … A limited decrease in mitochondrial membrane potential can be beneficial for cells, especially under some pathological conditions, suggesting that mild uncouplers (protonophores) causing such an effect are promising candidates for therapeutic uses. The great majority of protonophores are weak acids capable of permeating across membranes in their neutral and anionic forms. In the present study, protonophorous activity of a series of derivatives of cationic rhodamine 19, including dodecylrhodamine (C(12)R1) and its conjugate with plastoquinone (SkQR1), was revealed using a variety of assays. Derivatives of rhodamine B, lacking dissociable protons, showed no protonophorous properties. In planar bilayer lipid membranes, separating two compartments differing in pH, diffusion potential of H(+) ions was generated in the presence of C(12)R1 and SkQR1. These compounds induced pH equilibration in liposomes loaded with the pH probe pyranine. C(12)R1 and SkQR1 partially stimulated respiration of rat liver mitochondria in State 4 and decreased their membrane potential. Also, C(12)R1 partially stimulated respiration of yeast cells but, unlike the anionic protonophore FCCP, did not suppress their growth. Loss of function of mitochondrial DNA in yeast (grande-petite transformation) is known to cause a major decrease in the mitochondrial membrane potential. We found that petite yeast cells are relatively more sensitive to the anionic uncouplers than to C(12)R1 compared with grande cells. Together, our data suggest that rhodamine 19-based cationic protonophores are self-limiting; their uncoupling activity is maximal at high membrane potential, but the activity decreases membrane potentials, which causes partial efflux of the uncouplers from mitochondria and, hence, prevents further membrane potential decrease.vents further membrane potential decrease.)
• Bergeson 1981 West J Med  + (A major international movement is in progr … A major international movement is in progress to extend metrication using the International System of Units. Significantly involved is the field of medicine. Extensive changes adopted abroad now appear in foreign medical literature, and physicians in the United States commonly are unprepared to interpret medical information from abroad because the data are reported in unfamiliar terms. The system has broad immediate and future implications to American physicians.uture implications to American physicians.)
• Fernandes 2012 Am J Hum Genet  + (A major unanswered question regarding the … A major unanswered question regarding the dispersal of modern humans around the world concerns the geographical site of the first human steps outside of Africa. The "southern coastal route" model predicts that the early stages of the dispersal took place when people crossed the Red Sea to southern Arabia, but genetic evidence has hitherto been tenuous. We have addressed this question by analyzing the three minor west-Eurasian haplogroups, N1, N2, and X. These lineages branch directly from the first non-African founder node, the root of haplogroup N, and coalesce to the time of the first successful movement of modern humans out of Africa, ∼60 thousand years (ka) ago. We sequenced complete mtDNA genomes from 85 Southwest Asian samples carrying these haplogroups and compared them with a database of 300 European examples. The results show that these minor haplogroups have a relict distribution that suggests an ancient ancestry within the Arabian Peninsula, and they most likely spread from the Gulf Oasis region toward the Near East and Europe during the pluvial period 55-24 ka ago. This pattern suggests that Arabia was indeed the first staging post in the spread of modern humans around the world.</br></br>Copyright © 2012 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.shed by Elsevier Inc. All rights reserved.)
• Friedrich 2010 Abstract MiP2010  + (A medium of containing high levels of pota … A medium of containing high levels of potassium chloride (KCl) is commonly used when assessing respiratory function of isolated mitochondria from various tissues. However, the measured intracellular [K⁺] in kidney proximal tubular cells is about 60 mM and in cardiac myocytes approximately 130 mM. Therefore, the use of a similar media [K⁺] for all tissues seems unsupported. Here we investigated the effect of different [K⁺] on respiratory function in mitochondria isolated from kidney cortex and heart of healthy male Sprague-Dawley rats.</br></br>Oxygen consumptions and the respiratory control ratios (RCR) were measured using respiratory medias containing [K⁺] of 15, 37, 81, 111 and 146 mM. In all measurements, the media contained (in mM): 1 EGTA, 20 HEPES, 5 MgCl2, 5 KPO4- and 1 g/l bovine serum albumin. pH was adjusted to 7.4 and the osmolarity to 330 mosm/kg HK₂O using a 1:3 ratio of sucrose and mannitol.</br></br>The RCR of kidney cortex mitochondria decreased when the [K⁺] was elevated compared to the media containing 15 mM K⁺ (5.2±0.2 vs. 2.5±0.2, 3.7±0.2, 3.9±0.2, 3.0±0.1, respectively). However, RCR of heart mitochondria was lowest at 37 mM (3.9±0.3) and was highest at 146 mM K⁺ (10.1±0.45). A two-way ANOVA showed that kidney cortex mitochondria have a different sensitivity towards K⁺ compared to heart mitochondria (interaction P<0.05, treatment P<0.05, group P<0.05). Glibenclamide (100 µM), an inhibitor of the ATP-sensitive K⁺ channel, increased RCR in kidney cortex mitochondria at 15 mM K⁺ (+32%), but significantly more at 146 mM K⁺ (+47%). Blockade of the voltage-gated K⁺ channel by 4-aminopyridine (4-AP, 1 mM) together with glibenclamide improved RCR by +73% at 146 mM K⁺. Neither of the applied K⁺-channel blockers had any effect on the RCR of heart mitochondria. Mitochondria swelling at increasing [K⁺] were observed in kidney cortex mitochondria, measured as loss of absorbance at 540 nm.</br></br>Kidney cortex mitochondria in K⁺-based media are non-functional in [K⁺] ranging from 37-146 mM. Heart mitochondria do not display K+-sensitivity to the same degree, but rather increase respiratory function with increasing [K⁺]. Furthermore, we demonstrated that a tissue specific difference in mitochondria K⁺-channels may explain these differences. The present study therefore demonstrates the importance of choosing a correct ''in vitro media'' to ensure a high quality of mitochondria research.urthermore, we demonstrated that a tissue specific difference in mitochondria K⁺-channels may explain these differences. The present study therefore demonstrates the importance of choosing a correct ''in vitro media'' to ensure a high quality of mitochondria research.)
• Lyon 2006 Anal Chem  + (A method for low-level, low-potential elec … A method for low-level, low-potential electrochemical detection of hydrogen peroxide using a chemically activated redox mediator is presented. This method is unique in that it utilizes a mediator, Amplex Red, which is only redox-active when chemically oxidized by H2O2 in the presence of the enzyme horseradish peroxidase (HRP). When employed in concert with microelectrode square wave voltammetry to optimize sensing at ultralow concentrations (<1 microM), this method exhibits marked improvements in analytical sensitivity and detection limits (limit of detection as low as 8 pM) over existing protocols. Sensing schemes incorporating both freely diffusing and immobilized HRP are evaluated, and the resulting analytical sensitivities are 1.22 +/- 0.04 and (2.1 +/- 0.6) x 10(-1) microA/(microM mm2), respectively, for peroxide concentrations in the high picomolar to low micromolar range. A second linear region exists for lower peroxide concentrations. Furthermore, quantitative enzyme kinetics analysis using Michaelis-Menten parameters is possible through interpretation of data collected in this scheme. Km values for soluble and immobilized HRP were 84 +/- 13 and 504 +/- 19 microM, respectively. This method is amenable to any biological detection scheme that generates hydrogen peroxide as a reactive product.ates hydrogen peroxide as a reactive product.)
• Cheng 2017 US Patent  + (A method for treating a microbial infection in a subject includes administering to the subject a pharmaceutical composition which has a therapeutically effective amount of an antimicrobial peptide containing a derivative of P-113.)
• Lee 2010 Curr Biol  + (A mild inhibition of mitochondrial respira … A mild inhibition of mitochondrial respiration extends the life span of many organisms, including yeast, worms, flies, and mice, but the underlying mechanism is unknown. One environmental condition that reduces rates of respiration is hypoxia (low oxygen). Thus, it is possible that mechanisms that sense oxygen play a role in the longevity response to reduced respiration. The hypoxia-inducible factor HIF-1 is a highly conserved transcription factor that activates genes that promote survival during hypoxia. In this study, we show that inhibition of respiration in C. elegans can promote longevity by activating HIF-1. Through genome-wide screening, we found that RNA interference (RNAi) knockdown of many genes encoding respiratory-chain components induced hif-1-dependent transcription. Moreover, HIF-1 was required for the extended life spans of clk-1 and isp-1 mutants, which have reduced rates of respiration. Inhibiting respiration appears to activate HIF-1 by elevating the level of reactive oxygen species (ROS). We found that ROS are increased in respiration mutants and that mild increases in ROS can stimulate HIF-1 to activate gene expression and promote longevity. In this way, HIF-1 appears to link respiratory stress in the mitochondria to a nuclear transcriptional response that promotes longevity.iptional response that promotes longevity.)
• Zelenka 2015 Oxid Med Cell Longev  + (A moderate elevation of reactive oxygen sp … A moderate elevation of reactive oxygen species (ROS) production and a mild inhibition of mitochondrial respiratory chain have been associated with a health promotion and a lifespan extension in several animal models of aging. Here, we tested whether this phenomenon called mitohormesis could be mediated by L-lactate. The treatment with 5 mM L-lactate significantly increased H₂O₂ production and slightly inhibited the respiration in cultured skin fibroblasts and in isolated mitochondria. The L-lactate exposure was associated with oxidation of intracellular glutathione, phosphorylation of 5'AMP-activated protein kinase (AMPK), and induction of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC1α) transcription. A replicative aging of fibroblasts (L0) with a constant (LC), or intermittent 5 mM L-lactate (LI) in media showed that the high-passage LI fibroblasts have higher respiration, lower H₂O₂ release, and lower secretion of L-lactate compared to L0 and LC. This protection against mitochondrial dysfunction in LI cells was associated with lower activity of mechanistic target of rapamycin complex 1 (mTORC1), less signs of cellular senescence, and increased autophagy compared to L0 and LC. In conclusion, we demonstrated that intermittent but not constant exposure to L-lactate triggers mitohormesis, prevents aging-associated mitochondrial dysfunction, and improves other markers of aging. prevents aging-associated mitochondrial dysfunction, and improves other markers of aging.)
• Lee 2019 Nat Metab  + (A moderate reduction of body temperature c … A moderate reduction of body temperature can induce a remarkable lifespan extension. Here we examine the link between cold temperature, germ line fitness and organismal longevity. We show that low temperature reduces age-associated exhaustion of germ stem cells (GSCs) in ''Caenorhabditis elegans'', a process modulated by thermosensory neurons. Notably, robust self-renewal of adult GSCs delays reproductive aging and is required for extended lifespan at cold temperatures. These cells release prostaglandin E2 (PGE2) to induce cbs-1 expression in the intestine, increasing somatic production of hydrogen sulfide (H2S), a gaseous signaling molecule that prolongs lifespan. Whereas loss of adult GSCs reduces intestinal cbs-1 expression and cold-induced longevity, application of exogenous PGE2 rescues these phenotypes. Importantly, tissue-specific intestinal overexpression of cbs-1 mimics cold-temperature conditions and extends longevity even at warm temperatures. Thus, our results indicate that GSCs communicate with somatic tissues to coordinate extended reproductive capacity with longevity.nded reproductive capacity with longevity.)
• Heidler 2013 Abstract MiP2013  + (A morphological hallmark of the failing hu … A morphological hallmark of the failing human heart is a devastative autophagic degradation of cellular structures starting from the perinuclear region, proposed to actively shift the heart into a decompensated state [1]. We studied heart samples from different species, i.e. a mouse model of cardiac specific expression of MCP1 that autonomously develops heart failure [2], hibernating Syrian hamsters [3] and a pig model of mitochondrial dysfunction exposed to hyperbaric oxygen.</br></br>Our data reveal an age-dependent increase of perinuclear degradation in mouse hearts that occurred prior to the onset of cardiac dysfunction. These center core-like lesions in the myofibrillar compartment are most likely the end-stage result of a vicious cycle that starts with a physiological response to lowered levels of cardiac workload. Accordingly we found that in hibernating Syrian hamsters under conditions of depressed metabolism interfibrillar mitochondria are reversibly silenced whilst subsarcolemmal mitochondria remain more active. Central remodeling of cardiomyocyte compartments is a phenomenon primarily known in the hibernating myocardium [4]. Here we show in pig hearts that the isolated impairment of the interfibrillary compartment can be fully re-activated upon treatment with hyperbaric oxygen.</br></br>We conclude that differential compartment regulation by switching the activity status of mitochondrial sub-populations from on to off and vice versa might provide a hitherto unnoticed flexible on-demand plasticity in cardiomyocytes. Such alterations make proper myofibril contraction in the silenced compartment unlikely. Silenced mitochondria can be re-activated on demand. Only long-lasting mitochondrial silencing, e.g. upon chronic cardiac overload, might increase the risk of adverse cardiomyocyte remodeling. risk of adverse cardiomyocyte remodeling.)
• Canton 1995 Biochem J  + (A new criterion is utilized for the interp … A new criterion is utilized for the interpretation of flow-force relationships in rat liver mitochondria. The criterion is based on the view that the nature of the relationship between the H+/O ratio and the membrane potential can be inferred from the relationship between ohmic-uncoupler-induced extra respiration and the membrane potential. Thus a linear relationship between extra respiration and membrane potential indicates unequivocally the independence of the H+/O ratio from the membrane potential and the leak nature of the resting respiration [Brand, Chien, and Diolez (1994) Biochem. J. 297, 27-29]. On the other hand, a non-linear relationship indicates that the H+/O ratio is dependent on the membrane potential. The experimental assessment of this relationship in the presence of an additional ohmic leak, however, is rendered difficult by both the uncoupler-induced depression of membrane potential and the limited range of dependence of the H+/O ratio on the membrane potential. We have selected conditions, i.e. incubation of mitochondria at low temperatures, where the extent of non-linearity is markedly increased. It appears that the nature of the resting respiration of mitochondria in vitro is markedly dependent on the temperature: at low temperatures the percentage of resting respiration due to membrane leak decreases and that due to intrinsic uncoupling of the proton pumps increases. uncoupling of the proton pumps increases.)
• Chinopoulos 2009  + (A novel method exploiting the differential … A novel method exploiting the differential affinity of ADP and ATP to Mg(2+) was developed to measure mitochondrial ADP-ATP exchange rate. The rate of ATP appearing in the medium after addition of ADP to energized mitochondria, is calculated from the measured rate of change in free extramitochondrial [Mg²⁺] reported by the membrane-impermeable 5K⁺ salt of the Mg²⁺-sensitive fluorescent indicator, Magnesium Green, using standard binding equations. The assay is designed such that the adenine nucleotide translocase (ANT) is the sole mediator of changes in [Mg²⁺] in the extramitochondrial volume, as a result of ADP-ATP exchange. We also provide data on the dependence of ATP efflux rate within the 6.8-7.8 matrix pH range as a function of membrane potential. Finally, by comparing the ATP-ADP steady-state exchange rate to the amount of the ANT in rat brain synaptic, brain nonsynaptic, heart and liver mitochondria, we provide molecular turnover numbers for the known ANT isotypes. and liver mitochondria, we provide molecular turnover numbers for the known ANT isotypes.)
• Sjoevall 2015 US Patent  + (A novel method useful in drug screening. T … A novel method useful in drug screening. The method is useful for testing effects of substances on the mitochondria, notably toxic or beneficial effects of drug substances or candidate drug substances. The method is based on measurement in live human mitochondria ''ex vivo'', but in a setting as near the ''in vivo'' situation as possible. The method is also useful for testing substances impact on the mitochondrial respiration. The method can be used to i) screening and selection of early or late stage drug candidates in cells derived from blood from healthy individuals or in so-called buffy coat, which is a concentrated solution of platelets and white blood cells, ii) testing a patient's sensitivity to a known mitochondrial toxicant, iii) analysing mitochondrial drug toxicity in clinical trials, and/or iv) analysing beneficial effects of drugs intended to improve mitochondrial function.ntended to improve mitochondrial function.)
• Farrar 2015 US Patent  + (A nucleic acid sequence encoding the yeast … A nucleic acid sequence encoding the yeast NDI1 protein of SEQ ID NO: 542 or a functional variant thereof having at least 90% sequence identity with SEQ ID NO: 2 is described. The nucleic acid sequence comprises at least 50 codons which are codon optimised compared with the sequence of yeast NDI1 gene of SEQ ID NO: 1. An immune optimised functional variant of the yeast NDI1 protein of SEQ ID NO: 542 having at least 90% sequence identity with SEQ ID NO: 542 is also described, and includes at least one amino acid change selected from the group consisting of L194F, K283E, K9R, S142N, L501M, L402I, A386S, S85K, F89H, L93M, K195E, L18M, K213E, K372E, L258F, K510E, L158M, R478Q, L482M. K372E, L258F, K510E, L158M, R478Q, L482M.)
• Bentinger 2007 Mitochondrion  + (A number of functions for coenzyme Q (CoQ) … A number of functions for coenzyme Q (CoQ) have been established during the years but its role as an effective antioxidant of the cellular membranes remains of dominating interest. This compound is our only endogenously synthesized lipid soluble antioxidant, present in all membranes and exceeding both in amount and efficiency that of other antioxidants. The protective effect is extended to lipids, proteins and DNA mainly because of its close localization to the oxidative events and the effective regeneration by continuous reduction at all locations. Its biosynthesis is influenced by nuclear receptors which may give the possibility, in the future, by using agonists or antagonists, of reestablishing the normal level in deficiencies caused by genetic mutations, aging or cardiomyopathy. An increase in CoQ concentration in specific cellular compartments in the presence of various types of oxidative stress appears to be of considerable interest.ss appears to be of considerable interest.)
• Bastow 2016 J Cell Sci  + (A number of genes have been linked to fami … A number of genes have been linked to familial forms of the fatal motor neuron disease amyotrophic lateral sclerosis (ALS). Over 150 mutations within the gene encoding superoxide dismutase 1 (SOD1) have been implicated in ALS, but why such mutations lead to ALS-associated cellular dysfunction is unclear. In this study, we identify how ALS-linked SOD1 mutations lead to changes in the cellular health of the yeast ''Saccharomyces cerevisiae''. We find that it is not the accumulation of aggregates but the loss of Sod1 protein stability that drives cellular dysfunction. The toxic effect of Sod1 instability does not correlate with a loss of mitochondrial function or increased production of reactive oxygen species, but instead prevents acidification of the vacuole, perturbs metabolic regulation and promotes senescence. Central to the toxic gain-of-function seen with the SOD1 mutants examined was an inability to regulate amino acid biosynthesis. We also report that leucine supplementation results in an improvement in motor function in a ''Caenorhabditis elegans'' model of ALS. Our data suggest that metabolic dysfunction plays an important role in Sod1-mediated toxicity in both the yeast and worm models of ALS.</br></br>© 2016. Published by The Company of Biologists Ltd.ublished by The Company of Biologists Ltd.)
• Ruiz-Pesini 2004 Science  + (A phylogenetic analysis of 1125 global hum … A phylogenetic analysis of 1125 global human mitochondrial DNA (mtDNA) sequences permitted positioning of all nucleotide substitutions according to their order of occurrence. The relative frequency and amino acid conservation of internal branch replacement mutations was found to increase from tropical Africa to temperate Europe and arctic northeastern Siberia. Particularly highly conserved amino acid substitutions were found at the roots of multiple mtDNA lineages from higher latitudes. These same lineages correlate with increased propensity for energy deficiency diseases as well as longevity. Thus, specific mtDNA replacement mutations permitted our ancestors to adapt to more northern climates, and these same variants are influencing our health today.variants are influencing our health today.)
• Berg 2016 Science  + (A preprint is a complete scientific manusc … A preprint is a complete scientific manuscript (often one also being submitted to a peer-reviewed journal) that is uploaded by the authors to a public server without formal review. After a brief inspection to ensure that the work is scientific in nature, the posted scientific manuscript can be viewed without charge on the Web.</br></br>Conclusions: Preprints could play important roles in accelerating scientific progress; they could serve the needs and foster the careers of scientists; and, in cooperation with existing journals, they could enhance the current system for communicating results and ideas in the life sciences. However, preprints are relatively new to biology, and many questions remain unanswered. Will funding agencies encourage the use of preprint servers? Will all journals accept manuscripts for publication after they have been disseminated as preprints? Will the life sciences community find ways to make biology preprints easily discoverable? And will researchers themselves decide to submit, cite, and evaluate work presented in preprint form? The cooperative spirit displayed by the attendees at ASAPbio gives hope that these complex issues, as well as others that limit the communication of scientific ideas and results, can be addressed in a productive and thoughtful manner.sed in a productive and thoughtful manner.)
• Committee 2018 COPE Discussion Document  + (A preprint is a scholarly manuscript poste … A preprint is a scholarly manuscript posted by the author(s) in an openly accessible platform, usually before or in parallel with the peer review process. While the sharing of manuscripts via preprint platforms has been common in some disciplines (such as physics and mathematics) for many years, uptake in other disciplines traditionally had been low, possibly influenced by differences in research culture and strong opposition by some journal publishers [1]. The landscape has evolved rapidly in other fields in recent years, however, thanks to the launch of additional, discipline-specific preprint platforms and increased support by funders and initiatives such as ASAPBio[2, 3].ers and initiatives such as ASAPBio[2, 3].)
• Gnaiger 1991 Soc Exp Biol Seminar Series  + (A previous critique of the term facultative invertebrate anaerobiosis focused on the duration of anoxia. An addition, important, yet much neglected aspect is dicussed here, namely the extent and quantification of the 'anaerobic' condition.)
• Podrabsky 2000 Am J Physiol Regul Integr Comp Physiol  + (A previous phylogenetic analysis among 15 … A previous phylogenetic analysis among 15 taxa of the teleost fish ''Fundulus'' suggested that there should be thermal-adaptive differences in heart metabolism among populations. To test this hypothesis, the rate of oxygen consumption and the activities of all 11 glycolytic enzymes were measured in isolated heart ventricle from two populations of ''Fundulus heteroclitus''. Heart ventricular metabolism is greater in a northern population versus a southern population of these fish. Analysis of the amount of glycolytic enzymes indicates that 87% of the variation in cardiac metabolism within and between populations is explained by the variation in three enzymes (pyruvate kinase, glyceraldehyde-3-phosphate dehydrogenase, and lactate dehydrogenase). These enzymes are the same three enzymes that were predicted to be important based on previously determined phylogenetic patterns of expression. Our data indicate that near-equilibrium enzymes, as well as classically defined rate-limiting enzymes, can also influence metabolism.ng enzymes, can also influence metabolism.)
• Gurakan 1990 Thermochim Acta  + (A procedure has been developed for the pre … A procedure has been developed for the preparation of microbial biomass of standard, defined quality suitable for the determination of elemental composition and enthalpy of combustion. Furthermore methods for the determination of residual moisture and ash content of biomass samples have been established. The results indicate that samples should be prepared in a freeze-dried (lyophilized) state and that residual moisture content should be determined immediately prior to sample preparation for combustion calorimetry and elemental analysis. Results from such analysis should then be related to material which is first freeze- dried and subsequently oven dried (100 °C for 24 hours) as reference state. The method outlined here for microbial biomass should prove suitable for biological samples from a wide variety of sources including both pure proteins, fats etc. as well as cells and tissues.s, fats etc. as well as cells and tissues.)
• Bradford 1976 Anal Biochem  + (A protein determination method which invol … A protein determination method which involves the binding of Coomassie Brilliant Blue G-250 to protein is described. The binding of the dye to protein causes a shift in the absorption maximum of the dye from 465 to 595 nm, and it is the increase in absorption at 595 nm which is monitored. This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr. There is little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose. A small amount of color is developed in the presence of strongly alkaline buffering agents, but the assay may be run accurately by the use of proper buffer controls. The only components found to give excessive interfering color in the assay are relatively large amounts of detergents such as sodium dodecyl sulfate, Triton X-100, and commercial glassware detergents. Interference by small amounts of detergent may be eliminated by the use of proper controls. eliminated by the use of proper controls.)
• Lam 1967 Arch Biochem Biophys  + (A protein factor, designated as Factor B, … A protein factor, designated as Factor B, was extracted from lyophilized acetone-washed bovine heart mitochondria and purified by ammonium sulfate fractionation, and ion-exchange chromatography on DEAE-cellulose and CM-cellulose. Centrifugation in a sucrose density gradient showed that the activity of the purified factor was closely associated with a symmetrical protein peak comprising approximately 70% of the protein. Its molecular weight was estimated to be 32,000, using hemoglobin and cytochrome c as markers. Factor B produces several-fold stimulation of ATP-driven NAD reduction, and of net phosphorylation coupled to NADH or succinate oxidation in ammonia particles. The stimulation of ATP-driven NAD reduction activity exceeds that given by an optimal amount of oligomycin, and in the presence of a saturation level of Factor B, oligomycin stimulation disappears. Also, Factor B stimulation is evident in urea-depleted particles which have been supplemented by Factor A. These particles show no stimulation by oligomycin. The results suggest that Factor B may participate in the energy transfer reactions between the respiratory chain and the terminal step resulting in ATP synthesis. terminal step resulting in ATP synthesis.)
• Wijermars 2016 Am J Transplant  + (A recent seminal paper implicated ischemia … A recent seminal paper implicated ischemia-related succinate accumulation followed by succinate driven-reactive oxygen species formation as key driver of ischemia reperfusion injury. Although the data show that the mechanism is universal for all organs tested (kidney, liver, heart and brain), a remaining question is to what extend these observations for mouse translate to man. We here show that succinate accumulation is not a universal event during ischemia, and does not occur during renal graft procurement, in fact tissue succinate content progressively decreases with advancing graft ischemia time (p<0.007). Contrasting responses were also found with respect to mitochondrial susceptibility towards ischemia and reperfusion, with rodent mitochondria robustly resistant towards warm ischemia, but human and pig mitochondria being highly susceptible to warm ischemia (p<0.05). These observations suggest that succinate-driven reactive oxygen formation does not occur in the context of kidney transplantation. In fact absent allantoin release from the reperfused grafts suggests minimal oxidative stress during clinical reperfusion.</br></br>This article is protected by copyright. All rights reserved. is protected by copyright. All rights reserved.)
• 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].</br></br></br>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. </br></br></br>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? </br></br></br>Contribution to K-Regio ''[[MitoCom_O2k-Fluorometer|MitoCom Tyrol]]''.</br></br>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.]]</br></br>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]]</br></br>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].</br></br>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. </br>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]. </br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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:</br>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.</br></br>METHODS:</br>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.</br></br>RESULTS:</br>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).</br></br>CONCLUSION:</br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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).</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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).</br></br>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: </br>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.</br>METHODS: </br>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.</br>RESULTS: </br>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.</br>CONCLUSIONS/INTERPRETATION:</br>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: </br>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.</br></br>METHODS: </br>Mitochondrial oxygen consumption, glomerular filtration rate and proteinuria were investigated in db/db mice and corresponding controls with and without coenzyme Q10 (CoQ10) treatment.</br></br>RESULTS: </br>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).</br></br>CONCLUSIONS/INTERPRETATION: </br>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.</br></br>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. </br></br>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.</br></br>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: </br></br>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.</br></br>METHODS AND RESULTS:</br></br>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.</br></br>CONCLUSIONS:</br></br>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: </br></br>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.</br></br>RESULTS: </br></br>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 .</br></br>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.</br></br>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. </br></br>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.</br></br>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.</br></br>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.</br></br>RESULTS:</br>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.</br></br>INNOVATION:</br>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.</br></br>CONCLUSION:</br>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.</br> </br>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.</br> </br>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.</br></br>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 (VO_2max; 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.</br></br>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 VO_2max, 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 AMPK_γ3 subunit is predominantly expressed in skeletal muscle, mostly in type II glycolytic fiber types. We determined whether the AMPK_γ3 subunit has a role in signaling pathways that mediate mitochondrial biogenesis in skeletal muscle. We provide evidence that overexpression or ablation of the AMPK_γ3 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 AMPK_γ3 subunit (Tg-AMPK_γ3^225Q) 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-AMPK_γ3^225Q 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. </br></br>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).</br></br>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. </br></br>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].</br></br>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].</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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. </br></br>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.</br></br>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 (F₁F_o) 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 F₁F_o-reconstituted proteoliposomes and isolated mitochondria, we show F₁F_o 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 F₁F_o 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 F_o 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 F₁F_o 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 (F₁F_o) synthesizes daily our body’s weight in ATP, whose production-rate can be transiently increased several-fold. Using purified mammalian F₁F_o-reconstituted proteoliposomes and isolated mitochondria, we show that F₁F_o 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. F₁F_o 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 F₁F_o to operate as a primary mitochondrial K⁺-uniporter regulating energy supply-demand matching, and as the recruitable mitochondrial K_ATP-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 F₁F_o 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 F₁F_o 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.</br></br>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.</br></br>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.</br></br>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.</br></br><small>Copyright © 2018. Published by Elsevier Inc.</small>degeneration in the cortex under diabetic conditions. <small>Copyright © 2018. Published by Elsevier Inc.</small>)
• 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.<br>ing mitochondrial dynamics, suggesting drastic mitochondrial malfunctions.<br>)
• 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.</br></br>© 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. </br></br>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 diseases</br>accounted for 8.3% of natural deaths in South Africa during 2013,</br>ranking the 6th place as cause of mortality. With the efficiency</br>of therapies aimed at decreasing mortality from heart disease, life</br>expectancy increased. As result of this, the focus of recent research</br>changed towards understanding the energy demands of the heart in</br>order to optimize function. Because of its high energetic needs, the</br>human heart utilizes between 3.5 and 6 kg of ATP per day to function.</br>This is produced by its mitochondrial populations which occupy up to</br>50% of the volume of a cardiomyocyte. A close link therefore exists</br>between mitochondrial dysfunction and heart disease. In addition, there</br>is growing recognition that inborn errors of metabolism can influence</br>cardiomyocyte dysfunction [1] and that primary inherited mitochondrial</br>diseases display a full spectrum of cardiac disorders [2].</br>ATM is a 350kDa serine/threonine protein kinase displaying homologies</br>to the large protein family of PI3-Kinases, although it lacks the ability to</br>phosphorylate lipids [3]. It came under scrutiny because of the disease,</br>Ataxia-telangiectasie (A-T), which is an autosomal, recessive disorder</br>that progressively affects multiple organs. This disease is caused by</br>mutations in the Atm gene, resulting in lack or inactivation of the ATM</br>protein [4]. ATM in the cell can be localized to the nucleus, cytoplasm of</br>mitochondria.</br></br>We became interested in myocardial ATM because it was found that</br>skeletal muscle of insulin resistant, obese rats had dramatically reduced</br>levels of the so-called ATM protein, in association with the well-known</br>reduced activation of the insulin/ phosphatidylinositol 3 kinases (PI3-</br>kinase)/PKB/Akt pathway, which is the main mechanism of relaying the</br>metabolic effects of insulin [5]. Foster et al [6] found structural and functional changes in the hearts of ATM KO mice, using echocardiography and</br>Doppler echocardiography.</br></br>The mitochondrial association of ATM protein kinase plays an important</br>role in its integrity and functioning such that ATM deficiency results in</br>defects in mitochondrial respiration [7]. ATM also regulates mitochondrial</br>biogenesis and DNA content [8]. In addition, it was demonstrated that a</br>mitochondria-targeted antioxidant MitoQ, could decrease the features of</br>the metabolic syndrome in ATM+/-ApoE-/- mice [9]. This may be because</br>one of the mechanisms known to activate the ATM protein is increased</br>oxidative stress. Activated ATM initiates an anti-oxidant response based</br>on a metabolic shift while, in fibroblast cell lines, inactivation of ATM</br>is associated with increased ROS levels followed by expression and</br>activation 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. </br></br>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. </br></br>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.</br></br>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.</br></br>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.</br></br>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).</br></br>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-Lep^pre) 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-Lep^pre 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.</br></br>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.</br></br>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.</br></br>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.</br></br><small>Copyright © 2019 Elsevier Ltd. All rights reserved.</small> 2019 Elsevier Ltd. All rights reserved.</small>)
• 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.</br>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.</br></br>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. </br></br>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. </br></br>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''.</br></br>The aim of our work was to compare hepatotoxicity of APAP in rat and mouse hepatocytes in primary cultures.</br></br>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).</br></br>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.</br></br>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].</br> </br>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. </br>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.</br></br><small>© 2019 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).</small>(former Nordic Pharmacological Society).</small>)
• 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.</br></br>Respiration of intact or permeabilized rat pancreatic acini was studied at 37 °C using a Clark oxygen electrode.</br></br>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.</br></br>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⁺(K_ATP) 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 K_ATP 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 K_ATP 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 K_ATP channel blocker to inhibit diazoxide-induced flavoprotein fluorescence, commonly used as an assay of K_ATP channel activity. Indeed, consistent with our hypothesis, we found that decanoate inhibited diazoxide-induced flavoprotein oxidation. Taken together, our data question the “mitochondrial K_ATP 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 K_ATP 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 K_ATP 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+</sup> 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.</br></br>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.</br></br>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.</br></br>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.</br></br>© 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. </br></br>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.</br></br>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).</br></br>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. </br></br>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. </br></br>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.</br></br><small>Copyright © 2019 Elsevier Inc. All rights reserved.</small> 2019 Elsevier Inc. All rights reserved.</small>)
• 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</sub>] 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.</br></br>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.</br></br>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. </br></br>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 failure</br>was 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.</br></br>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 predominantly</br>apoptotic 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.</br></br>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.</br></br>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.</br></br>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.</br></br><small>Copyright © 2019 Elsevier Inc. All rights reserved.</small> 2019 Elsevier Inc. All rights reserved.</small>)
• 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, several</br>biological parameters were measured under or without MTX treatment in a panel of 13 ALL</br>cell lines. Proliferation tests, metabolic studies, drug synergism, quantification of cellular</br>respiration and the production of reactive oxygen species (ROS) were performed, as well as</br>the measurement of the activation of the NF-κB signaling pathway. Resistance of the MTX</br>strains within 48 h of treatment (but not 96 h) was related to the proliferation rate of the cells.</br>Treatment with MTX altered the concentration of 28 intracellular metabolites, highlights for a</br>consistent increase in glycine concentration. Intracellular concentrations of asparagine,</br>guanosine and glutathione – including the expression of genes from glutathione pathway –</br>were associated with MTX resistance. Supplementation of the culture medium with Nacetylcysteine,</br>a precursor metabolite of glutathione, promoted proliferation and resistance to</br>MTX; however, cell treatment with piperlongumine or hydrogen peroxide, two glutathione</br>scavengers and ROS promoters, did not potentiate the effect of MTX. MTX induced ROS in</br>ALL after 6 h of treatment with low fold change, though. Paradoxically, higher ROS</br>production was found in cell lines with high MTX resistance and intracellular glutathione.</br>The oxygen uptake of the cell lines was not associated with MTX resistance and a preliminary</br>test showed that MTX did not alter cellular respiration. MTX activated the transcription factor</br>NF-κB in some ALL cell lines and, interestingly, the activation of this transcription factor by</br>tumor necrosis factor alpha (TNF-α) was positively correlated with the resistance of leukemic</br>lines to MTX. A wide bibliographic review allowed both the integration of the obtained</br>results to the most current knowledge on the subject, and the identification of new paths to be</br>explored 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.</br></br>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.</br></br>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.</br></br>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).</br></br>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.</br></br>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.</br></br><small>© 2020 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.</small>ular Medicine and John Wiley & Sons Ltd.</small>)
• 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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>This study investigates on acute hypoxia and normoxia impact on cardiac and brain mitochondrial bioenergetics and the possible occurrence of different gender responses.</br></br>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.</br></br>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.</br></br>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.</br></br>Among female heart mitochondria, SSM only showed a decrease in state 3 of complex II after acute hypoxia.</br></br>In conclusion, in both genders cardiac and brain mitochondrial bioenergetics change after athletic training in acute hypoxia.</br></br>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.</br></br>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.</br><small></br># 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</br># 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</br># 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</br># 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.1318547111</br></small>https://doi.org/10.1073/pnas.1318547111 </small>)
• 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.</br></br><small>Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.</small>ished by Elsevier Inc. All rights reserved.</small>)
• 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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br></br>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.</br><small></br># Dambrova M et al (2022) Acylcarnitines: nomenclature, biomarkers, therapeutic potential, drug targets and clinical trials. Pharmacol Rev 74:1-50 (in press).</br></small>ials. Pharmacol Rev 74:1-50 (in press). </small>)
• 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 matrix</br>are a major source of ATP after oxidation. Their oxidation process,</br>termed β-oxidation, runs through four sequential enzymes namely:</br>acyl-CoA dehydrogenase, 2-enoyl-CoA hydratase, L-3-hydroxyacyl-</br>CoA dehydrogenase, and 3-ketoacyl-CoA thiolase [1]. Acyl-CoA</br>dehydrogenases transfer single electrons to electron transferring</br>flavoprotein (ETF) [2] which donates electrons directly to the ubiquinone</br>(Q) pool in the mitochondrial inner membrane. Hydroxyacyl-CoA</br>dehydrogenase transfers electrons to NAD+ and the reduced NADH</br>is oxidized by complex I. The end product of β-oxidation, acetyl-CoA,</br>condenses with oxaloacetate to form citrate which is oxidized by the</br>Krebs cycle. Oxidation of fatty acylcarnitines therefore contributes to</br>OXPHOS and ATP production by donating electrons at various points of</br>the electron transfer-pathway.</br></br>To assess oxidation of acylcarnitines under various experimental</br>conditions, scientist often measure oxygen consumption in isolated</br>mitochondria, permeabilized cells, or tissues in an oxygraph using</br>a variety of substrate combinations including palmatoylcarnitine in</br>combination with carnitine or malate. Use of palmatoylcarnitine alone</br>yields low oxygen flux rates and is not responsive to ADP, oligomycin</br>or uncouplers. These observations are attributed to a low CoA/</br>palmatoylCoA ratio which inactivates 3-ketoacyl-CoA thiolase and slows</br>down or stops β-oxidation. Use of palmatoylcarnitine in combination with</br>carnitine or malate increase State 2 respiration (oxygen consumption</br>with substrate without addition of ADP) and are responsive to ADP,</br>oligomycin and uncouples -- but to different degrees. The increase in</br>oxygen flux rates after ADP or uncoupler addition is explained by the</br>increased CoA/palmatoylCoA ratio which favours β-oxidation. The</br>differences in response to ADP and uncoupler is probably due the fact</br>that oxidation of palmitoylcarnitine in the presence of carnitine transfers</br>electrons to the ETS without involving the Krebs cycle whereas oxidation</br>of 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.</br></br>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.</br></br><small>Copyright © 2014 Elsevier Inc. All rights reserved.</small> 2014 Elsevier Inc. All rights reserved.</small>)
• 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<sub> … 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.</br></br>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.</br></br>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.</br></br>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. </br></br>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.</br></br>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).</br></br>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. </br>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).</br></br>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.</br></br>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.</br>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.</br></br>On November 1, 2017, the Board on Research Data and Information (BRDI) of the National Academies of</br>Sciences, Engineering, and Medicine organized a symposium to explore these issues. Invited experts from China, Europe, and the United States were asked to:</br>* Review proposed science data infrastructure projects around the globe;</br>* Highlight, compare, and contrast the plans and capabilities of these projects; and</br>* 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 (VO_2peak) as well as what role mitochondrial coupled and uncoupled respiration may play in whole body aerobic capacity and cycling economy.</br></br>Cycling net oxygen uptake and VO_2peak 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.</br></br>Pre (r=0.34, p<0.05) and post exercise training (r=0.62, p<0.01) VO_2peak 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 VO_2peak and changes in cycle net oxygen uptake persist after training, even after adjusting for changes in RQ (an index of fat oxidation).</br></br>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.</br></br>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.</br></br>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.</br></br>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).</br></br>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.)