1
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Holwerda AM, Dirks ML, Barbeau PA, Goessens J, Gijsen A, van Loon LJC, Holloway GP. Mitochondrial bioenergetics are not associated with myofibrillar protein synthesis rates. J Cachexia Sarcopenia Muscle 2024. [PMID: 39007407 DOI: 10.1002/jcsm.13532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 05/13/2024] [Accepted: 06/03/2024] [Indexed: 07/16/2024] Open
Abstract
BACKGROUND Mitochondria represent key organelles influencing cellular homeostasis and have been implicated in the signalling events regulating protein synthesis. METHODS We examined whether mitochondrial bioenergetics (oxidative phosphorylation and reactive oxygen species (H2O2) emission, ROS) measured in vitro in permeabilized muscle fibres represent regulatory factors for integrated daily muscle protein synthesis rates and skeletal muscle mass changes across the spectrum of physical activity, including free-living and bed-rest conditions: n = 19 healthy, young men (26 ± 4 years, 23.4 ± 3.3 kg/m2) and following 12 weeks of resistance-type exercise training: n = 10 healthy older men (70 ± 3 years, 25.2 ± 2.1 kg/m2). Additionally, we evaluated the direct relationship between attenuated mitochondrial ROS emission and integrated daily myofibrillar and sarcoplasmic protein synthesis rates in genetically modified mice (mitochondrial-targeted catalase, MCAT). RESULTS Neither oxidative phosphorylation nor H2O2 emission were associated with muscle protein synthesis rates in healthy young men under free-living conditions or following 1 week of bed rest (both P > 0.05). Greater increases in GSSG concentration were associated with greater skeletal muscle mass loss following bed rest (r = -0.49, P < 0.05). In older men, only submaximal mitochondrial oxidative phosphorylation (corrected for mitochondrial content) was positively associated with myofibrillar protein synthesis rates during exercise training (r = 0.72, P < 0.05). However, changes in oxidative phosphorylation and H2O2 emission were not associated with changes in skeletal muscle mass following training (both P > 0.05). Additionally, MCAT mice displayed no differences in myofibrillar (2.62 ± 0.22 vs. 2.75 ± 0.15%/day) and sarcoplasmic (3.68 ± 0.35 vs. 3.54 ± 0.35%/day) protein synthesis rates when compared with wild-type mice (both P > 0.05). CONCLUSIONS Mitochondrial oxidative phosphorylation and reactive oxygen emission do not seem to represent key factors regulating muscle protein synthesis or muscle mass regulation across the spectrum of physical activity.
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Affiliation(s)
- Andrew M Holwerda
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Marlou L Dirks
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
- Department of Public Health and Sport Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Pierre-Andre Barbeau
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Joy Goessens
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Annemie Gijsen
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Luc J C van Loon
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
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2
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Lin W, Zhou J, Ma Y, Ge L, Luo Y, Wang Y, Zhou S. Prognostic value of mitochondrial CKMT2 in Pan-cancer and its tumor immune correlation analysis. Sci Rep 2024; 14:342. [PMID: 38172162 PMCID: PMC10764887 DOI: 10.1038/s41598-023-46468-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 11/01/2023] [Indexed: 01/05/2024] Open
Abstract
Mitochondrial metabolism has been shown to play a key role in immune cell survival and function, but mitochondrial creatine kinase 2 (CKMT2) has been relatively little studied about tumor immunity. We aimed to explore the prognostic value of CKMT2 in 33 cancer types and investigate its potential immune function. We used a range of bioinformatics approaches to explore the potential carcinogenic role of CKMT2 in multiple cancers. CKMT2 was lowly expressed in 14 tumor tissues and highly expressed in 4 tumor tissues. Immunohistochemical assays showed overexpression of CKMT2 in colon cancer and rectal cancer. CKMT2 overexpression was positively correlated with the prognosis of lung adenocarcinoma and prostate cancer. CKMT2 overexpression is mainly enriched in the adaptive immune system and immune regulatory pathways of immunoglobulins. Seven cancers were positively correlated with low CKMT2 expression in tumor microenvironment analysis. Among the five cancers, low expression of CKMT2 resulted in better immunotherapy treatment outcomes. There was a strong correlation between CKMT2 and most immune-related genes in specific cancer types. CKMT2 plays an important role in tumorigenesis and cancer immunity and can be used as a prognostic biomarker and potential target for cancer immunotherapy.
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Affiliation(s)
- Wei Lin
- State Key Laboratory of Targeting Oncology, National Center for International Research of Bio-targeting Theranostics, Guangxi Key Laboratory of Bio-targeting Theranostics, Collaborative Innovation Center for Targeting Tumor Diagnosis and Therapy, Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Jiamin Zhou
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, China
| | - Yili Ma
- Department of Pathology, Affiliated Cancer Hospital of Guangxi Medical University, Nanning, China
| | - Liuxing Ge
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, China
| | - Yiling Luo
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, China
| | - Yaobin Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, China
| | - Sufang Zhou
- State Key Laboratory of Targeting Oncology, National Center for International Research of Bio-targeting Theranostics, Guangxi Key Laboratory of Bio-targeting Theranostics, Collaborative Innovation Center for Targeting Tumor Diagnosis and Therapy, Guangxi Medical University, Nanning, 530021, Guangxi, China.
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, China.
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3
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Smith JAB, Murach KA, Dyar KA, Zierath JR. Exercise metabolism and adaptation in skeletal muscle. Nat Rev Mol Cell Biol 2023; 24:607-632. [PMID: 37225892 PMCID: PMC10527431 DOI: 10.1038/s41580-023-00606-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/30/2023] [Indexed: 05/26/2023]
Abstract
Viewing metabolism through the lens of exercise biology has proven an accessible and practical strategy to gain new insights into local and systemic metabolic regulation. Recent methodological developments have advanced understanding of the central role of skeletal muscle in many exercise-associated health benefits and have uncovered the molecular underpinnings driving adaptive responses to training regimens. In this Review, we provide a contemporary view of the metabolic flexibility and functional plasticity of skeletal muscle in response to exercise. First, we provide background on the macrostructure and ultrastructure of skeletal muscle fibres, highlighting the current understanding of sarcomeric networks and mitochondrial subpopulations. Next, we discuss acute exercise skeletal muscle metabolism and the signalling, transcriptional and epigenetic regulation of adaptations to exercise training. We address knowledge gaps throughout and propose future directions for the field. This Review contextualizes recent research of skeletal muscle exercise metabolism, framing further advances and translation into practice.
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Affiliation(s)
- Jonathon A B Smith
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Kevin A Murach
- Molecular Mass Regulation Laboratory, Exercise Science Research Center, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, AR, USA
| | - Kenneth A Dyar
- Metabolic Physiology, Institute for Diabetes and Cancer, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Juleen R Zierath
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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4
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Decker ST, Alexandrou-Majaj N, Layec G. Effects of acute cigarette smoke concentrate exposure on mitochondrial energy transfer in fast- and slow-twitch skeletal muscle. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148973. [PMID: 36972770 DOI: 10.1016/j.bbabio.2023.148973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/26/2023] [Accepted: 03/21/2023] [Indexed: 03/29/2023]
Abstract
The mechanisms underlying cigarette smoke-induced mitochondrial dysfunction in skeletal muscle are still poorly understood. Accordingly, this study aimed to examine the effects of cigarette smoke on mitochondrial energy transfer in permeabilized muscle fibers from skeletal muscles with differing metabolic characteristics. The electron transport chain (ETC) capacity, ADP transport, and respiratory control by ADP were assessed in fast- and slow-twitch muscle fibers from C57BL/6 mice (n = 11) acutely exposed to cigarette smoke concentrate (CSC) using high-resolution respirometry. CSC decreased complex I-driven respiration in the white gastrocnemius (CONTROL:45.4 ± 11.2 pmolO2.s-1.mg-1 and CSC:27.5 ± 12.0 pmolO2.s-1.mg-1; p = 0.01) and soleus (CONTROL:63.0 ± 23.8 pmolO2.s-1.mg-1 and CSC:44.6 ± 11.1 pmolO2.s-1.mg-1; p = 0.04). In contrast, the effect of CSC on Complex II-linked respiration increased its relative contribution to muscle respiratory capacity in the white gastrocnemius muscle. The maximal respiratory activity of the ETC was significantly inhibited by CSC in both muscles. Furthermore, the respiration rate dependent on the ADP/ATP transport across the mitochondrial membrane was significantly impaired by CSC in the white gastrocnemius (CONTROL:-70 ± 18 %; CSC:-28 ± 10 %; p < 0.001), but not the soleus (CONTROL:47 ± 16 %; CSC:31 ± 7 %; p = 0.08). CSC also significantly impaired mitochondrial thermodynamic coupling in both muscles. Our findings underscore that acute CSC exposure directly inhibits oxidative phosphorylation in permeabilized muscle fibers. This effect was mediated by significant perturbations of the electron transfer in the respiratory complexes, especially at complex I, in both fast and slow twitch muscles. In contrast, CSC-induced inhibition of the exchange of ADP/ATP across the mitochondrial membrane was fiber-type specific, with a large effect on fast-twitch muscles.
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Affiliation(s)
- Stephen T Decker
- Department of Kinesiology, University of Massachusetts Amherst, USA
| | | | - Gwenael Layec
- Department of Kinesiology, University of Massachusetts Amherst, USA; Institute for Applied Life Science, University of Massachusetts Amherst, USA.
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5
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Iannetta D, Inglis EC, Maturana FM, Spigolon G, Pogliaghi S, Murias JM. Transient speeding of V̇O2 kinetics following acute sessions of sprint interval training: Similar exercise dose but different outcomes in older and young adults. Exp Gerontol 2022; 164:111826. [DOI: 10.1016/j.exger.2022.111826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/10/2022] [Accepted: 04/26/2022] [Indexed: 11/30/2022]
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6
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A theoretical argument to support the biological benefits for insulin stimulating mitochondrial oxidative phosphorylation. CURRENT OPINION IN PHYSIOLOGY 2022. [DOI: 10.1016/j.cophys.2022.100491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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Newsom SA, Stierwalt HD, Ehrlicher SE, Robinson MM. Substrate-Specific Respiration of Isolated Skeletal Muscle Mitochondria after 1 h of Moderate Cycling in Sedentary Adults. Med Sci Sports Exerc 2021; 53:1375-1384. [PMID: 34127633 PMCID: PMC8206519 DOI: 10.1249/mss.0000000000002615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Skeletal muscle mitochondria have dynamic shifts in oxidative metabolism to meet energy demands of aerobic exercise. Specific complexes oxidize lipid and nonlipid substrates. It is unclear if aerobic exercise stimulates intrinsic oxidative metabolism of mitochondria or varies between substrates. METHODS We studied mitochondrial metabolism in sedentary male and female adults (n = 11F/4M) who were free of major medical conditions with mean ± SD age of 28 ± 7 yr, peak aerobic capacity of 2.0 ± 0.4 L·min-1, and body mass index of 22.2 ± 2 kg·m-2. Biopsies were collected from the vastus lateralis muscle on separate study days at rest or 15 min after exercise (1 h cycling at 65% peak aerobic capacity). Isolated mitochondria were analyzed using high-resolution respirometry of separate titration protocols for lipid (palmitoylcarnitine, F-linked) and nonlipid substrates (glutamate-malate, N-linked; succinate S-linked). Titration protocols distinguished between oxidative phosphorylation and leak respiration and included the measurement of reactive oxygen species emission (H2O2). Western blotting determined the protein abundance of electron transfer flavoprotein (ETF) subunits, including inhibitory methylation site on ETF-β. RESULTS Aerobic exercise induced modest increases in mitochondrial respiration because of increased coupled respiration across F-linked (+13%, P = 0.08), N(S)-linked (+14%, P = 0.09), and N-linked substrates (+17%, P = 0.08). Prior exercise did not change P:O ratio. Electron leak to H2O2 increased 6% increased after exercise (P = 0.06) for lipid substrates but not for nonlipid. The protein abundance of ETF-α or ETF-β subunit or inhibitory methylation on ETF-β was not different between rest and after exercise. CONCLUSION In sedentary adults, the single bout of moderate-intensity cycling induced modest increases for intrinsic mitochondrial oxidative phosphorylation that was consistent across multiple substrates.
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Affiliation(s)
- Sean A Newsom
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, OR
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8
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Insulin rapidly increases skeletal muscle mitochondrial ADP sensitivity in the absence of a high lipid environment. Biochem J 2021; 478:2539-2553. [PMID: 34129667 DOI: 10.1042/bcj20210264] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/07/2021] [Accepted: 06/14/2021] [Indexed: 11/17/2022]
Abstract
Reductions in mitochondrial function have been proposed to cause insulin resistance, however the possibility that impairments in insulin signaling negatively affects mitochondrial bioenergetics has received little attention. Therefore, we tested the hypothesis that insulin could rapidly improve mitochondrial ADP sensitivity, a key process linked to oxidative phosphorylation and redox balance, and if this phenomenon would be lost following high-fat diet (HFD)-induced insulin resistance. Insulin acutely (60 min post I.P.) increased submaximal (100-1000 µM ADP) mitochondrial respiration ∼2-fold without altering maximal (>1000 µM ADP) respiration, suggesting insulin rapidly improves mitochondrial bioenergetics. The consumption of HFD impaired submaximal ADP-supported respiration ∼50%, however, despite the induction of insulin resistance, the ability of acute insulin to stimulate ADP sensitivity and increase submaximal respiration persisted. While these data suggest that insulin mitigates HFD-induced impairments in mitochondrial bioenergetics, the presence of a high intracellular lipid environment reflective of an HFD (i.e. presence of palmitoyl-CoA) completely prevented the beneficial effects of insulin. Altogether, these data show that while insulin rapidly stimulates mitochondrial bioenergetics through an improvement in ADP sensitivity, this phenomenon is possibly lost following HFD due to the presence of intracellular lipids.
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9
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Malgoyre A, Prola A, Meunier A, Chapot R, Serrurier B, Koulmann N, Bigard X, Sanchez H. Endurance Is Improved in Female Rats After Living High-Training High Despite Alterations in Skeletal Muscle. Front Sports Act Living 2021; 3:663857. [PMID: 34124658 PMCID: PMC8193088 DOI: 10.3389/fspor.2021.663857] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 04/12/2021] [Indexed: 11/29/2022] Open
Abstract
Altitude camps are used during the preparation of endurance athletes to improve performance based on the stimulation of erythropoiesis by living at high altitude. In addition to such whole-body adaptations, studies have suggested that high-altitude training increases mitochondrial mass, but this has been challenged by later studies. Here, we hypothesized that living and training at high altitude (LHTH) improves mitochondrial efficiency and/or substrate utilization. Female rats were exposed and trained in hypoxia (simulated 3,200 m) for 5 weeks (LHTH) and compared to sedentary rats living in hypoxia (LH) or normoxia (LL) or those that trained in normoxia (LLTL). Maximal aerobic velocity (MAV) improved with training, independently of hypoxia, whereas the time to exhaustion, performed at 65% of MAV, increased both with training (P = 0.009) and hypoxia (P = 0.015), with an additive effect of the two conditions. The distance run was 7.98 ± 0.57 km in LHTH vs. 6.94 ± 0.51 in LLTL (+15%, ns). The hematocrit increased >20% with hypoxia (P < 0.001). The increases in mitochondrial mass and maximal oxidative capacity with endurance training were blunted by combination with hypoxia (−30% for citrate synthase, P < 0.01, and −23% for Vmax glut−succ, P < 0.001 between LHTH and LLTL). A similar reduction between the LHTH and LLTL groups was found for maximal respiration with pyruvate (−29%, P < 0.001), for acceptor-control ratio (−36%, hypoxia effect, P < 0.001), and for creatine kinase efficiency (−48%, P < 0.01). 3-hydroxyl acyl coenzyme A dehydrogenase was not altered by hypoxia, whereas maximal respiration with Palmitoyl-CoA specifically decreased. Overall, our results show that mitochondrial adaptations are not involved in the improvement of submaximal aerobic performance after LHTH, suggesting that the benefits of altitude camps in females relies essentially on other factors, such as the transitory elevation of hematocrit, and should be planned a few weeks before competition and not several months.
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Affiliation(s)
- Alexandra Malgoyre
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France.,Laboratoire de Biologie de l'Exercice pour la Performance et la Santé, Université Evry, Université Paris Saclay, Evry, France
| | - Alexandre Prola
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Adelie Meunier
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Rachel Chapot
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Bernard Serrurier
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Nathalie Koulmann
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France.,Laboratoire de Biologie de l'Exercice pour la Performance et la Santé, Université Evry, Université Paris Saclay, Evry, France.,Ecole du Val de Grâce, Paris, France
| | - Xavier Bigard
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France.,Ecole du Val de Grâce, Paris, France
| | - Hervé Sanchez
- Département des Environnements Opérationnels, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
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10
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Park N, Marquez J, Garcia MVF, Shimizu I, Lee SR, Kim HK, Han J. Phosphorylation in Novel Mitochondrial Creatine Kinase Tyrosine Residues Render Cardioprotection against Hypoxia/Reoxygenation Injury. J Lipid Atheroscler 2021; 10:223-239. [PMID: 34095014 PMCID: PMC8159762 DOI: 10.12997/jla.2021.10.2.223] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 12/18/2020] [Accepted: 01/06/2021] [Indexed: 11/09/2022] Open
Abstract
Objective Ischemic cardiomyopathy (ICM) is the leading cause of heart failure. Proteomic and genomic studies have demonstrated ischemic preconditioning (IPC) can assert cardioprotection against ICM through mitochondrial function regulation. Considering IPC is conducted in a relatively brief period, regulation of protein expression also occurs very rapidly, highlighting the importance of protein function modulation by post-translational modifications. This study aimed to identify and analyze novel phosphorylated mitochondrial proteins that can be harnessed for therapeutic strategies for preventing ischemia/reperfusion (I/R) injury. Methods Sprague-Dawley rat hearts were used in an ex vivo Langendorff system to simulate normal perfusion, I/R, and IPC condition, after which the samples were prepared for phosphoproteomic analysis. Employing human cardiomyocyte AC16 cells, we investigated the cardioprotective role of CKMT2 through overexpression and how site-directed mutagenesis of putative CKMT2 phosphorylation sites (Y159A, Y255A, and Y368A) can affect cardioprotection by measuring CKMT2 protein activity, mitochondrial function and protein expression changes. Results The phosphoproteomic analysis revealed dephosphorylation of mitochondrial creatine kinase (CKMT2) during ischemia and I/R, while preserving its phosphorylated state during IPC. CKMT2 overexpression conferred cardioprotection against hypoxia/reoxygenation (H/R) by increasing cell viability and mitochondrial adenosine triphosphate level, preserving mitochondrial membrane potential, and reduced reactive oxygen species (ROS) generation, while phosphomutations, especially in Y368, nullified cardioprotection by significantly reducing cell viability and increasing ROS production during H/R. CKMT2 overexpression increased mitochondrial function by mediating the proliferator-activated receptor γ coactivator-1α/estrogen-related receptor-α pathway, and these effects were mostly inhibited by Y368A mutation. Conclusion These results suggest that regulation of quantitative expression and phosphorylation site Y368 of CKMT2 offers a unique mechanism in future ICM therapeutics.
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Affiliation(s)
- Nammi Park
- Cardiovascular and Metabolic Disease Center, Smart Marine Therapeutics Center, Inje University, Busan, Korea
| | - Jubert Marquez
- Cardiovascular and Metabolic Disease Center, Smart Marine Therapeutics Center, Inje University, Busan, Korea.,Department of Health Sciences and Technology, Graduate School of Inje University, Busan, Korea
| | - Maria Victoria Faith Garcia
- Cardiovascular and Metabolic Disease Center, Smart Marine Therapeutics Center, Inje University, Busan, Korea.,Department of Health Sciences and Technology, Graduate School of Inje University, Busan, Korea
| | - Ippei Shimizu
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Sung Ryul Lee
- Cardiovascular and Metabolic Disease Center, Smart Marine Therapeutics Center, Inje University, Busan, Korea
| | - Hyoung Kyu Kim
- Cardiovascular and Metabolic Disease Center, Smart Marine Therapeutics Center, Inje University, Busan, Korea.,Department of Health Sciences and Technology, Graduate School of Inje University, Busan, Korea.,Department of Physiology, College of Medicine, Inje University, Busan, Korea
| | - Jin Han
- Cardiovascular and Metabolic Disease Center, Smart Marine Therapeutics Center, Inje University, Busan, Korea.,Department of Health Sciences and Technology, Graduate School of Inje University, Busan, Korea.,Department of Physiology, College of Medicine, Inje University, Busan, Korea
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11
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Hargreaves M, Spriet LL. Skeletal muscle energy metabolism during exercise. Nat Metab 2020; 2:817-828. [PMID: 32747792 DOI: 10.1038/s42255-020-0251-4] [Citation(s) in RCA: 411] [Impact Index Per Article: 102.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 06/25/2020] [Indexed: 12/12/2022]
Abstract
The continual supply of ATP to the fundamental cellular processes that underpin skeletal muscle contraction during exercise is essential for sports performance in events lasting seconds to several hours. Because the muscle stores of ATP are small, metabolic pathways must be activated to maintain the required rates of ATP resynthesis. These pathways include phosphocreatine and muscle glycogen breakdown, thus enabling substrate-level phosphorylation ('anaerobic') and oxidative phosphorylation by using reducing equivalents from carbohydrate and fat metabolism ('aerobic'). The relative contribution of these metabolic pathways is primarily determined by the intensity and duration of exercise. For most events at the Olympics, carbohydrate is the primary fuel for anaerobic and aerobic metabolism. Here, we provide an overview of exercise metabolism and the key regulatory mechanisms ensuring that ATP resynthesis is closely matched to the ATP demand of exercise. We also summarize various interventions that target muscle metabolism for ergogenic benefit in athletic events.
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Affiliation(s)
- Mark Hargreaves
- Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia.
| | - Lawrence L Spriet
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
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12
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Miotto PM, Petrick HL, Holloway GP. Acute insulin deprivation results in altered mitochondrial substrate sensitivity conducive to greater fatty acid transport. Am J Physiol Endocrinol Metab 2020; 319:E345-E353. [PMID: 32543943 PMCID: PMC7473910 DOI: 10.1152/ajpendo.00495.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Type 1 and type 2 diabetes are both tightly associated with impaired glucose control. Although both pathologies stem from different mechanisms, a reduction in insulin action coincides with drastic metabolic dysfunction in skeletal muscle and metabolic inflexibility. However, the underlying explanation for this response remains poorly understood, particularly since it is difficult to distinguish the role of attenuated insulin action from the detrimental effects of reactive lipid accumulation, which impairs mitochondrial function and promotes reactive oxygen species (ROS) emission. We therefore utilized streptozotocin to examine the effects of acute insulin deprivation, in the absence of a high-lipid/nutrient excess environment, on the regulation of mitochondrial substrate sensitivity and ROS emission. The ablation of insulin resulted in reductions in absolute mitochondrial oxidative capacity and ADP-supported respiration and reduced the ability for malonyl-CoA to inhibit carnitine palmitoyltransferase I (CPT-I) and suppress fatty acid-supported respiration. These bioenergetic responses coincided with increased mitochondrial-derived H2O2 emission and lipid transporter content, independent of major mitochondrial substrate transporter proteins and enzymes involved in fatty acid oxidation. Together, these data suggest that attenuated/ablated insulin signaling does not affect mitochondrial ADP sensitivity, whereas the increased reliance on fatty acid oxidation in situations where insulin action is reduced may occur as a result of altered regulation of mitochondrial fatty acid transport through CPT-I.
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Affiliation(s)
- Paula M Miotto
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Heather L Petrick
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Graham P Holloway
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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13
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Buch BT, Halling JF, Ringholm S, Gudiksen A, Kjøbsted R, Olsen MA, Wojtaszewski JFP, Pilegaard H. Colchicine treatment impairs skeletal muscle mitochondrial function and insulin sensitivity in an age‐specific manner. FASEB J 2020; 34:8653-8670. [DOI: 10.1096/fj.201903113rr] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 12/20/2022]
Affiliation(s)
| | | | - Stine Ringholm
- Department of Biology University of Copenhagen Copenhagen Denmark
| | - Anders Gudiksen
- Department of Biology University of Copenhagen Copenhagen Denmark
| | - Rasmus Kjøbsted
- Department of Nutrition, Exercise and Sports University of Copenhagen Copenhagen Denmark
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14
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Barbeau PA, Houad JM, Huber JS, Paglialunga S, Snook LA, Herbst EAF, Dennis KMJH, Simpson JA, Holloway GP. Ablating the Rab-GTPase activating protein TBC1D1 predisposes rats to high-fat diet-induced cardiomyopathy. J Physiol 2020; 598:683-697. [PMID: 31845331 DOI: 10.1113/jp279042] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 12/12/2019] [Indexed: 01/08/2023] Open
Abstract
KEY POINTS Although the role of TBC1D1 within the heart remains unknown, expression of TBC1D1 increases in the left ventricle following an acute infarction, suggesting a biological importance within this tissue. We investigated the mechanistic role of TBC1D1 within the heart, aiming to establish the consequences of attenuating TBC1D1 signalling in the development of diabetic cardiomyopathy, as well as to determine potential sex differences. TBC1D1 ablation increased plasma membrane fatty acid binding protein content and myocardial palmitate oxidation. Following high-fat feeding, TBC1D1 ablation dramatically increased fibrosis and induced end-diastolic dysfunction in both male and female rats in the absence of changes in mitochondrial bioenergetics. Altogether, independent of sex, ablating TBC1D1 predisposes the left ventricle to pathological remodelling following high-fat feeding, and suggests TBC1D1 protects against diabetic cardiomyopathy. ABSTRACT TBC1D1, a Rab-GTPase activating protein, is involved in the regulation of glucose handling and substrate metabolism within skeletal muscle, and is essential for maintaining pancreatic β-cell mass and insulin secretion. However, the function of TBC1D1 within the heart is largely unknown. Therefore, we examined the role of TBC1D1 in the left ventricle and the functional consequence of ablating TBC1D1 on the susceptibility to high-fat diet-induced abnormalities. Since mutations within TBC1D1 (R125W) display stronger associations with clinical parameters in women, we further examined possible sex differences in the predisposition to diabetic cardiomyopathy. In control-fed animals, TBC1D1 ablation did not alter insulin-stimulated glucose uptake, or echocardiogram parameters, but increased accumulation of a plasma membrane fatty acid transporter and the capacity for palmitate oxidation. When challenged with an 8 week high-fat diet, TBC1D1 knockout rats displayed a four-fold increase in fibrosis compared to wild-type animals, and this was associated with diastolic dysfunction, suggesting a predisposition to diet-induced cardiomyopathy. Interestingly, high-fat feeding only induced cardiac hypertrophy in male TBC1D1 knockout animals, implicating a possible sex difference. Mitochondrial respiratory capacity and substrate sensitivity to pyruvate and ADP were not altered by diet or TBC1D1 ablation, nor were markers of oxidative stress, or indices of overt heart failure. Altogether, independent of sex, ablation of TBC1D1 not only increased the susceptibility to high-fat diet-induced diastolic dysfunction and left ventricular fibrosis, independent of sex, but also predisposed male animals to the development of cardiac hypertrophy. These data suggest that TBC1D1 may exert cardioprotective effects in the development of diabetic cardiomyopathy.
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Affiliation(s)
- Pierre-Andre Barbeau
- Department of Human Health & Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Jacy M Houad
- Department of Human Health & Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Jason S Huber
- Department of Human Health & Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Sabina Paglialunga
- Department of Human Health & Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Laelie A Snook
- Department of Human Health & Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Eric A F Herbst
- Department of Human Health & Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Kaitlyn M J H Dennis
- Department of Human Health & Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Jeremy A Simpson
- Department of Human Health & Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Graham P Holloway
- Department of Human Health & Nutritional Sciences, University of Guelph, Ontario, Canada
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15
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Holloway GP, Holwerda AM, Miotto PM, Dirks ML, Verdijk LB, van Loon LJC. Age-Associated Impairments in Mitochondrial ADP Sensitivity Contribute to Redox Stress in Senescent Human Skeletal Muscle. Cell Rep 2019. [PMID: 29539414 DOI: 10.1016/j.celrep.2018.02.069] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
It remains unknown if mitochondrial bioenergetics are altered with aging in humans. We established an in vitro method to simultaneously determine mitochondrial respiration and H2O2 emission in skeletal muscle tissue across a range of biologically relevant ADP concentrations. Using this approach, we provide evidence that, although the capacity for mitochondrial H2O2 emission is not increased with aging, mitochondrial ADP sensitivity is impaired. This resulted in an increase in mitochondrial H2O2 and the fraction of electron leak to H2O2, in the presence of virtually all ADP concentrations examined. Moreover, although prolonged resistance training in older individuals increased muscle mass, strength, and maximal mitochondrial respiration, exercise training did not alter H2O2 emission rates in the presence of ADP, the fraction of electron leak to H2O2, or the redox state of the muscle. These data establish that a reduction in mitochondrial ADP sensitivity increases mitochondrial H2O2 emission and contributes to age-associated redox stress.
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Affiliation(s)
- Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Andrew M Holwerda
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, 6200 Maastricht, the Netherlands
| | - Paula M Miotto
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Marlou L Dirks
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, 6200 Maastricht, the Netherlands
| | - Lex B Verdijk
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, 6200 Maastricht, the Netherlands
| | - Luc J C van Loon
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, 6200 Maastricht, the Netherlands
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16
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Halling JF, Jessen H, Nøhr-Meldgaard J, Buch BT, Christensen NM, Gudiksen A, Ringholm S, Neufer PD, Prats C, Pilegaard H. PGC-1α regulates mitochondrial properties beyond biogenesis with aging and exercise training. Am J Physiol Endocrinol Metab 2019; 317:E513-E525. [PMID: 31265325 DOI: 10.1152/ajpendo.00059.2019] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Impaired mitochondrial function has been implicated in the pathogenesis of age-associated metabolic diseases through regulation of cellular redox balance. Exercise training is known to promote mitochondrial biogenesis in part through induction of the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). Recently, mitochondrial ADP sensitivity has been linked to reactive oxygen species (ROS) emission with potential impact on age-associated physiological outcomes, but the underlying molecular mechanisms remain unclear. Therefore, the present study investigated the effects of aging and exercise training on mitochondrial properties beyond biogenesis, including respiratory capacity, ADP sensitivity, ROS emission, and mitochondrial network structure, in myofibers from inducible muscle-specific PGC-1α-knockout mice and control mice. Aged mice displayed lower running endurance and mitochondrial respiratory capacity than young mice. This was associated with intermyofibrillar mitochondrial network fragmentation, diminished submaximal ADP-stimulated respiration, increased mitochondrial ROS emission, and oxidative stress. Exercise training reversed the decline in maximal respiratory capacity independent of PGC-1α, whereas exercise training rescued the age-related mitochondrial network fragmentation and the impaired submaximal ADP-stimulated respiration in a PGC-1α-dependent manner. Furthermore, lack of PGC-1α was associated with altered phosphorylation and carbonylation of the inner mitochondrial membrane ADP/ATP exchanger adenine nucleotide translocase 1. In conclusion, the present study provides evidence that PGC-1α regulates submaximal ADP-stimulated respiration, ROS emission, and mitochondrial network structure in mouse skeletal muscle during aging and exercise training.
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Affiliation(s)
- Jens Frey Halling
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Henrik Jessen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Nøhr-Meldgaard
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Bjørg Thiellesen Buch
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Anders Gudiksen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Stine Ringholm
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, Departments of Physiology and Kinesiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Clara Prats
- Core Facility for Integrated Microscopy, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Pilegaard
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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17
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18
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Petrick HL, Pignanelli C, Barbeau PA, Churchward-Venne TA, Dennis KMJH, van Loon LJC, Burr JF, Goossens GH, Holloway GP. Blood flow restricted resistance exercise and reductions in oxygen tension attenuate mitochondrial H 2 O 2 emission rates in human skeletal muscle. J Physiol 2019; 597:3985-3997. [PMID: 31194254 DOI: 10.1113/jp277765] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 06/07/2019] [Indexed: 12/23/2022] Open
Abstract
KEY POINTS Blood flow restricted resistance exercise (BFR-RE) is capable of inducing comparable adaptations to traditional resistance exercise (RE), despite a lower total exercise volume. It has been suggested that an increase in reactive oxygen species (ROS) production may be involved in this response; however, oxygen partial pressure ( P O 2 ) is reduced during BFR-RE, and the influence of P O 2 on mitochondrial redox balance remains poorly understood. In human skeletal muscle tissue, we demonstrate that both maximal and submaximal mitochondrial ROS emission rates are acutely decreased 2 h following BFR-RE, but not RE, occurring along with a reduction in tissue oxygenation during BFR-RE. We further suggest that P O 2 is involved in this response because an in vitro analysis revealed that reducing P O 2 dramatically decreased mitochondrial ROS emissions and electron leak to ROS. Altogether, these data indicate that mitochondrial ROS emission rates are attenuated following BFR-RE, and such a response is likely influenced by reductions in P O 2 . ABSTRACT Low-load blood flow restricted resistance exercise (BFR-RE) training has been proposed to induce comparable adaptations to traditional resistance exercise (RE) training, however, the acute signalling events remain unknown. Although a suggested mechanism of BFR-RE is an increase in reactive oxygen species (ROS) production, oxygen partial pressure ( P O 2 ) is reduced during BFR-RE, and the influence of O2 tension on mitochondrial redox balance remains ambiguous. We therefore aimed to determine whether skeletal muscle mitochondrial bioenergetics were altered following an acute bout of BFR-RE or RE, and to further examine the role of P O 2 in this response. Accordingly, muscle biopsies were obtained from 10 males at rest and 2 h after performing three sets of single-leg squats (RE or BFR-RE) to failure at 30% one-repetition maximum. We determined that mitochondrial respiratory capacity and ADP sensitivity were not altered in response to RE or BFR-RE. Although maximal (succinate) and submaximal (non-saturating ADP) mitochondrial ROS emission rates were unchanged following RE, BFR-RE attenuated these responses by ∼30% compared to pre-exercise, occurring along with a reduction in skeletal muscle tissue oxygenation during BFR-RE (P < 0.01 vs. RE). In a separate cohort of participants, evaluation of mitochondrial bioenergetics in vitro revealed that mild O2 restriction (50 µm) dramatically attenuated maximal (∼4-fold) and submaximal (∼50-fold) mitochondrial ROS emission rates and the fraction of electron leak to ROS compared to room air (200 µm). Combined, these data demonstrate that mitochondrial ROS emissions are attenuated following BFR-RE, a response which may be mediated by a reduction in skeletal muscle P O 2 .
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Affiliation(s)
- Heather L Petrick
- Human Health & Nutritional Science, University of Guelph, Guelph, Ontario, Canada
| | | | - Pierre-Andre Barbeau
- Human Health & Nutritional Science, University of Guelph, Guelph, Ontario, Canada
| | - Tyler A Churchward-Venne
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada.,Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Kaitlyn M J H Dennis
- Human Health & Nutritional Science, University of Guelph, Guelph, Ontario, Canada
| | - Luc J C van Loon
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Jamie F Burr
- Human Health & Nutritional Science, University of Guelph, Guelph, Ontario, Canada
| | - Gijs H Goossens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Graham P Holloway
- Human Health & Nutritional Science, University of Guelph, Guelph, Ontario, Canada
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19
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Layec G, Blain GM, Rossman MJ, Park SY, Hart CR, Trinity JD, Gifford JR, Sidhu SK, Weavil JC, Hureau TJ, Amann M, Richardson RS. Acute High-Intensity Exercise Impairs Skeletal Muscle Respiratory Capacity. Med Sci Sports Exerc 2019; 50:2409-2417. [PMID: 30102675 DOI: 10.1249/mss.0000000000001735] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE The effect of an acute bout of exercise, especially high-intensity exercise, on the function of mitochondrial respiratory complexes is not well understood, with potential implications for both the healthy population and patients undergoing exercise-based rehabilitation. Therefore, this study sought to comprehensively examine respiratory flux through the different complexes of the electron transport chain in skeletal muscle mitochondria before and immediately after high-intensity aerobic exercise. METHODS Muscle biopsies of the vastus lateralis were obtained at baseline and immediately after a 5-km time trial performed on a cycle ergometer. Mitochondrial respiratory flux through the complexes of the electron transport chain was measured in permeabilized skeletal muscle fibers by high-resolution respirometry. RESULTS Complex I + II state 3 (state 3CI + CII) respiration, a measure of oxidative phosphorylation capacity, was diminished immediately after the exercise (pre, 27 ± 3 ρm·mg·s; post, 17 ± 2 ρm·mg·s; P < 0.05). This decreased oxidative phosphorylation capacity was predominantly the consequence of attenuated complex II-driven state 3 (state 3CII) respiration (pre, 17 ± 1 ρm·mg·s; post, 9 ± 2 ρm·mg·s; P < 0.05). Although complex I-driven state 3 (3CI) respiration was also lower (pre, 20 ± 2 ρm·mg·s; post, 14 ± 4 ρm·mg·s), this did not reach statistical significance (P = 0.27). In contrast, citrate synthase activity, proton leak (state 2 respiration), and complex IV capacity were not significantly altered immediately after the exercise. CONCLUSIONS These findings reveal that acute high-intensity aerobic exercise significantly inhibits skeletal muscle state 3CII and oxidative phosphorylation capacity. This, likely transient, mitochondrial defect might amplify the exercise-induced development of fatigue and play an important role in initiating exercise-induced mitochondrial adaptations.
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Affiliation(s)
- Gwenael Layec
- Department of Medicine, University of Utah, Salt Lake City, UT.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT.,Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT
| | | | - Matthew J Rossman
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| | - Song Y Park
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| | - Corey R Hart
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| | - Joel D Trinity
- Department of Medicine, University of Utah, Salt Lake City, UT.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT.,Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT
| | - Jayson R Gifford
- Department of Medicine, University of Utah, Salt Lake City, UT.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT.,Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT
| | - Simranjit K Sidhu
- Department of Medicine, University of Utah, Salt Lake City, UT.,Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, AUSTRALIA
| | - Joshua C Weavil
- Department of Medicine, University of Utah, Salt Lake City, UT
| | - Thomas J Hureau
- Department of Medicine, University of Utah, Salt Lake City, UT.,Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT.,Mitochondria, Oxidative Stress and Muscular Protection Laboratory, EA 3072, University of Strasbourg, Strasbourg, FRANCE
| | - Markus Amann
- Department of Medicine, University of Utah, Salt Lake City, UT.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT.,Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT
| | - Russell S Richardson
- Department of Medicine, University of Utah, Salt Lake City, UT.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT.,Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, UT
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20
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Hughes MC, Ramos SV, Turnbull PC, Rebalka IA, Cao A, Monaco CM, Varah NE, Edgett BA, Huber JS, Tadi P, Delfinis LJ, Schlattner U, Simpson JA, Hawke TJ, Perry CG. Early myopathy in Duchenne muscular dystrophy is associated with elevated mitochondrial H 2 O 2 emission during impaired oxidative phosphorylation. J Cachexia Sarcopenia Muscle 2019; 10:643-661. [PMID: 30938481 PMCID: PMC6596403 DOI: 10.1002/jcsm.12405] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 12/13/2018] [Accepted: 01/09/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Muscle wasting and weakness in Duchenne muscular dystrophy (DMD) causes severe locomotor limitations and early death due in part to respiratory muscle failure. Given that current clinical practice focuses on treating secondary complications in this genetic disease, there is a clear need to identify additional contributions in the aetiology of this myopathy for knowledge-guided therapy development. Here, we address the unresolved question of whether the complex impairments observed in DMD are linked to elevated mitochondrial H2 O2 emission in conjunction with impaired oxidative phosphorylation. This study performed a systematic evaluation of the nature and degree of mitochondrial-derived H2 O2 emission and mitochondrial oxidative dysfunction in a mouse model of DMD by designing in vitro bioenergetic assessments that attempt to mimic in vivo conditions known to be critical for the regulation of mitochondrial bioenergetics. METHODS Mitochondrial bioenergetics were compared with functional and histopathological indices of myopathy early in DMD (4 weeks) in D2.B10-DMDmdx /2J mice (D2.mdx)-a model that demonstrates severe muscle weakness. Adenosine diphosphate's (ADP's) central effect of attenuating H2 O2 emission while stimulating respiration was compared under two models of mitochondrial-cytoplasmic phosphate exchange (creatine independent and dependent) in muscles that stained positive for membrane damage (diaphragm, quadriceps, and white gastrocnemius). RESULTS Pathway-specific analyses revealed that Complex I-supported maximal H2 O2 emission was elevated concurrent with a reduced ability of ADP to attenuate emission during respiration in all three muscles (mH2 O2 : +17 to +197% in D2.mdx vs. wild type). This was associated with an impaired ability of ADP to stimulate respiration at sub-maximal and maximal kinetics (-17 to -72% in D2.mdx vs. wild type), as well as a loss of creatine-dependent mitochondrial phosphate shuttling in diaphragm and quadriceps. These changes largely occurred independent of mitochondrial density or abundance of respiratory chain complexes, except for quadriceps. This muscle was also the only one exhibiting decreased calcium retention capacity, which indicates increased sensitivity to calcium-induced permeability transition pore opening. Increased H2 O2 emission was accompanied by a compensatory increase in total glutathione, while oxidative stress markers were unchanged. Mitochondrial bioenergetic dysfunctions were associated with induction of mitochondrial-linked caspase 9, necrosis, and markers of atrophy in some muscles as well as reduced hindlimb torque and reduced respiratory muscle function. CONCLUSIONS These results provide evidence that Complex I dysfunction and loss of central respiratory control by ADP and creatine cause elevated oxidant generation during impaired oxidative phosphorylation. These dysfunctions may contribute to early stage disease pathophysiology and support the growing notion that mitochondria are a potential therapeutic target in this disease.
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Affiliation(s)
- Meghan C. Hughes
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - Sofhia V. Ramos
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - Patrick C. Turnbull
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - Irena A. Rebalka
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Andrew Cao
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Cynthia M.F. Monaco
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Nina E. Varah
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Brittany A. Edgett
- Department of Human Health and Nutritional Sciences and Cardiovascular Research GroupUniversity of GuelphGuelphONCanada
| | - Jason S. Huber
- Department of Human Health and Nutritional Sciences and Cardiovascular Research GroupUniversity of GuelphGuelphONCanada
| | - Peyman Tadi
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - Luca J. Delfinis
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - U. Schlattner
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy)University Grenoble AlpesGrenobleFrance
| | - Jeremy A. Simpson
- Department of Human Health and Nutritional Sciences and Cardiovascular Research GroupUniversity of GuelphGuelphONCanada
| | - Thomas J. Hawke
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Christopher G.R. Perry
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
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21
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Chang L, Daly C, Miller DM, Allen PD, Boyle JP, Hopkins PM, Shaw MA. Permeabilised skeletal muscle reveals mitochondrial deficiency in malignant hyperthermia-susceptible individuals. Br J Anaesth 2019; 122:613-621. [PMID: 30916033 DOI: 10.1016/j.bja.2019.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/26/2019] [Accepted: 02/04/2019] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Individuals genetically susceptible to malignant hyperthermia (MH) exhibit hypermetabolic reactions when exposed to volatile anaesthetics. Mitochondrial dysfunction has previously been associated with the MH-susceptible (MHS) phenotype in animal models, but evidence of this in human MH is limited. METHODS We used high resolution respirometry to compare oxygen consumption rates (oxygen flux) between permeabilised human MHS and MH-negative (MHN) skeletal muscle fibres with or without prior exposure to halothane. A substrate-uncoupler-inhibitor titration protocol was used to measure the following components of the electron transport chain under conditions of oxidative phosphorylation (OXPHOS) or after uncoupling the electron transport system (ETS): complex I (CI), complex II (CII), CI+CII and, as a measure of mitochondrial mass, complex IV (CIV). RESULTS Baseline comparisons without halothane exposure showed significantly increased mitochondrial mass (CIV, P=0.021) but lower flux control ratios in CI+CII(OXPHOS) and CII(ETS) of MHS mitochondria compared with MHN (P=0.033 and 0.005, respectively) showing that human MHS mitochondria have a functional deficiency. Exposure to halothane triggered a hypermetabolic response in MHS mitochondria, significantly increasing mass-specific oxygen flux in CI(OXPHOS), CI+CII(OXPHOS), CI+CII(ETS), and CII(ETS) (P=0.001-0.012), while the rates in MHN samples were unaltered by halothane exposure. CONCLUSIONS We present evidence of mitochondrial dysfunction in human MHS skeletal muscle both at baseline and after halothane exposure.
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Affiliation(s)
- Leon Chang
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK
| | - Catherine Daly
- Malignant Hyperthermia Unit, St James's University Hospital, Leeds, UK
| | - Dorota M Miller
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK
| | - Paul D Allen
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK
| | - John P Boyle
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Philip M Hopkins
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK; Malignant Hyperthermia Unit, St James's University Hospital, Leeds, UK.
| | - Marie-Anne Shaw
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK
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22
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High intensity exercise inhibits carnitine palmitoyltransferase-I sensitivity to l-carnitine. Biochem J 2019; 476:547-558. [DOI: 10.1042/bcj20180849] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/08/2019] [Accepted: 01/11/2019] [Indexed: 11/17/2022]
Abstract
Abstract
The decline in fat oxidation at higher power outputs of exercise is a complex interaction between several mechanisms; however, the influence of mitochondrial bioenergetics in this process remains elusive. Therefore, using permeabilized muscle fibers from mouse skeletal muscle, we aimed to determine if acute exercise altered mitochondrial sensitivity to (1) adenosine diphosphate (ADP) and inorganic phosphate (Pi), or (2) carnitine palmitoyltransferase-I (CPT-I) independent (palmitoylcarnitine, PC) and dependent [palmitoyl-CoA (P-CoA), malonyl-CoA (M-CoA), and l-carnitine] substrates, in an intensity-dependent manner. As the apparent ADP Km increased to a similar extent following low (LI) and high (HI) intensity exercise compared with sedentary (SED) animals, and Pi sensitivity was unaltered by exercise, regulation of phosphate provision likely does not contribute to the well-established intensity-dependent shift in substrate utilization. Mitochondrial sensitivity to PC and P-CoA was not influenced by exercise, while M-CoA sensitivity was attenuated similarly following LI and HI. In contrast, CPT-I sensitivity to l-carnitine was only altered following HI, as HI exercise attenuated l-carnitine sensitivity by ∼40%. Moreover, modeling the in vivo concentrations of l-carnitine and P-CoA during exercise suggests that CPT-I flux is ∼25% lower following HI, attributed equally to reductions in l-carnitine content and l-carnitine sensitivity. Altogether, these data further implicate CPT-I flux as a key event influencing metabolic interactions during exercise, as a decline in l-carnitine sensitivity in addition to availability at higher power outputs could impair mitochondrial fatty acid oxidation.
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23
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Brunetta HS, de Paula GC, de Oliveira J, Martins EL, Dos Santos GJ, Galina A, Rafacho A, de Bem AF, Nunes EA. Decrement in resting and insulin-stimulated soleus muscle mitochondrial respiration is an early event in diet-induced obesity in mice. Exp Physiol 2019; 104:306-321. [PMID: 30578638 DOI: 10.1113/ep087317] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 12/19/2018] [Indexed: 01/08/2023]
Abstract
NEW FINDINGS What is the central question of this study? What are the temporal responses of mitochondrial respiration and mitochondrial responsivity to insulin in soleus muscle fibres from mice during the development of obesity and insulin resistance? What is the main finding and its importance? Short- and long-term feeding with a high-fat diet markedly reduced soleus mitochondrial respiration and mitochondrial responsivity to insulin before any change in glycogen synthesis. Muscle glycogen synthesis and whole-body insulin resistance were present after 14 and 28 days, respectively. Our findings highlight the plasticity of mitochondria during the development of obesity and insulin resistance. ABSTRACT Recently, significant attention has been given to the role of muscle mitochondrial function in the development of insulin resistance associated with obesity. Our aim was to investigate temporal alterations in mitochondrial respiration, H2 O2 emission and mitochondrial responsivity to insulin in permeabilized skeletal muscle fibres during the development of obesity in mice. Male Swiss mice (5-6 weeks old) were fed with a high-fat diet (60% calories from fat) or standard diet for 7, 14 or 28 days to induce obesity and insulin resistance. Diet-induced obese (DIO) mice presented with reduced glucose tolerance and hyperinsulinaemia after 7 days of high-fat diet. After 14 days, the expected increase in muscle glycogen content after systemic injection of glucose and insulin was not observed in DIO mice. At 28 days, blood glucose decay after insulin injection was significantly impaired. Complex I (pyruvate + malate) and II (succinate)-linked respiration and oxidative phosphorylation (ADP) were decreased after 7 days of high-fat diet and remained low in DIO mice after 14 and 28 days of treatment. Moreover, mitochondria from DIO mice were incapable of increasing respiratory coupling and ADP responsivity after insulin stimulation in all observed periods. Markers of mitochondrial content were reduced only after 28 days of treatment. The mitochondrial H2 O2 emission profile varied during the time course of DIO, with a reduction of H2 O2 emission in the early stages of DIO and an increased emission after 28 days of treatment. Our data demonstrate that DIO promotes transitory alterations in mitochondrial physiology during the early and late stages of insulin resistance related to obesity.
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Affiliation(s)
- Henver Simionato Brunetta
- Multicenter Graduate Program in Physiological Sciences, Federal University of Santa Catarina, Florianopólis, Santa Catrina, Brazil
| | - Gabriela Cristina de Paula
- Graduate Program in Biochemistry, Federal University of Santa Catarina, Florianopólis, Santa Catrina, Brazil
| | - Jade de Oliveira
- Graduate Program in Health Sciences, University of Extremo Sul Catarinense, Criciúma, Santa Catarina, Brazil
| | - Eduarda Lopes Martins
- Graduate Program in Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gustavo Jorge Dos Santos
- Multicenter Graduate Program in Physiological Sciences, Federal University of Santa Catarina, Florianopólis, Santa Catrina, Brazil
| | - Antonio Galina
- Graduate Program in Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Alex Rafacho
- Multicenter Graduate Program in Physiological Sciences, Federal University of Santa Catarina, Florianopólis, Santa Catrina, Brazil
| | - Andreza Fabro de Bem
- Graduate Program in Biochemistry, Federal University of Santa Catarina, Florianopólis, Santa Catrina, Brazil.,Department of Physiological Sciences, Institute of Biological Sciences, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Everson Araújo Nunes
- Multicenter Graduate Program in Physiological Sciences, Federal University of Santa Catarina, Florianopólis, Santa Catrina, Brazil
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Miotto PM, LeBlanc PJ, Holloway GP. High-Fat Diet Causes Mitochondrial Dysfunction as a Result of Impaired ADP Sensitivity. Diabetes 2018; 67:2199-2205. [PMID: 29980534 DOI: 10.2337/db18-0417] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 06/26/2018] [Indexed: 11/13/2022]
Abstract
Although molecular approaches altering mitochondrial content have implied a direct relationship between mitochondrial bioenergetics and insulin sensitivity, paradoxically, consumption of a high-fat (HF) diet increases mitochondrial content while inducing insulin resistance. We hypothesized that despite the induction of mitochondrial biogenesis, consumption of an HF diet would impair mitochondrial ADP sensitivity in skeletal muscle of mice and therefore manifest in mitochondrial dysfunction in the presence of ADP concentrations indicative of skeletal muscle biology. We found that HF consumption increased mitochondrial protein expression; however, absolute mitochondrial respiration and ADP sensitivity were impaired across a range of biologically relevant ADP concentrations. In addition, HF consumption attenuated the ability of ADP to suppress mitochondrial H2O2 emission, further suggesting impairments in ADP sensitivity. The abundance of ADP transport proteins were not altered, but the sensitivity to carboxyatractyloside-mediated inhibition was attenuated after HF consumption, implicating alterations in adenine nucleotide translocase (ANT) ADP sensitivity in these observations. Moreover, palmitoyl-CoA is known to inhibit ANT, and modeling intramuscular palmitoyl-CoA concentrations that occur after HF consumption exacerbated the deficiency in ADP sensitivity. Altogether, these data suggest that an HF diet induces mitochondrial dysfunction secondary to an intrinsic impairment in mitochondrial ADP sensitivity that is magnified by palmitoyl-CoA.
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Affiliation(s)
- Paula M Miotto
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Mitochondrial-derived reactive oxygen species influence ADP sensitivity, but not CPT-I substrate sensitivity. Biochem J 2018; 475:2997-3008. [PMID: 30111574 DOI: 10.1042/bcj20180419] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 07/26/2018] [Accepted: 08/13/2018] [Indexed: 02/06/2023]
Abstract
The mechanisms regulating oxidative phosphorylation during exercise remain poorly defined; however, key mitochondrial proteins, including carnitine palmitoyltransferase-I (CPT-I) and adenine nucleotide translocase, have redox-sensitive sites. Interestingly, muscle contraction has recently been shown to increase mitochondrial membrane potential and reactive oxygen species (ROS) production; therefore, we aimed to determine if mitochondrial-derived ROS influences bioenergetic responses to exercise. Specifically, we examined the influence of acute exercise on mitochondrial bioenergetics in WT (wild type) and transgenic mice (MCAT, mitochondrial-targeted catalase transgenic) possessing attenuated mitochondrial ROS. We found that ablating mitochondrial ROS did not alter palmitoyl-CoA (P-CoA) respiratory kinetics or influence the exercise-mediated reductions in malonyl CoA sensitivity, suggesting that mitochondrial ROS does not regulate CPT-I. In contrast, while mitochondrial protein content, maximal coupled respiration, and ADP (adenosine diphosphate) sensitivity in resting muscle were unchanged in the absence of mitochondrial ROS, exercise increased the apparent ADP K m (decreased ADP sensitivity) ∼30% only in WT mice. Moreover, while the presence of P-CoA decreased ADP sensitivity, it did not influence the basic response to exercise, as the apparent ADP K m was increased only in the presence of mitochondrial ROS. This basic pattern was also mirrored in the ability of ADP to suppress mitochondrial H2O2 emission rates, as exercise decreased the suppression of H2O2 only in WT mice. Altogether, these data demonstrate that while exercise-induced mitochondrial-derived ROS does not influence CPT-I substrate sensitivity, it inhibits ADP sensitivity independent of P-CoA. These data implicate mitochondrial redox signaling as a regulator of oxidative phosphorylation.
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Dohlmann TL, Hindsø M, Dela F, Helge JW, Larsen S. High-intensity interval training changes mitochondrial respiratory capacity differently in adipose tissue and skeletal muscle. Physiol Rep 2018; 6:e13857. [PMID: 30221839 PMCID: PMC6139713 DOI: 10.14814/phy2.13857] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 08/15/2018] [Accepted: 08/16/2018] [Indexed: 02/04/2023] Open
Abstract
The effect of high-intensity training (HIT) on mitochondrial ADP sensitivity and respiratory capacity was investigated in human skeletal muscle and subcutaneous adipose tissue (SAT). Twelve men and women underwent 6 weeks of HIT (7 × 1 min at app. 100% of maximal oxygen uptake (VO2max )). Mitochondrial respiration was measured in permeabilized muscle fibers and in abdominal SAT. Mitochondrial ADP sensitivity was determined using Michaelis Menten enzyme kinetics. VO2max , body composition and citrate synthase (CS) activity (skeletal muscle) and mtDNA (SAT) were measured before and after training. VO2max increased from 2.6 ± 0.2 to 2.8 ± 0.2 L O2 /min (P = 0.011) accompanied by a decreased mitochondrial ADP sensitivity in skeletal muscle (Km : 0.14 ± 0.02 to 0.29 ± 0.03 mmol/L ADP (P = 0.002)), with no changes in SAT (Km : 0.12 ± 0.02 to 0.16 ± 0.05 mmol/L ADP; P = 0.186), following training. Mitochondrial respiratory capacity increased in skeletal muscle from 57 ± 4 to 67 ± 4 pmol O2 ·mg-1 ·sec-1 (P < 0.001), but decreased with training in SAT from 1.3 ± 0.1 to 1.0 ± 0.1 pmol O2 ·mg-1 ·sec-1 (P < 0.001). CS activity increased (P = 0.027) and mtDNA was unchanged following training. Intrinsic mitochondrial respiratory capacity was unchanged in skeletal muscle, but increased in SAT after HIT. In summary, our results demonstrate that mitochondrial adaptations to HIT in skeletal muscle are comparable to adaptations to endurance training, with an increased mitochondrial respiratory capacity and CS activity. However, mitochondria in SAT adapts differently compared to skeletal muscle mitochondria, where mitochondrial respiratory capacity decreased and mtDNA remained unchanged after HIT.
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Affiliation(s)
- Tine L. Dohlmann
- XlabCenter for Healthy AgingDepartment of Biomedical SciencesFaculty of Health SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Morten Hindsø
- XlabCenter for Healthy AgingDepartment of Biomedical SciencesFaculty of Health SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Flemming Dela
- XlabCenter for Healthy AgingDepartment of Biomedical SciencesFaculty of Health SciencesUniversity of CopenhagenCopenhagenDenmark
- Department of GeriatricsBispebjerg University HospitalCopenhagenDenmark
| | - Jørn W. Helge
- XlabCenter for Healthy AgingDepartment of Biomedical SciencesFaculty of Health SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Steen Larsen
- XlabCenter for Healthy AgingDepartment of Biomedical SciencesFaculty of Health SciencesUniversity of CopenhagenCopenhagenDenmark
- Clinical Research CentreMedical University of BialystokBialystokPoland
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Abstract
Isoforms of creatine kinase (CK) generate and use phosphocreatine, a concentrated and highly diffusible cellular "high energy" intermediate, for the main purpose of energy buffering and transfer in order to maintain cellular energy homeostasis. The mitochondrial CK isoform (mtCK) localizes to the mitochondrial intermembrane and cristae space, where it assembles into peripherally membrane-bound, large cuboidal homooctamers. These are part of proteolipid complexes wherein mtCK directly interacts with cardiolipin and other anionic phospholipids, as well as with the VDAC channel in the outer membrane. This leads to a stabilization and cross-linking of inner and outer mitochondrial membrane, forming so-called contact sites. Also the adenine nucleotide translocator of the inner membrane can be recruited into these proteolipid complexes, probably mediated by cardiolipin. The complexes have functions mainly in energy transfer to the cytosol and stimulation of oxidative phosphorylation, but also in restraining formation of reactive oxygen species and apoptosis. In vitro evidence indicates a putative role of mtCK in mitochondrial phospholipid distribution, and most recently a role in thermogenesis has been proposed. This review summarizes the essential structural and functional data of these mtCK complexes and describes in more detail the more recent advances in phospholipid interaction, thermogenesis, cancer and evolution of mtCK.
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Holloway GP. Nutrition and Training Influences on the Regulation of Mitochondrial Adenosine Diphosphate Sensitivity and Bioenergetics. Sports Med 2018; 47:13-21. [PMID: 28332118 PMCID: PMC5371621 DOI: 10.1007/s40279-017-0693-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Since the seminal finding almost 50 years ago that exercise training increases mitochondrial content in skeletal muscle, a considerable amount of research has been dedicated to elucidate the mechanisms inducing mitochondrial biogenesis. The discovery of peroxisome proliferator-activated receptor γ co-activator 1α as a major regulator of exercise-induced gene transcription was instrumental in beginning to understand the signals regulating this process. However, almost two decades after its discovery, our understanding of the signals inducing mitochondrial biogenesis remain poorly defined, limiting our insights into possible novel training modalities in elite athletes that can increase the oxidative potential of muscle. In particular, the role of mitochondrial reactive oxygen species has received very little attention; however, several lifestyle interventions associated with an increase in mitochondrial reactive oxygen species coincide with the induction of mitochondrial biogenesis. Furthermore, the diminishing returns of exercise training are associated with reductions in exercise-induced, mitochondrial-derived reactive oxygen species. Therefore, research focused on altering redox signaling in elite athletes may prove to be effective at inducing mitochondrial biogenesis and augmenting training regimes. In the context of exercise performance, the biological effect of increasing mitochondrial content is an attenuated rise in free cytosolic adenosine diphosphate (ADP), and subsequently decreased carbohydrate flux at a given power output. Recent evidence has shown that mitochondrial ADP sensitivity is a regulated process influenced by nutritional interventions, acute exercise, and exercise training. This knowledge raises the potential to improve mitochondrial bioenergetics in the absence of changes in mitochondrial content. Elucidating the mechanisms influencing the acute regulation of mitochondrial ADP sensitivity could have performance benefits in athletes, especially as these individuals display high levels of mitochondria, and therefore are subjects in whom it is notoriously difficult to further induce mitochondrial adaptations. In addition to changes in ADP sensitivity, an increase in mitochondrial coupling would have a similar bioenergetic response, namely a reduction in free cytosolic ADP. While classically the stoichiometry of the electron transport chain has been considered rigid, recent evidence suggests that sodium nitrate can improve the efficiency of this process, creating the potential for dietary sources of nitrate (e.g., beetroot juice) to display similar improvements in exercise performance. The current review focuses on these processes, while also discussing the biological relevance in the context of exercise performance.
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Affiliation(s)
- Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, 491 Gordon St., Guelph, ON, N1G 2W1, Canada.
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29
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Willis WT, Miranda-Grandjean D, Hudgens J, Willis EA, Finlayson J, De Filippis EA, Zapata Bustos R, Langlais PR, Mielke C, Mandarino LJ. Dominant and sensitive control of oxidative flux by the ATP-ADP carrier in human skeletal muscle mitochondria: Effect of lysine acetylation. Arch Biochem Biophys 2018; 647:93-103. [PMID: 29653079 DOI: 10.1016/j.abb.2018.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 03/29/2018] [Accepted: 04/08/2018] [Indexed: 02/01/2023]
Abstract
The adenine nucleotide translocase (ANT) of the mitochondrial inner membrane exchanges ADP for ATP. Mitochondria were isolated from human vastus lateralis muscle (n = 9). Carboxyatractyloside titration of O2 consumption rate (Jo) at clamped [ADP] of 21 μM gave ANT abundance of 0.97 ± 0.14 nmol ANT/mg and a flux control coefficient of 82% ± 6%. Flux control fell to 1% ± 1% at saturating (2 mM) [ADP]. The KmADP for Jo was 32.4 ± 1.8 μM. In terms of the free (-3) ADP anion this KmADP was 12.0 ± 0.7 μM. A novel luciferase-based assay for ATP production gave KmADP of 13.1 ± 1.9 μM in the absence of ATP competition. The free anion KmADP in this case was 2.0 ± 0.3 μM. Targeted proteomic analyses showed significant acetylation of ANT Lysine23 and that ANT1 was the most abundant isoform. Acetylation of Lysine23 correlated positively with KmADP, r = 0.74, P = 0.022. The findings underscore the central role played by ANT in the control of oxidative phosphorylation, particularly at the energy phosphate levels associated with low ATP demand. As predicted by molecular dynamic modeling, ANT Lysine23 acetylation decreased the apparent affinity of ADP for ANT binding.
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Affiliation(s)
- W T Willis
- University of Arizona, College of Medicine, Department of Medicine, 1501 N. Campbell Avenue, P.O. Box 245099, Tucson, AZ 85724-5099, USA.
| | - D Miranda-Grandjean
- Mayo Clinic, Division of Endocrinology, East Shea Boulevard and 134th Street, Scottsdale, AZ 85259, USA.
| | - J Hudgens
- Mayo Clinic, Division of Endocrinology, East Shea Boulevard and 134th Street, Scottsdale, AZ 85259, USA.
| | - E A Willis
- Mayo Clinic, Division of Endocrinology, East Shea Boulevard and 134th Street, Scottsdale, AZ 85259, USA.
| | - J Finlayson
- University of Arizona, College of Medicine, Department of Medicine, 1501 N. Campbell Avenue, P.O. Box 245099, Tucson, AZ 85724-5099, USA.
| | - E A De Filippis
- Mayo Clinic, Division of Endocrinology, East Shea Boulevard and 134th Street, Scottsdale, AZ 85259, USA.
| | - R Zapata Bustos
- University of Arizona, College of Medicine, Department of Medicine, 1501 N. Campbell Avenue, P.O. Box 245099, Tucson, AZ 85724-5099, USA.
| | - P R Langlais
- University of Arizona, College of Medicine, Department of Medicine, 1501 N. Campbell Avenue, P.O. Box 245099, Tucson, AZ 85724-5099, USA.
| | - C Mielke
- Mayo Clinic, Division of Endocrinology, East Shea Boulevard and 134th Street, Scottsdale, AZ 85259, USA.
| | - L J Mandarino
- University of Arizona, College of Medicine, Department of Medicine, 1501 N. Campbell Avenue, P.O. Box 245099, Tucson, AZ 85724-5099, USA.
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Miotto PM, Holloway GP. Exercise-induced reductions in mitochondrial ADP sensitivity contribute to the induction of gene expression and mitochondrial biogenesis through enhanced mitochondrial H 2O 2 emission. Mitochondrion 2018; 46:116-122. [PMID: 29588219 DOI: 10.1016/j.mito.2018.03.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 01/23/2018] [Accepted: 03/21/2018] [Indexed: 01/04/2023]
Abstract
Acute exercise rapidly induces mitochondrial gene expression, however, the intracellular events regulating this process remain incompletely understood. The purpose of this study was to determine whether reductions in mitochondrial ADP sensitivity during exercise have a biological role in regulating mitochondrial-derived reactive oxygen species (ROS) production and the induction of mitochondrial biogenesis. Mitochondrial creatine kinase wildtype (WT) and knockout (KO) mice have divergent responses in ADP sensitivity during exercise, and we therefore used these mice to determine the relationship between mitochondrial ADP sensitivity, ROS production, and mitochondrial adaptations to exercise. In WT mice, acute exercise reduced mitochondrial ADP respiratory sensitivity and the ability of ADP to suppress ROS production, while increasing mitochondrial gene transcription (PGC-1α, PGC-1β and PDK4). In stark contrast, in KO mice, exercise increased ADP sensitivity, reduced mitochondrial ROS emission, and did not induce gene transcription. Despite the divergence in mRNA responses, exercise similarly induced calcium/calmodulin-dependent protein kinase II (CaMKII) and AMP-activated protein kinase (AMPK) phosphorylation in WT and KO mice, however only WT mice were associated with redox stress (4HNE). These data implicate acute changes in ADP sensitivity in mitochondrial adaptations to exercise. To further examine this we chronically exercise trained mice. While training increased mitochondrial content and reduced ADP sensitivity in WT mice, KO mice did not exhibit adaptations to exercise. Combined, these data suggest that exercise-induced attenuations in mitochondrial ADP sensitivity mediate redox signals that contribute to the induction of acute and chronic mitochondrial adaptations.
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Affiliation(s)
- Paula M Miotto
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph N1G 2W1, ON, Canada.
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph N1G 2W1, ON, Canada.
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31
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Miotto PM, McGlory C, Holloway TM, Phillips SM, Holloway GP. Sex differences in mitochondrial respiratory function in human skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2018. [PMID: 29513564 DOI: 10.1152/ajpregu.00025.2018] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mitochondrial bioenergetic contributions to sex differences in human skeletal muscle metabolism remain poorly defined. The primary aim of this study was to determine whether mitochondrial respiratory kinetics differed between healthy young men and women in permeabilized skeletal muscle fibers. While men and women displayed similar ( P > 0.05) maximal respiration rates and abundance of mitochondrial/adenosine diphosphate (ADP) transport proteins, women had lower ( P < 0.05) mitochondrial ADP sensitivity (+30% apparent Km) and absolute respiration rates at a physiologically relevant ADP concentration (100 μM). Moreover, although men and women exhibited similar carnitine palmitoyl transferase-I protein content- and palmitoyl-CoA-supported respiration, women displayed greater sensitivity to malonyl-CoA-mediated respiratory inhibition. These data establish baseline sex differences in mitochondrial bioenergetics and provide the foundation for studying mitochondrial function within the context of metabolic perturbations and diseases that affect men and women differently.
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Affiliation(s)
- Paula M Miotto
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Chris McGlory
- Department of Kinesiology, McMaster University , Hamilton, Ontario , Canada
| | - Tanya M Holloway
- Department of Kinesiology, McMaster University , Hamilton, Ontario , Canada
| | - Stuart M Phillips
- Department of Kinesiology, McMaster University , Hamilton, Ontario , Canada
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
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32
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Monaco CMF, Miotto PM, Huber JS, van Loon LJC, Simpson JA, Holloway GP. Sodium nitrate supplementation alters mitochondrial H 2O 2 emission but does not improve mitochondrial oxidative metabolism in the heart of healthy rats. Am J Physiol Regul Integr Comp Physiol 2018. [PMID: 29513565 DOI: 10.1152/ajpregu.00275.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Supplementation with dietary inorganic nitrate ([Formula: see text]) is increasingly recognized to confer cardioprotective effects in both healthy and clinical populations. While the mechanism(s) remains ambiguous, in skeletal muscle oral consumption of NaNO3 has been shown to improve mitochondrial efficiency. Whether NaNO3 has similar effects on mitochondria within the heart is unknown. Therefore, we comprehensively investigated the effect of NaNO3 supplementation on in vivo left ventricular (LV) function and mitochondrial bioenergetics. Healthy male Sprague-Dawley rats were supplemented with NaNO3 (1 g/l) in their drinking water for 7 days. Echocardiography and invasive hemodynamics were used to assess LV morphology and function. Blood pressure (BP) was measured by tail-cuff and invasive hemodynamics. Mitochondrial bioenergetics were measured in LV isolated mitochondria and permeabilized muscle fibers by high-resolution respirometry and fluorometry. Nitrate decreased ( P < 0.05) BP, LV end-diastolic pressure, and maximal LV pressure. Rates of LV relaxation (when normalized to mean arterial pressure) tended ( P = 0.13) to be higher with nitrate supplementation. However, nitrate did not alter LV mitochondrial respiration, coupling efficiency, or oxygen affinity in isolated mitochondria or permeabilized muscle fibers. In contrast, nitrate increased ( P < 0.05) the propensity for mitochondrial H2O2 emission in the absence of changes in cellular redox state and decreased the sensitivity of mitochondria to ADP (apparent Km). These results add to the therapeutic potential of nitrate supplementation in cardiovascular diseases and suggest that nitrate may confer these beneficial effects via mitochondrial redox signaling.
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Affiliation(s)
- Cynthia M F Monaco
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Paula M Miotto
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Jason S Huber
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Luc J C van Loon
- Department of Human Movement Sciences, Nutrition, and Toxicology, Research Institute Maastricht (NUTRIM), Maastricht University , Maastricht , The Netherlands
| | - Jeremy A Simpson
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada
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Trewin AJ, Levinger I, Parker L, Shaw CS, Serpiello FR, Anderson MJ, McConell GK, Hare DL, Stepto NK. Acute exercise alters skeletal muscle mitochondrial respiration and H2O2 emission in response to hyperinsulinemic-euglycemic clamp in middle-aged obese men. PLoS One 2017; 12:e0188421. [PMID: 29161316 PMCID: PMC5697830 DOI: 10.1371/journal.pone.0188421] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 11/07/2017] [Indexed: 12/16/2022] Open
Abstract
Obesity, sedentary lifestyle and aging are associated with mitochondrial dysfunction and impaired insulin sensitivity. Acute exercise increases insulin sensitivity in skeletal muscle; however, whether mitochondria are involved in these processes remains unclear. The aim of this study was to investigate the effects of insulin stimulation at rest and after acute exercise on skeletal muscle mitochondrial respiratory function (JO2) and hydrogen peroxide emission (JH2O2), and the associations with insulin sensitivity in obese, sedentary men. Nine men (means ± SD: 57 ± 6 years; BMI 33 ± 5 kg.m2) underwent hyperinsulinemic-euglycemic clamps in two separate trials 1–3 weeks apart: one under resting conditions, and another 1 hour after high-intensity exercise (4x4 min cycling at 95% HRpeak). Muscle biopsies were obtained at baseline, and pre/post clamp to measure JO2 with high-resolution respirometry and JH2O2 via Amplex UltraRed from permeabilized fibers. Post-exercise, both JO2 and JH2O2 during ADP stimulated state-3/OXPHOS respiration were lower compared to baseline (P<0.05), but not after subsequent insulin stimulation. JH2O2 was lower post-exercise and after subsequent insulin stimulation compared to insulin stimulation in the rest trial during succinate supported state-4/leak respiration (P<0.05). In contrast, JH2O2 increased during complex-I supported leak respiration with insulin after exercise compared with resting conditions (P<0.05). Resting insulin sensitivity and JH2O2 during complex-I leak respiration were positively correlated (r = 0.77, P<0.05). We conclude that in obese, older and sedentary men, acute exercise modifies skeletal muscle mitochondrial respiration and H2O2 emission responses to hyperinsulinemia in a respiratory state-specific manner, which may have implications for metabolic diseases involving insulin resistance.
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Affiliation(s)
- Adam J. Trewin
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Australia
| | - Itamar Levinger
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Australia
- Australian Institute for Musculoskeletal Science (AIMSS), Victoria University, St. Albans, Australia
| | - Lewan Parker
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Australia
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Christopher S. Shaw
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Australia
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Fabio R. Serpiello
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Australia
| | - Mitchell J. Anderson
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Australia
| | - Glenn K. McConell
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Australia
| | - David L. Hare
- University of Melbourne, and Department of Cardiology, Austin Health, Melbourne, Australia
| | - Nigel K. Stepto
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Australia
- Australian Institute for Musculoskeletal Science (AIMSS), Victoria University, St. Albans, Australia
- Monash Centre for Health Research and Implementation (MCHRI), Monash University and Monash Health, Clayton, Australia
- * E-mail:
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Whitfield J, Paglialunga S, Smith BK, Miotto PM, Simnett G, Robson HL, Jain SS, Herbst EAF, Desjardins EM, Dyck DJ, Spriet LL, Steinberg GR, Holloway GP. Ablating the protein TBC1D1 impairs contraction-induced sarcolemmal glucose transporter 4 redistribution but not insulin-mediated responses in rats. J Biol Chem 2017; 292:16653-16664. [PMID: 28808062 DOI: 10.1074/jbc.m117.806786] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/10/2017] [Indexed: 12/28/2022] Open
Abstract
TBC1 domain family member 1 (TBC1D1), a Rab GTPase-activating protein and paralogue of Akt substrate of 160 kDa (AS160), has been implicated in both insulin- and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase-mediated glucose transporter type 4 (GLUT4) translocation. However, the role of TBC1D1 in contracting muscle remains ambiguous. We therefore explored the metabolic consequence of ablating TBC1D1 in both resting and contracting skeletal muscles, utilizing a rat TBC1D1 KO model. Although insulin administration rapidly increased (p < 0.05) plasma membrane GLUT4 content in both red and white gastrocnemius muscles, the TBC1D1 ablation did not alter this response nor did it affect whole-body insulin tolerance, suggesting that TBC1D1 is not required for insulin-induced GLUT4 trafficking events. Consistent with findings in other models of altered TBC1D1 protein levels, whole-animal and ex vivo skeletal muscle fat oxidation was increased in the TBC1D1 KO rats. Although there was no change in mitochondrial content in the KO rats, maximal ADP-stimulated respiration was higher in permeabilized muscle fibers, which may contribute to the increased reliance on fatty acids in resting KO animals. Despite this increase in mitochondrial oxidative capacity, run time to exhaustion at various intensities was impaired in the KO rats. Moreover, contraction-induced increases in sarcolemmal GLUT4 content and glucose uptake were lower in the white gastrocnemius of the KO animals. Altogether, our results highlight a critical role for TBC1D1 in exercise tolerance and contraction-mediated translocation of GLUT4 to the plasma membrane in skeletal muscle.
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Affiliation(s)
- Jamie Whitfield
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
| | - Sabina Paglialunga
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
| | - Brennan K Smith
- Division of Endocrinology and Metabolism, Department of Medicine, and
| | - Paula M Miotto
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
| | - Genevieve Simnett
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
| | - Holly L Robson
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
| | - Swati S Jain
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
| | - Eric A F Herbst
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
| | - Eric M Desjardins
- Division of Endocrinology and Metabolism, Department of Medicine, and
| | - David J Dyck
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
| | - Lawrence L Spriet
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
| | - Gregory R Steinberg
- Division of Endocrinology and Metabolism, Department of Medicine, and.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - Graham P Holloway
- From the Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada and
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35
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Shannon CE, Ghasemi R, Greenhaff PL, Stephens FB. Increasing skeletal muscle carnitine availability does not alter the adaptations to high-intensity interval training. Scand J Med Sci Sports 2017; 28:107-115. [PMID: 28345160 DOI: 10.1111/sms.12885] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2017] [Indexed: 11/27/2022]
Abstract
Increasing skeletal muscle carnitine availability alters muscle metabolism during steady-state exercise in healthy humans. We investigated whether elevating muscle carnitine, and thereby the acetyl-group buffering capacity, altered the metabolic and physiological adaptations to 24 weeks of high-intensity interval training (HIIT) at 100% maximal exercise capacity (Wattmax ). Twenty-one healthy male volunteers (age 23±2 years; BMI 24.2±1.1 kg/m2 ) performed 2 × 3 minute bouts of cycling exercise at 100% Wattmax , separated by 5 minutes of rest. Fourteen volunteers repeated this protocol following 24 weeks of HIIT and twice-daily consumption of 80 g carbohydrate (CON) or 3 g l-carnitine+carbohydrate (CARN). Before HIIT, muscle phosphocreatine (PCr) degradation (P<.0001), glycogenolysis (P<.0005), PDC activation (P<.05), and acetylcarnitine (P<.005) were 2.3-, 2.1-, 1.5-, and 1.5-fold greater, respectively, in exercise bout two compared to bout 1, while lactate accumulation tended (P<.07) to be 1.5-fold greater. Following HIIT, muscle free carnitine was 30% greater in CARN vs CON at rest and remained 40% elevated prior to the start of bout 2 (P<.05). Following bout 2, free carnitine content, PCr degradation, glycogenolysis, lactate accumulation, and PDC activation were all similar between CON and CARN, albeit markedly lower than before HIIT. VO2max , Wattmax , and work output were similarly increased in CON and CARN, by 9, 15, and 23% (P<.001). In summary, increased reliance on non-mitochondrial ATP resynthesis during a second bout of intense exercise is accompanied by increased carnitine acetylation. Augmenting muscle carnitine during 24 weeks of HIIT did not alter this, nor did it enhance muscle metabolic adaptations or performance gains beyond those with HIIT alone.
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Affiliation(s)
- Christopher E Shannon
- MRC/ARUK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Nottingham, UK.,Diabetes Division, University of Texas Health Science Centre, San Antonio, TX, USA
| | - Reza Ghasemi
- MRC/ARUK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Paul L Greenhaff
- MRC/ARUK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Francis B Stephens
- MRC/ARUK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Nottingham, UK.,Sport and Health Sciences, University of Exeter, Exeter, UK
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36
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Controlling skeletal muscle CPT-I malonyl-CoA sensitivity: the importance of AMPK-independent regulation of intermediate filaments during exercise. Biochem J 2016; 474:557-569. [PMID: 27941154 DOI: 10.1042/bcj20160913] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/28/2016] [Accepted: 12/08/2016] [Indexed: 02/07/2023]
Abstract
The obligatory role of carnitine palmitoyltransferase-I (CPT-I) in mediating mitochondrial lipid transport is well established, a process attenuated by malonyl-CoA (M-CoA). However, the necessity of reducing M-CoA concentrations to promote lipid oxidation has recently been challenged, suggesting external regulation on CPT-I. Since previous work in hepatocytes suggests the involvement of the intermediate filament fraction of the cytoskeleton in regulating CPT-I, we investigated in skeletal muscle if CPT-I sensitivity for M-CoA inhibition could be regulated by the intermediate filaments, and whether AMP-activated protein kinase (AMPK) could be involved in this process. Chemical disruption (3,3'-iminodipropionitrile, IDPN) of the intermediate filaments did not alter mitochondrial respiration or sensitivity for numerous substrates (palmitoyl-CoA, ADP, palmitoyl carnitine and pyruvate). In contrast, IDPN reduced CPT-I sensitivity for M-CoA inhibition in permeabilized muscle fibers, identifying M-CoA kinetics as a specific target for intermediate filament regulation. Importantly, exercise mimicked the effect of IDPN on M-CoA sensitivity, suggesting that intermediate filament disruption in vivo is physiologically important for CPT-I regulation. To ascertain a potential mechanism, since AMPK is activated during exercise, AMPK β1β2-KO mice were utilized in an attempt to ablate the observed exercise response. Unexpectedly, these mice displayed drastic attenuation in resting M-CoA sensitivity, such that exercise and IDPN could not further alter M-CoA sensitivity. These data suggest that AMPK is not required for the regulation of the intermediate filament interaction with CPT-I. Altogether, these data highlight that M-CoA sensitivity is important for regulating mitochondrial lipid transport. Moreover, M-CoA sensitivity appears to be regulated by intermediate filament interaction with CPT-I, a process that is important when metabolic homeostasis is challenged.
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37
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Conley KE. Mitochondria to motion: optimizing oxidative phosphorylation to improve exercise performance. ACTA ACUST UNITED AC 2016; 219:243-9. [PMID: 26792336 DOI: 10.1242/jeb.126623] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mitochondria oxidize substrates to generate the ATP that fuels muscle contraction and locomotion. This review focuses on three steps in oxidative phosphorylation that have independent roles in setting the overall mitochondrial ATP flux and thereby have direct impact on locomotion. The first is the electron transport chain, which sets the pace for oxidation. New studies indicate that the electron transport chain capacity per mitochondria declines with age and disease, but can be revived by both acute and chronic treatments. The resulting higher ATP production is reflected in improved muscle power output and locomotory performance. The second step is the coupling of ATP supply from O2 uptake (mitochondrial coupling efficiency). Treatments that elevate mitochondrial coupling raise both exercise efficiency and the capacity for sustained exercise in both young and old muscle. The final step is ATP synthesis itself, which is under dynamic control at multiple sites to provide the 50-fold range of ATP flux between resting muscle and exercise at the mitochondrial capacity. Thus, malleability at sites in these subsystems of oxidative phosphorylation has an impact on ATP flux, with direct effects on exercise performance. Interventions are emerging that target these three independent subsystems to provide many paths to improve ATP flux and elevate the muscle performance lost to inactivity, age or disease.
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Affiliation(s)
- Kevin E Conley
- Departments of Radiology, Physiology & Biophysics, and Bioengineering, University of Washington Medical Center, Seattle, WA 98195, USA
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38
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In the absence of phosphate shuttling, exercise reveals the in vivo importance of creatine-independent mitochondrial ADP transport. Biochem J 2016; 473:2831-43. [PMID: 27402793 DOI: 10.1042/bcj20160373] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/08/2016] [Indexed: 12/28/2022]
Abstract
The transport of cytosolic adenosine diphosphate (ADP) into the mitochondria is a major control point in metabolic homeostasis, as ADP concentrations directly affect glycolytic flux and oxidative phosphorylation rates within mitochondria. A large contributor to the efficiency of this process is thought to involve phosphocreatine (PCr)/Creatine (Cr) shuttling through mitochondrial creatine kinase (Mi-CK), whereas the biological importance of alterations in Cr-independent ADP transport during exercise remains unknown. Therefore, we utilized an Mi-CK knockout (KO) model to determine whether in vivo Cr-independent mechanisms are biologically important for sustaining energy homeostasis during exercise. Ablating Mi-CK did not alter exercise tolerance, as the time to volitional fatigue was similar between wild-type (WT) and KO mice at various exercise intensities. In addition, skeletal muscle metabolic profiles after exercise, including glycogen, PCr/Cr ratios, free ADP/adenosine monophosphate (AMP), and lactate, were similar between genotypes. While these data suggest that the absence of PCr/Cr shuttling is not detrimental to maintaining energy homeostasis during exercise, KO mice displayed a dramatic increase in Cr-independent mitochondrial ADP sensitivity after exercise. Specifically, whereas mitochondrial ADP sensitivity decreased with exercise in WT mice, in stark contrast, exercise increased mitochondrial Cr-independent ADP sensitivity in KO mice. As a result, the apparent ADP Km was 50% lower in KO mice after exercise, suggesting that in vivo activation of voltage-dependent anion channel (VDAC)/adenine nucleotide translocase (ANT) can support mitochondrial ADP transport. Altogether, we provide insight that Cr-independent ADP transport mechanisms are biologically important for regulating ADP sensitivity during exercise, while highlighting complex regulation and the plasticity of the VDAC/ANT axis to support adenosine triphosphate demand.
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39
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Campbell MD, Marcinek DJ. Evaluation of in vivo mitochondrial bioenergetics in skeletal muscle using NMR and optical methods. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1862:716-724. [PMID: 26708941 PMCID: PMC4788529 DOI: 10.1016/j.bbadis.2015.12.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/20/2015] [Accepted: 12/16/2015] [Indexed: 12/13/2022]
Abstract
It is now clear that mitochondria are involved as either a cause or consequence of many chronic diseases. This central role of the mitochondria is due to their position in the cell as important integrators of cellular energetics and signaling. Mitochondrial function affects many aspects of the cellular environment such as redox homeostasis and calcium signaling, which then also exert control over mitochondrial function. This complex dynamic between mitochondrial function and the cellular environment highlights the value of examining mitochondria in vivo in the intact physiological environment. This review discusses NMR and optical approaches used to measure mitochondria ATP and oxygen fluxes that provide in vivo measures of mitochondrial capacity and quality in animal and human models. Combining these in vivo measurements with more traditional ex vivo analyses can lead to new insights into the importance of the cellular environment in controlling mitochondrial function under pathological conditions. Interpretation and underlying assumptions for each technique are discussed with the goal of providing an overview of some of the most common approaches used to measure in vivo mitochondrial function encountered in the literature.
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Affiliation(s)
- Matthew D Campbell
- University of Washington, Seattle, 850 Republican St., Brotman D142, Seattle, WA 98109, USA.
| | - David J Marcinek
- University of Washington, Seattle, 850 Republican St., Brotman D142, Seattle, WA 98109, USA.
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40
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Ydfors M, Hughes MC, Laham R, Schlattner U, Norrbom J, Perry CGR. Modelling in vivo creatine/phosphocreatine in vitro reveals divergent adaptations in human muscle mitochondrial respiratory control by ADP after acute and chronic exercise. J Physiol 2016; 594:3127-40. [PMID: 26631938 DOI: 10.1113/jp271259] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/19/2015] [Indexed: 01/14/2023] Open
Abstract
KEY POINTS Mitochondrial respiratory sensitivity to ADP is thought to influence muscle fitness and is partly regulated by cytosolic-mitochondrial diffusion of ADP or phosphate shuttling via creatine/phosphocreatine (Cr/PCr) through mitochondrial creatine kinase (mtCK). Previous measurements of respiration in vitro with Cr (saturate mtCK) or without (ADP/ATP diffusion) show mixed responses of ADP sensitivity following acute exercise vs. less sensitivity after chronic exercise. In human muscle, modelling in vivo 'exercising' [Cr:PCr] during in vitro assessments revealed novel responses to exercise that differ from detections with or without Cr (±Cr). Acute exercise increased ADP sensitivity when measured without Cr but had no effect ±Cr or with +Cr:PCr, whereas chronic exercise increased sensitivity ±Cr but lowered sensitivity with +Cr:PCr despite increased markers of mitochondrial oxidative capacity. Controlling in vivo conditions during in vitro respiratory assessments reveals responses to exercise that differ from typical ±Cr comparisons and challenges our understanding of how exercise improves metabolic control in human muscle. ABSTRACT Mitochondrial respiratory control by ADP (Kmapp ) is viewed as a critical regulator of muscle energy homeostasis. However, acute exercise increases, decreases or has no effect on Kmapp in human muscle, whereas chronic exercise surprisingly decreases sensitivity despite greater mitochondrial content. We hypothesized that modelling in vivo mitochondrial creatine kinase (mtCK)-dependent phosphate-shuttling conditions in vitro would reveal increased sensitivity (lower Kmapp ) after acute and chronic exercise. The Kmapp was determined in vitro with 20 mm Cr (+Cr), 0 mm Cr (-Cr) or 'in vivo exercising' 20 mm Cr/2.4 mm PCr (Cr:PCr) on vastus lateralis biopsies sampled from 11 men before, immediately after and 3 h after exercise on the first, fifth and ninth sessions over 3 weeks. Dynamic responses to acute exercise occurred throughout training, whereby the first session did not change Kmapp with in vivo Cr:PCr despite increases in -Cr. The fifth session decreased sensitivity with Cr:PCr or +Cr despite no change in -Cr. Chronic exercise increased sensitivity ±Cr in association with increased electron transport chain content (+33-62% complexes I-V), supporting classic proposals that link increased sensitivity to oxidative capacity. However, in vivo Cr:PCr reveals a perplexing decreased sensitivity, contrasting the increases seen ±Cr. Functional responses occurred without changes in fibre type or proteins regulating mitochondrial-cytosolic energy exchange (mtCK, VDAC and ANT). Despite the dynamic responses seen with ±Cr, modelling in vivo phosphate-shuttling conditions in vitro reveals that ADP sensitivity is unchanged after high-intensity exercise and is decreased after training. These findings challenge our understanding of how exercise regulates skeletal muscle energy homeostasis.
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Affiliation(s)
- Mia Ydfors
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Meghan C Hughes
- School of Kinesiology and Health Science, York University, Toronto, ON, Canada.,Muscle Health Research Centre, York University, Toronto, ON, Canada
| | - Robert Laham
- Muscle Health Research Centre, York University, Toronto, ON, Canada
| | - Uwe Schlattner
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy), University Grenoble Alpes, Grenoble, France
| | - Jessica Norrbom
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Christopher G R Perry
- School of Kinesiology and Health Science, York University, Toronto, ON, Canada.,Muscle Health Research Centre, York University, Toronto, ON, Canada
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41
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Søndergård SD, Dela F, Helge JW, Larsen S. Actovegin, a non-prohibited drug increases oxidative capacity in human skeletal muscle. Eur J Sport Sci 2016; 16:801-7. [PMID: 26744809 DOI: 10.1080/17461391.2015.1130750] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
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 system 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.
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Affiliation(s)
- Stine D Søndergård
- a Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Flemming Dela
- a Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Jørn W Helge
- a Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Steen Larsen
- a Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences , University of Copenhagen , Copenhagen , Denmark
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42
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Hughes MC, Ramos SV, Turnbull PC, Nejatbakhsh A, Baechler BL, Tahmasebi H, Laham R, Gurd BJ, Quadrilatero J, Kane DA, Perry CGR. Mitochondrial Bioenergetics and Fiber Type Assessments in Microbiopsy vs. Bergstrom Percutaneous Sampling of Human Skeletal Muscle. Front Physiol 2015; 6:360. [PMID: 26733870 PMCID: PMC4683189 DOI: 10.3389/fphys.2015.00360] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/16/2015] [Indexed: 01/22/2023] Open
Abstract
Microbiopsies of human skeletal muscle are increasingly adopted by physiologists for a variety of experimental assays given the reduced invasiveness of this procedure compared to the classic Bergstrom percutaneous biopsy technique. However, a recent report demonstrated lower mitochondrial respiration in saponin-permeabilized muscle fiber bundles (PmFB) prepared from microbiopsies vs. Bergstrom biopsies. We hypothesized that ADP-induced contraction (rigor) of smaller length microbiopsy PmFB causes a greater reduction in maximal respiration vs. Bergstrom, such that respiration could be increased by a myosin II ATPase-inhibitor (Blebbistatin; BLEB). Eleven males and females each received a 2 mm diameter percutaneous microbiopsy and a 5 mm diameter Bergstrom percutaneous biopsy in opposite legs. Glutamate/malate (5/0.5 mM)—supported respiration in microbiopsy PmFB was lower than Bergstrom at submaximal concentrations of ADP. 5 μM BLEB reduced this impairment such that there were no differences relative to Bergstrom ± BLEB. Surprisingly, pyruvate (5 mM)-supported respiration was not different between either biopsy technique ±BLEB, whereas BLEB increased succinate-supported respiration in Bergstrom only. H2O2 emission was lower in microbiopsy PmFB compared to Bergstrom PmFB in the presence of BLEB. Microbiopsies contained fewer type I fibers (37 vs. 47%) and more type IIX fibers (20 vs. 8%) compared to Bergstrom possibly due to sampling site depth and/or longitudinal location. These findings suggest that smaller diameter percutaneous biopsies yield lower glutamate-supported mitochondrial respiratory kinetics which is increased by preventing ADP-induced rigor with myosin inhibition. Microbiopsies of human skeletal muscle can be utilized for assessing mitochondrial respiratory kinetics in PmFB when assay conditions are supplemented with BLEB, but fiber type differences with this method should be considered.
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Affiliation(s)
- Meghan C Hughes
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University Toronto, ON, Canada
| | - Sofhia V Ramos
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University Toronto, ON, Canada
| | - Patrick C Turnbull
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University Toronto, ON, Canada
| | - Ali Nejatbakhsh
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University Toronto, ON, Canada
| | | | - Houman Tahmasebi
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University Toronto, ON, Canada
| | - Robert Laham
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University Toronto, ON, Canada
| | - Brendon J Gurd
- School of Kinesiology and Health Studies, Queen's University Kingston, ON, Canada
| | - Joe Quadrilatero
- Department of Kinesiology, University of Waterloo Waterloo, ON, Canada
| | - Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University Antigonish, NS, Canada
| | - Christopher G R Perry
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University Toronto, ON, Canada
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43
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Whitfield J, Ludzki A, Heigenhauser GJF, Senden JMG, Verdijk LB, van Loon LJC, Spriet LL, Holloway GP. Beetroot juice supplementation reduces whole body oxygen consumption but does not improve indices of mitochondrial efficiency in human skeletal muscle. J Physiol 2015; 594:421-35. [PMID: 26457670 DOI: 10.1113/jp270844] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 09/29/2015] [Indexed: 12/23/2022] Open
Abstract
KEY POINTS Oral consumption of nitrate (NO3(-)) in beetroot juice has been shown to decrease the oxygen cost of submaximal exercise; however, the mechanism of action remains unresolved. We supplemented recreationally active males with beetroot juice to determine if this altered mitochondrial bioenergetics. Despite reduced submaximal exercise oxygen consumption, measures of mitochondrial coupling and respiratory efficiency were not altered in muscle. In contrast, rates of mitochondrial hydrogen peroxide (H2O2) emission were increased in the absence of markers of lipid or protein oxidative damage. These results suggest that improvements in mitochondrial oxidative metabolism are not the cause of beetroot juice-mediated improvements in whole body oxygen consumption. ABSTRACT Ingestion of sodium nitrate (NO3(-)) simultaneously reduces whole body oxygen consumption (V̇O2) during submaximal exercise while improving mitochondrial efficiency, suggesting a causal link. Consumption of beetroot juice (BRJ) elicits similar decreases in V̇O2 but potential effects on the mitochondria remain unknown. Therefore we examined the effects of 7-day supplementation with BRJ (280 ml day(-1), ∼26 mmol NO3(-)) in young active males (n = 10) who had muscle biopsies taken before and after supplementation for assessments of mitochondrial bioenergetics. Subjects performed 20 min of cycling (10 min at 50% and 70% V̇O2 peak) 48 h before 'Pre' (baseline) and 'Post' (day 5 of supplementation) biopsies. Whole body V̇O2 decreased (P < 0.05) by ∼3% at 70% V̇O2 peak following supplementation. Mitochondrial respiration in permeabilized muscle fibres showed no change in leak respiration, the content of proteins associated with uncoupling (UCP3, ANT1, ANT2), maximal substrate-supported respiration, or ADP sensitivity (apparent Km). In addition, isolated subsarcolemmal and intermyofibrillar mitochondria showed unaltered assessments of mitochondrial efficiency, including ADP consumed/oxygen consumed (P/O ratio), respiratory control ratios and membrane potential determined fluorometrically using Safranine-O. In contrast, rates of mitochondrial hydrogen peroxide (H2O2) emission were increased following BRJ. Therefore, in contrast to sodium nitrate, BRJ supplementation does not alter key parameters of mitochondrial efficiency. This occurred despite a decrease in exercise V̇O2, suggesting that the ergogenic effects of BRJ ingestion are not due to a change in mitochondrial coupling or efficiency. It remains to be determined if increased mitochondrial H2O2 contributes to this response.
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Affiliation(s)
- J Whitfield
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - A Ludzki
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - G J F Heigenhauser
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada, L8N 3Z5
| | - J M G Senden
- Department of Human Movement Sciences, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, 6200 MD, Maastricht, The Netherlands
| | - L B Verdijk
- Department of Human Movement Sciences, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, 6200 MD, Maastricht, The Netherlands
| | - L J C van Loon
- Department of Human Movement Sciences, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, 6200 MD, Maastricht, The Netherlands
| | - L L Spriet
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - G P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
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44
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Herbst EAF, Roussakis C, Matravadia S, Holloway GP. Chronic treadmill running does not enhance mitochondrial oxidative capacity in the cortex or striatum. Metabolism 2015; 64:1419-25. [PMID: 26307661 DOI: 10.1016/j.metabol.2015.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 06/17/2015] [Accepted: 07/02/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVE The aims of the present study were to determine in healthy animals if 1) acute exercise stimulated traditional exercise signaling pathways in the cortex and striatum, and 2) if chronic exercise training increased the oxidative capacity of these brain regions. METHODS Male C57BL/6 mice were left sedentary, acutely exercised for 15 or 60 min to examine potential signaling cascades activated by exercise, or chronically exercise for 4 wk to examine the impact of prolonged training. The cortex and striatum were analyzed for changes in the phosphorylation of AMPK, CAMKII, ERK1/2, and P38 with acute exercise, or markers of mitochondrial protein content, mtDNA copy number, and mitochondrial respiration with chronic exercise. RESULTS In mice, acute treadmill running did not alter the phosphorylation of AMPK, CAMKII, or P38 in either the cortex or the striatum, but decreased ERK1/2 phosphorylation in only the cortex for the duration of the exercise bout. Following chronic exercise training, mitochondrial respiration, mtDNA copy number, and protein content of various subunits of the electron transport chain were not altered in adult mice. CONCLUSION Combined, these data suggest that exercise does not result in increased phosphorylation of traditional signaling kinases or enhanced mitochondrial oxidative capacity in either the cortex or the striatum of healthy animals.
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Affiliation(s)
- Eric A F Herbst
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
| | - Christina Roussakis
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Sarthak Matravadia
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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Ludzki A, Paglialunga S, Smith BK, Herbst EAF, Allison MK, Heigenhauser GJ, Neufer PD, Holloway GP. Rapid Repression of ADP Transport by Palmitoyl-CoA Is Attenuated by Exercise Training in Humans: A Potential Mechanism to Decrease Oxidative Stress and Improve Skeletal Muscle Insulin Signaling. Diabetes 2015; 64:2769-79. [PMID: 25845660 PMCID: PMC4876790 DOI: 10.2337/db14-1838] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/28/2015] [Indexed: 12/11/2022]
Abstract
Mitochondrial ADP transport may represent a convergence point unifying two prominent working models for the development of insulin resistance, as reactive lipids (specifically palmitoyl-CoA [P-CoA]) can inhibit ADP transport and subsequently increase mitochondrial reactive oxygen species emissions. In the current study, we aimed to determine if exercise training in humans diminished P-CoA attenuation of mitochondrial ADP respiratory sensitivity. Six weeks of exercise training increased whole-body glucose homeostasis and skeletal muscle Akt signaling and reduced markers of oxidative stress without reducing maximal mitochondrial H2O2 emissions. To ascertain if enhanced mitochondrial ADP transport contributed to the improvement in the in vivo oxidative state, we determined mitochondrial ADP sensitivity in the presence and absence of P-CoA. In the absence of P-CoA, exercise training reduced mitochondrial ADP sensitivity. In contrast, exercise training increased mitochondrial ADP sensitivity with P-CoA present. We further show that P-CoA noncompetitively inhibits mitochondrial ADP transport and the ability of ADP to attenuate mitochondrial H2O2 emission. Altogether, the current data provide a potential mechanism for how P-CoA contributes to insulin resistance and highlight the ability of exercise training to diminish P-CoA attenuation in mitochondrial ADP transport.
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Affiliation(s)
- Alison Ludzki
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Sabina Paglialunga
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Brennan K Smith
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Eric A F Herbst
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Mary K Allison
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | | | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - Graham P Holloway
- Department of Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Kemp GJ, Ahmad RE, Nicolay K, Prompers JJ. Quantification of skeletal muscle mitochondrial function by 31P magnetic resonance spectroscopy techniques: a quantitative review. Acta Physiol (Oxf) 2015; 213:107-44. [PMID: 24773619 DOI: 10.1111/apha.12307] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 12/30/2013] [Accepted: 04/23/2014] [Indexed: 12/16/2022]
Abstract
Magnetic resonance spectroscopy (MRS) can give information about cellular metabolism in vivo which is difficult to obtain in other ways. In skeletal muscle, non-invasive (31) P MRS measurements of the post-exercise recovery kinetics of pH, [PCr], [Pi] and [ADP] contain valuable information about muscle mitochondrial function and cellular pH homeostasis in vivo, but quantitative interpretation depends on understanding the underlying physiology. Here, by giving examples of the analysis of (31) P MRS recovery data, by some simple computational simulation, and by extensively comparing data from published studies using both (31) P MRS and invasive direct measurements of muscle O2 consumption in a common analytical framework, we consider what can be learnt quantitatively about mitochondrial metabolism in skeletal muscle using MRS-based methodology. We explore some technical and conceptual limitations of current methods, and point out some aspects of the physiology which are still incompletely understood.
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Affiliation(s)
- G. J. Kemp
- Department of Musculoskeletal Biology, and Magnetic Resonance and Image Analysis Research Centre; University of Liverpool; Liverpool UK
| | - R. E. Ahmad
- Department of Musculoskeletal Biology, and Magnetic Resonance and Image Analysis Research Centre; University of Liverpool; Liverpool UK
| | - K. Nicolay
- Biomedical NMR; Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven the Netherlands
| | - J. J. Prompers
- Biomedical NMR; Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven the Netherlands
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47
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Hearts of some Antarctic fishes lack mitochondrial creatine kinase. Comp Biochem Physiol A Mol Integr Physiol 2014; 178:30-6. [PMID: 25151023 DOI: 10.1016/j.cbpa.2014.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Revised: 08/12/2014] [Accepted: 08/13/2014] [Indexed: 11/23/2022]
Abstract
Creatine kinase (CK; EC 2.7.3.2) functions as a spatial and temporal energy buffer, dampening fluctuations in ATP levels as ATP supply and demand change. There are four CK isoforms in mammals, two cytosolic isoforms (muscle [M-CK] and brain [B-CK]), and two mitochondrial isoforms (ubiquitous [uMtCK] and sarcomeric [sMtCK]). Mammalian oxidative muscle couples expression of sMtCK with M-CK, creating an energy shuttle between mitochondria and myofibrils. We hypothesized that the expression pattern and activity of CK would differ between hearts of red- and white-blooded Antarctic notothenioid fishes due to their striking differences in cardiac ultrastructure. Hearts of white-blooded icefishes (family Channichthyidae) have significantly higher mitochondrial densities compared to red-blooded species, decreasing the diffusion distance for ATP between mitochondria and myofibrils and potentially minimizing the need for CK. The distribution of CK isoforms was evaluated using western blotting and maximal activity of CK was measured in mitochondrial and cytosolic fractions and tissue homogenates of heart ventricles of red- and white-blooded notothenioids. Transcript abundance of sMtCK and M-CK was also quantified. Overall, CK activity is similar between hearts of red- and white-blooded notothenioids but hearts of icefishes lack MtCK and have higher activities of M-CK in the cytosol compared to red-blooded fishes. The absence of MtCK may compromise cardiac function under stressful conditions when ATP supply becomes limiting.
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Beaudoin MS, Perry CGR, Arkell AM, Chabowski A, Simpson JA, Wright DC, Holloway GP. Impairments in mitochondrial palmitoyl-CoA respiratory kinetics that precede development of diabetic cardiomyopathy are prevented by resveratrol in ZDF rats. J Physiol 2014; 592:2519-33. [PMID: 24639481 DOI: 10.1113/jphysiol.2013.270538] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Alterations in lipid metabolism within the heart may have a causal role in the establishment of diabetic cardiomyopathy; however, this remains equivocal. Therefore, in the current study we determined cardiac mitochondrial bioenergetics in ZDF rats before overt type 2 diabetes and diabetic cardiomyopathy developed. In addition, we utilized resveratrol, a compound previously shown to improve, prevent or reverse cardiac dysfunction in high-fat-fed rodents, as a tool to potentially recover dysfunctions within mitochondria. Fasting blood glucose and invasive left ventricular haemodynamic analysis confirmed the absence of type 2 diabetes and diabetic cardiomyopathy. However, fibrosis was already increased (P < 0.05) ∼70% in ZDF rats at this early stage in disease progression. Assessments of mitochondrial ADP and pyruvate respiratory kinetics in permeabilized fibres from the left ventricle revealed normal electron transport chain function and content. In contrast, the apparent Km to palmitoyl-CoA (P-CoA) was increased (P < 0.05) ∼60%, which was associated with an accumulation of intracellular triacylgycerol, diacylglycerol and ceramide species. In addition, the capacity for mitochondrial reactive oxygen species emission was increased (P < 0.05) ∼3-fold in ZDF rats. The provision of resveratrol reduced fibrosis, P-CoA respiratory sensitivity, reactive lipid accumulation and mitochondrial reactive oxygen species emission rates. Altogether the current data support the supposition that a chronic dysfunction within mitochondrial lipid-supported bioenergetics contributes to the development of diabetic cardiomyopathy, as this was present before overt diabetes or cardiac dysfunction. In addition, we show that resveratrol supplementation prevents these changes, supporting the belief that resveratrol is a potent therapeutic approach for preventing diabetic cardiomyopathy.
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Affiliation(s)
- Marie-Soleil Beaudoin
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada, N1G 2W1
| | - Christopher G R Perry
- School of Kinesiology and Health Science, Faculty of Health, York University, Toronto, Ontario, Canada, M3J 1P3
| | - Alicia M Arkell
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada, N1G 2W1
| | - Adrian Chabowski
- Department of Physiology, Medical University of Bialystok, 15-222 Bialystok, Poland
| | - Jeremy A Simpson
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada, N1G 2W1
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada, N1G 2W1
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada, N1G 2W1
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Herbst EAF, Paglialunga S, Gerling C, Whitfield J, Mukai K, Chabowski A, Heigenhauser GJF, Spriet LL, Holloway GP. Omega-3 supplementation alters mitochondrial membrane composition and respiration kinetics in human skeletal muscle. J Physiol 2014; 592:1341-52. [PMID: 24396061 DOI: 10.1113/jphysiol.2013.267336] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Studies have shown increased incorporation of omega-3 fatty acids into whole skeletal muscle following supplementation, although little has been done to investigate the potential impact on the fatty acid composition of mitochondrial membranes and the functional consequences on mitochondrial bioenergetics. Therefore, we supplemented young healthy male subjects (n = 18) with fish oils [2 g eicosapentaenoic acid (EPA) and 1 g docosahexanoic acid (DHA) per day] for 12 weeks and skeletal muscle biopsies were taken prior to (Pre) and following (Post) supplementation for the analysis of mitochondrial membrane phospholipid composition and various assessments of mitochondrial bioenergetics. Total EPA and DHA content in mitochondrial membranes increased (P < 0.05) ∼450 and ∼320%, respectively, and displaced some omega-6 species in several phospholipid populations. Mitochondrial respiration, determined in permeabilized muscle fibres, demonstrated no change in maximal substrate-supported respiration, or in the sensitivity (apparent Km) and maximal capacity for pyruvate-supported respiration. In contrast, mitochondrial responses during ADP titrations demonstrated an enhanced ADP sensitivity (decreased apparent Km) that was independent of the creatine kinase shuttle. As the content of ANT1, ANT2, and subunits of the electron transport chain were unaltered by supplementation, these data suggest that prolonged omega-3 intake improves ADP kinetics in human skeletal muscle mitochondria through alterations in membrane structure and/or post-translational modification of ATP synthase and ANT isoforms. Omega-3 supplementation also increased the capacity for mitochondrial reactive oxygen species emission without altering the content of oxidative products, suggesting the absence of oxidative damage. The current data strongly emphasize a role for omega-3s in reorganizing the composition of mitochondrial membranes while promoting improvements in ADP sensitivity.
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Affiliation(s)
- E A F Herbst
- Human Health and Nutritional Sciences, University of Guelph, 491 Gordon St., Guelph, ON N1G 2W1, Canada.
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Smith BK, Perry CGR, Herbst EAF, Ritchie IR, Beaudoin MS, Smith JC, Neufer PD, Wright DC, Holloway GP. Submaximal ADP-stimulated respiration is impaired in ZDF rats and recovered by resveratrol. J Physiol 2013; 591:6089-101. [PMID: 24081154 DOI: 10.1113/jphysiol.2013.259226] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mitochondrial dysfunction and reactive oxygen species (ROS) have been implicated in the aetiology of skeletal muscle insulin resistance, although there is considerable controversy regarding these concepts. Mitochondrial function has been traditionally assessed in the presence of saturating ADP, but ATP turnover and the resultant ADP is thought to limit respiration in vivo. Therefore, we investigated the potential link between submaximal ADP-stimulated respiration rates, ROS generation and skeletal muscle insulin sensitivity in a model of type 2 diabetes mellitus, the ZDF rat. Utilizing permeabilized muscle fibres we observed that submaximal ADP-stimulated respiration rates (250-2000 μm ADP) were lower in ZDF rats than in lean controls, which coincided with decreased adenine nucleotide translocase 2 (ANT2) protein content. This decrease in submaximal ADP-stimulated respiration occurred in the absence of a decrease in electron transport chain function. Treating ZDF rats with resveratrol improved skeletal muscle insulin resistance and this was associated with elevated submaximal ADP-stimulated respiration rates as well as an increase in ANT2 protein content. These results coincided with a greater ability of ADP to attenuate mitochondrial ROS emission and an improvement in cellular redox balance. Together, these data suggest that mitochondrial dysfunction is present in skeletal muscle insulin resistance when assessed at submaximal ADP concentrations and that ADP dynamics may influence skeletal muscle insulin sensitivity through alterations in the propensity for mitochondrial ROS emission.
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Affiliation(s)
- Brennan K Smith
- G. P. Holloway: Human Health and Nutritional Sciences, University of Guelph, 491 Gordon St., Guelph, ON, Canada, N1G 2W1.
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