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Popov DV, Lysenko EA, Kuzmin IV, Vinogradova V, Grigoriev AI. Regulation of PGC-1α Isoform Expression in Skeletal Muscles. Acta Naturae 2015; 7:48-59. [PMID: 25927001 PMCID: PMC4410395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The coactivator PGC-1α is the key regulator of mitochondrial biogenesis in skeletal muscle. Skeletal muscle expresses several PGC-1α isoforms. This review covers the functional role of PGC-1α isoforms and the regulation of their exercise-associated expression in skeletal muscle. The patterns of PGC-1α mRNA expression may markedly differ at rest and after muscle activity. Different signaling pathways are activated by different physiological stimuli, which regulate the expression of the PGC-1α gene from the canonical and alternative promoters: expression from a canonical (proximal) promoter is regulated by activation of the AMPK; expression from an alternative promoter, via a β2-adrenergic receptor. All transcripts from both promoters are subject to alternative splicing. As a result, truncated isoforms that possess different properties are translated: truncated isoforms are more stable and predominantly activate angiogenesis, whereas full-length isoforms manly regulate mitochondrial biogenesis. The existence of several isoforms partially explains the broad-spectrum function of this protein and allows the organism to adapt to different physiological stimuli. Regulation of the PGC-1α gene expression by different signaling pathways provides ample opportunity for pharmacological influence on the expression of this gene. Those opportunities might be important for the treatment and prevention of various diseases, such as metabolic syndrome and diabetes mellitus. Elucidation of the regulatory mechanisms of the PGC-1α gene expression and their functional role may provide an opportunity to control the expression of different isoforms through exercise and/or pharmacological intervention.
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Affiliation(s)
- D. V. Popov
- Institute of Biomedical problems, Russian Academy of Sciences, Khoroshevskoye shosse, 76A, Moscow, 123007, Russia,Faculty of Fundamental Medicine, M.V. Lomonosov Moscow State University, Lomonosovskiy prospect, 26B–10, Moscow, 119192, Russia
| | - E. A. Lysenko
- Institute of Biomedical problems, Russian Academy of Sciences, Khoroshevskoye shosse, 76A, Moscow, 123007, Russia
| | - I. V. Kuzmin
- Institute of Biomedical problems, Russian Academy of Sciences, Khoroshevskoye shosse, 76A, Moscow, 123007, Russia,Department of Genetics, Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory, 1–12, Moscow, 119991, Russia
| | - Vinogradova Vinogradova
- Institute of Biomedical problems, Russian Academy of Sciences, Khoroshevskoye shosse, 76A, Moscow, 123007, Russia,Faculty of Fundamental Medicine, M.V. Lomonosov Moscow State University, Lomonosovskiy prospect, 26B–10, Moscow, 119192, Russia
| | - A. I. Grigoriev
- Institute of Biomedical problems, Russian Academy of Sciences, Khoroshevskoye shosse, 76A, Moscow, 123007, Russia,Faculty of Fundamental Medicine, M.V. Lomonosov Moscow State University, Lomonosovskiy prospect, 26B–10, Moscow, 119192, Russia
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Psilander N, Frank P, Flockhart M, Sahlin K. Adding strength to endurance training does not enhance aerobic capacity in cyclists. Scand J Med Sci Sports 2014; 25:e353-9. [DOI: 10.1111/sms.12338] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2014] [Indexed: 11/28/2022]
Affiliation(s)
- N. Psilander
- Åstrand Laboratory; GIH; The Swedish School of Sport and Health Sciences; Stockholm Sweden
- Department of Physiology and Pharmacology; Karolinska Institutet; Stockholm Sweden
| | - P. Frank
- Åstrand Laboratory; GIH; The Swedish School of Sport and Health Sciences; Stockholm Sweden
- Department of Physiology and Pharmacology; Karolinska Institutet; Stockholm Sweden
| | - M. Flockhart
- Åstrand Laboratory; GIH; The Swedish School of Sport and Health Sciences; Stockholm Sweden
| | - K. Sahlin
- Åstrand Laboratory; GIH; The Swedish School of Sport and Health Sciences; Stockholm Sweden
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53
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Jun HJ, Joshi Y, Patil Y, Noland RC, Chang JS. NT-PGC-1α activation attenuates high-fat diet-induced obesity by enhancing brown fat thermogenesis and adipose tissue oxidative metabolism. Diabetes 2014; 63:3615-25. [PMID: 24848065 PMCID: PMC4207386 DOI: 10.2337/db13-1837] [Citation(s) in RCA: 29] [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: 12/03/2013] [Accepted: 05/16/2014] [Indexed: 11/13/2022]
Abstract
The transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator (PGC)-1α and its splice variant N terminal (NT)-PGC-1α regulate adaptive thermogenesis by transcriptional induction of thermogenic and mitochondrial genes involved in energy metabolism. We previously reported that full-length PGC-1α (FL-PGC-1α) is dispensable for cold-induced nonshivering thermogenesis in FL-PGC-1α(-/-) mice, since a slightly shorter but functionally equivalent form of NT-PGC-1α (NT-PGC-1α(254)) fully compensates for the loss of FL-PGC-1α in brown and white adipose tissue. In the current study, we challenged FL-PGC-1α(-/-) mice with a high-fat diet (HFD) to investigate the effects of diet-induced thermogenesis on HFD-induced obesity. Despite a large decrease in locomotor activity, FL-PGC-1α(-/-) mice exhibited the surprising ability to attenuate HFD-induced obesity. Reduced fat mass in FL-PGC-1α(-/-) mice was closely associated with an increase in body temperature, energy expenditure, and whole-body fatty acid oxidation (FAO). Mechanistically, FL-PGC-1α(-/-) brown adipose tissue had an increased capacity to oxidize fatty acids and dissipate energy as heat, in accordance with upregulation of thermogenic genes UCP1 and DIO2. Furthermore, augmented expression of FAO and lipolytic genes in FL-PGC-1α(-/-) white adipose tissue was highly correlated with decreased fat storage in adipose tissue. Collectively, our data highlight a protective effect of NT-PGC-1α on diet-induced obesity by enhancing diet-induced thermogenesis and FAO.
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Affiliation(s)
- Hee-Jin Jun
- Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, LA
| | - Yagini Joshi
- Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, LA
| | - Yuvraj Patil
- Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, LA
| | - Robert C Noland
- Laboratory of Skeletal Muscle Metabolism, Pennington Biomedical Research Center, Baton Rouge, LA
| | - Ji Suk Chang
- Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, LA
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MacNeil LG, Glover E, Bergstra TG, Safdar A, Tarnopolsky MA. The order of exercise during concurrent training for rehabilitation does not alter acute genetic expression, mitochondrial enzyme activity or improvements in muscle function. PLoS One 2014; 9:e109189. [PMID: 25289940 PMCID: PMC4188604 DOI: 10.1371/journal.pone.0109189] [Citation(s) in RCA: 20] [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: 03/31/2014] [Accepted: 09/08/2014] [Indexed: 01/09/2023] Open
Abstract
Concurrent exercise combines different modes of exercise (e.g., aerobic and resistance) into one training protocol, providing stimuli meant to increase muscle strength, aerobic capacity and mass. As disuse is associated with decrements in strength, aerobic capacity and muscle size concurrent training is an attractive modality for rehabilitation. However, interference between the signaling pathways may result in preferential improvements for one of the exercise modes. We recruited 18 young adults (10 ♂, 8 ♀) to determine if order of exercise mode during concurrent training would differentially affect gene expression, protein content and measures of strength and aerobic capacity after 2 weeks of knee-brace induced disuse. Concurrent exercise sessions were performed 3x/week for 6 weeks at gradually increasing intensities either with endurance exercise preceding (END>RES) or following (RES>END) resistance exercise. Biopsies were collected from the vastus lateralis before, 3 h after the first exercise bout and 48 h after the end of training. Concurrent exercise altered the expression of genes involved in mitochondrial biogenesis (PGC-1α, PRC, PPARγ), hypertrophy (PGC-1α4, REDD2, Rheb) and atrophy (MuRF-1, Runx1), increased electron transport chain complex protein content, citrate synthase and mitochondrial cytochrome c oxidase enzyme activity, muscle mass, maximum isometric strength and VO2peak. However, the order in which exercise was completed (END>RES or RES>END) only affected the protein content of mitochondrial complex II subunit. In conclusion, concurrent exercise training is an effective modality for the rehabilitation of the loss of skeletal muscle mass, maximum strength, and peak aerobic capacity resulting from disuse, regardless of the order in which the modes of exercise are performed.
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Affiliation(s)
- Lauren G. MacNeil
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | - Elisa Glover
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | - T. Graham Bergstra
- Department of Health Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Adeel Safdar
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | - Mark A. Tarnopolsky
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
- * E-mail:
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Perry CGR. Is muscle hypertrophy following resistance exercise regulated by truncated splice variants of PGC-1α? Acta Physiol (Oxf) 2014; 212:122-4. [PMID: 25042237 DOI: 10.1111/apha.12348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- C. G. R. Perry
- School of Kinesiology & Health Science; Muscle Health Research Centre; York University; Toronto ON Canada
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Lundberg TR, Fernandez-Gonzalo R, Norrbom J, Fischer H, Tesch PA, Gustafsson T. Truncated splice variant PGC-1α4 is not associated with exercise-induced human muscle hypertrophy. Acta Physiol (Oxf) 2014; 212:142-51. [PMID: 24800995 DOI: 10.1111/apha.12310] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/23/2014] [Accepted: 04/28/2014] [Indexed: 12/18/2022]
Abstract
INTRODUCTION A truncated PGC-1α splice variant (PGC-1α4) has been implicated in the regulation of resistance exercise (RE)-induced muscle hypertrophy, and basal expression levels said to be augmented in response to concurrent aerobic (AE) and RE training. AIM The current study investigated human muscle truncated and non-truncated PGC-1α transcripts in response to both acute and chronic RE, and with or without preceding AE (AE+RE). METHODS Ten men performed 5 weeks of unilateral AE+RE and RE training. Before (untrained) and after (trained) this intervention, PGC-1α transcripts were assessed in vastus lateralis muscle biopsies obtained before and 3 h after acute RE, with or without preceding AE. Additionally, samples were collected 72 h after the last exercise bout of the training programme. RESULTS The truncated splice variant increased (P < 0.05) its expression after acute exercise regardless of mode. However, the expression was greater (P < 0.05) after AE+RE than RE. Other PGC-1α transcripts showed similar response. Truncated transcripts originated from both the alternative and proximal promoter, and AE+RE increased PGC-1α expression from both promoter sites. RE induced transcripts from the alternative promoter only. PGC-1α expressions after acute exercise were comparable across isoforms in both untrained and trained muscle. Steady-state levels of isoforms were unchanged after 5-week training (P > 0.05). Exercise-induced expression of PGC-1α variants did not correlate with changes in muscle size or strength (P > 0.05). CONCLUSION Our results do not support the view that truncated PGC-1α coordinates exercise-induced hypertrophy in human skeletal muscle. Rather, all PGC-1α isoforms appear to be regulated transiently in response to acute exercise and regardless of mode.
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Affiliation(s)
- T. R. Lundberg
- Department of Health Sciences; Mid Sweden University; Östersund Sweden
| | - R. Fernandez-Gonzalo
- Department of Physiology & Pharmacology; Karolinska Institutet; Stockholm Sweden
| | - J. Norrbom
- Department of Physiology & Pharmacology; Karolinska Institutet; Stockholm Sweden
| | - H. Fischer
- Department of Laboratory Medicine; Section for Clinical Physiology; Karolinska Institutet; Karolinska University Hospital; Stockholm Sweden
| | - P. A. Tesch
- Department of Physiology & Pharmacology; Karolinska Institutet; Stockholm Sweden
| | - T. Gustafsson
- Department of Laboratory Medicine; Section for Clinical Physiology; Karolinska Institutet; Karolinska University Hospital; Stockholm Sweden
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The relationship between muscle fiber type-specific PGC-1α content and mitochondrial content varies between rodent models and humans. PLoS One 2014; 9:e103044. [PMID: 25121500 PMCID: PMC4133187 DOI: 10.1371/journal.pone.0103044] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Accepted: 06/26/2014] [Indexed: 11/25/2022] Open
Abstract
PGC-1α regulates critical processes in muscle physiology, including mitochondrial biogenesis, lipid metabolism and angiogenesis. Furthermore, PGC-1α was suggested as an important regulator of fiber type determination. However, whether a muscle fiber type-specific PGC-1α content exists, whether PGC-1α content relates to basal levels of mitochondrial content, and whether such relationships are preserved between humans and classically used rodent models are all questions that have been either poorly addressed or never investigated. To address these issues, we investigated the fiber type-specific content of PGC-1α and its relationship to basal mitochondrial content in mouse, rat and human muscles using in situ immunolabeling and histochemical methods on muscle serial cross-sections. Whereas type IIa fibers exhibited the highest PGC-1α in all three species, other fiber types displayed a hierarchy of type IIx>I>IIb in mouse, type I = IIx> IIb in rat, and type IIx>I in human. In terms of mitochondrial content, we observed a hierarchy of IIa>IIx>I>IIb in mouse, IIa >I>IIx> IIb in rat, and I>IIa> IIx in human skeletal muscle. We also found in rat skeletal muscle that type I fibers displayed the highest capillarization followed by type IIa >IIx>IIb. Finally, we found in human skeletal muscle that type I fibers display the highest lipid content, followed by type IIa>IIx. Altogether, our results reveal that (i) the fiber type-specific PGC-1α and mitochondrial contents were only matched in mouse, (ii) the patterns of PGC-1α and mitochondrial contents observed in mice and rats do not correspond to that seen in humans in several respects, and (iii) the classical phenotypes thought to be regulated by PGC-1α do not vary exclusively as a function of PGC-1α content in rat and human muscles.
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Sanchez AMJ, Bernardi H, Py G, Candau RB. Autophagy is essential to support skeletal muscle plasticity in response to endurance exercise. Am J Physiol Regul Integr Comp Physiol 2014; 307:R956-69. [PMID: 25121614 DOI: 10.1152/ajpregu.00187.2014] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Physical exercise is a stress that can substantially modulate cellular signaling mechanisms to promote morphological and metabolic adaptations. Skeletal muscle protein and organelle turnover is dependent on two major cellular pathways: Forkhead box class O proteins (FOXO) transcription factors that regulate two main proteolytic systems, the ubiquitin-proteasome, and the autophagy-lysosome systems, including mitochondrial autophagy, and the MTORC1 signaling associated with protein translation and autophagy inhibition. In recent years, it has been well documented that both acute and chronic endurance exercise can affect the autophagy pathway. Importantly, substantial efforts have been made to better understand discrepancies in the literature on its modulation during exercise. A single bout of endurance exercise increases autophagic flux when the duration is long enough, and this response is dependent on nutritional status, since autophagic flux markers and mRNA coding for actors involved in mitophagy are more abundant in the fasted state. In contrast, strength and resistance exercises preferentially raise ubiquitin-proteasome system activity and involve several protein synthesis factors, such as the recently characterized DAGK for mechanistic target of rapamycin activation. In this review, we discuss recent progress on the impact of acute and chronic exercise on cell component turnover systems, with particular focus on autophagy, which until now has been relatively overlooked in skeletal muscle. We especially highlight the most recent studies on the factors that can impact its modulation, including the mode of exercise and the nutritional status, and also discuss the current limitations in the literature to encourage further works on this topic.
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Affiliation(s)
- Anthony M J Sanchez
- Department of Critical Care, McGill University Health Centre and Meakins-Christie Laboratories, Department of Medicine, McGill University, Montreal, Quebec, Canada; University of Perpignan Via Domitia, Laboratoire Performance Santé Altitude, EA 4604, Font-Romeu, France;
| | - Henri Bernardi
- Institut National de la Recherche Agronomique, UMR 866 Dynamique Musculaire et Métabolisme, Montpellier, France; and
| | - Guillaume Py
- Faculty of Sport Sciences, University of Montpellier 1, Montpellier, France
| | - Robin B Candau
- Faculty of Sport Sciences, University of Montpellier 1, Montpellier, France
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Effect of exercise intensity on isoform-specific expressions of NT-PGC-1 α mRNA in mouse skeletal muscle. BIOMED RESEARCH INTERNATIONAL 2014; 2014:402175. [PMID: 25136584 PMCID: PMC4106048 DOI: 10.1155/2014/402175] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/02/2014] [Accepted: 04/28/2014] [Indexed: 11/17/2022]
Abstract
PGC-1α is an inducible transcriptional coactivator that regulates mitochondrial biogenesis and cellular energy metabolism in skeletal muscle. Recent studies have identified two additional PGC-1α transcripts that are derived from an alternative exon 1 (exon 1b) and induced by exercise. Given that the PGC-1α gene also produces NT-PGC-1α transcript by alternative 3′ splicing between exon 6 and exon 7, we have investigated isoform-specific expression of NT-PGC-1α mRNA in mouse skeletal muscle during physical exercise with different intensities. We report here that NT-PGC-1α-a mRNA expression derived from a canonical exon 1 (exon 1a) is increased by high-intensity exercise and AMPK activator AICAR in mouse skeletal muscle but not altered by low- and medium-intensity exercise and β2-adrenergic receptor agonist clenbuterol. In contrast, the alternative exon 1b-driven NT-PGC-1α-b (PGC-1α4) and NT-PGC-1α-c are highly induced by low-, medium-, and high-intensity exercise, AICAR, and clenbuterol. Ectopic expression of NT-PGC-1α-a in C2C12 myotube cells upregulates myosin heavy chain (MHC I, MHC II a) and Glut4, which represent oxidative fibers, and promotes the expression of mitochondrial genes (Cyc1, COX5B, and ATP5B). In line with gene expression data, citrate synthase activity was significantly increased by NT-PGC-1α-a in C2C12 myotube cells. Our results indicate the regulatory role for NT-PGC-1α-a in mitochondrial biogenesis and adaptation of skeletal muscle to endurance exercise.
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Abstract
Skeletal muscle is the largest organ in the body and contributes to innumerable aspects of organismal biology. Muscle dysfunction engenders numerous diseases, including diabetes, cachexia, and sarcopenia. At the same time, skeletal muscle is also the main engine of exercise, one of the most efficacious interventions for prevention and treatment of a wide variety of diseases. The transcriptional coactivator PGC-1α has emerged as a key driver of metabolic programming in skeletal muscle, both in health and in disease. We review here the many aspects of PGC-1α function in skeletal muscle, with a focus on recent developments.
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Affiliation(s)
- Mun Chun Chan
- Cardiovascular Institute and Center for Vascular Biology Research, Beth Israel Deaconess Medical Center and Harvard Medical School
| | - Zolt Arany
- Cardiovascular Institute and Center for Vascular Biology Research, Beth Israel Deaconess Medical Center and Harvard Medical School.
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