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Thomas ACQ, Stead CA, Burniston JG, Phillips SM. Exercise-specific adaptations in human skeletal muscle: Molecular mechanisms of making muscles fit and mighty. Free Radic Biol Med 2024; 223:341-356. [PMID: 39147070 DOI: 10.1016/j.freeradbiomed.2024.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 07/30/2024] [Accepted: 08/09/2024] [Indexed: 08/17/2024]
Abstract
The mechanisms leading to a predominantly hypertrophied phenotype versus a predominantly oxidative phenotype, the hallmarks of resistance training (RT) or aerobic training (AT), respectively, are being unraveled. In humans, exposure of naïve persons to either AT or RT results in their skeletal muscle exhibiting generic 'exercise stress-related' signaling, transcription, and translation responses. However, with increasing engagement in AT or RT, the responses become refined, and the phenotype typically associated with each form of exercise emerges. Here, we review some of the mechanisms underpinning the adaptations of how muscles become, through AT, 'fit' and RT, 'mighty.' Much of our understanding of molecular exercise physiology has arisen from targeted analysis of post-translational modifications and measures of protein synthesis. Phosphorylation of specific residue sites has been a dominant focus, with canonical signaling pathways (AMPK and mTOR) studied extensively in the context of AT and RT, respectively. These alone, along with protein synthesis, have only begun to elucidate key differences in AT and RT signaling. Still, key yet uncharacterized differences exist in signaling and regulation of protein synthesis that drive unique adaptation to AT and RT. Omic studies are required to better understand the divergent relationship between exercise and phenotypic outcomes of training.
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Affiliation(s)
- Aaron C Q Thomas
- Protein Metabolism Research Lab, Department of Kinesiology, McMaster University, Hamilton, ON, Canada; Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Connor A Stead
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Jatin G Burniston
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Stuart M Phillips
- Protein Metabolism Research Lab, Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
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2
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Han X, Ashraf M, Shi H, Nkembo AT, Tipparaju SM, Xuan W. Combined Endurance and Resistance Exercise Mitigates Age-Associated Cardiac Dysfunction. Adv Biol (Weinh) 2024:e2400137. [PMID: 38773896 DOI: 10.1002/adbi.202400137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/07/2024] [Indexed: 05/24/2024]
Abstract
Aging is associated with a decline in cardiac function. Exercise has been shown to effectively reduce the risks of cardiovascular diseases. Here whether a combination of endurance and resistance exercises can improve cardiac function in aged mice during late life is investigated. Through transcriptome analysis, several signaling pathways activated in the hearts of 22-month-old mice after combined exercise, including cardiac muscle contraction, mitophagy, and longevity regulation are identified. Combined exercise training mitigated age-associated pathological cardiac hypertrophy, reduced oxidative stress, cardiac senescence, and enhanced cardiac function. Upstream stimulatory factor 2 (Usf2) is upregulated in the aged mouse hearts with combined exercise compared to sedentary mice. In the human cardiomyocytes senescent model, overexpression of Usf2 led to anti-senescence effects, while knockdown of Usf2 exacerbated cellular senescence. The results suggest that a combination of endurance and resistance exercises, such as swimming and resistance running, can mitigate age-related pathological cardiac remodeling and cardiac dysfunction in late life. These cardioprotective effects are likely due to the activation of Usf2 and its anti-senescence effect. Therefore, Usf2 can potentially be a novel therapeutic target for mitigating age-related cardiac dysfunction.
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Affiliation(s)
- Xiaowei Han
- Department of Pharmaceutical Sciences, USF Health Taneja College of Pharmacy, University of South Florida, Tampa, FL, USA
| | - Muhammad Ashraf
- Department of Pharmaceutical Sciences, USF Health Taneja College of Pharmacy, University of South Florida, Tampa, FL, USA
| | - Hong Shi
- Division of Rheumatology, Department of Internal Medicine, Vascular Biology Center, Augusta University, Augusta, GA, USA
| | - Augustine T Nkembo
- Department of Pharmaceutical Sciences, USF Health Taneja College of Pharmacy, University of South Florida, Tampa, FL, USA
| | - Srinivas M Tipparaju
- Department of Pharmaceutical Sciences, USF Health Taneja College of Pharmacy, University of South Florida, Tampa, FL, USA
| | - Wanling Xuan
- Department of Pharmaceutical Sciences, USF Health Taneja College of Pharmacy, University of South Florida, Tampa, FL, USA
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3
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Kataoka R, Hammert WB, Yamada Y, Song JS, Seffrin A, Kang A, Spitz RW, Wong V, Loenneke JP. The Plateau in Muscle Growth with Resistance Training: An Exploration of Possible Mechanisms. Sports Med 2024; 54:31-48. [PMID: 37787845 DOI: 10.1007/s40279-023-01932-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2023] [Indexed: 10/04/2023]
Abstract
It is hypothesized that there is likely a finite ability for muscular adaptation. While it is difficult to distinguish between a true plateau following a long-term training period and short-term stalling in muscle growth, a plateau in muscle growth has been attributed to reaching a genetic potential, with limited discussion on what might physiologically contribute to this muscle growth plateau. The present paper explores potential physiological factors that may drive the decline in muscle growth after prolonged resistance training. Overall, with chronic training, the anabolic signaling pathways may become more refractory to loading. While measures of anabolic markers may have some predictive capabilities regarding muscle growth adaptation, they do not always demonstrate a clear connection. Catabolic processes may also constrain the ability to achieve further muscle growth, which is influenced by energy balance. Although speculative, muscle cells may also possess cell scaling mechanisms that sense and regulate their own size, along with molecular brakes that hinder growth rate over time. When considering muscle growth over the lifespan, there comes a point when the anabolic response is attenuated by aging, regardless of whether or not individuals approach their muscle growth potential. Our goal is that the current review opens avenues for future experimental studies to further elucidate potential mechanisms to explain why muscle growth may plateau.
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Affiliation(s)
- Ryo Kataoka
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
| | - William B Hammert
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
| | - Yujiro Yamada
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
| | - Jun Seob Song
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
| | - Aldo Seffrin
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
| | - Anna Kang
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
| | - Robert W Spitz
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
| | - Vickie Wong
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
| | - Jeremy P Loenneke
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA.
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Roberts MD, McCarthy JJ, Hornberger TA, Phillips SM, Mackey AL, Nader GA, Boppart MD, Kavazis AN, Reidy PT, Ogasawara R, Libardi CA, Ugrinowitsch C, Booth FW, Esser KA. Mechanisms of mechanical overload-induced skeletal muscle hypertrophy: current understanding and future directions. Physiol Rev 2023; 103:2679-2757. [PMID: 37382939 PMCID: PMC10625844 DOI: 10.1152/physrev.00039.2022] [Citation(s) in RCA: 39] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 06/12/2023] [Accepted: 06/21/2023] [Indexed: 06/30/2023] Open
Abstract
Mechanisms underlying mechanical overload-induced skeletal muscle hypertrophy have been extensively researched since the landmark report by Morpurgo (1897) of "work-induced hypertrophy" in dogs that were treadmill trained. Much of the preclinical rodent and human resistance training research to date supports that involved mechanisms include enhanced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, an expansion in translational capacity through ribosome biogenesis, increased satellite cell abundance and myonuclear accretion, and postexercise elevations in muscle protein synthesis rates. However, several lines of past and emerging evidence suggest that additional mechanisms that feed into or are independent of these processes are also involved. This review first provides a historical account of how mechanistic research into skeletal muscle hypertrophy has progressed. A comprehensive list of mechanisms associated with skeletal muscle hypertrophy is then outlined, and areas of disagreement involving these mechanisms are presented. Finally, future research directions involving many of the discussed mechanisms are proposed.
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Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - John J McCarthy
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States
| | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Stuart M Phillips
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Abigail L Mackey
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital-Bispebjerg and Frederiksberg, and Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Gustavo A Nader
- Department of Kinesiology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - Marni D Boppart
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
| | - Andreas N Kavazis
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Paul T Reidy
- Department of Kinesiology, Nutrition and Health, Miami University, Oxford, Ohio, United States
| | - Riki Ogasawara
- Healthy Food Science Research Group, Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Cleiton A Libardi
- MUSCULAB-Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of São Carlos, São Carlos, Brazil
| | - Carlos Ugrinowitsch
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Frank W Booth
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, United States
| | - Karyn A Esser
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, Florida, United States
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Mannozzi J, Al-Hassan MH, Kaur J, Lessanework B, Alvarez A, Massoud L, Aoun K, Spranger M, O'Leary DS. Blood flow restriction training activates the muscle metaboreflex during low-intensity sustained exercise. J Appl Physiol (1985) 2023; 135:260-270. [PMID: 37348015 PMCID: PMC10393340 DOI: 10.1152/japplphysiol.00274.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 06/09/2023] [Indexed: 06/24/2023] Open
Abstract
Blood flow restriction training (BFRT) employs partial vascular occlusion of exercising muscle and has been shown to increase muscle performance while using reduced workload and training time. Numerous studies have demonstrated that BFRT increases muscle hypertrophy, mitochondrial function, and beneficial vascular adaptations. However, changes in cardiovascular hemodynamics during the exercise protocol remain unknown, as most studies measured blood pressure before the onset and after the cessation of exercise. With reduced perfusion to the exercising muscle during BFRT, the resultant accumulation of metabolites within the ischemic muscle could potentially trigger a large reflex increase in blood pressure, termed the muscle metaboreflex. At low workloads, this pressor response occurs primarily via increases in cardiac output. However, when increases in cardiac output are limited (e.g., heart failure or during severe exercise), the reflex shifts to peripheral vasoconstriction as the primary mechanism to increase blood pressure, potentially increasing the risk of a cardiovascular event. Using our chronically instrumented conscious canine model, we utilized a 60% reduction in femoral blood pressure applied to the hindlimbs during steady-state treadmill exercise (3.2 km/h) to reproduce the ischemic environment observed during BFRT. We observed significant increases in heart rate (+19 ± 3 beats/min), stroke volume (+2.52 ± 1.2 mL), cardiac output (+1.21 ± 0.2 L/min), mean arterial pressure (+18.2 ± 2.4 mmHg), stroke work (+1.93 ± 0.2 L/mmHg), and nonischemic vascular conductance (+3.62 ± 1.7 mL/mmHg), indicating activation of the muscle metaboreflex.NEW & NOTEWORTHY Blood flow restriction training (BFRT) increases muscle mass, strength, and endurance. There has been minimal consideration of the reflex cardiovascular responses that could be elicited during BFRT sessions. We showed that during low-intensity exercise BFRT may trigger large reflex increases in blood pressure and sympathetic activity due to muscle metaboreflex activation. Thus, we urge caution when employing BFRT, especially in patients in whom exaggerated cardiovascular responses may occur that could cause sudden, adverse cardiovascular events.
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Affiliation(s)
- Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Mohamed-Hussein Al-Hassan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Jasdeep Kaur
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States
| | - Beruk Lessanework
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Alberto Alvarez
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Louis Massoud
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Kamel Aoun
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Marty Spranger
- Department of Physiology, Michigan State University, East Lansing, Michigan, United States
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
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Uemichi K, Shirai T, Takemasa T. Combined effects of functional overload and denervation on skeletal muscle mass and its regulatory proteins in mice. Physiol Rep 2023; 11:e15689. [PMID: 37161590 PMCID: PMC10169777 DOI: 10.14814/phy2.15689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 03/29/2023] [Accepted: 03/31/2023] [Indexed: 05/11/2023] Open
Abstract
Skeletal muscle is a highly pliable tissue and various adaptations such as muscle hypertrophy or atrophy are induced by overloading or disuse, respectively. However, the combined effect of overloading and disuse on the quantitative adaptation of skeletal muscle is unknown. Thus, the aim of this study was to investigate the effects of the combined stimuli of overloading and disuse on mouse skeletal muscle mass and the expression of regulatory factors for muscle protein anabolism or catabolism. Male mice from the Institute Cancer Research were subjected to denervation concomitant with unilateral functional overload or functional overload concomitant with unilateral denervation. Disuse and functional overload were induced by sciatic nerve transection (denervation) and synergist ablation, respectively, and the plantaris muscle was harvested 14 days after the operation. Our results showed that denervation attenuated functional overload-induced muscle hypertrophy and functional overload partially ameliorated the denervation-induced muscle atrophy. P70S6K phosphorylation, an indicator of mechanistic target of rapamycin complex 1 (mTORC1) activation, was not increased by unilateral functional overload in denervated muscles or by unilateral denervation in functional overloaded muscles. Denervation did not affect the increase of LC3-II, a marker of autophagy activation, and ubiquitinated protein expression upon unilateral functional overload. Also, functional overload did not affect ubiquitinated protein expression during unilateral denervation. Thus, our findings suggest that functional overload-induced muscle hypertrophy or denervation-induced muscle atrophy was attenuated by the combined stimuli of overload and denervation.
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Affiliation(s)
- Kazuki Uemichi
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
| | - Takanaga Shirai
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
| | - Tohru Takemasa
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
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Roy A, Narkar VA, Kumar A. Emerging role of TAK1 in the regulation of skeletal muscle mass. Bioessays 2023; 45:e2300003. [PMID: 36789559 PMCID: PMC10023406 DOI: 10.1002/bies.202300003] [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: 01/06/2023] [Revised: 01/02/2023] [Accepted: 02/02/2023] [Indexed: 02/16/2023]
Abstract
Maintenance of skeletal muscle mass and strength throughout life is crucial for heathy living and longevity. Several signaling pathways have been implicated in the regulation of skeletal muscle mass in adults. TGF-β-activated kinase 1 (TAK1) is a key protein, which coordinates the activation of multiple signaling pathways. Recently, it was discovered that TAK1 is essential for the maintenance of skeletal muscle mass and myofiber hypertrophy following mechanical overload. Forced activation of TAK1 in skeletal muscle causes hypertrophy and attenuates denervation-induced muscle atrophy. TAK1-mediated signaling in skeletal muscle promotes protein synthesis, redox homeostasis, mitochondrial health, and integrity of neuromuscular junctions. In this article, we have reviewed the role and potential mechanisms through which TAK1 regulates skeletal muscle mass and growth. We have also proposed future areas of research that could be instrumental in exploring TAK1 as therapeutic target for improving muscle mass in various catabolic conditions and diseases.
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Affiliation(s)
- Anirban Roy
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204, USA
| | - Vihang A. Narkar
- Brown Foundation Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center, Houston, Texas, USA
| | - Ashok Kumar
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Houston, TX 77204, USA
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Uemichi K, Shirai T, Matsuno R, Iwata T, Tanimura R, Takemasa T. The role of the mechanistic target of rapamycin complex 1 in the regulation of mitochondrial adaptation during skeletal muscle atrophy under denervation or calorie restriction in mice. Appl Physiol Nutr Metab 2023; 48:241-255. [PMID: 36786420 DOI: 10.1139/apnm-2022-0336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a protein complex that regulates skeletal muscle protein synthesis and hypertrophy. mTORC1-mediated signaling activities are activated during denervation-induced skeletal muscle atrophy and suppressed during calorie restriction-induced atrophy. Mitochondria control the qualitative plasticity of skeletal muscles primarily through biogenesis, fusion, and fission. We recently showed that mTORC1 activation contributes toward mitochondrial homeostasis. In this study, we examined the role of mTORC1 in mitochondrial adaptation during denervation- or calorie restriction-induced skeletal muscle atrophy. Seven-week-old Institute of Cancer Research mice were subjected to 14 days of denervation or calorie restriction combined with the administration of the mTORC1 inhibitor-"rapamycin". Our results showed that although mTORC1 inhibition did not alter mitochondrial biogenesis, content and enzyme activity, it suppressed the activation of dynamin-related protein 1 (DRP1), a mitochondrial fission-related protein in denervated muscle, and reduced DRP1 expression in calorie-restricted muscle. Furthermore, calorie restriction-induced mitochondrial fragmentation was partially suppressed by mTORC1 inhibition. Taken together, our results indicate that mTORC1 activation upon denervation and inhibition upon calorie restriction contributes to qualitative changes in muscle plasticity by at least partially regulating the mitochondrial fission response.
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Affiliation(s)
- Kazuki Uemichi
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
| | - Takanaga Shirai
- Research Fellow of the Japan Society for the Promotion of Science, Tokyo, Japan.,Faculty of Health and Sports Sciences, University of Tsukuba, Tsukuba, Japan
| | - Ryunosuke Matsuno
- School of Physical Education, Health and Sports Sciences, University of Tsukuba, Tsukuba, Japan.,Terumo Corporation, Tokyo, Japan
| | - Tomohiro Iwata
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
| | - Riku Tanimura
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tohru Takemasa
- Faculty of Health and Sports Sciences, University of Tsukuba, Tsukuba, Japan
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Alcohol, Resistance Exercise, and mTOR Pathway Signaling: An Evidence-Based Narrative Review. Biomolecules 2022; 13:biom13010002. [PMID: 36671386 PMCID: PMC9855961 DOI: 10.3390/biom13010002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/14/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022] Open
Abstract
Skeletal muscle mass is determined by the balance between muscle protein synthesis (MPS) and degradation. Several intracellular signaling pathways control this balance, including mammalian/mechanistic target of rapamycin (mTOR) complex 1 (C1). Activation of this pathway in skeletal muscle is controlled, in part, by nutrition (e.g., amino acids and alcohol) and exercise (e.g., resistance exercise (RE)). Acute and chronic alcohol use can result in myopathy, and evidence points to altered mTORC1 signaling as a contributing factor. Moreover, individuals who regularly perform RE or vigorous aerobic exercise are more likely to use alcohol frequently and in larger quantities. Therefore, alcohol may antagonize beneficial exercise-induced increases in mTORC1 pathway signaling. The purpose of this review is to synthesize up-to-date evidence regarding mTORC1 pathway signaling and the independent and combined effects of acute alcohol and RE on activation of the mTORC1 pathway. Overall, acute alcohol impairs and RE activates mTORC1 pathway signaling; however, effects vary by model, sex, feeding, training status, quantity, etc., such that anabolic stimuli may partially rescue the alcohol-mediated pathway inhibition. Likewise, the impact of alcohol on RE-induced mTORC1 pathway signaling appears dependent on several factors including nutrition and sex, although many questions remain unanswered. Accordingly, we identify gaps in the literature that remain to be elucidated to fully understand the independent and combined impacts of alcohol and RE on mTORC1 pathway signaling.
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Vainshtein A, Slavin MB, Cheng AJ, Memme JM, Oliveira AN, Perry CGR, Abdul-Sater AA, Belcastro AN, Riddell MC, Triolo M, Haas TL, Roudier E, Hood DA. Scientific meeting report: International Biochemistry of Exercise 2022. J Appl Physiol (1985) 2022; 133:1381-1393. [PMID: 36356257 DOI: 10.1152/japplphysiol.00475.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Exercise is one of the only nonpharmacological remedies known to counteract genetic and chronic diseases by enhancing health and improving life span. Although the many benefits of regular physical activity have been recognized for some time, the intricate and complex signaling systems triggered at the onset of exercise have only recently begun to be uncovered. Exercising muscles initiate a coordinated, multisystemic, metabolic rewiring, which is communicated to distant organs by various molecular mediators. The field of exercise research has been expanding beyond the musculoskeletal system, with interest from industry to provide realistic models and exercise mimetics that evoke a whole body rejuvenation response. The 18th International Biochemistry of Exercise conference took place in Toronto, Canada, from May 25 to May 28, 2022, with more than 400 attendees. Here, we provide an overview of the most cutting-edge exercise-related research presented by 66 speakers, focusing on new developments in topics ranging from molecular and cellular mechanisms of exercise adaptations to exercise therapy and management of disease and aging. We also describe how the manipulation of these signaling pathways can uncover therapeutic avenues for improving human health and quality of life.
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Affiliation(s)
| | - Mikhaela B Slavin
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Arthur J Cheng
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Jonathan M Memme
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Ashley N Oliveira
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Christopher G R Perry
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Ali A Abdul-Sater
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Angelo N Belcastro
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Michael C Riddell
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Matthew Triolo
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Tara L Haas
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - Emilie Roudier
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
| | - David A Hood
- Faculty of Health, School of Kinesiology and Health Science, Muscle Health Research Centre (MHRC), York University, Toronto, Ontario, Canada
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11
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D'Hulst G, Masschelein E, De Bock K. Resistance exercise enhances long-term mTORC1 sensitivity to leucine. Mol Metab 2022; 66:101615. [PMID: 36252815 PMCID: PMC9626937 DOI: 10.1016/j.molmet.2022.101615] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 10/07/2022] [Accepted: 10/12/2022] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE Exercise enhances the sensitivity of mammalian target of rapamycin complex 1 (mTORC1) to amino acids, in particular leucine. How long this enhanced sensitivity lasts, and which mechanisms control enhanced leucine-mediated mTORC1 activation following exercise is currently unknown. METHODS C57BL/6J mice were exercised for one night in a resistance-braked running wheel after a 12-day acclimatization period. Mice were gavaged with a submaximal dose of l-leucine or saline acutely or 48 h after exercise cessation, following 3 h food withdrawal. Muscles were excised 30 min after leucine administration. To study the contribution of mTORC1, we repeated those experiments but blocked mTORC1 activation using rapamycin immediately before the overnight running bout and one hour before the first dose of leucine. mTORC1 signaling, muscle protein synthesis and amino acid sensing machinery were assessed using immunoblot and qPCR. Leucine uptake was measured using L-[14C(U)]-leucine tracer labeling. RESULTS When compared to sedentary conditions, leucine supplementation more potently activated mTORC1 and protein synthesis in acutely exercised muscle. This effect was observed in m. soleus but not in m. tibialis anterior nor m. plantaris. The synergistic effect in m. soleus was long-lasting as key downstream markers of mTORC1 as well as protein synthesis remained higher when leucine was administered 48 h after exercise. We found that exercise enhanced the expression of amino acid transporters and promoted uptake of leucine into the muscle, leading to higher free intramuscular leucine levels. This coincided with increased expression of activating transcription factor 4 (ATF4), a main transcriptional regulator of amino acid uptake and metabolism, and downstream activation of amino acid genes as well as leucyl-tRNA synthetase (LARS), a putative leucine sensor. Finally, blocking mTORC1 using rapamycin did not reduce expression and activation of ATF4, suggesting that the latter does not act downstream of mTORC1. Rather, we found a robust increase in eukaryotic initiation factor 2α (eIF2α) phosphorylation, suggesting that the integrated stress response pathway, rather than exercise-induced mTORC1 activation, drives long-term ATF4 expression in skeletal muscle after exercise. CONCLUSIONS The enhanced sensitivity of mTORC1 to leucine is maintained at least 48 h after exercise. This shows that the anabolic window of opportunity for protein ingestion is not restricted to the first hours immediately following exercise. Increased mTORC1 sensitivity to leucine coincided with enhanced leucine influx into muscle and higher expression of genes involved in leucine sensing and amino acid metabolism. Also, exercise induced an increase in ATF4 protein expression. Altogether, these data suggest that muscular contractions switch on a coordinated program to enhance amino acid uptake as well as intramuscular sensing of key amino acids involved in mTORC1 activation and the stimulation of muscle protein synthesis.
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Affiliation(s)
- Gommaar D'Hulst
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zürich, Switzerland
| | - Evi Masschelein
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zürich, Switzerland
| | - Katrien De Bock
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zürich, Switzerland.
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12
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Abstract
Skeletal muscle mass is a very plastic characteristic of skeletal muscle and is regulated by signaling pathways that control the balance between anabolic and catabolic processes. The serine/threonine kinase mechanistic/mammalian target of rapamycin (mTOR) has been shown to be critically important in the regulation of skeletal muscle mass through its regulation of protein synthesis and degradation pathways. In this commentary, recent advances in the understanding of the role of mTORC1 in the regulation of muscle mass under conditions that induce hypertrophy and atrophy will be highlighted.
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Affiliation(s)
- Sue C Bodine
- Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, IA 52242, USA
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13
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LIM CHANGHYUN, NUNES EVERSONA, CURRIER BRADS, MCLEOD JONATHANC, THOMAS AARONCQ, PHILLIPS STUARTM. An Evidence-Based Narrative Review of Mechanisms of Resistance Exercise-Induced Human Skeletal Muscle Hypertrophy. Med Sci Sports Exerc 2022; 54:1546-1559. [PMID: 35389932 PMCID: PMC9390238 DOI: 10.1249/mss.0000000000002929] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Skeletal muscle plays a critical role in physical function and metabolic health. Muscle is a highly adaptable tissue that responds to resistance exercise (RE; loading) by hypertrophying, or during muscle disuse, RE mitigates muscle loss. Resistance exercise training (RET)-induced skeletal muscle hypertrophy is a product of external (e.g., RE programming, diet, some supplements) and internal variables (e.g., mechanotransduction, ribosomes, gene expression, satellite cells activity). RE is undeniably the most potent nonpharmacological external variable to stimulate the activation/suppression of internal variables linked to muscular hypertrophy or countering disuse-induced muscle loss. Here, we posit that despite considerable research on the impact of external variables on RET and hypertrophy, internal variables (i.e., inherent skeletal muscle biology) are dominant in regulating the extent of hypertrophy in response to external stimuli. Thus, identifying the key internal skeletal muscle-derived variables that mediate the translation of external RE variables will be pivotal to determining the most effective strategies for skeletal muscle hypertrophy in healthy persons. Such work will aid in enhancing function in clinical populations, slowing functional decline, and promoting physical mobility. We provide up-to-date, evidence-based perspectives of the mechanisms regulating RET-induced skeletal muscle hypertrophy.
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Affiliation(s)
- CHANGHYUN LIM
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
| | - EVERSON A. NUNES
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
- Department of Physiological Science, Federal University of Santa Catarina, Florianópolis, Santa-Catarina, BRAZIL
| | - BRAD S. CURRIER
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
| | - JONATHAN C. MCLEOD
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
| | - AARON C. Q. THOMAS
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
| | - STUART M. PHILLIPS
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
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14
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Gonzalez A, Abrigo J, Achiardi O, Simon F, Cabello-Verrugio C. Intensive care unit-acquired weakness: From molecular mechanisms to its impact in COVID-2019. Eur J Transl Myol 2022; 32. [PMID: 36036350 PMCID: PMC9580540 DOI: 10.4081/ejtm.2022.10511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 08/08/2022] [Indexed: 01/08/2023] Open
Abstract
Intensive Care Unit-Acquired Weakness (ICU-AW) is a generalized and symmetric neuromuscular dysfunction associated with critical illness and its treatments. Its incidence is approximately 80% in intensive care unit patients, and it manifests as critical illness polyneuropathy, critical illness myopathy, and muscle atrophy. Intensive care unit patients can lose an elevated percentage of their muscle mass in the first days after admission, producing short- and long-term sequelae that affect patients’ quality of life, physical health, and mental health. In 2019, the world was faced with coronavirus disease 2019 (COVID-19), caused by the acute respiratory syndrome coronavirus 2. COVID-19 produces severe respiratory disorders, such as acute respiratory distress syndrome, which increases the risk of developing ICU-AW. COVID-19 patients treated in intensive care units have shown early diffuse and symmetrical muscle weakness, polyneuropathy, and myalgia, coinciding with the clinical presentation of ICU-AW. Besides, these patients require prolonged intensive care unit stays, invasive mechanical ventilation, and intensive care unit pharmacological therapy, which are risk factors for ICU-AW. Thus, the purposes of this review are to discuss the features of ICU-AW and its effects on skeletal muscle. Further, we will describe the mechanisms involved in the probable development of ICU-AW in severe COVID-19 patients.
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15
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Mori T, Ato S, Knudsen JR, Henriquez-Olguin C, Li Z, Wakabayashi K, Suginohara T, Higashida K, Tamura Y, Nakazato K, Jensen TE, Ogasawara R. c-Myc overexpression increases ribosome biogenesis and protein synthesis independent of mTORC1 activation in mouse skeletal muscle. Am J Physiol Endocrinol Metab 2021; 321:E551-E559. [PMID: 34423683 DOI: 10.1152/ajpendo.00164.2021] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
High-intensity muscle contractions (HiMCs) are known to increase c-Myc expression that is known to stimulate ribosome biogenesis and protein synthesis in most cells. However, although c-Myc mRNA transcription and c-Myc mRNA translation have been shown to be upregulated following resistance exercise concomitantly with increased ribosome biogenesis, this connection has not been tested directly. We investigated the effect of adeno-associated virus (AAV)-mediated c-Myc overexpression, with or without fasting or percutaneous electrical stimulation-induced HiMC, on ribosome biogenesis and protein synthesis in adult mouse skeletal muscles. AAV-mediated overexpression of c-Myc in mouse skeletal muscles for 2 wk increased the DNA polymerase subunit POL1 mRNA, 45S-pre-rRNA, total RNA, and muscle protein synthesis without altering mechanistic target of rapamycin complex 1 (mTORC1) signaling under both ad libitum and fasted conditions. RNA-sequencing (RNA-seq) analyses revealed that c-Myc overexpression mainly regulated ribosome biogenesis-related biological processes. The protein synthesis response to c-Myc overexpression mirrored the response with HiMC. No additional effect of combining c-Myc overexpression and HiMC was observed. Our results suggest that c-Myc overexpression is sufficient to stimulate skeletal muscle ribosome biogenesis and protein synthesis without activation of mTORC1. Therefore, the HiMC-induced increase in c-Myc may contribute to ribosome biogenesis and increased protein synthesis following HiMC.NEW & NOTEWORTHY Resistance exercise is known to increase c-Myc expression, which is known to stimulate ribosome biogenesis and protein synthesis in a variety of cells. However, whether the increase in c-Myc stimulates ribosome biogenesis and protein synthesis in skeletal muscles remains unknown. We found that c-Myc overexpression is sufficient to stimulate skeletal muscle ribosome biogenesis and protein synthesis without activation of mTORC1.
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Affiliation(s)
- Takahiro Mori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Satoru Ato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Jonas R Knudsen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
- Microsystems Laboratory 2, Institute of Microengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Carlos Henriquez-Olguin
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Zhencheng Li
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Koki Wakabayashi
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Takeshi Suginohara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | | | - Yuki Tamura
- Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan
| | - Koichi Nakazato
- Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan
| | - Thomas E Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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16
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Nishimura Y, Musa I, Holm L, Lai YC. Recent advances in measuring and understanding the regulation of exercise-mediated protein degradation in skeletal muscle. Am J Physiol Cell Physiol 2021; 321:C276-C287. [PMID: 34038244 DOI: 10.1152/ajpcell.00115.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Skeletal muscle protein turnover plays a crucial role in controlling muscle mass and protein quality control, including sarcomeric (structural and contractile) proteins. Protein turnover is a dynamic and continual process of protein synthesis and degradation. The ubiquitin proteasome system (UPS) is a key degradative system for protein degradation and protein quality control in skeletal muscle. UPS-mediated protein quality control is known to be impaired in aging and diseases. Exercise is a well-recognized, nonpharmacological approach to promote muscle protein turnover rates. Over the past decades, we have acquired substantial knowledge of molecular mechanisms of muscle protein synthesis after exercise. However, there have been considerable gaps in the mechanisms of how muscle protein degradation is regulated at the molecular level. The main challenge to understand muscle protein degradation is due in part to the lack of solid stable isotope tracer methodology to measure muscle protein degradation rate. Understanding the mechanisms of UPS with the concomitant measurement of protein degradation rate in skeletal muscle will help identify novel therapeutic strategies to ameliorate impaired protein turnover and protein quality control in aging and diseases. Thus, the goal of this present review was to highlight how recent advances in the field may help improve our understanding of exercise-mediated protein degradation. We discuss 1) the emerging roles of protein phosphorylation and ubiquitylation modifications in regulating proteasome-mediated protein degradation after exercise and 2) methodological advances to measure in vivo myofibrillar protein degradation rate using stable isotope tracer methods.
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Affiliation(s)
- Yusuke Nishimura
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Ibrahim Musa
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Lars Holm
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, University of Birmingham, Birmingham, United Kingdom
| | - Yu-Chiang Lai
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, University of Birmingham, Birmingham, United Kingdom
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
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17
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Padilha CS, Cella PS, Chimin P, Voltarelli FA, Marinello PC, Testa MTDEJ, Guirro PB, Duarte JAR, Cecchini R, Guarnier FA, Deminice R. Resistance Training's Ability to Prevent Cancer-induced Muscle Atrophy Extends Anabolic Stimulus. Med Sci Sports Exerc 2021; 53:1572-1582. [PMID: 33731662 DOI: 10.1249/mss.0000000000002624] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE This study aimed to determine the role of mammalian target of rapamycin (mTORC1) activation and catabolic markers in resistance training's (RT) antiatrophy effect during cachexia-induced muscle loss. METHODS Myofiber atrophy was induced by injecting Walker 256 tumor cells into rats exposed or not exposed to the RT protocol of ladder climbing. The role of RT-induced anabolic stimulation was investigated in tumor-bearing rats with the mTORC1 inhibitor rapamycin, and cross-sectional areas of skeletal muscle were evaluated to identify atrophy or hypertrophy. Components of the mTORC1 and ubiquitin-proteasome pathways were assessed by real-time polymerase chain reaction or immunoblotting. RESULTS Although RT prevented myofiber atrophy and impaired the strength of tumor-bearing rats, in healthy rats, it promoted activated mTORC1, as demonstrated by p70S6K's increased phosphorylation and myofiber's enlarged cross-sectional area. However, RT promoted no changes in the ratio of p70S6K to phospho-p70S6K protein expression while prevented myofiber atrophy in tumor-bearing rats. Beyond that, treatment with rapamycin did not preclude RT's preventive effect on myofiber atrophy in tumor-bearing rats. Thus, RT's ability to prevent cancer-induced myofiber atrophy seems to be independent of mTORC1's and p70S6K's activation. Indeed, RT's preventive effect on cancer-induced myofiber atrophy was associated with its capacity to attenuate elevated tumor necrosis factor α and interleukin 6 as well as to prevent oxidative damage in muscles and an elevated abundance of atrogin-1. CONCLUSIONS By inducing attenuated myofiber atrophy independent of mTORC1's signaling activation, RT prevents muscle atrophy during cancer by reducing inflammation, oxidative damage, and atrogin-1 expression.
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Affiliation(s)
| | - Paola S Cella
- Department of Physical Education, State University of Londrina, Londrina, PR, BRAZIL
| | - Patrícia Chimin
- Department of Physical Education, State University of Londrina, Londrina, PR, BRAZIL
| | - Fabrício A Voltarelli
- Federal University of Mato Grosso, Graduate Program of Health Sciences, Faculty of Medicine, Cuiabá, BRAZIL
| | | | | | - Philippe B Guirro
- Department of Physical Education, State University of Londrina, Londrina, PR, BRAZIL
| | - José A R Duarte
- University of Porto, CIAFEL, Faculty of Sport, Porto, PORTUGAL
| | - Rubens Cecchini
- State University of Londrina, Department of General Pathology, Londrina, PR, BRAZIL
| | - Flávia A Guarnier
- State University of Londrina, Department of General Pathology, Londrina, PR, BRAZIL
| | - Rafael Deminice
- Department of Physical Education, State University of Londrina, Londrina, PR, BRAZIL
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18
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Li J, Knudsen JR, Henriquez-Olguin C, Li Z, Birk JB, Persson KW, Hellsten Y, Offergeld A, Jarassier W, Le Grand F, Schjerling P, Wojtaszewski JFP, Jensen TE. AXIN1 knockout does not alter AMPK/mTORC1 regulation and glucose metabolism in mouse skeletal muscle. J Physiol 2021; 599:3081-3100. [PMID: 33913171 DOI: 10.1113/jp281187] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/20/2021] [Indexed: 01/15/2023] Open
Abstract
KEY POINTS Tamoxifen-inducible skeletal muscle-specific AXIN1 knockout (AXIN1 imKO) in mouse does not affect whole-body energy substrate metabolism. AXIN1 imKO does not affect AICAR or insulin-stimulated glucose uptake in adult skeletal muscle. AXIN1 imKO does not affect adult skeletal muscle AMPK or mTORC1 signalling during AICAR/insulin/amino acid incubation, contraction and exercise. During exercise, α2/β2/γ3AMPK and AMP/ATP ratio show greater increases in AXIN1 imKO than wild-type in gastrocnemius muscle. ABSTRACT AXIN1 is a scaffold protein known to interact with >20 proteins in signal transduction pathways regulating cellular development and function. Recently, AXIN1 was proposed to assemble a protein complex essential to catabolic-anabolic transition by coordinating AMPK activation and inactivation of mTORC1 and to regulate glucose uptake-stimulation by both AMPK and insulin. To investigate whether AXIN1 is permissive for adult skeletal muscle function, a phenotypic in vivo and ex vivo characterization of tamoxifen-inducible skeletal muscle-specific AXIN1 knockout (AXIN1 imKO) mice was conducted. AXIN1 imKO did not influence AMPK/mTORC1 signalling or glucose uptake stimulation at rest or in response to different exercise/contraction protocols, pharmacological AMPK activation, insulin or amino acids stimulation. The only genotypic difference observed was in exercising gastrocnemius muscle, where AXIN1 imKO displayed elevated α2/β2/γ3 AMPK activity and AMP/ATP ratio compared to wild-type mice. Our work shows that AXIN1 imKO generally does not affect skeletal muscle AMPK/mTORC1 signalling and glucose metabolism, probably due to functional redundancy of its homologue AXIN2.
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Affiliation(s)
- Jingwen Li
- Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Jonas R Knudsen
- Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.,Microsystems Laboratory 2, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Carlos Henriquez-Olguin
- Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Zhencheng Li
- Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Jesper B Birk
- Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Kaspar W Persson
- Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Ylva Hellsten
- Section for Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Anika Offergeld
- School of Bioscience, Cardiff University, Cardiff, CF10 3AX, UK
| | - William Jarassier
- Institut NeuroMyoGène, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France
| | - Fabien Le Grand
- Institut NeuroMyoGène, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France
| | - Peter Schjerling
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark
| | - Jørgen F P Wojtaszewski
- Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E Jensen
- Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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19
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Graham ZA, Lavin KM, O'Bryan SM, Thalacker-Mercer AE, Buford TW, Ford KM, Broderick TJ, Bamman MM. Mechanisms of exercise as a preventative measure to muscle wasting. Am J Physiol Cell Physiol 2021; 321:C40-C57. [PMID: 33950699 DOI: 10.1152/ajpcell.00056.2021] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Skeletal muscle is the most abundant tissue in healthy individuals and it has important roles in health beyond voluntary movement. The overall mass and energy requirements of skeletal muscle require it to be metabolically active and flexible to multiple energy substrates. The tissue has evolved to be largely load dependent and it readily adapts in a number of positive ways to repetitive overload, such as various forms of exercise training. However, unloading from extended bed rest and/or metabolic derangements in response to trauma, acute illness, or severe pathology, commonly results in rapid muscle wasting. Decline in muscle mass contributes to multimorbidity, reduces function, and exerts a substantial, negative impact on the quality of life. The principal mechanisms controlling muscle mass have been well described and these cellular processes are intricately regulated by exercise. Accordingly, exercise has shown great promise and efficacy in preventing or slowing muscle wasting through changes in molecular physiology, organelle function, cell signaling pathways, and epigenetic regulation. In this review, we focus on the role of exercise in altering the molecular landscape of skeletal muscle in a manner that improves or maintains its health and function in the presence of unloading or disease.epigenetics; exercise; muscle wasting; resistance training; skeletal muscle.
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Affiliation(s)
- Zachary A Graham
- Birmingham VA Medical Center, Birmingham, Alabama.,Florida Institute for Human and Machine Cognition, Pensacola, Florida.,Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama.,UAB Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama
| | - Kaleen M Lavin
- Florida Institute for Human and Machine Cognition, Pensacola, Florida.,Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama.,UAB Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama
| | - Samia M O'Bryan
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama.,UAB Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama
| | - Anna E Thalacker-Mercer
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama.,UAB Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama
| | - Thomas W Buford
- UAB Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama.,Division of Gerontology, Geriatrics and Palliative Care, Department of Medicine, The University of Alabama at Birmingham, Birmingham, Alabama.,Nathan Shock Center, The University of Alabama at Birmingham, Birmingham, Alabama
| | - Kenneth M Ford
- Florida Institute for Human and Machine Cognition, Pensacola, Florida
| | | | - Marcas M Bamman
- Florida Institute for Human and Machine Cognition, Pensacola, Florida.,Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama.,UAB Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama.,Division of Gerontology, Geriatrics and Palliative Care, Department of Medicine, The University of Alabama at Birmingham, Birmingham, Alabama
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20
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Haxhi J, Thompson PD. Rationale for the use of metformin and exercise to counteract statin-associated side effects. Int J Clin Pract 2021; 75:e13900. [PMID: 33277775 DOI: 10.1111/ijcp.13900] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 12/01/2020] [Indexed: 12/16/2022] Open
Abstract
INTRODUCTION Statins are the most widely prescribed drugs for lowering low-density lipoprotein cholesterol (LDL-C) and reducing cardiovascular morbidity and mortality. They are usually well-tolerated, but have two main safety concerns: statin-associated muscle symptoms (SAMS) and new-onset type 2 diabetes (NOD). METHODS A PubMed search was carried out using the following key words were used: statins, statin-associated muscle symptoms, statin myalgia, statin-associated diabetes, metformin and statins, exercise and statins. RESULTS Mitochondrial damage and muscle atrophy are likely the central mechanisms producing SAMS, whereas decreased glucose transport, fatty acid oxidation and insulin secretion are likely involved in the development of NOD. Metformin and exercise training share many pathways that could potentially contrast SAMS and NOD. Clinical evidence also supports the combination of statins with metformin and exercise. CONCLUSION This combination appears attractive both from a clinical and an economical viewpoint, since all three therapies are highly cost-effective and their combination could result in diabetes and cardiovascular disease prevention.
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Affiliation(s)
- Jonida Haxhi
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
- Division of Cardiology, Hartford Hospital, Hartford, CT, USA
| | - Paul D Thompson
- Division of Cardiology, Hartford Hospital, Hartford, CT, USA
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21
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Hyatt HW, Powers SK. Mitochondrial Dysfunction Is a Common Denominator Linking Skeletal Muscle Wasting Due to Disease, Aging, and Prolonged Inactivity. Antioxidants (Basel) 2021; 10:antiox10040588. [PMID: 33920468 PMCID: PMC8070615 DOI: 10.3390/antiox10040588] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 04/02/2021] [Accepted: 04/07/2021] [Indexed: 12/29/2022] Open
Abstract
Skeletal muscle is the most abundant tissue in the body and is required for numerous vital functions, including breathing and locomotion. Notably, deterioration of skeletal muscle mass is also highly correlated to mortality in patients suffering from chronic diseases (e.g., cancer). Numerous conditions can promote skeletal muscle wasting, including several chronic diseases, cancer chemotherapy, aging, and prolonged inactivity. Although the mechanisms responsible for this loss of muscle mass is multifactorial, mitochondrial dysfunction is predicted to be a major contributor to muscle wasting in various conditions. This systematic review will highlight the biochemical pathways that have been shown to link mitochondrial dysfunction to skeletal muscle wasting. Importantly, we will discuss the experimental evidence that connects mitochondrial dysfunction to muscle wasting in specific diseases (i.e., cancer and sepsis), aging, cancer chemotherapy, and prolonged muscle inactivity (e.g., limb immobilization). Finally, in hopes of stimulating future research, we conclude with a discussion of important future directions for research in the field of muscle wasting.
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22
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Steinert ND, Potts GK, Wilson GM, Klamen AM, Lin KH, Hermanson JB, McNally RM, Coon JJ, Hornberger TA. Mapping of the contraction-induced phosphoproteome identifies TRIM28 as a significant regulator of skeletal muscle size and function. Cell Rep 2021; 34:108796. [PMID: 33657380 PMCID: PMC7967290 DOI: 10.1016/j.celrep.2021.108796] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 01/11/2021] [Accepted: 02/05/2021] [Indexed: 12/25/2022] Open
Abstract
Mechanical signals, such as those evoked by maximal-intensity contractions (MICs), can induce an increase in muscle mass. Rapamycin-sensitive signaling events are widely implicated in the regulation of this process; however, recent studies indicate that rapamycin-insensitive signaling events are also involved. Thus, to identify these events, we generate a map of the MIC-regulated and rapamycin-sensitive phosphoproteome. In total, we quantify more than 10,000 unique phosphorylation sites and find that more than 2,000 of these sites are significantly affected by MICs, but remarkably, only 38 of the MIC-regulated events are mediated through a rapamycin-sensitive mechanism. Further interrogation of the rapamycin-insensitive phosphorylation events identifies the S473 residue on Tripartite Motif-Containing 28 (TRIM28) as one of the most robust MIC-regulated phosphorylation sites, and extensive follow-up studies suggest that TRIM28 significantly contributes to the homeostatic regulation of muscle size and function as well as the hypertrophy that occurs in response to increased mechanical loading.
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Affiliation(s)
- Nathaniel D Steinert
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA; School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Gregory K Potts
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Gary M Wilson
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Amelia M Klamen
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA; School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Kuan-Hung Lin
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA; School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Jake B Hermanson
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA; School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Rachel M McNally
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA; School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Joshua J Coon
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA; Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, USA; Morgridge Institute for Research, Madison, WI, USA; Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA; School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA.
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Suginohara T, Wakabayashi K, Ato S, Ogasawara R. Effect of 2-deoxyglucose-mediated inhibition of glycolysis on the regulation of mTOR signaling and protein synthesis before and after high-intensity muscle contraction. Metabolism 2021; 114:154419. [PMID: 33161019 DOI: 10.1016/j.metabol.2020.154419] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Glycolysis controls mTORC1 signaling and protein synthesis. In skeletal muscle, glucose metabolism increases with both exercise/contraction intensity and volume, and therefore, high-intensity muscle contraction (HiMC) such as resistance exercise facilitates glycolysis including glucose uptake and glycogen breakdown. However, it is unknown whether glycolysis regulates HiMC-induced mTORC1 activation and increase in protein synthesis. METHODS To determine whether glycolysis regulates basal and HiMC-induced mTORC1 signaling and protein synthesis, we employed 2-deoxyglucose (2-DG) to inhibit glycolysis and isometrically contracted the gastrocnemius muscle of Sprague Dawley rats using percutaneous electrical stimulation. RESULTS Inhibition of glycolysis by 2-DG inhibited basal phosphorylation of p70S6K and 4E-BP1 (downstream targets of mTORC1) and protein synthesis (all P < 0.05) independent of AMPK phosphorylation. AMPK phosphorylation was comparably increased after HiMC at 0 h post HiMC and returned to basal levels 6 h post HiMC in both vehicle- and 2-DG-treated groups. Glycolysis inhibition attenuated muscle contraction-induced phosphorylation of 4E-BP1 at 6 h post HiMC (P < 0.05) but not p70S6K phosphorylation and protein synthesis. CONCLUSION Although glycolysis is involved in basal but not HiMC-induced muscle protein synthesis, it regulates both basal and HiMC-induced mTORC1 signaling, and may play key roles in skeletal muscle adaptation to HiMC.
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Affiliation(s)
- Takeshi Suginohara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Koki Wakabayashi
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Satoru Ato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan.
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Rindom E, Herskind J, Blaauw B, Overgaard K, Vissing K, Paoli FV. Concomitant excitation and tension development are required for myocellular gene expression and protein synthesis in rat skeletal muscle. Acta Physiol (Oxf) 2021; 231:e13540. [PMID: 32687678 DOI: 10.1111/apha.13540] [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: 12/20/2019] [Revised: 07/12/2020] [Accepted: 07/14/2020] [Indexed: 02/06/2023]
Abstract
AIM Loading-induced tension development is often assumed to constitute an independent cue to initiate muscle protein synthesis following resistance exercise. However, with traditional physiological models of resistance exercise, changes in loading-induced tension development also reflect changes in neural activation patterns, and direct evidence for a mechanosensitive mechanism is therefore limited. Here, we sought to examine the importance of excitation and tension development per se on initiation of signalling, gene transcription and protein synthesis in rat skeletal muscle. METHODS Isolated rat extensor digitorum longus muscles were allocated to the following interventions: (a) Excitation-induced eccentric contractions (ECC); (b) Passive stretching without excitation (PAS); (c) Excitation with inhibition of contractions (STIM + IMA ) and; (d) Excitation in combination with both inhibition of contractions and PAS (STIM + IMA + PAS). Assessment of transcriptional and translational signalling, gene transcription and acute muscle protein synthesis was compared in stimulated vs contra-lateral non-stimulated control muscle. RESULTS Protein synthesis increased solely in muscles subjected to a combination of excitation and tension development (ECC and STIM + IMA + PAS). The same pattern was true for p38 mitogen-activated protein kinase signalling for gene transcription as well as for gene transcription of immediate early genes FOS and JUN. In contrast, mechanistic target of rapamycin Complex 1 signalling for translation initiation increased in all muscles subjected to increased tension development (ECC and STIM + IMA + PAS as well as PAS). CONCLUSIONS The current study suggests that exercise-induced increases in protein synthesis as well as transcriptional signalling is dependent on the concomitant effect of excitation and tension development, whereas signalling for translation initiation is only dependent of tension development per se.
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Affiliation(s)
- Emil Rindom
- Department of Biomedicine Aarhus University Aarhus Denmark
| | - Jon Herskind
- Section for Sport Science Department of Public Health Aarhus University Aarhus Denmark
| | - Bert Blaauw
- Department of Biomedical Sciences University of Padova Padova Italy
| | - Kristian Overgaard
- Section for Sport Science Department of Public Health Aarhus University Aarhus Denmark
| | - Kristian Vissing
- Section for Sport Science Department of Public Health Aarhus University Aarhus Denmark
| | - Frank V. Paoli
- Department of Biomedicine Aarhus University Aarhus Denmark
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The Paradoxical Effect of PARP Inhibitor BGP-15 on Irinotecan-Induced Cachexia and Skeletal Muscle Dysfunction. Cancers (Basel) 2020; 12:cancers12123810. [PMID: 33348673 PMCID: PMC7766767 DOI: 10.3390/cancers12123810] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 12/14/2020] [Indexed: 12/24/2022] Open
Abstract
Simple Summary Both cancer and the chemotherapy used to treat it are drivers of cachexia, a life-threatening body-wasting condition which complicates cancer treatment. Poly-(ADP-ribose) polymerase (PARP) inhibitors are currently being investigated as a treatment against cancer. Here, we present paradoxical evidence that they might also be useful for mitigating the skeletal muscle specific side-effects of anti-cancer chemotherapy or exacerbate them. BGP-15 is a small molecule PARP inhibitor which protected against irinotecan (IRI)-induced cachexia and loss of skeletal muscle mass and dysfunction in our study. However, peculiarly, BGP-15 adjuvant therapy reduced protein synthesis rates and the expression of key cytoskeletal proteins associated with the dystrophin-associated protein complex and increased matrix metalloproteinase activity, while it increased the propensity for fast-twitch muscles to tear during fatiguing contraction. Our data suggest that both IRI and BGP-15 cause structural remodeling involving proteins associated with the contractile apparatus, cytoskeleton and/or the extracellular matrix which may be only transient and ultimately beneficial or may paradoxically onset a muscular dystrophy phenotype and be detrimental if more permanent. Abstract Chemotherapy-induced muscle wasting and dysfunction is a contributing factor to cachexia alongside cancer and increases the risk of morbidity and mortality. Here, we investigate the effects of the chemotherapeutic agent irinotecan (IRI) on skeletal muscle mass and function and whether BGP-15 (a poly-(ADP-ribose) polymerase-1 (PARP-1) inhibitor and heat shock protein co-inducer) adjuvant therapy could protect against IRI-induced skeletal myopathy. Healthy 6-week-old male Balb/C mice (n = 24; 8/group) were treated with six intraperitoneal injections of either vehicle, IRI (30 mg/kg) or BGP-15 adjuvant therapy (IRI+BGP; 15 mg/kg) over two weeks. IRI reduced lean and tibialis anterior mass, which were attenuated by IRI+BGP treatment. Remarkably, IRI reduced muscle protein synthesis, while IRI+BGP reduced protein synthesis further. These changes occurred in the absence of a change in crude markers of mammalian/mechanistic target of rapamycin (mTOR) Complex 1 (mTORC1) signaling and protein degradation. Interestingly, the cytoskeletal protein dystrophin was reduced in both IRI- and IRI+BGP-treated mice, while IRI+BGP treatment also decreased β-dystroglycan, suggesting significant remodeling of the cytoskeleton. IRI reduced absolute force production of the soleus and extensor digitorum longus (EDL) muscles, while IRI+BGP rescued absolute force production of the soleus and strongly trended to rescue force output of the EDL (p = 0.06), which was associated with improvements in mass. During the fatiguing stimulation, IRI+BGP-treated EDL muscles were somewhat susceptible to rupture at the musculotendinous junction, likely due to BGP-15’s capacity to maintain the rate of force development within a weakened environment characterized by significant structural remodeling. Our paradoxical data highlight that BGP-15 has some therapeutic advantage by attenuating IRI-induced skeletal myopathy; however, its effects on the remodeling of the cytoskeleton and extracellular matrix, which appear to make fast-twitch muscles more prone to tearing during contraction, could suggest the induction of muscular dystrophy and, thus, require further characterization.
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Scheuren AC, D'Hulst G, Kuhn GA, Masschelein E, Wehrle E, De Bock K, Müller R. Hallmarks of frailty and osteosarcopenia in prematurely aged PolgA (D257A/D257A) mice. J Cachexia Sarcopenia Muscle 2020; 11:1121-1140. [PMID: 32596975 PMCID: PMC7432580 DOI: 10.1002/jcsm.12588] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/14/2020] [Accepted: 02/24/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Frailty is a geriatric syndrome characterized by increased susceptibility to adverse health outcomes. One major determinant thereof is the gradual weakening of the musculoskeletal system and the associated osteosarcopenia. To improve our understanding of the underlying pathophysiology and, more importantly, to test potential interventions aimed at counteracting frailty, suitable animal models are needed. METHODS To evaluate the relevance of prematurely aged PolgA(D257A/D257A) mice as a model for frailty and osteosarcopenia, we quantified the clinical mouse frailty index in PolgA(D257A/D257A) and wild-type littermates (PolgA(+/+) , WT) with age and concertedly assessed the quantity and quality of bone and muscle tissue. Lastly, the anabolic responsiveness of skeletal muscle, muscle progenitors, and bone was assessed. RESULTS PolgA(D257A/D257A) accumulated health deficits at a higher rate compared with WT, resulting in a higher frailty index at 40 and 46 weeks of age (+166%, +278%, P < 0.0001), respectively, with no differences between genotypes at 34 weeks. Concomitantly, PolgA(D257A/D257A) displayed progressive musculoskeletal deterioration such as reduced bone and muscle mass as well as impaired functionality thereof. In addition to lower muscle weights (-14%, P < 0.05, -23%, P < 0.0001) and fibre area (-20%, P < 0.05, -22%, P < 0.0001) at 40 and 46 weeks, respectively, PolgA(D257A/D257A) showed impairments in grip strength and concentric muscle forces (P < 0.05). PolgA(D257A/D257A) mutation altered the acute response to various anabolic stimuli in skeletal muscle and muscle progenitors. While PolgA(D257A/D257A) muscles were hypersensitive to eccentric contractions as well as leucine administration, shown by larger downstream signalling response of the mechanistic target of rapamycin complex 1, myogenic progenitors cultured in vitro showed severe anabolic resistance to leucine and robust impairments in cell proliferation. Longitudinal micro-computed tomography analysis of the sixth caudal vertebrae showed that PolgA(D257A/D257A) had lower bone morphometric parameters (e.g. bone volume fraction, trabecular, and cortical thickness, P < 0.05) as well as reduced remodelling activities (e.g. bone formation and resorption rate, P < 0.05) compared with WT. When subjected to 4 weeks of cyclic loading, young but not aged PolgA(D257A/D257A) caudal vertebrae showed load-induced bone adaptation, suggesting reduced mechanosensitivity with age. CONCLUSIONS PolgA(D257A/D257A) mutation leads to hallmarks of age-related frailty and osteosarcopenia and provides a powerful model to better understand the relationship between frailty and the aging musculoskeletal system.
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Affiliation(s)
| | - Gommaar D'Hulst
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | | | - Evi Masschelein
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | - Esther Wehrle
- Institute for BiomechanicsETH ZurichZurichSwitzerland
| | - Katrien De Bock
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | - Ralph Müller
- Institute for BiomechanicsETH ZurichZurichSwitzerland
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Komorowski JR, Ojalvo SP, Sylla S, Tastan H, Orhan C, Tuzcu M, Sahin N, Sahin K. The addition of an amylopectin/chromium complex to branched-chain amino acids enhances muscle protein synthesis in rat skeletal muscle. J Int Soc Sports Nutr 2020; 17:26. [PMID: 32460884 PMCID: PMC7251890 DOI: 10.1186/s12970-020-00355-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 05/10/2020] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND A previous clinical study reported that the addition of an amylopectin/chromium complex (ACr; Velositol®) to 6 g of whey protein (WP) significantly enhanced muscle protein synthesis (MPS). Branched-chain amino acids (BCAAs) are also well-known to enhance MPS. The aim of this study was to determine if the addition of ACr to BCAAs can enhance MPS and activate expression of the mammalian target of the rapamycin (mTOR) pathway compared to BCAAs and exercise alone in exercise-trained rats. METHODS Twenty-four male Wistar rats were randomly divided into three groups (n = 8 per group): (I) Exercise control, (II) Exercise plus BCAAs (0.465 g/kg BW, a 6 g human equivalent dose (HED)), and (III) Exercise plus BCAAs (0.465 g/kg BW) and ACr (0.155 g/kg BW, a 2 g HED). All animals were trained with treadmill exercise for 10 days. On the day of the single-dose experiment, rats were exercised at 26 m/min for 2 h and then fed, via oral gavage, study product. One hour after the consumption of study product, rats were injected with a bolus dose (250 mg/kg BW, 25 g/L) of phenylalanine labeled with deuterium to measure the fractional rate of protein synthesis (FSR). Ten minutes later, muscle tissue samples were taken to determine MPS measured by FSR and the phosphorylation of proteins involved in the mTOR pathway including mTOR, S6K1, and 4E-BP1. RESULTS ACr combined with BCAAs increased MPS by 71% compared to the exercise control group, while BCAAs alone increased MPS by 57% over control (p < 0.05). ACr plus BCAAs significantly enhanced phosphorylation of mTOR, S6K1 and 4E-BP1 compared to exercise control rats (p < 0.05). The addition of ACr to BCAAs enhanced insulin levels, mTOR and S6K1 phosphorylation compared to BCAAs alone (p < 0.05). Serum insulin concentration was positively correlated with the levels of mTOR, (r = 0.923), S6K1 (r = 0.814) and 4E-BP1 (r = 0.953). CONCLUSIONS In conclusion, the results of this study provide evidence that the addition of ACr to BCAAs significantly enhances exercise-induced MPS, and the phosphorylation of mTOR signaling proteins, compared to BCAAs and exercise alone.
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Affiliation(s)
- James R Komorowski
- Research and Development Department, Nutrition 21 LLC, Purchase, NY, 10577, USA.
| | - Sara Perez Ojalvo
- Research and Development Department, Nutrition 21 LLC, Purchase, NY, 10577, USA
| | - Sarah Sylla
- Research and Development Department, Nutrition 21 LLC, Purchase, NY, 10577, USA
| | - Hakki Tastan
- Division of Biology, Faculty of Science, Gazi University, 06100, Ankara, Turkey
| | - Cemal Orhan
- Department of Animal Nutrition and Nutritional Disorders, Faculty of Veterinary Medicine, Firat University, 23119, Elazig, Turkey
| | - Mehmet Tuzcu
- Division of Biology, Faculty of Science, Firat University, 23119, Elazig, Turkey
| | - Nurhan Sahin
- Department of Animal Nutrition and Nutritional Disorders, Faculty of Veterinary Medicine, Firat University, 23119, Elazig, Turkey
| | - Kazim Sahin
- Department of Animal Nutrition and Nutritional Disorders, Faculty of Veterinary Medicine, Firat University, 23119, Elazig, Turkey
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Ato S, Kido K, Sase K, Fujita S. Response of Resistance Exercise-Induced Muscle Protein Synthesis and Skeletal Muscle Hypertrophy Are Not Enhanced After Disuse Muscle Atrophy in Rat. Front Physiol 2020; 11:469. [PMID: 32528306 PMCID: PMC7258402 DOI: 10.3389/fphys.2020.00469] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/16/2020] [Indexed: 01/26/2023] Open
Abstract
Skeletal muscle disuse rapidly decreases muscle mass. Resistance training (RT) is believed as the most effective way to gain muscle mass via an increase in mTORC1 activity and muscle protein synthesis (MPS). However, it remains unclear whether muscle atrophy by disuse alters the mTORC1 activation and MPS response to an acute resistance exercise (RE) and chronic RT-mediated skeletal muscle hypertrophy. This study investigated the influence of disuse muscle atrophy on the response of mTORC1 activation and MPS to an acute RE. We also evaluated whether disuse muscle atrophy affects the response of RT-induced muscle mass gain. Thirty male Sprague-Dawley rats were randomly divided into control (CON) or hindlimb suspension (HS) groups. A 14-day HS via the tail was used as the model for gastrocnemius muscle disuse in the HS group. Unilateral lower limb muscle contraction using by percutaneous electrical stimulation was used to mimic the stimuli of RE. Ten bouts of RE were performed in 3-week as chronic RT. Our results showed that MPS and mTORC1 activity was unchanged after HS at basal state. However, the ribosomal RNA (rRNA) level was reduced in HS rats compared to that in CON rats at basal state. MPS and rRNA increased in both HS and CON rats in response to acute RE to the same extent. However, the level of mTORC1 activation in response to an acute RE was significantly higher in HS than that in the CON group at 12 h after exercise, even though no difference was observed at 3 h after exercise. The 10-bout RT significantly increased gastrocnemius muscle mass in both CON and HS rats. The response of muscle hypertrophy did not differ between the groups. Therefore, MPS in response to acute RE and muscle hypertrophy in response to chronic RT were unaltered after disuse muscle atrophy.
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Affiliation(s)
- Satoru Ato
- Graduate School of Sport and Health Science, Ritsumeikan University, Shiga, Japan.,Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Kohei Kido
- Graduate School of Sport and Health Science, Ritsumeikan University, Shiga, Japan.,Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
| | - Kohei Sase
- Graduate School of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Satoshi Fujita
- Graduate School of Sport and Health Science, Ritsumeikan University, Shiga, Japan
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A focused review of myokines as a potential contributor to muscle hypertrophy from resistance-based exercise. Eur J Appl Physiol 2020; 120:941-959. [PMID: 32144492 DOI: 10.1007/s00421-020-04337-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 02/27/2020] [Indexed: 02/07/2023]
Abstract
PURPOSE Resistance exercise induces muscle growth and is an important treatment for age-related losses in muscle mass and strength. Myokines are hypothesized as a signal conveying physiological information to skeletal muscle, possibly to "fine-tune" other regulatory pathways. While myokines are released from skeletal muscle following contraction, their role in increasing muscle mass and strength in response to resistance exercise or training is not established. Recent research identified both local and systemic release of myokines after an acute bout of resistance exercise. However, it is not known whether myokines with putative anabolic function are mechanistically involved in producing muscle hypertrophy after resistance exercise. Further, nitric oxide (NO), an important mediator of muscle stem cell activation, upregulates the expression of certain myokine genes in skeletal muscle. METHOD In the systemic context of complex hypertrophic signaling, this review: (1) summarizes literature on several well-recognized, representative myokines with anabolic potential; (2) explores the potential mechanistic role of myokines in skeletal muscle hypertrophy; and (3) identifies future research required to advance our understanding of myokine anabolism specifically in skeletal muscle. RESULT This review establishes a link between myokines and NO production, and emphasizes the importance of considering systemic release of potential anabolic myokines during resistance exercise as complementary to other signals that promote hypertrophy. CONCLUSION Investigating adaptations to resistance exercise in aging opens a novel avenue of interdisciplinary research into myokines and NO metabolites during resistance exercise, with the longer-term goal to improve muscle health in daily living, aging, and rehabilitation.
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30
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Ato S, Maruyama Y, Yoshizato H, Ogasawara R. Habitual high-protein diet does not influence muscle protein synthesis in response to acute resistance exercise in rats. Nutrition 2020; 78:110795. [PMID: 32480256 DOI: 10.1016/j.nut.2020.110795] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/17/2020] [Accepted: 01/23/2020] [Indexed: 01/28/2023]
Abstract
OBJECTIVES Resistance training combined with consumption of a high-protein diet (HPD) is typically recommended to increase muscle mass, as both acute resistance exercise (RE) and dietary protein intake stimulate mechanistic target of rapamycin complex 1 (mTORC1) and muscle protein synthesis (MPS). However, the effect of chronic HPD consumption on MPS response to an acute RE remains to be determined. METHODS Male Sprague-Dawley rats aged 10 wk were fed HPD (50 kcal % protein, for 4 wk) or normal protein diet (NPD; 20 kcal % protein). After the 4-wk dietary intervention, the rats were fasted overnight and the right gastrocnemius muscle was subjected to percutaneous electrical stimulation to mimic acute RE, whereas the left gastrocnemius muscle served as control. The rats were sacrificed 6 h after exercise and the tissues were sampled immediately. RESULTS The HPD group showed significantly lower fat mass and higher skeletal muscle mass than the NPD group without affecting body weight. Resting mTORC1 activity did not differ between the groups. Additionally, resting MPS was also unchanged after HPD. Acute RE significantly increased mTORC1 activity and MPS in both groups. However, differences in diet did not influence the response of mTORC1 activation to acute RE. Furthermore, HPD did not affect the response of MPS to acute RE. CONCLUSION The present results suggested that although 4 wk of HPD reduces body fat and increases skeletal muscle mass, it does not affect muscle protein synthesis at basal state, and in response to acute RE.
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Affiliation(s)
- Satoru Ato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Yuki Maruyama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Hideo Yoshizato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan.
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Abstract
PURPOSE OF REVIEW Skeletal muscle wasting during critical illness is the result of disturbed metabolism. No proven effective interventions targeting skeletal muscle mass and function during critical illness currently exist. This review summarizes recent advances regarding the complexity of metabolic factors involved and the challenge of establishing the clinical effects of metabolic interventions targeting the muscle. RECENT FINDINGS Although the catabolic state is limited to the acute phase of critical illness, its subsequent impact on muscle mass and function persists long after ICU discharge. Immobilization, inflammation and disturbed muscle energy and nutrient metabolism are key drivers of muscle protein loss. Current research focuses on the effects of enhanced protein provision, specific substrate delivery and physical exercise. Whilst some interventions have been successful at improving muscle mass, these effects do not always carry over into muscle function or strength. SUMMARY Increased understanding of metabolic derangements during critical illness provides new potential targets for treatment. The potential of dietary protein to attenuate the muscle protein catabolic state has yet to be established in clinical trials. Basic research should focus on ways to further improve the anabolic potential of nutrition by unravelling mechanisms that regulate anabolic and catabolic pathways and energy metabolism.
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Affiliation(s)
- Robert J.J. van Gassel
- Department of Intensive Care Medicine
- Department of Surgery, Maastricht University Medical Centre and NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, The Netherlands
| | | | - Marcel C.G. van de Poll
- Department of Intensive Care Medicine
- Department of Surgery, Maastricht University Medical Centre and NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, The Netherlands
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Henriquez-Olguin C, Meneses-Valdes R, Jensen TE. Compartmentalized muscle redox signals controlling exercise metabolism - Current state, future challenges. Redox Biol 2020; 35:101473. [PMID: 32122793 PMCID: PMC7284909 DOI: 10.1016/j.redox.2020.101473] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 02/07/2023] Open
Abstract
Exercise imposes cellular stress on contracting skeletal muscle fibers, forcing them to complete molecular adaptations to maintain homeostasis. There is mounting evidence that redox signaling by reactive oxygen species (ROS) is vital for skeletal muscle exercise adaptations across many different exercise modalities. The study of redox signaling is moving towards a growing appreciation that these ROS do not signal in a global unspecific way, but rather elicit their effects in distinct subcellular compartments. This short review will first outline the sources of ROS in exercising skeletal muscle and then discuss some examples of exercise adaptations, which are evidenced to be regulated by compartmentalized redox signaling. We speculate that knowledge of these redox pathways might one day allow targeted manipulation to increase redox-signaling in specific compartments to augment the exercise-hormetic response in health and disease.
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Affiliation(s)
- Carlos Henriquez-Olguin
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Roberto Meneses-Valdes
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark; Integrated Physiology Unit, Laboratory of Exercise Sciences, MEDS Clinic, Santiago, Chile
| | - Thomas E Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise, and Sports (NEXS), Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
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D'Hulst G, Soro-Arnaiz I, Masschelein E, Veys K, Fitzgerald G, Smeuninx B, Kim S, Deldicque L, Blaauw B, Carmeliet P, Breen L, Koivunen P, Zhao SM, De Bock K. PHD1 controls muscle mTORC1 in a hydroxylation-independent manner by stabilizing leucyl tRNA synthetase. Nat Commun 2020; 11:174. [PMID: 31924757 PMCID: PMC6954236 DOI: 10.1038/s41467-019-13889-6] [Citation(s) in RCA: 274] [Impact Index Per Article: 68.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 12/06/2019] [Indexed: 02/08/2023] Open
Abstract
mTORC1 is an important regulator of muscle mass but how it is modulated by oxygen and nutrients is not completely understood. We show that loss of the prolyl hydroxylase domain isoform 1 oxygen sensor in mice (PHD1KO) reduces muscle mass. PHD1KO muscles show impaired mTORC1 activation in response to leucine whereas mTORC1 activation by growth factors or eccentric contractions was preserved. The ability of PHD1 to promote mTORC1 activity is independent of its hydroxylation activity but is caused by decreased protein content of the leucyl tRNA synthetase (LRS) leucine sensor. Mechanistically, PHD1 interacts with and stabilizes LRS. This interaction is promoted during oxygen and amino acid depletion and protects LRS from degradation. Finally, elderly subjects have lower PHD1 levels and LRS activity in muscle from aged versus young human subjects. In conclusion, PHD1 ensures an optimal mTORC1 response to leucine after episodes of metabolic scarcity. mTORC1 is an important regulator of muscle mass. Here, the authors show that the PHD1 controls muscle mass in a hydroxylation-independent manner. PHD1 prevents the degradation of leucine sensor LRS during oxygen and amino acid depletion to ensure effective mTORC1 activation in response to leucine.
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Affiliation(s)
- Gommaar D'Hulst
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Inés Soro-Arnaiz
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Evi Masschelein
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Koen Veys
- Laboratory of Angiogenesis and Vascular Metabolism, VIB Center for Cancer Biology (CCB), VIB, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium
| | - Gillian Fitzgerald
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Benoit Smeuninx
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.,MRC Arthritis Research UK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Sunghoon Kim
- Medicinal Bioconvergence Research Center, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul, South Korea
| | - Louise Deldicque
- Institute of Neuroscience, Université catholique de Louvain, Louvain-La-Neuve, Belgium
| | - Bert Blaauw
- Department of Biomedical Sciences, Venetian Institute of Molecular Medicine, University of Padova, Padova, Italy
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Vascular Metabolism, VIB Center for Cancer Biology (CCB), VIB, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium
| | - Leigh Breen
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.,MRC Arthritis Research UK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Peppi Koivunen
- Biocenter Oulu, Faculty of Biochemistry and Molecular Medicine, Oulu Center for Cell-Matrix Research, University of Oulu, Oulu, Finland
| | - Shi-Min Zhao
- Obstetrics and Gynaecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Shanghai, P. R. China.,Institute of Biomedical Science, Fudan University, Shanghai, P. R. China.,Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, P. R. China
| | - Katrien De Bock
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland.
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