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Fennel ZJ, Ducharme JB, Berkemeier QN, Specht JW, McKenna ZJ, Simpson SE, Nava RC, Escobar KA, Hafen PS, Deyhle MR, Amorim FT, Mermier CM. Effect of heat stress on heat shock protein expression and hypertrophy-related signaling in the skeletal muscle of trained individuals. Am J Physiol Regul Integr Comp Physiol 2023; 325:R735-R749. [PMID: 37842742 DOI: 10.1152/ajpregu.00031.2023] [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: 01/30/2023] [Revised: 10/04/2023] [Accepted: 10/05/2023] [Indexed: 10/17/2023]
Abstract
Muscle mass is balanced between hypertrophy and atrophy by cellular processes, including activation of the protein kinase B-mechanistic target of rapamycin (Akt-mTOR) signaling cascade. Stressors apart from exercise and nutrition, such as heat stress, can stimulate the heat shock protein A (HSPA) and C (HSPC) families alongside hypertrophic signaling factors and muscle growth. The effects of heat stress on HSP expression and Akt-mTOR activation in human skeletal muscle and their magnitude of activation compared with known hypertrophic stimuli are unclear. Here, we show a single session of whole body heat stress following resistance exercise increases the expression of HSPA and activation of the Akt-mTOR cascade in skeletal muscle compared with resistance exercise in a healthy, resistance-trained population. Heat stress alone may also exert similar effects, though the responses are notably variable and require further investigation. In addition, acute heat stress in C2C12 muscle cells enhanced myotube growth and myogenic fusion, albeit to a lesser degree than growth factor-mediated hypertrophy. Though the mechanisms by which heat stress stimulates hypertrophy-related signaling and the potential mechanistic role of HSPs remain unclear, these findings provide additional evidence implicating heat stress as a novel growth stimulus when combined with resistance exercise in human skeletal muscle and alone in isolated murine muscle cells. We believe these findings will help drive further applied and mechanistic investigation into how heat stress influences muscular hypertrophy and atrophy.NEW & NOTEWORTHY We show that acute resistance exercise followed by whole body heat stress increases the expression of HSPA and increases activation of the Akt-mTOR cascade in a physically active and resistance-trained population.
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Affiliation(s)
- Zachary J Fennel
- Department of Health, Exercise & Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, United States
| | - Jeremy B Ducharme
- Department of Health, Exercise & Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
| | - Quint N Berkemeier
- Department of Health, Exercise & Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
| | - Jonathan W Specht
- Department of Health, Exercise & Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
| | - Zachary J McKenna
- Department of Health, Exercise & Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
- Institute for Exercise and Environmental Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Shandy E Simpson
- Department of Health, Exercise & Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
| | - Roberto C Nava
- Fulcrum Therapeutics, Cambridge, Massachusetts, United States
| | - Kurt A Escobar
- Department of Kinesiology, California State University Long Beach, Long Beach, California, United States
| | - Paul S Hafen
- Division of Science, Indiana University Purdue University Columbus, Columbus, Indiana, United States
- Department of Anatomy, Cell Biology, and Physiology, Indiana Center for Musculoskeletal Health, Indiana University School of Medicine Indianapolis, Indianapolis, Indiana, United States
| | - Michael R Deyhle
- Department of Health, Exercise & Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
- Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico, United States
| | - Fabiano T Amorim
- Department of Health, Exercise & Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
| | - Christine M Mermier
- Department of Health, Exercise & Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
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2
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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: 7] [Impact Index Per Article: 7.0] [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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3
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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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4
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Shaiken TE, Grimm SL, Siam M, Williams A, Rezaeian AH, Kraushaar D, Ricco E, Robertson MJ, Coarfa C, Jain A, Malovannaya A, Stossi F, Opekun AR, Price AP, Dubrulle J. Transcriptome, proteome, and protein synthesis within the intracellular cytomatrix. iScience 2023; 26:105965. [PMID: 36824274 PMCID: PMC9941065 DOI: 10.1016/j.isci.2023.105965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 11/07/2022] [Accepted: 01/06/2023] [Indexed: 01/15/2023] Open
Abstract
Despite the knowledge that protein translation and various metabolic reactions that create and sustain cellular life occur in the cytoplasm, the structural organization within the cytoplasm remains unclear. Recent models indicate that cytoplasm contains viscous fluid and elastic solid phases. We separated these viscous fluid and solid elastic compartments, which we call the cytosol and cytomatrix, respectively. The distinctive composition of the cytomatrix included structural proteins, ribosomes, and metabolome enzymes. High-throughput analysis revealed unique biosynthetic pathways within the cytomatrix. Enrichment of biosynthetic pathways in the cytomatrix indicated the presence of immobilized biocatalysis. Enzymatic immobilization and segregation can surmount spatial impediments, and the local pathway segregation may form cytoplasmic organelles. Protein translation was reprogrammed within the cytomatrix under the restriction of protein synthesis by drug treatment. The cytosol and cytomatrix are an elaborately interconnected network that promotes operational flexibility in healthy cells and the survival of malignant cells.
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Affiliation(s)
- Tattym E. Shaiken
- Department of Medicine-Gastroenterology and Hepatology Section, Michael E DeBakey Veteran’s Affairs Medical Center, Baylor College of Medicine, Houston, TX 77030, USA
- PeriNuc Labs, University of Houston Technology Bridge, Houston, TX 77023, USA
| | - Sandra L. Grimm
- Advanced Technology Cores, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mohamad Siam
- Department of Medicine-Gastroenterology and Hepatology Section, Michael E DeBakey Veteran’s Affairs Medical Center, Baylor College of Medicine, Houston, TX 77030, USA
- PeriNuc Labs, University of Houston Technology Bridge, Houston, TX 77023, USA
| | - Amanda Williams
- Department of Medicine-Gastroenterology and Hepatology Section, Michael E DeBakey Veteran’s Affairs Medical Center, Baylor College of Medicine, Houston, TX 77030, USA
- PeriNuc Labs, University of Houston Technology Bridge, Houston, TX 77023, USA
| | - Abdol-Hossein Rezaeian
- PeriNuc Labs, University of Houston Technology Bridge, Houston, TX 77023, USA
- Department of Drug Discovery and Biomedical Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Daniel Kraushaar
- Advanced Technology Cores, Baylor College of Medicine, Houston, TX 77030, USA
| | - Emily Ricco
- Advanced Technology Cores, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Cristian Coarfa
- Advanced Technology Cores, Baylor College of Medicine, Houston, TX 77030, USA
| | - Antrix Jain
- Advanced Technology Cores, Baylor College of Medicine, Houston, TX 77030, USA
| | - Anna Malovannaya
- Advanced Technology Cores, Baylor College of Medicine, Houston, TX 77030, USA
| | - Fabio Stossi
- Advanced Technology Cores, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Antone R. Opekun
- Department of Medicine-Gastroenterology and Hepatology Section, Michael E DeBakey Veteran’s Affairs Medical Center, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Alyssa P. Price
- Department of Medicine-Gastroenterology and Hepatology Section, Michael E DeBakey Veteran’s Affairs Medical Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Julien Dubrulle
- Advanced Technology Cores, Baylor College of Medicine, Houston, TX 77030, USA
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Tinline-Goodfellow CT, Lees MJ, Hodson N. The skeletal muscle fiber periphery: A nexus of mTOR-related anabolism. SPORTS MEDICINE AND HEALTH SCIENCE 2022; 5:10-19. [PMID: 36994172 PMCID: PMC10040390 DOI: 10.1016/j.smhs.2022.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/16/2022] [Accepted: 11/23/2022] [Indexed: 12/02/2022] Open
Abstract
Skeletal muscle anabolism is driven by numerous stimuli such as growth factors, nutrients (i.e., amino acids, glucose), and mechanical stress. These stimuli are integrated by the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) signal transduction cascade. In recent years, work from our laboratory and elsewhere has sought to unravel the molecular mechanisms underpinning the mTOR-related activation of muscle protein synthesis (MPS), as well as the spatial regulation of these mechanisms within the skeletal muscle cell. These studies have suggested that the skeletal muscle fiber periphery is a region of central importance in anabolism (i.e., growth/MPS). Indeed, the fiber periphery is replete with the substrates, molecular machinery, and translational apparatus necessary to facilitate MPS. This review provides a summary of the mechanisms underpinning the mTOR-associated activation of MPS from cell, rodent, and human studies. It also presents an overview of the spatial regulation of mTORC1 in response to anabolic stimuli and outlines the factors that distinguish the periphery of the cell as a highly notable region of skeletal muscle for the induction of MPS. Future research should seek to further explore the nutrient-induced activation of mTORC1 at the periphery of skeletal muscle fibers.
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Affiliation(s)
| | - Matthew J. Lees
- Faculty of Kinesiology and Physical Education, University of Toronto, Canada
| | - Nathan Hodson
- Faculty of Kinesiology and Physical Education, University of Toronto, Canada
- Institute of Sport, Manchester Metropolitan University, Manchester, United Kingdom
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
- Corresponding author. Faculty of Kinesiology and Physical Education, University of Toronto, Canada.
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6
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Lee S, Kim JS, Park KS, Baek KW, Yoo JI. Daily Walking Accompanied with Intermittent Resistance Exercise Prevents Osteosarcopenia: A Large Cohort Study. J Bone Metab 2022; 29:255-263. [PMID: 36529868 PMCID: PMC9760770 DOI: 10.11005/jbm.2022.29.4.255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/05/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND This study aimed to analyze the effects of walking and resistance exercises on bone structure, bone mineral density (BMD), and skeletal muscle mass. We used data from the fourth Korean National Health and Nutrition Examination Survey (KNHANES). METHODS A total of 3,477 participants aged ≥19 years underwent hip structural analysis (HSA), BMD, and skeletal muscle index (SMI). All radiologic evaluations were performed using dual energy X-ray absorptiometry (DXA). The Korean short version of the International Physical Activity Questionnaire was used to measure physical activity status. The physical activity recommendations of the American College of Rheumatology Work Group Panel were used to evaluate the extent of activity. RESULTS The BMD and SMI in the group in which walking activity was performed 5 days or more per week for at least 30 min per day were significantly higher than those in the group in which walking activity was not performed. HSA and SMI in the group in which resistance exercise was performed 2 days or more per week for at least 30 min per day were found to be significantly higher than those in the group in which strengthening exercises were not performed. CONCLUSIONS If resistance exercise and walking are combined, bone loss and muscle loss are prevented maintaining cortical thickness in the elderly. Walking for more than 5 days a week and resistance exercise for more than 2 days a week will help to maintain the skeletal muscle as well as the cortex around the femur neck, thus helping to prevent fragility fractures in older individuals.
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Affiliation(s)
- Sangyeob Lee
- Department of Biomedical Research Institute, Gyeongsang National University Hospital, Jinju,
Korea
| | - Ji-Seok Kim
- Department of Physical Education, Gyeongsang National University, Jinju,
Korea
| | - Ki-Soo Park
- Department of Preventive Medicine and Institute of Health Sciences, Gyeongsang National University, Jinju,
Korea
| | - Kyung-Wan Baek
- Department of Physical Education, Gyeongsang National University, Jinju,
Korea
| | - Jun-Il Yoo
- Department of Orthopaedic Surgery, Gyeongang National University Hospital, Gyeongsang National University, Jinju,
Korea
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7
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Lunin SM, Novoselova EG, Glushkova OV, Parfenyuk SB, Novoselova TV, Khrenov MO. Cell Senescence and Central Regulators of Immune Response. Int J Mol Sci 2022; 23:ijms23084109. [PMID: 35456927 PMCID: PMC9028919 DOI: 10.3390/ijms23084109] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/04/2022] [Accepted: 04/06/2022] [Indexed: 12/13/2022] Open
Abstract
Pathways regulating cell senescence and cell cycle underlie many processes associated with ageing and age-related pathologies, and they also mediate cellular responses to exposure to stressors. Meanwhile, there are central mechanisms of the regulation of stress responses that induce/enhance or weaken the response of the whole organism, such as hormones of the hypothalamic-pituitary-adrenal (HPA) axis, sympathetic and parasympathetic systems, thymic hormones, and the pineal hormone melatonin. Although there are many analyses considering relationships between the HPA axis and organism ageing, we found no systematic analyses of relationships between the neuroendocrine regulators of stress and inflammation and intracellular mechanisms controlling cell cycle, senescence, and apoptosis. Here, we provide a review of the effects of neuroendocrine regulators on these mechanisms. Our analysis allowed us to postulate a multilevel system of central regulators involving neurotransmitters, glucocorticoids, melatonin, and the thymic hormones. This system finely regulates the cell cycle and metabolic/catabolic processes depending on the level of systemic stress, stage of stress response, and energy capabilities of the body, shifting the balance between cell cycle progression, cell cycle stopping, senescence, and apoptosis. These processes and levels of regulation should be considered when studying the mechanisms of ageing and the proliferation on the level of the whole organism.
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8
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Attwaters M, Hughes SM. Cellular and molecular pathways controlling muscle size in response to exercise. FEBS J 2022; 289:1428-1456. [PMID: 33755332 DOI: 10.1111/febs.15820] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 02/27/2021] [Accepted: 03/12/2021] [Indexed: 12/14/2022]
Abstract
From the discovery of ATP and motor proteins to synaptic neurotransmitters and growth factor control of cell differentiation, skeletal muscle has provided an extreme model system in which to understand aspects of tissue function. Muscle is one of the few tissues that can undergo both increase and decrease in size during everyday life. Muscle size depends on its contractile activity, but the precise cellular and molecular pathway(s) by which the activity stimulus influences muscle size and strength remain unclear. Four correlates of muscle contraction could, in theory, regulate muscle growth: nerve-derived signals, cytoplasmic calcium dynamics, the rate of ATP consumption and physical force. Here, we summarise the evidence for and against each stimulus and what is known or remains unclear concerning their molecular signal transduction pathways and cellular effects. Skeletal muscle can grow in three ways, by generation of new syncytial fibres, addition of nuclei from muscle stem cells to existing fibres or increase in cytoplasmic volume/nucleus. Evidence suggests the latter two processes contribute to exercise-induced growth. Fibre growth requires increase in sarcolemmal surface area and cytoplasmic volume at different rates. It has long been known that high-force exercise is a particularly effective growth stimulus, but how this stimulus is sensed and drives coordinated growth that is appropriately scaled across organelles remains a mystery.
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Affiliation(s)
- Michael Attwaters
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, UK
| | - Simon M Hughes
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, UK
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9
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Kotani T, Takegaki J, Tamura Y, Kouzaki K, Nakazato K, Ishii N. The effect of repeated bouts of electrical stimulation-induced muscle contractions on proteolytic signaling in rat skeletal muscle. Physiol Rep 2021; 9:e14842. [PMID: 33991444 PMCID: PMC8123562 DOI: 10.14814/phy2.14842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 03/16/2021] [Indexed: 11/24/2022] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) plays a central role in muscle protein synthesis and repeated bouts of resistance exercise (RE) blunt mTORC1 activation. However, the changes in the proteolytic signaling when recurrent RE bouts attenuate mTORC1 activation are unclear. Using a RE model of electrically stimulated rat skeletal muscle, this study aimed to clarify the effect of repeated RE bouts on acute proteolytic signaling, particularly the calpain, autophagy‐lysosome, and ubiquitin‐proteasome pathway. p70S6K and rpS6 phosphorylation, indicators of mTORC1 activity, were attenuated by repeated RE bouts. Calpain 3 protein was decreased at 6 h post‐RE in all exercised groups regardless of the bout number. Microtubule‐associated protein 1 light chain 3 beta‐II, an indicator of autophagosome formation, was increased at 3 h and repeated RE bouts increased at 6 h, post‐RE. Ubiquitinated proteins were increased following RE, but these increases were independent of the number of RE bouts. These results suggest that the magnitude of autophagosome formation was increased following RE when mTORC1 activity was attenuated with repeated bouts of RE.
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Affiliation(s)
- Takaya Kotani
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.,Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan
| | - Junya Takegaki
- Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, Shiga, Japan
| | - Yuki Tamura
- Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan
| | - Karina Kouzaki
- 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
| | - Naokata Ishii
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
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10
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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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11
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El-Kadi SW, Boutry-Regard C, Suryawan A, Nguyen HV, Kimball SR, Fiorotto ML, Davis TA. Intermittent Bolus Feeding Enhances Organ Growth More Than Continuous Feeding in a Neonatal Piglet Model. Curr Dev Nutr 2020; 4:nzaa170. [PMID: 33381676 PMCID: PMC7751947 DOI: 10.1093/cdn/nzaa170] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/06/2020] [Accepted: 11/13/2020] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Orogastric tube feeding is frequently prescribed for neonates who cannot ingest food normally. In a piglet model of the neonate, greater skeletal muscle growth is sustained by upregulation of translation initiation signaling when nutrition is delivered by intermittent bolus meals, rather than continuously. OBJECTIVES The objective of this study was to determine the long-term effects of feeding frequency on organ growth and the mechanism by which feeding frequency modulates protein anabolism in these organs. METHODS Eighteen neonatal pigs were fed by gastrostomy tube the same amount of a sow milk replacer either by continuous infusion (CON) or on an intermittent bolus schedule (INT). After 21 d of feeding, the pigs were killed without interruption of feeding (CON; n = 6) or immediately before (INT-0; n = 6) or 60 min after (INT-60; n = 6) a meal, and fractional protein synthesis rates and activation indexes of signaling pathways that regulate translation initiation were measured in the heart, jejunum, ileum, kidneys, and liver. RESULTS Compared with continuous feeding, intermittent feeding stimulated the growth of the liver (+64%), jejunum (+48%), ileum (+40%), heart (+64%), and kidney (+56%). The increases in heart, kidney, jejunum, and ileum masses were proportional to whole body lean weight gain, but liver weight gain was greater in the INT-60 than the CON, and intermediate for the INT-0 group. For the liver and ileum, but not the heart, kidney, and jejunum, INT-60 compared with CON pigs had greater fractional protein synthesis rates (22% and 48%, respectively) and was accompanied by an increase in ribosomal protein S6 kinase 1 and eukaryotic initiation factor 4E binding protein 1 phosphorylation. CONCLUSIONS These results suggest that intermittent bolus compared with continuous orogastric feeding enhances organ growth and that in the ileum and liver, intermittent feeding enhances protein synthesis by stimulating translation initiation.
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Affiliation(s)
- Samer W El-Kadi
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA, USA
| | - Claire Boutry-Regard
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Agus Suryawan
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Hanh V Nguyen
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Marta L Fiorotto
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Teresa A Davis
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
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12
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Lin CY, Hou CY, Tsai CM, Chang H. Muscle type from which satellite cells are derived plays a role in their damage response. CHINESE J PHYSIOL 2020; 63:113-121. [PMID: 32594064 DOI: 10.4103/cjp.cjp_98_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The aim of this study was to evaluate the response of satellite cells to muscular atrophies which possess different pathological characteristics and which were induced by distinct damages. Right lower limbs of rats were exposed to denervation or disuse and later its tibialis anterior (TA) or soleus (SOL) muscles were analyzed. After confirming their functional impairments indicated by common but distinct pathological and electrophysiological characteristics, the quantitative polymerase chain reaction analysis of Pax7 and Pax3 expressions and the number of Pax7+ve and Pax3+ve cells were analyzed sequentially at day 0, day 7, and day 14. TA muscles of both denervation- and disuse-induced atrophy models showed persisted low level of Pax7 expression from day 7 (0.91 ± 0.23 and 0.31 ± 0.07, P = 0.06, n = 6) through day 14 (1.09 ± 0.15 and 0.4 ± 0.09 [P < 0.05]). On the other hand, significant elevations were observed in Pax3 expression in both atrophy models (2.73 ± 0.46 and 2.75 ± 0.26 [P < 0.05]) at day 7. Similar to TA muscle, resembled pattern of Pax7 and Pax3 expression changes were observed between the SOL muscles of denervation- and disused-atrophy models. These trends were further confirmed by the changes in Pax7+ve and Pax3+ve cell numbers of TA and SOL muscles in both atrophy models. Despite the distinct pathological findings, similar patterns in the changes of Pax3 and Pax7 expressions and the changes of Pax7+ve and Pax3+ve cell numbers were observed between the denervation- and disuse-induced atrophy models and this commonality was admitted among the muscle type. Therefore, we claim that the muscle regeneration orchestrated by satellite cells was governed by the muscle type in which satellite cells reside.
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Affiliation(s)
- Chuang-Yu Lin
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Chun-Yin Hou
- Department of Family Medicine, Taipei City Hospital, Zhongxiao Branch, Taipei, Taiwan
| | - Chung-Min Tsai
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Hsi Chang
- Department of Pediatrics, School of Medicine, College of Medicine, Taipei Medical University; Department of Pediatrics, Taipei Medical University Hospital, Taipei, Taiwan
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13
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Krekeler BN, Rowe LM, Connor NP. Dose in Exercise-Based Dysphagia Therapies: A Scoping Review. Dysphagia 2020; 36:1-32. [PMID: 32140905 DOI: 10.1007/s00455-020-10104-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 02/25/2020] [Indexed: 01/05/2023]
Abstract
BACKGROUND Optimal exercise doses for exercise-based approaches to dysphagia treatment are unclear. To address this gap in knowledge, we performed a scoping review to provide a record of doses reported in the literature. A larger goal of this work was to promote detailed consideration of dosing parameters in dysphagia exercise treatments in intervention planning and outcome reporting. METHODS We searched PubMed, Scopus[Embase], CINAHL, and Cochrane databases from inception to July 2019, with search terms relating to dysphagia and exercises to treat swallowing impairments. Of the eligible 1906 peer-reviewed articles, 72 met inclusionary criteria by reporting, at minimum, both the frequency and duration of their exercise-based treatments. RESULTS Study interventions included tongue exercise (n = 16), Shaker/head lift (n = 13), respiratory muscle strength training (n = 6), combination exercise programs (n = 20), mandibular movement exercises (n = 7), lip muscle training (n = 5), and other programs that did not fit into the categories described above (n = 5). Frequency recommendations varied greatly by exercise type. Duration recommendations ranged from 4 weeks to 1 year. In articles reporting repetitions (n = 66), the range was 1 to 120 reps/day. In articles reporting intensity (n = 59), descriptions included values for force, movement duration, or descriptive verbal cues, such as "as hard as possible." Outcome measures were highly varied across and within specific exercise types. CONCLUSIONS We recommend inclusion of at least the frequency, duration, repetition, and intensity components of exercise dose to improve reproducibility, interpretation, and comparison across studies. Further research is required to determine optimal dose ranges for the wide variety of exercise-based dysphagia interventions.
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Affiliation(s)
- Brittany N Krekeler
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Goodnight Hall, 1300 University Ave, Madison, WI, 53706, USA. .,Department of Surgery-Otolaryngology, Clinical Science Center, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI, 53792-7375, USA. .,Department of Communication Sciences and Disorders, Northwestern University, Swallowing Cross-Systems Collaborative, 2240 Campus Drive, Evanston, IL, 60208, USA.
| | - Linda M Rowe
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Goodnight Hall, 1300 University Ave, Madison, WI, 53706, USA.,Department of Surgery-Otolaryngology, Clinical Science Center, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI, 53792-7375, USA
| | - Nadine P Connor
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Goodnight Hall, 1300 University Ave, Madison, WI, 53706, USA.,Department of Surgery-Otolaryngology, Clinical Science Center, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI, 53792-7375, USA
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14
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Endurance-Type Exercise Increases Bulk and Individual Mitochondrial Protein Synthesis Rates in Rats. Int J Sport Nutr Exerc Metab 2020; 30:153–164. [DOI: 10.1123/ijsnem.2019-0281] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 11/22/2019] [Accepted: 11/27/2019] [Indexed: 11/18/2022]
Abstract
Physical activity increases muscle protein synthesis rates. However, the impact of exercise on the coordinated up- and/or downregulation of individual protein synthesis rates in skeletal muscle tissue remains unclear. The authors assessed the impact of exercise on mixed muscle, myofibrillar, and mitochondrial protein synthesis rates as well as individual protein synthesis rates in vivo in rats. Adult Lewis rats either remained sedentary (n = 3) or had access to a running wheel (n = 3) for the last 2 weeks of a 3-week experimental period. Deuterated water was injected and subsequently administered in drinking water over the experimental period. Blood and soleus muscle were collected and used to assess bulk mixed muscle, myofibrillar, and mitochondrial protein synthesis rates using gas chromatography–mass spectrometry and individual muscle protein synthesis rates using liquid chromatography–mass spectrometry (i.e., dynamic proteomic profiling). Wheel running resulted in greater myofibrillar (3.94 ± 0.26 vs. 3.03 ± 0.15%/day; p < .01) and mitochondrial (4.64 ± 0.24 vs. 3.97 ± 0.26%/day; p < .05), but not mixed muscle (2.64 ± 0.96 vs. 2.38 ± 0.62%/day; p = .71) protein synthesis rates, when compared with the sedentary condition. Exercise impacted the synthesis rates of 80 proteins, with the difference from the sedentary condition ranging between −64% and +420%. Significantly greater synthesis rates were detected for F1-ATP synthase, ATP synthase subunit alpha, hemoglobin, myosin light chain-6, and synaptopodin-2 (p < .05). The skeletal muscle protein adaptive response to endurance-type exercise involves upregulation of mitochondrial protein synthesis rates, but it is highly coordinated as reflected by the up- and downregulation of various individual proteins across different bulk subcellular protein fractions.
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15
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Rindom E, Kristensen AM, Overgaard K, Vissing K, Paoli FV. Activation of mTORC1 signalling in rat skeletal muscle is independent of the EC-coupling sequence but dependent on tension per se in a dose-response relationship. Acta Physiol (Oxf) 2019; 227:e13336. [PMID: 31231946 DOI: 10.1111/apha.13336] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 06/04/2019] [Accepted: 06/20/2019] [Indexed: 12/29/2022]
Abstract
AIM mTORC1 is regarded as an important key regulator of protein synthesis and hypertrophy following mechanical stimuli in skeletal muscle. However, as excitation and tension development is tightly coupled in most experimental models, very little and largely indirect evidence exist for such a mechanosensitive pathway. Here, we sought to examine whether activation of mTORC1 signalling is dependent on tension per se in rat skeletal muscle. METHODS To examine the mechanosensitivity of mTORC1, rat EDL muscles were exposed to either excitation-induced eccentric contractions (ECC), passive stretching (PAS) with identical peak tension (Tpeak ) and Tension-Time-Integral (TTI), or ECC with addition of inhibitors of the myosin ATPases (IMA ). To further explore the relationship between tension and mTORC1 signalling, rat EDL muscles were subjected to PAS of different magnitudes of Tpeak while standardizing TTI and vice versa. RESULTS PAS and ECC with equal Tpeak and TTI produced similar responses in mTORC1 signalling despite different modes of tension development. When active tension during ECC was nearly abolished by addition of IMA , mTORC1 signalling was reduced to a level comparable to non-stimulated controls. In addition, when muscles were exposed to PAS of varying levels of Tpeak with standardized TTI, activation of mTORC1 signalling displayed a positive relationship with peak tension. CONCLUSIONS The current study directly links tension per se to activation of mTORC1 signalling, which is independent of an active EC-coupling sequence. Moreover, activation of mTORC1 signalling displays a positive dose-response relationship with peak tension.
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Affiliation(s)
- Emil Rindom
- Department of Biomedicine Aarhus University Aarhus Denmark
| | - Anders M. Kristensen
- Section for Sport Science, Department of Public Health Aarhus University Aarhus Denmark
| | - 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
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16
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D'Hulst G, Palmer AS, Masschelein E, Bar-Nur O, De Bock K. Voluntary Resistance Running as a Model to Induce mTOR Activation in Mouse Skeletal Muscle. Front Physiol 2019; 10:1271. [PMID: 31636571 PMCID: PMC6787551 DOI: 10.3389/fphys.2019.01271] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/19/2019] [Indexed: 12/30/2022] Open
Abstract
Long-term voluntary resistance running has been shown to be a valid model to induce muscle growth in rodents. Moreover, the mammalian target of rapamycin complex 1 (mTORC1) is a key signaling complex regulating exercise/nutrient-induced alterations in muscle protein synthesis. How acute resistance running affects mTORC1 signaling in muscle and if resistance applied to the wheel can modulate mTORC1 activation has not yet been fully elucidated. Here, we show that both acute resistance running and acute free running activated mTORC1 signaling in the m. gastrocnemius, m. soleus, and m. plantaris, but not in m. tibialis anterior of mice when compared to sedentary controls. Furthermore, only the low threshold oxidative part in the m. gastrocnemius showed increased mTORC1 signaling upon running and acute heavy-load resistance running evoked higher downstream mTORC1 signaling in both m. soleus and m. plantaris than free running without resistance, pointing toward mechanical load as an important independent regulator of mTORC1. Collectively, in this study, we show that voluntary resistance running is an easy-to-use, time-efficient and low stress model to study acute alterations in mTORC1 signaling upon high-load muscular contractions in mice.
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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, Zurich, Switzerland
| | - Andrew S Palmer
- Laboratory of Regenerative and Movement Biology, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Evi Masschelein
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Ori Bar-Nur
- Laboratory of Regenerative and Movement Biology, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Katrien De Bock
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
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17
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Merle A, Jollet M, Britto FA, Goustard B, Bendridi N, Rieusset J, Ollendorff V, Favier FB. Endurance exercise decreases protein synthesis and ER-mitochondria contacts in mouse skeletal muscle. J Appl Physiol (1985) 2019; 127:1297-1306. [PMID: 31487224 DOI: 10.1152/japplphysiol.00196.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Exercise is important to maintain skeletal muscle mass through stimulation of protein synthesis, which is a major ATP-consuming process for cells. However, muscle cells have to face high energy demand during contraction. The present study aimed to investigate protein synthesis regulation during aerobic exercise in mouse hindlimb muscles. Male C57Bl/6J mice ran at 12 m/min for 45 min or at 12 m/min for the first 25 min followed by a progressive increase in velocity up to 20 m/min for the last 20 min. Animals were injected intraperitoneally with 40 nmol/g of body weight of puromycin and euthanized by cervical dislocation immediately after exercise cessation. Analysis of gastrocnemius, plantaris, quadriceps, soleus, and tibialis anterior muscles revealed a decrease in protein translation assessed by puromycin incorporation, without significant differences among muscles or running intensities. The reduction of protein synthesis was associated with a marked inhibition of mammalian target of rapamycin complex 1 (mTORC1)-dependent phosphorylation of eukaryotic translation initiation factor 4E-binding protein 1, a mechanism consistent with reduced translation initiation. A slight activation of AMP-activated protein kinase consecutive to the running session was measured but did not correlate with mTORC1 inhibition. More importantly, exercise resulted in a strong upregulation of regulated in development and DNA damage 1 (REDD1) protein and gene expressions, whereas transcriptional regulation of other recognized exercise-induced genes (IL-6, kruppel-like factor 15, and regulator of calcineurin 1) did not change. Consistently with the recently discovered role of REDD1 on mitochondria-associated membranes, we observed a decrease in mitochondria-endoplasmic reticulum interaction following exercise. Collectively, these data raise questions concerning the role of mitochondria-associated endoplasmic reticulum membrane disruption in the regulation of muscle proteostasis during exercise and, more generally, in cell adaptation to metabolic stress.NEW & NOTEWORTHY How muscles regulate protein synthesis to cope with the energy demand during contraction is poorly documented. Moreover, it is unknown whether protein translation is differentially affected among mouse hindlimb muscles under different physiological exercise modalities. We showed here that 45 min of running decreases puromycin incorporation similarly in 5 different mouse muscles. This decrease was associated with a strong increase in regulated in development and DNA damage 1 protein expression and a significant disruption of the mitochondria and sarcoplasmic reticulum interaction.
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Affiliation(s)
- Audrey Merle
- DMEM, University of Montpellier, INRA, Montpellier, France
| | - Maxence Jollet
- DMEM, University of Montpellier, INRA, Montpellier, France
| | | | | | - Nadia Bendridi
- INSERM CarMeN Laboratory, Lyon 1 University, INRA U1397, Oullins, France
| | - Jennifer Rieusset
- INSERM CarMeN Laboratory, Lyon 1 University, INRA U1397, Oullins, France
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18
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Boppart MD, Mahmassani ZS. Integrin signaling: linking mechanical stimulation to skeletal muscle hypertrophy. Am J Physiol Cell Physiol 2019; 317:C629-C641. [PMID: 31314586 DOI: 10.1152/ajpcell.00009.2019] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The α7β1-integrin is a transmembrane adhesion protein that connects laminin in the extracellular matrix (ECM) with actin in skeletal muscle fibers. The α7β1-integrin is highly expressed in skeletal muscle and is concentrated at costameres and myotendious junctions, providing the opportunity to transmit longitudinal and lateral forces across the membrane. Studies have demonstrated that α7-integrin subunit mRNA and protein are upregulated following eccentric contractions as a mechanism to reinforce load-bearing structures and resist injury with repeated bouts of exercise. It has been hypothesized for many years that the integrin can also promote protein turnover in a manner that can promote beneficial adaptations with resistance exercise training, including hypertrophy. This review provides basic information about integrin structure and activation and then explores its potential to serve as a critical mechanosensor and activator of muscle protein synthesis and growth. Overall, the hypothesis is proposed that the α7β1-integrin can contribute to mechanical-load induced skeletal muscle growth via an mammalian target of rapamycin complex 1-independent mechanism.
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Affiliation(s)
- Marni D Boppart
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Ziad S Mahmassani
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, Utah
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19
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Aguilar-Agon KW, Capel AJ, Martin NRW, Player DJ, Lewis MP. Mechanical loading stimulates hypertrophy in tissue-engineered skeletal muscle: Molecular and phenotypic responses. J Cell Physiol 2019; 234:23547-23558. [PMID: 31180593 PMCID: PMC6771594 DOI: 10.1002/jcp.28923] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/17/2019] [Accepted: 05/20/2019] [Indexed: 12/17/2022]
Abstract
Mechanical loading of skeletal muscle results in molecular and phenotypic adaptations typified by enhanced muscle size. Studies on humans are limited by the need for repeated sampling, and studies on animals have methodological and ethical limitations. In this investigation, three‐dimensional skeletal muscle was tissue‐engineered utilizing the murine cell line C2C12, which bears resemblance to native tissue and benefits from the advantages of conventional in vitro experiments. The work aimed to determine if mechanical loading induced an anabolic hypertrophic response, akin to that described in vivo after mechanical loading in the form of resistance exercise. Specifically, we temporally investigated candidate gene expression and Akt‐mechanistic target of rapamycin 1 signalling along with myotube growth and tissue function. Mechanical loading (construct length increase of 15%) significantly increased insulin‐like growth factor‐1 and MMP‐2 messenger RNA expression 21 hr after overload, and the levels of the atrophic gene MAFbx were significantly downregulated 45 hr after mechanical overload. In addition, p70S6 kinase and 4EBP‐1 phosphorylation were upregulated immediately after mechanical overload. Maximal contractile force was augmented 45 hr after load with a 265% increase in force, alongside significant hypertrophy of the myotubes within the engineered muscle. Overall, mechanical loading of tissue‐engineered skeletal muscle induced hypertrophy and improved force production.
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Affiliation(s)
- Kathryn W Aguilar-Agon
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Andrew J Capel
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Neil R W Martin
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Darren J Player
- Division of Surgery, University College London, London, United Kingdom
| | - Mark P Lewis
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
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20
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Pagnotti GM, Styner M, Uzer G, Patel VS, Wright LE, Ness KK, Guise TA, Rubin J, Rubin CT. Combating osteoporosis and obesity with exercise: leveraging cell mechanosensitivity. Nat Rev Endocrinol 2019; 15:339-355. [PMID: 30814687 PMCID: PMC6520125 DOI: 10.1038/s41574-019-0170-1] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Osteoporosis, a condition of skeletal decline that undermines quality of life, is treated with pharmacological interventions that are associated with poor adherence and adverse effects. Complicating efforts to improve clinical outcomes, the incidence of obesity is increasing, predisposing the population to a range of musculoskeletal complications and metabolic disorders. Pharmacological management of obesity has yet to deliver notable reductions in weight and debilitating complications are rarely avoided. By contrast, exercise shows promise as a non-invasive and non-pharmacological method of regulating both osteoporosis and obesity. The principal components of exercise - mechanical signals - promote bone and muscle anabolism while limiting formation and expansion of fat mass. Mechanical regulation of bone and marrow fat might be achieved by regulating functions of differentiated cells in the skeletal tissue while biasing lineage selection of their common progenitors - mesenchymal stem cells. An inverse relationship between adipocyte versus osteoblast fate selection from stem cells is implicated in clinical conditions such as childhood obesity and increased marrow adiposity in type 2 diabetes mellitus, as well as contributing to skeletal frailty. Understanding how exercise-induced mechanical signals can be used to improve bone quality while decreasing fat mass and metabolic dysfunction should lead to new strategies to treat chronic diseases such as osteoporosis and obesity.
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Affiliation(s)
- Gabriel M Pagnotti
- School of Medicine, Division of Endocrinology, Indiana University, Indianapolis, IN, USA
| | - Maya Styner
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC, USA
| | - Gunes Uzer
- College of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Vihitaben S Patel
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Laura E Wright
- School of Medicine, Division of Endocrinology, Indiana University, Indianapolis, IN, USA
| | - Kirsten K Ness
- Department of Epidemiology and Cancer Control, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Theresa A Guise
- School of Medicine, Division of Endocrinology, Indiana University, Indianapolis, IN, USA
| | - Janet Rubin
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC, USA
| | - Clinton T Rubin
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
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21
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Docquier A, Pavlin L, Raibon A, Bertrand‐Gaday C, Sar C, Leibovitch S, Candau R, Bernardi H. eIF3f depletion impedes mouse embryonic development, reduces adult skeletal muscle mass and amplifies muscle loss during disuse. J Physiol 2019; 597:3107-3131. [DOI: 10.1113/jp277841] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/24/2019] [Indexed: 12/19/2022] Open
Affiliation(s)
- Aurélie Docquier
- INRA, UMR866 Dynamique Musculaire et MétabolismeUniversité de Montpellier Montpellier France
| | - Laura Pavlin
- INRA, UMR866 Dynamique Musculaire et MétabolismeUniversité de Montpellier Montpellier France
| | - Audrey Raibon
- INRA, UMR866 Dynamique Musculaire et MétabolismeUniversité de Montpellier Montpellier France
| | | | - Chamroeun Sar
- Institut National de la Santé et de la Recherche Médicale, U‐583Institut des Neurosciences de MontpellierHôpital Saint Eloi Montpellier France
| | - Serge Leibovitch
- INRA, UMR866 Dynamique Musculaire et MétabolismeUniversité de Montpellier Montpellier France
| | - Robin Candau
- INRA, UMR866 Dynamique Musculaire et MétabolismeUniversité de Montpellier Montpellier France
| | - Henri Bernardi
- INRA, UMR866 Dynamique Musculaire et MétabolismeUniversité de Montpellier Montpellier France
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22
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Ato S, Tsushima D, Isono Y, Suginohara T, Maruyama Y, Nakazato K, Ogasawara R. The Effect of Changing the Contraction Mode During Resistance Training on mTORC1 Signaling and Muscle Protein Synthesis. Front Physiol 2019; 10:406. [PMID: 31057416 PMCID: PMC6482468 DOI: 10.3389/fphys.2019.00406] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 03/22/2019] [Indexed: 12/16/2022] Open
Abstract
Acute resistance exercise (RE) increases muscle protein synthesis (MPS) via activation of mechanistic target of rapamycin complex (mTORC), and chronic resistance exercise training (RT) results in skeletal muscle hypertrophy. Although MPS in response to RE is blunted over time during RT, no effective restorative strategy has been identified. Since eccentric muscle contraction (EC) has the potential to strongly stimulate mTORC1 activation and MPS, changing the muscle contraction mode to EC might maintain the MPS response to RE during chronic RT. Male rats were randomly divided into RE (1 bout of RE) and RT (13 bouts of RE) groups. Additionally, each group was subdivided into isometric contraction (IC) and EC subgroups. The RE groups performed acute, unilateral RE using IC or EC. The RT groups performed 12 bouts of unilateral RE using IC. For bout 13, the RT-IC subgroup performed a further IC bout, while the RT-EC subgroup changed to EC. All muscle contractions were induced by percutaneous electrical stimulation. Muscle samples were obtained at 6 h post exercise in all groups. After the 1st RE bout, the EC group showed significantly higher p70S6K Thr389 phosphorylation than the IC group. However, the phosphorylation of other mTORC1-associated proteins (4E-BP1 and ribosomal protein S6) and the MPS response did not differ between the contraction modes. After the 13th bout of RE, mTORC1 activation and the MPS response were significantly blunted as compared with the 1st bout of RE. Changing from IC to EC did not improve these responses. In conclusion, changing the contraction mode to EC does not reinvigorate the blunted mTORC1 activation and MPS in response to RE during chronic RT.
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Affiliation(s)
- Satoru Ato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Daisuke Tsushima
- Department of Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yurie Isono
- 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 Maruyama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Koichi Nakazato
- Department of Exercise Physiology, Nippon Sport Science University, Tokyo, Japan
| | - Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
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23
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An Anabolic Signaling Response of Rat Soleus Muscle to Eccentric Contractions Following Hindlimb Unloading: A Potential Role of Stretch-Activated Ion Channels. Int J Mol Sci 2019; 20:ijms20051165. [PMID: 30866432 PMCID: PMC6429234 DOI: 10.3390/ijms20051165] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 03/02/2019] [Accepted: 03/04/2019] [Indexed: 12/03/2022] Open
Abstract
Mechanisms that convert a mechanical signal into a biochemical response in an atrophied skeletal muscle remain poorly understood. The aims of the study were to evaluate a temporal response of anabolic signaling and protein synthesis (PS) to eccentric contractions (EC) in rat soleus during hindlimb unloading (HU); and to assess a possible role of stretch-activated ion channels (SAC) in the propagation of a mechanical signal to mTORC1 following HU. Following HU, an isolated soleus was subjected to EC. Upon completion of EC, muscles were collected for western blot analyses to determine the content/phosphorylation of the key anabolic markers. We found that a degree of EC-induced p70S6K phosphorylation and the rate of PS in the soleus of 3- and 7-day unloaded rats was significantly less than that in control. A decrease in EC-induced phosphorylation of p70S6K, RPS6 and PS in the 7-day unloaded soleus treated with SAC inhibitor did not differ from that of the 7-day unloaded soleus without SAC blockade. The results of the study suggest that (i) HU results in a blunted anabolic response to a bout of EC, (ii) attenuation of mTORC1-signaling and PS in response to EC in unloaded soleus may be associated with inactivation of SAC.
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You JS, McNally RM, Jacobs BL, Privett RE, Gundermann DM, Lin KH, Steinert ND, Goodman CA, Hornberger TA. The role of raptor in the mechanical load-induced regulation of mTOR signaling, protein synthesis, and skeletal muscle hypertrophy. FASEB J 2019; 33:4021-4034. [PMID: 30509128 PMCID: PMC6404572 DOI: 10.1096/fj.201801653rr] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 11/05/2018] [Indexed: 12/21/2022]
Abstract
It is well known that an increase in mechanical loading can induce skeletal muscle hypertrophy, and a long standing model in the field indicates that mechanical loads induce hypertrophy via a mechanism that requires signaling through the mechanistic target of rapamycin complex 1 (mTORC1). Specifically, it has been widely proposed that mechanical loads activate signaling through mTORC1 and that this, in turn, promotes an increase in the rate of protein synthesis and the subsequent hypertrophic response. However, this model is based on a number of important assumptions that have not been rigorously tested. In this study, we created skeletal muscle specific and inducible raptor knockout mice to eliminate signaling by mTORC1, and with these mice we were able to directly demonstrate that mechanical stimuli can activate signaling by mTORC1, and that mTORC1 is necessary for mechanical load-induced hypertrophy. Surprisingly, however, we also obtained multiple lines of evidence that indicate that mTORC1 is not required for a mechanical load-induced increase in the rate of protein synthesis. This observation highlights an important shortcoming in our understanding of how mechanical loads induce hypertrophy and illustrates that additional mTORC1-independent mechanisms play a critical role in this process.-You, J.-S., McNally, R. M., Jacobs, B. L., Privett, R. E., Gundermann, D. M., Lin, K.-H., Steinert, N. D., Goodman, C. A., Hornberger, T. A. The role of raptor in the mechanical load-induced regulation of mTOR signaling, protein synthesis, and skeletal muscle hypertrophy.
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Affiliation(s)
- Jae-Sung You
- Department of Comparative Biosciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
- School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Rachel M. McNally
- Department of Comparative Biosciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
- School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Brittany L. Jacobs
- Department of Comparative Biosciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
- School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Rachel E. Privett
- Department of Comparative Biosciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
- School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - David M. Gundermann
- Department of Comparative Biosciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
- School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Kuan-Hung Lin
- Department of Comparative Biosciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
- School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Nate D. Steinert
- Department of Comparative Biosciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
- School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Craig A. Goodman
- Department of Comparative Biosciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
- School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, USA
- Institute of Health and Sport, Victoria University, Melbourne, Victoria, Australia
- Australian Institute for Musculoskeletal Science, Victoria University, St. Albans, Victoria, Australia
| | - Troy A. Hornberger
- Department of Comparative Biosciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
- School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, USA
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25
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Goodman CA. Role of mTORC1 in mechanically induced increases in translation and skeletal muscle mass. J Appl Physiol (1985) 2019; 127:581-590. [PMID: 30676865 DOI: 10.1152/japplphysiol.01011.2018] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Skeletal muscle mass is, in part, regulated by the rate of mRNA translation (i.e., protein synthesis). The conserved serine/threonine kinase, mTOR (the mammalian/mechanistic target of rapamycin), found in the multiprotein complex, mTOR complex 1 (mTORC1), is a major positive regulator of protein synthesis. The purpose of this review is to describe some of the critical steps in translation initiation, mTORC1 and its potential direct and indirect roles in regulating translation, and evidence that mTORC1 regulates protein synthesis and muscle mass, with a particular focus on basal conditions and the response to mechanical stimuli. Current evidence suggests that for acute contraction models of mechanical stimuli, there is an emerging pattern suggesting that there is an early increase in protein synthesis governed by a rapamycin-sensitive mTORC1-dependent mechanism, while at later poststimulation time points, the mechanism may change to a rapamycin-insensitive mTORC1-dependent or even an mTORC1-independent mechanism. Furthermore, evidence suggests that mTORC1 appears to be absolutely necessary for muscle fiber hypertrophy induced by chronic mechanical loading but may only play a partial role in the hypertrophy induced by more intermittent types of acute resistance exercise, with the possibility of mTORC1-independent mechanisms also playing a role. Despite the progress that has been made, many questions about the activation of mTORC1, and its downstream targets, remain to be answered. Further research will hopefully provide novel insights into the regulation of skeletal muscle mTORC1 that may eventually be translated into novel exercise programing and/or targeted pharmacological therapies aimed at preventing muscle wasting and/or increasing muscle mass.
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Affiliation(s)
- Craig A Goodman
- Institute of Health and Sport; Victoria University, Melbourne, Australia.,Australian Institute for Musculoskeletal Science (AIMSS), Victoria University, St. Albans, Victoria, Australia
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26
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Ohno Y, Egawa T, Yokoyama S, Fujiya H, Sugiura T, Ohira Y, Yoshioka T, Goto K. MENS-associated increase of muscular protein content via modulation of caveolin-3 and TRIM72. Physiol Res 2019; 68:265-273. [PMID: 30628834 DOI: 10.33549/physiolres.933992] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Microcurrent electrical neuromuscular stimulation (MENS) is known as an extracellular stimulus for the regeneration of injured skeletal muscle in sports medicine. However, the effects of MENS-associated increase in muscle protein content are not fully clarified. The purpose of this study was to investigate the effects of MENS on the muscular protein content, intracellular signals, and the expression level of caveolin-3 (Cav-3), tripartite motif-containing 72 (TRIM72) and MM isoenzyme of creatine kinase (CK-MM) in skeletal muscle using cell culture system. C2C12 myotubes on the 7th day of differentiation phase were treated with MENS (intensity: 10-20 microA, frequency: 0.3 Hz, pulse width: 250 ms, stimulation time: 15-120 min). MENS-associated increase in the protein content of myotubes was observed, compared to the untreated control level. MENS upregulated the expression of Cav-3, TRIM72, and CK-MM in myotubes. A transient increase in phosphorylation level of Akt was also observed. However, MENS had no effect on the phosphorylation level of p42/44 extracellular signal-regulated kinase-1/2 and 5'AMP-activated protein kinase. MENS may increase muscle protein content accompanied with a transient activation of Akt and the upregulation of Cav-3 and TRIM72.
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Affiliation(s)
- Y Ohno
- Department of Physiology, Graduate School of Health Sciences, Toyohashi SOZO University, Aichi, Japan.
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27
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Mirzoev TM, Shenkman BS. Regulation of Protein Synthesis in Inactivated Skeletal Muscle: Signal Inputs, Protein Kinase Cascades, and Ribosome Biogenesis. BIOCHEMISTRY (MOSCOW) 2018; 83:1299-1317. [PMID: 30482143 DOI: 10.1134/s0006297918110020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Disuse atrophy of skeletal muscles is characterized by a significant decrease in the mass and size of muscle fibers. Disuse atrophy develops as a result of prolonged reduction in the muscle functional activity caused by bed rest, limb immobilization, and real or simulated microgravity. Disuse atrophy is associated with the downregulation of protein biosynthesis and simultaneous activation of protein degradation. This review is focused on the key molecular mechanisms regulating the rate of protein synthesis in mammalian skeletal muscles during functional unloading.
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Affiliation(s)
- T M Mirzoev
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, 123007, Russia.
| | - B S Shenkman
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, 123007, Russia
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28
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The Role of Eif6 in Skeletal Muscle Homeostasis Revealed by Endurance Training Co-expression Networks. Cell Rep 2018; 21:1507-1520. [PMID: 29117557 PMCID: PMC5695912 DOI: 10.1016/j.celrep.2017.10.040] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 08/16/2017] [Accepted: 10/11/2017] [Indexed: 12/20/2022] Open
Abstract
Regular endurance training improves muscle oxidative capacity and reduces the risk of age-related disorders. Understanding the molecular networks underlying this phenomenon is crucial. Here, by exploiting the power of computational modeling, we show that endurance training induces profound changes in gene regulatory networks linking signaling and selective control of translation to energy metabolism and tissue remodeling. We discovered that knockdown of the mTOR-independent factor Eif6, which we predicted to be a key regulator of this process, affects mitochondrial respiration efficiency, ROS production, and exercise performance. Our work demonstrates the validity of a data-driven approach to understanding muscle homeostasis. Endurance exercise profoundly affects the structure of gene networks Eif6 is a hub in gene networks responsible for muscle metabolism and protein synthesis Mitochondrial metabolic capacity altered in muscle from Eif6+/− mice Eif6 haploinsufficiency increased ROS generation and reduced exercise performance
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29
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Cant JP, Kim JJ, Cieslar SR, Doelman J. Symposium review: Amino acid uptake by the mammary glands: Where does the control lie? J Dairy Sci 2018; 101:5655-5666. [DOI: 10.3168/jds.2017-13844] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/28/2018] [Indexed: 12/15/2022]
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30
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Martins CEC, Lima VBDS, Schoenfeld BJ, Tirapegui J. Effects of leucine supplementation and resistance training on myopathy of diabetic rats. Physiol Rep 2018; 5:e13273. [PMID: 28536139 PMCID: PMC5449559 DOI: 10.14814/phy2.13273] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 11/24/2022] Open
Abstract
Leucine supplementation and resistance training positively influence the protein translation process and the cell signaling mTOR (mammalian target of rapamycin) pathway that regulates muscle protein balance and muscle remodeling, and thus may be therapeutic to diabetic myopathy. However, the effect of a combined intervention has not been well studied. Forty male Wistar rats were divided into five groups, control (C), diabetic control (D), diabetic + trained (DT), diabetic + L-leucine (DL), diabetic + L-leucine + trained (DLT). The supplementation of 5% leucine in chow, and resistance training were conducted for 8 weeks postweaning of rats. The extensor digitorum longus was used to assess signaling proteins involved in muscle protein synthesis, and the gastrocnemius and soleus were used for determination of muscle weight. Blood samples were collected for biochemical assays. Strength and ambulation tests were employed to evaluate motor performance. Results showed that both leucine supplementation and resistance training elevated the activity of mTOR-p70S6K in diabetic rats (P < 0.05). Moreover, though leucine supplementation in combination with resistance training demonstrated synergistic effects on p70S6K (P < 0.05), both treatments were capable of recovering motor performance (P < 0.05). In conclusion, 5% leucine supplementation combined with resistance training has the potential to attenuate muscle loss and motor performance decrements in diabetic rats, at least in part through increased protein synthesis.
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Affiliation(s)
- Carlos Eduardo C Martins
- Department of Food Science and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Vanessa B de S Lima
- Department of Food Science and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | | | - Julio Tirapegui
- Department of Food Science and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
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31
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Ato S, Makanae Y, Kido K, Fujita S. Contraction mode itself does not determine the level of mTORC1 activity in rat skeletal muscle. Physiol Rep 2017; 4:4/19/e12976. [PMID: 27688433 PMCID: PMC5064134 DOI: 10.14814/phy2.12976] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 08/19/2016] [Indexed: 11/24/2022] Open
Abstract
Resistance training with eccentric contraction has been shown to augment muscle hypertrophy more than other contraction modes do (i.e., concentric and isometric contraction). However, the molecular mechanisms involved remain unclear. The purpose of this study was to investigate the effect of muscle contraction mode on mammalian target of rapamycin complex 1 (mTORC1) signaling using a standardized force‐time integral (load (weight) × contraction time). Male Sprague–Dawley rats were randomly assigned to three groups: eccentric contraction, concentric contraction, and isometric contraction. The right gastrocnemius muscle was exercised via percutaneous electrical stimulation‐induced maximal contraction. In experiment 1, different modes of muscle contraction were exerted using the same number of reps in all groups, while in experiment 2, muscle contractions were exerted using a standardized force‐time integral. Muscle samples were obtained immediately and 3 h after exercise. Phosphorylation of molecules associated with mTORC1 activity was assessed using western blot analysis. In experiment 1, the force‐time integral was significantly different among contraction modes with a higher force‐time integral for eccentric contraction compared to that for other contraction modes (P < 0.05). In addition, the force‐time integral was higher for concentric contraction compared to that for isometric contraction (P < 0.05). Similarly, p70S6K phosphorylation level was higher for eccentric contraction than for other modes of contraction (P < 0.05), and concentric contraction was higher than isometric contraction (P < 0.05) 3 h after exercise. In experiment 2, under the same force‐time integral, p70S6K (Thr389) and 4E‐BP1 phosphorylation levels were similar among contraction modes 3 h after exercise. Our results suggest that mTORC1 activity is not determined by differences in muscle contraction mode itself. Instead, mTORC1 activity is determined by differences in the force‐time integral during muscle contraction.
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Affiliation(s)
- Satoru Ato
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan
| | - Yuhei Makanae
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan
| | - Kohei Kido
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan
| | - Satoshi Fujita
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan
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32
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Goodman CA, Coenen AM, Frey JW, You JS, Barker RG, Frankish BP, Murphy RM, Hornberger TA. Insights into the role and regulation of TCTP in skeletal muscle. Oncotarget 2017; 8:18754-18772. [PMID: 27813490 PMCID: PMC5386645 DOI: 10.18632/oncotarget.13009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 09/28/2016] [Indexed: 01/07/2023] Open
Abstract
The translationally controlled tumor protein (TCTP) is upregulated in a range of cancer cell types, in part, by the activation of the mechanistic target of rapamycin (mTOR). Recently, TCTP has also been proposed to act as an indirect activator of mTOR. While it is known that mTOR plays a major role in the regulation of skeletal muscle mass, very little is known about the role and regulation of TCTP in this post-mitotic tissue. This study shows that muscle TCTP and mTOR signaling are upregulated in a range of mouse models (mdx mouse, mechanical load-induced hypertrophy, and denervation- and immobilization-induced atrophy). Furthermore, the increase in TCTP observed in the hypertrophic and atrophic conditions occurred, in part, via a rapamycin-sensitive mTOR-dependent mechanism. However, the overexpression of TCTP was not sufficient to activate mTOR signaling (or increase protein synthesis) and is thus unlikely to take part in a recently proposed positive feedback loop with mTOR. Nonetheless, TCTP overexpression was sufficient to induce muscle fiber hypertrophy. Finally, TCTP overexpression inhibited the promoter activity of the muscle-specific ubiquitin proteasome E3-ligase, MuRF1, suggesting that TCTP may play a role in inhibiting protein degradation. These findings provide novel data on the role and regulation of TCTP in skeletal muscle in vivo.
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Affiliation(s)
- Craig A Goodman
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA.,Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, Melbourne, Victoria, 8001, Australia.,Institute for Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, 8001, Australia
| | - Allison M Coenen
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
| | - John W Frey
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
| | - Jae-Sung You
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
| | - Robert G Barker
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Barnaby P Frankish
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Robyn M Murphy
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Troy A Hornberger
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
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33
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Martin NRW, Turner MC, Farrington R, Player DJ, Lewis MP. Leucine elicits myotube hypertrophy and enhances maximal contractile force in tissue engineered skeletal muscle in vitro. J Cell Physiol 2017; 232:2788-2797. [PMID: 28409828 PMCID: PMC5518187 DOI: 10.1002/jcp.25960] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 04/13/2017] [Indexed: 01/07/2023]
Abstract
The amino acid leucine is thought to be important for skeletal muscle growth by virtue of its ability to acutely activate mTORC1 and enhance muscle protein synthesis, yet little data exist regarding its impact on skeletal muscle size and its ability to produce force. We utilized a tissue engineering approach in order to test whether supplementing culture medium with leucine could enhance mTORC1 signaling, myotube growth, and muscle function. Phosphorylation of the mTORC1 target proteins 4EBP-1 and rpS6 and myotube hypertrophy appeared to occur in a dose dependent manner, with 5 and 20 mM of leucine inducing similar effects, which were greater than those seen with 1 mM. Maximal contractile force was also elevated with leucine supplementation; however, although this did not appear to be enhanced with increasing leucine doses, this effect was completely ablated by co-incubation with the mTOR inhibitor rapamycin, showing that the augmented force production in the presence of leucine was mTOR sensitive. Finally, by using electrical stimulation to induce chronic (24 hr) contraction of engineered skeletal muscle constructs, we were able to show that the effects of leucine and muscle contraction are additive, since the two stimuli had cumulative effects on maximal contractile force production. These results extend our current knowledge of the efficacy of leucine as an anabolic nutritional aid showing for the first time that leucine supplementation may augment skeletal muscle functional capacity, and furthermore validates the use of engineered skeletal muscle for highly-controlled investigations into nutritional regulation of muscle physiology.
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Affiliation(s)
- Neil R W Martin
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Mark C Turner
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Robert Farrington
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Darren J Player
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Mark P Lewis
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
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34
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Intramuscular Anabolic Signaling and Endocrine Response Following Resistance Exercise: Implications for Muscle Hypertrophy. Sports Med 2017; 46:671-85. [PMID: 26666743 DOI: 10.1007/s40279-015-0450-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Maintaining skeletal muscle mass and function is critical for disease prevention, mobility and quality of life, and whole-body metabolism. Resistance exercise is known to be a major regulator for promoting muscle protein synthesis and muscle mass accretion. Manipulation of exercise intensity, volume, and rest elicit specific muscular adaptations that can maximize the magnitude of muscle growth. The stimulus of muscle contraction that occurs during differing intensities of resistance exercise results in varying biochemical responses regulating the rate of protein synthesis, known as mechanotransduction. At the cellular level, skeletal muscle adaptation appears to be the result of the cumulative effects of transient changes in gene expression following acute bouts of exercise. Thus, maximizing the resistance exercise-induced anabolic response produces the greatest potential for hypertrophic adaptation with training. The mechanisms involved in converting mechanical signals into the molecular events that control muscle growth are not completely understood; however, skeletal muscle protein synthesis appears to be regulated by the multi-protein phosphorylation cascade, mTORC1 (mammalian/mechanistic target of rapamycin complex 1). The purpose of this review is to examine the physiological response to resistance exercise, with particular emphasis on the endocrine response and intramuscular anabolic signaling through mTORC1. It appears that resistance exercise protocols that maximize muscle fiber recruitment, time-under-tension, and metabolic stress will contribute to maximizing intramuscular anabolic signaling; however, the resistance exercise parameters for maximizing the anabolic response remain unclear.
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35
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Mobley CB, Holland AM, Kephart WC, Mumford PW, Lowery RP, Kavazis AN, Wilson JM, Roberts MD. Progressive resistance-loaded voluntary wheel running increases hypertrophy and differentially affects muscle protein synthesis, ribosome biogenesis, and proteolytic markers in rat muscle. J Anim Physiol Anim Nutr (Berl) 2017; 102:317-329. [DOI: 10.1111/jpn.12691] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 01/12/2017] [Indexed: 01/04/2023]
Affiliation(s)
| | | | | | | | - R. P. Lowery
- Applied Science and Performance Institute; Tampa FL USA
| | - A. N. Kavazis
- Auburn University; Auburn AL USA
- Edward Via College of Osteopathic Medicine - Auburn Campus; Auburn AL USA
| | - J. M. Wilson
- Applied Science and Performance Institute; Tampa FL USA
| | - M. D. Roberts
- Auburn University; Auburn AL USA
- Edward Via College of Osteopathic Medicine - Auburn Campus; Auburn AL USA
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36
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Rindom E, Vissing K. Mechanosensitive Molecular Networks Involved in Transducing Resistance Exercise-Signals into Muscle Protein Accretion. Front Physiol 2016; 7:547. [PMID: 27909410 PMCID: PMC5112233 DOI: 10.3389/fphys.2016.00547] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/31/2016] [Indexed: 02/05/2023] Open
Abstract
Loss of skeletal muscle myofibrillar protein with disease and/or inactivity can severely deteriorate muscle strength and function. Strategies to counteract wasting of muscle myofibrillar protein are therefore desirable and invite for considerations on the potential superiority of specific modes of resistance exercise and/or the adequacy of low load resistance exercise regimens as well as underlying mechanisms. In this regard, delineation of the potentially mechanosensitive molecular mechanisms underlying muscle protein synthesis (MPS), may contribute to an understanding on how differentiated resistance exercise can transduce a mechanical signal into stimulation of muscle accretion. Recent findings suggest specific upstream exercise-induced mechano-sensitive myocellular signaling pathways to converge on mammalian target of rapamycin complex 1 (mTORC1), to influence MPS. This may e.g. implicate mechanical activation of signaling through a diacylglycerol kinase (DGKζ)-phosphatidic acid (PA) axis or implicate integrin deformation to signal through a Focal adhesion kinase (FAK)-Tuberous Sclerosis Complex 2 (TSC2)-Ras homolog enriched in brain (Rheb) axis. Moreover, since initiation of translation is reliant on mRNA, it is also relevant to consider potentially mechanosensitive signaling pathways involved in muscle myofibrillar gene transcription and whether some of these pathways converge with those affecting mTORC1 activation for MPS. In this regard, recent findings suggest how mechanical stress may implicate integrin deformation and/or actin dynamics to signal through a Ras homolog gene family member A protein (RhoA)-striated muscle activator of Rho signaling (STARS) axis or implicate deformation of Notch to affect Bone Morphogenetic Protein (BMP) signaling through a small mother of decapentaplegic (Smad) axis.
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Affiliation(s)
- Emil Rindom
- Section of Sport Science, Department of Public Health, Aarhus UniversityAarhus, Denmark; Department of Biomedicine, Aarhus UniversityAarhus, Denmark
| | - Kristian Vissing
- Section of Sport Science, Department of Public Health, Aarhus University Aarhus, Denmark
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37
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Brocca L, Longa E, Cannavino J, Seynnes O, de Vito G, McPhee J, Narici M, Pellegrino MA, Bottinelli R. Human skeletal muscle fibre contractile properties and proteomic profile: adaptations to 3 weeks of unilateral lower limb suspension and active recovery. J Physiol 2016; 593:5361-85. [PMID: 26369674 DOI: 10.1113/jp271188] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 09/04/2015] [Indexed: 01/08/2023] Open
Abstract
KEY POINTS It is generally assumed that muscle fibres go through atrophy following disuse with a loss of specific force and an increase in unloaded shortening velocity. However, the underlying mechanisms remain to be clarified. Most studies have focused on events taking place during the development of disuse, whereas the subsequent recovery phase, which is equally important, has received little attention. Our findings support the hypotheses that the specific force of muscle fibres decreased following unilateral lower limb suspension (ULLS) and returned to normal after 3 weeks of active recovery as a result of a loss and recovery of myosin and actin content. Furthermore, muscle fibres went through extensive qualitative changes in muscle protein pattern following ULLS, and these were reversed by active recovery. Resistance training was very effective in restoring both muscle mass and qualitative muscle changes, indicating that long-term ULLS did not prevent the positive effect of exercise on human muscle. ABSTRACT Following disuse, muscle fibre function goes through adaptations such as a loss of specific force (PO /CSA) and an increase in unloaded shortening velocity, which could be a result of both quantitative changes (i.e. atrophy) and qualitative changes in protein pattern. The underlying mechanisms remain to be clarified. In addition, little is known about the recovery of muscle mass and strength following disuse. In the present study, we report an extensive dataset describing, in detail,the functional and protein content adaptations of skeletal muscle in response to both disuse and re-training. Eight young healthy subjects were subjected to 3 weeks of unilateral lower limb suspension (ULLS), a widely used human model of disuse skeletal muscle atrophy. Needle biopsies samples were taken from the vastus lateralis muscle Pre-ULLS, Post-ULLS and after 3 weeks of recovery during which heavy resistance training was performed. After disuse, cross-sectional area (CSA), PO /CSA and myosin concentration (MC) decreased in both type 1 and 2A skinned muscle fibres. After recovery, CSA and MC returned to levels comparable to those observed before disuse, whereas Po/CSA and unloaded shortening velocity reached a higher level. Myosin heavy chain isoform composition of muscle samples did not differ among the experimental groups. To study the mechanisms underlying such adaptations, a two-dimensional proteomic analysis was performed. ULLS induced a reduction of myofibrillar, metabolic (glycolytic and oxidative) and anti-oxidant defence system protein content. Resistance training was very effective in counteracting ULLS-induced alterations, indicating that long-term ULLS did not prevent the positive effect of exercise on human muscle.
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Affiliation(s)
- Lorenza Brocca
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Interuniversity Institute of Myology, University of Pavia, Pavia, Italy
| | - Emanuela Longa
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Interdipartimental Centre for Biology and Sport Medicine, University of Pavia, Pavia, Italy
| | | | - Olivier Seynnes
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, UK.,Norwegian School of Sport Sciences, Oslo, Norway
| | - Giuseppe de Vito
- UCD Institute for Sport and Health, University College Dublin, Dublin, Ireland
| | - Jamie McPhee
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, UK
| | - Marco Narici
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, UK.,School of Graduate Entry to Medicine and Health, Division of Clinical Physiology, University of Nottingham, Derby, UK
| | - Maria Antonietta Pellegrino
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Interdipartimental Centre for Biology and Sport Medicine, University of Pavia, Pavia, Italy.,Interuniversity Institute of Myology, University of Pavia, Pavia, Italy
| | - Roberto Bottinelli
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Fondazione Salvatore Maugeri (IRCCS), Scientific Institute of Pavia, Pavia, Italy
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38
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von Walden F, Liu C, Aurigemma N, Nader GA. mTOR signaling regulates myotube hypertrophy by modulating protein synthesis, rDNA transcription, and chromatin remodeling. Am J Physiol Cell Physiol 2016; 311:C663-C672. [DOI: 10.1152/ajpcell.00144.2016] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/30/2016] [Indexed: 01/15/2023]
Abstract
Ribosome production is an early event during skeletal muscle hypertrophy and precedes muscle protein accretion. Signaling via mTOR is crucial for ribosome production and hypertrophy; however, the mechanisms by which it regulates these processes remain to be identified. Herein, we investigated the activation of mTOR signaling in hypertrophying myotubes and determined that mTOR coordinates various aspects of gene expression important for ribosome production. First, inhibition of translation with cycloheximide had a more potent effect on protein synthesis than rapamycin indicating that mTOR function during hypertrophy is not on general, but rather on specific protein synthesis. Second, blocking Pol II transcription had a similar effect as Rapamycin and, unexpectedly, revealed the necessity of Pol II transcription for Pol I transcription, suggesting that mTOR may regulate ribosome production also by controlling Class II genes at the transcriptional level. Third, Pol I activity is essential for rDNA transcription and, surprisingly, for protein synthesis as selective Pol I inhibition blunted rDNA transcription, protein synthesis, and the hypertrophic response of myotubes. Finally, mTOR has nuclear localization in muscle, which is not sensitive to rapamycin. Inhibition of mTOR signaling by rapamycin disrupted mTOR-rDNA promoter interaction and resulted in altered histone marks indicative of repressed transcription and formation of higher-order chromatin structure. Thus mTOR signaling appears to regulate muscle hypertrophy by affecting protein synthesis, Class I and II gene expression, and chromatin remodeling.
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Affiliation(s)
- Ferdinand von Walden
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Chang Liu
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Nicole Aurigemma
- Noll Laboratory, Department of Kinesiology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania; and
| | - Gustavo A. Nader
- Noll Laboratory, Department of Kinesiology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania; and
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
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39
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Mukai R, Horikawa H, Lin PY, Tsukumo N, Nikawa T, Kawamura T, Nemoto H, Terao J. 8-Prenylnaringenin promotes recovery from immobilization-induced disuse muscle atrophy through activation of the Akt phosphorylation pathway in mice. Am J Physiol Regul Integr Comp Physiol 2016; 311:R1022-R1031. [PMID: 27629889 DOI: 10.1152/ajpregu.00521.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 08/09/2016] [Accepted: 08/30/2016] [Indexed: 01/06/2023]
Abstract
8-Prenylnaringenin (8-PN) is a prenylflavonoid that originates from hop extracts and is thought to help prevent disuse muscle atrophy. We hypothesized that 8-PN affects muscle plasticity by promoting muscle recovery under disuse muscle atrophy. To test the promoting effect of 8-PN on muscle recovery, we administered an 8-PN mixed diet to mice that had been immobilized with a cast to one leg for 14 days. Intake of the 8-PN mixed diet accelerated recovery from muscle atrophy, and prevented reductions in Akt phosphorylation. Studies on cell cultures of mouse myotubes in vitro demonstrated that 8-PN activated the PI3K/Akt/P70S6K1 pathway at physiological concentrations. A cell-culture study using an inhibitor of estrogen receptors and an in vivo experiment with ovariectomized mice suggested that the estrogenic activity of 8-PN contributed to recovery from disuse muscle atrophy through activation of an Akt phosphorylation pathway. These data strongly suggest that 8-PN is a naturally occurring compound that could be used as a nutritional supplement to aid recovery from disuse muscle atrophy.
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Affiliation(s)
- Rie Mukai
- Department of Food Science, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan;
| | - Hitomi Horikawa
- Department of Food Science, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Pei-Yi Lin
- Department of Food Science, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Nao Tsukumo
- Department of Food Science, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Takeshi Nikawa
- Department of Nutritional Physiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; and
| | - Tomoyuki Kawamura
- Department of Pharmaceutical Chemistry, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Hisao Nemoto
- Department of Pharmaceutical Chemistry, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Junji Terao
- Department of Food Science, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
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40
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Ogasawara R, Fujita S, Hornberger TA, Kitaoka Y, Makanae Y, Nakazato K, Naokata I. The role of mTOR signalling in the regulation of skeletal muscle mass in a rodent model of resistance exercise. Sci Rep 2016; 6:31142. [PMID: 27502839 PMCID: PMC4977552 DOI: 10.1038/srep31142] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/14/2016] [Indexed: 12/13/2022] Open
Abstract
Resistance exercise (RE) activates signalling by the mammalian target of rapamycin (mTOR), and it has been suggested that rapamycin-sensitive mTOR signalling controls RE-induced changes in protein synthesis, ribosome biogenesis, autophagy, and the expression of peroxisome proliferator gamma coactivator 1 alpha (PGC-1α). However, direct evidence to support the aforementioned relationships is lacking. Therefore, in this study, we investigated the role of rapamycin-sensitive mTOR in the RE-induced activation of muscle protein synthesis, ribosome biogenesis, PGC-1α expression and hypertrophy. The results indicated that the inhibition of rapamycin-sensitive mTOR could prevent the induction of ribosome biogenesis by RE, but it only partially inhibited the activation of muscle protein synthesis. Likewise, the inhibition of rapamycin-sensitive mTOR only partially blocked the hypertrophic effects of chronic RE. Furthermore, both acute and chronic RE promoted an increase in PGC-1α expression and these alterations were not affected by the inhibition of rapamycin-sensitive mTOR. Combined, the results from this study not only establish that rapamycin-sensitive mTOR plays an important role in the RE-induced activation of protein synthesis and the induction of hypertrophy, but they also demonstrate that additional (rapamycin-sensitive mTOR-independent) mechanisms contribute to these fundamentally important events.
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Affiliation(s)
- Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
- Department of Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Satoshi Fujita
- Department of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan
| | - Troy A. Hornberger
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Yu Kitaoka
- Department of Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuhei Makanae
- Department of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan
| | - Koichi Nakazato
- Department of exercise physiology, Nippon Sport Science University, Tokyo, Japan
| | - Ishii Naokata
- Department of Life Sciences, The University of Tokyo, Tokyo, Japan
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41
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Corpeno Kalamgi R, Salah H, Gastaldello S, Martinez-Redondo V, Ruas JL, Fury W, Bai Y, Gromada J, Sartori R, Guttridge DC, Sandri M, Larsson L. Mechano-signalling pathways in an experimental intensive critical illness myopathy model. J Physiol 2016; 594:4371-88. [PMID: 26990577 DOI: 10.1113/jp271973] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/11/2016] [Indexed: 01/07/2023] Open
Abstract
KEY POINTS Using an experimental rat intensive care unit (ICU) model, not limited by early mortality, we have previously shown that passive mechanical loading attenuates the loss of muscle mass and force-generation capacity associated with the ICU intervention. Mitochondrial dynamics have recently been shown to play a more important role in muscle atrophy than previously recognized. In this study we demonstrate that mitochondrial dynamics, as well as mitophagy, is affected by mechanosensing at the transcriptional level, and muscle changes induced by unloading are counteracted by passive mechanical loading. The recently discovered ubiquitin ligases Fbxo31 and SMART are induced by mechanical silencing, an induction that similarly is prevented by passive mechanical loading. ABSTRACT The complete loss of mechanical stimuli of skeletal muscles, i.e. loss of external strain related to weight bearing and internal strain related to activation of contractile proteins, in mechanically ventilated, deeply sedated and/or pharmacologically paralysed intensive care unit (ICU) patients is an important factor triggering the critical illness myopathy (CIM). Using a unique experimental ICU rat model, mimicking basic ICU conditions, we have recently shown that mechanical silencing is a dominant factor triggering the preferential loss of myosin, muscle atrophy and decreased specific force in fast- and slow-twitch muscles and muscle fibres. The aim of this study is to gain improved understanding of the gene signature and molecular pathways regulating the process of mechanical activation of skeletal muscle that are affected by the ICU condition. We have focused on pathways controlling myofibrillar protein synthesis and degradation, mitochondrial homeostasis and apoptosis. We demonstrate that genes regulating mitochondrial dynamics, as well as mitophagy are induced by mechanical silencing and that these effects are counteracted by passive mechanical loading. In addition, the recently identified ubiquitin ligases Fbxo31 and SMART are induced by mechanical silencing, an induction that is reversed by passive mechanical loading. Thus, mechano-cell signalling events are identified which may play an important role for the improved clinical outcomes reported in response to the early mobilization and physical therapy in immobilized ICU patients.
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Affiliation(s)
- Rebeca Corpeno Kalamgi
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Heba Salah
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Stefano Gastaldello
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | | | - Jorge L Ruas
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Wen Fury
- Regeneron Pharmaceuticals, Tarrytown, 10591, NY, USA
| | - Yu Bai
- Regeneron Pharmaceuticals, Tarrytown, 10591, NY, USA
| | | | - Roberta Sartori
- Venetian Institute of Molecular Medicine, 35131, Padova, Italy.,Department of Biomedical Sciences, University of Padova, 35131, Padova, Italy
| | - Denis C Guttridge
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Medical Centre, Columbus, 43210, OH, USA
| | - Marco Sandri
- Venetian Institute of Molecular Medicine, 35131, Padova, Italy.,Department of Biomedical Sciences, University of Padova, 35131, Padova, Italy
| | - Lars Larsson
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden.,Department of Clinical Neuroscience, Clinical Neurophysiology, Karolinska Institutet, SE-171 77, Stockholm, Sweden.,Department of Biobehavioral Health, The Pennsylvania State University, University Park, PA, USA
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42
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Boutry C, El-Kadi SW, Suryawan A, Steinhoff-Wagner J, Stoll B, Orellana RA, Nguyen HV, Kimball SR, Fiorotto ML, Davis TA. Pulsatile delivery of a leucine supplement during long-term continuous enteral feeding enhances lean growth in term neonatal pigs. Am J Physiol Endocrinol Metab 2016; 310:E699-E713. [PMID: 26884386 PMCID: PMC4835946 DOI: 10.1152/ajpendo.00479.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 02/09/2016] [Indexed: 01/06/2023]
Abstract
Neonatal pigs are used as a model to study and optimize the clinical treatment of infants who are unable to maintain oral feeding. Using this model, we have shown previously that pulsatile administration of leucine during continuous feeding over 24 h via orogastric tube enhanced protein synthesis in skeletal muscle compared with continuous feeding alone. To determine the long-term effects of leucine pulses, neonatal piglets (n = 11-12/group) were continuously fed formula via orogastric tube for 21 days, with an additional parenteral infusion of either leucine (CON + LEU; 800 μmol·kg-1·h-1) or alanine (CON + ALA) for 1 h every 4 h. The results show that body and muscle weights and lean gain were ∼25% greater, and fat gain was 48% lower in CON + LEU than CON + ALA; weights of other tissues were unaffected by treatment. Fractional protein synthesis rates in longissimus dorsi, gastrocnemius, and soleus muscles were ∼30% higher in CON + LEU compared with CON + ALA and were associated with decreased Deptor abundance and increased mTORC1, mTORC2, 4E-BP1, and S6K1 phosphorylation, SNAT2 abundance, and association of eIF4E with eIF4G and RagC with mTOR. There were no treatment effects on PKB, eIF2α, eEF2, or PRAS40 phosphorylation, Rheb, SLC38A9, v-ATPase, LAMTOR1, LAMTOR2, RagA, RagC, and LAT1 abundance, the proportion of polysomes to nonpolysomes, or the proportion of mRNAs encoding rpS4 or rpS8 associated with polysomes. Our results demonstrate that pulsatile delivery of a leucine supplement during 21 days of continuous enteral feeding enhances lean growth by stimulating the mTORC1-dependent translation initiation pathway, leading to protein synthesis in skeletal muscle of neonates.
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Affiliation(s)
- Claire Boutry
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas; and
| | - Samer W El-Kadi
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas; and
| | - Agus Suryawan
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas; and
| | - Julia Steinhoff-Wagner
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas; and
| | - Barbara Stoll
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas; and
| | - Renán A Orellana
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas; and
| | - Hanh V Nguyen
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas; and
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Marta L Fiorotto
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas; and
| | - Teresa A Davis
- United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas; and
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43
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Kalamgi RC, Larsson L. Mechanical Signaling in the Pathophysiology of Critical Illness Myopathy. Front Physiol 2016; 7:23. [PMID: 26869939 PMCID: PMC4740381 DOI: 10.3389/fphys.2016.00023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/18/2016] [Indexed: 12/14/2022] Open
Abstract
The complete loss of mechanical stimuli of skeletal muscles, i.e., the loss of external strain, related to weight bearing, and internal strain, related to the contraction of muscle cells, is uniquely observed in pharmacologically paralyzed or deeply sedated mechanically ventilated intensive care unit (ICU) patients. The preferential loss of myosin and myosin associated proteins in limb and trunk muscles is a significant characteristic of critical illness myopathy (CIM) which separates CIM from other types of acquired muscle weaknesses in ICU patients. Mechanical silencing is an important factor triggering CIM. Microgravity or ground based microgravity models form the basis of research on the effect of muscle unloading-reloading, but the mechanisms and effects may differ from the ICU conditions. In order to understand how mechanical tension regulates muscle mass, it is critical to know how muscles sense mechanical information and convert stimulus to intracellular biochemical actions and changes in gene expression, a process called cellular mechanotransduction. In adult skeletal muscles and muscle fibers, this process may differ, the same stimulus can cause divergent response and the same fiber type may undergo opposite changes in different muscles. Skeletal muscle contains multiple types of mechano-sensors and numerous structures that can be affected differently and hence respond differently in distinct muscles.
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Affiliation(s)
- Rebeca C Kalamgi
- Basic and Clinical Muscle Biology, Department of Physiology and Pharmacology, Karolinska Institutet Stockholm, Sweden
| | - Lars Larsson
- Basic and Clinical Muscle Biology, Department of Physiology and Pharmacology, Karolinska InstitutetStockholm, Sweden; Department of Clinical Neuroscience, Clinical Neurophysiology, Karolinska InstitutetStockholm, Sweden
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44
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McLeod M, Breen L, Hamilton DL, Philp A. Live strong and prosper: the importance of skeletal muscle strength for healthy ageing. Biogerontology 2016; 17:497-510. [PMID: 26791164 PMCID: PMC4889643 DOI: 10.1007/s10522-015-9631-7] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 12/22/2015] [Indexed: 12/19/2022]
Abstract
Due to improved health care, diet and infrastructure in developed countries, since 1840 life expectancy has increased by approximately 2 years per decade. Accordingly, by 2050, a quarter of Europe’s population will be over 65 years, representing a 10 % rise in half a century. With this rapid rise comes an increased prevalence of diseases of ageing and associated healthcare expenditure. To address the health consequences of global ageing, research in model systems (worms, flies and mice) has indicated that reducing the rate of organ growth, via reductions in protein synthetic rates, has multi-organ health benefits that collectively lead to improvements in lifespan. In contrast, human pre-clinical, clinical and large cohort prospective studies demonstrate that ageing leads to anabolic (i.e. growth) impairments in skeletal muscle, which in turn leads to reductions in muscle mass and strength, factors directly associated with mortality rates in the elderly. As such, increasing muscle protein synthesis via exercise or protein-based nutrition maintains a strong, healthy muscle mass, which in turn leads to improved health, independence and functionality. The aim of this review is to critique current literature relating to the maintenance of muscle mass across lifespan and discuss whether maintaining or reducing protein synthesis is the most logical approach to support musculoskeletal function and by extension healthy human ageing.
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Affiliation(s)
- Michael McLeod
- MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Birmingham, B15 2TT, UK.,School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Leigh Breen
- MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Birmingham, B15 2TT, UK.,School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | | | - Andrew Philp
- MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Birmingham, B15 2TT, UK. .,School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
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45
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West DWD, Baehr LM, Marcotte GR, Chason CM, Tolento L, Gomes AV, Bodine SC, Baar K. Acute resistance exercise activates rapamycin-sensitive and -insensitive mechanisms that control translational activity and capacity in skeletal muscle. J Physiol 2015; 594:453-68. [PMID: 26548696 DOI: 10.1113/jp271365] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 10/29/2015] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS Ribosome biogenesis is the primary determinant of translational capacity, but its regulation in skeletal muscle following acute resistance exercise is poorly understood. Resistance exercise increases muscle protein synthesis acutely, and muscle mass with training, but the role of translational capacity in these processes is unclear. Here, we show that acute resistance exercise activated pathways controlling translational activity and capacity through both rapamycin-sensitive and -insensitive mechanisms. Transcription factor c-Myc and its downstream targets, which are known to regulate ribosome biogenesis in other cell types, were upregulated after resistance exercise in a rapamycin-independent manner and may play a role in determining translational capacity in skeletal muscle. Local inhibition of myostatin was also not affected by rapamycin and may contribute to the rapamycin-independent effects of resistance exercise. ABSTRACT This study aimed to determine (1) the effect of acute resistance exercise on mechanisms of ribosome biogenesis, and (2) the impact of mammalian target of rapamycin on ribosome biogenesis, and muscle protein synthesis (MPS) and degradation. Female F344BN rats underwent unilateral electrical stimulation of the sciatic nerve to mimic resistance exercise in the tibialis anterior (TA) muscle. TA muscles were collected at intervals over the 36 h of exercise recovery (REx); separate groups of animals were administered rapamycin pre-exercise (REx+Rapamycin). Resistance exercise led to a prolonged (6-36 h) elevation (30-50%) of MPS that was fully blocked by rapamycin at 6 h but only partially at 18 h. REx also altered pathways that regulate protein homeostasis and mRNA translation in a manner that was both rapamycin-sensitive (proteasome activity; phosphorylation of S6K1 and rpS6) and rapamycin-insensitive (phosphorylation of eEF2, ERK1/2 and UBF; gene expression of the myostatin target Mighty as well as c-Myc and its targets involved in ribosome biogenesis). The role of c-Myc was tested in vitro using the inhibitor 10058-F4, which, over time, decreased basal RNA and MPS in a dose-dependent manner (correlation of RNA and MPS, r(2) = 0.98), even though it had no effect on the acute stimulation of protein synthesis. In conclusion, acute resistance exercise stimulated rapamycin-sensitive and -insensitive mechanisms that regulate translation activity and capacity.
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Affiliation(s)
- Daniel W D West
- Department of Physiology & Membrane Biology, University of California Davis, Davis, CA, USA
| | - Leslie M Baehr
- Department of Physiology & Membrane Biology, University of California Davis, Davis, CA, USA
| | - George R Marcotte
- Department of Physiology & Membrane Biology, University of California Davis, Davis, CA, USA
| | - Courtney M Chason
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
| | - Luis Tolento
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
| | - Aldrin V Gomes
- Department of Physiology & Membrane Biology, University of California Davis, Davis, CA, USA.,Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
| | - Sue C Bodine
- Department of Physiology & Membrane Biology, University of California Davis, Davis, CA, USA.,Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA.,VA Northern California Health Care System, Mather, CA, USA
| | - Keith Baar
- Department of Physiology & Membrane Biology, University of California Davis, Davis, CA, USA.,Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA.,VA Northern California Health Care System, Mather, CA, USA
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46
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Tan HWS, Sim AYL, Huang SL, Leng Y, Long YC. HC toxin (a HDAC inhibitor) enhances IRS1-Akt signalling and metabolism in mouse myotubes. J Mol Endocrinol 2015; 55:197-207. [PMID: 26373795 DOI: 10.1530/jme-15-0140] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/14/2015] [Indexed: 01/04/2023]
Abstract
Exercise enhances numerous signalling pathways and activates substrate metabolism in skeletal muscle. Small molecule compounds that activate these cellular responses have been shown to recapitulate the metabolic benefits of exercise. In this study, a histone deacetylase (HDAC) inhibitor, HC toxin, was investigated as a small molecule compound that activates exercise-induced adaptations. In C2C12 myotubes, HC toxin treatment activated two exercise-stimulated pathways: AMP-activated protein kinase (AMPK) and Akt pathways. HC toxin increased the protein content and phosphorylation of insulin receptor substrate 1 as well as the activation of downstream Akt signalling. The effects of HC toxin on IRS1-Akt signalling were PI3K-dependent as wortmannin abolishes its effects on IRS1 protein accumulation and Akt phosphorylation. HC toxin-induced Akt activation was sufficient to enhance downstream mTOR complex 1 (mTORC1) signalling including p70S6K and S6, which were consistently abolished by PI3K inhibition. Insulin-stimulated glucose uptake, glycolysis, mitochondrial respiration and fatty acid oxidation were also enhanced in HC toxin-treated myotubes. When myotubes were challenged with serum starvation for the induction of atrophy, HC toxin treatment prevented the induction of genes that are involved in autophagy and proteasomal proteolysis. Conversely, IRS1-Akt signalling was not induced by HC toxin in several hepatoma cell lines, providing evidence for a favourable safety profile of this small molecule. These data highlight the potential of HDAC inhibitors as a novel class of small molecules for the induction of exercise-like signalling pathways and metabolism.
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Affiliation(s)
- Hayden Weng Siong Tan
- Department of BiochemistryYong Loo Lin School of Medicine, National University of Singapore, Block MD 7, 8 Medical Drive, #03-08, Singapore 117597, SingaporeState Key Laboratory of Drug ResearchShanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Arthur Yi Loong Sim
- Department of BiochemistryYong Loo Lin School of Medicine, National University of Singapore, Block MD 7, 8 Medical Drive, #03-08, Singapore 117597, SingaporeState Key Laboratory of Drug ResearchShanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Su Ling Huang
- Department of BiochemistryYong Loo Lin School of Medicine, National University of Singapore, Block MD 7, 8 Medical Drive, #03-08, Singapore 117597, SingaporeState Key Laboratory of Drug ResearchShanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ying Leng
- Department of BiochemistryYong Loo Lin School of Medicine, National University of Singapore, Block MD 7, 8 Medical Drive, #03-08, Singapore 117597, SingaporeState Key Laboratory of Drug ResearchShanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Yun Chau Long
- Department of BiochemistryYong Loo Lin School of Medicine, National University of Singapore, Block MD 7, 8 Medical Drive, #03-08, Singapore 117597, SingaporeState Key Laboratory of Drug ResearchShanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
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47
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da Rocha AL, Pereira BC, Pauli JR, de Souza CT, Teixeira GR, Lira FS, Cintra DE, Ropelle ER, Júnior CR, da Silva AS. Downhill Running Excessive Training Inhibits Hypertrophy in Mice Skeletal Muscles with Different Fiber Type Composition. J Cell Physiol 2015; 231:1045-56. [DOI: 10.1002/jcp.25197] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/16/2015] [Indexed: 02/06/2023]
Affiliation(s)
- Alisson L. da Rocha
- Postgraduate Program in Rehabilitation and Functional Performance; Ribeirão Preto Medical School; University of São Paulo (USP); Ribeirão Preto São Paulo Brazil
| | - Bruno C. Pereira
- Postgraduate Program in Rehabilitation and Functional Performance; Ribeirão Preto Medical School; University of São Paulo (USP); Ribeirão Preto São Paulo Brazil
| | - José R. Pauli
- Sport Sciences Course; Faculty of Applied Sciences; State University of Campinas (UNICAMP); Limeira São Paulo Brazil
| | - Claudio T. de Souza
- Exercise Biochemistry and Physiology Laboratory Postgraduate Program in Health Sciences; Health Sciences Unit; University of Far Southern Santa Catarina; Criciúma Santa Catarina Brazil
| | - Giovana R. Teixeira
- Department of Physical Education; State University of São Paulo (UNESP); Presidente Prudente São Paulo Brazil
| | - Fábio S. Lira
- Department of Physical Education; State University of São Paulo (UNESP); Presidente Prudente São Paulo Brazil
| | - Dennys E. Cintra
- Sport Sciences Course; Faculty of Applied Sciences; State University of Campinas (UNICAMP); Limeira São Paulo Brazil
| | - Eduardo R. Ropelle
- Sport Sciences Course; Faculty of Applied Sciences; State University of Campinas (UNICAMP); Limeira São Paulo Brazil
| | - Carlos R.B. Júnior
- School of Physical Education and Sport of Ribeirão Preto; USP; Ribeirão Preto São Paulo Brazil
| | - Adelino S.R. da Silva
- Postgraduate Program in Rehabilitation and Functional Performance; Ribeirão Preto Medical School; University of São Paulo (USP); Ribeirão Preto São Paulo Brazil
- School of Physical Education and Sport of Ribeirão Preto; USP; Ribeirão Preto São Paulo Brazil
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48
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Gonzalez AM, Hoffman JR, Jajtner AR, Townsend JR, Boone CH, Beyer KS, Baker KM, Wells AJ, Church DD, Mangine GT, Oliveira LP, Moon JR, Fukuda DH, Stout JR. Protein supplementation does not alter intramuscular anabolic signaling or endocrine response after resistance exercise in trained men. Nutr Res 2015; 35:990-1000. [PMID: 26428621 DOI: 10.1016/j.nutres.2015.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 09/04/2015] [Accepted: 09/08/2015] [Indexed: 12/31/2022]
Abstract
The mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway appears to be the primary regulator of muscle protein synthesis. A variety of stimuli including resistance exercise, amino acids, and hormonal signals activate mTORC1 signaling. The purpose of this study was to investigate the effect of a protein supplement on mTORC1 signaling following a resistance exercise protocol designed to promote elevations in circulating hormone concentrations. We hypothesized that the protein supplement would augment the intramuscular anabolic signaling response. Ten resistance-trained men (age, 24.7 ± 3.4 years; weight, 90.1 ± 11.3 kg; height, 176.0 ± 4.9 cm) received either a placebo or a supplement containing 20 g protein, 6 g carbohydrates, and 1 g fat after high-volume, short-rest lower-body resistance exercise. Blood samples were obtained at baseline, immediately, 30 minutes, 1 hour, 2 hours, and 5 hours after exercise. Fine-needle muscle biopsies were completed at baseline, 1 hour, and 5 hours after exercise. Myoglobin, lactate dehydrogenase, and lactate concentrations were significantly elevated after resistance exercise (P < .0001); however, no differences were observed between trials. Resistance exercise also elicited a significant insulin, growth hormone, and cortisol response (P < .01); however, no differences were observed between trials for insulin-like growth factor-1, insulin, testosterone, growth hormone, or cortisol. Intramuscular anabolic signaling analysis revealed significant elevations in RPS6 phosphorylation after resistance exercise (P = .001); however, no differences were observed between trials for signaling proteins including Akt, mTOR, p70S6k, and RPS6. The endocrine response and phosphorylation status of signaling proteins within the mTORC1 pathway did not appear to be altered by ingestion of supplement after resistance exercise in resistance-trained men.
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Affiliation(s)
- Adam M Gonzalez
- Department of Health Professions, Hofstra University, Hempstead, NY, USA
| | - Jay R Hoffman
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA.
| | - Adam R Jajtner
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
| | - Jeremy R Townsend
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
| | - Carleigh H Boone
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
| | - Kyle S Beyer
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
| | - Kayla M Baker
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
| | - Adam J Wells
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
| | - David D Church
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
| | - Gerald T Mangine
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
| | - Leonardo P Oliveira
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA; Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Jordan R Moon
- Sports Science Institute, MusclePharm, Corp, Denver, CO, USA
| | - David H Fukuda
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
| | - Jeffrey R Stout
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, USA
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49
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Kinugawa S, Takada S, Matsushima S, Okita K, Tsutsui H. Skeletal Muscle Abnormalities in Heart Failure. Int Heart J 2015; 56:475-84. [PMID: 26346520 DOI: 10.1536/ihj.15-108] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Exercise capacity is lowered in patients with heart failure, which limits their daily activities and also reduces their quality of life. Furthermore, lowered exercise capacity has been well demonstrated to be closely related to the severity and prognosis of heart failure. Skeletal muscle abnormalities including abnormal energy metabolism, transition of myofibers from type I to type II, mitochondrial dysfunction, reduction in muscular strength, and muscle atrophy have been shown to play a central role in lowered exercise capacity. The skeletal muscle abnormalities can be classified into the following main types: 1) low endurance due to mitochondrial dysfunction; and 2) low muscle mass and muscle strength due to imbalance of protein synthesis and degradation. The molecular mechanisms of these skeletal muscle abnormalities have been studied mainly using animal models. The current review including our recent study will focus upon the skeletal muscle abnormalities in heart failure.
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Affiliation(s)
- Shintaro Kinugawa
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine
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50
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Gonzalez AM, Hoffman JR, Townsend JR, Jajtner AR, Boone CH, Beyer KS, Baker KM, Wells AJ, Mangine GT, Robinson EH, Church DD, Oliveira LP, Willoughby DS, Fukuda DH, Stout JR. Intramuscular anabolic signaling and endocrine response following high volume and high intensity resistance exercise protocols in trained men. Physiol Rep 2015. [PMID: 26197935 PMCID: PMC4552541 DOI: 10.14814/phy2.12466] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Resistance exercise paradigms are often divided into high volume (HV) or high intensity (HI) protocols, however, it is unknown whether these protocols differentially stimulate mTORC1 signaling. The purpose of this study was to examine mTORC1 signaling in conjunction with circulating hormone concentrations following a typical HV and HI lower-body resistance exercise protocol. Ten resistance-trained men (24.7 ± 3.4 years; 90.1 ± 11.3 kg; 176.0 ± 4.9 cm) performed each resistance exercise protocol in a random, counterbalanced order. Blood samples were obtained at baseline (BL), immediately (IP), 30 min (30P), 1 h (1H), 2 h (2H), and 5 h (5H) postexercise. Fine needle muscle biopsies were completed at BL, 1H, and 5H. Electromyography of the vastus lateralis was also recorded during each protocol. HV and HI produced a similar magnitude of muscle activation across sets. Myoglobin and lactate dehydrogenase concentrations were significantly greater following HI compared to HV (P = 0.01–0.02), whereas the lactate response was significantly higher following HV compared to HI (P = 0.003). The growth hormone, cortisol, and insulin responses were significantly greater following HV compared to HI (P = 0.0001–0.04). No significant differences between protocols were observed for the IGF-1 or testosterone response. Intramuscular anabolic signaling analysis revealed a significantly greater (P = 0.03) phosphorylation of IGF-1 receptor at 1H following HV compared to HI. Phosphorylation status of all other signaling proteins including mTOR, p70S6k, and RPS6 were not significantly different between trials. Despite significant differences in markers of muscle damage and the endocrine response following HV and HI, both protocols appeared to elicit similar mTORC1 activation in resistance-trained men.
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Affiliation(s)
- Adam M Gonzalez
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Jay R Hoffman
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Jeremy R Townsend
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Adam R Jajtner
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Carleigh H Boone
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Kyle S Beyer
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Kayla M Baker
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Adam J Wells
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Gerald T Mangine
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Edward H Robinson
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - David D Church
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Leonardo P Oliveira
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Darryn S Willoughby
- Exercise and Biochemical Nutrition Laboratory, Baylor University, Waco, Texas, USA
| | - David H Fukuda
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
| | - Jeffrey R Stout
- Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, Florida, USA
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