1
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Zhang Q, Halle JL, Counts BR, Pi M, Carson JA. mTORC1 and BMP-Smad1/5 regulation of serum-stimulated myotube hypertrophy: a role for autophagy. Am J Physiol Cell Physiol 2024; 327:C124-C139. [PMID: 38766767 PMCID: PMC11371323 DOI: 10.1152/ajpcell.00237.2024] [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: 04/11/2024] [Revised: 05/14/2024] [Accepted: 05/14/2024] [Indexed: 05/22/2024]
Abstract
Protein synthesis regulation is critical for skeletal muscle hypertrophy, yet other established cellular processes are necessary for growth-related cellular remodeling. Autophagy has a well-acknowledged role in muscle quality control, but evidence for its role in myofiber hypertrophy remains equivocal. Both mammalian target of rapamycin complex I (mTORC1) and bone morphogenetic protein (BMP)-Smad1/5 (Sma and Mad proteins from Caenorhabditis elegans and Drosophila, respectively) signaling are reported regulators of myofiber hypertrophy; however, gaps remain in our understanding of how this regulation is integrated with growth processes and autophagy regulation. Therefore, we investigated the mTORC1 and Smad1/5 regulation of protein synthesis and autophagy flux during serum-stimulated myotube growth. Chronic serum stimulation experiments were performed on day 5 differentiated C2C12 myotubes incubated in differentiation medium [2% horse serum (HS)] or growth medium [5% fetal bovine serum (FBS)] for 48 h. Rapamycin or LDN193189 was dosed for 48 h to inhibit mTORC1 and BMP-Smad1/5 signaling, respectively. Acute serum stimulation was examined in day 7 differentiated myotubes. Protein synthesis was measured by puromycin incorporation. Bafilomycin A1 and immunoblotting for LC3B were used to assess autophagy flux. Chronic serum stimulation increased myotube diameter 22%, total protein 21%, total RNA 100%, and Smad1/5 phosphorylation 404% and suppressed autophagy flux. Rapamycin, but not LDN193189, blocked serum-induced myotube hypertrophy and the increase in total RNA. Acute serum stimulation increased protein synthesis 111%, Smad1/5 phosphorylation 559%, and rpS6 phosphorylation 117% and suppressed autophagy flux. Rapamycin increased autophagy flux during acute serum stimulation. These results provide evidence for mTORC1, but not BMP-Smad1/5, signaling being required for serum-induced myotube hypertrophy and autophagy flux by measuring LC3BII/I expression. Further investigation is warranted to examine the role of autophagy flux in myotube hypertrophy.NEW & NOTEWORTHY The present study demonstrates that myotube hypertrophy caused by chronic serum stimulation requires mammalian target of rapamycin complex 1 (mTORC1) signaling but not bone morphogenetic protein (BMP)-Smad1/5 signaling. The suppression of autophagy flux was associated with serum-induced myotube hypertrophy and mTORC1 regulation of autophagy flux by measuring LC3BII/I expression. Rapamycin is widely investigated for beneficial effects in aging skeletal muscle and sarcopenia; our results provide evidence that rapamycin can regulate autophagy-related signaling during myotube growth, which could benefit skeletal muscle functional and metabolic health.
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Affiliation(s)
- Quan Zhang
- Integrative Muscle Biology Laboratory, Division of Rehabilitation Sciences, College of Health ProfessionsUniversity of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Jessica L Halle
- Integrative Muscle Biology Laboratory, Division of Rehabilitation Sciences, College of Health ProfessionsUniversity of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Brittany R Counts
- Integrative Muscle Biology Laboratory, Division of Rehabilitation Sciences, College of Health ProfessionsUniversity of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Min Pi
- Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - James A Carson
- Huffines Institute for Sports Medicine & Human Performance, Department of Kinesiology & Sports Management , Texas A&M University, College Station, Texas, United States
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2
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Brown A, Parise G, Thomas ACQ, Ng SY, McGlory C, Phillips SM, Kumbhare D, Joanisse S. Low baseline ribosome-related gene expression and resistance training-induced declines in ribosome-related gene expression are associated with skeletal muscle hypertrophy in young men and women. J Cell Physiol 2024; 239:e31182. [PMID: 38214457 DOI: 10.1002/jcp.31182] [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: 07/14/2023] [Revised: 12/04/2023] [Accepted: 12/12/2023] [Indexed: 01/13/2024]
Abstract
Ribosomes are essential cellular machinery for protein synthesis. It is hypothesised that ribosome content supports muscle growth and that individuals with more ribosomes have greater increases in muscle size following resistance training (RT). Aerobic conditioning (AC) also elicits distinct physiological adaptations; however, no measures of ribosome content following AC have been conducted. We used ribosome-related gene expression as a proxy measure for ribosome content and hypothesised that AC and RT would increase ribosome-related gene expression. Fourteen young men and women performed 6 weeks of single-legged AC followed by 10 weeks of double-legged RT. Muscle biopsies were taken following AC and following RT in the aerobically conditioned (AC+RT) and unconditioned (RT) legs. No differences in regulatory genes (Ubf, Cyclin D1, Tif-1a and Polr-1b) involved in ribosomal biogenesis or ribosomal RNA (45S, 5.8S, 18S and 28S rRNAs) expression were observed following AC and RT, except for c-Myc (RT > AC+RT) and 5S rRNA (RT < AC+RT at pre-RT) with 18S external transcribed spacer and 5.8S internal transcribed spacer expression decreasing from pre-RT to post-RT in the RT leg only. When divided for change in leg-lean soft tissue mass (ΔLLSTM) following RT, legs with the greatest ΔLLSTM had lower expression in 11/13 measured ribosome-related genes before RT and decreased expression in 9/13 genes following RT. These results indicate that AC and RT did not increase ribosome-related gene expression. Contrary to previous research, the greatest increase in muscle mass was associated with lower changes in ribosome-related gene expression over the course of the 10-week training programme. This may point to the importance of translational efficiency rather than translational capacity (i.e. ribosome content) in mediating long-term exercise-induced adaptations in skeletal muscle.
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Affiliation(s)
- Alex Brown
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Gianni Parise
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Aaron C Q Thomas
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Sean Y Ng
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Chris McGlory
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Stuart M Phillips
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Dinesh Kumbhare
- Toronto Rehabilitation Institute, University of Toronto, Toronto, Ontario, Canada
| | - Sophie Joanisse
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
- Institute of Sport, Manchester Metropolitan University, Manchester, UK
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, Nottingha, UK
- School of Life Sciences, University of Nottingham, Nottingham, UK
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3
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McColl TJ, Clarke DC. Kinetic modeling of leucine-mediated signaling and protein metabolism in human skeletal muscle. iScience 2024; 27:108634. [PMID: 38188514 PMCID: PMC10767222 DOI: 10.1016/j.isci.2023.108634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 11/15/2023] [Accepted: 12/01/2023] [Indexed: 01/09/2024] Open
Abstract
Skeletal muscle protein levels are governed by the relative rates of muscle protein synthesis (MPS) and breakdown (MPB). The mechanisms controlling these rates are complex, and their integrated behaviors are challenging to study through experiments alone. The purpose of this study was to develop and analyze a kinetic model of leucine-mediated mTOR signaling and protein metabolism in the skeletal muscle of young adults. Our model amalgamates published cellular-level models of the IRS1-PI3K-Akt-mTORC1 signaling system and of skeletal-muscle leucine kinetics with physiological-level models of leucine digestion and transport and insulin dynamics. The model satisfactorily predicts experimental data from diverse leucine feeding protocols. Model analysis revealed that total levels of p70S6K are a primary determinant of MPS, insulin signaling substantially affects muscle net protein balance via its effects on MPB, and p70S6K-mediated feedback of mTORC1 signaling reduces MPS in a dose-dependent manner.
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Affiliation(s)
- Taylor J. McColl
- Department of Biomedical Physiology and KinesiologySimon Fraser University, Burnaby, BC V5A 1S6, Canada
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - David C. Clarke
- Department of Biomedical Physiology and KinesiologySimon Fraser University, Burnaby, BC V5A 1S6, Canada
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
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4
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Perez ÉS, Duran BOS, Zanella BTT, Dal-Pai-Silva M. Review: Understanding fish muscle biology in the indeterminate growth species pacu (Piaractus mesopotamicus). Comp Biochem Physiol A Mol Integr Physiol 2023; 285:111502. [PMID: 37572733 DOI: 10.1016/j.cbpa.2023.111502] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/14/2023]
Abstract
The muscle phenotype of fish is regulated by numerous factors that, although widely explored, still need to be fully understood. In this context, several studies aimed to unravel how internal and external stimuli affect the muscle growth of these vertebrates. The pacu (Piaractus mesopotamicus) is a species of indeterminate muscular growth that quickly reaches high body weight. For this reason, it adds great importance to the productive sector, along with other round fish. In this context, we aimed to compile studies on fish biology and skeletal muscle growth, focusing on studies by our research group that used pacu as an experimental model along with other species. Based on these studies, new muscle phenotype regulators were identified and explored in vivo, in vitro, and in silico studies, which strongly contribute to advances in understanding muscle growth mechanisms with future applications in the productive sector.
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Affiliation(s)
- Érika Stefani Perez
- Department of Structural and Functional Biology, Institute of Bioscience of Botucatu, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil.
| | - Bruno Oliveira Silva Duran
- Department of Histology, Embryology and Cell Biology, Institute of Biological Sciences, Federal University of Goiás (UFG), Goiânia, Goiás, Brazil.
| | - Bruna Tereza Thomazini Zanella
- Department of Structural and Functional Biology, Institute of Bioscience of Botucatu, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil.
| | - Maeli Dal-Pai-Silva
- Department of Structural and Functional Biology, Institute of Bioscience of Botucatu, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil.
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Roberts MD, McCarthy JJ, Hornberger TA, Phillips SM, Mackey AL, Nader GA, Boppart MD, Kavazis AN, Reidy PT, Ogasawara R, Libardi CA, Ugrinowitsch C, Booth FW, Esser KA. Mechanisms of mechanical overload-induced skeletal muscle hypertrophy: current understanding and future directions. Physiol Rev 2023; 103:2679-2757. [PMID: 37382939 PMCID: PMC10625844 DOI: 10.1152/physrev.00039.2022] [Citation(s) in RCA: 39] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 06/12/2023] [Accepted: 06/21/2023] [Indexed: 06/30/2023] Open
Abstract
Mechanisms underlying mechanical overload-induced skeletal muscle hypertrophy have been extensively researched since the landmark report by Morpurgo (1897) of "work-induced hypertrophy" in dogs that were treadmill trained. Much of the preclinical rodent and human resistance training research to date supports that involved mechanisms include enhanced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, an expansion in translational capacity through ribosome biogenesis, increased satellite cell abundance and myonuclear accretion, and postexercise elevations in muscle protein synthesis rates. However, several lines of past and emerging evidence suggest that additional mechanisms that feed into or are independent of these processes are also involved. This review first provides a historical account of how mechanistic research into skeletal muscle hypertrophy has progressed. A comprehensive list of mechanisms associated with skeletal muscle hypertrophy is then outlined, and areas of disagreement involving these mechanisms are presented. Finally, future research directions involving many of the discussed mechanisms are proposed.
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Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - John J McCarthy
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States
| | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Stuart M Phillips
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Abigail L Mackey
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital-Bispebjerg and Frederiksberg, and Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Gustavo A Nader
- Department of Kinesiology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - Marni D Boppart
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
| | - Andreas N Kavazis
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Paul T Reidy
- Department of Kinesiology, Nutrition and Health, Miami University, Oxford, Ohio, United States
| | - Riki Ogasawara
- Healthy Food Science Research Group, Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Cleiton A Libardi
- MUSCULAB-Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of São Carlos, São Carlos, Brazil
| | - Carlos Ugrinowitsch
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Frank W Booth
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, United States
| | - Karyn A Esser
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, Florida, United States
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6
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Ferreira RP, Duarte JA. Protein Turnover in Skeletal Muscle: Looking at Molecular Regulation towards an Active Lifestyle. Int J Sports Med 2023; 44:763-777. [PMID: 36854391 DOI: 10.1055/a-2044-8277] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Skeletal muscle is a highly plastic tissue, able to change its mass and functional properties in response to several stimuli. Skeletal muscle mass is influenced by the balance between protein synthesis and breakdown, which is regulated by several signaling pathways. The relative contribution of Akt/mTOR signaling, ubiquitin-proteasome pathway, autophagy among other signaling pathways to protein turnover and, therefore, to skeletal muscle mass, differs depending on the wasting or loading condition and muscle type. By modulating mitochondria biogenesis, PGC-1α has a major role in the cell's bioenergetic status and, thus, on protein turnover. In fact, rates of protein turnover regulate differently the levels of distinct protein classes in response to atrophic or hypertrophic stimuli. Mitochondrial protein turnover rates may be enhanced in wasting conditions, whereas the increased turnover of myofibrillar proteins triggers muscle mass gain. The present review aims to update the knowledge on the molecular pathways implicated in the regulation of protein turnover in skeletal muscle, focusing on how distinct muscle proteins may be modulated by lifestyle interventions with emphasis on exercise training. The comprehensive analysis of the anabolic effects of exercise programs will pave the way to the tailored management of muscle wasting conditions.
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Affiliation(s)
- Rita Pinho Ferreira
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Aveiro, Portugal
| | - Jose Alberto Duarte
- TOXRUN - Toxicology Research Unit, University Institute of Health Sciences, CESPU, CRL, Gandra, Portugal
- CIAFEL, Faculty of Sports, University of Porto and Laboratory for Integrative and Translational Research in Population Health (ITR), Porto, Portugal
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7
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Halle JL, Counts BR, Paez HG, Baumfalk DR, Zhang Q, Mohamed JS, Glazer ES, Puppa MJ, Smuder AJ, Alway SE, Carson JA. Recovery from FOLFOX chemotherapy-induced systemic and skeletal muscle metabolic dysfunction in mice. Am J Physiol Endocrinol Metab 2023; 325:E132-E151. [PMID: 37378624 PMCID: PMC10393342 DOI: 10.1152/ajpendo.00096.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/22/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023]
Abstract
FOLFOX (5-fluorouracil, leucovorin, oxaliplatin) chemotherapy is used to treat colorectal cancer and can acutely induce metabolic dysfunction. However, the lasting effects on systemic and skeletal muscle metabolism after treatment cessation are poorly understood. Therefore, we investigated the acute and lasting effects of FOLFOX chemotherapy on systemic and skeletal muscle metabolism in mice. Direct effects of FOLFOX in cultured myotubes were also investigated. Male C57BL/6J mice completed four cycles (acute) of FOLFOX or PBS. Subsets were allowed to recover for 4 wk or 10 wk. Comprehensive Laboratory Animal Monitoring System (CLAMS) metabolic measurements were performed for 5 days before study endpoint. C2C12 myotubes were treated with FOLFOX for 24 hr. Acute FOLFOX attenuated body mass and body fat accretion independent of food intake or cage activity. Acute FOLFOX decreased blood glucose, oxygen consumption (V̇o2), carbon dioxide production (V̇co2), energy expenditure, and carbohydrate (CHO) oxidation. Deficits in V̇o2 and energy expenditure remained at 10 wk. CHO oxidation remained disrupted at 4 wk but returned to control levels after 10 wk. Acute FOLFOX reduced muscle COXIV enzyme activity, AMPK(T172), ULK1(S555), and LC3BII protein expression. Muscle LC3BII/I ratio was associated with altered CHO oxidation (r = 0.75, P = 0.03). In vitro, FOLFOX suppressed myotube AMPK(T172), ULK1(S555), and autophagy flux. Recovery for 4 wk normalized skeletal muscle AMPK and ULK1 phosphorylation. Our results provide evidence that FOLFOX disrupts systemic metabolism, which is not readily recoverable after treatment cessation. FOLFOX effects on skeletal muscle metabolic signaling did recover. Further investigations are warranted to prevent and treat FOLFOX-induced metabolic toxicities that negatively impact survival and life quality of patients with cancer.NEW & NOTEWORTHY The present study demonstrates that FOLFOX chemotherapy induces long-lasting deficits in systemic metabolism. Interestingly, FOLFOX modestly suppressed skeletal muscle AMPK and autophagy signaling in vivo and in vitro. The FOLFOX-induced suppression of muscle metabolic signaling recovered after treatment cessation, independent of systemic metabolic dysfunction. Future research should investigate if activating AMPK during treatment can prevent long-term toxicities to improve health and quality of life of patients with cancer and survivors.
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Affiliation(s)
- Jessica L Halle
- Integrative Muscle Biology Laboratory, Division of Regenerative and Rehabilitation Sciences, College of Health Professions, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Brittany R Counts
- Integrative Muscle Biology Laboratory, Division of Regenerative and Rehabilitation Sciences, College of Health Professions, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Hector G Paez
- Laboratory of Muscle Biology and Sarcopenia, Department of Physical Therapy, College of Health Professions, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Dryden R Baumfalk
- Department of Applied Physiology & Kinesiology, University of Florida, Gainesville, Florida, United States
| | - Quan Zhang
- Integrative Muscle Biology Laboratory, Division of Regenerative and Rehabilitation Sciences, College of Health Professions, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Junaith S Mohamed
- Laboratory of Muscle and Nerve, Department of Diagnostic and Health Sciences, College of Health Professions, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Evan S Glazer
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - Melissa J Puppa
- College of Health Sciences, The University of Memphis, Memphis, Tennessee, United States
| | - Ashley J Smuder
- Department of Applied Physiology & Kinesiology, University of Florida, Gainesville, Florida, United States
| | - Stephen E Alway
- Laboratory of Muscle Biology and Sarcopenia, Department of Physical Therapy, College of Health Professions, University of Tennessee Health Science Center, Memphis, Tennessee, United States
| | - James A Carson
- Integrative Muscle Biology Laboratory, Division of Regenerative and Rehabilitation Sciences, College of Health Professions, University of Tennessee Health Science Center, Memphis, Tennessee, United States
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8
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Martin RA, Keeler SP, Wu K, Shearon WJ, Patel D, Li J, Hoang M, Hoffmann CM, Hughes ME, Holtzman MJ. An alternative mechanism for skeletal muscle dysfunction in long-term post-viral lung disease. Am J Physiol Lung Cell Mol Physiol 2023; 324:L870-L878. [PMID: 37130808 PMCID: PMC10259859 DOI: 10.1152/ajplung.00338.2022] [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: 10/07/2022] [Revised: 04/10/2023] [Accepted: 05/02/2023] [Indexed: 05/04/2023] Open
Abstract
Chronic lung disease is often accompanied by disabling extrapulmonary symptoms, notably skeletal muscle dysfunction and atrophy. Moreover, the severity of respiratory symptoms correlates with decreased muscle mass and in turn lowered physical activity and survival rates. Previous models of muscle atrophy in chronic lung disease often modeled chronic obstructive pulmonary disease (COPD) and relied on cigarette smoke exposure and LPS stimulation, but these conditions independently affect skeletal muscle even without accompanying lung disease. Moreover, there is an emerging and pressing need to understand the extrapulmonary manifestations of long-term post-viral lung disease (PVLD) as found in COVID-19. Here, we examine the development of skeletal muscle dysfunction in the setting of chronic pulmonary disease caused by infection due to the natural pathogen Sendai virus using a mouse model of PVLD. We identify a significant decrease in myofiber size when PVLD is maximal at 49 days after infection. We find no change in the relative types of myofibers, but the greatest decrease in fiber size is localized to fast-twitch-type IIB myofibers based on myosin heavy chain immunostaining. Remarkably, all biomarkers of myocyte protein synthesis and degradation (total RNA, ribosomal abundance, and ubiquitin-proteasome expression) were stable throughout the acute infectious illness and chronic post-viral disease process. Together, the results demonstrate a distinct pattern of skeletal muscle dysfunction in a mouse model of long-term PVLD. The findings thereby provide new insights into prolonged limitations in exercise capacity in patients with chronic lung disease after viral infections and perhaps other types of lung injury.NEW & NOTEWORTHY Our study used a mouse model of post-viral lung disease to study the impact of chronic lung disease on skeletal muscle. The model reveals a decrease in myofiber size that is selective for specific types of myofibers and an alternative mechanism for muscle atrophy that might be independent of the usual markers of protein synthesis and degradation. The findings provide a basis for new therapeutic strategies to correct skeletal muscle dysfunction in chronic respiratory disease.
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Affiliation(s)
- Ryan A Martin
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
| | - Shamus P Keeler
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
| | - Kangyun Wu
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
| | - William J Shearon
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
| | - Devin Patel
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
| | - Jiajia Li
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
| | - My Hoang
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
| | - Christy M Hoffmann
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
| | - Michael E Hughes
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States
| | - Michael J Holtzman
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, United States
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9
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Chaillou T, Montiel-Rojas D. Does the blunted stimulation of skeletal muscle protein synthesis by aging in response to mechanical load result from impaired ribosome biogenesis? FRONTIERS IN AGING 2023; 4:1171850. [PMID: 37256189 PMCID: PMC10225510 DOI: 10.3389/fragi.2023.1171850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 05/04/2023] [Indexed: 06/01/2023]
Abstract
Age-related loss of skeletal muscle mass leads to a reduction of strength. It is likely due to an inadequate stimulation of muscle protein synthesis (MPS) in response to anabolic stimuli, such as mechanical load. Ribosome biogenesis is a major determinant of translational capacity and is essential for the control of muscle mass. This mini-review aims to put forth the hypothesis that ribosome biogenesis is impaired by aging in response to mechanical load, which could contribute to the age-related anabolic resistance and progressive muscle atrophy. Recent animal studies indicate that aging impedes muscle hypertrophic response to mechanical overload. This is associated with an impaired transcription of ribosomal DNA (rDNA) by RNA polymerase I (Pol I), a limited increase in total RNA concentration, a blunted activation of AKT/mTOR pathway, and an increased phosphorylation of AMPK. In contrast, an age-mediated impairment of ribosome biogenesis is unlikely in response to electrical stimulations. In human, the hypertrophic response to resistance exercise training is diminished with age. This is accompanied by a deficit in long-term MPS and an absence of increased total RNA concentration. The results addressing the acute response to resistance exercise suggest an impaired Pol I-mediated rDNA transcription and attenuated activation/expression of several upstream regulators of ribosome biogenesis in muscles from aged individuals. Altogether, emerging evidence indicates that impaired ribosome biogenesis could partly explain age-related anabolic resistance to mechanical load, which may ultimately contribute to progressive muscle atrophy. Future research should develop more advanced molecular tools to provide in-depth analysis of muscle ribosome biogenesis.
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10
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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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11
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Perez ÉS, Cury SS, Zanella BTT, Carvalho RF, Duran BOS, Dal-Pai-Silva M. Identification of Novel Genes Associated with Fish Skeletal Muscle Adaptation during Fasting and Refeeding Based on a Meta-Analysis. Genes (Basel) 2022; 13:genes13122378. [PMID: 36553644 PMCID: PMC9778430 DOI: 10.3390/genes13122378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
The regulation of the fish phenotype and muscle growth is influenced by fasting and refeeding periods, which occur in nature and are commonly applied in fish farming. However, the regulators associated with the muscle responses to these manipulations of food availability have not been fully characterized. We aimed to identify novel genes associated with fish skeletal muscle adaptation during fasting and refeeding based on a meta-analysis. Genes related to translational and proliferative machinery were investigated in pacus (Piaractus mesopotamicus) subjected to fasting (four and fifteen days) and refeeding (six hours, three and fifteen days). Our results showed that different fasting and refeeding periods modulate the expression of the genes mtor, rps27a, eef1a2, and cdkn1a. These alterations can indicate the possible protection of the muscle phenotype, in addition to adaptive responses that prioritize energy and substrate savings over cell division, a process regulated by ccnd1. Our study reveals the potential of meta-analysis for the identification of muscle growth regulators and provides new information on muscle responses to fasting and refeeding in fish that are of economic importance to aquaculture.
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Affiliation(s)
- Érika Stefani Perez
- Department of Structural and Functional Biology, São Paulo State University (UNESP), Botucatu 18618-689, Brazil
| | - Sarah Santiloni Cury
- Department of Structural and Functional Biology, São Paulo State University (UNESP), Botucatu 18618-689, Brazil
| | | | - Robson Francisco Carvalho
- Department of Structural and Functional Biology, São Paulo State University (UNESP), Botucatu 18618-689, Brazil
| | - Bruno Oliveira Silva Duran
- Department of Histology, Embryology and Cell Biology, Federal University of Goias (UFG), Goiania 74690-900, Brazil
| | - Maeli Dal-Pai-Silva
- Department of Structural and Functional Biology, São Paulo State University (UNESP), Botucatu 18618-689, Brazil
- Correspondence: ; Tel.: +55-(14)-3880-0470
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12
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Martin RA, Keeler SP, Wu K, Shearon WJ, Patel D, Hoang M, Hoffmann CM, Hughes ME, Holtzman MJ. An alternative mechanism for skeletal muscle dysfunction in long-term post-viral lung disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.10.07.511313. [PMID: 36238722 PMCID: PMC9558431 DOI: 10.1101/2022.10.07.511313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Chronic lung disease is often accompanied by disabling extrapulmonary symptoms, notably skeletal muscle dysfunction and atrophy. Moreover, the severity of respiratory symptoms correlates with decreased muscle mass and in turn lowered physical activity and survival rates. Previous models of muscle atrophy in chronic lung disease often modeled COPD and relied on cigarette smoke exposure and LPS-stimulation, but these conditions independently affect skeletal muscle even without accompanying lung disease. Moreover, there is an emerging and pressing need to understand the extrapulmonary manifestations of long-term post-viral lung disease (PVLD) as found in Covid-19. Here, we examine the development of skeletal muscle dysfunction in the setting of chronic pulmonary disease using a mouse model of PVLD caused by infection due to the natural pathogen Sendai virus. We identify a significant decrease in myofiber size when PVLD is maximal at 49 d after infection. We find no change in the relative types of myofibers, but the greatest decrease in fiber size is localized to fast-twitch type IIB myofibers based on myosin heavy chain immunostaining. Remarkably, all biomarkers of myocyte protein synthesis and degradation (total RNA, ribosomal abundance, and ubiquitin-proteasome expression) were stable throughout the acute infectious illness and chronic post-viral disease process. Together, the results demonstrate a distinct pattern of skeletal muscle dysfunction in a mouse model of long-term PVLD. The findings thereby provide new insight into prolonged limitations in exercise capacity in patients with chronic lung disease after viral infections and perhaps other types of lung injury.
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Affiliation(s)
- Ryan A. Martin
- Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110
| | - Shamus P. Keeler
- Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110
| | - Kangyun Wu
- Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110
| | - William J. Shearon
- Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110
| | - Devin Patel
- Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110
| | - My Hoang
- Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110
| | - Christy M. Hoffmann
- Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110
| | - Michael E. Hughes
- Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63110
| | - Michael J. Holtzman
- Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO 63110
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13
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Rozhkov SV, Sharlo KA, Shenkman BS, Mirzoev TM. Inhibition of mTORC1 differentially affects ribosome biogenesis in rat soleus muscle at the early and later stages of hindlimb unloading. Arch Biochem Biophys 2022; 730:109411. [PMID: 36155780 DOI: 10.1016/j.abb.2022.109411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/29/2022] [Accepted: 09/19/2022] [Indexed: 11/02/2022]
Abstract
Prolonged inactivity of skeletal muscles due to limb immobilization, bedrest, and exposure to microgravity results in a significant muscle atrophy. Inactivity-induced muscle atrophy is caused by a downregulation of protein synthesis (PS) and increased proteolysis. Mechanistic target of rapamycin complex 1 (mTORC1) is considered to be one of the main regulators of translational capacity (quantity of ribosomes), a key determinant of PS. Using a specific mTORC1 inhibitor (rapamycin) we aimed to determine if mTORC1 activity would influence ribosome biogenesis in rat soleus muscle at both early and later stages of mechanical unloading. Wistar rats were subjected to 1- and 7-day hindlimb suspension (HS) with and without rapamycin injections (1.5 mg/kg) and compared to weight-bearing control animals. The key markers of ribosome biogenesis were assessed by RT-PCR or agarose gel electrophoresis. The rate of PS was measured by SUnSET method. Both 1-day and 7-day HS resulted in a significant downregulation of ribosome biogenesis markers (c-Myc, 47S pre-rRNA, 18S + 28S rRNAs) and the rate of PS. Rapamycin administration during 1-day HS fully prevented a decrease in 47S pre-rRNA expression and amount of 18S + 28S rRNAs (without affecting c-Myc mRNA expression) and partially attenuated a decline in PS. Rapamycin treatment during 7-day HS significantly decreased p70S6K phosphorylation but failed to rescue a reduction in both the markers of ribosome biogenesis and the rate of PS. All together, our results suggest that mTORC1 inhibition at the initial (1 day), but not later (7 days) stage of HS can be beneficial for the maintenance of translational capacity (ribosome biogenesis) and the rate of PS in rat soleus muscle.
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Affiliation(s)
- Sergey V Rozhkov
- Myology Laboratory, Institute of Biomedical Problems RAS, 123007, 76A Khoroshevskoe shosse, Moscow, Russia
| | - Kristina A Sharlo
- Myology Laboratory, Institute of Biomedical Problems RAS, 123007, 76A Khoroshevskoe shosse, Moscow, Russia
| | - Boris S Shenkman
- Myology Laboratory, Institute of Biomedical Problems RAS, 123007, 76A Khoroshevskoe shosse, Moscow, Russia
| | - Timur M Mirzoev
- Myology Laboratory, Institute of Biomedical Problems RAS, 123007, 76A Khoroshevskoe shosse, Moscow, Russia.
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14
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Kotani T, Tamura Y, Kouzaki K, Kato H, Isemura M, Nakazato K. Percutaneous electrical stimulation-induced muscle contraction prevents the decrease in ribosome RNA and ribosome protein during pelvic hindlimb suspension. J Appl Physiol (1985) 2022; 133:822-833. [PMID: 36007895 DOI: 10.1152/japplphysiol.00204.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle unloading leads to muscle atrophy. Ribosome synthesis has been implicated as an important skeletal muscle mass regulator owing to its translational capacity. Muscle unloading induces a reduction in ribosome synthesis and content, with muscle atrophy. Percutaneous electrical muscle stimulation (pEMS)-induced muscle contraction is widely used in clinics to improve muscle mass. However, its efficacy in rescuing the reduction in ribosomal synthesis has not been addressed thus far. We examined the effects of daily pEMS treatment on ribosome synthesis and content during mouse hindlimb unloading. Male C57BL/6J mice were randomly assigned to sedentary (SED) and hindlimb unloading by pelvic suspension (HU) groups. Muscle contraction was triggered by pEMS treatment of the right gastrocnemius muscle of a subset of the HU group (HU+pEMS). Hindlimb unloading for 6 days significantly lowered 28S rRNA, rpL10, and rpS3 expression, which was rescued by daily pEMS treatment. The protein expression of phospho-p70S6K and UBF was significantly higher in the HU+pEMS than in the HU group. The mRNA expression of ribophagy receptor Nufip1 increased in both the HU and HU+pEMS groups. Protein light chain 3 (LC3)-II expression and the LC3-II/LC3-I ratio were increased by HU, but pEMS attenuated this increase. Our findings indicate that during HU, daily pEMS treatment prevents the reduction in the levels of some proteins associated with ribosome synthesis. Additionally, the HU-induced activation of ribosome degradation may be attenuated. These data provide insights into ribosome content regulation and the mechanism of attenuation of muscle atrophy by pEMS treatment during muscle disuse.
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Affiliation(s)
- Takaya Kotani
- Research Institute for Sport Science, Nippon Sport Science University, Tokyo, Japan
| | - Yuki Tamura
- Research Institute for Sport Science, Nippon Sport Science University, Tokyo, Japan.,Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan.,Faculty of Sport Science, Nippon Sport Science University, Tokyo, Japan
| | - Karina Kouzaki
- Research Institute for Sport Science, Nippon Sport Science University, Tokyo, Japan.,Graduate School of Medical and Health Science, Nippon Sport Science University, Tokyo, Japan
| | - Hikaru Kato
- Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Mako Isemura
- Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan
| | - Koichi Nakazato
- Research Institute for Sport Science, Nippon Sport Science University, Tokyo, Japan.,Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan.,Graduate School of Medical and Health Science, Nippon Sport Science University, Tokyo, Japan.,Faculty of Medical Science, Nippon Sport Science University, Tokyo, Japan
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15
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Hammarström D, Øfsteng SJ, Jacobsen NB, Flobergseter KB, Rønnestad BR, Ellefsen S. Ribosome accumulation during early phase resistance training in humans. Acta Physiol (Oxf) 2022; 235:e13806. [PMID: 35213791 PMCID: PMC9540306 DOI: 10.1111/apha.13806] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/04/2022] [Accepted: 02/21/2022] [Indexed: 12/16/2022]
Abstract
Aim To describe ribosome biogenesis during resistance training, its relation to training volume and muscle growth. Methods A training group (n = 11) performed 12 sessions (3‐4 sessions per week) of unilateral knee extension with constant and variable volume (6 and 3‐9 sets per session respectively) allocated to either leg. Ribosome abundance and biogenesis markers were assessed from vastus lateralis biopsies obtained at baseline, 48 hours after sessions 1, 4, 5, 8, 9 and 12, and after eight days of de‐training, and from a control group (n = 8). Muscle thickness was measured before and after the intervention. Results Training led to muscle growth (3.9% over baseline values, 95% CrI: [0.2, 7.5] vs. control) with concomitant increases in total RNA, ribosomal RNA, upstream binding factor (UBF) and ribosomal protein S6 with no differences between volume conditions. Total RNA increased rapidly in response to the first four sessions (8.6% [5.6, 11.7] per session), followed by a plateau and peak values after session 8 (49.5% [34.5, 66.5] above baseline). Total RNA abundance was associated with UBF protein levels (5.0% [0.2, 10.2] per unit UBF), and the rate of increase in total RNA levels predicted hypertrophy (0.3 mm [0.1, 0.4] per %‐point increase in total RNA per session). After de‐training, total RNA decreased (−19.3% [−29.0, −8.1]) without muscle mass changes indicating halted biosynthesis of ribosomes. Conclusion Ribosomes accumulate in the initial phase of resistance training with abundances sensitive to training cessation and associated with UBF protein levels. The average accumulation rate predicts muscle training‐induced hypertrophy.
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Affiliation(s)
- Daniel Hammarström
- Section for Health and Exercise Physiology Department of Public Health and Sport Sciences Inland Norway University of Applied Sciences Lillehammer Norway
- Swedish School of Sport and Health Sciences Stockholm Sweden
| | - Sjur J. Øfsteng
- Section for Health and Exercise Physiology Department of Public Health and Sport Sciences Inland Norway University of Applied Sciences Lillehammer Norway
| | - Nicolai B. Jacobsen
- Section for Health and Exercise Physiology Department of Public Health and Sport Sciences Inland Norway University of Applied Sciences Lillehammer Norway
| | - Krister B. Flobergseter
- Section for Health and Exercise Physiology Department of Public Health and Sport Sciences Inland Norway University of Applied Sciences Lillehammer Norway
| | - Bent R. Rønnestad
- Section for Health and Exercise Physiology Department of Public Health and Sport Sciences Inland Norway University of Applied Sciences Lillehammer Norway
| | - Stian Ellefsen
- Section for Health and Exercise Physiology Department of Public Health and Sport Sciences Inland Norway University of Applied Sciences Lillehammer Norway
- Innlandet Hospital Trust Lillehammer Norway
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16
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Gharahdaghi N, Rudrappa S, Brook MS, Farrash W, Idris I, Aziz MHA, Kadi F, Papaioannou K, Phillips BE, Sian T, Herrod PJ, Wilkinson DJ, Szewczyk NJ, Smith K, Atherton PJ. Pharmacological hypogonadism impairs molecular transducers of exercise-induced muscle growth in humans. J Cachexia Sarcopenia Muscle 2022; 13:1134-1150. [PMID: 35233984 PMCID: PMC8977972 DOI: 10.1002/jcsm.12843] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 08/25/2021] [Accepted: 09/30/2021] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND The relative role of skeletal muscle mechano-transduction in comparison with systemic hormones, such as testosterone (T), in regulating hypertrophic responses to exercise is contentious. We investigated the mechanistic effects of chemical endogenous T depletion adjuvant to 6 weeks of resistance exercise training (RET) on muscle mass, function, myogenic regulatory factors, and muscle anabolic signalling in younger men. METHODS Non-hypogonadal men (n = 16; 18-30 years) were randomized in a double-blinded fashion to receive placebo (P, saline n = 8) or the GnRH analogue, Goserelin [Zoladex (Z), 3.6 mg, n = 8], injections, before 6 weeks of supervised whole-body RET. Participants underwent dual-energy X-ray absorptiometry (DXA), ultrasound of m. vastus lateralis (VL), and VL biopsies for assessment of cumulative muscle protein synthesis (MPS), myogenic gene expression, and anabolic signalling pathway responses. RESULTS Zoladex suppressed endogenous T to within the hypogonadal range and was well tolerated; suppression was associated with blunted fat free mass [Z: 55.4 ± 2.8 to 55.8 ± 3.1 kg, P = 0.61 vs. P: 55.9 ± 1.7 to 57.4 ± 1.7 kg, P = 0.006, effect size (ES) = 0.31], composite strength (Z: 40 ± 2.3% vs. P: 49.8 ± 3.3%, P = 0.03, ES = 1.4), and muscle thickness (Z: 2.7 ± 0.4 to 2.69 ± 0.36 cm, P > 0.99 vs. P: 2.74 ± 0.32 to 2.91 ± 0.32 cm, P < 0.0001, ES = 0.48) gains. Hypogonadism attenuated molecular transducers of muscle growth related to T metabolism (e.g. androgen receptor: Z: 1.2 fold, P > 0.99 vs. P: 1.9 fold, P < 0.0001, ES = 0.85), anabolism/myogenesis (e.g. IGF-1Ea: Z: 1.9 fold, P = 0.5 vs. P: 3.3 fold, P = 0.0005, ES = 0.72; IGF-1Ec: Z: 2 fold, P > 0.99 vs. P: 4.7 fold, P = 0.0005, ES = 0.68; myogenin: Z: 1.3 fold, P > 0.99 vs. P: 2.7 fold, P = 0.002, ES = 0.72), RNA/DNA (Z: 0.47 ± 0.03 to 0.53 ± 0.03, P = 0.31 vs. P: 0.50 ± 0.01 to 0.64 ± 0.04, P = 0.003, ES = 0.72), and RNA/ASP (Z: 5.8 ± 0.4 to 6.8 ± 0.5, P > 0.99 vs. P: 6.5 ± 0.2 to 8.9 ± 1.1, P = 0.008, ES = 0.63) ratios, as well as acute RET-induced phosphorylation of growth signalling proteins (e.g. AKTser473 : Z: 2.74 ± 0.6, P = 0.2 vs. P: 5.5 ± 1.1 fold change, P < 0.001, ES = 0.54 and mTORC1ser2448 : Z: 1.9 ± 0.8, P > 0.99 vs. P: 3.6 ± 1 fold change, P = 0.002, ES = 0.53). Both MPS (Z: 1.45 ± 0.11 to 1.50 ± 0.06%·day-1 , P = 0.99 vs. P: 1.5 ± 0.12 to 2.0 ± 0.15%·day-1 , P = 0.01, ES = 0.97) and (extrapolated) muscle protein breakdown (Z: 93.16 ± 7.8 vs. P: 129.1 ± 13.8 g·day-1 , P = 0.04, ES = 0.92) were reduced with hypogonadism result in lower net protein turnover (3.9 ± 1.1 vs. 1.2 ± 1.1 g·day-1 , P = 0.04, ES = 0.95). CONCLUSIONS We conclude that endogenous T sufficiency has a central role in the up-regulation of molecular transducers of RET-induced muscle hypertrophy in humans that cannot be overcome by muscle mechano-transduction alone.
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Affiliation(s)
- Nima Gharahdaghi
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Supreeth Rudrappa
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Matthew S Brook
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Wesam Farrash
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK.,Laboratory Medicine Department, College of Applied Medical Sciences, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Iskandar Idris
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Muhammad Hariz Abdul Aziz
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Fawzi Kadi
- Division of Sports Sciences, School of Health and Medical Sciences, Örebro University, Örebro, Sweden
| | - Konstantinos Papaioannou
- Division of Sports Sciences, School of Health and Medical Sciences, Örebro University, Örebro, Sweden
| | - Bethan E Phillips
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Tanvir Sian
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Philip J Herrod
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Daniel J Wilkinson
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Nathaniel J Szewczyk
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Kenneth Smith
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
| | - Philip J Atherton
- MRC-Verus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR BRC, School of Medicine, University of Nottingham, Derby, UK
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17
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de Melo Madureira ÁN, de Oliveira JRS, de Menezes Lima VL. The Role of IL-6 Released During Exercise to Insulin Sensitivity and Muscle Hypertrophy. Mini Rev Med Chem 2022; 22:2419-2428. [PMID: 35264090 DOI: 10.2174/1389557522666220309161245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/25/2021] [Accepted: 01/27/2022] [Indexed: 11/22/2022]
Abstract
Interleukin-6 (IL-6) influences both inflammatory response and anti-inflammatory processes. This cytokine can be released by the exercising skeletal muscle, which characterizes it as a myokine. Unlike what is observed in inflammation, IL-6 produced by skeletal muscle is not preceded by the release of other pro-inflammatory cytokines, but is seems to be dependent on the lactate produced during exercise, thus causing different effects from those of seen in inflammatory state. After binding to its receptor, myokine IL-6 activates the PI3K-Akt pathway. One consequence of this upregulation is the potentiation of insulin signaling, which enhances insulin sensitivity. IL-6 increases GLUT-4 vesicle mobilization to muscle cell periphery, increasing the glucose transport into the cell, and also glycogen synthesis. Muscle glycogen provides energy for the ATP resynthesis, and regulates Ca2+ release by the sarcoplasmic reticulum, influencing muscle contraction, and, hence, muscle function by multiple pathways. Another implication for the upregulation of PI3K-Akt pathway is the activation of mTORC1, which regulates mRNA translational efficiency by regulating translation machinery, and translational capacity by inducing ribosomal biogenesis. Thus, IL-6 may contribute for skeletal muscle hypertrophy and function by increasing contractile protein synthesis.
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Affiliation(s)
- Álvaro Nóbrega de Melo Madureira
- Laboratory of Lipids and Application of Biomolecules to Prevalent and Neglected Diseases (LAB-DPN), Department of Biochemistry, Federal University of Pernambuco (UFPE)
| | - João Ricardhis Saturnino de Oliveira
- Laboratory of Lipids and Application of Biomolecules to Prevalent and Neglected Diseases (LAB-DPN), Department of Biochemistry, Federal University of Pernambuco (UFPE)
| | - Vera Lúcia de Menezes Lima
- Laboratory of Lipids and Application of Biomolecules to Prevalent and Neglected Diseases (LAB-DPN), Department of Biochemistry, Federal University of Pernambuco (UFPE)
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18
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Guo B, Bennet D, Belcher DJ, Kim HG, Nader GA. Chemotherapy agents reduce protein synthesis and ribosomal capacity in myotubes independent of oxidative stress. Am J Physiol Cell Physiol 2021; 321:C1000-C1009. [PMID: 34705587 DOI: 10.1152/ajpcell.00116.2021] [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: 11/22/2022]
Abstract
Chemotherapeutic agents (CAs) are first-line antineoplastic treatments against a wide variety of cancers. Despite their effectiveness in halting tumor progression, side effects associated with CAs promote muscle loss by incompletely understood mechanisms. To address this problem, we first identified how oxidative stress impairs protein synthesis in C2C12 myotubes. Transient elevations in reactive oxygen species (ROS) resulted in protein synthesis deficits and reduced ribosomal (r)RNA levels. Oxidative stress did not reduce rRNA gene (rDNA) transcription, but it caused an increase in rRNA and protein oxidation. To determine whether CAs affect protein synthesis independent of oxidative stress, we exposed myotubes to Paclitaxel (PTX), Doxorubicin (DXR), or Marizomib (Mzb) at doses that did result in elevated ROS levels (sub-ROS). Exposure to CAs reduced protein synthesis and rRNA levels, but unlike oxidative stress, sub-ROS exposures impaired rDNA transcription. These results indicate that although oxidative stress disrupts protein synthesis by compromising ribosomal quantity and quality, CAs at sub-ROS doses compromise protein synthesis and ribosomal capacity, at least in part, by reducing rDNA transcription. Therefore, CAs negatively impact protein synthesis by causing oxidative stress in addition to directly reducing the ribosomal capacity of myotubes in a ROS-independent manner.
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Affiliation(s)
- Bin Guo
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Devasier Bennet
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Daniel J Belcher
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania
| | - Hyo-Gun Kim
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Gustavo A Nader
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania.,Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania.,Penn State Cancer Institute, The Pennsylvania State University, University Park, Pennsylvania
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19
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Mesquita PHC, Vann CG, Phillips SM, McKendry J, Young KC, Kavazis AN, Roberts MD. Skeletal Muscle Ribosome and Mitochondrial Biogenesis in Response to Different Exercise Training Modalities. Front Physiol 2021; 12:725866. [PMID: 34646153 PMCID: PMC8504538 DOI: 10.3389/fphys.2021.725866] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/13/2021] [Indexed: 11/20/2022] Open
Abstract
Skeletal muscle adaptations to resistance and endurance training include increased ribosome and mitochondrial biogenesis, respectively. Such adaptations are believed to contribute to the notable increases in hypertrophy and aerobic capacity observed with each exercise mode. Data from multiple studies suggest the existence of a competition between ribosome and mitochondrial biogenesis, in which the first adaptation is prioritized with resistance training while the latter is prioritized with endurance training. In addition, reports have shown an interference effect when both exercise modes are performed concurrently. This prioritization/interference may be due to the interplay between the 5’ AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin complex 1 (mTORC1) signaling cascades and/or the high skeletal muscle energy requirements for the synthesis and maintenance of cellular organelles. Negative associations between ribosomal DNA and mitochondrial DNA copy number in human blood cells also provide evidence of potential competition in skeletal muscle. However, several lines of evidence suggest that ribosome and mitochondrial biogenesis can occur simultaneously in response to different types of exercise and that the AMPK-mTORC1 interaction is more complex than initially thought. The purpose of this review is to provide in-depth discussions of these topics. We discuss whether a curious competition between mitochondrial and ribosome biogenesis exists and show the available evidence both in favor and against it. Finally, we provide future research avenues in this area of exercise physiology.
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Affiliation(s)
| | | | - Stuart M Phillips
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | - James McKendry
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine, Auburn, AL, United States
| | | | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine, Auburn, AL, United States
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20
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Figueiredo VC, McCarthy JJ. Targeting cancer via ribosome biogenesis: the cachexia perspective. Cell Mol Life Sci 2021; 78:5775-5787. [PMID: 34196731 PMCID: PMC11072391 DOI: 10.1007/s00018-021-03888-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/03/2021] [Accepted: 06/18/2021] [Indexed: 12/14/2022]
Abstract
Cancer cachexia afflicts many advanced cancer patients with many progressing to death. While there have been many advancements in understanding the molecular mechanisms that contribute to the development of cancer cachexia, substantial gaps still exist. Chemotherapy drugs often target ribosome biogenesis to slow or blunt tumor cell growth and proliferation. Some of the most frequent side-effects of chemotherapy are loss of skeletal muscle mass, muscular strength and an increase in fatigue. Given that ribosome biogenesis has emerged as a main mechanism regulating muscle hypertrophy, and more recently, also implicated in muscle atrophy, we propose that some chemotherapy drugs can cause further muscle wasting via its effect on skeletal muscle cells. Many chemotherapy drugs, including the most prescribed drugs such as doxorubicin and cisplatin, affect ribosomal DNA transcription, or other pathways related to ribosome biogenesis. Furthermore, middle-aged and older individuals are the most affected population with cancer, and advanced cancer patients often show reduced levels of physical inactivity. Thus, aging and inactivity can themselves affect muscle ribosome biogenesis, which can further worsen the effect of chemotherapy on skeletal muscle ribosome biogenesis and, ultimately, muscle mass and function. We propose that chemotherapy can accelerate the onset or worsen cancer cachexia via its inhibitory effects on skeletal muscle ribosome biogenesis. We end our review by providing recommendations that could be used to ameliorate the negative effects of chemotherapy on skeletal muscle ribosome biogenesis.
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Affiliation(s)
- Vandré Casagrande Figueiredo
- College of Health Sciences, University of Kentucky, Lexington, KY, USA.
- Center for Muscle Biology, University of Kentucky, Lexington, KY, USA.
| | - John J McCarthy
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
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21
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Halle JL, Counts-Franch BR, Prince RM, Carson JA. The Effect of Mechanical Stretch on Myotube Growth Suppression by Colon-26 Tumor-Derived Factors. Front Cell Dev Biol 2021; 9:690452. [PMID: 34395422 PMCID: PMC8363303 DOI: 10.3389/fcell.2021.690452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 07/08/2021] [Indexed: 12/16/2022] Open
Abstract
Preclinical models and in vitro experiments have provided valuable insight into the regulation of cancer-induced muscle wasting. Colon-26 (C26) tumor cells induce cachexia in mice, and conditioned media (CM) from these cells promotes myotube atrophy and catabolic signaling. While mechanical stimuli can prevent some effects of tumor-derived factors on myotubes, the impact of mechanical signaling on tumor-derived factor regulation of myosin heavy chain (MyHC) expression is not well understood. Therefore, we examined the effects of stretch-induced mechanical signaling on C2C12 myotube growth and MyHC expression after C26 CM exposure. C26 CM was administered to myotubes on day 5 of differentiation for 48 h. During the last 4 or 24 h of C26 CM exposure, 5% static uniaxial stretch was administered. C26 CM suppressed myotube growth and MyHC protein and mRNA expression. Stretch for 24 h increased myotube size and prevented the C26 CM suppression of MyHC-Fast protein expression. Stretch did not change suppressed MyHC mRNA expression. Stretch for 24 h reduced Atrogin-1/MAFbx, MuRF-1, and LC3B II/I ratio and increased integrin β1D protein expression and the myogenin-to-MyoD protein ratio. Stretch in the last 4 h of CM increased ERK1/2 phosphorylation but did not alter the CM induction of STAT3 or p38 phosphorylation. These results provide evidence that in myotubes pre-incubated with CM, the induction of mechanical signaling can still provide a growth stimulus and preserve MyHC-Fast protein expression independent of changes in mRNA expression.
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Affiliation(s)
| | | | | | - James A. Carson
- Integrative Muscle Biology Laboratory, Division of Rehabilitation Sciences, College of Health Professions, University of Tennessee Health Science Center, Memphis, TN, United States
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22
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Kim HG, Huot JR, Pin F, Guo B, Bonetto A, Nader GA. Reduced rDNA transcription diminishes skeletal muscle ribosomal capacity and protein synthesis in cancer cachexia. FASEB J 2021; 35:e21335. [PMID: 33527503 PMCID: PMC7863588 DOI: 10.1096/fj.202002257r] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/07/2020] [Accepted: 12/16/2020] [Indexed: 12/18/2022]
Abstract
Muscle wasting in cancer is associated with deficits in protein synthesis, yet, the mechanisms underlying this anabolic impairment remain poorly understood. The capacity for protein synthesis is mainly determined by the abundance of muscle ribosomes, which is in turn regulated by transcription of the ribosomal (r)RNA genes (rDNA). In this study, we investigated whether muscle loss in a preclinical model of ovarian cancer is associated with a reduction in ribosomal capacity and was a consequence of impaired rDNA transcription. Tumor bearing resulted in a significant loss in gastrocnemius muscle weight and protein synthesis capacity, and was consistent with a significant reduction in rDNA transcription and ribosomal capacity. Despite the induction of the ribophagy receptor NUFIP1 mRNA and the loss of NUFIP1 protein, in vitro studies revealed that while inhibition of autophagy rescued NUFIP1, it did not prevent the loss of rRNA. Electrophoretic analysis of rRNA fragmentation from both in vivo and in vitro models showed no evidence of endonucleolytic cleavage, suggesting that rRNA degradation may not play a major role in modulating muscle ribosome abundance. Our results indicate that in this model of ovarian cancer-induced cachexia, the ability of skeletal muscle to synthesize protein is compromised by a reduction in rDNA transcription and consequently a lower ribosomal capacity. Thus, impaired ribosomal production appears to play a key role in the anabolic deficits associated with muscle wasting in cancer cachexia.
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Affiliation(s)
- Hyo-Gun Kim
- Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA
| | - Joshua R Huot
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Fabrizio Pin
- Department of Anatomy and Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Bin Guo
- Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA
| | - Andrea Bonetto
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Anatomy and Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA.,Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Gustavo A Nader
- Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA.,Penn State Cancer Institute, The Pennsylvania State University, University Park, PA, USA.,Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN, USA
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23
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Figueiredo VC, Wen Y, Alkner B, Fernandez-Gonzalo R, Norrbom J, Vechetti IJ, Valentino T, Mobley CB, Zentner GE, Peterson CA, McCarthy JJ, Murach KA, von Walden F. Genetic and epigenetic regulation of skeletal muscle ribosome biogenesis with exercise. J Physiol 2021; 599:3363-3384. [PMID: 33913170 DOI: 10.1113/jp281244] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/20/2021] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Ribosome biogenesis and MYC transcription are associated with acute resistance exercise (RE) and are distinct from endurance exercise in human skeletal muscle throughout a 24 h time course of recovery. A PCR-based method for relative ribosomal DNA (rDNA) copy number estimation was validated by whole genome sequencing and revealed that rDNA dosage is positively correlated with ribosome biogenesis in response to RE. Acute RE modifies rDNA methylation patterns in enhancer, intergenic spacer and non-canonical MYC-associated regions, but not the promoter. Myonuclear-specific rDNA methylation patterns with acute mechanical overload in mice corroborate and expand on rDNA findings with RE in humans. A genetic predisposition for hypertrophic responsiveness may exist based on rDNA gene dosage. ABSTRACT Ribosomes are the macromolecular engines of protein synthesis. Skeletal muscle ribosome biogenesis is stimulated by exercise, although the contribution of ribosomal DNA (rDNA) copy number and methylation to exercise-induced rDNA transcription is unclear. To investigate the genetic and epigenetic regulation of ribosome biogenesis with exercise, a time course of skeletal muscle biopsies was obtained from 30 participants (18 men and 12 women; 31 ± 8 years, 25 ± 4 kg m-2 ) at rest and 30 min, 3 h, 8 h and 24 h after acute endurance (n = 10, 45 min cycling, 70% V ̇ O 2 max ) or resistance exercise (n = 10, 4 × 7 × 2 exercises); 10 control participants underwent biopsies without exercise. rDNA transcription and dosage were assessed using quantitative PCR and whole genome sequencing. rDNA promoter methylation was investigated using massARRAY EpiTYPER and global rDNA CpG methylation was assessed using reduced-representation bisulphite sequencing. Ribosome biogenesis and MYC transcription were associated primarily with resistance but not endurance exercise, indicating preferential up-regulation during hypertrophic processes. With resistance exercise, ribosome biogenesis was associated with rDNA gene dosage, as well as epigenetic changes in enhancer and non-canonical MYC-associated areas in rDNA, but not the promoter. A mouse model of in vivo metabolic RNA labelling and genetic myonuclear fluorescence labelling validated the effects of an acute hypertrophic stimulus on ribosome biogenesis and Myc transcription, and also corroborated rDNA enhancer and Myc-associated methylation alterations specifically in myonuclei. The present study provides the first information on skeletal muscle genetic and rDNA gene-wide epigenetic regulation of ribosome biogenesis in response to exercise, revealing novel roles for rDNA dosage and CpG methylation.
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Affiliation(s)
- Vandré C Figueiredo
- Department of Physical Therapy, College of Health Sciences, University of Kentucky, Lexington, KY, USA.,The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
| | - Yuan Wen
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA.,Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Björn Alkner
- Department of Orthopaedics, Eksjö, Region Jönköping County and Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Rodrigo Fernandez-Gonzalo
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, and Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
| | - Jessica Norrbom
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Ivan J Vechetti
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA.,Department of Nutrition and Health Sciences, University of Nebraska, Lincoln, NE, USA
| | - Taylor Valentino
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA.,Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - C Brooks Mobley
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA.,Department of Physiology, University of Kentucky, Lexington, KY, USA
| | | | - Charlotte A Peterson
- Department of Physical Therapy, College of Health Sciences, University of Kentucky, Lexington, KY, USA.,The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA.,Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - John J McCarthy
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA.,Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Kevin A Murach
- Department of Physical Therapy, College of Health Sciences, University of Kentucky, Lexington, KY, USA.,The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
| | - Ferdinand von Walden
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA.,Department of Physiology, University of Kentucky, Lexington, KY, USA.,Division of Pediatric Neurology, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
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24
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Von Walden F, Rea M, Mobley CB, Fondufe-Mittendorf Y, McCarthy JJ, Peterson CA, Murach KA. The myonuclear DNA methylome in response to an acute hypertrophic stimulus. Epigenetics 2020; 15:1151-1162. [PMID: 32281477 PMCID: PMC7595631 DOI: 10.1080/15592294.2020.1755581] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In addition to multi-nucleated muscle fibres, numerous resident and infiltrating mononuclear cells populate the muscle compartment. As most epigenetic assays in skeletal muscle are conducted on whole tissue homogenates, essentially nothing is known about regulatory processes exclusively within muscle fibres in vivo. Utilizing a novel genetically modified mouse model developed by our laboratory, we (1) outline a simple and rapid workflow for isolating pure myonuclei from small tissue samples via fluorescent activated cell sorting and extracting high-quality large-fragment DNA for downstream analyses, and (2) provide information on myonuclear and interstitial cell nuclear CpG DNA methylation via reduced representation bisulphite sequencing (RRBS) using mice that were subjected to an acute mechanical overload of the plantaris muscle. In 3-month-old mice, myonuclei are ~50% of total nuclei in sham and ~30% in 3-d overloaded muscle, the difference being attributable to mononuclear cell infiltration and proliferation with overload. In purified myonuclei, pathway analysis of hypomethylated promoter regions following overload was distinct from interstitial nuclei and revealed marked regulation of factors that converge on the master regulator of muscle growth mTOR, and on autophagy. Specifically, acute hypomethylation of Rheb, Rictor, Hdac1, and Hdac2, in addition to a major driver of ribosome biogenesis Myc, reveals the epigenetic regulation of hypertrophic signalling within muscle fibres that may underpin the long-term growth response to loading. This study provides foundational information on global myonuclear epigenetics in vivo using RRBS, and demonstrates the importance of isolating specific nuclear populations to study the epigenetic regulation of skeletal muscle fibre adaptation.
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Affiliation(s)
- Ferdinand Von Walden
- K6 Department of Women’s and Children’s Health, Karolinska Institute, Stockholm, Sweden
- Department of Physiology, University of Kentucky, Lexington, KY, USA
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
| | - Matthew Rea
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - C. Brooks Mobley
- Department of Physiology, University of Kentucky, Lexington, KY, USA
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
| | | | - John J. McCarthy
- Department of Physiology, University of Kentucky, Lexington, KY, USA
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
| | - Charlotte A. Peterson
- Department of Physiology, University of Kentucky, Lexington, KY, USA
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
- Department of Physical Therapy, University of Kentucky, Lexington, KY, USA
| | - Kevin A. Murach
- The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
- Department of Physical Therapy, University of Kentucky, Lexington, KY, USA
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25
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Mirzoev TM. Skeletal Muscle Recovery from Disuse Atrophy: Protein Turnover Signaling and Strategies for Accelerating Muscle Regrowth. Int J Mol Sci 2020; 21:ijms21217940. [PMID: 33114683 PMCID: PMC7663166 DOI: 10.3390/ijms21217940] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/08/2020] [Accepted: 10/23/2020] [Indexed: 12/15/2022] Open
Abstract
Skeletal muscle fibers have a unique capacity to adjust their metabolism and phenotype in response to alternations in mechanical loading. Indeed, chronic mechanical loading leads to an increase in skeletal muscle mass, while prolonged mechanical unloading results in a significant decrease in muscle mass (muscle atrophy). The maintenance of skeletal muscle mass is dependent on the balance between rates of muscle protein synthesis and breakdown. While molecular mechanisms regulating protein synthesis during mechanical unloading have been relatively well studied, signaling events implicated in protein turnover during skeletal muscle recovery from unloading are poorly defined. A better understanding of the molecular events that underpin muscle mass recovery following disuse-induced atrophy is of significant importance for both clinical and space medicine. This review focuses on the molecular mechanisms that may be involved in the activation of protein synthesis and subsequent restoration of muscle mass after a period of mechanical unloading. In addition, the efficiency of strategies proposed to improve muscle protein gain during recovery is also discussed.
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Affiliation(s)
- Timur M Mirzoev
- Myology Laboratory, Institute of Biomedical Problems RAS, Moscow 123007, Russia
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26
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Vainshtein A, Sandri M. Signaling Pathways That Control Muscle Mass. Int J Mol Sci 2020; 21:ijms21134759. [PMID: 32635462 PMCID: PMC7369702 DOI: 10.3390/ijms21134759] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/23/2020] [Accepted: 07/01/2020] [Indexed: 12/12/2022] Open
Abstract
The loss of skeletal muscle mass under a wide range of acute and chronic maladies is associated with poor prognosis, reduced quality of life, and increased mortality. Decades of research indicate the importance of skeletal muscle for whole body metabolism, glucose homeostasis, as well as overall health and wellbeing. This tissue’s remarkable ability to rapidly and effectively adapt to changing environmental cues is a double-edged sword. Physiological adaptations that are beneficial throughout life become maladaptive during atrophic conditions. The atrophic program can be activated by mechanical, oxidative, and energetic distress, and is influenced by the availability of nutrients, growth factors, and cytokines. Largely governed by a transcription-dependent mechanism, this program impinges on multiple protein networks including various organelles as well as biosynthetic and quality control systems. Although modulating muscle function to prevent and treat disease is an enticing concept that has intrigued research teams for decades, a lack of thorough understanding of the molecular mechanisms and signaling pathways that control muscle mass, in addition to poor transferability of findings from rodents to humans, has obstructed efforts to develop effective treatments. Here, we review the progress made in unraveling the molecular mechanisms responsible for the regulation of muscle mass, as this continues to be an intensive area of research.
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Affiliation(s)
| | - Marco Sandri
- Veneto Institute of Molecular Medicine, via Orus 2, 35129 Padua, Italy
- Department of Biomedical Science, University of Padua, via G. Colombo 3, 35100 Padua, Italy
- Myology Center, University of Padua, via G. Colombo 3, 35100 Padova, Italy
- Department of Medicine, McGill University, Montreal, QC H3A 0G4, Canada
- Correspondence:
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27
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Lawrence MM, Van Pelt DW, Confides AL, Hunt ER, Hettinger ZR, Laurin JL, Reid JJ, Peelor FF, Butterfield TA, Dupont-Versteegden EE, Miller BF. Massage as a mechanotherapy promotes skeletal muscle protein and ribosomal turnover but does not mitigate muscle atrophy during disuse in adult rats. Acta Physiol (Oxf) 2020; 229:e13460. [PMID: 32125770 PMCID: PMC7293583 DOI: 10.1111/apha.13460] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 12/12/2022]
Abstract
AIM Interventions that decrease atrophy during disuse are desperately needed to maintain muscle mass. We recently found that massage as a mechanotherapy can improve muscle regrowth following disuse atrophy. Therefore, we aimed to determine if massage has similar anabolic effects when applied during normal weight bearing conditions (WB) or during atrophy induced by hindlimb suspension (HS) in adult rats. METHODS Adult (10 months) male Fischer344-Brown Norway rats underwent either hindlimb suspension (HS, n = 8) or normal WB (WB, n = 8) for 7 days. Massage was applied using cyclic compressive loading (CCL) in WB (WBM, n = 9) or HS rats (HSM, n = 9) and included four 30-minute bouts of CCL applied to gastrocnemius muscle every other day. RESULTS Massage had no effect on any anabolic parameter measured under WB conditions (WBM). In contrast, massage during HS (HSM) stimulated protein turnover, but did not mitigate muscle atrophy. Atrophy from HS was caused by both lowered protein synthesis and higher degradation. HS and HSM had lowered total RNA compared with WB and this was the result of significantly higher ribosome degradation in HS that was attenuated in HSM, without differences in ribosomal biogenesis. Also, massage increased protein turnover in the non-massaged contralateral limb during HS. Finally, we determined that total RNA degradation primarily dictates loss of muscle ribosomal content during disuse atrophy. CONCLUSION We conclude that massage is an effective mechanotherapy to impact protein turnover during muscle disuse in both the massaged and non-massaged contralateral muscle, but it does not attenuate the loss of muscle mass.
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Affiliation(s)
- Marcus M. Lawrence
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Douglas W. Van Pelt
- Department of Physical Therapy, University of Kentucky, Lexington, KY 40536, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA
| | - Amy L. Confides
- Department of Physical Therapy, University of Kentucky, Lexington, KY 40536, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA
| | - Emily R. Hunt
- Department of Physical Therapy, University of Kentucky, Lexington, KY 40536, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA
| | - Zachary R. Hettinger
- Department of Physical Therapy, University of Kentucky, Lexington, KY 40536, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA
| | - Jaime L. Laurin
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Justin J. Reid
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Frederick F. Peelor
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Timothy A. Butterfield
- Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington, KY 40536, USA
| | - Esther E. Dupont-Versteegden
- Department of Physical Therapy, University of Kentucky, Lexington, KY 40536, USA
- Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA
| | - Benjamin F. Miller
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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28
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Korponay TC, Balnis J, Vincent CE, Singer DV, Chopra A, Adam AP, Ginnan R, Singer HA, Jaitovich A. High CO 2 Downregulates Skeletal Muscle Protein Anabolism via AMP-activated Protein Kinase α2-mediated Depressed Ribosomal Biogenesis. Am J Respir Cell Mol Biol 2020; 62:74-86. [PMID: 31264907 DOI: 10.1165/rcmb.2019-0061oc] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
High CO2 retention, or hypercapnia, is associated with worse outcomes in patients with chronic pulmonary diseases. Skeletal muscle wasting is also an independent predictor of poor outcomes in patients with acute and chronic pulmonary diseases. Although previous evidence indicates that high CO2 accelerates skeletal muscle catabolism via AMPK (AMP-activated protein kinase)-FoxO3a-MuRF1 (E3-ubiquitin ligase muscle RING finger protein 1), little is known about the role of high CO2 in regulating skeletal muscle anabolism. In the present study, we investigated the potential role of high CO2 in attenuating skeletal muscle protein synthesis. We found that locomotor muscles from patients with chronic CO2 retention demonstrated depressed ribosomal gene expression in comparison with locomotor muscles from non-CO2-retaining individuals, and analysis of the muscle proteome of normo- and hypercapnic mice indicates reduction of important components of ribosomal structure and function. Indeed, mice chronically kept under a high-CO2 environment show evidence of skeletal muscle downregulation of ribosomal biogenesis and decreased protein synthesis as measured by the incorporation of puromycin into skeletal muscle. Hypercapnia did not regulate the mTOR pathway, and rapamycin-induced deactivation of mTOR did not cause a decrease in ribosomal gene expression. Loss-of-function studies in cultured myotubes showed that AMPKα2 regulates CO2-mediated reductions in ribosomal gene expression and protein synthesis. Although previous evidence has implicated TIF1A (transcription initiation factor-1α) and KDM2A (lysine-specific demethylase 2A) in AMPK-driven regulation of ribosomal gene expression, we found that these mediators were not required in the high CO2-induced depressed protein anabolism. Our research supports future studies targeting ribosomal biogenesis and protein synthesis to alleviate the effects of high CO2 on skeletal muscle turnover.
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Affiliation(s)
- Tanner C Korponay
- Division of Pulmonary and Critical Care Medicine.,Department of Molecular and Cellular Physiology, and
| | - Joseph Balnis
- Division of Pulmonary and Critical Care Medicine.,Department of Molecular and Cellular Physiology, and
| | | | | | - Amit Chopra
- Division of Pulmonary and Critical Care Medicine
| | - Alejandro P Adam
- Department of Molecular and Cellular Physiology, and.,Department of Ophthalmology, Albany Medical College, Albany, New York; and
| | - Roman Ginnan
- Department of Molecular and Cellular Physiology, and
| | | | - Ariel Jaitovich
- Division of Pulmonary and Critical Care Medicine.,Department of Molecular and Cellular Physiology, and
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29
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Hammarström D, Øfsteng S, Koll L, Hanestadhaugen M, Hollan I, Apró W, Whist JE, Blomstrand E, Rønnestad BR, Ellefsen S. Benefits of higher resistance-training volume are related to ribosome biogenesis. J Physiol 2020; 598:543-565. [PMID: 31813190 DOI: 10.1113/jp278455] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 12/03/2019] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS For individuals showing suboptimal adaptations to resistance training, manipulation of training volume is a potential measure to facilitate responses. This remains unexplored. Here, 34 untrained individuals performed contralateral resistance training with moderate and low volume for 12 weeks. Moderate volume led to larger increases in muscle cross-sectional area, strength and type II fibre-type transitions. These changes coincided with greater activation of signalling pathways controlling muscle growth and greater induction of ribosome synthesis. Out of 34 participants, thirteen displayed clear benefit of MOD on muscle hypertrophy and sixteen showed clear benefit of MOD on muscle strength gains. This coincided with greater total RNA accumulation in the early phase of the training period, suggesting that ribosomal biogenesis regulates the dose-response relationship between training volume and muscle hypertrophy. These results demonstrate that there is a dose-dependent relationship between training volume and outcomes. On the individual level, benefits of higher training volume were associated with increased ribosomal biogenesis. ABSTRACT Resistance-exercise volume is a determinant of training outcomes. However not all individuals respond in a dose-dependent fashion. In this study, 34 healthy individuals (males n = 16, 23.6 (4.1) years; females n = 18, 22.0 (1.3) years) performed moderate- (3 sets per exercise, MOD) and low-volume (1 set, LOW) resistance training in a contralateral fashion for 12 weeks (2-3 sessions per week). Muscle cross-sectional area (CSA) and strength were assessed at Weeks 0 and 12, along with biopsy sampling (m. vastus lateralis). Muscle biopsies were also sampled before and 1 h after the fifth session (Week 2). MOD resulted in larger increases in muscle CSA (5.2 (3.8)% versus 3.7 (3.7)%, P < 0.001) and strength (3.4-7.7% difference, all P < 0.05. This coincided with greater reductions in type IIX fibres from Week 0 to Week 12 (MOD, -4.6 percentage points; LOW -3.2 percentage points), greater phosphorylation of S6-kinase 1 (p85 S6K1Thr412 , 19%; p70 S6K1Thr389 , 58%) and ribosomal protein S6Ser235/236 (37%), greater rested-state total RNA (8.8%) and greater exercise-induced c-Myc mRNA expression (25%; Week 2, all P < 0.05). Thirteen and sixteen participants, respectively, displayed clear benefits in response to MOD on muscle hypertrophy and strength. Benefits were associated with greater accumulation of total RNA at Week 2 in the MOD leg, with every 1% difference increasing the odds of MOD benefit by 7.0% (P = 0.005) and 9.8% (P = 0.002). In conclusion, MOD led to greater functional and biological adaptations than LOW. Associations between dose-dependent total RNA accumulation and increases in muscle mass and strength point to ribosome biogenesis as a determinant of dose-dependent training responses.
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Affiliation(s)
- Daniel Hammarström
- Section for Health and Exercise Physiology, Department of Public Health and Sport Sciences, Inland Norway University of Applied Sciences, Elverum, Norway.,Swedish School of Sport and Health Sciences, Box 5626, SE-114 86, Stockholm, Sweden
| | - Sjur Øfsteng
- Section for Health and Exercise Physiology, Department of Public Health and Sport Sciences, Inland Norway University of Applied Sciences, Elverum, Norway
| | - Lise Koll
- Innlandet Hospital Trust, Postboks 990, 2629, Lillehammer, Norway
| | | | - Ivana Hollan
- Hospital for Rheumatic Diseases, Magrethe Grundtvigsvei 6, 2609, Lillehammer, Norway.,Brigham and Women's Hospital, 75 Francis Street, Boston, MA, 02115, USA
| | - William Apró
- Swedish School of Sport and Health Sciences, Box 5626, SE-114 86, Stockholm, Sweden
| | - Jon Elling Whist
- Innlandet Hospital Trust, Postboks 990, 2629, Lillehammer, Norway
| | - Eva Blomstrand
- Swedish School of Sport and Health Sciences, Box 5626, SE-114 86, Stockholm, Sweden
| | - Bent R Rønnestad
- Section for Health and Exercise Physiology, Department of Public Health and Sport Sciences, Inland Norway University of Applied Sciences, Elverum, Norway
| | - Stian Ellefsen
- Section for Health and Exercise Physiology, Department of Public Health and Sport Sciences, Inland Norway University of Applied Sciences, Elverum, Norway.,Innlandet Hospital Trust, Postboks 990, 2629, Lillehammer, Norway
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30
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von Walden F, Fernandez-Gonzalo R, Pingel J, McCarthy J, Stål P, Pontén E. Epigenetic Marks at the Ribosomal DNA Promoter in Skeletal Muscle Are Negatively Associated With Degree of Impairment in Cerebral Palsy. Front Pediatr 2020; 8:236. [PMID: 32582584 PMCID: PMC7283884 DOI: 10.3389/fped.2020.00236] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/20/2020] [Indexed: 12/12/2022] Open
Abstract
Introduction: Cerebral palsy (CP) is the most common motor impairment in children. Skeletal muscles in individuals with CP are typically weak, thin, and stiff. Whether epigenetic changes at the ribosomal DNA (rDNA) promoter are involved in this dysregulation remains unknown. Methods: Skeletal muscle samples were collected from 19 children with CP and 10 typically developed (TD) control children. Methylation of the rDNA promoter was analyzed using the Agena Epityper Mass array and gene expression by qRT-PCR. Results: Biceps brachii muscle ribosome biogenesis was suppressed in CP as compared to TD. Average methylation of the rDNA promoter was not different between CP and TD but negatively correlated to elbow flexor contracture in the CP group. Discussions: We observed a negative correlation between rDNA promoter methylation and degree of muscle contracture in the CP group. Children with CP with more severe motor impairment had less methylation of the rDNA promoter compared to less affected children. This finding suggests the importance of neural input and voluntary muscle movements for promoter methylation to occur in the biceps muscle.
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Affiliation(s)
- Ferdinand von Walden
- Division of Pediatric Neurology/Orthopedics/Rheumatology, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.,Department of Physiology, University of Kentucky, Lexington, KY, United States.,Center for Muscle Biology, University of Kentucky, Lexington, KY, United States
| | - Rodrigo Fernandez-Gonzalo
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, and Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
| | - Jessica Pingel
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - John McCarthy
- Department of Physiology, University of Kentucky, Lexington, KY, United States.,Center for Muscle Biology, University of Kentucky, Lexington, KY, United States
| | - Per Stål
- Laboratory of Muscle Biology, Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
| | - Eva Pontén
- Division of Pediatric Neurology/Orthopedics/Rheumatology, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
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31
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Kumar A, Davuluri G, Welch N, Kim A, Gangadhariah M, Allawy A, Priyadarshini A, McMullen MR, Sandlers Y, Willard B, Hoppel CL, Nagy LE, Dasarathy S. Oxidative stress mediates ethanol-induced skeletal muscle mitochondrial dysfunction and dysregulated protein synthesis and autophagy. Free Radic Biol Med 2019; 145:284-299. [PMID: 31574345 PMCID: PMC6910229 DOI: 10.1016/j.freeradbiomed.2019.09.031] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/25/2019] [Accepted: 09/25/2019] [Indexed: 12/21/2022]
Abstract
Protein synthesis and autophagy are regulated by cellular ATP content. We tested the hypothesis that mitochondrial dysfunction, including generation of reactive oxygen species (ROS), contributes to impaired protein synthesis and increased proteolysis resulting in tissue atrophy in a comprehensive array of models. In myotubes treated with ethanol, using unbiased approaches, we identified defects in mitochondrial electron transport chain components, endogenous antioxidants, and enzymes regulating the tricarboxylic acid (TCA) cycle. Using high sensitivity respirometry, we observed impaired cellular respiration, decreased function of complexes I, II, and IV, and a reduction in oxidative phosphorylation in ethanol-treated myotubes and muscle from ethanol-fed mice. These perturbations resulted in lower skeletal muscle ATP content and redox ratio (NAD+/NADH). Ethanol also caused a leak of electrons, primarily from complex III, with generation of mitochondrial ROS and reverse electron transport. Oxidant stress with lipid peroxidation (thiobarbituric acid reactive substances) and protein oxidation (carbonylated proteins) were increased in myotubes and skeletal muscle from mice and humans with alcoholic liver disease. Ethanol also impaired succinate oxidation in the TCA cycle with decreased metabolic intermediates. MitoTEMPO, a mitochondrial specific antioxidant, reversed ethanol-induced mitochondrial perturbations (including reduced oxygen consumption, generation of ROS and oxidative stress), increased TCA cycle intermediates, and reversed impaired protein synthesis and the sarcopenic phenotype. We show that ethanol causes skeletal muscle mitochondrial dysfunction, decreased protein synthesis, and increased autophagy, and that these perturbations are reversed by targeting mitochondrial ROS.
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Affiliation(s)
- Avinash Kumar
- The Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Gangarao Davuluri
- Integrated Physiology and Molecular Metabolism, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - Nicole Welch
- The Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; The Department of Gastroenterology and Hepatology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Adam Kim
- The Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Mahesha Gangadhariah
- The Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Allawy Allawy
- The Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Anupama Priyadarshini
- The Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Megan R McMullen
- The Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Yana Sandlers
- Department of Chemistry, Cleveland State University, Cleveland, OH, USA
| | - Belinda Willard
- The Department of Proteomics Research Core Services, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Charles L Hoppel
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Laura E Nagy
- The Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Srinivasan Dasarathy
- The Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; The Department of Gastroenterology and Hepatology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
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32
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Liu H, Yu H, Cao Z, Gu J, Pei L, Jia M, Su M. Kaempferol Modulates Autophagy and Alleviates Silica-Induced Pulmonary Fibrosis. DNA Cell Biol 2019; 38:1418-1426. [PMID: 31560574 DOI: 10.1089/dna.2019.4941] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Silicosis is an occupational disease characterized as inflammatory cells infiltration and severe progressive pulmonary fibrosis. Kaempferol (Kae), a flavonoid that exists in many plants and fruits, has been proved to have anti-inflammatory and antifibrosis functions. However, the effects of Kae on silicosis remain unclear. In the present study, we analyzed the therapeutic effects of Kae in 1-, 7-, and 28-day silicosis models, respectively. In the 1-day model, Kae treatment did not vary the wet-to-dry weight ratios of the lung, apoptotic rate, autophagy, or the expression of inflammatory factors. In contrast, Kae significantly inhibited pulmonary inflammation in the 7-day silicosis models and inhibited silica-induced pulmonary fibrosis in the 28-day models. Besides, we found that Kae partially restored silica-induced LC3 lipidation without increasing the p62 levels. Blocking autophagy with chloroquine antagonized the inhibitory effects of Kae on inflammation, suggesting that autophagy might be required in the therapeutic effects of Kae on silicosis. These findings indicated that Kae inhibits the progression of silica-induced pulmonary fibrosis, which may provide experimental evidences for Kae in the treatment of silicosis.
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Affiliation(s)
- Hangqi Liu
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China
| | - He Yu
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China
| | - Zhenju Cao
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China
| | - Junxu Gu
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China
| | - Lin Pei
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China
| | - Mei Jia
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China
| | - Ming Su
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, China
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Chaillou T. Ribosome specialization and its potential role in the control of protein translation and skeletal muscle size. J Appl Physiol (1985) 2019; 127:599-607. [DOI: 10.1152/japplphysiol.00946.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The ribosome is typically viewed as a supramolecular complex with constitutive and invariant capacity in mediating translation of mRNA into protein. This view has been challenged by recent research revealing that ribosome composition could be heterogeneous, and this heterogeneity leads to functional ribosome specialization. This review presents the idea that ribosome heterogeneity results from changes in its various components, including variations in ribosomal protein (RP) composition, posttranslational modifications of RPs, changes in ribosomal-associated proteins, alternative forms of rRNA, and posttranscriptional modifications of rRNAs. Ribosome heterogeneity could be orchestrated at several levels and may depend on numerous factors, such as the subcellular location, cell type, tissue specificity, the development state, cell state, ribosome biogenesis, RP turnover, physiological stimuli, and circadian rhythm. Ribosome specialization represents a completely new concept for the regulation of gene expression. Specialized ribosomes could modulate several aspects of translational control, such as mRNA translation selectivity, translation initiation, translational fidelity, and translation elongation. Recent research indicates that the expression of Rpl3 is markedly increased, while that of Rpl3l is highly reduced during mouse skeletal muscle hypertrophy. Moreover, Rpl3l overexpression impairs the growth and myogenic fusion of myotubes. Although the function of Rpl3 and Rpl3l in the ribosome remains to be clarified, these findings suggest that ribosome specialization may be potentially involved in the control of protein translation and skeletal muscle size. Limited data concerning ribosome specialization are currently available in skeletal muscle. Future investigations have the potential to delineate the function of specialized ribosomes in skeletal muscle.
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Affiliation(s)
- Thomas Chaillou
- School of Health Sciences, Örebro University, Örebro, Sweden
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34
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Hansson B, Olsen LA, Nicoll JX, von Walden F, Melin M, Strömberg A, Rullman E, Gustafsson T, Fry AC, Fernandez-Gonzalo R, Lundberg TR. Skeletal muscle signaling responses to resistance exercise of the elbow extensors are not compromised by a preceding bout of aerobic exercise. Am J Physiol Regul Integr Comp Physiol 2019; 317:R83-R92. [DOI: 10.1152/ajpregu.00022.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The current study examined the effects of a preceding bout of aerobic exercise (AE) on subsequent molecular signaling to resistance exercise (RE) of the elbow extensors. Eleven men performed unilateral elbow-extensor AE (~45 min at 70% peak workload) followed by unilateral RE (4 × 7 maximal repetitions) for both arms. Thus, one arm performed AE+RE interspersed with 15 min recovery, whereas the other arm conducted RE alone. Muscle biopsies were taken from the triceps brachii of each arm immediately before (PRE) and 15 min (POST1) and 3 h (POST2) after RE. Molecular markers involved in translation initiation, protein breakdown, mechanosignaling, and ribosome biogenesis were analyzed. Peak power during RE was reduced by 24% (±19%) when preceded by AE ( P < 0.05). Increases in PGC1a and MuRF1 expression were greater from PRE to POST2 in AE+RE compared with RE (18- vs. 3.5- and 4- vs. 2-fold, respectively, interaction, P < 0.05). Myostatin mRNA decreased in both arms ( P < 0.05). Phosphorylation of AMPK (Thr172) increased (2.5-fold), and 4E-BP1 (Thr37/46) decreased (2.0-fold), after AE (interactions, P < 0.05). p70 S6K, yes-associated protein, and c-Jun NH2-terminal kinase phosphorylation were unaltered, whereas focal adhesion kinase decreased ~1.5-fold, and β1-integrin increased ~1.3- to 1.5-fold, (time effect, P < 0.05). Abundance of 45S pre-ribosomal (r)RNA (internally transcribed spacer, ITS) decreased (~30%) after AE (interaction, P < 0.05), whereas CMYC mRNA was greater in AE+RE compared with RE (12-fold, P < 0.05). POLR1B abundance increased after both AE+RE and RE. All together, our results suggest that a single bout of AE leads to an immediate decrease in signaling for translation initiation and ribosome biogenesis. Yet, this did not translate into altered RE-induced signaling during the 3-h postexercise recovery period.
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Affiliation(s)
- Björn Hansson
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
| | - Luke A. Olsen
- Department of Biomedical Sciences, University of Kansas Medical Center, Kansas City, Kansas
| | - Justin X. Nicoll
- Department of Kinesiology, California State University, Northridge, California
| | - Ferdinand von Walden
- Department of Women’s and Children’s Health, Karolinska Institutet, Stockholm, Sweden
| | - Michael Melin
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
- Heart and Vascular Theme, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Anna Strömberg
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
| | - Eric Rullman
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
- Heart and Vascular Theme, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Thomas Gustafsson
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
| | - Andrew C. Fry
- Osness Human Performance Laboratories, University of Kansas, Lawrence, Kansas
| | - Rodrigo Fernandez-Gonzalo
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
| | - Tommy R. Lundberg
- Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
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35
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von Walden F. Ribosome biogenesis in skeletal muscle: coordination of transcription and translation. J Appl Physiol (1985) 2019; 127:591-598. [PMID: 31219775 DOI: 10.1152/japplphysiol.00963.2018] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Skeletal muscle mass responds in a remarkable manner to alterations in loading and use. It has long been clear that skeletal muscle hypertrophy can be prevented by inhibiting RNA synthesis. Since 80% of the cell's total RNA has been estimated to be rRNA, this finding indicates that de novo production of rRNA via transcription of the corresponding genes is important for such hypertrophy to occur. Transcription of rDNA by RNA Pol I is the rate-limiting step in ribosome biogenesis, indicating in turn that this biogenesis strongly influences the hypertrophic response. The present minireview focuses on 1) a brief description of the key steps in ribosome biogenesis and the relationship of this process to skeletal muscle mass and 2) the coordination of ribosome biogenesis and protein synthesis for growth or atrophy, as exemplified by the intracellular AMPK and mTOR pathways.
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Affiliation(s)
- Ferdinand von Walden
- Division of Pediatric Neurology, Department of Women's and Children's Health, Karolinska Institute, Stockholm, Sweden
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36
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Lautaoja JH, Lalowski M, Nissinen TA, Hentilä J, Shi Y, Ritvos O, Cheng S, Hulmi JJ. Muscle and serum metabolomes are dysregulated in colon-26 tumor-bearing mice despite amelioration of cachexia with activin receptor type 2B ligand blockade. Am J Physiol Endocrinol Metab 2019; 316:E852-E865. [PMID: 30860875 DOI: 10.1152/ajpendo.00526.2018] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cancer-associated cachexia reduces survival, which has been attenuated by blocking the activin receptor type 2B (ACVR2B) ligands in mice. The purpose of this study was to unravel the underlying physiology and novel cachexia biomarkers by use of the colon-26 (C26) carcinoma model of cancer cachexia. Male BALB/c mice were subcutaneously inoculated with C26 cancer cells or vehicle control. Tumor-bearing mice were treated with vehicle (C26+PBS) or soluble ACVR2B either before (C26+sACVR/b) or before and after (C26+sACVR/c) tumor formation. Skeletal muscle and serum metabolomics analysis was conducted by gas chromatography-mass spectrometry. Cancer altered various biologically functional groups representing 1) amino acids, 2) energy sources, and 3) nucleotide-related intermediates. Muscle metabolomics revealed increased content of free phenylalanine in cancer that strongly correlated with the loss of body mass within the last 2 days of the experiment. This correlation was also detected in serum. Decreased ribosomal RNA content and phosphorylation of a marker of pyrimidine synthesis revealed changes in nucleotide metabolism in cancer. Overall, the effect of the experimental C26 cancer predominated over blocking ACVR2B ligands in both muscle and serum. However, the level of methyl phosphate, which was decreased in muscle in cancer, was restored by sACVR2B-Fc treatment. In conclusion, experimental cancer affected muscle and blood metabolomes mostly independently of blocking ACVR2B ligands. Of the affected metabolites, we have identified free phenylalanine as a promising biomarker of muscle atrophy or cachexia. Finally, the decreased capacity for pyrimidine nucleotide and protein synthesis in tumor-bearing mice opens up new avenues in cachexia research.
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Affiliation(s)
- Juulia H Lautaoja
- Faculty of Sport and Health Sciences, Neuromuscular Research Center, University of Jyväskylä , Jyväskylä , Finland
| | - Maciej Lalowski
- Meilahti Clinical Proteomics Core Facility, HiLIFE, Faculty of Medicine, Biochemistry and Developmental Biology, University of Helsinki , Helsinki , Finland
| | - Tuuli A Nissinen
- Faculty of Sport and Health Sciences, Neuromuscular Research Center, University of Jyväskylä , Jyväskylä , Finland
| | - Jaakko Hentilä
- Faculty of Sport and Health Sciences, Neuromuscular Research Center, University of Jyväskylä , Jyväskylä , Finland
| | - Yi Shi
- The Key Laboratory of Systems Biomedicine, Ministry of Education, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Minhang District, Shanghai , China
| | - Olli Ritvos
- Department of Physiology, Faculty of Medicine, University of Helsinki , Helsinki , Finland
| | - Sulin Cheng
- The Key Laboratory of Systems Biomedicine, Ministry of Education, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Minhang District, Shanghai , China
- Exercise, Health and Technology Center, Department of Physical Education, and Exercise Translational Medicine Center, Shanghai Jiao Tong University, Minhang District, Shanghai , China
- Faculty of Sport and Health Sciences, University of Jyväskylä , Jyväskylä , Finland
| | - Juha J Hulmi
- Faculty of Sport and Health Sciences, Neuromuscular Research Center, University of Jyväskylä , Jyväskylä , Finland
- Department of Physiology, Faculty of Medicine, University of Helsinki , Helsinki , Finland
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37
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Kim HG, Guo B, Nader GA. Regulation of Ribosome Biogenesis During Skeletal Muscle Hypertrophy. Exerc Sport Sci Rev 2019; 47:91-97. [DOI: 10.1249/jes.0000000000000179] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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38
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Rantala R, Chaillou T. Mild hypothermia affects the morphology and impairs glutamine-induced anabolic response in human primary myotubes. Am J Physiol Cell Physiol 2019; 317:C101-C110. [PMID: 30917033 DOI: 10.1152/ajpcell.00008.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The specific impact of reduced temperature on skeletal muscle adaptation has been poorly investigated. Cold water immersion, one situation leading to decreased skeletal muscle temperature, is commonly proposed to reduce the perception of fatigue and muscle soreness after strenuous exercise. In contrast, it may impair long-term benefits of resistance exercise training on muscle strength and hypertrophy. To date, the physiological factors responsible for this blunted muscle adaptation remain unclear. Here, we used a cell culture model of human primary myotubes to specifically investigate the intrinsic behavior of muscle cells during mild hypothermia (MH). Newly formed myotubes were exposed to either 37°C or 32°C to evaluate the effect of MH on myotube size and morphology, protein synthesis, and anabolic signaling. We also compared the glutamine (GLUT)-induced hypertrophic response between myotubes incubated at 32°C or 37°C. We showed that 48 h exposure to MH altered the cellular morphology (greater myotube area, shorter myosegments, myotubes with irregular shape) and impaired GLUT-induced myotube hypertrophy. Moreover, MH specifically reduced protein synthesis at 8 h. This result may be explained by an altered regulation of ribosome biogenesis, as evidenced by a lower expression of 45S pre-ribosomal RNA and MYC protein, and a lower total RNA concentration. Furthermore, MH blunted GLUT-induced increase in protein synthesis at 8 h, a finding consistent with an impaired activation of the mechanistic target of rapamycin pathway. In conclusion, this study demonstrates that MH impairs the morphology of human myotubes and alters the hypertrophic response to GLUT.
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Affiliation(s)
- Robert Rantala
- Department of Health Sciences, Örebro University, Orebro, Sweden
| | - Thomas Chaillou
- Department of Health Sciences, Örebro University, Orebro, Sweden
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39
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Figueiredo VC, McCarthy JJ. Regulation of Ribosome Biogenesis in Skeletal Muscle Hypertrophy. Physiology (Bethesda) 2019; 34:30-42. [PMID: 30540235 PMCID: PMC6383632 DOI: 10.1152/physiol.00034.2018] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/11/2018] [Accepted: 09/13/2018] [Indexed: 01/22/2023] Open
Abstract
The ribosome is the enzymatic macromolecular machine responsible for protein synthesis. The rates of protein synthesis are primarily dependent on translational efficiency and capacity. Ribosome biogenesis has emerged as an important regulator of skeletal muscle growth and maintenance by altering the translational capacity of the cell. Here, we provide evidence to support a central role for ribosome biogenesis in skeletal muscle growth during postnatal development and in response to resistance exercise training. Furthermore, we discuss the cellular signaling pathways regulating ribosome biogenesis, discuss how myonuclear accretion affects translational capacity, and explore future areas of investigation within the field.
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Affiliation(s)
- Vandré Casagrande Figueiredo
- The Center for Muscle Biology, College of Health Sciences, University of Kentucky , Lexington, Kentucky
- Department of Rehabilitation Sciences, College of Medicine, University of Kentucky , Lexington, Kentucky
| | - John J McCarthy
- The Center for Muscle Biology, College of Health Sciences, University of Kentucky , Lexington, Kentucky
- Department of Physiology, University of Kentucky , Lexington, Kentucky
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40
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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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41
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Danzi MC, O'Neill N, Bixby JL, Lemmon VP. Can Chromatin Accessibility be Exploited for Axon Regeneration? Dev Neurobiol 2018; 78:991-997. [PMID: 29664188 DOI: 10.1002/dneu.22598] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 04/05/2018] [Indexed: 12/19/2022]
Abstract
Several studies have demonstrated that the intrinsic ability of neurons to regenerate their axons can be stimulated by maneuvers that favor the open state of chromatin, such as inhibiting histone deacetylase activity or increasing histone acetyltransferase activity. Taken together, these experiments suggest that axon regenerative ability can be increased by promoting chromatin accessibility. In this article, we assess the direct evidence in the literature for this hypothesis and re-examine other axon regeneration-promoting manipulations to see if they provide additional support. We find that several interventions known to enhance intrinsic axonal growth capability also increase chromatin accessibility. Although the support for this correlation is strong in the literature, we conclude with a word of caution about therapeutics attempting to exploit this relationship.
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Affiliation(s)
- Matt C Danzi
- Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida.,Center for Computational Science, University of Miami, Miami, Florida.,Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida
| | - Nick O'Neill
- Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida.,Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida
| | - John L Bixby
- Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida.,Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida.,Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida
| | - Vance P Lemmon
- Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida.,Center for Computational Science, University of Miami, Miami, Florida.,Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida
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42
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Emerging Role of mTOR Signaling-Related miRNAs in Cardiovascular Diseases. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:6141902. [PMID: 30305865 PMCID: PMC6165581 DOI: 10.1155/2018/6141902] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 07/04/2018] [Indexed: 12/21/2022]
Abstract
Mechanistic/mammalian target of rapamycin (mTOR), an atypical serine/threonine kinase of the phosphoinositide 3-kinase- (PI3K-) related kinase family, elicits a vital role in diverse cellular processes, including cellular growth, proliferation, survival, protein synthesis, autophagy, and metabolism. In the cardiovascular system, the mTOR signaling pathway integrates both intracellular and extracellular signals and serves as a central regulator of both physiological and pathological processes. MicroRNAs (miRs), a class of short noncoding RNA, are an emerging intricate posttranscriptional modulator of critical gene expression for the development and maintenance of homeostasis across a wide array of tissues, including the cardiovascular system. Over the last decade, numerous studies have revealed an interplay between miRNAs and the mTOR signaling circuit in the different cardiovascular pathophysiology, like myocardial infarction, hypertrophy, fibrosis, heart failure, arrhythmia, inflammation, and atherosclerosis. In this review, we provide a comprehensive state of the current knowledge regarding the mechanisms of interactions between the mTOR signaling pathway and miRs. We have also highlighted the latest advances on mTOR-targeted therapy in clinical trials and the new perspective therapeutic strategies with mTOR-targeting miRs in cardiovascular diseases.
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Bamman MM, Roberts BM, Adams GR. Molecular Regulation of Exercise-Induced Muscle Fiber Hypertrophy. Cold Spring Harb Perspect Med 2018; 8:cshperspect.a029751. [PMID: 28490543 DOI: 10.1101/cshperspect.a029751] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Skeletal muscle hypertrophy is a widely sought exercise adaptation to counteract the muscle atrophy of aging and disease, or to improve athletic performance. While this desired muscle enlargement is a well-known adaptation to resistance exercise training (RT), the mechanistic underpinnings are not fully understood. The purpose of this review is thus to provide the reader with a summary of recent advances in molecular mechanisms-based on the most current literature-that are thought to promote RT-induced muscle hypertrophy. We have therefore focused this discussion on the following areas of fertile investigation: ribosomal function and biogenesis, muscle stem (satellite) cell activity, transcriptional regulation, mechanotransduction, and myokine signaling.
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Affiliation(s)
- Marcas M Bamman
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294.,UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35205.,Geriatric Research, Education, and Clinical Center, Veterans' Affairs Medical Center, Birmingham, Alabama 35233
| | - Brandon M Roberts
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294.,UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35205
| | - Gregory R Adams
- Department of Physiology and Biophysics, University of California Irvine, Irvine, California 92617
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Von Walden F, Gantelius S, Liu C, Borgström H, Björk L, Gremark O, Stål P, Nader GA, PontéN E. Muscle contractures in patients with cerebral palsy and acquired brain injury are associated with extracellular matrix expansion, pro‐inflammatory gene expression, and reduced rRNA synthesis. Muscle Nerve 2018; 58:277-285. [DOI: 10.1002/mus.26130] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Ferdinand Von Walden
- Department of Women's and Children's health, Division of Neurology/Pediatric Orthopedics, Karolinska Institute, ALB Q2:07Karolinska University Hospital17176Stockholm Sweden
| | - Stefan Gantelius
- Department of Women's and Children's health, Division of Neurology/Pediatric Orthopedics, Karolinska Institute, ALB Q2:07Karolinska University Hospital17176Stockholm Sweden
- Department of Pediatric Orthopedic SurgeryKarolinska University HospitalStockholm Sweden
| | - Chang Liu
- Department of Women's and Children's health, Division of Neurology/Pediatric Orthopedics, Karolinska Institute, ALB Q2:07Karolinska University Hospital17176Stockholm Sweden
| | - Hanna Borgström
- Department of Women's and Children's health, Division of Neurology/Pediatric Orthopedics, Karolinska Institute, ALB Q2:07Karolinska University Hospital17176Stockholm Sweden
| | - Lars Björk
- Department of Women's and Children's health, Division of Neurology/Pediatric Orthopedics, Karolinska Institute, ALB Q2:07Karolinska University Hospital17176Stockholm Sweden
| | - Ola Gremark
- Department of Orthopedic SurgeryDanderyd HospitalStockholm Sweden
| | - Per Stål
- Department of Integrative Medical Biology, Laboratory of Muscle BiologyUmeå University Sweden
| | - Gustavo A. Nader
- Department. of Kinesiology and Huck Institute of the Life SciencesThe Pennsylvania State UniversityUniversity Park Pennsylvania USA
| | - Eva PontéN
- Department of Women's and Children's health, Division of Neurology/Pediatric Orthopedics, Karolinska Institute, ALB Q2:07Karolinska University Hospital17176Stockholm Sweden
- Department of Pediatric Orthopedic SurgeryKarolinska University HospitalStockholm Sweden
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Yamaga M, Takemoto M, Shoji M, Sakamoto K, Yamamoto M, Ishikawa T, Koshizaka M, Maezawa Y, Kobayashi K, Yokote K. Werner syndrome: a model for sarcopenia due to accelerated aging. Aging (Albany NY) 2018; 9:1738-1744. [PMID: 28738022 PMCID: PMC5559172 DOI: 10.18632/aging.101265] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 07/19/2017] [Indexed: 12/25/2022]
Abstract
Werner syndrome (WS) is a rare inheritable progeroid syndrome caused by a mutation in the WRN gene. Although WS has been described as a characteristic appearance of very slender extremities with a stocky trunk, few studies have investigated the loss of muscle mass, fat mass distribution (body composition), and mobility according to age and sex. Therefore, the aim of this study was to precisely describe the body composition in WS. Nine Japanese patients with WS (four males and five females; mean age 48±8.8 years) were recruited. Body composition was examined by dual-energy X-ray absorptiometry and computed tomography (CT). The hand grip strength and mobility were evaluated using the two-step test, stand-up test and 25-question geriatric locomotive function scale (GLFS). The mean skeletal muscle index (SMI) was 4.0±0.6 kg/m2. SMI of all patients met the criteria of sarcopenia, even though some patients were aged < 40 years. All patients also showed deceased mobility. In conclusion, these results indicate that all patients with WS, even those aged < 40 years, had already lost muscle mass to the level of sarcopenia. Continued research on sarcopenia in WS might facilitate the discovery of novel mechanisms and development of new treatment strategies for sarcopenia.
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Affiliation(s)
- Masaya Yamaga
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,Department of Medicine, Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba, 260-8670, Japan
| | - Minoru Takemoto
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,School of Medicine, International University of Health and Welfare, Department of Diabetes, Metabolism and Endocrinology, Chiba, 286-8686, Japan
| | - Mayumi Shoji
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,Department of Medicine, Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba, 260-8670, Japan
| | - Kenichi Sakamoto
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,Eastern Chiba Medical Center, Chiba, 283-8686, Japan
| | - Masashi Yamamoto
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,Department of Medicine, Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba, 260-8670, Japan
| | - Takahiro Ishikawa
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,Department of Medicine, Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba, 260-8670, Japan
| | - Masaya Koshizaka
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,Department of Medicine, Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba, 260-8670, Japan
| | - Yoshiro Maezawa
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,Department of Medicine, Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba, 260-8670, Japan
| | - Kazuki Kobayashi
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,Asahi General Hospital, 1326 I, Chiba, 289-2511, Japan
| | - Koutaro Yokote
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, 260-8670, Japan.,Department of Medicine, Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba, 260-8670, Japan
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46
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Hulmi JJ, Nissinen TA, Räsänen M, Degerman J, Lautaoja JH, Hemanthakumar KA, Backman JT, Ritvos O, Silvennoinen M, Kivelä R. Prevention of chemotherapy-induced cachexia by ACVR2B ligand blocking has different effects on heart and skeletal muscle. J Cachexia Sarcopenia Muscle 2018; 9:417-432. [PMID: 29230965 PMCID: PMC5879968 DOI: 10.1002/jcsm.12265] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/15/2017] [Accepted: 10/12/2017] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Toxicity of chemotherapy on skeletal muscles and the heart may significantly contribute to cancer cachexia, mortality, and decreased quality of life. Doxorubicin (DOX) is an effective cytostatic agent, which unfortunately has toxic effects on many healthy tissues. Blocking of activin receptor type IIB (ACVR2B) ligands is an often used strategy to prevent skeletal muscle loss, but its effects on the heart are relatively unknown. METHODS The effects of DOX treatment with or without pre-treatment with soluble ACVR2B-Fc (sACVR2B-Fc) were investigated. The mice were randomly assigned into one of the three groups: (1) vehicle (PBS)-treated controls, (2) DOX-treated mice (DOX), and (3) DOX-treated mice administered with sACVR2B-Fc during the experiment (DOX + sACVR2B-Fc). DOX was administered with a cumulative dose of 24 mg/kg during 2 weeks to investigate cachexia outcome in the heart and skeletal muscle. To understand similarities and differences between skeletal and cardiac muscles in their responses to chemotherapy, the tissues were collected 20 h after a single DOX (15 mg/kg) injection and analysed with genome-wide transcriptomics and mRNA and protein analyses. The combination group was pre-treated with sACVR2B-Fc 48 h before DOX administration. Major findings were also studied in mice receiving only sACVR2B-Fc. RESULTS The DOX treatment induced similar (~10%) wasting in skeletal muscle and the heart. However, transcriptional changes in response to DOX were much greater in skeletal muscle. Pathway analysis and unbiased transcription factor analysis showed that p53-p21-REDD1 is the main common pathway activated by DOX in both skeletal and cardiac muscles. These changes were attenuated by blocking ACVR2B ligands especially in skeletal muscle. Tceal7 (3-fold to 5-fold increase), transferrin receptor (1.5-fold increase), and Ccl21 (0.6-fold to 0.9-fold decrease) were identified as novel genes responsive to blocking ACVR2B ligands. Overall, at the transcriptome level, ACVR2B ligand blocking had only minor influence in the heart while it had marked effects in skeletal muscle. The same was also true for the effects on tissue wasting. This may be explained in part by about 18-fold higher gene expression of myostatin in skeletal muscle compared with the heart. CONCLUSIONS Cardiac and skeletal muscles display similar atrophy after DOX treatment, but the mechanisms for this may differ between the tissues. The present results suggest that p53-p21-REDD1 signalling is the main common DOX-activated pathway in these tissues and that blocking activin receptor ligands attenuates this response, especially in skeletal muscle supporting the overall stronger effects of this treatment in skeletal muscles.
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Affiliation(s)
- Juha J Hulmi
- Biology of Physical Activity, Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.,Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Tuuli A Nissinen
- Biology of Physical Activity, Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Markus Räsänen
- Wihuri Research Institute, Helsinki, Finland and Translational Cancer Biology Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Joni Degerman
- Wihuri Research Institute, Helsinki, Finland and Translational Cancer Biology Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Juulia H Lautaoja
- Biology of Physical Activity, Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Karthik Amudhala Hemanthakumar
- Wihuri Research Institute, Helsinki, Finland and Translational Cancer Biology Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Janne T Backman
- Department of Clinical Pharmacology, Faculty of Medicine, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Olli Ritvos
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Mika Silvennoinen
- Biology of Physical Activity, Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Riikka Kivelä
- Wihuri Research Institute, Helsinki, Finland and Translational Cancer Biology Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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Connolly M, Paul R, Farre-Garros R, Natanek SA, Bloch S, Lee J, Lorenzo JP, Patel H, Cooper C, Sayer AA, Wort SJ, Griffiths M, Polkey MI, Kemp PR. miR-424-5p reduces ribosomal RNA and protein synthesis in muscle wasting. J Cachexia Sarcopenia Muscle 2018; 9:400-416. [PMID: 29215200 PMCID: PMC5879973 DOI: 10.1002/jcsm.12266] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/27/2017] [Accepted: 10/12/2017] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND A loss of muscle mass occurs as a consequence of a range of chronic and acute diseases as well as in older age. This wasting results from an imbalance of protein synthesis and degradation with a reduction in synthesis and resistance to anabolic stimulation often reported features. Ribosomes are required for protein synthesis, so changes in the control of ribosome synthesis are potential contributors to muscle wasting. MicroRNAs (miRNAs) are known regulators of muscle phenotype and have been shown to modulate components of the protein synthetic pathway. One miRNA that is predicted to target a number of components of protein synthetic pathway is miR-424-5p, which is elevated in the quadriceps of patients with chronic obstructive pulmonary disease (COPD). METHODS Targets of miR-424-5p were identified by Argonaute2 pull down, and the effects of the miRNA on RNA and protein expression were determined by quantitative polymerase chain reaction and western blotting in muscle cells in vitro. Protein synthesis was determined by puromycin incorporation in vitro. The miRNA was over-expressed in the tibialis anterior muscle of mice by electroporation and the effects quantified. Finally, quadriceps expression of the miRNA was determined by quantitative polymerase chain reaction in patients with COPD and intensive care unit (ICU)-acquired weakness and in patients undergoing aortic surgery as well as in individuals from the Hertfordshire Sarcopenia Study. RESULTS Pull-down assays showed that miR-424-5p bound to messenger RNAs encoding proteins associated with muscle protein synthesis. The most highly enriched messenger RNAs encoded proteins required for the Pol I RNA pre-initiation complex required for ribosomal RNA (rRNA) transcription, (PolR1A and upstream binding transcription factor). In vitro, miR-424-5p reduced the expression of these RNAs, reduced rRNA levels, and inhibited protein synthesis. In mice, over-expression of miR-322 (rodent miR-424 orthologue) caused fibre atrophy and reduced upstream binding transcription factor expression and rRNA levels. In humans, elevated miR-424-5p associated with markers of disease severity in COPD (FEV1 %), in patients undergoing aortic surgery (LVEF%), and in patients with ICU-acquired weakness (days in ICU). In patients undergoing aortic surgery, preoperative miR-424-5p expression in skeletal muscle was associated with muscle loss over the following 7 days. CONCLUSIONS These data suggest that miR-424-5p regulates rRNA synthesis by inhibiting Pol I pre-initiation complex formation. Increased miR-424-5p expression in patients with conditions associated with muscle wasting is likely to contribute to the inhibition of protein synthesis and loss of muscle mass.
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Affiliation(s)
- Martin Connolly
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Richard Paul
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.,National Institute for Health Research Respiratory Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, SW3 6NP, UK
| | - Roser Farre-Garros
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Samantha A Natanek
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Susannah Bloch
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Jen Lee
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Jose P Lorenzo
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Harnish Patel
- MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.,NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Cyrus Cooper
- MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK
| | - Avan A Sayer
- MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.,AGE Research Group, Institute of Neuroscience and Institute for Ageing, Newcastle University, Newcastle upon Tyne, UK.,NIHR Newcastle Biomedical Research Centre, Newcastle University and Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Stephen J Wort
- National Institute for Health Research Respiratory Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, SW3 6NP, UK
| | - Mark Griffiths
- Inflammation, Repair and Development, National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Michael I Polkey
- National Institute for Health Research Respiratory Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, SW3 6NP, UK
| | - Paul R Kemp
- Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
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48
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Giguère V. Canonical signaling and nuclear activity of mTOR-a teamwork effort to regulate metabolism and cell growth. FEBS J 2018; 285:1572-1588. [PMID: 29337437 DOI: 10.1111/febs.14384] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 12/21/2017] [Accepted: 01/10/2018] [Indexed: 01/07/2023]
Abstract
Mechanistic (or mammalian) target of rapamycin (mTOR) is a kinase that regulates almost all functions related to cell growth and metabolism in response to extra- and intracellular stimuli, such as availability of nutrients, the presence of growth factors, or the energy status of the cell. As part of two distinct protein complexes, mTORC1 and mTORC2, the kinase has been shown to influence cell growth and proliferation by controlling ribosome biogenesis, mRNA translation, carbohydrate and lipid metabolism, protein degradation, autophagy as well as microtubule and actin dynamics. In addition to these well-characterized functions, mTOR can also influence gene transcription. While most studies focused on investigating how canonical mTOR signaling regulates the activity of transcription factors outside the nucleus, recent findings point to a more direct role for mTOR as a transcription factor operating on chromatin in the nucleus. In particular, recent genome-wide identification of mTOR targets on chromatin reveals that its activities in the nucleus and cytoplasm are functionally and biologically linked, thus uncovering a novel paradigm in mTOR function.
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Affiliation(s)
- Vincent Giguère
- Departments of Biochemistry, Medicine and Oncology, Faculty of Medicine, Goodman Cancer Research Centre, McGill University, Montréal, Canada
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49
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Figueiredo VC, Zeng N, D'Souza RF, Markworth JF, Della Gatta PA, Petersen A, Barnett MPG, Cameron-Smith D. High dose of whey protein after resistance exercise promotes 45 S preribosomal RNA synthesis in older men. Nutrition 2017; 50:105-107. [PMID: 29433916 DOI: 10.1016/j.nut.2017.11.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 11/26/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Vandré C Figueiredo
- The Liggins Institute, The University of Auckland, Private Bag 92 019, Victoria Street West, Auckland 1142, New Zealand
| | - Nina Zeng
- The Liggins Institute, The University of Auckland, Private Bag 92 019, Victoria Street West, Auckland 1142, New Zealand
| | - Randall F D'Souza
- The Liggins Institute, The University of Auckland, Private Bag 92 019, Victoria Street West, Auckland 1142, New Zealand
| | - James F Markworth
- The Liggins Institute, The University of Auckland, Private Bag 92 019, Victoria Street West, Auckland 1142, New Zealand
| | - Paul A Della Gatta
- Institute for Physical Activity and Nutrition (IPAN), Deakin University, Geelong, Australia
| | - Aaron Petersen
- Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Australia
| | - Matthew P G Barnett
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - David Cameron-Smith
- The Liggins Institute, The University of Auckland, Private Bag 92 019, Victoria Street West, Auckland 1142, New Zealand; Food & Bio-based Products Group, AgResearch, Palmerston North, 4474, New Zealand; Riddet Institute, Palmerston North, 4442, New Zealand
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50
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He J, Yang Y, Zhang J, Chen J, Wei X, He J, Luo L. Ribosome biogenesis protein Urb1 acts downstream of mTOR complex 1 to modulate digestive organ development in zebrafish. J Genet Genomics 2017; 44:567-576. [DOI: 10.1016/j.jgg.2017.09.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 09/27/2017] [Accepted: 09/28/2017] [Indexed: 12/23/2022]
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