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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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52
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Mobley CB, Haun CT, Roberson PA, Mumford PW, Kephart WC, Romero MA, Osburn SC, Vann CG, Young KC, Beck DT, Martin JS, Lockwood CM, Roberts MD. Biomarkers associated with low, moderate, and high vastus lateralis muscle hypertrophy following 12 weeks of resistance training. PLoS One 2018; 13:e0195203. [PMID: 29621305 PMCID: PMC5886420 DOI: 10.1371/journal.pone.0195203] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/19/2018] [Indexed: 12/20/2022] Open
Abstract
We sought to identify biomarkers which delineated individual hypertrophic responses to resistance training. Untrained, college-aged males engaged in full-body resistance training (3 d/wk) for 12 weeks. Body composition via dual x-ray absorptiometry (DXA), vastus lateralis (VL) thickness via ultrasound, blood, VL muscle biopsies, and three-repetition maximum (3-RM) squat strength were obtained prior to (PRE) and following (POST) 12 weeks of training. K-means cluster analysis based on VL thickness changes identified LOW [n = 17; change (mean±SD) = +0.11±0.14 cm], modest (MOD; n = 29, +0.40±0.06 cm), and high (HI; n = 21, +0.69±0.14 cm) responders. Biomarkers related to histology, ribosome biogenesis, proteolysis, inflammation, and androgen signaling were analyzed between clusters. There were main effects of time (POST>PRE, p<0.05) but no cluster×time interactions for increases in DXA lean body mass, type I and II muscle fiber cross sectional area and myonuclear number, satellite cell number, and macronutrients consumed. Interestingly, PRE VL thickness was ~12% greater in LOW versus HI (p = 0.021), despite POST values being ~12% greater in HI versus LOW (p = 0.006). However there was only a weak correlation between PRE VL thickness scores and change in VL thickness (r2 = 0.114, p = 0.005). Forced post hoc analysis indicated that muscle total RNA levels (i.e., ribosome density) did not significantly increase in the LOW cluster (351±70 ng/mg to 380±62, p = 0.253), but increased in the MOD (369±115 to 429±92, p = 0.009) and HI clusters (356±77 to 470±134, p<0.001; POST HI>POST LOW, p = 0.013). Nonetheless, there was only a weak association between change in muscle total RNA and VL thickness (r2 = 0.079, p = 0.026). IL-1β mRNA levels decreased in the MOD and HI clusters following training (p<0.05), although associations between this marker and VL thickness changes were not significant (r2 = 0.0002, p = 0.919). In conclusion, individuals with lower pre-training VL thickness values and greater increases muscle total RNA levels following 12 weeks of resistance training experienced greater VL muscle growth, although these biomarkers individually explained only ~8–11% of the variance in hypertrophy.
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Affiliation(s)
| | - Cody T. Haun
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Paul A. Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Petey W. Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Wesley C. Kephart
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Matthew A. Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Shelby C. Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Christopher G. Vann
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Kaelin C. Young
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine–Auburn Campus, Auburn, AL, United States of America
| | - Darren T. Beck
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine–Auburn Campus, Auburn, AL, United States of America
| | - Jeffrey S. Martin
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine–Auburn Campus, Auburn, AL, United States of America
| | | | - Michael D. Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine–Auburn Campus, Auburn, AL, United States of America
- * E-mail:
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53
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Bennett AH, O’Donohue MF, Gundry SR, Chan AT, Widrick J, Draper I, Chakraborty A, Zhou Y, Zon LI, Gleizes PE, Beggs AH, Gupta VA. RNA helicase, DDX27 regulates skeletal muscle growth and regeneration by modulation of translational processes. PLoS Genet 2018. [PMID: 29518074 PMCID: PMC5843160 DOI: 10.1371/journal.pgen.1007226] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Gene expression in a tissue-specific context depends on the combined efforts of epigenetic, transcriptional and post-transcriptional processes that lead to the production of specific proteins that are important determinants of cellular identity. Ribosomes are a central component of the protein biosynthesis machinery in cells; however, their regulatory roles in the translational control of gene expression in skeletal muscle remain to be defined. In a genetic screen to identify critical regulators of myogenesis, we identified a DEAD-Box RNA helicase, DDX27, that is required for skeletal muscle growth and regeneration. We demonstrate that DDX27 regulates ribosomal RNA (rRNA) maturation, and thereby the ribosome biogenesis and the translation of specific transcripts during myogenesis. These findings provide insight into the translational regulation of gene expression in myogenesis and suggest novel functions for ribosomes in regulating gene expression in skeletal muscles.
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Affiliation(s)
- Alexis H. Bennett
- Division of Genetics, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marie-Francoise O’Donohue
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, UPS, CNRS, France
| | - Stacey R. Gundry
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Aye T. Chan
- Stem Cell Program and Pediatric Hematology/Oncology, Boston Children's Hospital and Dana Farber Cancer Institute, Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jeffrey Widrick
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Isabelle Draper
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts, United States of America
| | - Anirban Chakraborty
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, UPS, CNRS, France
- Division of Molecular Genetics and Cancer, NU Centre for Science Education and Research, Nitte University, Mangalore, India
| | - Yi Zhou
- Stem Cell Program and Pediatric Hematology/Oncology, Boston Children's Hospital and Dana Farber Cancer Institute, Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Leonard I. Zon
- Stem Cell Program and Pediatric Hematology/Oncology, Boston Children's Hospital and Dana Farber Cancer Institute, Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Howard Hughes Medical Institute, Boston, Massachusetts, United States of America
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, UPS, CNRS, France
| | - Alan H. Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Vandana A. Gupta
- Division of Genetics, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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54
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Crossland H, Timmons JA, Atherton PJ. A dynamic ribosomal biogenesis response is not required for IGF-1-mediated hypertrophy of human primary myotubes. FASEB J 2017; 31:5196-5207. [PMID: 28774889 PMCID: PMC5690393 DOI: 10.1096/fj.201700329r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/17/2017] [Indexed: 12/11/2022]
Abstract
Increased ribosomal DNA transcription has been proposed to limit muscle protein synthesis, making ribosome biogenesis central to skeletal muscle hypertrophy. We examined the relationship between ribosomal RNA (rRNA) production and IGF-1-mediated myotube hypertrophy in vitro Primary skeletal myotubes were treated with IGF-1 (50 ng/ml) with or without 0.5 µM CX-5461 (CX), an inhibitor of RNA polymerase I. Myotube diameter, total protein, and RNA and DNA levels were measured along with markers of RNA polymerase I regulatory factors and regulators of protein synthesis. CX treatment reduced 45S pre-rRNA expression (-64 ± 5% vs. IGF-1; P < 0.001) and total RNA content (-16 ± 2% vs. IGF-1; P < 0.001) in IGF-1-treated myotubes. IGF-1-mediated increases in myotube diameter (1.27 ± 0.09-fold, P < 0.05 vs. control) and total protein (+20 ± 2%; P < 0.001 vs. control) were not prevented by CX treatment. Suppression of rRNA synthesis during IGF-1 treatment did not prevent early increases in AKT (+203 ± 39% vs. CX; P < 0.001) and p70 S6K1 (269 ± 41% vs. CX; P < 0.001) phosphorylation. Despite robust inhibition of the dynamic ribosomal biogenesis response to IGF-1, myotube diameter and protein accretion were sustained. Thus, while ribosome biogenesis represents a potential site for the regulation of skeletal muscle protein synthesis and muscle mass, it does not appear to be a prerequisite for IGF-1-induced myotube hypertrophy in vitro.-Crossland, H., Timmons, J. A., Atherton, P. J. A dynamic ribosomal biogenesis response is not required for IGF-1-mediated hypertrophy of human primary myotubes.
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Affiliation(s)
- Hannah Crossland
- Division of Genetics and Molecular Medicine, Guy's Hospital, King's College London, London, United Kingdom; and
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, United Kingdom
| | - James A Timmons
- Division of Genetics and Molecular Medicine, Guy's Hospital, King's College London, London, United Kingdom; and
| | - Philip J Atherton
- School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, United Kingdom
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55
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Mobley CB, Mumford PW, Kephart WC, Haun CT, Holland AM, Beck DT, Martin JS, Young KC, Anderson RG, Patel RK, Langston GL, Lowery RP, Wilson JM, Roberts MD. Aging in Rats Differentially Affects Markers of Transcriptional and Translational Capacity in Soleus and Plantaris Muscle. Front Physiol 2017; 8:518. [PMID: 28775694 PMCID: PMC5517446 DOI: 10.3389/fphys.2017.00518] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 07/06/2017] [Indexed: 11/13/2022] Open
Abstract
Alterations in transcriptional and translational mechanisms occur during skeletal muscle aging and such changes may contribute to age-related atrophy. Herein, we examined markers related to global transcriptional output (i.e., myonuclear number, total mRNA and RNA pol II levels), translational efficiency [i.e., eukaryotic initiation and elongation factor levels and muscle protein synthesis (MPS) levels] and translational capacity (ribosome density) in the slow-twitch soleus and fast-twitch plantaris muscles of male Fischer 344 rats aged 3, 6, 12, 18, and 24 months (n = 9-10 per group). We also examined alterations in markers of proteolysis and oxidative stress in these muscles (i.e., 20S proteasome activity, poly-ubiquinated protein levels and 4-HNE levels). Notable plantaris muscle observations included: (a) fiber cross sectional area (CSA) was 59% (p < 0.05) and 48% (p < 0.05) greater in 12 month vs. 3 month and 24 month rats, respectively, suggesting a peak lifetime value near 12 months and age-related atrophy by 24 months, (b) MPS levels were greatest in 18 month rats (p < 0.05) despite the onset of atrophy, (c) while regulators of ribosome biogenesis [c-Myc and upstream binding factor (UBF) protein levels] generally increased with age, ribosome density linearly decreased from 3 months of age and RNA polymerase (Pol) I protein levels were lowest in 24 month rats, and d) 20S proteasome activity was robustly up-regulated in 6 and 24 month rats (p < 0.05). Notable soleus muscle observations included: (a) fiber CSA was greatest in 6 month rats and was maintained in older age groups, and (b) 20S proteasome activity was modestly but significantly greater in 24 month vs. 3/12/18 month rats (p < 0.05), and (c) total mRNA levels (suggestive of transcriptional output) trended downward in older rats despite non-significant between-group differences in myonuclear number and/or RNA Pol II protein levels. Collectively, these findings suggest that plantaris, not soleus, atrophy occurs following 12 months of age in male Fisher rats and this may be due to translational deficits (i.e., changes in MPS and ribosome density) and/or increases in proteolysis rather than increased oxidative stress and/or alterations in global transcriptional mechanisms.
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Affiliation(s)
| | - Petey W Mumford
- School of Kinesiology, Auburn UniversityAuburn, AL, United States
| | - Wesley C Kephart
- School of Kinesiology, Auburn UniversityAuburn, AL, United States
| | - Cody T Haun
- School of Kinesiology, Auburn UniversityAuburn, AL, United States
| | | | - Darren T Beck
- School of Kinesiology, Auburn UniversityAuburn, AL, United States.,Edward via College of Osteopathic MedicineAuburn, AL, United States
| | - Jeffrey S Martin
- School of Kinesiology, Auburn UniversityAuburn, AL, United States.,Edward via College of Osteopathic MedicineAuburn, AL, United States
| | - Kaelin C Young
- School of Kinesiology, Auburn UniversityAuburn, AL, United States.,Edward via College of Osteopathic MedicineAuburn, AL, United States
| | | | - Romil K Patel
- School of Kinesiology, Auburn UniversityAuburn, AL, United States
| | | | - Ryan P Lowery
- Applied Science and Performance InstituteTampa, FL, United States.,Department of Health and Human Performance, Concordia University ChicagoRiver Forest, IL, United States
| | - Jacob M Wilson
- Applied Science and Performance InstituteTampa, FL, United States
| | - Michael D Roberts
- School of Kinesiology, Auburn UniversityAuburn, AL, United States.,Edward via College of Osteopathic MedicineAuburn, AL, United States
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56
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Mobley CB, Holland AM, Kephart WC, Mumford PW, Lowery RP, Kavazis AN, Wilson JM, Roberts MD. Progressive resistance-loaded voluntary wheel running increases hypertrophy and differentially affects muscle protein synthesis, ribosome biogenesis, and proteolytic markers in rat muscle. J Anim Physiol Anim Nutr (Berl) 2017; 102:317-329. [DOI: 10.1111/jpn.12691] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 01/12/2017] [Indexed: 01/04/2023]
Affiliation(s)
| | | | | | | | - R. P. Lowery
- Applied Science and Performance Institute; Tampa FL USA
| | - A. N. Kavazis
- Auburn University; Auburn AL USA
- Edward Via College of Osteopathic Medicine - Auburn Campus; Auburn AL USA
| | - J. M. Wilson
- Applied Science and Performance Institute; Tampa FL USA
| | - M. D. Roberts
- Auburn University; Auburn AL USA
- Edward Via College of Osteopathic Medicine - Auburn Campus; Auburn AL USA
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57
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McGlory C, Devries MC, Phillips SM. Skeletal muscle and resistance exercise training; the role of protein synthesis in recovery and remodeling. J Appl Physiol (1985) 2016; 122:541-548. [PMID: 27742803 DOI: 10.1152/japplphysiol.00613.2016] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 10/04/2016] [Accepted: 10/05/2016] [Indexed: 12/22/2022] Open
Abstract
Exercise results in the rapid remodeling of skeletal muscle. This process is underpinned by acute and chronic changes in both gene and protein synthesis. In this short review we provide a brief summary of our current understanding regarding how exercise influences these processes as well as the subsequent impact on muscle protein turnover and resultant shift in muscle phenotype. We explore concepts of ribosomal biogenesis and the potential role of increased translational capacity vs. translational efficiency in contributing to muscular hypertrophy. We also examine whether high-intensity sprinting-type exercise promotes changes in protein turnover that lead to hypertrophy or merely a change in mitochondrial content. Finally, we propose novel areas for future study that will fill existing knowledge gaps in the fields of translational research and exercise science.
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Affiliation(s)
- Chris McGlory
- Department of Kinesiology, McMaster University, Ontario, Canada
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