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Fu S, Hu J, Wang G, Qian Z, Wang X. Androgen receptor regulates the differentiation of myoblasts under cyclic mechanical stretch and its upstream and downstream signals. Int J Biol Macromol 2024; 281:136257. [PMID: 39366623 DOI: 10.1016/j.ijbiomac.2024.136257] [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: 04/13/2024] [Revised: 06/30/2024] [Accepted: 10/01/2024] [Indexed: 10/06/2024]
Abstract
Our previous studies have demonstrated the important roles of androgen receptor (AR) in myoblast proliferation regulated by 15 % (mimic appropriate exercise) and 20 % (mimic excessive exercise) mechanical stretches. Except for myoblast proliferation, differentiation is also an important factor affecting muscle mass and strength. But the role of AR in stretch-regulated myoblast differentiation and AR's upstream and downstream signals remain unknown. In the present study, firstly the differences of myogenic differentiation between C2C12 (with AR expression) and L6 (without AR expression) myoblasts induced by 15 % and 20 % mechanical stretches were compared; secondly, AR antagonist flutamide and AR agonist GTx-007 were used in 15 % and 20 % stretched myoblasts respectively to confirm AR's roles in stretch-regulated myoblast differentiation; thirdly, RNA-seq, molecular dynamic simulation (MD) and co-immunoprecipitation were performed to screen the downstream and upstream molecules of AR during stretches. We found that (1) 15 % stretch increased while 20 % stretch decreased myotube number in differentiating C2C12 and L6 myoblasts, with more significant changes in C2C12 cells than L6 cells; (2) in stretched C2C12 myoblasts, AR antagonist flutamide inhibited 15 % stretch-promoted differentiation while AR agonist GTx-007 reversed 20 % stretch-inhibited differentiation (reflected by changes in myotube number, MHC contents of fast-twitch and slow-twitch fiber, and the levels of myogenic regulatory factors (MRFs) such as MyoD and myogenin); (3) KEGG analysis of RNA-seq showed that the differently expressed genes (DEGs) in C2C12 cells induced by 15 % stretch were enriched in FoxO and JAK-STAT signaling pathways, while DEGs by 20 % stretch were enriched in FoxO and MAPK signaling pathways; (4) MD and co-immunoprecipitation showed that β1 integrin could interact with AR and influence AR's activity in C2C12 cells. In conclusion, AR plays important roles in myoblast differentiation promoted by 15 % stretch while inhibited by 20 % stretch, which was fulfilled through FoxO-MRFs. In addition, α7β1 integrin may be a bridge linking mechanical stretch and AR. This study is beneficial to deeply understand the roles and mechanisms of AR in stretch-regulated muscle mass and strength; and reports firstly that myoblasts sense mechanical stimulus and transmit into intracellular AR via α7β1 integrin.
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Affiliation(s)
- Shaoting Fu
- School of Exercise and Health, Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai, China; Department of Kinesiology, College of Physical Education, Shanghai Normal University, Shanghai, China
| | - Jing Hu
- School of Exercise and Health, Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai, China
| | - Gang Wang
- School of Exercise and Health, Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai, China
| | - Zhenyu Qian
- School of Exercise and Health, Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai, China.
| | - Xiaohui Wang
- School of Exercise and Health, Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai, China.
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2
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Zhao YC, Gao BH. Integrative effects of resistance training and endurance training on mitochondrial remodeling in skeletal muscle. Eur J Appl Physiol 2024; 124:2851-2865. [PMID: 38981937 DOI: 10.1007/s00421-024-05549-5] [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: 01/06/2024] [Accepted: 07/03/2024] [Indexed: 07/11/2024]
Abstract
Resistance training activates mammalian target of rapamycin (mTOR) pathway of hypertrophy for strength gain, while endurance training increases peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) pathway of mitochondrial biogenesis benefiting oxidative phosphorylation. The conventional view suggests that resistance training-induced hypertrophy signaling interferes with endurance training-induced mitochondrial remodeling. However, this idea has been challenged because acute leg press and knee extension in humans enhance both muscle hypertrophy and mitochondrial remodeling signals. Thus, we first examined the muscle mitochondrial remodeling and hypertrophy signals with endurance training and resistance training, respectively. In addition, we discussed the influence of resistance training on muscle mitochondria, demonstrating that the PGC-1α-mediated muscle mitochondrial adaptation and hypertrophy occur simultaneously. The second aim was to discuss the integrative effects of concurrent training, which consists of endurance and resistance training sessions on mitochondrial remodeling. The study found that the resistance training component does not reduce muscle mitochondrial remodeling signals in concurrent training. On the contrary, concurrent training has the potential to amplify skeletal muscle mitochondrial biogenesis compared to a single exercise model. Concurrent training involving differential sequences of resistance and endurance training may result in varied mitochondrial biogenesis signals, which should be linked to the pre-activation of mTOR or PGC-1α signaling. Our review proposed a mechanism for mTOR signaling that promotes PGC-1α signaling through unidentified pathways. This mechanism may be account for the superior muscle mitochondrial remodeling change following the concurrent training. Our review suggested an interaction between resistance training and endurance training in skeletal muscle mitochondrial adaptation.
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Affiliation(s)
- Yong-Cai Zhao
- College of Exercise and Health, Tianjin University of Sport, No. 16 Donghai Road, Jinghai District, Tianjin, 301617, China.
| | - Bing-Hong Gao
- School of Athletic Performance, Shanghai University of Sport, No. 399 Changhai Road, Yangpu District, Shanghai, 200438, China
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3
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Cumming KT, Reitzner SM, Hanslien M, Skilnand K, Seynnes OR, Horwath O, Psilander N, Sundberg CJ, Raastad T. Muscle memory in humans: evidence for myonuclear permanence and long-term transcriptional regulation after strength training. J Physiol 2024; 602:4171-4193. [PMID: 39159314 DOI: 10.1113/jp285675] [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: 09/11/2023] [Accepted: 07/17/2024] [Indexed: 08/21/2024] Open
Abstract
The objective of this work was to investigate myonuclear permanence and transcriptional regulation as mechanisms for cellular muscle memory after strength training in humans. Twelve untrained men and women performed 10 weeks of unilateral elbow-flexor strength training followed by 16 weeks of de-training. Thereafter, 10 weeks' re-training was conducted with both arms: the previously trained arm and the contralateral untrained control arm. Muscle biopsies were taken from the trained arm before and after both training periods and from the control arm before and after re-training. Muscle biopsies were analysed for fibre cross-sectional area (fCSA), myonuclei and global transcriptomics (RNA sequencing). During the first training period, myonuclei increased in type 1 (13 ± 17%) and type 2 (33 ± 23%) fibres together with a 30 ± 43% non-significant increase in mixed fibre fCSA (P = 0.069). Following de-training, fCSA decreased in both fibre types, whereas myonuclei were maintained, resulting in 33% higher myonuclear number in previously trained vs. control muscle in type 2 fibres. Furthermore, in the previously trained muscle, three differentially expressed genes (DEGs; EGR1, MYL5 and COL1A1) were observed. Following re-training, the previously trained muscle showed larger type 2 fCSA compared to the control (P = 0.035). However, delta change in type 2 fCSA was not different between muscles. Gene expression was more dramatically changed in the control arm (1338 DEGs) than in the previously trained arm (822 DEGs). The sustained higher number of myonuclei in the previously trained muscle confirms myonuclear accretion and permanence in humans. Nevertheless, because of the unclear effect on the subsequent hypertrophy with re-training, the physiological benefit remains to be determined. KEY POINTS: Muscle memory is a cellular mechanism that describes the capacity of skeletal muscle fibres to respond differently to training stimuli if the stimuli have been previously encountered. This study overcomes past methodological limitations related to the choice of muscles and analytical procedures. We show that myonuclear number is increased after strength training and maintained during de-training. Increased myonuclear number and differentially expressed genes related to muscle performance and development in the previously trained muscle did not translate into a clearly superior responses during re-training. Because of the unclear effect on the subsequent hypertrophy and muscle strength gain with re-training, the physiological benefit remains to be determined.
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Affiliation(s)
- Kristoffer Toldnes Cumming
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
- Faculty of Health, Welfare and Organisation, Østfold University College, Fredrikstad, Norway
| | - Stefan Markus Reitzner
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Marit Hanslien
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Kenneth Skilnand
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Olivier R Seynnes
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Oscar Horwath
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Niklas Psilander
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Carl Johan Sundberg
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
- Department of Learning, Informatics, Management and Ethics, Karolinska Institutet, Stockholm, Sweden
| | - Truls Raastad
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
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4
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Burke BI, Ismaeel A, McCarthy JJ. The utility of the rodent synergist ablation model in identifying molecular and cellular mechanisms of skeletal muscle hypertrophy. Am J Physiol Cell Physiol 2024; 327:C601-C606. [PMID: 39069822 PMCID: PMC11427019 DOI: 10.1152/ajpcell.00362.2024] [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: 05/29/2024] [Revised: 06/16/2024] [Accepted: 06/17/2024] [Indexed: 07/30/2024]
Abstract
Skeletal muscle exhibits remarkable plasticity to adapt to stimuli such as mechanical loading. The mechanisms that regulate skeletal muscle hypertrophy due to mechanical overload have been thoroughly studied. Remarkably, our understanding of many of the molecular and cellular mechanisms that regulate hypertrophic growth were first identified using the rodent synergist ablation (SA) model and subsequently corroborated in human resistance exercise training studies. To demonstrate the utility of the SA model, we briefly summarize the hypertrophic mechanisms identified using the model and the following translation of these mechanism to human skeletal muscle hypertrophy induced by resistance exercise training.
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Affiliation(s)
- Benjamin I Burke
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, United States
| | - Ahmed Ismaeel
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, United States
| | - John J McCarthy
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, United States
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5
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Lin KH, Hibbert JE, Flynn CG, Lemens JL, Torbey MM, Steinert ND, Flejsierowicz PM, Melka KM, Lindley GT, Lares M, Setaluri V, Wagers AJ, Hornberger TA. Satellite cell-derived TRIM28 is pivotal for mechanical load- and injury-induced myogenesis. EMBO Rep 2024; 25:3812-3841. [PMID: 39143258 PMCID: PMC11387408 DOI: 10.1038/s44319-024-00227-1] [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: 01/04/2024] [Revised: 07/19/2024] [Accepted: 07/26/2024] [Indexed: 08/16/2024] Open
Abstract
Satellite cells are skeletal muscle stem cells that contribute to postnatal muscle growth, and they endow skeletal muscle with the ability to regenerate after a severe injury. Here we discover that this myogenic potential of satellite cells requires a protein called tripartite motif-containing 28 (TRIM28). Interestingly, different from the role reported in a previous study based on C2C12 myoblasts, multiple lines of both in vitro and in vivo evidence reveal that the myogenic function of TRIM28 is not dependent on changes in the phosphorylation of its serine 473 residue. Moreover, the functions of TRIM28 are not mediated through the regulation of satellite cell proliferation or differentiation. Instead, our findings indicate that TRIM28 regulates the ability of satellite cells to progress through the process of fusion. Specifically, we discover that TRIM28 controls the expression of a fusogenic protein called myomixer and concomitant fusion pore formation. Collectively, the outcomes of this study expose the framework of a novel regulatory pathway that is essential for myogenesis.
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Affiliation(s)
- Kuan-Hung Lin
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA
| | - Jamie E Hibbert
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA
| | - Corey Gk Flynn
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA
| | - Jake L Lemens
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA
| | - Melissa M Torbey
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA
| | - Nathaniel D Steinert
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA
| | - Philip M Flejsierowicz
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA
| | - Kiley M Melka
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA
| | - Garrison T Lindley
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA
| | - Marcos Lares
- Department of Dermatology, University of Wisconsin - Madison, Madison, WI, USA
| | | | - Amy J Wagers
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA
- Harvard Stem Cell Institute, Cambridge, MA, USA
- Joslin Diabetes Center, Boston, MA, USA
| | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin - Madison, Madison, WI, USA.
- School of Veterinary Medicine, University of Wisconsin - Madison, Madison, WI, USA.
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6
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Betz MW, De Brandt J, Aussieker T, Monsegue AP, Houtvast DCJ, Gehlert S, Verdijk LB, van Loon LJC, Gosker HR, Langen RJC, Derave W, Burtin C, Spruit MA, Snijders T. Muscle fibre satellite cells are located at a greater distance from capillaries in patients with COPD compared with healthy controls. ERJ Open Res 2024; 10:00203-2024. [PMID: 39351378 PMCID: PMC11440426 DOI: 10.1183/23120541.00203-2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 05/13/2024] [Indexed: 10/04/2024] Open
Abstract
Background COPD is a disease characterised by skeletal muscle dysfunction. A spatial relationship exists between satellite cells and muscle fibre capillaries, which has been suggested to be of major importance for satellite cell function. In the present study we compared the spatial relationship between satellite cells and capillaries in patients with COPD and age-matched healthy older adults. Methods Muscle biopsies were obtained from the vastus lateralis of n=18 patients with COPD (8 female, 10 male; age 66±5 years, mild-to-severe airflow obstruction) and n=18 age-, sex- and body mass index-matched healthy control adults (8 female, 10 male; age 68±5 years). Immunohistochemistry was used to assess type I/II muscle fibre size, distribution, myonuclear content, satellite cell number and fibre capillarisation. In addition, type I/II muscle fibre satellite cell distance to its nearest capillary was assessed. Results The percentage of type II muscle fibres was significantly greater in patients with COPD (62±10%) compared with controls (50±12%, p<0.05). Muscle fibre capillarisation was significantly lower in patients with COPD compared with controls (p<0.05). While satellite cell content was not different between groups, type I and type II satellite cell distance to its nearest capillary was significantly greater in patients with COPD (type I: 21.3±4.8 µm; type II: 26.7±9.3 µm) compared with controls (type I: 16.1±3.5 µm; type II: 22.7±5.8 µm; p<0.05). Conclusion Satellite cells are located at a greater distance from their nearest capillary in patients with COPD compared with age-matched controls. This increased distance could play a role in impaired satellite cell function in patients with COPD.
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Affiliation(s)
- Milan W Betz
- NUTRIM Research Institute of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Biology, Maastricht, The Netherlands
| | - Jana De Brandt
- Faculty of Rehabilitation Sciences, REVAL - Rehabilitation Research Center, BIOMED - Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Thorben Aussieker
- NUTRIM Research Institute of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Biology, Maastricht, The Netherlands
| | - Alejandra P Monsegue
- NUTRIM Research Institute of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Biology, Maastricht, The Netherlands
| | - Dion C J Houtvast
- NUTRIM Research Institute of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Biology, Maastricht, The Netherlands
| | - Sebastian Gehlert
- Department for Biosciences of Sports, Institute for Sport Science, University of Hildesheim, Hildesheim, Germany
| | - Lex B Verdijk
- NUTRIM Research Institute of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Biology, Maastricht, The Netherlands
| | - Luc J C van Loon
- NUTRIM Research Institute of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Biology, Maastricht, The Netherlands
| | - Harry R Gosker
- NUTRIM, Maastricht University Medical Centre+, Department of Respiratory Medicine, Maastricht, The Netherlands
| | - Ramon J C Langen
- NUTRIM, Maastricht University Medical Centre+, Department of Respiratory Medicine, Maastricht, The Netherlands
| | - Wim Derave
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Chris Burtin
- Faculty of Rehabilitation Sciences, REVAL - Rehabilitation Research Center, BIOMED - Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Martijn A Spruit
- NUTRIM, Maastricht University Medical Centre+, Department of Respiratory Medicine, Maastricht, The Netherlands
- Department of Research and Education, CIRO+, Horn, The Netherlands
| | - Tim Snijders
- NUTRIM Research Institute of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Biology, Maastricht, The Netherlands
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7
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Saliu TP, Goh J, Kang G, Burke BI, Ismaeel A, McCarthy JJ. Satellite cell dynamics during skeletal muscle hypertrophy. Biochem Soc Trans 2024; 52:1921-1926. [PMID: 39136196 DOI: 10.1042/bst20240201] [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: 06/26/2024] [Revised: 07/26/2024] [Accepted: 07/30/2024] [Indexed: 08/26/2024]
Abstract
Skeletal muscle stem cells (MuSCs) display distinct behavior crucial for tissue maintenance and repair. Upon activation, MuSCs exhibit distinct modes of division: symmetric division, facilitating either self-renewal or differentiation, and asymmetric division, which dictates divergent cellular fates. This review explores the nuanced dynamics of MuSC division and the molecular mechanisms governing this behavior. Furthermore, it introduces a novel phenomenon observed in a subset of MuSCs under hypertrophic stimuli termed division-independent differentiation. Insights into the underlying mechanisms driving this process are discussed, alongside its broader implications for muscle physiology.
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Affiliation(s)
- Tolulope P Saliu
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, U.S.A
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, U.S.A
| | - Jensen Goh
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, U.S.A
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, U.S.A
| | - Gyumin Kang
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, U.S.A
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, U.S.A
- Division of Biomedical Informatics, Department of Internal Medicine, College of Medicine, University of Kentucky, Lexington, KY, U.S.A
| | - Benjamin I Burke
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, U.S.A
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, U.S.A
| | - Ahmed Ismaeel
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, U.S.A
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, U.S.A
| | - John J McCarthy
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, U.S.A
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, U.S.A
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8
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Soro-Arnáiz I, Fitzgerald G, Cherkaoui S, Zhang J, Gilardoni P, Ghosh A, Bar-Nur O, Masschelein E, Maechler P, Zamboni N, Poms M, Cremonesi A, Garcia-Cañaveras JC, De Bock K, Morscher RJ. GLUD1 determines murine muscle stem cell fate by controlling mitochondrial glutamate levels. Dev Cell 2024:S1534-5807(24)00455-6. [PMID: 39121856 DOI: 10.1016/j.devcel.2024.07.015] [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: 11/09/2023] [Revised: 04/04/2024] [Accepted: 07/16/2024] [Indexed: 08/12/2024]
Abstract
Muscle stem cells (MuSCs) enable muscle growth and regeneration after exercise or injury, but how metabolism controls their regenerative potential is poorly understood. We describe that primary metabolic changes can determine murine MuSC fate decisions. We found that glutamine anaplerosis into the tricarboxylic acid (TCA) cycle decreases during MuSC differentiation and coincides with decreased expression of the mitochondrial glutamate deaminase GLUD1. Deletion of Glud1 in proliferating MuSCs resulted in precocious differentiation and fusion, combined with loss of self-renewal in vitro and in vivo. Mechanistically, deleting Glud1 caused mitochondrial glutamate accumulation and inhibited the malate-aspartate shuttle (MAS). The resulting defect in transporting NADH-reducing equivalents into the mitochondria induced compartment-specific NAD+/NADH ratio shifts. MAS activity restoration or directly altering NAD+/NADH ratios normalized myogenesis. In conclusion, GLUD1 prevents deleterious mitochondrial glutamate accumulation and inactivation of the MAS in proliferating MuSCs. It thereby acts as a compartment-specific metabolic brake on MuSC differentiation.
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Affiliation(s)
- Inés Soro-Arnáiz
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zurich), Schwerzenbach, 8603 Zurich, Switzerland
| | - Gillian Fitzgerald
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zurich), Schwerzenbach, 8603 Zurich, Switzerland; Pediatric Cancer Metabolism Laboratory, Children's Research Center, University of Zurich, 8032 Zurich, Switzerland; Division of Oncology, University Children's Hospital Zurich and Children's Research Center, University of Zurich, 8032 Zurich, Switzerland
| | - Sarah Cherkaoui
- Pediatric Cancer Metabolism Laboratory, Children's Research Center, University of Zurich, 8032 Zurich, Switzerland; Division of Oncology, University Children's Hospital Zurich and Children's Research Center, University of Zurich, 8032 Zurich, Switzerland
| | - Jing Zhang
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zurich), Schwerzenbach, 8603 Zurich, Switzerland
| | - Paola Gilardoni
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zurich), Schwerzenbach, 8603 Zurich, Switzerland
| | - Adhideb Ghosh
- Laboratory of Regenerative and Movement Biology, Department of Health Sciences and Technology, ETH Zurich, Schwerzenbach, 8603 Zurich, Switzerland; Functional Genomics Center Zurich, ETH Zurich and University of Zurich, 8032 Zurich, Switzerland
| | - Ori Bar-Nur
- Laboratory of Regenerative and Movement Biology, Department of Health Sciences and Technology, ETH Zurich, Schwerzenbach, 8603 Zurich, Switzerland
| | - Evi Masschelein
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zurich), Schwerzenbach, 8603 Zurich, Switzerland
| | - Pierre Maechler
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, 1211 Geneva, Switzerland
| | - Nicola Zamboni
- Institute of Molecular Systems Biology, ETH Zurich, 8049 Zurich, Switzerland
| | - Martin Poms
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, University of Zurich, 8032 Zurich, Switzerland
| | - Alessio Cremonesi
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, University of Zurich, 8032 Zurich, Switzerland
| | | | - Katrien De Bock
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zurich), Schwerzenbach, 8603 Zurich, Switzerland.
| | - Raphael Johannes Morscher
- Pediatric Cancer Metabolism Laboratory, Children's Research Center, University of Zurich, 8032 Zurich, Switzerland; Division of Oncology, University Children's Hospital Zurich and Children's Research Center, University of Zurich, 8032 Zurich, Switzerland; Division of Human Genetics, Medical University Innsbruck, 6020 Innsbruck, Austria.
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9
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Korb A, Tajbakhsh S, Comai GE. Functional specialisation and coordination of myonuclei. Biol Rev Camb Philos Soc 2024; 99:1164-1195. [PMID: 38477382 DOI: 10.1111/brv.13063] [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: 04/10/2023] [Revised: 01/30/2024] [Accepted: 02/02/2024] [Indexed: 03/14/2024]
Abstract
Myofibres serve as the functional unit for locomotion, with the sarcomere as fundamental subunit. Running the entire length of this structure are hundreds of myonuclei, located at the periphery of the myofibre, juxtaposed to the plasma membrane. Myonuclear specialisation and clustering at the centre and ends of the fibre are known to be essential for muscle contraction, yet the molecular basis of this regionalisation has remained unclear. While the 'myonuclear domain hypothesis' helped explain how myonuclei can independently govern large cytoplasmic territories, novel technologies have provided granularity on the diverse transcriptional programs running simultaneously within the syncytia and added a new perspective on how myonuclei communicate. Building upon this, we explore the critical cellular and molecular sources of transcriptional and functional heterogeneity within myofibres, discussing the impact of intrinsic and extrinsic factors on myonuclear programs. This knowledge provides new insights for understanding muscle development, repair, and disease, but also opens avenues for the development of novel and precise therapeutic approaches.
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Affiliation(s)
- Amaury Korb
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
| | - Shahragim Tajbakhsh
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
| | - Glenda E Comai
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
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10
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Madigan LA, Jaime D, Chen I, Fallon JR. MuSK-BMP signaling in adult muscle stem cells maintains quiescence and regulates myofiber size. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.17.541238. [PMID: 37292636 PMCID: PMC10245747 DOI: 10.1101/2023.05.17.541238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A central question in adult stem cell biology is elucidating the signaling pathways regulating their dynamics and function in diverse physiological and age-related contexts. Muscle stem cells in adults (Satellite Cells; SCs) are generally quiescent but can activate and contribute to muscle repair and growth. Here we tested the role of the MuSK-BMP pathway in regulating adult SC quiescence by deletion of the BMP-binding MuSK Ig3 domain ('ΔIg3-MuSK'). At 3 months of age SC and myonuclei numbers and myofiber size were comparable to WT. However, at 5 months of age SC density was decreased while myofiber size, myonuclear number and grip strength were increased - indicating that SCs had activated and productively fused into the myofibers over this interval. Transcriptomic analysis showed that SCs from uninjured ΔIg3-MuSK mice exhibit signatures of activation. Regeneration experiments showed that ΔIg3-MuSK SCs maintain full stem cell function. Expression of ΔIg3-MuSK in adult SCs was sufficient to break quiescence and increase myofiber size. We conclude that the MuSK-BMP pathway regulates SC quiescence and myofiber size in a cell autonomous, age-dependent manner. Targeting MuSK-BMP signaling in muscle stem cells thus emerges a therapeutic strategy for promoting muscle growth and function in the settings of injury, disease, and aging. Highlights MuSK, in its role as a BMP co-receptor, regulates adult muscle stem cell quiescenceThe MuSK-BMP pathway acts cell autonomouslyIncreased muscle size and function with preservation of myonuclear density and stemness in mice with attenuated MuSK-BMP signaling.
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11
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Millward DJ. Post-natal muscle growth and protein turnover: a narrative review of current understanding. Nutr Res Rev 2024; 37:141-168. [PMID: 37395180 DOI: 10.1017/s0954422423000124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
A model explaining the dietary-protein-driven post-natal skeletal muscle growth and protein turnover in the rat is updated, and the mechanisms involved are described, in this narrative review. Dietary protein controls both bone length and muscle growth, which are interrelated through mechanotransduction mechanisms with muscle growth induced both from stretching subsequent to bone length growth and from internal work against gravity. This induces satellite cell activation, myogenesis and remodelling of the extracellular matrix, establishing a growth capacity for myofibre length and cross-sectional area. Protein deposition within this capacity is enabled by adequate dietary protein and other key nutrients. After briefly reviewing the experimental animal origins of the growth model, key concepts and processes important for growth are reviewed. These include the growth in number and size of the myonuclear domain, satellite cell activity during post-natal development and the autocrine/paracrine action of IGF-1. Regulatory and signalling pathways reviewed include developmental mechanotransduction, signalling through the insulin/IGF-1-PI3K-Akt and the Ras-MAPK pathways in the myofibre and during mechanotransduction of satellite cells. Likely pathways activated by maximal-intensity muscle contractions are highlighted and the regulation of the capacity for protein synthesis in terms of ribosome assembly and the translational regulation of 5-TOPmRNA classes by mTORC1 and LARP1 are discussed. Evidence for and potential mechanisms by which volume limitation of muscle growth can occur which would limit protein deposition within the myofibre are reviewed. An understanding of how muscle growth is achieved allows better nutritional management of its growth in health and disease.
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Affiliation(s)
- D Joe Millward
- Department of Nutritional Sciences, School of Biosciences & Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
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12
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Dugdale HF, Levy Y, Jungbluth H, Oldfors A, Ochala J. Aberrant myonuclear domains and impaired myofiber contractility despite marked hypertrophy in MYMK-related, Carey-Fineman-Ziter Syndrome. Acta Neuropathol Commun 2024; 12:80. [PMID: 38790073 PMCID: PMC11127446 DOI: 10.1186/s40478-024-01783-2] [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: 02/09/2024] [Accepted: 04/10/2024] [Indexed: 05/26/2024] Open
Abstract
Carey Fineman Ziter Syndrome (CFZS) is a rare autosomal recessive disease caused by mutations in the MYMK locus which encodes the protein, myomaker. Myomaker is essential for fusion and concurrent myonuclei donation of muscle progenitors during growth and development. Strikingly, in humans, MYMK mutations appear to prompt myofiber hypertrophy but paradoxically, induce generalised muscle weakness. As the underlying cellular mechanisms remain unexplored, the present study aimed to gain insights by combining myofiber deep-phenotyping and proteomic profiling. Hence, we isolated individual muscle fibers from CFZS patients and performed mechanical, 3D morphological and proteomic analyses. Myofibers from CFZS patients were ~ 4x larger than controls and possessed ~ 2x more myonuclei than those from healthy subjects, leading to disproportionally larger myonuclear domain volumes. These greater myonuclear domain sizes were accompanied by smaller intrinsic cellular force generating-capacities in myofibers from CFZS patients than in control muscle cells. Our complementary proteomic analyses indicated remodelling in 233 proteins particularly those associated with cellular respiration. Overall, our findings suggest that myomaker is somewhat functional in CFZS patients, but the associated nuclear accretion may ultimately lead to non-functional hypertrophy and altered energy-related mechanisms in CFZS patients. All of these are likely contributors of the muscle weakness experienced by CFZS patients.
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Affiliation(s)
- Hannah F Dugdale
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- Centre for Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Yotam Levy
- Centre for Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Heinz Jungbluth
- Randall Centre for Cell and Molecular Biophysics, Muscle Signalling Section, Faculty of Life Sciences and Medicine (FoLSM), King's College London, London, UK
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, Guy's and St Thomas' Hospital NHS Foundation Trust, London, UK
| | - Anders Oldfors
- Department of Laboratory Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Julien Ochala
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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13
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Gu S, Wen C, Xiao Z, Huang Q, Jiang Z, Liu H, Gao J, Li J, Sun C, Yang N. MyoV: a deep learning-based tool for the automated quantification of muscle fibers. Brief Bioinform 2024; 25:bbad528. [PMID: 38271484 PMCID: PMC10810329 DOI: 10.1093/bib/bbad528] [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: 09/25/2023] [Revised: 12/06/2023] [Accepted: 12/15/2023] [Indexed: 01/27/2024] Open
Abstract
Accurate approaches for quantifying muscle fibers are essential in biomedical research and meat production. In this study, we address the limitations of existing approaches for hematoxylin and eosin-stained muscle fibers by manually and semiautomatically labeling over 660 000 muscle fibers to create a large dataset. Subsequently, an automated image segmentation and quantification tool named MyoV is designed using mask regions with convolutional neural networks and a residual network and feature pyramid network as the backbone network. This design enables the tool to allow muscle fiber processing with different sizes and ages. MyoV, which achieves impressive detection rates of 0.93-0.96 and precision levels of 0.91-0.97, exhibits a superior performance in quantification, surpassing both manual methods and commonly employed algorithms and software, particularly for whole slide images (WSIs). Moreover, MyoV is proven as a powerful and suitable tool for various species with different muscle development, including mice, which are a crucial model for muscle disease diagnosis, and agricultural animals, which are a significant meat source for humans. Finally, we integrate this tool into visualization software with functions, such as segmentation, area determination and automatic labeling, allowing seamless processing for over 400 000 muscle fibers within a WSI, eliminating the model adjustment and providing researchers with an easy-to-use visual interface to browse functional options and realize muscle fiber quantification from WSIs.
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Affiliation(s)
- Shuang Gu
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100193, China
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Chaoliang Wen
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100193, China
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
- Sanya Institute of China Agricultural University, Hainan 572025, China
| | - Zhen Xiao
- School of Computer and Information, Hefei University of Technology, Anhui 230009, China
| | - Qiang Huang
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100193, China
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Zheyi Jiang
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100193, China
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Honghong Liu
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100193, China
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Jia Gao
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100193, China
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Junying Li
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100193, China
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
- Sanya Institute of China Agricultural University, Hainan 572025, China
| | - Congjiao Sun
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100193, China
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
- Sanya Institute of China Agricultural University, Hainan 572025, China
| | - Ning Yang
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100193, China
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
- Sanya Institute of China Agricultural University, Hainan 572025, China
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14
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Lin KH, Hibbert JE, Lemens JL, Torbey MM, Steinert ND, Flejsierowicz PM, Melka KM, Lares M, Setaluri V, Hornberger TA. The role of satellite cell-derived TRIM28 in mechanical load- and injury-induced myogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.20.572566. [PMID: 38187693 PMCID: PMC10769277 DOI: 10.1101/2023.12.20.572566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Satellite cells are skeletal muscle stem cells that contribute to postnatal muscle growth, and they endow skeletal muscle with the ability to regenerate after a severe injury. Here we discovered that this myogenic potential of satellite cells requires a protein called tripartite motif-containing 28 (TRIM28). Unexpectedly, multiple lines of both in vitro and in vivo evidence revealed that the myogenic function of TRIM28 is not dependent on changes in the phosphorylation of its serine 473 residue. Moreover, the functions of TRIM28 were not mediated through the regulation of satellite cell proliferation or differentiation. Instead, our findings indicate that TRIM28 regulates the ability of satellite cells to progress through the process of fusion. Specifically, we discovered that TRIM28 controls the expression of a fusogenic protein called myomixer and concomitant fusion pore formation. Collectively, the outcomes of this study expose the framework of a novel regulatory pathway that is essential for myogenesis.
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Affiliation(s)
- Kuan-Hung Lin
- Department of Comparative Biosciences, University of Wisconsin - Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, WI, USA
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA
| | - Jamie E. Hibbert
- Department of Comparative Biosciences, University of Wisconsin - Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, WI, USA
| | - Jake L. Lemens
- Department of Comparative Biosciences, University of Wisconsin - Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, WI, USA
| | - Melissa M. Torbey
- Department of Comparative Biosciences, University of Wisconsin - Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, WI, USA
| | - Nathaniel D. Steinert
- Department of Comparative Biosciences, University of Wisconsin - Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, WI, USA
| | - Philip M. Flejsierowicz
- Department of Comparative Biosciences, University of Wisconsin - Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, WI, USA
| | - Kiley M. Melka
- Department of Comparative Biosciences, University of Wisconsin - Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, WI, USA
| | - Marcos Lares
- Department of Dermatology, University of Wisconsin - Madison, WI, USA
| | | | - Troy A. Hornberger
- Department of Comparative Biosciences, University of Wisconsin - Madison, WI, USA
- School of Veterinary Medicine, University of Wisconsin - Madison, WI, USA
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15
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Ochi E, Barrington A, Wehling‐Henricks M, Avila M, Kuro‐o M, Tidball JG. Klotho regulates the myogenic response of muscle to mechanical loading and exercise. Exp Physiol 2023; 108:1531-1547. [PMID: 37864311 PMCID: PMC10841225 DOI: 10.1113/ep091263] [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: 04/14/2023] [Accepted: 08/16/2023] [Indexed: 10/22/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does the hormone Klotho affect the myogenic response of muscle cells to mechanical loading or exercise? What is the main finding and its importance? Klotho prevents direct, mechanical activation of genes that regulate muscle differentiation, including genes that encode the myogenic regulatory factor myogenin and proteins in the canonical Wnt signalling pathway. Similarly, elevated levels of klotho expression in vivo prevent the exercise-induced increase in myogenin-expressing cells and reduce exercise-induced activation of the Wnt pathway. These findings demonstrate a new mechanism through which the responses of muscle to the mechanical environment are regulated. ABSTRACT Muscle growth is influenced by changes in the mechanical environment that affect the expression of genes that regulate myogenesis. We tested whether the hormone Klotho could influence the response of muscle to mechanical loading. Applying mechanical loads to myoblasts in vitro increased RNA encoding transcription factors that are expressed in activated myoblasts (Myod) and in myogenic cells that have initiated terminal differentiation (Myog). However, application of Klotho to myoblasts prevented the loading-induced activation of Myog without affecting loading-induced activation of Myod. This indicates that elevated Klotho inhibits mechanically-induced differentiation of myogenic cells. Elevated Klotho also reduced the transcription of genes encoding proteins involved in the canonical Wnt pathway or their target genes (Wnt9a, Wnt10a, Ccnd1). Because the canonical Wnt pathway promotes differentiation of myogenic cells, these findings indicate that Klotho inhibits the differentiation of myogenic cells experiencing mechanical loading. We then tested whether these effects of Klotho occurred in muscles of mice experiencing high-intensity interval training (HIIT) by comparing wild-type mice and klotho transgenic mice. The expression of a klotho transgene combined with HIIT synergized to tremendously elevate numbers of Pax7+ satellite cells and activated MyoD+ cells. However, transgene expression prevented the increase in myogenin+ cells caused by HIIT in wild-type mice. Furthermore, transgene expression diminished the HIIT-induced activation of the canonical Wnt pathway in Pax7+ satellite cells. Collectively, these findings show that Klotho inhibits loading- or exercise-induced activation of muscle differentiation and indicate a new mechanism through which the responses of muscle to the mechanical environment are regulated.
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Affiliation(s)
- Eisuke Ochi
- Faculty of Bioscience and Applied ChemistryHosei UniversityTokyoJapan
- Department of Integrative Biology and PhysiologyUniversity of CaliforniaLos AngelesCAUSA
| | - Alice Barrington
- Department of Integrative Biology and PhysiologyUniversity of CaliforniaLos AngelesCAUSA
| | | | - Marcus Avila
- Department of Integrative Biology and PhysiologyUniversity of CaliforniaLos AngelesCAUSA
| | - Makoto Kuro‐o
- Division of Anti‐Aging MedicineCenter for Molecular MedicineJichi Medical UniversityTochigiJapan
| | - James G. Tidball
- Department of Integrative Biology and PhysiologyUniversity of CaliforniaLos AngelesCAUSA
- Molecular, Cellular & Integrative Physiology ProgramUniversity of CaliforniaLos AngelesCAUSA
- Department of BioengineeringUniversity of CaliforniaLos AngelesCAUSA
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLAUniversity of CaliforniaLos AngelesCAUSA
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16
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O’Connor TN, Zhao N, Orciuoli HM, Brasile A, Pietrangelo L, He M, Groom L, Leigh J, Mahamed Z, Liang C, Malik S, Protasi F, Dirksen RT. Voluntary wheel running mitigates disease in an Orai1 gain-of-function mouse model of tubular aggregate myopathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.29.559036. [PMID: 37808709 PMCID: PMC10557777 DOI: 10.1101/2023.09.29.559036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Tubular aggregate myopathy (TAM) is an inherited skeletal muscle disease associated with progressive muscle weakness, cramps, and myalgia. Tubular aggregates (TAs) are regular arrays of highly ordered and densely packed SR straight-tubes in muscle biopsies; the extensive presence of TAs represent a key histopathological hallmark of this disease in TAM patients. TAM is caused by gain-of-function mutations in proteins that coordinate store-operated Ca2+ entry (SOCE): STIM1 Ca2+ sensor proteins in the sarcoplasmic reticulum (SR) and Ca2+-permeable ORAI1 channels in the surface membrane. We have previously shown that voluntary wheel running (VWR) prevents formation of TAs in aging mice. Here, we assessed the therapeutic potential of endurance exercise (in the form of VWR) in mitigating the functional and structural alterations in a knock-in mouse model of TAM (Orai1G100S/+ or GS mice) based on a gain-of-function mutation in the ORAI1 pore. WT and GS mice were singly-housed for six months (from two to eight months of age) with either free-spinning or locked low profile wheels. Six months of VWR exercise significantly increased soleus peak tetanic specific force production, normalized FDB fiber Ca2+ store content, and markedly reduced TAs in EDL muscle from GS mice. Six months of VWR exercise normalized the expression of mitochondrial proteins found to be altered in soleus muscle of sedentary GS mice in conjunction with a signature of increased protein translation and biosynthetic processes. Parallel proteomic analyses of EDL muscles from sedentary WT and GS mice revealed changes in a tight network of pathways involved in formation of supramolecular complexes, which were also normalized following six months of VWR. In summary, sustained voluntary endurance exercise improved slow twitch muscle function, reduced the presence of TAs in fast twitch muscle, and normalized the muscle proteome of GS mice consistent with protective adaptions in proteostasis, mitochondrial structure/function, and formation of supramolecular complexes.
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Affiliation(s)
- Thomas N. O’Connor
- Department of Biomedical Genetics, Genetics and Genomics Graduate Program, University of Rochester Medical Center, Rochester, NY, USA
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Nan Zhao
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Haley M. Orciuoli
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
- Department of Biology, Biological Sciences, University of Rochester, Rochester, NY, USA
| | - Alice Brasile
- CAST, Center for Advanced Studies and Technology & DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Laura Pietrangelo
- CAST, Center for Advanced Studies and Technology & DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Miao He
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Linda Groom
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Jennifer Leigh
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Zahra Mahamed
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Chen Liang
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Sundeep Malik
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Feliciano Protasi
- CAST, Center for Advanced Studies and Technology & DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Robert T. Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
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Sun C, Swoboda CO, Petrany MJ, Parameswaran S, VonHandorf A, Weirauch MT, Lepper C, Millay DP. Lineage tracing of newly accrued nuclei in skeletal myofibers uncovers distinct transcripts and interplay between nuclear populations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.24.554609. [PMID: 37662191 PMCID: PMC10473681 DOI: 10.1101/2023.08.24.554609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Multinucleated skeletal muscle cells have an obligatory need to acquire additional nuclei through fusion with activated skeletal muscle stem cells when responding to both developmental and adaptive growth stimuli. A fundamental question in skeletal muscle biology has been the reason underlying this need for new nuclei in syncytial cells that already harbor hundreds of nuclei. To begin to answer this long-standing question, we utilized nuclear RNA-sequencing approaches and developed a lineage tracing strategy capable of defining the transcriptional state of recently fused nuclei and distinguishing this state from that of pre-existing nuclei. Our findings reveal the presence of conserved markers of newly fused nuclei both during development and after a hypertrophic stimulus in the adult. However, newly fused nuclei also exhibit divergent gene expression that is determined by the myogenic environment to which they fuse. Moreover, accrual of new nuclei through fusion is required for nuclei already resident in adult myofibers to mount a normal transcriptional response to a load-inducing stimulus. We propose a model of mutual regulation in the control of skeletal muscle development and adaptations, where newly fused and pre-existing myonuclear populations influence each other to maintain optimal functional growth.
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Affiliation(s)
- Chengyi Sun
- Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Casey O. Swoboda
- Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Michael J. Petrany
- Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Sreeja Parameswaran
- Division of Human Genetics, Center for Autoimmune Genetics and Etiology (CAGE), Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Andrew VonHandorf
- Division of Human Genetics, Center for Autoimmune Genetics and Etiology (CAGE), Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Matthew T. Weirauch
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
- Division of Human Genetics, Center for Autoimmune Genetics and Etiology (CAGE), Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Christoph Lepper
- Department of Physiology & Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Douglas P. Millay
- Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
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18
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Pizza FX, Buckley KH. Regenerating Myofibers after an Acute Muscle Injury: What Do We Really Know about Them? Int J Mol Sci 2023; 24:12545. [PMID: 37628725 PMCID: PMC10454182 DOI: 10.3390/ijms241612545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/02/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
Injury to skeletal muscle through trauma, physical activity, or disease initiates a process called muscle regeneration. When injured myofibers undergo necrosis, muscle regeneration gives rise to myofibers that have myonuclei in a central position, which contrasts the normal, peripheral position of myonuclei. Myofibers with central myonuclei are called regenerating myofibers and are the hallmark feature of muscle regeneration. An important and underappreciated aspect of muscle regeneration is the maturation of regenerating myofibers into a normal sized myofiber with peripheral myonuclei. Strikingly, very little is known about processes that govern regenerating myofiber maturation after muscle injury. As knowledge of myofiber formation and maturation during embryonic, fetal, and postnatal development has served as a foundation for understanding muscle regeneration, this narrative review discusses similarities and differences in myofiber maturation during muscle development and regeneration. Specifically, we compare and contrast myonuclear positioning, myonuclear accretion, myofiber hypertrophy, and myofiber morphology during muscle development and regeneration. We also discuss regenerating myofibers in the context of different types of myofiber necrosis (complete and segmental) after muscle trauma and injurious contractions. The overall goal of the review is to provide a framework for identifying cellular and molecular processes of myofiber maturation that are unique to muscle regeneration.
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Affiliation(s)
- Francis X. Pizza
- Department of Exercise and Rehabilitation Sciences, University of Toledo, Toledo, OH 43606, USA
| | - Kole H. Buckley
- Division of Gastroenterology and Hepatology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA;
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19
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Hansson KA, Eftestøl E. Scaling of nuclear numbers and their spatial arrangement in skeletal muscle cell size regulation. Mol Biol Cell 2023; 34:pe3. [PMID: 37339435 PMCID: PMC10398882 DOI: 10.1091/mbc.e22-09-0424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 03/29/2023] [Accepted: 04/28/2023] [Indexed: 06/22/2023] Open
Abstract
Many cells display considerable functional plasticity and depend on the regulation of numerous organelles and macromolecules for their maintenance. In large cells, organelles also need to be carefully distributed to supply the cell with essential resources and regulate intracellular activities. Having multiple copies of the largest eukaryotic organelle, the nucleus, epitomizes the importance of scaling gene products to large cytoplasmic volumes in skeletal muscle fibers. Scaling of intracellular constituents within mammalian muscle fibers is, however, poorly understood, but according to the myonuclear domain hypothesis, a single nucleus supports a finite amount of cytoplasm and is thus postulated to act autonomously, causing the nuclear number to be commensurate with fiber volume. In addition, the orderly peripheral distribution of myonuclei is a hallmark of normal cell physiology, as nuclear mispositioning is associated with impaired muscle function. Because underlying structures of complex cell behaviors are commonly formalized by scaling laws and thus emphasize emerging principles of size regulation, the work presented herein offers more of a unified conceptual platform based on principles from physics, chemistry, geometry, and biology to explore cell size-dependent correlations of the largest mammalian cell by means of scaling.
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Affiliation(s)
- Kenth-Arne Hansson
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, 2624 Lillehammer, Norway
| | - Einar Eftestøl
- Department of Biosciences, University of Oslo, 0371 Oslo, Norway
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20
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Tomasch J, Maleiner B, Hromada C, Szwarc-Hofbauer D, Teuschl-Woller AH. Cyclic Tensile Stress Induces Skeletal Muscle Hypertrophy and Myonuclear Accretion in a 3D Model. Tissue Eng Part A 2023; 29:257-268. [PMID: 36606693 DOI: 10.1089/ten.tea.2022.0182] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Skeletal muscle is highly adaptive to mechanical stress due to its resident stem cells and the pronounced level of myotube plasticity. Herein, we study the adaptation to mechanical stress and its underlying molecular mechanisms in a tissue-engineered skeletal muscle model. We subjected differentiated 3D skeletal muscle-like constructs to cyclic tensile stress using a custom-made bioreactor system, which resulted in immediate activation of stress-related signal transducers (Erk1/2, p38). Cell cycle re-entry, increased proliferation, and onset of myogenesis indicated subsequent myoblast activation. Furthermore, elevated focal adhesion kinase and β-catenin activity in mechanically stressed constructs suggested increased cell adhesion and migration. After 3 days of mechanical stress, gene expression of the fusogenic markers MyoMaker and MyoMixer, myotube diameter, myonuclear accretion, as well as S6 activation, were significantly increased. Our results highlight that we established a promising tool to study sustained adaptation to mechanical stress in healthy, hypertrophic, or regenerating skeletal muscle.
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Affiliation(s)
- Janine Tomasch
- Department Life Science Engineering, University of Applied Sciences Technikum Wien, Vienna, Austria.,The Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Babette Maleiner
- Department Life Science Engineering, University of Applied Sciences Technikum Wien, Vienna, Austria.,The Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Carina Hromada
- Department Life Science Engineering, University of Applied Sciences Technikum Wien, Vienna, Austria.,The Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Dorota Szwarc-Hofbauer
- Department Life Science Engineering, University of Applied Sciences Technikum Wien, Vienna, Austria.,The Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Andreas H Teuschl-Woller
- Department Life Science Engineering, University of Applied Sciences Technikum Wien, Vienna, Austria.,The Austrian Cluster for Tissue Regeneration, Vienna, Austria
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21
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Bagley JR, Denes LT, McCarthy JJ, Wang ET, Murach KA. The myonuclear domain in adult skeletal muscle fibres: past, present and future. J Physiol 2023; 601:723-741. [PMID: 36629254 PMCID: PMC9931674 DOI: 10.1113/jp283658] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 01/06/2023] [Indexed: 01/12/2023] Open
Abstract
Most cells in the body are mononuclear whereas skeletal muscle fibres are uniquely multinuclear. The nuclei of muscle fibres (myonuclei) are usually situated peripherally which complicates the equitable distribution of gene products. Myonuclear abundance can also change under conditions such as hypertrophy and atrophy. Specialised zones in muscle fibres have different functions and thus distinct synthetic demands from myonuclei. The complex structure and regulatory requirements of multinuclear muscle cells understandably led to the hypothesis that myonuclei govern defined 'domains' to maintain homeostasis and facilitate adaptation. The purpose of this review is to provide historical context for the myonuclear domain and evaluate its veracity with respect to mRNA and protein distribution resulting from myonuclear transcription. We synthesise insights from past and current in vitro and in vivo genetically modified models for studying the myonuclear domain under dynamic conditions. We also cover the most contemporary knowledge on mRNA and protein transport in muscle cells. Insights from emerging technologies such as single myonuclear RNA-sequencing further inform our discussion of the myonuclear domain. We broadly conclude: (1) the myonuclear domain can be flexible during muscle fibre growth and atrophy, (2) the mechanisms and role of myonuclear loss and motility deserve further consideration, (3) mRNA in muscle is actively transported via microtubules and locally restricted, but proteins may travel far from a myonucleus of origin and (4) myonuclear transcriptional specialisation extends beyond the classic neuromuscular and myotendinous populations. A deeper understanding of the myonuclear domain in muscle may promote effective therapies for ageing and disease.
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Affiliation(s)
- James R. Bagley
- Muscle Physiology Laboratory, Department of Kinesiology, San Francisco State University, San Francisco, California
| | | | - John J. McCarthy
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Department of Physiology, College of Medicine, University of Kentucky
| | - Eric T. Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, University of Florida, Gainesville, Florida
- Myology Institute, University of Florida
- Genetics Institute, University of Florida
| | - Kevin A. Murach
- Exercise Science Research Center, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, Arkansas
- Cell and Molecular Biology Graduate Program, University of Arkansas
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22
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Flack KD, Vítek L, Fry CS, Stec DE, Hinds TD. Cutting edge concepts: Does bilirubin enhance exercise performance? Front Sports Act Living 2023; 4:1040687. [PMID: 36713945 PMCID: PMC9874874 DOI: 10.3389/fspor.2022.1040687] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 12/19/2022] [Indexed: 01/12/2023] Open
Abstract
Exercise performance is dependent on many factors, such as muscular strength and endurance, cardiovascular capacity, liver health, and metabolic flexibility. Recent studies show that plasma levels of bilirubin, which has classically been viewed as a liver dysfunction biomarker, are elevated by exercise training and that elite athletes may have significantly higher levels. Other studies have shown higher plasma bilirubin levels in athletes and active individuals compared to general, sedentary populations. The reason for these adaptions is unclear, but it could be related to bilirubin's antioxidant properties in response to a large number of reactive oxygen species (ROS) that originates from mitochondria during exercise. However, the mechanisms of these are unknown. Current research has re-defined bilirubin as a metabolic hormone that interacts with nuclear receptors to drive gene transcription, which reduces body weight. Bilirubin has been shown to reduce adiposity and improve the cardiovascular system, which might be related to the adaption of bilirubin increasing during exercise. No studies have directly tested if elevating bilirubin levels can influence athletic performance. However, based on the mechanisms proposed in the present review, this seems plausible and an area to consider for future studies. Here, we discuss the importance of bilirubin and exercise and how the combination might improve metabolic health outcomes and possibly athletic performance.
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Affiliation(s)
- Kyle D. Flack
- Department of Dietetics and Human Nutrition, University of Kentucky, Lexington, KY, United States,Correspondence: Kyle D. Flack Terry D. Hinds
| | - Libor Vítek
- 4th Department of Internal Medicine and Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czechia
| | - Christopher S. Fry
- Department of Athletic Training and Clinical Nutrition, University of Kentucky College of Medicine, Lexington, KY, United States,Center for Muscle Biology, University of Kentucky College of Medicine, Lexington, KY, United States
| | - David E. Stec
- Department of Physiology & Biophysics, Cardiorenal, and Metabolic Diseases Research Center, University of Mississippi Medical Center, Jackson, MS, United States
| | - Terry D. Hinds
- Department of Pharmacology and Nutritional Sciences, University of Kentucky College of Medicine, Lexington, KY, United States,Barnstable Brown Diabetes Center, University of Kentucky College of Medicine, Lexington, KY, United States,Markey Cancer Center, University of Kentucky, Lexington, KY, United States,Correspondence: Kyle D. Flack Terry D. Hinds
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23
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Viggars MR, Owens DJ, Stewart C, Coirault C, Mackey AL, Jarvis JC. PCM1 labeling reveals myonuclear and nuclear dynamics in skeletal muscle across species. Am J Physiol Cell Physiol 2023; 324:C85-C97. [PMID: 36409178 DOI: 10.1152/ajpcell.00285.2022] [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: 11/23/2022]
Abstract
Myonuclei transcriptionally regulate muscle fibers during homeostasis and adaptation to exercise. Their subcellular location and quantity are important when characterizing phenotypes of myopathies, the effect of treatments, and understanding the roles of satellite cells in muscle adaptation and muscle "memory." Difficulties arise in identifying myonuclei due to their proximity to the sarcolemma and closely residing interstitial cell neighbors. We aimed to determine to what extent (pericentriolar material-1) PCM1 is a specific marker of myonuclei in vitro and in vivo. Single isolated myofibers and cross sections from mice and humans were studied from several models including wild-type and Lamin A/C mutant mice after functional overload and damage and recovery in humans following forced eccentric contractions. Fibers were immunolabeled for PCM1, Pax7, and DNA. C2C12 myoblasts were also studied to investigate changes in PCM1 localization during myogenesis. PCM1 was detected at not only the nuclear envelope of myonuclei in mature myofibers and in newly formed myotubes but also centrosomes in proliferating myogenic precursors, which may or may not fuse to join the myofiber syncytium. PCM1 was also detected in nonmyogenic nuclei near the sarcolemma, especially in regenerating areas of the Lmna+/ΔK32 mouse and damaged human muscle. Although PCM1 is not completely specific to myonuclei, the impact that PCM1+ macrophages and interstitial cells have on myonuclei counts would be small in healthy muscle. PCM1 may prove useful as a marker of satellite cell dynamics due to the distinct change in localization during differentiation, revealing satellite cells in their quiescent (PCM1-), proliferating (PCM1+ centrosome), and prefusion states (PCM1+ nuclear envelope).
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Affiliation(s)
- Mark R Viggars
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.,Department of Physiology and Aging, University of Florida, Gainesville, Florida.,Myology Institute, University of Florida, Gainesville, Florida
| | - Daniel J Owens
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.,Sorbonne Université, INSERM, Myology Research Center, Paris, France
| | - Claire Stewart
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | | | - Abigail L Mackey
- Department of Orthopaedic Surgery, Institute of Sports Medicine Copenhagen, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, Center for Healthy Aging, Xlab, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Jonathan C Jarvis
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
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24
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Going nuclear: Molecular adaptations to exercise mediated by myonuclei. SPORTS MEDICINE AND HEALTH SCIENCE 2022; 5:2-9. [PMID: 36994170 PMCID: PMC10040379 DOI: 10.1016/j.smhs.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/23/2022] [Accepted: 11/30/2022] [Indexed: 12/13/2022] Open
Abstract
Muscle fibers are multinucleated, and muscle fiber nuclei (myonuclei) are believed to be post-mitotic and are typically situated near the periphery of the myofiber. Due to the unique organization of muscle fibers and their nuclei, the cellular and molecular mechanisms regulating myofiber homeostasis in unstressed and stressed conditions (e.g., exercise) are unique. A key role myonuclei play in regulating muscle during exercise is gene transcription. Only recently have investigators had the capability to identify molecular changes at high resolution exclusively in myonuclei in response to perturbations in vivo. The purpose of this review is to describe how myonuclei modulate their transcriptome, epigenetic status, mobility and shape, and microRNA expression in response to exercise in vivo. Given the relative paucity of high-fidelity information on myonucleus-specific contributions to exercise adaptation, we identify specific gaps in knowledge and provide perspectives on future directions of research.
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25
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Borowik AK, Davidyan A, Peelor FF, Voloviceva E, Doidge SM, Bubak MP, Mobley CB, McCarthy JJ, Dupont-Versteegden EE, Miller BF. Skeletal Muscle Nuclei in Mice are not Post-mitotic. FUNCTION 2022; 4:zqac059. [PMID: 36569816 PMCID: PMC9772608 DOI: 10.1093/function/zqac059] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/23/2022] Open
Abstract
The skeletal muscle research field generally accepts that nuclei in skeletal muscle fibers (ie, myonuclei) are post-mitotic and unable to proliferate. Because our deuterium oxide (D2O) labeling studies showed DNA synthesis in skeletal muscle tissue, we hypothesized that resident myonuclei can replicate in vivo. To test this hypothesis, we used a mouse model that temporally labeled myonuclei with GFP followed by D2O labeling during normal cage activity, functional overload, and with satellite cell ablation. During normal cage activity, we observed deuterium enrichment into myonuclear DNA in 7 out of 7 plantaris (PLA), 6 out of 6 tibialis anterior (TA), 5 out of 7 gastrocnemius (GAST), and 7 out of 7 quadriceps (QUAD). The average fractional synthesis rates (FSR) of DNA in myonuclei were: 0.0202 ± 0.0093 in PLA, 0.0239 ± 0.0040 in TA, 0.0076 ± 0. 0058 in GAST, and 0.0138 ± 0.0039 in QUAD, while there was no replication in myonuclei from EDL. These FSR values were largely reproduced in the overload and satellite cell ablation conditions, although there were higher synthesis rates in the overloaded PLA muscle. We further provided evidence that myonuclear replication is through endoreplication, which results in polyploidy. These novel findings contradict the dogma that skeletal muscle nuclei are post-mitotic and open potential avenues to harness the intrinsic replicative ability of myonuclei for muscle maintenance and growth.
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Affiliation(s)
- Agnieszka K Borowik
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104, USA
| | - Arik Davidyan
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104, USA
- Department of Biological Sciences, California State University Sacramento, 6000 J Street, Sacramento, CA, 95819, USA
| | - Frederick F Peelor
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104, USA
| | - Evelina Voloviceva
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104, USA
| | - Stephen M Doidge
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104, USA
| | - Matthew P Bubak
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104, USA
| | | | - John J McCarthy
- Center for Muscle Biology, University of Kentucky, Lexington, KY 40506, USA
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, 40506, USA
| | - Esther E Dupont-Versteegden
- Center for Muscle Biology, University of Kentucky, Lexington, KY 40506, USA
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, 40506, USA
- Department of Physical Therapy, College of Health Sciences, University of Kentucky, 900 S Limestone, Lexington, KY 40536, USA
| | - Benjamin F Miller
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104, USA
- Oklahoma City VA Medical Center, 921 NE 13th St, Oklahoma City, OK 73104, USA
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26
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Rader EP, Baker BA. Elevated muscle mass accompanied by transcriptional and nuclear alterations several months following cessation of resistance-type training in rats. Physiol Rep 2022; 10:e15476. [PMID: 36259109 PMCID: PMC9579736 DOI: 10.14814/phy2.15476] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/31/2022] [Accepted: 09/05/2022] [Indexed: 06/16/2023] Open
Abstract
Rodent studies investigating long-term effects following termination of hypertrophy-inducing loading have predominantly involved exposures such as synergist ablation and weighted wheel running or ladder climbing. This research yielded a spectrum of results regarding the extent of detraining in terms of muscle mass and myonuclei number. The studies were also limited in their lack of sensitive performance measures and indirect relatedness to resistance training. Our research group developed and validated a relevant rat model of resistance-type training that induces increased muscle mass and performance. The aim of the present study was to determine to what extent these features persist 3 months following the termination of this training. While performance returned to baseline, muscle mass remained elevated by 17% and a shift in distribution to larger muscle fibers persisted. A 16% greater total RNA and heightened mRNA levels of ribosomal protein S6 kinases implicated preserved transcriptional output and ribosomal content. Remodeling of muscle fiber nuclei was consistent with these findings - increased nuclear number and a distribution shift to a more circular nuclear shape. These findings indicate that muscle mass detrains at a slower rate than performance and implicates multiple forms of myonuclear remodeling in muscle memory.
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Affiliation(s)
- Erik P. Rader
- Centers for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
| | - Brent A. Baker
- Centers for Disease Control and PreventionNational Institute for Occupational Safety and HealthMorgantownWest VirginiaUSA
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27
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Hung YL, Sato A, Takino Y, Ishigami A, Machida S. Influence of oestrogen on satellite cells and myonuclear domain size in skeletal muscles following resistance exercise. J Cachexia Sarcopenia Muscle 2022; 13:2525-2536. [PMID: 35818664 PMCID: PMC9530499 DOI: 10.1002/jcsm.13031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 04/02/2022] [Accepted: 05/12/2022] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Oestrogen deficiency reduces skeletal muscle mass and force generation in postmenopausal women. Muscle mass is maintained by satellite cells, which are regulated by oestrogen. Although oestrogen therapy enhances muscle hypertrophy induced by resistance training in postmenopausal women, the molecular mechanism is unclear. METHODS Adult female rats (10 weeks old) were divided into six groups: sham sedentary (Sham-Sed), sham climbing training (Sham-CT), ovariectomy sedentary (OVX-Sed), ovariectomy climbing training (OVX-CT), ovariectomy plus oestrogen treatment sedentary (OVX+E-Sed), and ovariectomy plus oestrogen treatment climbing training (OVX+E-CT). At 8 weeks after ovariectomy, rats in the training group were trained (one session every 3 days for 8 weeks) to climb a ladder while bearing a load. Oestrogen treatment involved subcutaneous insertion of a 17β-oestradiol pellet. After 8 weeks, the flexor hallucis longus muscle was collected and analysed. RESULTS Following climbing training, the flexor hallucis longus muscle mass and muscle-to-body weight ratios were dramatically increased by training (main effect of training, P < 0.01); the OVX+E-CT group showed the highest values (main effect of group, P < 0.01). The cross-sectional area of all muscle fibre types was increased by training (main effect of training, P < 0.01). Particularly, the cross-sectional area of MHC IIa in the OVX+E-CT group was significantly larger than that in the Sham-CT and OVX-CT groups. Satellite cell numbers were increased in all training groups (main effect of training, P < 0.05), and the myonuclear number was increased by training (main effect of training, P < 0.01), but there was no main group effect. The myonuclear domain size of all muscle fibre types and MHC IIa was increased in all training groups (main effect of training, P < 0.01) and showed a main group effect (P < 0.01). The myonuclear domain sizes of all muscle fibre types and MHC IIa in the OVX+E-CT group were significantly larger than those in the Sham-CT and OVX-CT groups. The total RNA contents revealed main effects of training and the group (P < 0.01); the OVX+E-CT group showed the highest contents (main effect of group, P < 0.01). The mRNA and protein levels of rpS6 were increased in the OVX+E-Sed and CT groups (main effects of group, P < 0.05). Particularly, the 28S ribosomal RNA content in OVX+E-Sed group was significantly higher than that in the OVX-Sed group. CONCLUSIONS Oestrogen enhanced the resistance training-induced increase in myonuclear domain size but did not affect satellite cells and ribosome biogenesis.
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Affiliation(s)
- Yung-Li Hung
- Institute of Health and Sports & Medicine, Juntendo University, Chiba, Japan
| | - Ayami Sato
- Molecular Regulation of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Yuka Takino
- Molecular Regulation of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Akihito Ishigami
- Molecular Regulation of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Shuichi Machida
- Institute of Health and Sports & Medicine, Juntendo University, Chiba, Japan.,Graduate School of Health and Sports Science, Juntendo University, Chiba, Japan
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28
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Brightwell CR, Latham CM, Thomas NT, Keeble AR, Murach KA, Fry CS. A glitch in the matrix: the pivotal role for extracellular matrix remodeling during muscle hypertrophy. Am J Physiol Cell Physiol 2022; 323:C763-C771. [PMID: 35876284 PMCID: PMC9448331 DOI: 10.1152/ajpcell.00200.2022] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/21/2022] [Accepted: 07/21/2022] [Indexed: 01/18/2023]
Abstract
Multinuclear muscle fibers are the most voluminous cells in skeletal muscle and the primary drivers of growth in response to loading. Outside the muscle fiber, however, is a diversity of mononuclear cell types that reside in the extracellular matrix (ECM). These muscle-resident cells are exercise-responsive and produce the scaffolding for successful myofibrillar growth. Without proper remodeling and maintenance of this ECM scaffolding, the ability to mount an appropriate response to resistance training in adult muscles is severely hindered. Complex cellular choreography takes place in muscles following a loading stimulus. These interactions have been recently revealed by single-cell explorations into muscle adaptation with loading. The intricate ballet of ECM remodeling involves collagen production from fibrogenic cells and ECM modifying signals initiated by satellite cells, immune cells, and the muscle fibers themselves. The acellular collagen-rich ECM is also a mechanical signal-transducer and rich repository of growth factors that may directly influence muscle fiber hypertrophy once liberated. Collectively, high levels of collagen expression, deposition, and turnover characterize a well-trained muscle phenotype. The purpose of this review is to highlight the most recent evidence for how the ECM and its cellular components affect loading-induced muscle hypertrophy. We also address how the muscle fiber may directly take part in ECM remodeling, and whether ECM dynamics are rate limiting for muscle fiber growth.
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Affiliation(s)
- Camille R Brightwell
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Department of Athletic Training and Clinical Nutrition, College of Health Sciences, University of Kentucky, Lexington, Kentucky
| | - Christine M Latham
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Department of Athletic Training and Clinical Nutrition, College of Health Sciences, University of Kentucky, Lexington, Kentucky
| | - Nicholas T Thomas
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Department of Athletic Training and Clinical Nutrition, College of Health Sciences, University of Kentucky, Lexington, Kentucky
| | - Alexander R Keeble
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Department of Athletic Training and Clinical Nutrition, College of Health Sciences, University of Kentucky, Lexington, Kentucky
| | - Kevin A Murach
- Department of Health, Human Performance, and Recreation, Molecular Muscle Mass Regulation Laboratory, Exercise Science Research Center, University of Arkansas, Fayetteville, Arkansas
- Cell and Molecular Biology Graduate Program, University of Arkansas, Fayetteville, Arkansas
| | - Christopher S Fry
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Department of Athletic Training and Clinical Nutrition, College of Health Sciences, University of Kentucky, Lexington, Kentucky
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29
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Abstract
Despite the evolutionary loss of tissue regenerative potential, robust skeletal muscle repair processes are largely retained even in higher vertebrates. In mammals, the skeletal muscle regeneration program is driven by resident stem cells termed satellite cells, guided by the coordinated activity of multiple intrinsic and extrinsic factors and other cell types. A thorough understanding of muscle repair mechanisms is crucial not only for combating skeletal myopathies, but for its prospective aid in devising therapeutic strategies to endow regenerative potential on otherwise regeneration-deficient organs. In this review, we discuss skeletal muscle regeneration from an evolutionary perspective, summarize the current knowledge of cellular and molecular mechanisms, and highlight novel paradigms of muscle repair revealed by explorations of the recent decade.
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Affiliation(s)
- Sajedah M Hindi
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA
| | - Douglas P Millay
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229, USA
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30
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Barshick MR, Gonzalez ML, Busse NI, Helsel PJ, Johnson SE. The initial delay to mitotic activity in primary cultures of equine satellite cells is reduced by combinations of growth factors. J Anim Sci 2022; 100:6652326. [PMID: 35908788 PMCID: PMC9339324 DOI: 10.1093/jas/skac140] [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: 03/22/2022] [Accepted: 04/11/2022] [Indexed: 11/12/2022] Open
Abstract
Satellite cell (SC) activation is defined as the time frame during which the stem cell becomes poised to reenter G1 of the cell cycle. The growth factors and events leading to full mitotic activation in equine SCs remain largely unknown. Insulin-like growth factor I (IGF-I), hepatocyte growth factor (HGF), and fibroblast growth factor 2 (FGF2) are sequentially transcribed during the muscle repair and recovery period following strenuous exercise in adult horses. Expression of IGF-I occurs within 24 h of the postexercise recovery period suggesting it may affect early SC actions. As a first step, gluteus medius muscle cryosections from adult horses (n = 9) were examined for the presence of central nuclei (CN), a marker of SC addition to the fiber. Results demonstrate few CN fibers prior to exercise with a 3-fold increase (P = 0.05) 24 h postexercise. Cultures of SC (n = 4 isolates) were treated with 100 ng/mL IGF-I for varying times prior to measurement of myogenic events. Results demonstrate that IGF-I does not affect the initial lag period, proliferation, or subsequent differentiation of equine SC in vitro (P > 0.05). However, media containing a combination of IGF-I and 10 ng/mL FGF2 and 25 ng/mL HGF hastens (P < 0.05) the time to S-phase entry in fresh isolates of SCs. Media supplementation with optimal concentrations of FGF2, HGF, or a combination of HGF and FGF2 suppresses (P < 0.05) the percentage of myogenin immunopositive SCs to levels below that found in control- or IGF-I-treated SCs. These results provide new insight into the combinatorial roles growth factors play during equine SC myogenesis.
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Affiliation(s)
- Madison R Barshick
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Madison L Gonzalez
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Nicolas I Busse
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Patricia J Helsel
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Sally E Johnson
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
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31
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Shimizu J, Kawano F. Exercise-induced H3K27me3 facilitates the adaptation of skeletal muscle to exercise in mice. J Physiol 2022; 600:3331-3353. [PMID: 35666835 DOI: 10.1113/jp282917] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 05/30/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Exercise mediates H3K27me3 at transcriptionally upregulated loci in skeletal muscle, although the role of H3K27me3 in the adaptation of skeletal muscle to exercise training is unclear. Chromatin immunoprecipitation followed by sequencing analysis demonstrated that H3K27me3, as well as H3K4me3 modifications, is the hallmark of sites showing higher responses to acute exercise. GSK343, a selective inhibitor of the enhancer of zeste homologue 2 (EZH2), enhanced the gene responses to a single bout of exercise and accelerated the adaptive changes during exercise training in association with myonuclear H3K27me3 accumulation. Administration of valemetostat, an EZH1/2 dual inhibitor, repressed myonuclear H3K27me3 accumulation during training and caused the failure in adaptive changes. Exercise-induced H3K27me3 may play a key role in inducing exercise-related effects in the skeletal muscle. ABSTRACT Histone H3 trimethylation at lysine 27 (H3K27me3) is known to act as a transcriptionally repressive histone modification via heterochromatin formation. However, in skeletal muscle, it was also reported that H3K27me3 was enriched at the sites transcriptionally activated by exercise, although the role of H3K27me3 in the adaptation to exercise is unknown. In this study, we first determined the genome-wide enrichment of RNA polymerase II and histone H3 trimethylation at lysine 4 (H3K4me3) and H3K27me3 using chromatin immunoprecipitation followed by sequencing analysis in mouse tibialis anterior muscle. The loci that were transcriptionally upregulated by a single bout of running exercise were marked by both H3K27me3 and H3K4me3, which also correlated with the distribution of RNA polymerase II. The genes that were not responsive to exercise exhibited high H3K4me3 occupancy, similar to the upregulated genes but with fewer H3K27me3. Next, we tested the effects of H3K27 methyltransferase, an enhancer of zeste homologue (EZH) 2-specific inhibitor GSK343. GSK343 administration unexpectedly enhanced the H3K27me3 occupancy at the target loci, leading to the upregulation of gene responses to acute exercise. GSK343 administration also facilitated the phenotypic transformation from IIb to IIa fibres and the upregulation of AMPK phosphorylation and HSP70, PDK4, PGC-1α, and MuRF1 levels. Furthermore, in contrast to the accelerated adaptation to exercise by GSK343, EZH1/2 dual inhibitor valemetostat administration caused the failure in the changes of the aforementioned parameters after exercise training. These results indicate that exercise-induced H3K27me3 plays a key role in inducing exercise-related effects in the skeletal muscle. Abstract figure legend The loci upregulated in response to exercise are characterized by a bivalent modification with histone H3 trimethylation at lysine 27 (H3K27me3) and lysine 4 (H3K4me3) in mouse skeletal muscle. Acute exercise further stimulates both H3K27me3 and H3K4me3 at these loci associated with the upregulation of gene transcription. Lysine methyltransferase EZH2-specific inhibitor GSK343 administration increased H3K27me3 and H3K4me3 occupancies at the target loci after a single bout of exercise. Chronic treatment of GSK343 during exercise training more upregulated H3K27me3 in muscle fibres. In addition, it increased the number of muscle fibres expressing type IIa myosin heavy chain (MyHC) and enhanced the adaptive changes in the related protein levels. In contrast, administration of valemetostat, an EZH1/2 dual inhibitor, decreased H3K27me3 and H3K4me3 occupancies after acute exercise and caused the failure in the exercise-induced effects after training. It was also suggested that EZH1 acted as a modifier of exercise-induced H3K27me3 in skeletal muscle. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Junya Shimizu
- Graduate School of Health Sciences, Matsumoto University, 2095-1 Niimura, Matsumoto City, Nagano, 390-1295, Japan
| | - Fuminori Kawano
- Graduate School of Health Sciences, Matsumoto University, 2095-1 Niimura, Matsumoto City, Nagano, 390-1295, Japan
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Bachman JF, Chakkalakal JV. Insights into muscle stem cell dynamics during postnatal development. FEBS J 2022; 289:2710-2722. [PMID: 33811430 PMCID: PMC9947813 DOI: 10.1111/febs.15856] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/17/2021] [Accepted: 03/31/2021] [Indexed: 12/11/2022]
Abstract
During development, resident stem cell populations contribute to the growth and maturation of tissue and organs. In skeletal muscle, muscle stem cells, or satellite cells (SCs), are responsible for the maturation of postnatal myofibers. However, the role SCs play in later stages of postnatal growth, and thus, when they enter a mature quiescent state is controversial. Here, we discuss the current literature regarding the role SCs play in all stages of postnatal growth, from birth to puberty onset to young adulthood. We additionally highlight the implications of SC loss or dysfunction during developmental stages, both in the context of experimental paradigms and disease settings.
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Affiliation(s)
- John F Bachman
- Department of Pathology and Laboratory Medicine, Cell Biology of Disease Graduate Program, University of Rochester Medical Center, Rochester NY, United States.,Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester NY, United States
| | - Joe V Chakkalakal
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester NY, United States.,Department of Biomedical Engineering, University of Rochester, Rochester NY, United States.,Wilmot Cancer Institute, University of Rochester Medical Center, Rochester NY, United States.,Stem Cell and Regenerative Medicine Institute, and The Rochester Aging Research Center, University of Rochester Medical Center, Rochester NY, United States.,Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester NY, United States
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33
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Ato S, Fukada SI, Kokubo H, Ogasawara R. Implication of satellite cell behaviors in capillary growth via VEGF expression-independent mechanism in response to mechanical loading in HeyL-null mice. Am J Physiol Cell Physiol 2022; 322:C275-C282. [PMID: 35020502 DOI: 10.1152/ajpcell.00343.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 01/04/2022] [Accepted: 01/04/2022] [Indexed: 11/22/2022]
Abstract
Angiogenesis and muscle satellite cell (SC)-mediated myonuclear accretion are considered essential for the robust response of contraction-induced muscle hypertrophy. Moreover, both myonucleus and SCs are physically adjacent to capillaries and are the major sites for the expression of proangiogenic factors, such as VEGF, in the skeletal muscle. Thus, events involving the addition of new myonuclei via activation of SCs may play an important role in angiogenesis during muscle hypertrophy. However, the relevance among myonuclei number, capillary supply, and angiogenesis factor is not demonstrated. The Notch effector HeyL is specifically expressed in SCs in the skeletal muscle and is crucial for SC proliferation by inhibiting MyoD in overload-induced muscle hypertrophy. Here, we tested whether the addition of new myonuclei by SC in overloaded muscle is associated with angiogenic adaptation by reanalyzing skeletal muscle from HeyL-knockout (KO) mice, which show blunted responses of SC proliferation, myonucleus addition, and overload-induced muscle hypertrophy. Reanalysis confirmed blunted SC proliferation and myonuclear accretion in the plantaris muscle of HeyL-KO mice 9 wk after synergist ablation. Interestingly, the increase in capillary-to-fiber ratio observed in wild-type (WT) mice was impaired in HeyL-KO mice. In both WT and HeyL-KO mice, the expression of VEGFA and VEGFB was similarly increased in response to overload. In addition, the expression pattern of TSP-1, a negative regulator of angiogenesis, was also not changed between WT and HeyL-KO mice. Collectively, these results suggest that SCs activation-myonuclear accretion plays a crucial role in angiogenesis during overload-induced muscle hypertrophy via independent of angiogenesis regulators.
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Affiliation(s)
- Satoru Ato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - So-Ichiro Fukada
- Project for Muscle Stem Cell Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan
| | - Hiroki Kokubo
- Department of Cardiovascular Physiology and Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
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Viggars MR, Wen Y, Peterson CA, Jarvis JC. Automated cross-sectional analysis of trained, severely atrophied and recovering rat skeletal muscles using MyoVision 2.0. J Appl Physiol (1985) 2022; 132:593-610. [PMID: 35050795 DOI: 10.1152/japplphysiol.00491.2021] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The number of myonuclei within a muscle fiber is an important factor in muscle growth, but its regulation during muscle adaptation is not well understood. We aimed to elucidate the timecourse of myonuclear dynamics during endurance training, loaded and concentric resistance training, and nerve silencing-induced disuse atrophy with subsequent recovery. We modified tibialis anterior muscle activity in free-living rats with electrical stimulation from implantable pulse generators, or with implantable osmotic pumps delivering tetrodotoxin (TTX) to silence the motor nerve without transection. We used the updated, automated software MyoVision to measure fiber type-specific responses in whole tibialis anterior cross-sections (~8000 fibers each). Seven days of continuous low frequency stimulation (CLFS) reduced muscle mass (-12%), increased slower myosin isoforms and reduced IIX/IIB fibers (-32%) and substantially increased myonuclei especially in IIX/IIB fibers (55.5%). High load resistance training (Spillover), produced greater hypertrophy (~16%) in muscle mass and fiber cross-sectional area (CSA) than low load resistance training (concentric, ~6%) and was associated with myonuclear addition in all fiber types (35-46%). TTX-induced nerve silencing resulted in progressive loss in muscle mass, fiber CSA, and myonuclei per fiber cross-section (-50.7%, -53.7%, -40.7%, respectively at 14 days). Myonuclear loss occurred in a fiber type-independent manner, but subsequent recovery during voluntary habitual activity suggested that type IIX/IIB fibers contained more new myonuclei during recovery from severe atrophy. This study demonstrates the power and accuracy provided by the updated MyoVision software and introduces new models for studying myonuclear dynamics in training, detraining, retraining, repeated disuse, and recovery.
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Affiliation(s)
- Mark Robert Viggars
- Research Institute for Sport & Exercise Sciences, grid.4425.7Liverpool John Moores University, Liverpool, United Kingdom.,Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, United States.,Myology Institute, University of Florida, Gainesville, Florida, United States
| | - Yuan Wen
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States.,Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, United States.,MyoAnalytics, LLC, Lexington, Kentucky, United States
| | - Charlotte A Peterson
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States.,Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, United States
| | - Jonathan C Jarvis
- Research Institute for Sport & Exercise Sciences, grid.4425.7Liverpool John Moores University, Liverpool, United Kingdom
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35
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Yoon JH, Lee SM, Lee Y, Kim MJ, Yang JW, Choi JY, Kwak JY, Lee KP, Yang YR, Kwon KS. Alverine citrate promotes myogenic differentiation and ameliorates muscle atrophy. Biochem Biophys Res Commun 2022; 586:157-162. [PMID: 34847441 DOI: 10.1016/j.bbrc.2021.11.076] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 11/18/2021] [Indexed: 11/25/2022]
Abstract
Sarcopenia is the age-related loss of muscle mass and function and no pharmacological medication has been approved for its treatment. We established an atrogin-1/MAFbx promoter assay to find drug candidates that inhibit myotube atrophy. Alverine citrate (AC) was identified using high-throughput screening of an existing drug library. AC is an established medicine for stomach and intestinal spasms. AC treatment increased myotube diameter and inhibited atrophy signals induced by either C26-conditioned medium or dexamethasone in cultured C2C12 myoblasts. AC also enhanced myoblast fusion through the upregulation of fusion-related genes during C2C12 myoblast differentiation. Oral administration of AC improves muscle mass and physical performance in aged mice, as well as hindlimb-disused mice. Taken together, our data suggest that AC may be a novel therapeutic candidate for improving muscle weakness, including sarcopenia.
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Affiliation(s)
- Jong Hyeon Yoon
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea; Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, Republic of Korea
| | - Seung-Min Lee
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | | | - Min Ju Kim
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea; Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, Republic of Korea
| | - Jae Won Yang
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea; Department of Biomolecular Science, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, Republic of Korea
| | - Jeong Yi Choi
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Ju Yeon Kwak
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Kwang-Pyo Lee
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea; Department of Biomolecular Science, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, Republic of Korea
| | - Yong Ryoul Yang
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Ki-Sun Kwon
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea; Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, Republic of Korea; Aventi Inc., Daejeon, Republic of Korea.
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36
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Emmert ME, Aggarwal P, Shay-Winkler K, Lee SJ, Goh Q, Cornwall R. Sex-specific role of myostatin signaling in neonatal muscle growth, denervation atrophy, and neuromuscular contractures. eLife 2022; 11:81121. [PMID: 36314781 PMCID: PMC9873256 DOI: 10.7554/elife.81121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 10/31/2022] [Indexed: 01/27/2023] Open
Abstract
Neonatal brachial plexus injury (NBPI) causes disabling and incurable muscle contractures that result from impaired longitudinal growth of denervated muscles. This deficit in muscle growth is driven by increased proteasome-mediated protein degradation, suggesting a dysregulation of muscle proteostasis. The myostatin (MSTN) pathway, a prominent muscle-specific regulator of proteostasis, is a putative signaling mechanism by which neonatal denervation could impair longitudinal muscle growth, and thus a potential target to prevent NBPI-induced contractures. Through a mouse model of NBPI, our present study revealed that pharmacologic inhibition of MSTN signaling induces hypertrophy, restores longitudinal growth, and prevents contractures in denervated muscles of female but not male mice, despite inducing hypertrophy of normally innervated muscles in both sexes. Additionally, the MSTN-dependent impairment of longitudinal muscle growth after NBPI in female mice is associated with perturbation of 20S proteasome activity, but not through alterations in canonical MSTN signaling pathways. These findings reveal a sex dimorphism in the regulation of neonatal longitudinal muscle growth and contractures, thereby providing insights into contracture pathophysiology, identifying a potential muscle-specific therapeutic target for contracture prevention, and underscoring the importance of sex as a biological variable in the pathophysiology of neuromuscular disorders.
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Affiliation(s)
- Marianne E Emmert
- Department of Medical Sciences, University of Cincinnati College of MedicineCincinnatiUnited States
| | - Parul Aggarwal
- Division of Orthopaedic Surgery, Cincinnati Children’s Hospital Medical CenterCincinnatiUnited States
| | - Kritton Shay-Winkler
- Division of Orthopaedic Surgery, Cincinnati Children’s Hospital Medical CenterCincinnatiUnited States
| | - Se-Jin Lee
- The Jackson LaboratoryFarmingtonUnited States,Department of Genetics and Genome Sciences, University of Connecticut School of MedicineFarmingtonUnited States
| | - Qingnian Goh
- Division of Orthopaedic Surgery, Cincinnati Children’s Hospital Medical CenterCincinnatiUnited States,Department of Orthopaedic Surgery, University of Cincinnati College of MedicineCincinnatiUnited States
| | - Roger Cornwall
- Division of Orthopaedic Surgery, Cincinnati Children’s Hospital Medical CenterCincinnatiUnited States,Department of Orthopaedic Surgery, University of Cincinnati College of MedicineCincinnatiUnited States,Division of Developmental Biology, Cincinnati Children’s Hospital Medical CenterCincinnatiUnited States,Department of Pediatrics, University of Cincinnati College of MedicineCincinnatiUnited States
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37
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Murach KA, Dungan CM, von Walden F, Wen Y. Epigenetic evidence for distinct contributions of resident and acquired myonuclei during long-term exercise adaptation using timed in vivo myonuclear labeling. Am J Physiol Cell Physiol 2022; 322:C86-C93. [PMID: 34817266 PMCID: PMC8765804 DOI: 10.1152/ajpcell.00358.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Muscle fibers are syncytial postmitotic cells that can acquire exogenous nuclei from resident muscle stem cells, called satellite cells. Myonuclei are added to muscle fibers by satellite cells during conditions such as load-induced hypertrophy. It is difficult to dissect the molecular contributions of resident versus satellite cell-derived myonuclei during adaptation due to the complexity of labeling distinct nuclear populations in multinuclear cells without label transference between nuclei. To sidestep this barrier, we used a genetic mouse model where myonuclear DNA can be specifically and stably labeled via nonconstitutive H2B-GFP at any point in the lifespan. Resident myonuclei (Mn) were GFP-tagged in vivo before 8 wk of progressive weighted wheel running (PoWeR) in adult mice (>4-mo-old). Resident + satellite cell-derived myonuclei (Mn+SC Mn) were labeled at the end of PoWeR in a separate cohort. Following myonuclear isolation, promoter DNA methylation profiles acquired with low-input reduced representation bisulfite sequencing (RRBS) were compared to deduce epigenetic contributions of satellite cell-derived myonuclei during adaptation. Resident myonuclear DNA has hypomethylated promoters in genes related to protein turnover, whereas the addition of satellite cell-derived myonuclei shifts myonuclear methylation profiles to favor transcription factor regulation and cell-cell signaling. By comparing myonucleus-specific methylation profiling to previously published single-nucleus transcriptional analysis in the absence (Mn) versus the presence of satellite cells (Mn+SC Mn) with PoWeR, we provide evidence that satellite cell-derived myonuclei may preferentially supply specific ribosomal proteins to growing myofibers and retain an epigenetic "memory" of prior stem cell identity. These data offer insights on distinct epigenetic myonuclear characteristics and contributions during adult muscle growth.
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Affiliation(s)
- Kevin A. Murach
- 1Molecular Muscle Mass Regulation Laboratory, Exercise Science Research Center, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, Arkansas,2Cell and Molecular Biology Program, University of Arkansas, Fayetteville, Arkansas,3The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | - Cory M. Dungan
- 3The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky,4Department of Physical Therapy, College of Health Sciences, University of Kentucky, Lexington, Kentucky
| | - Ferdinand von Walden
- 5Department of Women’s and Children’s Health, Karolinska Institute, Stockholm, Sweden
| | - Yuan Wen
- 3The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky,6Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky,7Myoanalytics, LLC, Lexington, Kentucky
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Fukada SI, Ito N. Regulation of muscle hypertrophy: Involvement of the Akt-independent pathway and satellite cells in muscle hypertrophy. Exp Cell Res 2021; 409:112907. [PMID: 34793776 DOI: 10.1016/j.yexcr.2021.112907] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 10/04/2021] [Accepted: 10/29/2021] [Indexed: 12/25/2022]
Abstract
Skeletal muscles are composed of multinuclear cells called myofibers and have unique abilities, one of which is plasticity. In response to the mechanical load induced by physical activity, skeletal muscle exerts several local adaptations, including an increase in myofiber size and myonuclear number, known as muscle hypertrophy. Protein synthesis and muscle satellite cells (MuSCs) are mainly responsible for these adaptations. However, the upstream signaling pathways that promote protein synthesis remain controversial. Further, the necessity of MuSCs in muscle hypertrophy is also a highly debated issue. In this review, we summarized the insulin-like growth factor 1 (IGF-1)/Akt-independent activation of mammalian target of rapamycin (mTOR) signaling in muscle hypertrophy and the involvement of mTOR signaling in age-related loss of skeletal muscle function and mass and in sarcopenia. The roles and behaviors of MuSCs, characteristics of new myonuclei in muscle hypertrophy, and their relevance to sarcopenia have also been updated in this review.
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Affiliation(s)
- So-Ichiro Fukada
- Project for Muscle Stem Cell Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan.
| | - Naoki Ito
- Laboratory of Molecular Life Science, Institute of Biomedical Research and Innovation (IBRI), Foundation for Biomedical Research and Innovation at Kobe (FBRI), Kobe, Japan
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39
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Rahmati M, Rashno A. Automated image segmentation method to analyse skeletal muscle cross section in exercise-induced regenerating myofibers. Sci Rep 2021; 11:21327. [PMID: 34716401 PMCID: PMC8556272 DOI: 10.1038/s41598-021-00886-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/14/2021] [Indexed: 02/07/2023] Open
Abstract
Skeletal muscle is an adaptive tissue with the ability to regenerate in response to exercise training. Cross-sectional area (CSA) quantification, as a main parameter to assess muscle regeneration capability, is highly tedious and time-consuming, necessitating an accurate and automated approach to analysis. Although several excellent programs are available to automate analysis of muscle histology, they fail to efficiently and accurately measure CSA in regenerating myofibers in response to exercise training. Here, we have developed a novel fully-automated image segmentation method based on neutrosophic set algorithms to analyse whole skeletal muscle cross sections in exercise-induced regenerating myofibers, referred as MyoView, designed to obtain accurate fiber size and distribution measurements. MyoView provides relatively efficient, accurate, and reliable measurements for CSA quantification and detecting different myofibers, myonuclei and satellite cells in response to the post-exercise regenerating process. We showed that MyoView is comparable with manual quantification. We also showed that MyoView is more accurate and efficient to measure CSA in post-exercise regenerating myofibers as compared with Open-CSAM, MuscleJ, SMASH and MyoVision. Furthermore, we demonstrated that to obtain an accurate CSA quantification of exercise-induced regenerating myofibers, whole muscle cross-section analysis is an essential part, especially for the measurement of different fiber-types. We present MyoView as a new tool to quantify CSA, myonuclei and satellite cells in skeletal muscle from any experimental condition including exercise-induced regenerating myofibers.
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Affiliation(s)
- Masoud Rahmati
- Department of Exercise Physiology, Faculty of Literature and Human Sciences, Lorestan University, Khoramabad, Iran.
| | - Abdolreza Rashno
- Department of Computer Engineering, Lorestan University, Khorramabad, Iran
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40
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Fu S, Lin X, Yin L, Wang X. Androgen receptor regulates the proliferation of myoblasts under appropriate or excessive stretch through IGF-1 receptor mediated p38 and ERK1/2 pathways. Nutr Metab (Lond) 2021; 18:85. [PMID: 34526063 PMCID: PMC8444398 DOI: 10.1186/s12986-021-00610-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 08/21/2021] [Indexed: 12/23/2022] Open
Abstract
Background Androgen receptor (AR) exerts important roles in exercise-induced alterations of muscle mass, in which the proliferation and differentiation of satellite cells or myoblasts are crucial. Our previous study in C2C12 myoblasts demonstrated that 15% (mimic appropriate exercise) and 20% (mimic excessive exercise) stretches promoted and inhibited the proliferation respectively; and AR played a crucial role in 15% stretch-induced pro-proliferation through IGF-1-modulated PI3K/Akt, p38 and ERK1/2 pathways, but AR’s role in stretches-modulated proliferation of general myoblasts, especially 20% stretch, remains unclear, and the mechanisms need to be further clarified. Methods Firstly, the discrepancy in proliferation and the above indicators between L6 (without AR) and C2C12 (with AR) myoblasts were compared under 15% or 20% stretch. Then the influences of transfection AR or exogenous IGF-1 treatment on proliferation and these indicators were detected in stretched L6 myoblasts. Results (1) Under un-stretched state, the proliferation of L6 was slower than C2C12 cells. Furthermore, AR knockdown in C2C12 myoblasts repressed, while AR overexpression in L6 myoblasts promoted the proliferation. (2) 15% stretch-induced increases in the proliferation and activities of p38 and ERK1/2 were lower in L6 than C2C12 cells; AR overexpression enhanced the proliferation of 15% stretched L6 cells accompanied with the increases of p38 and ERK1/2 activities. (3) 20% stretch-induced anti-proliferation and inhibition of p38 activity were severer in L6 than C2C12 myoblasts; AR overexpression reversed the anti-proliferation of 20% stretch and enhanced p38 activity in L6 myoblasts. (4) In stretched L6 myoblasts, AR overexpression increased IGF-1R level despite no detectable IGF-1; and recombinant IGF-1 increased the proliferation, the level of IGF-1R, and the activities of p38 and ERK1/2 in 15% stretched L6 myoblasts. Conclusions The study demonstrated AR's crucial roles in stretches-regulated proliferation of myoblasts, and increased AR fulfilled 15% stretch's pro-proliferation via activating IGF-1R- p38 and ERK1/2 pathways while decreased AR achieved 20% stretch's anti-proliferation via inhibiting IGF-1R- p38 pathway, which is useful to understand in depth the role and mechanisms of AR in appropriate exercise increasing while excessive exercise decreasing muscle mass.
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Affiliation(s)
- Shaoting Fu
- Department of Exercise Physiology, School of Kinesiology, Shanghai University of Sport, 188 Hengren Road, Yangpu District, Shanghai, 200438, China.,Department of Kinesiology, College of Physical Education, Shanghai Normal University, Shanghai, 200234, China
| | - Xiaojing Lin
- Department of Exercise Physiology, School of Kinesiology, Shanghai University of Sport, 188 Hengren Road, Yangpu District, Shanghai, 200438, China
| | - Lijun Yin
- Department of Exercise Physiology, School of Kinesiology, Shanghai University of Sport, 188 Hengren Road, Yangpu District, Shanghai, 200438, China
| | - Xiaohui Wang
- Department of Exercise Physiology, School of Kinesiology, Shanghai University of Sport, 188 Hengren Road, Yangpu District, Shanghai, 200438, China.
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41
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Murach KA, Fry CS, Dupont-Versteegden EE, McCarthy JJ, Peterson CA. Fusion and beyond: Satellite cell contributions to loading-induced skeletal muscle adaptation. FASEB J 2021; 35:e21893. [PMID: 34480776 PMCID: PMC9293230 DOI: 10.1096/fj.202101096r] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 08/13/2021] [Accepted: 08/17/2021] [Indexed: 12/14/2022]
Abstract
Satellite cells support adult skeletal muscle fiber adaptations to loading in numerous ways. The fusion of satellite cells, driven by cell-autonomous and/or extrinsic factors, contributes new myonuclei to muscle fibers, associates with load-induced hypertrophy, and may support focal membrane damage repair and long-term myonuclear transcriptional output. Recent studies have also revealed that satellite cells communicate within their niche to mediate muscle remodeling in response to resistance exercise, regulating the activity of numerous cell types through various mechanisms such as secretory signaling and cell-cell contact. Muscular adaptation to resistance and endurance activity can be initiated and sustained for a period of time in the absence of satellite cells, but satellite cell participation is ultimately required to achieve full adaptive potential, be it growth, function, or proprioceptive coordination. While significant progress has been made in understanding the roles of satellite cells in adult muscle over the last few decades, many conclusions have been extrapolated from regeneration studies. This review highlights our current understanding of satellite cell behavior and contributions to adaptation outside of regeneration in adult muscle, as well as the roles of satellite cells beyond fusion and myonuclear accretion, which are gaining broader recognition.
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Affiliation(s)
- Kevin A Murach
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA.,Molecular Muscle Mass Regulation Laboratory, Exercise Science Research Center, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, Arkansas, USA.,Cell and Molecular Biology Program, University of Arkansas, Fayetteville, Arkansas, USA
| | - Christopher S Fry
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA.,Department of Athletic Training and Clinical Nutrition, College of Health Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - Esther E Dupont-Versteegden
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA.,Department of Physical Therapy, College of Health Sciences, University of Kentucky, Lexington, Kentucky, USA
| | - John J McCarthy
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA.,Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Charlotte A Peterson
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA.,Department of Physical Therapy, College of Health Sciences, University of Kentucky, Lexington, Kentucky, USA.,Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
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42
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Eftestøl E, Franchi MV, Kasper S, Flück M. JNK activation in TA and EDL muscle is load-dependent in rats receiving identical excitation patterns. Sci Rep 2021; 11:16405. [PMID: 34385505 PMCID: PMC8361015 DOI: 10.1038/s41598-021-94930-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/12/2021] [Indexed: 11/09/2022] Open
Abstract
As the excitation-contraction coupling is inseparable during voluntary exercise, the relative contribution of the mechanical and neural input on hypertrophy-related molecular signalling is still poorly understood. Herein, we use a rat in-vivo strength exercise model with an electrically-induced standardized excitation pattern, previously shown to induce a load-dependent increase in myonuclear number and hypertrophy, to study acute effects of load on molecular signalling. We assessed protein abundance and specific phosphorylation of the four protein kinases FAK, mTOR, p70S6K and JNK after 2, 10 and 28 min of a low- or high-load contraction, in order to assess the effects of load, exercise duration and muscle-type on their response to exercise. Specific phosphorylation of mTOR, p70S6K and JNK was increased after 28 min of exercise under the low- and high-load protocol. Elevated phosphorylation of mTOR and JNK was detectable already after 2 and 10 min of exercise, respectively, but greatest after 28 min of exercise, and JNK phosphorylation was highly load-dependent. The abundance of all four kinases was higher in TA compared to EDL muscle, p70S6K abundance was increased after exercise in a load-independent manner, and FAK and JNK abundance was reduced after 28 min of exercise in both the exercised and control muscles. In conclusion, the current study shows that JNK activation after a single resistance exercise is load-specific, resembling the previously reported degree of myonuclear accrual and muscle hypertrophy with repetition of the exercise stimulus.
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Affiliation(s)
- Einar Eftestøl
- Department of Biosciences, University of Oslo, Kristine Bonnevies hus, Blindernveien 31, 0371, Oslo, Norway.
| | - Martino V Franchi
- Laboratory for Muscle Plasticity, Department of Orthopaedics, University of Zürich, Zurich, Switzerland.,Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Stephanie Kasper
- Laboratory for Muscle Plasticity, Department of Orthopaedics, University of Zürich, Zurich, Switzerland
| | - Martin Flück
- Laboratory for Muscle Plasticity, Department of Orthopaedics, University of Zürich, Zurich, Switzerland
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43
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Fukada SI, Nakamura A. Exercise/Resistance Training and Muscle Stem Cells. Endocrinol Metab (Seoul) 2021; 36:737-744. [PMID: 34372625 PMCID: PMC8419599 DOI: 10.3803/enm.2021.401] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 07/29/2021] [Indexed: 01/10/2023] Open
Abstract
Skeletal muscle has attracted attention as endocrine organ, because exercise-dependent cytokines called myokines/exerkines are released from skeletal muscle and are involved in systemic functions. While, local mechanical loading to skeletal muscle by exercise or resistance training alters myofiber type and size and myonuclear number. Skeletal muscle-resident stem cells, known as muscle satellite cells (MuSCs), are responsible for the increased number of myonuclei. Under steady conditions, MuSCs are maintained in a mitotically quiescent state but exit from that state and start to proliferate in response to high physical activity. Alterations in MuSC behavior occur when myofibers are damaged, but the lethal damage to myofibers does not seem to evoke mechanical loading-dependent MuSC activation and proliferation. Given that MuSCs proliferate without damage, it is unclear how the different behaviors of MuSCs are controlled by different physical activities. Recent studies demonstrated that myonuclear number reflects the size of myofibers; hence, it is crucial to know the properties of MuSCs and the mechanism of myonuclear accretion by MuSCs. In addition, the elucidation of mechanical load-dependent changes in muscle resident cells, including MuSCs, will be necessary for the discovery of new myokines/exerkines and understating skeletal muscle diseases.
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Affiliation(s)
- So-Ichiro Fukada
- Project for Muscle Stem Cell Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan
| | - Ayasa Nakamura
- Project for Muscle Stem Cell Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan
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44
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Battey E, Furrer R, Ross J, Handschin C, Ochala J, Stroud MJ. PGC-1α regulates myonuclear accretion after moderate endurance training. J Cell Physiol 2021; 237:696-705. [PMID: 34322871 DOI: 10.1002/jcp.30539] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 07/09/2021] [Accepted: 07/19/2021] [Indexed: 12/27/2022]
Abstract
The transcriptional demands of skeletal muscle fibres are high and require hundreds of nuclei (myonuclei) to produce specialised contractile machinery and multiple mitochondria along their length. Each myonucleus spatially regulates gene expression in a finite volume of cytoplasm, termed the myonuclear domain (MND), which positively correlates with fibre cross-sectional area (CSA). Endurance training triggers adaptive responses in skeletal muscle, including myonuclear accretion, decreased MND sizes and increased expression of the transcription co-activator peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α). Previous work has shown that overexpression of PGC-1α in skeletal muscle regulates mitochondrial biogenesis, myonuclear accretion and MND volume. However, whether PGC-1α is critical for these processes in adaptation to endurance training remained unclear. To test this, we evaluated myonuclear distribution and organisation in endurance-trained wild-type mice and mice lacking PGC-1α in skeletal muscle (PGC-1α mKO). Here, we show a differential myonuclear accretion response to endurance training that is governed by PGC-1α and is dependent on muscle fibre size. The positive relationship of MND size and muscle fibre CSA trended towards a stronger correlation in PGC-1a mKO versus control after endurance training, suggesting that myonuclear accretion was slightly affected with increasing fibre CSA in PGC-1α mKO. However, in larger fibres, the relationship between MND and CSA was significantly altered in trained versus sedentary PGC-1α mKO, suggesting that PGC-1α is critical for myonuclear accretion in these fibres. Accordingly, there was a negative correlation between the nuclear number and CSA, suggesting that in larger fibres myonuclear numbers fail to scale with CSA. Our findings suggest that PGC-1α is an important contributor to myonuclear accretion following moderate-intensity endurance training. This may contribute to the adaptive response to endurance training by enabling a sufficient rate of transcription of genes required for mitochondrial biogenesis.
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Affiliation(s)
- Edmund Battey
- Centre of Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, Faculty of Life Sciences & Medicine, King's College London, London, UK.,British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences & Medicine, King's College London, London, UK
| | | | - Jacob Ross
- British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences & Medicine, King's College London, London, UK
| | | | - Julien Ochala
- Centre of Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, Faculty of Life Sciences & Medicine, King's College London, London, UK.,Randall Centre for Cell and Molecular Biophysics, School of Basic & Medical Biosciences, Faculty of Life Sciences & Medicine, Guy's Campus, King's College London, London, UK.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Matthew J Stroud
- British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences & Medicine, King's College London, London, UK
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45
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Ohsawa I, Kawano F. Chronic exercise training activates histone turnover in mouse skeletal muscle fibers. FASEB J 2021; 35:e21453. [PMID: 33749947 DOI: 10.1096/fj.202002027rr] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 01/27/2021] [Accepted: 02/02/2021] [Indexed: 11/11/2022]
Abstract
Epigenetic regulation of skeletal muscle adaptation to exercise is a recent topic for which there is limited information. This study investigated whether exercise training activates histone turnover in the skeletal muscle fibers of mice. Experiments using a tetracycline-inducible H2B-GFP expression model demonstrated that 4 weeks of running training, but not 2 weeks of training, significantly promoted the incorporation of H2B-GFP into nucleosomes and the dissociation of histone H3.3 at both transcriptionally upregulated and nonresponsive loci. Muscle-specific PGC-1α-b-overexpressing mice crossed with H2B-GFP mice showed a slight increase in H2B-GFP incorporation at transcriptionally active loci, but not in the dissociation of H3.3 from nucleosomes. Gene expression responses to a single bout of running were significantly enhanced in 4-week trained mice when compared with those in 2-week trained mice. The most drastic increase in the gene response was found in the expression of Hspa1a and Hspa1b, in which the magnitude of upregulation in response to running was significantly enhanced from 8-fold in 2 week trained mice to 97- and 121-fold in 4 week trained mice, respectively. It was also found that the HSP70 level increased during the training period. In a myonuclear immunohistochemical analysis of chromatin remodelers, we further found that the level of SPT16, an H2A-H2B-specific chaperone, was upregulated after running training. These results revealed that 4 weeks of running training activated histone turnover in skeletal muscle fibers. They also suggested that histone turnover led to loosening of the nucleosomes and enhanced gene responses to exercise.
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Affiliation(s)
- Ikumi Ohsawa
- Graduate School of Health Sciences, Matsumoto University, Matsumoto City, Nagano, Japan
| | - Fuminori Kawano
- Graduate School of Health Sciences, Matsumoto University, Matsumoto City, Nagano, Japan
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46
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Kurosaka M, Ogura Y, Sato S, Kohda K, Funabashi T. Transcription factor signal transducer and activator of transcription 6 (STAT6) is an inhibitory factor for adult myogenesis. Skelet Muscle 2021; 11:14. [PMID: 34051858 PMCID: PMC8164270 DOI: 10.1186/s13395-021-00271-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 05/18/2021] [Indexed: 01/25/2023] Open
Abstract
Background The signal transducer and activator of transcription 6 (STAT6) transcription factor plays a vitally important role in immune cells, where it is activated mainly by interleukin-4 (IL-4). Because IL-4 is an essential cytokine for myotube formation, STAT6 might also be involved in myogenesis as part of IL-4 signaling. This study was conducted to elucidate the role of STAT6 in adult myogenesis in vitro and in vivo. Methods Myoblasts were isolated from male mice and were differentiated on a culture dish to evaluate the change in STAT6 during myotube formation. Then, the effects of STAT6 overexpression and inhibition on proliferation, differentiation, and fusion in those cells were studied. Additionally, to elucidate the myogenic role of STAT6 in vivo, muscle regeneration after injury was evaluated in STAT6 knockout mice. Results IL-4 can increase STAT6 phosphorylation, but STAT6 phosphorylation decreased during myotube formation in culture. STAT6 overexpression decreased, but STAT6 knockdown increased the differentiation index and the fusion index. Results indicate that STAT6 inhibited myogenin protein expression. Results of in vivo experiments show that STAT6 knockout mice exhibited better regeneration than wild-type mice 5 days after cardiotoxin-induced injury. It is particularly interesting that results obtained using cells from STAT6 knockout mice suggest that this STAT6 inhibitory action for myogenesis was not mediated by IL-4 but might instead be associated with p38 mitogen-activated protein kinase phosphorylation. However, STAT6 was not involved in the proliferation of myogenic cells in vitro and in vivo. Conclusion Results suggest that STAT6 functions as an inhibitor of adult myogenesis. Moreover, results suggest that the IL-4-STAT6 signaling axis is unlikely to be responsible for myotube formation. Supplementary Information The online version contains supplementary material available at 10.1186/s13395-021-00271-8.
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Affiliation(s)
- Mitsutoshi Kurosaka
- Department of Physiology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, 216-8511, Japan
| | - Yuji Ogura
- Department of Physiology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, 216-8511, Japan.
| | - Shuichi Sato
- School of Kinesiology, The University of Louisiana at Lafayette, Lafayette, LA, USA.,New Iberia Research Center, The University of Louisiana at Lafayette, New Iberia, LA, USA
| | - Kazuhisa Kohda
- Department of Physiology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, 216-8511, Japan
| | - Toshiya Funabashi
- Department of Physiology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, 216-8511, Japan
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47
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Prasad V, Millay DP. Skeletal muscle fibers count on nuclear numbers for growth. Semin Cell Dev Biol 2021; 119:3-10. [PMID: 33972174 DOI: 10.1016/j.semcdb.2021.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/30/2021] [Accepted: 04/19/2021] [Indexed: 02/06/2023]
Abstract
Skeletal muscle cells are noteworthy for their syncytial nature, with each myofiber accumulating hundreds or thousands of nuclei derived from resident muscle stem cells (MuSCs). These nuclei are accrued through cell fusion, which is controlled by the two essential fusogens Myomaker and Myomerger that are transiently expressed within the myogenic lineage. While the absolute requirement of fusion for muscle development has been known for decades, the underlying need for the magnitude of multinucleation in muscle remains mysterious. Possible advantages of multinucleation include the potential it affords for transcriptional diversity within these massive cells, and as a means of increasing DNA content to support optimal cell size and function. In this article, we review recent advances that elucidate the relationship between myonuclear numbers and establishment of myofiber size, and discuss how this new information refines our understanding of the concept of myonuclear domains (MND), the cytoplasmic volumes that each resident myonucleus can support. Finally, we explore the potential consequences and costs of multinucleation and its impacts on myonuclear transcriptional reserve capacity, growth potential, myofiber size regulation, and muscle adaptability. We anticipate this report will not only serve to highlight the latest advances in the basic biology of syncytial muscle cells but also provide information to help design the next generation of therapeutic strategies to maintain muscle mass and function.
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Affiliation(s)
- Vikram Prasad
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Douglas P Millay
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.
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48
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Rahmati M, Taherabadi SJ. The effects of exercise training on Kinesin and GAP-43 expression in skeletal muscle fibers of STZ-induced diabetic rats. Sci Rep 2021; 11:9535. [PMID: 33953268 PMCID: PMC8099856 DOI: 10.1038/s41598-021-89106-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 04/21/2021] [Indexed: 02/07/2023] Open
Abstract
Kinesin-1 and Growth Associated Protein 43 (GAP-43) localization in muscle fiber are crucial for proper skeletal muscle hypertrophy. To evaluate this assumption, we investigated the beneficial effects of endurance training on GAP-43 and Kinesin Family Member 5B (KIF5B) expression in gastrocnemius muscle of streptozotocin (STZ)-induced diabetic rats. Fifty-two male rats were randomly divided into four groups: healthy control (C), healthy trained (T), diabetic control (DC) and diabetic trained (DT). Diabetes was induced by a single intraperitoneal injection of STZ (45 mg/kg). The rats in DT and T groups were subjected to treadmill running for 5 days a week over 6 weeks. The results indicated that the GAP-43 and KIF5B protein levels in the DC group were significantly lower than those in the C group. Additionally, chronic treadmill running in diabetic rats was accompanied by significant increase of GAP-43 and KIF5B protein expression, compared to DC group. Furthermore, the endurance training in healthy rats was associated with a significant increase of GAP-43 and KIF5B protein levels. In addition, we found positive correlation between GAP-43 and KIF5B protein levels and myonuclear number per fiber and average gastrocnemius cross-sectional area (CSA). GAP43 and KIF5B protein levels were decreased in skeletal muscles of diabetic rats, and exercise training had beneficial effects and could restore their abnormal expression. Moreover, there is a strong relationship between muscle hypertrophy and GAP-43 and KIF5B protein levels.
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Affiliation(s)
- Masoud Rahmati
- Department of Physical Education and Sport Sciences, Faculty of Literature and Human Sciences, Lorestan University, Khoramabad, Iran.
| | - Seyed Jalal Taherabadi
- Department of Physical Education and Sport Sciences, Faculty of Literature and Human Sciences, Lorestan University, Khoramabad, Iran
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49
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Solsona R, Pavlin L, Bernardi H, Sanchez AMJ. Molecular Regulation of Skeletal Muscle Growth and Organelle Biosynthesis: Practical Recommendations for Exercise Training. Int J Mol Sci 2021; 22:2741. [PMID: 33800501 PMCID: PMC7962973 DOI: 10.3390/ijms22052741] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 12/18/2022] Open
Abstract
The regulation of skeletal muscle mass and organelle homeostasis is dependent on the capacity of cells to produce proteins and to recycle cytosolic portions. In this investigation, the mechanisms involved in skeletal muscle mass regulation-especially those associated with proteosynthesis and with the production of new organelles-are presented. Thus, the critical roles of mammalian/mechanistic target of rapamycin complex 1 (mTORC1) pathway and its regulators are reviewed. In addition, the importance of ribosome biogenesis, satellite cells involvement, myonuclear accretion, and some major epigenetic modifications related to protein synthesis are discussed. Furthermore, several studies conducted on the topic of exercise training have recognized the central role of both endurance and resistance exercise to reorganize sarcomeric proteins and to improve the capacity of cells to build efficient organelles. The molecular mechanisms underlying these adaptations to exercise training are presented throughout this review and practical recommendations for exercise prescription are provided. A better understanding of the aforementioned cellular pathways is essential for both healthy and sick people to avoid inefficient prescriptions and to improve muscle function with emergent strategies (e.g., hypoxic training). Finally, current limitations in the literature and further perspectives, notably on epigenetic mechanisms, are provided to encourage additional investigations on this topic.
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Affiliation(s)
- Robert Solsona
- Laboratoire Interdisciplinaire Performance Santé Environnement de Montagne (LIPSEM), Faculty of Sports Sciences, University of Perpignan Via Domitia, UR 4640, 7 Avenue Pierre de Coubertin, 66120 Font-Romeu, France;
| | - Laura Pavlin
- DMEM, University of Montpellier, INRAE UMR866, 2 Place Pierre Viala, 34060 Montpellier, France; (L.P.); (H.B.)
| | - Henri Bernardi
- DMEM, University of Montpellier, INRAE UMR866, 2 Place Pierre Viala, 34060 Montpellier, France; (L.P.); (H.B.)
| | - Anthony MJ Sanchez
- Laboratoire Interdisciplinaire Performance Santé Environnement de Montagne (LIPSEM), Faculty of Sports Sciences, University of Perpignan Via Domitia, UR 4640, 7 Avenue Pierre de Coubertin, 66120 Font-Romeu, France;
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50
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Shirai T, Hanakita H, Uemichi K, Takemasa T. Effect of the order of concurrent training combined with resistance and high-intensity interval exercise on mTOR signaling and glycolytic metabolism in mouse skeletal muscle. Physiol Rep 2021; 9:e14770. [PMID: 33650809 PMCID: PMC7923557 DOI: 10.14814/phy2.14770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 01/28/2021] [Accepted: 02/01/2021] [Indexed: 02/07/2023] Open
Abstract
Athletes train to improve strength and endurance to demonstrate maximum performance during competitions. Training methods vary but most focus on strength, endurance, or both. Concurrent training is a combination of two different modes of training. In this study, we combined resistance exercise (RE) and high-intensity interval exercise (HIIE) to investigate the influence of the order of the concurrent training on signal molecules on hypertrophy and glycolysis in the skeletal muscle. The phosphorylation levels of mechanistic target of rapamycin (mTOR) signals, p70 S6 kinase (p70S6 K), ribosomal protein S6 (S6), and glycogen synthase kinase beta (GSK-3β) were significantly increased in the HIIE first group compared with the control group. The combined training course did not affect the glycogen content and expression levels of proteins concerning glycolytic and metabolic capacity, suggesting that a combination of HIIE and RE on the same day, with HIIE prior to RE, improves hypertrophy response and glycolysis enhancement.
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Affiliation(s)
- Takanaga Shirai
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.,Research Fellow of Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo, Japan
| | - Hideto Hanakita
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Kazuki Uemichi
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Tohru Takemasa
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
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