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Iwamori K, Kubota M, Zhang L, Kodama K, Kubo A, Kokubo H, Akimoto T, Fukada SI. Decreased number of satellite cells-derived myonuclei in both fast- and slow-twitch muscles in HeyL-KO mice during voluntary running exercise. Skelet Muscle 2024; 14:25. [PMID: 39449015 DOI: 10.1186/s13395-024-00357-z] [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: 06/05/2024] [Accepted: 10/09/2024] [Indexed: 10/26/2024] Open
Abstract
BACKGROUND Skeletal muscles possess unique abilities known as adaptation or plasticity. When exposed to external stimuli, such as mechanical loading, both myofiber size and myonuclear number increase. Muscle stem cells, also known as muscle satellite cells (MuSCs), play vital roles in these changes. HeyL, a direct target of Notch signaling, is crucial for efficient muscle hypertrophy because it ensures MuSC proliferation in surgically overloaded muscles by inhibiting the premature differentiation. However, it remains unclear whether HeyL is essential for MuSC expansion in physiologically exercised muscles. Additionally, the influence of myofiber type on the requirement for HeyL in MuSCs within exercised muscles remains unclear. METHODS We used a voluntary wheel running model and HeyL-knockout mice to investigate the impact of HeyL deficiency on MuSC-derived myonuclei, MuSC behavior, muscle weight, myofiber size, and myofiber type in the running mice. RESULTS The number of new MuSC-derived myonuclei was significantly lower in both slow-twitch soleus and fast-twitch plantaris muscles from exercised HeyL-knockout mice than in control mice. However, expect for the frequency of Type IIb myofiber in plantaris muscle, exercised HeyL-knockout mice exhibited similar responses to control mice regarding myofiber size and type. CONCLUSIONS HeyL expression is crucial for MuSC expansion during physiological exercise in both slow and fast muscles. The frequency of Type IIb myofiber in plantaris muscle of HeyL-knockout mice was not significantly reduced compared to that of control mice. However, the absence of HeyL did not affect the increased size and frequency of Type IIa myofiber in plantaris muscles. In this model, no detectable changes in myofiber size or type were observed in the soleus muscles of either control or HeyL-knockout mice. These findings imply that the requirement for MuSCs in the wheel-running model is difficult to observe due to the relatively low degree of hypertrophy compared to surgically overloaded models.
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Affiliation(s)
- Kanako Iwamori
- Laboratory of Stem Cell Regeneration and Adaptation, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, 565-0871, Osaka, Japan
| | - Manami Kubota
- Laboratory of Stem Cell Regeneration and Adaptation, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, 565-0871, Osaka, Japan
| | - Lidan Zhang
- Laboratory of Stem Cell Regeneration and Adaptation, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, 565-0871, Osaka, Japan
- Center for Medical Epigenetics, School of Basic Medical Sciences, Chongqing Medical University, Chongqing, 40016, China
| | - Kazuki Kodama
- Laboratory of Stem Cell Regeneration and Adaptation, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, 565-0871, Osaka, Japan
| | - Atsushi Kubo
- Laboratory of Stem Cell Regeneration and Adaptation, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, 565-0871, Osaka, Japan
| | - Hiroki Kokubo
- Department of Cardiovascular Physiology and Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan
| | - Takayuki Akimoto
- Faculty of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, 359-1192, Saitama, Japan
| | - So-Ichiro Fukada
- Laboratory of Stem Cell Regeneration and Adaptation, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, 565-0871, Osaka, Japan.
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Lee SB, Woo TW, Baek DC, Son CG. A standardized herbal combination of Astragalus membranaceus and Paeonia japonica promotes skeletal muscle hypertrophy in a treadmill exercise mouse model. Front Nutr 2024; 11:1362550. [PMID: 38966418 PMCID: PMC11223055 DOI: 10.3389/fnut.2024.1362550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 05/29/2024] [Indexed: 07/06/2024] Open
Abstract
Background Maintaining a normal range of muscle mass and function is crucial not only for sustaining a healthy life but also for preventing various disorders. Numerous nutritional or natural resources are being explored for their potential muscle hypertrophic properties. Aim We aimed to evaluate the muscle hypertrophic effects of APX, a 1:1 mixture of Astragalus membranaceus and Paeonia japonica. In addition to the myotube differentiation cell assay, we utilized a weighted exercise-based animal model and evaluated changes in muscle hypertrophy using dual-energy X-ray absorptiometry (DXA) and histological analysis. Results The 8-week treadmill exercise led to notable decreases in body weight and fat mass but an increase in muscle mass compared to the control group. Administration of APX significantly accelerated muscle mass gain (p < 0.05) without altering body weight or fat mass compared to the exercise-only group. This muscle hypertrophic effect of APX was consistent with the histologic size of muscle fibers in the gastrocnemius (p > 0.05) and rectus femoris (p < 0.05), as well as the regulation of myogenic transcription factors (MyoD and myogenin), respectively. Furthermore, APX demonstrated a similar action to insulin-like growth factor 1, influencing the proliferation of C2C12 myoblast cells (p < 0.01) and their differentiation into myotubes (p < 0.05) compared to the control group. Conclusion The present study provides experimental evidence that APX has muscle hypertrophic effects, and its underlying mechanisms would involve the modulation of MyoD and myogenin.
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Affiliation(s)
| | | | | | - Chang-Gue Son
- Institute of Traditional Medicine and Bioscience, Daejeon University, Daejeon, Republic of Korea
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Dzirkale Z, Pilipenko V, Pijet B, Klimaviciusa L, Upite J, Protokowicz K, Kaczmarek L, Jansone B. Long-term behavioural alterations in mice following transient cerebral ischemia. Behav Brain Res 2023; 452:114589. [PMID: 37481076 DOI: 10.1016/j.bbr.2023.114589] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/05/2023] [Accepted: 07/17/2023] [Indexed: 07/24/2023]
Abstract
Ischemic stroke is one of the leading causes of disability and mortality worldwide. Acute and chronic post-stroke changes have variable effects on the functional outcomes of the disease. Therefore, it is imperative to identify what daily activities are altered after stroke and to what extent, keeping in mind that ischemic stroke patients often have long-term post-stroke complications. Translational studies in stroke have also been challenging due to inconsistent study design of animal experiments. The objective of this study was to clarify whether and to what extent mouse behaviour was altered during a 6 months period after cerebral stroke. Experimental stroke was induced in mice by intraluminal filament insertion into the middle cerebral artery (fMCAo). Neurological deficits, recovery rate, motor performance, and circadian activity were evaluated following ischemia. We observed severe neurological deficits, motor impairments, and delay in the recovery rate of mice during the first 14 days after fMCAo. Aberrant circadian activity and distorted space map were seen in fMCAo mice starting one month after ischemia, similarly to altered new and familiar cage activity and sucrose preference using the IntelliCage, and was still evident 60- and 180- days following stroke in the voluntary running wheel using the PhenoMaster system. A preference towards ipsilateral side turns was observed in fMCAo mice both acutely and chronically after the stroke induction. Overall, our study shows the importance of determining time-dependent differences in the long-term post-stroke recovery (over 180 days after fMCAo) using multiple behavioural assessments.
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Affiliation(s)
- Zane Dzirkale
- Department of Pharmacology, Faculty of Medicine, University of Latvia, 3 Jelgavas Street, LV-1004 Riga, Latvia.
| | - Vladimirs Pilipenko
- Department of Pharmacology, Faculty of Medicine, University of Latvia, 3 Jelgavas Street, LV-1004 Riga, Latvia
| | - Barbara Pijet
- Laboratory of Neurobiology, BRAINCITY - Centre of Excellence for Neural Plasticity and Brain Disorders, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Linda Klimaviciusa
- Department of Pharmacology, Faculty of Medicine, University of Latvia, 3 Jelgavas Street, LV-1004 Riga, Latvia
| | - Jolanta Upite
- Department of Pharmacology, Faculty of Medicine, University of Latvia, 3 Jelgavas Street, LV-1004 Riga, Latvia
| | - Karolina Protokowicz
- Laboratory of Neurobiology, BRAINCITY - Centre of Excellence for Neural Plasticity and Brain Disorders, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Leszek Kaczmarek
- Laboratory of Neurobiology, BRAINCITY - Centre of Excellence for Neural Plasticity and Brain Disorders, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Baiba Jansone
- Department of Pharmacology, Faculty of Medicine, University of Latvia, 3 Jelgavas Street, LV-1004 Riga, Latvia.
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D'Hulst G, Masschelein E, De Bock K. Resistance exercise enhances long-term mTORC1 sensitivity to leucine. Mol Metab 2022; 66:101615. [PMID: 36252815 PMCID: PMC9626937 DOI: 10.1016/j.molmet.2022.101615] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 10/07/2022] [Accepted: 10/12/2022] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE Exercise enhances the sensitivity of mammalian target of rapamycin complex 1 (mTORC1) to amino acids, in particular leucine. How long this enhanced sensitivity lasts, and which mechanisms control enhanced leucine-mediated mTORC1 activation following exercise is currently unknown. METHODS C57BL/6J mice were exercised for one night in a resistance-braked running wheel after a 12-day acclimatization period. Mice were gavaged with a submaximal dose of l-leucine or saline acutely or 48 h after exercise cessation, following 3 h food withdrawal. Muscles were excised 30 min after leucine administration. To study the contribution of mTORC1, we repeated those experiments but blocked mTORC1 activation using rapamycin immediately before the overnight running bout and one hour before the first dose of leucine. mTORC1 signaling, muscle protein synthesis and amino acid sensing machinery were assessed using immunoblot and qPCR. Leucine uptake was measured using L-[14C(U)]-leucine tracer labeling. RESULTS When compared to sedentary conditions, leucine supplementation more potently activated mTORC1 and protein synthesis in acutely exercised muscle. This effect was observed in m. soleus but not in m. tibialis anterior nor m. plantaris. The synergistic effect in m. soleus was long-lasting as key downstream markers of mTORC1 as well as protein synthesis remained higher when leucine was administered 48 h after exercise. We found that exercise enhanced the expression of amino acid transporters and promoted uptake of leucine into the muscle, leading to higher free intramuscular leucine levels. This coincided with increased expression of activating transcription factor 4 (ATF4), a main transcriptional regulator of amino acid uptake and metabolism, and downstream activation of amino acid genes as well as leucyl-tRNA synthetase (LARS), a putative leucine sensor. Finally, blocking mTORC1 using rapamycin did not reduce expression and activation of ATF4, suggesting that the latter does not act downstream of mTORC1. Rather, we found a robust increase in eukaryotic initiation factor 2α (eIF2α) phosphorylation, suggesting that the integrated stress response pathway, rather than exercise-induced mTORC1 activation, drives long-term ATF4 expression in skeletal muscle after exercise. CONCLUSIONS The enhanced sensitivity of mTORC1 to leucine is maintained at least 48 h after exercise. This shows that the anabolic window of opportunity for protein ingestion is not restricted to the first hours immediately following exercise. Increased mTORC1 sensitivity to leucine coincided with enhanced leucine influx into muscle and higher expression of genes involved in leucine sensing and amino acid metabolism. Also, exercise induced an increase in ATF4 protein expression. Altogether, these data suggest that muscular contractions switch on a coordinated program to enhance amino acid uptake as well as intramuscular sensing of key amino acids involved in mTORC1 activation and the stimulation of muscle protein synthesis.
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Affiliation(s)
- Gommaar D'Hulst
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zürich, Switzerland
| | - Evi Masschelein
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zürich, Switzerland
| | - Katrien De Bock
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zürich, Switzerland.
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Reed CH, Buhr TJ, Tystahl AC, Bauer EE, Clark PJ, Valentine RJ. The effects of voluntary binge-patterned ethanol ingestion and daily wheel running on signaling of muscle protein synthesis and degradation in female mice. Alcohol 2022; 104:45-52. [PMID: 35926812 DOI: 10.1016/j.alcohol.2022.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/17/2022] [Accepted: 06/22/2022] [Indexed: 01/26/2023]
Abstract
Excessive ethanol ingestion can reduce skeletal muscle protein synthesis (MPS) through the disruption of signaling along the Akt-mTOR pathway and increase muscle protein degradation (MPD) through the Ubiquitin Proteasome Pathway (UPP) and autophagy. Identification of interventions that curb the disrupting effects of alcohol misuse on MPS and MPD are of central importance for the prevention of chronic health complications that arise from muscle loss. Physical activity is one potential strategy to combat the deleterious effects of alcohol on skeletal muscle. Therefore, the purpose of this study was to investigate the interaction between daily wheel running and binge-patterned ethanol consumption, through episodes of voluntary binge-patterned ethanol drinking, on signaling factors along the Akt-mTOR, Ubiquitin-Proteasome, and autophagy pathways. Adult female C57BL/6J mice received daily access to cages with or without running wheels for 2.5 h/day for five weeks. During the final five days of the study, mice received 2-4 h of daily access to sipper tubes containing water (n = 14 sedentary; n = 15 running) or 20% ethanol (n = 14 sedentary; n = 16 running) 30 min after running wheel access, using the "Drinking in the Dark" (DID) model of binge-patterned ethanol consumption. Immediately after the final episode of DID, gastrocnemius muscle was extracted. Western blotting was performed to measure proteins along Akt-mTOR, Ubiquitin-Proteasome, and autophagy pathways, and PCR was used to assess mRNA expression of atrogenes. Ethanol access increased expression of MAFbx by 82% (p = 0.048), but did not robustly influence Akt-mTOR or UPP signaling. Daily wheel access did not prevent alcohol-induced MAFbx expression; however, ethanol access decreased the phosphorylation of p70S6K by 45% in running mice (p = 0.020). These results suggest that physical activity may be insufficient to prevent alcohol-induced changes to signaling factors along pathways involved in muscle loss. Instead, binge-patterned ethanol ingestion may impair the benefits of physical activity on factors involved in MPS.
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Affiliation(s)
- Carter H Reed
- Department of Kinesiology, Forker Building, 534 Wallace Road, Iowa State University, Ames, IA, 50011, United States; Interdepartmental Graduate Program of Nutritional Sciences, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States
| | - Trevor J Buhr
- Neuroscience Program, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States; Department of Food Science and Human Nutrition, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States
| | - Anna C Tystahl
- Department of Kinesiology, Forker Building, 534 Wallace Road, Iowa State University, Ames, IA, 50011, United States
| | - Ella E Bauer
- Interdepartmental Graduate Program of Nutritional Sciences, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States; Neuroscience Program, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States; Department of Food Science and Human Nutrition, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States
| | - Peter J Clark
- Interdepartmental Graduate Program of Nutritional Sciences, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States; Neuroscience Program, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States; Department of Food Science and Human Nutrition, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States.
| | - Rudy J Valentine
- Department of Kinesiology, Forker Building, 534 Wallace Road, Iowa State University, Ames, IA, 50011, United States; Interdepartmental Graduate Program of Nutritional Sciences, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States; Neuroscience Program, MacKay Hall, 2302 Osborn Drive, Iowa State University, Ames, IA, 50011, United States.
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Hodson N, Mazzulla M, Holowaty MNH, Kumbhare D, Moore DR. RPS6 phosphorylation occurs to a greater extent in the periphery of human skeletal muscle fibers, near focal adhesions, after anabolic stimuli. Am J Physiol Cell Physiol 2021; 322:C94-C110. [PMID: 34852208 DOI: 10.1152/ajpcell.00357.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Following anabolic stimuli (mechanical loading and/or amino acid provision) the mechanistic target of rapamycin complex 1 (mTORC1), a master regulator of protein synthesis, translocates toward the cell periphery. However, it is unknown if mTORC1-mediated phosphorylation events occur in these peripheral regions or prior to translocation (i.e. in central regions). We therefore aimed to determine the cellular location of a mTORC1-mediated phosphorylation event, RPS6Ser240/244, in human skeletal muscle following anabolic stimuli. Fourteen young, healthy males either ingested a protein-carbohydrate beverage (0.25g/kg protein, 0.75g/kg carbohydrate) alone (n=7;23±5yrs;76.8±3.6kg;13.6±3.8%BF, FED) or following a whole-body resistance exercise bout (n=7;22±2yrs;78.1±3.6kg;12.2±4.9%BF, EXFED). Vastus lateralis muscle biopsies were obtained at rest (PRE) and 120 and 300min following anabolic stimuli. RPS6Ser240/244 phosphorylation measured by immunofluorescent staining or immunoblot was positively correlated (r=0.76, p<0.001). Peripheral staining intensity of p-RPS6Ser240/244 increased above PRE in both FED and EXFED at 120min (~54% and ~138% respectively, p<0.05) but was greater in EXFED at both post-stimuli time points (p<0.05). The peripheral-central ratio of p-RPS6240/244 staining displayed a similar pattern, even when corrected for total RPS6 distribution, suggesting RPS6 phosphorylation occurs to a greater extent in the periphery of fibers. Moreover, p-RPS6Ser240/244 intensity within paxillin-positive regions, a marker of focal adhesion complexes, was elevated at 120min irrespective of stimulus (p=0.006) before returning to PRE at 300min. These data confirm that RPS6Ser240/244 phosphorylation occurs in the region of human muscle fibers to which mTOR translocates following anabolic stimuli and identifies focal adhesion complexes as a potential site of mTORC1 regulation in vivo.
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Affiliation(s)
- Nathan Hodson
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
| | - Michael Mazzulla
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
| | - Maksym N H Holowaty
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
| | | | - Daniel R Moore
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
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Scheuren AC, D'Hulst G, Kuhn GA, Masschelein E, Wehrle E, De Bock K, Müller R. Hallmarks of frailty and osteosarcopenia in prematurely aged PolgA (D257A/D257A) mice. J Cachexia Sarcopenia Muscle 2020; 11:1121-1140. [PMID: 32596975 PMCID: PMC7432580 DOI: 10.1002/jcsm.12588] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/14/2020] [Accepted: 02/24/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Frailty is a geriatric syndrome characterized by increased susceptibility to adverse health outcomes. One major determinant thereof is the gradual weakening of the musculoskeletal system and the associated osteosarcopenia. To improve our understanding of the underlying pathophysiology and, more importantly, to test potential interventions aimed at counteracting frailty, suitable animal models are needed. METHODS To evaluate the relevance of prematurely aged PolgA(D257A/D257A) mice as a model for frailty and osteosarcopenia, we quantified the clinical mouse frailty index in PolgA(D257A/D257A) and wild-type littermates (PolgA(+/+) , WT) with age and concertedly assessed the quantity and quality of bone and muscle tissue. Lastly, the anabolic responsiveness of skeletal muscle, muscle progenitors, and bone was assessed. RESULTS PolgA(D257A/D257A) accumulated health deficits at a higher rate compared with WT, resulting in a higher frailty index at 40 and 46 weeks of age (+166%, +278%, P < 0.0001), respectively, with no differences between genotypes at 34 weeks. Concomitantly, PolgA(D257A/D257A) displayed progressive musculoskeletal deterioration such as reduced bone and muscle mass as well as impaired functionality thereof. In addition to lower muscle weights (-14%, P < 0.05, -23%, P < 0.0001) and fibre area (-20%, P < 0.05, -22%, P < 0.0001) at 40 and 46 weeks, respectively, PolgA(D257A/D257A) showed impairments in grip strength and concentric muscle forces (P < 0.05). PolgA(D257A/D257A) mutation altered the acute response to various anabolic stimuli in skeletal muscle and muscle progenitors. While PolgA(D257A/D257A) muscles were hypersensitive to eccentric contractions as well as leucine administration, shown by larger downstream signalling response of the mechanistic target of rapamycin complex 1, myogenic progenitors cultured in vitro showed severe anabolic resistance to leucine and robust impairments in cell proliferation. Longitudinal micro-computed tomography analysis of the sixth caudal vertebrae showed that PolgA(D257A/D257A) had lower bone morphometric parameters (e.g. bone volume fraction, trabecular, and cortical thickness, P < 0.05) as well as reduced remodelling activities (e.g. bone formation and resorption rate, P < 0.05) compared with WT. When subjected to 4 weeks of cyclic loading, young but not aged PolgA(D257A/D257A) caudal vertebrae showed load-induced bone adaptation, suggesting reduced mechanosensitivity with age. CONCLUSIONS PolgA(D257A/D257A) mutation leads to hallmarks of age-related frailty and osteosarcopenia and provides a powerful model to better understand the relationship between frailty and the aging musculoskeletal system.
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Affiliation(s)
| | - Gommaar D'Hulst
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | | | - Evi Masschelein
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | - Esther Wehrle
- Institute for BiomechanicsETH ZurichZurichSwitzerland
| | - Katrien De Bock
- Laboratory of Exercise and HealthETH ZurichZurichSwitzerland
| | - Ralph Müller
- Institute for BiomechanicsETH ZurichZurichSwitzerland
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Murach KA, McCarthy JJ, Peterson CA, Dungan CM. Making Mice Mighty: recent advances in translational models of load-induced muscle hypertrophy. J Appl Physiol (1985) 2020; 129:516-521. [PMID: 32673155 DOI: 10.1152/japplphysiol.00319.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The ability to genetically manipulate mice allows for gain- and loss-of-function in vivo, making them an ideal model for elucidating mechanisms of skeletal muscle mass regulation. Combining genetic models with mechanical muscle loading enables identification of specific factors involved in the hypertrophic response as well as the ability to test the requirement of those factors for adaptation, thereby informing performance and therapeutic interventions. Until recently, approaches for inducing mechanically mediated muscle hypertrophy (i.e., resistance-training analogs) have been limited and considered "nontranslatable" to humans. This mini-review outlines recent translational advances in loading-mediated strategies for inducing muscle hypertrophy in mice, and highlights the advantages and disadvantages of each method. The skeletal muscle field is poised for new breakthroughs in understanding mechanisms regulating load-induced muscle growth given the numerous murine tools that have very recently been described.
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Affiliation(s)
- Kevin A Murach
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky.,Department of Physical Therapy, College of Health Sciences, University of Kentucky, Lexington, Kentucky
| | - John J McCarthy
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky.,Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Charlotte A Peterson
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky.,Department of Physical Therapy, College of Health Sciences, University of Kentucky, Lexington, Kentucky.,Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Cory M Dungan
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky.,Department of Physical Therapy, College of Health Sciences, University of Kentucky, Lexington, Kentucky
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Masschelein E, D'Hulst G, Zvick J, Hinte L, Soro-Arnaiz I, Gorski T, von Meyenn F, Bar-Nur O, De Bock K. Exercise promotes satellite cell contribution to myofibers in a load-dependent manner. Skelet Muscle 2020; 10:21. [PMID: 32646489 PMCID: PMC7346400 DOI: 10.1186/s13395-020-00237-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/15/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Satellite cells (SCs) are required for muscle repair following injury and are involved in muscle remodeling upon muscular contractions. Exercise stimulates SC accumulation and myonuclear accretion. To what extent exercise training at different mechanical loads drive SC contribution to myonuclei however is unknown. RESULTS By performing SC fate tracing experiments, we show that 8 weeks of voluntary wheel running increased SC contribution to myofibers in mouse plantar flexor muscles in a load-dependent, but fiber type-independent manner. Increased SC fusion however was not exclusively linked to muscle hypertrophy as wheel running without external load substantially increased SC fusion in the absence of fiber hypertrophy. Due to nuclear propagation, nuclear fluorescent fate tracing mouse models were inadequate to quantify SC contribution to myonuclei. Ultimately, by performing fate tracing at the DNA level, we show that SC contribution mirrors myonuclear accretion during exercise. CONCLUSIONS Collectively, mechanical load during exercise independently promotes SC contribution to existing myofibers. Also, due to propagation of nuclear fluorescent reporter proteins, our data warrant caution for the use of existing reporter mouse models for the quantitative evaluation of satellite cell contribution to myonuclei.
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Affiliation(s)
- Evi Masschelein
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Gommaar D'Hulst
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Joel Zvick
- Department Health Sciences and Technology, Laboratory of Regenerative and Movement Biology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Laura Hinte
- Department Health Sciences and Technology, Laboratory of Nutrition and Metabolic Epigenetics, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Inés Soro-Arnaiz
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Tatiane Gorski
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Ferdinand von Meyenn
- Department Health Sciences and Technology, Laboratory of Nutrition and Metabolic Epigenetics, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Ori Bar-Nur
- Department Health Sciences and Technology, Laboratory of Regenerative and Movement Biology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Katrien De Bock
- Department Health Sciences and Technology, Laboratory of Exercise and Health, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland.
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