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Salimi K, Alvandi M, Saberi Pirouz M, Rakhshan K, Howatson G. Regulating eEF2 and eEF2K in skeletal muscle by exercise. Arch Physiol Biochem 2023:1-12. [PMID: 36633938 DOI: 10.1080/13813455.2023.2164898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/15/2022] [Accepted: 12/29/2022] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is a flexible and adaptable tissue that strongly responds to exercise training. The skeletal muscle responds to exercise by increasing muscle protein synthesis (MPS) when energy is available. One of protein synthesis's major rate-limiting and critical regulatory steps is the translation elongation pathway. The process of translation elongation in skeletal muscle is highly regulated. It requires elongation factors that are intensely affected by various physiological stimuli such as exercise and the total available energy of cells. Studies have shown that exercise involves the elongation pathway by numerous signalling pathways. Since the elongation pathway, has been far less studied than the other translation steps, its comprehensive prospect and quantitative understanding remain in the dark. This study highlights the current understanding of the effect of exercise training on the translation elongation pathway focussing on the molecular factors affecting the pathway, including Ca2+, AMPK, PKA, mTORC1/P70S6K, MAPKs, and myostatin. We further discussed the mode and volume of exercise training intervention on the translation elongation pathway.What is the topic of this review? This review summarises the impacts of exercise training on the translation elongation pathway in skeletal muscle focussing on eEF2 and eEF2K.What advances does it highlight? This review highlights mechanisms and factors that profoundly influence the translation elongation pathway and argues that exercise might modulate the response. This review also combines the experimental observations focussing on the regulation of translation elongation during and after exercise. The findings widen our horizon to the notion of mechanisms involved in muscle protein synthesis (MPS) through translation elongation response to exercise training.
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Affiliation(s)
- Kia Salimi
- Department of Exercise Physiology, Faculty of Sport and Exercise Sciences, University of Tehran, Tehran, Iran
| | - Masoomeh Alvandi
- Department of Biological Science in Sport and Health, University of Shahid Beheshti, Tehran, Iran
| | - Mahdi Saberi Pirouz
- Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - Kamran Rakhshan
- Department of Medical Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Electrophysiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Water Research Group, North West University, Potchefstroom, South Africa
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2
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Divvela SSK, Offei EB, Suerland F, Revuelta García D, Kwiatkowski J, Balakrishnan-Renuka A, Bohne P, Böing M, Morosan-Puopolo G, Mark MD, Brand-Saberi B. Atonal homolog 8/Math6 regulates differentiation and maintenance of skeletal muscle. Front Cell Dev Biol 2022; 10:950414. [PMID: 36060799 PMCID: PMC9438786 DOI: 10.3389/fcell.2022.950414] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 07/06/2022] [Indexed: 12/16/2022] Open
Abstract
Atonal Homolog 8 (Atoh8) belongs to a large superfamily of transcriptional regulators called basic helix-loop-helix (bHLH) transcription factors. Atoh8 (murine homolog “Math6”) has been shown to be involved in organogenesis during murine embryonic development. We have previously identified the expression of Atoh8 during skeletal myogenesis in chicken where we described its involvement in hypaxial myotome formation suggesting a regulatory role of Atoh8 in skeletal muscle development. Within the current study, we analyzed the effect of the loss of function of Atoh8 in murine primary myoblasts and during differentiation of pluripotent stem cells into myotubes, and the effect of its gain of function in C2C12 cells. Based on the observed results, we conclude that Atoh8 regulates myoblast proliferation via modulating myostatin signaling. Further, our data revealed a reduced muscle mass, strength and fiber size with significant changes to the muscle fiber type suggesting atrophy in skeletal muscle of Atoh8 mutants. We further report that Atoh8 knockout mice suffer from a condition similar to ambient hypoxia which may be the primary cause of the phenotype. Altogether, this study shows the significance of Atoh8 not only in myogenesis but also in the maintenance of skeletal muscle.
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Affiliation(s)
| | - Eric Bekoe Offei
- Department of Anatomy and Molecular Embryology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
- University of Ghana, School of Veterinary Medicine, Legon, Ghana
| | - Florian Suerland
- Department of Anatomy and Molecular Embryology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
| | - David Revuelta García
- Department of Anatomy and Molecular Embryology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
| | - Julia Kwiatkowski
- Department of Anatomy and Molecular Embryology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
| | - Ajeesh Balakrishnan-Renuka
- Department of Anatomy and Molecular Embryology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
| | - Pauline Bohne
- Department of Behavioral Neuroscience, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Bochum, Germany
| | - Marion Böing
- Department of Anatomy and Molecular Embryology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
| | - Gabriela Morosan-Puopolo
- Department of Anatomy and Molecular Embryology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
| | - Melanie D. Mark
- Department of Behavioral Neuroscience, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Bochum, Germany
| | - Beate Brand-Saberi
- Department of Anatomy and Molecular Embryology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany
- *Correspondence: Beate Brand-Saberi,
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Nassar R, Vernus B, Carnac G, Fouret G, Goustard B, Casas F, Tintignac L, Cassar-Malek I, Picard B, Seiliez I, Brioche T, Koechlin-Ramonatxo C, Bertrand-Gaday C, Hamade A, Najjar F, Chabi B, Bonnieu A. Myostatin gene inactivation increases post-mortem calpain-dependent muscle proteolysis in mice. Meat Sci 2021; 185:108726. [PMID: 34973590 DOI: 10.1016/j.meatsci.2021.108726] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/17/2021] [Accepted: 12/19/2021] [Indexed: 12/13/2022]
Abstract
Myostatin deficiency leads to extensive skeletal muscle hypertrophy, but its consequence on post-mortem muscle proteolysis is unknown. Here, we compared muscle myofibrillar protein degradation, and autophagy, ubiquitin-proteasome and Ca2+-dependent proteolysis relative to the energetic and redox status in wild-type (WT) and myostatin knock-out mice (KO) during early post-mortem storage. KO muscles showed higher degradation of myofibrillar proteins in the first 24 h after death, associated with preserved antioxidant status, compared with WT muscles. Analysis of key autophagy and ubiquitin-proteasome system markers indicated that these two pathways were not upregulated in post-mortem muscle (both genotypes), but basal autophagic flux and ATP content were lower in KO muscles. Proteasome and caspase activities were not different between WT and KO mice. Conversely, calpain activity was higher in KO muscles, concomitantly with higher troponin T and desmin degradation. Altogether, these results suggest that calpains but not the autophagy, proteasome and caspase systems, explain the difference in post-mortem muscle protein proteolysis between both genotypes.
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Affiliation(s)
- Rim Nassar
- DMEM, University of Montpellier, INRAE, Montpellier, France; Laboratoire d'Innovation thérapeutique, Lebanese University, Beyrouth, Liban
| | - Barbara Vernus
- DMEM, University of Montpellier, INRAE, Montpellier, France
| | - Gilles Carnac
- PHYMEDEXP, University of Montpellier, CNRS, INSERM, CHRU, Montpellier, France
| | - Gilles Fouret
- DMEM, University of Montpellier, INRAE, Montpellier, France
| | | | - François Casas
- DMEM, University of Montpellier, INRAE, Montpellier, France
| | - Lionel Tintignac
- Département de Biomédecine, Basel University, Basel, Switzerland
| | - Isabelle Cassar-Malek
- University Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genès-Champanelle, France
| | - Brigitte Picard
- University Clermont Auvergne, INRAE, VetAgro Sup, UMR Herbivores, F-63122 Saint-Genès-Champanelle, France
| | - Iban Seiliez
- Université de Pau et des Pays de l'Adour, E2S UPPA, INRAE, UMR1419 Nutrition Métabolisme et Aquaculture, F-64310 Saint-Pée-sur-Nivelle, France
| | - Thomas Brioche
- DMEM, University of Montpellier, INRAE, Montpellier, France
| | | | | | - Aline Hamade
- Laboratoire d'Innovation thérapeutique, Lebanese University, Beyrouth, Liban
| | - Fadia Najjar
- Laboratoire d'Innovation thérapeutique, Lebanese University, Beyrouth, Liban
| | - Béatrice Chabi
- DMEM, University of Montpellier, INRAE, Montpellier, France
| | - Anne Bonnieu
- DMEM, University of Montpellier, INRAE, Montpellier, France.
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Construction of a rAAV-SaCas9 system expressing eGFP and its application to improve muscle mass. Biotechnol Lett 2021; 43:2111-2129. [PMID: 34590222 PMCID: PMC8510912 DOI: 10.1007/s10529-021-03183-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 08/19/2021] [Indexed: 10/26/2022]
Abstract
An ideal rAAV gene editing system not only effectively edits genes at specific site, but also prevents the spread of the virus from occurring off-target or carcinogenic risks. This is important for gene editing research at specific site in vivo. We report a single rAAV containing SaCas9 and guide RNAs under the control of subtle EF1a and tRNA promoters. The capacity of rAAV was compressed, and the editing efficiency was similar to that of the classical Cas9 system in vitro and in vivo. And we inserted the sequence of the green fluorescent protein eGFP into rAAV. The number of cells infected with the rAAV and the region in which the rAAV spreads were known by the fluorescent expression of eGFP in cells. In addition, we demonstrated that myostatin gene in the thigh muscles of C57BL/10 mice was knocked out by the rAAV9-SaCas9 system to make muscle mass increased obviously. The protein eGFP into rAAV has significant implications for our indirect analysis of the editing efficiency of SaCas9 in the genome of the target tissue and reduces the harm caused by off-target editing and prevents other tissue mutations. The rAAV system has substantial potential in improving muscle mass and preventing muscle atrophy.
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Deres F, Schwartz S, Kappes-Horn K, Kornblum C, Reimann J. Early Changes in Skeletal Muscle of Young C22 Mice, A Model of Charcot-Marie-Tooth 1A. J Neuromuscul Dis 2021; 8:S283-S299. [PMID: 34459411 PMCID: PMC8673495 DOI: 10.3233/jnd-210681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background: The C22 mouse is a Charcot-Marie-Tooth 1A transgenic model with minimal axonal loss. Objective: To analyse early skeletal muscle changes resulting from this dysmyelinating neuropathy. Methods: Histology of tibialis anterior muscles of C22 mice and wild type litter mate controls for morphometric analysis and (immuno-)histochemistry for known denervation markers and candidate proteins identified by representational difference analysis (RDA) based on mRNA from the same muscles; quantitative PCR and Western blotting for confirmation of RDA findings. Results: At age 10 days, morphometry was not different between groups, while at 21 days, C22 showed significantly more small diameter fibres, indicating the onset of atrophy at an age when weakness becomes detectable. Neither (immuno-)histochemistry nor RDA detected extrajunctional expression of acetylcholine receptors by age 10 and 21 days, respectively. RDA identified some mRNA up-regulated in C22 muscles, among them at 10 days, prior to detectable weakness or atrophy, integral membrane protein 2a (Itm2a), eukaryotic initiation factor 2, subunit 2 (Eif2s2) and cytoplasmic phosphatidylinositol transfer protein 1 (Pitpnc1). However, qPCR failed to measure significant differences. In contrast, Itm2a and Eif2s2 mRNA were significantly down-regulated comparing 21 versus 10 days of age in both groups, C22 and controls. Western blotting confirmed significant down-regulation of ITM2A protein in C22 only. Conclusion: Denervation-like changes in this model develop slowly with onset of atrophy and weakness at about three weeks of age, before detection of extrajunctional acetylcholine receptors. Altered Itm2a expression seems to begin early as an increase, but becomes distinct as a decrease later.
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Affiliation(s)
- Friederike Deres
- Department of Neurology, Section of Neuromuscular Diseases, University Hospital Bonn, Germany
| | - Stephanie Schwartz
- Department of Neurology, Section of Neuromuscular Diseases, University Hospital Bonn, Germany
| | - Karin Kappes-Horn
- Department of Neurology, Section of Neuromuscular Diseases, University Hospital Bonn, Germany
| | - Cornelia Kornblum
- Department of Neurology, Section of Neuromuscular Diseases, University Hospital Bonn, Germany.,Centre for Rare Diseases, University Hospital Bonn, Germany
| | - Jens Reimann
- Department of Neurology, Section of Neuromuscular Diseases, University Hospital Bonn, Germany
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Myostatin-1 Inhibits Cell Proliferation by Inhibiting the mTOR Signal Pathway and MRFs, and Activating the Ubiquitin-Proteasomal System in Skeletal Muscle Cells of Japanese Flounder Paralichthys olivaceus. Cells 2020; 9:cells9112376. [PMID: 33138208 PMCID: PMC7692286 DOI: 10.3390/cells9112376] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 11/17/2022] Open
Abstract
Myostatin (MSTN) is a negative regulator of skeletal muscle growth and development. The mechanisms of fish MSTN involved in muscle growth are not fully understood. In the present study, knockdown and overexpression of mstn-1 was performed in cultured Japanese flounder muscle cells to investigate the molecular function and the underlying mechanism of fish MSTN-1. Results showed that mstn-1 knockdown significantly induced cell proliferation and the mRNA expression of myogenic regulatory factors (MRFs), while overexpression of mstn-1 led to a significant decrease of cell proliferation and a suppression of the MRFs mRNA expression. The overexpression of mstn-1 also significantly increased the mRNA expression of ubiquitin–proteasomal pathway of proteolysis genes including muscle RING-finger protein 1 (murf-1) by 204.1% (p = 0.024) and muscle atrophy F-box protein (mafbx) by 165.7% (p = 0.011). However, mystn-1 overexpression inhibited the activation of mTOR signal pathway and the AKT/FoxO1 pathway through decreasing phosphorylation of AKT at Ser 473 by 56.0% (p = 0.001). Meanwhile, mystn-1 overexpression increased the dephosphorylation and nuclear localization of FoxO1 by 394.9% (p = 0.005). These results demonstrate that mstn-1 in Japanese flounder has the effects of inhibiting cell proliferation and growth, and the mTOR and AKT/FoxO1 pathways participated in these biological effects.
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Sanchis-Gomar F, Lopez-Lopez S, Romero-Morales C, Maffulli N, Lippi G, Pareja-Galeano H. Neuromuscular Electrical Stimulation: A New Therapeutic Option for Chronic Diseases Based on Contraction-Induced Myokine Secretion. Front Physiol 2019; 10:1463. [PMID: 31849710 PMCID: PMC6894042 DOI: 10.3389/fphys.2019.01463] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 11/13/2019] [Indexed: 11/13/2022] Open
Abstract
Myokines are peptides known to modulate brain neuroplasticity, adipocyte metabolism, bone mineralization, endothelium repair and cell growth arrest in colon and breast cancer, among other processes. Repeated skeletal muscle contraction induces the production and secretion of myokines, which have a wide range of functions in different tissues and organs. This new role of skeletal muscle as a secretory organ means skeletal muscle contraction could be a key player in the prevention and/or management of chronic disease. However, some individuals are not capable of optimal physical exercise in terms of adequate duration, intensity or muscles involved, and therefore they may be virtually deprived of at least some of the physiological benefits induced by exercise. Neuromuscular electrical stimulation (NMES) is emerging as an effective physical exercise substitute for myokine induction. NMES is safe and efficient and has been shown to improve muscle strength, functional capacity, and quality of life. This alternative exercise modality elicits hypertrophy and neuromuscular adaptations of skeletal muscles. NMES stimulates circulating myokine secretion, promoting a cascade of endocrine, paracrine, and autocrine effects. We review the current evidence supporting NMES as an effective physical exercise substitute for inducing myokine production and its potential applications in health and disease.
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Affiliation(s)
- Fabian Sanchis-Gomar
- Department of Physiology, Faculty of Medicine, INCLIVA Biomedical Research Institute, University of Valencia, Valencia, Spain
| | - Sergio Lopez-Lopez
- Facultad de Ciencias del Deporte, Universidad Europea de Madrid, Madrid, Spain
| | | | - Nicola Maffulli
- Department of Musculoskeletal Disorders, Faculty of Medicine and Surgery, University of Salerno, Baronissi, Italy.,Centre for Sports and Exercise Medicine, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.,Guy Hilton Research Centre, School of Pharmacy and Bioengineering, Keele University, Stoke-on-Trent, United Kingdom
| | - Giuseppe Lippi
- Section of Clinical Biochemistry, University of Verona, Verona, Italy
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Tocotrienol-Rich Fraction (TRF) Treatment Promotes Proliferation Capacity of Stress-Induced Premature Senescence Myoblasts and Modulates the Renewal of Satellite Cells: Microarray Analysis. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:9141343. [PMID: 30774750 PMCID: PMC6350575 DOI: 10.1155/2019/9141343] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 10/18/2018] [Accepted: 11/12/2018] [Indexed: 12/17/2022]
Abstract
Human skeletal muscle is a vital organ involved in movement and force generation. It suffers from deterioration in mass, strength, and regenerative capacity in sarcopenia. Skeletal muscle satellite cells are involved in the regeneration process in response to muscle loss. Tocotrienol, an isomer of vitamin E, was reported to have a protective effect on cellular aging. This research is aimed at determining the modulation of tocotrienol-rich fraction (TRF) on the gene expressions of stress-induced premature senescence (SIPS) human skeletal muscle myoblasts (CHQ5B). CHQ5B cells were divided into three groups, i.e., untreated young control, SIPS control (treated with 1 mM hydrogen peroxide), and TRF-posttreated groups (24 hours of 50 μg/mL TRF treatment after SIPS induction). The differential gene expressions were assessed using microarray, GSEA, and KEGG pathway analysis. Results showed that TRF treatment significantly regulated the gene expressions, i.e., p53 (RRM2B, SESN1), ErbB (EREG, SHC1, and SHC3), and FoxO (MSTN, SMAD3) signalling pathways in the SIPS myoblasts compared to the SIPS control group (p < 0.05). TRF treatment modulated the proliferation capacity of SIPS myoblasts through regulation of ErbB (upregulation of expression of EREG, SHC1, and SHC3) and FoxO (downregulation of expression of MSTN and SMAD3) and maintaining the renewal of satellite cells through p53 signalling (upregulation of RRM2B and SESN1), MRF, cell cycle, and Wnt signalling pathways.
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9
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Gueugneau M, d'Hose D, Barbé C, de Barsy M, Lause P, Maiter D, Bindels LB, Delzenne NM, Schaeffer L, Gangloff YG, Chambon C, Coudy-Gandilhon C, Béchet D, Thissen JP. Increased Serpina3n release into circulation during glucocorticoid-mediated muscle atrophy. J Cachexia Sarcopenia Muscle 2018; 9:929-946. [PMID: 29989354 PMCID: PMC6204594 DOI: 10.1002/jcsm.12315] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 04/13/2018] [Accepted: 04/22/2018] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Glucocorticoids (GC) play a major role in muscle atrophy. As skeletal muscle is a secretory organ, characterization of the muscle secretome elicited by muscle atrophy should allow to better understand the cellular mechanisms and to identify circulating biomarkers of this condition. Our project aimed to identify the changes in the muscle secretome associated with GC-induced muscle atrophy and susceptible to translate into circulation. METHODS We have identified the GC-induced changes in the secretome of C2 C12 muscle cells by proteomic analysis, and then, we have determined how these changes translate into the circulation of mice or human subjects exposed to high concentrations of GC. RESULTS This approach led us to identify Serpina3n as one of the most markedly secreted protein in response to GC. Our original in vitro results were confirmed in vivo by an increased expression of Serpina3n in skeletal muscle (3.9-fold; P < 0.01) and in the serum (two-fold; P < 0.01) of mice treated with GC. We also observed increased levels of the human orthologue Serpina3 in the serum of Cushing's syndrome patients compared with healthy controls matched for age and sex (n = 9/group, 2.5-fold; P < 0.01). An increase of Serpina3n was also demonstrated in muscle atrophy models mediated by GC such as cancer cachexia (four-fold; P < 0.01), sepsis (12.5-fold; P < 0.001), or diabetes (two-fold; P < 0.01). In contrast, levels of Serpina3n both in skeletal muscle and in the circulation were reduced in several models of muscle hypertrophy induced by myostatin inhibition (P < 0.01). Furthermore, a cluster of data suggests that the regulation of muscle Serpina3n involves mTOR, an essential determinant of the muscle cell size. CONCLUSIONS Taken together, these data suggest that Serpina3n may represent a circulating biomarker of muscle atrophy associated to GC and, broadly, a reflection of dynamic changes in muscle mass.
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Affiliation(s)
- Marine Gueugneau
- Pole of Endocrinology, Diabetes and Nutrition, Institute of Experimental and Clinical Research, Université catholique de Louvain, Brussels, Belgium.,INRA, UMR1019, Université Clermont Auvergne, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | - Donatienne d'Hose
- Pole of Endocrinology, Diabetes and Nutrition, Institute of Experimental and Clinical Research, Université catholique de Louvain, Brussels, Belgium
| | - Caroline Barbé
- Pole of Endocrinology, Diabetes and Nutrition, Institute of Experimental and Clinical Research, Université catholique de Louvain, Brussels, Belgium
| | - Marie de Barsy
- Pole of Endocrinology, Diabetes and Nutrition, Institute of Experimental and Clinical Research, Université catholique de Louvain, Brussels, Belgium
| | - Pascale Lause
- Pole of Endocrinology, Diabetes and Nutrition, Institute of Experimental and Clinical Research, Université catholique de Louvain, Brussels, Belgium
| | - Dominique Maiter
- Pole of Endocrinology, Diabetes and Nutrition, Institute of Experimental and Clinical Research, Université catholique de Louvain, Brussels, Belgium
| | - Laure B Bindels
- Metabolism and Nutrition Research Group, Louvain Drug Research Institute (LDRI), Université catholique de Louvain, Brussels, Belgium
| | - Nathalie M Delzenne
- Metabolism and Nutrition Research Group, Louvain Drug Research Institute (LDRI), Université catholique de Louvain, Brussels, Belgium
| | - Laurent Schaeffer
- INMG, CNRS, UMR 5310, INSERM U1217, LBMC, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Yann-Gaël Gangloff
- INMG, CNRS, UMR 5310, INSERM U1217, LBMC, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Christophe Chambon
- INRA, Plateforme d'Exploration du Métabolisme Composante Protéomique, Saint Genès Champanelle, France
| | - Cécile Coudy-Gandilhon
- INRA, UMR1019, Université Clermont Auvergne, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | - Daniel Béchet
- INRA, UMR1019, Université Clermont Auvergne, UNH, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | - Jean-Paul Thissen
- Pole of Endocrinology, Diabetes and Nutrition, Institute of Experimental and Clinical Research, Université catholique de Louvain, Brussels, Belgium
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Deng Z, Luo P, Lai W, Song T, Peng J, Wei HK. Myostatin inhibits eEF2K-eEF2 by regulating AMPK to suppress protein synthesis. Biochem Biophys Res Commun 2017; 494:278-284. [DOI: 10.1016/j.bbrc.2017.10.040] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 10/07/2017] [Indexed: 02/07/2023]
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11
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Hennebry A, Oldham J, Shavlakadze T, Grounds MD, Sheard P, Fiorotto ML, Falconer S, Smith HK, Berry C, Jeanplong F, Bracegirdle J, Matthews K, Nicholas G, Senna-Salerno M, Watson T, McMahon CD. IGF1 stimulates greater muscle hypertrophy in the absence of myostatin in male mice. J Endocrinol 2017; 234:187-200. [PMID: 28533420 DOI: 10.1530/joe-17-0032] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 05/22/2017] [Indexed: 01/02/2023]
Abstract
Insulin-like growth factors (IGFs) and myostatin have opposing roles in regulating the growth and size of skeletal muscle, with IGF1 stimulating, and myostatin inhibiting, growth. However, it remains unclear whether these proteins have mutually dependent, or independent, roles. To clarify this issue, we crossed myostatin null (Mstn-/-) mice with mice overexpressing Igf1 in skeletal muscle (Igf1+) to generate six genotypes of male mice; wild type (Mstn+/+ ), Mstn+/-, Mstn-/-, Mstn+/+:Igf1+, Mstn+/-:Igf1+ and Mstn-/-:Igf1+ Overexpression of Igf1 increased the mass of mixed fibre type muscles (e.g. Quadriceps femoris) by 19% over Mstn+/+ , 33% over Mstn+/- and 49% over Mstn-/- (P < 0.001). By contrast, the mass of the gonadal fat pad was correspondingly reduced with the removal of Mstn and addition of Igf1 Myostatin regulated the number, while IGF1 regulated the size of myofibres, and the deletion of Mstn and Igf1+ independently increased the proportion of fast type IIB myosin heavy chain isoforms in T. anterior (up to 10% each, P < 0.001). The abundance of AKT and rpS6 was increased in muscles of Mstn-/-mice, while phosphorylation of AKTS473 was increased in Igf1+mice (Mstn+/+:Igf1+, Mstn+/-:Igf1+ and Mstn-/-:Igf1+). Our results demonstrate that a greater than additive effect is observed on the growth of skeletal muscle and in the reduction of body fat when myostatin is absent and IGF1 is in excess. Finally, we show that myostatin and IGF1 regulate skeletal muscle size, myofibre type and gonadal fat through distinct mechanisms that involve increasing the total abundance and phosphorylation status of AKT and rpS6.
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Affiliation(s)
| | | | - Tea Shavlakadze
- School of AnatomyPhysiology & Human Biology, The University of Western Australia, Crawley, Western Australia, Australia
| | - Miranda D Grounds
- School of AnatomyPhysiology & Human Biology, The University of Western Australia, Crawley, Western Australia, Australia
| | - Philip Sheard
- Department of PhysiologyUniversity of Otago, Dunedin, New Zealand
| | - Marta L Fiorotto
- USDA/ARS Children's Nutrition Research CenterBaylor College of Medicine, Houston, Texas, USA
| | | | - Heather K Smith
- Department of Exercise SciencesUniversity of Auckland, Auckland, New Zealand
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Wall BT, Burd NA, Franssen R, Gorissen SHM, Snijders T, Senden JM, Gijsen AP, van Loon LJC. Presleep protein ingestion does not compromise the muscle protein synthetic response to protein ingested the following morning. Am J Physiol Endocrinol Metab 2016; 311:E964-E973. [PMID: 27780822 DOI: 10.1152/ajpendo.00325.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/11/2016] [Accepted: 10/24/2016] [Indexed: 11/22/2022]
Abstract
Protein ingestion before sleep augments postexercise muscle protein synthesis during overnight recovery. It is unknown whether postexercise and presleep protein consumption modulates postprandial protein handling and myofibrillar protein synthetic responses the following morning. Sixteen healthy young (24 ± 1 yr) men performed unilateral resistance-type exercise (contralateral leg acting as a resting control) at 2000. Participants ingested 20 g of protein immediately after exercise plus 60 g of protein presleep (PRO group; n = 8) or equivalent boluses of carbohydrate (CON; n = 8). The subsequent morning participants received primed, continuous infusions of l-[ring-2H5]phenylalanine and l-[1-13C]leucine combined with ingestion of 20 g intrinsically l-[1-13C]phenylalanine- and l-[1-13C]leucine-labeled protein to assess postprandial protein handling and myofibrillar protein synthesis in the rested and exercised leg in CON and PRO. Exercise increased postabsorptive myofibrillar protein synthesis rates the subsequent day (P < 0.001), with no differences between CON and PRO. Protein ingested in the morning increased myofibrillar protein synthesis in both the exercised and rested leg (P < 0.01), with no differences between treatments. Myofibrillar protein bound l-[1-13C]phenylalanine enrichments were greater in the exercised (0.016 ± 0.002 and 0.015 ± 0.002 MPE in CON and PRO, respectively) vs. rested (0.010 ± 0.002 and 0.009 ± 0.002 MPE in CON and PRO, respectively) leg (P < 0.05), with no differences between treatments (P > 0.05). The additive effects of resistance-type exercise and protein ingestion on myofibrillar protein synthesis persist for more than 12 h after exercise and are not modulated by protein consumption during acute postexercise recovery. This work provides evidence of an extended window of opportunity where presleep protein supplementation can be an effective nutrient timing strategy to optimize skeletal muscle reconditioning.
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Affiliation(s)
- Benjamin T Wall
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Nicholas A Burd
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Rinske Franssen
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Stefan H M Gorissen
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Tim Snijders
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Joan M Senden
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Annemie P Gijsen
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Luc J C van Loon
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
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Grassot V, Bouchatal A, Da Silva A, Chantepie S, Papy-Garcia D, Maftah A, Gallet PF, Petit JM. Heparan sulfates and the decrease of N-glycans promote early adipogenic differentiation rather than myogenesis of murine myogenic progenitor cells. Differentiation 2016; 93:15-26. [PMID: 27689814 DOI: 10.1016/j.diff.2016.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 08/05/2016] [Accepted: 08/29/2016] [Indexed: 12/25/2022]
Abstract
In vitro, extracted muscle satellite cells, called myogenic progenitor cells, can differentiate either in myotubes or preadipocytes, depending on environmental factors and the medium. Transcriptomic analyses on glycosylation genes during satellite cells differentiation into myotubes showed that 31 genes present a significant variation of expression at the early stages of murine myogenic progenitor cells (MPC) differentiation. In the present study, we analyzed the expression of 383 glycosylation related genes during murine MPC differentiation into preadipocytes and compared the data to those previously obtained during their differentiation into myotubes. Fifty-six glycosylation related genes are specifically modified in their expression during early adipogenesis. The variations correspond mainly to: a decrease of N-glycans, and of alpha (2,3) and (2,6) linked sialic acids, and to a high level of heparan sulfates. A high amount of TGF-β1 in extracellular media during early adipogenesis was also observed. It seems that the increases of heparan sulfates and TGF-β1 favor pre-adipogenic differentition of MPC and possibly prevent their myogenic differentiation.
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Affiliation(s)
- Vincent Grassot
- INRA, UMR 1061, F-87060 Limoges, France; Université de Limoges, Faculté des Sciences et Techniques, Unité de Génétique Moléculaire Animale, UGMA, F-87060 Limoges, France.
| | - Amel Bouchatal
- INRA, UMR 1061, F-87060 Limoges, France; Université de Limoges, Faculté des Sciences et Techniques, Unité de Génétique Moléculaire Animale, UGMA, F-87060 Limoges, France.
| | - Anne Da Silva
- INRA, UMR 1061, F-87060 Limoges, France; Université de Limoges, Faculté des Sciences et Techniques, Unité de Génétique Moléculaire Animale, UGMA, F-87060 Limoges, France.
| | - Sandrine Chantepie
- CNRS, EAC 7149, F-94000 Créteil, France; Université Paris Est Créteil, Laboratoire Croissance, Régénération, Réparation et Régénération Tissulaires, CRRET, F-94000 Créteil, France.
| | - Dulce Papy-Garcia
- CNRS, EAC 7149, F-94000 Créteil, France; Université Paris Est Créteil, Laboratoire Croissance, Régénération, Réparation et Régénération Tissulaires, CRRET, F-94000 Créteil, France.
| | - Abderrahman Maftah
- INRA, UMR 1061, F-87060 Limoges, France; Université de Limoges, Faculté des Sciences et Techniques, Unité de Génétique Moléculaire Animale, UGMA, F-87060 Limoges, France.
| | - Paul-François Gallet
- INRA, UMR 1061, F-87060 Limoges, France; Université de Limoges, Faculté des Sciences et Techniques, Unité de Génétique Moléculaire Animale, UGMA, F-87060 Limoges, France.
| | - Jean-Michel Petit
- INRA, UMR 1061, F-87060 Limoges, France; Université de Limoges, Faculté des Sciences et Techniques, Unité de Génétique Moléculaire Animale, UGMA, F-87060 Limoges, France.
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Protein breakdown in cancer cachexia. Semin Cell Dev Biol 2016; 54:11-9. [DOI: 10.1016/j.semcdb.2015.11.002] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 11/04/2015] [Indexed: 12/22/2022]
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15
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de Rooy C, Grossmann M, Zajac JD, Cheung AS. Targeting muscle signaling pathways to minimize adverse effects of androgen deprivation. Endocr Relat Cancer 2016; 23:R15-26. [PMID: 26432470 DOI: 10.1530/erc-15-0232] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/02/2015] [Indexed: 01/05/2023]
Abstract
Androgen deprivation therapy (ADT) is a highly effective treatment used in ∼30% of men with prostate cancer. Adverse effects of ADT on muscle are significant with consistent losses in muscle mass. However, effects of ADT on muscle strength and physical function, of most relevance to the patient, are less well understood. This is in part due to the fact that muscle effects of ADT at the cellular, genetic and protein level, critical to the understanding of the pathophysiology of sarcopenia, have come into focus only recently. This review highlights the complexity of androgen-dependent signaling in muscle with an emphasis on recent findings in the regulation of muscle growth and muscle atrophy pathways. Furthermore, the effects of ADT and testosterone on skeletal muscle histology, gene expression and protein transcription are discussed. A better mechanistic understanding of the regulation of muscle mass and function by androgens should not only pave the way for developing targeted promyogenic interventions for men with prostate cancer receiving ADT but also may have wider implications for age-associated sarcopenia in the general population.
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Affiliation(s)
- Casey de Rooy
- Department of MedicineUniversity of Melbourne, Heidelberg, Victoria, AustraliaDepartment of EndocrinologyAustin Health, Studley Road Heidelberg, Victoria, 3084, Australia
| | - Mathis Grossmann
- Department of MedicineUniversity of Melbourne, Heidelberg, Victoria, AustraliaDepartment of EndocrinologyAustin Health, Studley Road Heidelberg, Victoria, 3084, Australia Department of MedicineUniversity of Melbourne, Heidelberg, Victoria, AustraliaDepartment of EndocrinologyAustin Health, Studley Road Heidelberg, Victoria, 3084, Australia
| | - Jeffrey D Zajac
- Department of MedicineUniversity of Melbourne, Heidelberg, Victoria, AustraliaDepartment of EndocrinologyAustin Health, Studley Road Heidelberg, Victoria, 3084, Australia Department of MedicineUniversity of Melbourne, Heidelberg, Victoria, AustraliaDepartment of EndocrinologyAustin Health, Studley Road Heidelberg, Victoria, 3084, Australia
| | - Ada S Cheung
- Department of MedicineUniversity of Melbourne, Heidelberg, Victoria, AustraliaDepartment of EndocrinologyAustin Health, Studley Road Heidelberg, Victoria, 3084, Australia Department of MedicineUniversity of Melbourne, Heidelberg, Victoria, AustraliaDepartment of EndocrinologyAustin Health, Studley Road Heidelberg, Victoria, 3084, Australia
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16
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Smith RC, Cramer MS, Mitchell PJ, Capen A, Huber L, Wang R, Myers L, Jones BE, Eastwood BJ, Ballard D, Hanson J, Credille KM, Wroblewski VJ, Lin BK, Heuer JG. Myostatin Neutralization Results in Preservation of Muscle Mass and Strength in Preclinical Models of Tumor-Induced Muscle Wasting. Mol Cancer Ther 2015; 14:1661-70. [PMID: 25908685 DOI: 10.1158/1535-7163.mct-14-0681] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 04/17/2015] [Indexed: 11/16/2022]
Abstract
Skeletal muscle wasting occurs in a great majority of cancer patients with advanced disease and is associated with a poor prognosis and decreased survival. Myostatin functions as a negative regulator of skeletal muscle mass and has recently become a therapeutic target for reducing the loss of skeletal muscle and strength associated with clinical myopathies. We generated neutralizing antibodies to myostatin to test their potential use as therapeutic agents to attenuate the skeletal muscle wasting due to cancer. We show that our neutralizing antimyostatin antibodies significantly increase body weight, skeletal muscle mass, and strength in non-tumor-bearing mice with a concomitant increase in mean myofiber area. The administration of these neutralizing antibodies in two preclinical models of cancer-induced muscle wasting (C26 colon adenocarcinoma and PC3 prostate carcinoma) resulted in a significant attenuation of the loss of muscle mass and strength with no effect on tumor growth. We also show that the skeletal muscle mass- and strength-preserving effect of the antibodies is not affected by the coadministration of gemcitabine, a common chemotherapeutic agent, in both non-tumor-bearing mice and mice bearing C26 tumors. In addition, we show that myostatin neutralization with these antibodies results in the preservation of skeletal muscle mass following reduced caloric intake, a common comorbidity associated with advanced cancer. Our findings support the use of neutralizing antimyostatin antibodies as potential therapeutics for cancer-induced muscle wasting.
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Affiliation(s)
- Rosamund C Smith
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
| | - Martin S Cramer
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Pamela J Mitchell
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Andrew Capen
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Lysiane Huber
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Rong Wang
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Laura Myers
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Bryan E Jones
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Brian J Eastwood
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Darryl Ballard
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Jeff Hanson
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Kelly M Credille
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Victor J Wroblewski
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Boris K Lin
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Josef G Heuer
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
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Rodriguez J, Vernus B, Chelh I, Cassar-Malek I, Gabillard JC, Hadj Sassi A, Seiliez I, Picard B, Bonnieu A. Myostatin and the skeletal muscle atrophy and hypertrophy signaling pathways. Cell Mol Life Sci 2014; 71:4361-71. [PMID: 25080109 PMCID: PMC11113773 DOI: 10.1007/s00018-014-1689-x] [Citation(s) in RCA: 259] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 07/16/2014] [Accepted: 07/17/2014] [Indexed: 12/16/2022]
Abstract
Myostatin, a member of the transforming growth factor-β superfamily, is a potent negative regulator of skeletal muscle growth and is conserved in many species, from rodents to humans. Myostatin inactivation can induce skeletal muscle hypertrophy, while its overexpression or systemic administration causes muscle atrophy. As it represents a potential target for stimulating muscle growth and/or preventing muscle wasting, myostatin regulation and functions in the control of muscle mass have been extensively studied. A wealth of data strongly suggests that alterations in skeletal muscle mass are associated with dysregulation in myostatin expression. Moreover, myostatin plays a central role in integrating/mediating anabolic and catabolic responses. Myostatin negatively regulates the activity of the Akt pathway, which promotes protein synthesis, and increases the activity of the ubiquitin-proteasome system to induce atrophy. Several new studies have brought new information on how myostatin may affect both ribosomal biogenesis and translation efficiency of specific mRNA subclasses. In addition, although myostatin has been identified as a modulator of the major catabolic pathways, including the ubiquitin-proteasome and the autophagy-lysosome systems, the underlying mechanisms are only partially understood. The goal of this review is to highlight outstanding questions about myostatin-mediated regulation of the anabolic and catabolic signaling pathways in skeletal muscle. Particular emphasis has been placed on (1) the cross-regulation between myostatin, the growth-promoting pathways and the proteolytic systems; (2) how myostatin inhibition leads to muscle hypertrophy; and (3) the regulation of translation by myostatin.
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Affiliation(s)
- J. Rodriguez
- INRA, UMR866 Dynamique Musculaire Et Métabolisme, Université Montpellier 1, Université Montpellier 2, 2 Place Viala, 34060 Montpellier, France
| | - B. Vernus
- INRA, UMR866 Dynamique Musculaire Et Métabolisme, Université Montpellier 1, Université Montpellier 2, 2 Place Viala, 34060 Montpellier, France
| | - I. Chelh
- INRA, VetAgro Sup, UMR1213 Herbivores, 63122 Saint-Genès-Champanelle, France
| | - I. Cassar-Malek
- INRA, VetAgro Sup, UMR1213 Herbivores, 63122 Saint-Genès-Champanelle, France
| | - J. C. Gabillard
- INRA, UR1037, Fish Physiology and Genomics, Campus de Beaulieu, 35000 Rennes, France
| | - A. Hadj Sassi
- INRA-USC2009, Université Bordeaux 1, Avenue des Facultés, 33405 Talence, France
| | - I. Seiliez
- INRA, UR1067 Nutrition, Métabolisme, Aquaculture, 64310 Saint-Pée-sur-Nivelle, France
| | - B. Picard
- INRA, VetAgro Sup, UMR1213 Herbivores, 63122 Saint-Genès-Champanelle, France
| | - A. Bonnieu
- INRA, UMR866 Dynamique Musculaire Et Métabolisme, Université Montpellier 1, Université Montpellier 2, 2 Place Viala, 34060 Montpellier, France
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18
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Singh R, Braga M, Pervin S. Regulation of brown adipocyte metabolism by myostatin/follistatin signaling. Front Cell Dev Biol 2014; 2:60. [PMID: 25364764 PMCID: PMC4207030 DOI: 10.3389/fcell.2014.00060] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 09/26/2014] [Indexed: 12/11/2022] Open
Abstract
Obesity develops from perturbations of cellular bioenergetics, when energy uptake exceeds energy expenditure, and represents a major risk factor for the development of type 2 diabetes, dyslipidemia, cardiovascular disease, cancer, and other conditions. Brown adipose tissue (BAT) has long been known to dissipate energy as heat and contribute to energy expenditure, but its presence and physiological role in adult human physiology has been questioned for years. Recent demonstrations of metabolically active brown fat depots in adult humans have revolutionized current therapeutic approaches for obesity-related diseases. The balance between white adipose tissue (WAT) and BAT affects the systemic energy balance and is widely believed to be the key determinant in the development of obesity and related metabolic diseases. Members of the transforming growth factor-beta (TGF-β) superfamily play an important role in regulating overall energy homeostasis by modulation of brown adipocyte characteristics. Inactivation of TGF-β/Smad3/myostatin (Mst) signaling promotes browning of white adipocytes, increases mitochondrial biogenesis and protects mice from diet-induced obesity, suggesting the need for development of a novel class of TGF-β/Mst antagonists for the treatment of obesity and related metabolic diseases. We recently described an important role of follistatin (Fst), a soluble glycoprotein that is known to bind and antagonize Mst actions, during brown fat differentiation and the regulation of cellular metabolism. Here we highlight various investigations performed using different in vitro and in vivo models to support the contention that targeting TGF-β/Mst signaling enhances brown adipocyte functions and regulates energy balance, reducing insulin resistance, and curbing the development of obesity and diabetes.
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Affiliation(s)
- Rajan Singh
- Division of Endocrinology and Metabolism, Charles R. Drew University of Medicine and Science Los Angeles, CA, USA ; Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA Los Angeles, CA, USA
| | - Melissa Braga
- Division of Endocrinology and Metabolism, Charles R. Drew University of Medicine and Science Los Angeles, CA, USA ; Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA Los Angeles, CA, USA
| | - Shehla Pervin
- Division of Endocrinology and Metabolism, Charles R. Drew University of Medicine and Science Los Angeles, CA, USA ; Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA Los Angeles, CA, USA
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Sartori R, Gregorevic P, Sandri M. TGFβ and BMP signaling in skeletal muscle: potential significance for muscle-related disease. Trends Endocrinol Metab 2014; 25:464-71. [PMID: 25042839 DOI: 10.1016/j.tem.2014.06.002] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 06/09/2014] [Accepted: 06/10/2014] [Indexed: 01/07/2023]
Abstract
The transforming growth factor beta (TGFβ) superfamily comprises a large number of secreted proteins that regulate various fundamental biological processes underlying embryonic development and the postnatal regulation of many cell types and organs. Sequence similarities define two ligand subfamilies: the TGFβ/activin subfamily and the bone morphogenetic protein (BMP) subfamily. The discovery that myostatin, a member of the TGFβ/activin subfamily, negatively controls muscle mass attracted attention to this pathway. However, recent findings of a positive role for BMP-mediated signaling in muscle have challenged the model of how the TGFβ network regulates skeletal muscle phenotype. This review illustrates how this complex network integrates crosstalk among members of the TGFβ superfamily and downstream signaling elements to regulate muscle in health and disease.
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Affiliation(s)
- Roberta Sartori
- Dulbecco Telethon Institute, Venetian Institute of Molecular Medicine, 35129 Padova, Italy; Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy
| | - Paul Gregorevic
- Division of Cell Signaling and Metabolism, Baker IDI Heart and Diabetes Institute, Melbourne 3004, Australia
| | - Marco Sandri
- Dulbecco Telethon Institute, Venetian Institute of Molecular Medicine, 35129 Padova, Italy; Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; Telethon Institute of Genetics and Medicine (TIGEM), 80131 Napoli, Italy.
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Grassot V, Da Silva A, Saliba J, Maftah A, Dupuy F, Petit JM. Highlights of glycosylation and adhesion related genes involved in myogenesis. BMC Genomics 2014; 15:621. [PMID: 25051993 PMCID: PMC4223822 DOI: 10.1186/1471-2164-15-621] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 07/14/2014] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Myogenesis is initiated by myoblast differentiation and fusion to form myotubes and muscle fibres. A population of myoblasts, known as satellite cells, is responsible for post-natal growth of muscle and for its regeneration. This differentiation requires many changes in cell behaviour and its surrounding environment. These modifications are tightly regulated over time and can be characterized through the study of changes in gene expression associated with this process. During the initial myogenesis steps, using the myoblast cell line C2C12 as a model, Janot et al. (2009) showed significant variations in expression for genes involved in pathways of glycolipid synthesis. In this study we used murine satellite cells (MSC) and their ability to differentiate into myotubes or early fat storage cells to select glycosylation related genes whose variation of expression is myogenesis specific. RESULTS The comparison of variant genes in both MSC differentiation pathways identified 67 genes associated with myogenesis. Comparison with data obtained for C2C12 revealed that only 14 genes had similar expression profiles in both cell types and that 17 genes were specifically regulated in MSC. Results were validated statistically by without a priori clustering. Classification according to protein function encoded by these 31 genes showed that the main regulated cellular processes during this differentiation were (i) remodeling of the extracellular matrix, particularly, sulfated structures, (ii) down-regulation of O-mannosyl glycan biosynthesis, and (iii) an increase in adhesion protein expression. A functional study was performed on Itga11 and Chst5 encoding two highly up-regulated proteins. The inactivation of Chst5 by specific shRNA delayed the fusion of MSC. By contrast, the inactivation of Itga11 by specific shRNA dramatically decreased the fusion ability of MSC. This result was confirmed by neutralization of Itga11 product by specific antibodies. CONCLUSIONS Our screening method detected 31 genes specific for myogenic differentiation out of the 383 genes studied. According to their function, interaction networks of the products of these selected genes converged to cell fusion. Functional studies on Itga11 and Chst5 demonstrated the robustness of this screening.
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Affiliation(s)
- Vincent Grassot
- INRA, UMR 1061 Unité de Génétique Moléculaire Animale, Université de Limoges, Faculté des Sciences et Techniques, 123 Avenue A. Thomas, Limoges 87060, France
| | - Anne Da Silva
- INRA, UMR 1061 Unité de Génétique Moléculaire Animale, Université de Limoges, Faculté des Sciences et Techniques, 123 Avenue A. Thomas, Limoges 87060, France
| | - James Saliba
- INRA, UMR 1061 Unité de Génétique Moléculaire Animale, Université de Limoges, Faculté des Sciences et Techniques, 123 Avenue A. Thomas, Limoges 87060, France
| | - Abderrahman Maftah
- INRA, UMR 1061 Unité de Génétique Moléculaire Animale, Université de Limoges, Faculté des Sciences et Techniques, 123 Avenue A. Thomas, Limoges 87060, France
| | - Fabrice Dupuy
- INRA, UMR 1061 Unité de Génétique Moléculaire Animale, Université de Limoges, Faculté des Sciences et Techniques, 123 Avenue A. Thomas, Limoges 87060, France
| | - Jean-Michel Petit
- INRA, UMR 1061 Unité de Génétique Moléculaire Animale, Université de Limoges, Faculté des Sciences et Techniques, 123 Avenue A. Thomas, Limoges 87060, France
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21
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Goodman CA, Hornberger TA. New roles for Smad signaling and phosphatidic acid in the regulation of skeletal muscle mass. F1000PRIME REPORTS 2014; 6:20. [PMID: 24765525 PMCID: PMC3974568 DOI: 10.12703/p6-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Skeletal muscle is essential for normal bodily function and the loss of skeletal muscle (i.e. muscle atrophy/wasting) can have a major impact on mobility, whole-body metabolism, disease resistance, and quality of life. Thus, there is a clear need for the development of therapies that can prevent the loss, or increase, of skeletal muscle mass. However, in order to develop such therapies, we will first have to develop a thorough understanding of the molecular mechanisms that regulate muscle mass. Fortunately, our knowledge is rapidly advancing, and in this review, we will summarize recent studies that have expanded our understanding of the roles that Smad signaling and the synthesis of phosphatidic acid play in the regulation of skeletal muscle mass.
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22
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Wall BT, Dirks ML, Snijders T, Senden JMG, Dolmans J, van Loon LJC. Substantial skeletal muscle loss occurs during only 5 days of disuse. Acta Physiol (Oxf) 2014; 210:600-11. [PMID: 24168489 DOI: 10.1111/apha.12190] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 07/31/2013] [Accepted: 10/24/2013] [Indexed: 11/29/2022]
Abstract
AIM The impact of disuse on the loss of skeletal muscle mass and strength has been well documented. Given that most studies have investigated muscle atrophy after more than 2 weeks of disuse, few data are available on the impact of shorter periods of disuse. We assessed the impact of 5 and 14 days of disuse on skeletal muscle mass, strength and associated intramuscular molecular signalling responses. METHODS Twenty-four healthy, young (23 ± 1 year) males were subjected to either 5 (n = 12) or 14 (n = 12) days of one-legged knee immobilization using a full leg cast. Before and immediately after the immobilization period, quadriceps muscle cross-sectional area (CSA), leg lean mass and muscle strength were assessed, and biopsies were collected from the vastus lateralis. RESULTS Quadriceps muscle CSA declined from baseline by 3.5 ± 0.5 (P < 0.0001) and 8.4 ± 2.8% (P < 0.001), leg lean mass was reduced by 1.4 ± 0.7 (P = 0.07) and 3.1 ± 0.7% (P < 0.01) and strength was decreased by 9.0 ± 2.3 (P < 0.0001) and 22.9 ± 2.6% (P < 0.001) following 5 and 14 days of immobilization respectively. Muscle myostatin mRNA expression doubled following immobilization (P < 0.05) in both groups, while the myostatin precursor isoform protein content decreased after 14 days only (P < 0.05). Muscle MAFBx mRNA expression increased from baseline by a similar magnitude following either 5 or 14 days of disuse, whereas MuRF1 mRNA expression had increased significantly only after 5 days. CONCLUSION We conclude that even short periods of muscle disuse can cause substantial loss of skeletal muscle mass and strength and are accompanied by an early catabolic molecular signalling response.
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Affiliation(s)
- B. T. Wall
- Department of Human Movement Sciences; NUTRIM School for Nutrition; Toxicology and Metabolism Maastricht University Medical Centre; Maastricht the Netherlands
| | - M. L. Dirks
- Department of Human Movement Sciences; NUTRIM School for Nutrition; Toxicology and Metabolism Maastricht University Medical Centre; Maastricht the Netherlands
| | - T. Snijders
- Department of Human Movement Sciences; NUTRIM School for Nutrition; Toxicology and Metabolism Maastricht University Medical Centre; Maastricht the Netherlands
| | - J. M. G. Senden
- Department of Human Movement Sciences; NUTRIM School for Nutrition; Toxicology and Metabolism Maastricht University Medical Centre; Maastricht the Netherlands
| | - J. Dolmans
- Department of Surgery; Maastricht University Medical Centre; Maastricht the Netherlands
| | - L. J. C. van Loon
- Department of Human Movement Sciences; NUTRIM School for Nutrition; Toxicology and Metabolism Maastricht University Medical Centre; Maastricht the Netherlands
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23
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Muscle disuse atrophy is not accompanied by changes in skeletal muscle satellite cell content. Clin Sci (Lond) 2013; 126:557-66. [DOI: 10.1042/cs20130295] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Two weeks of muscle disuse led to a loss in muscle mass and strength. The loss in muscle mass was attributed to both type I and type II muscle fibre atrophy, and was not accompanied by a decline in satellite cell content.
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24
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Smith RC, Lin BK. Myostatin inhibitors as therapies for muscle wasting associated with cancer and other disorders. Curr Opin Support Palliat Care 2013; 7:352-60. [PMID: 24157714 PMCID: PMC3819341 DOI: 10.1097/spc.0000000000000013] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW This review summarizes recent progress in the development of myostatin inhibitors for the treatment of muscle wasting disorders. It also focuses on findings in myostatin biology that may have implications for the development of antimyostatin therapies. RECENT FINDINGS There has been progress in evaluating antimyostatin therapies in animal models of muscle wasting disorders. Some programs have progressed into clinical development with initial results showing positive impact on muscle volume.In normal mice myostatin deficiency results in enlarged muscles with increased total force but decreased specific force (total force/total mass). An increase in myofibrillar protein synthesis without concomitant satellite cell proliferation and fusion leads to muscle hypertrophy with unchanged myonuclear number. A specific force reduction is not observed when atrophied muscle, the predominant therapeutic target of myostatin inhibitor therapy, is made myostatindeficient.Myostatin has been shown to be expressed by a number of tumor cell lines in mice and man. SUMMARY Myostatin inhibition remains a promising therapeutic strategy for a range of muscle wasting disorders.
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Affiliation(s)
- Rosamund C Smith
- aBiotechnology Discovery Research bOncology Business Unit, Eli Lilly and Company
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25
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Goodman CA, McNally RM, Hoffmann FM, Hornberger TA. Smad3 induces atrogin-1, inhibits mTOR and protein synthesis, and promotes muscle atrophy in vivo. Mol Endocrinol 2013; 27:1946-57. [PMID: 24002653 DOI: 10.1210/me.2013-1194] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Myostatin, a member of the TGF superfamily, is sufficient to induce skeletal muscle atrophy. Myostatin-induced atrophy is associated with increases in E3-ligase atrogin-1 expression and protein degradation and decreases in Akt/mechanistic target of rapamycin (mTOR) signaling and protein synthesis. Myostatin signaling activates the transcription factor Smad3 (Small Mothers Against Decapentaplegic), which has been shown to be necessary for myostatin-induced atrogin-1 expression and atrophy; however, it is not known whether Smad3 is sufficient to induce these events or whether Smad3 simply plays a permissive role. Thus, the aim of this study was to address these questions with an in vivo model. To accomplish this goal, in vivo transfection of plasmid DNA was used to create transient transgenic mouse skeletal muscles, and our results show for the first time that Smad3 expression is sufficient to stimulate atrogin-1 promoter activity, inhibit Akt/mTOR signaling and protein synthesis, and induce muscle fiber atrophy. Moreover, we propose that Akt/mTOR signaling is inhibited by a Smad3-induced decrease in microRNA-29 (miR-29) expression and a subsequent increase in the translation of phosphatase and tensin homolog (PTEN) mRNA. Smad3 is also sufficient to inhibit peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) promoter activity and to increase FoxO (Forkhead Box Protein, Subclass O)-mediated signaling and the promoter activity of plasminogen activator inhibitor 1 (PAI-1). Combined, this study provides the first evidence that Smad3 is sufficient to regulate many of the events associated with myostatin-induced atrophy and therefore suggests that Smad3 signaling may be a viable target for therapies aimed at preventing myostatin-induced muscle atrophy.
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Affiliation(s)
- Craig A Goodman
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53706.
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26
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Glucocorticoid-induced skeletal muscle atrophy. Int J Biochem Cell Biol 2013; 45:2163-72. [PMID: 23806868 DOI: 10.1016/j.biocel.2013.05.036] [Citation(s) in RCA: 398] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Revised: 05/27/2013] [Accepted: 05/29/2013] [Indexed: 12/11/2022]
Abstract
Many pathological states characterized by muscle atrophy (e.g., sepsis, cachexia, starvation, metabolic acidosis and severe insulinopenia) are associated with an increase in circulating glucocorticoids (GC) levels, suggesting that GC could trigger the muscle atrophy observed in these conditions. GC-induced muscle atrophy is characterized by fast-twitch, glycolytic muscles atrophy illustrated by decreased fiber cross-sectional area and reduced myofibrillar protein content. GC-induced muscle atrophy results from increased protein breakdown and decreased protein synthesis. Increased muscle proteolysis, in particular through the activation of the ubiquitin proteasome and the lysosomal systems, is considered to play a major role in the catabolic action of GC. The stimulation by GC of these two proteolytic systems is mediated through the increased expression of several Atrogenes ("genes involved in atrophy"), such as FOXO, Atrogin-1, and MuRF-1. The inhibitory effect of GC on muscle protein synthesis is thought to result mainly from the inhibition of the mTOR/S6 kinase 1 pathway. These changes in muscle protein turnover could be explained by changes in the muscle production of two growth factors, namely Insulin-like Growth Factor (IGF)-I, a muscle anabolic growth factor and Myostatin, a muscle catabolic growth factor. This review will discuss the recent progress made in the understanding of the mechanisms involved in GC-induced muscle atrophy and consider the implications of these advancements in the development of new therapeutic approaches for treating GC-induced myopathy. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.
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27
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Seiliez I, Taty Taty GC, Bugeon J, Dias K, Sabin N, Gabillard JC. Myostatin induces atrophy of trout myotubes through inhibiting the TORC1 signaling and promoting Ubiquitin-Proteasome and Autophagy-Lysosome degradative pathways. Gen Comp Endocrinol 2013; 186:9-15. [PMID: 23458288 DOI: 10.1016/j.ygcen.2013.02.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 02/04/2013] [Accepted: 02/14/2013] [Indexed: 10/27/2022]
Abstract
Myostatin (MSTN) is well known as a potent inhibitor of muscle growth in mammals and has been shown to both inhibit the growth promoting TORC1 signaling pathway and promote Ubiquitin-Proteasomal and Autophagy-Lysosomal degradative routes. In contrast, in non-mammalian species, despite high structural conservation of MSTN sequence, functional conservation is only assumed. Here, we show that treatment of cultured trout myotubes with human recombinant MSTN (huMSTN) resulted in a significant decrease of their diameter by up to 20%, validating the use of heterologous huMSTN in our in vitro model to monitor the processes by which this growth factor promotes muscle wasting in fish. Accordingly, huMSTN stimulation prevented the full activation by IGF1 of the TORC1 signaling pathway, as revealed by the analysis of the phosphorylation status of 4E-BP1. Moreover, the levels of the proteasome-dependent protein Atrogin1 exhibited an increase in huMSTN treated cells. Likewise, we observed a stimulatory effect of huMSTN treatment on the levels of LC3-II, the more reliable marker of the Autophagy-Lysosomal degradative system. Overall, these results show for the first time in a piscine species the effect of MSTN on several atrophic and hypertrophic pathways and support a functional conservation of this growth factor between lower and higher vertebrates.
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Affiliation(s)
- Iban Seiliez
- INRA, UMR1067 Nutrition Métabolisme et Aquaculture, Pôle d'hydrobiologie, CD918, F-64310 St-Pée-sur-Nivelle, France.
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28
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Hulmi JJ, Oliveira BM, Silvennoinen M, Hoogaars WMH, Ma H, Pierre P, Pasternack A, Kainulainen H, Ritvos O. Muscle protein synthesis, mTORC1/MAPK/Hippo signaling, and capillary density are altered by blocking of myostatin and activins. Am J Physiol Endocrinol Metab 2013; 304:E41-50. [PMID: 23115080 DOI: 10.1152/ajpendo.00389.2012] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Loss of muscle mass and function occurs in various diseases. Myostatin blocking can attenuate muscle loss, but downstream signaling is not well known. Therefore, to elucidate associated signaling pathways, we used the soluble activin receptor IIb (sActRIIB-Fc) to block myostatin and activins in mice. Within 2 wk, the treatment rapidly increased muscle size as expected but decreased capillary density per area. sActRIIB-Fc increased muscle protein synthesis 1-2 days after the treatment correlating with enhanced mTORC1 signaling (phosphorylated rpS6 and S6K1, r = 0.8). Concurrently, increased REDD1 and eIF2Bε protein contents and phosphorylation of 4E-BP1 and AMPK was observed. In contrast, proangiogenic MAPK signaling and VEGF-A protein decreased. Hippo signaling has been characterized recently as a regulator of organ size and an important regulator of myogenesis in vitro. The phosphorylation of YAP (Yes-associated protein), a readout of activated Hippo signaling, increased after short- and longer-term myostatin and activin blocking and in exercised muscle. Moreover, dystrophic mdx mice had elevated phosphorylated and especially total YAP protein content. These results show that the blocking of myostatin and activins induce rapid skeletal muscle growth. This is associated with increased protein synthesis and mTORC1 signaling but decreased capillary density and proangiogenic signaling. It is also shown for the first time that Hippo signaling is activated in skeletal muscle after myostatin blocking and exercise and also in dystrophic muscle. This suggests that Hippo signaling may have a role in skeletal muscle in various circumstances.
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Affiliation(s)
- Juha J Hulmi
- Department of Biology of Physical Activity, Neuromuscular Research Center, University of Jyväskylä, Jyväskylä, Finland.
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29
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Wall BT, Dirks ML, Verdijk LB, Snijders T, Hansen D, Vranckx P, Burd NA, Dendale P, van Loon LJC. Neuromuscular electrical stimulation increases muscle protein synthesis in elderly type 2 diabetic men. Am J Physiol Endocrinol Metab 2012; 303:E614-23. [PMID: 22739107 DOI: 10.1152/ajpendo.00138.2012] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Physical activity is required to attenuate the loss of skeletal muscle mass with aging. Short periods of muscle disuse, due to sickness or hospitalization, reduce muscle protein synthesis rates, resulting in rapid muscle loss. The present study investigates the capacity of neuromuscular electrical stimulation (NMES) to increase in vivo skeletal muscle protein synthesis rates in older type 2 diabetes patients. Six elderly type 2 diabetic men (70 ± 2 yr) were subjected to 60 min of one-legged NMES. Continuous infusions with L-[ring-¹³C₆]phenylalanine were applied, with blood and muscle samples being collected regularly to assess muscle protein synthesis rates in both the stimulated (STIM) and nonstimulated control (CON) leg during 4 h of recovery after NMES. Furthermore, mRNA expression of key genes implicated in the regulation of muscle mass were measured over time in the STIM and CON leg. Muscle protein synthesis rates were greater in the STIM compared with the CON leg during recovery from NMES (0.057 ± 0.008 vs. 0.045 ± 0.008%/h, respectively, P < 0.01). Skeletal muscle myostatin mRNA expression in the STIM leg tended to increase immediately following NMES compared with the CON leg (1.63- vs. 1.00-fold, respectively, P = 0.07) but strongly declined after 2 and 4 h of recovery in the STIM leg only. In conclusion, this is the first study to show that NMES directly stimulates skeletal muscle protein synthesis rates in vivo in humans. NMES likely represents an effective interventional strategy to attenuate muscle loss in elderly individuals during bed rest and/or in other disuse states.
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Affiliation(s)
- Benjamin T Wall
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, Maastricht, The Netherlands
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30
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Wang Q, McPherron AC. Myostatin inhibition induces muscle fibre hypertrophy prior to satellite cell activation. J Physiol 2012; 590:2151-65. [PMID: 22393251 DOI: 10.1113/jphysiol.2011.226001] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Muscle fibres are multinucleated post-mitotic cells that can change dramatically in size during adulthood. It has been debated whether muscle fibre hypertrophy requires activation and fusion of muscle stem cells, the satellite cells. Myostatin (MSTN) is a negative regulator of skeletal muscle growth during development and in the adult, and MSTN inhibition is therefore a potential therapy for muscle wasting diseases, some of which are associated with a depletion of satellite cells. Conflicting results have been obtained in previous analyses of the role of MSTN on satellite cell quiescence. Here, we inhibited MSTN in adult mice with a soluble activin receptor type IIB and analysed the incorporation of new nuclei using 5-bromo-2-deoxyuridine (BrdU) labelling by isolating individual myofibres. We found that satellite cells are activated by MSTN inhibition. By varying the dose and time course for MSTN inhibition, however, we found that myofibre hypertrophy precedes the incorporation of new nuclei, and that the overall number of new nuclei is relatively low compared to the number of total myonuclei. These results reconcile some of the previous work obtained by other methods. In contrast with previous reports, we also found that Mstn null mice do not have increased satellite cell numbers during adulthood and are not resistant to sarcopaenia. Our results support a previously proposed model of hypertrophy in which hypertrophy can precede satellite cell activation. Studies of the metabolic and functional effects of postnatal MSTN inhibition are needed to determine the consequences of increasing the cytoplasm/myonuclear ratio after MSTN inhibition.
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Affiliation(s)
- Qian Wang
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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31
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Kalista S, Schakman O, Gilson H, Lause P, Demeulder B, Bertrand L, Pende M, Thissen JP. The type 1 insulin-like growth factor receptor (IGF-IR) pathway is mandatory for the follistatin-induced skeletal muscle hypertrophy. Endocrinology 2012; 153:241-53. [PMID: 22087027 DOI: 10.1210/en.2011-1687] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Myostatin inhibition by follistatin (FS) offers a new approach for muscle mass enhancement. The aim of the present study was to characterize the mediators responsible for the FS hypertrophic action on skeletal muscle in male mice. Because IGF-I and IGF-II, two crucial skeletal muscle growth factors, are induced by myostatin inhibition, we assessed their role in FS action. First, we tested whether type 1 IGF receptor (IGF-IR) is required for FS-induced hypertrophy. By using mice expressing a dominant-negative IGF-IR in skeletal muscle, we showed that IGF-IR inhibition blunted by 63% fiber hypertrophy caused by FS. Second, we showed that FS caused the same degree of fiber hypertrophy in wild-type and IGF-II knockout mice. We then tested the role of the signaling molecules stimulated by IGF-IR, in particular the Akt/mammalian target of rapamycin (mTOR)/70-kDa ribosomal protein S6 kinase (S6K) pathway. We investigated whether Akt phosphorylation is required for the FS action. By cotransfecting a dominant-negative form of Akt together with FS, we showed that Akt inhibition reduced by 65% fiber hypertrophy caused by FS. Second, we evaluated the role of mTOR in FS action. Fiber hypertrophy induced by FS was reduced by 36% in rapamycin-treated mice. Finally, because the activity of S6K is increased by FS, we tested its role in FS action. FS caused the same degree of fiber hypertrophy in wild-type and S6K1/2 knockout mice. In conclusion, the IGF-IR/Akt/mTOR pathway plays a critical role in FS-induced muscle hypertrophy. In contrast, induction of IGF-II expression and S6K activity by FS are not required for the hypertrophic action of FS.
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Affiliation(s)
- S Kalista
- Pole of Endocrinology, Diabetes, and Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Avenue Hippocrate 55 bte B1.55.06, B-1200 Brussels, Belgium.
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