title: Exercise training attenuates the hypermuscular phenotype and restores skeletal muscle function in the myostatin null mouse.
abstract: Myostatin regulates both muscle mass and muscle metabolism. The myostatin null (MSTN(-/-)) mouse has a hypermuscular phenotype owing to both hypertrophy and hyperplasia of the myofibres. The enlarged muscles display a reliance on glycolysis for energy production; however, enlarged muscles that develop in the absence of myostatin have compromised force-generating capacity. Recent evidence has suggested that endurance exercise training increases the oxidative properties of muscle. Here, we aimed to identify key changes in the muscle phenotype of MSTN(-/-) mice that can be induced by training. To this end, we subjected MSTN(-/-) mice to two different forms of training, namely voluntary wheel running and swimming, and compared the response at the morphological, myocellular and molecular levels. We found that both regimes normalized changes of myostatin deficiency and restored muscle function. We showed that both exercise training regimes increased muscle capillary density and the expression of Ucp3, Cpt1α, Pdk4 and Errγ, key markers for oxidative metabolism. Cross-sectional area of hypertrophic myofibres from MSTN(-/-) mice decreased towards wild-type values in response to exercise and, in this context, Bnip3, a key autophagy-related gene, was upregulated. This reduction in myofibre size caused an increase of the nuclear-to-cytoplasmic ratio towards wild-type values. Importantly, both training regimes increased muscle force in MSTN(-/-) mice. We conclude that impaired skeletal muscle function in myostatin-deficient mice can be improved through endurance exercise-mediated remodelling of muscle fibre size and metabolic profile.
authors: School of Biological Sciences, Hopkins Building, Whiteknights Campus, Reading, Berkshire RG6 6UB, UK. a.matsakas@gmail.com
authors: Antonios
authors: A
authors: Matsakas
authors: Raymond
authors: R
authors: Macharia
authors: Anthony
authors: A
authors: Otto
authors: Mohamed I
authors: MI
authors: Elashry
authors: Etienne
authors: E
authors: Mouisel
authors: Vanina
authors: V
authors: Romanello
authors: Roberta
authors: R
authors: Sartori
authors: Helge
authors: H
authors: Amthor
authors: Marco
authors: M
authors: Sandri
authors: Vihang
authors: V
authors: Narkar
authors: Ketan
authors: K
authors: Patel
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism / Q000502:physiology; D003593:Cytoplasm / Q000378:metabolism / Q000502:physiology; D017079:Exercise Tolerance; D006019:Glycolysis; D006984:Hypertrophy / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D055442:Metabolome; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000502:physiology*; D055435:Myostatin / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D009929:Organ Size; D010084:Oxidation-Reduction; D010641:Phenotype; D010805:Physical Conditioning, Animal; D013663:Teaching
chemical_list: D043925:Angiogenesis Inducing Agents; D055435:Myostatin