p38γ activity is required for maintenance of slow skeletal muscle size

Abstract

Introduction: p38γ kinase is highly enriched in skeletal muscle and is implicated in myotube formation. However, the activation status of p38γ in muscle is unclear. Methods: p38γ activity in slow and fast adult mouse skeletal muscle tissue was examined, as was the impact of p38γ deficiency on muscle development and gene expression. Results: p38γ is preferentially activated in slow muscle, but it is inactive in fast muscle types. Furthermore, the loss of p38γ in mice led to decreased muscle mass associated with a smaller myofiber diameter in slow muscle, but there was no impact on fast muscle in either mass or myofiber diameter. Finally, p38γ‐deficient muscle showed selective changes in genes related to muscle growth in slow muscle fibers. Conclusion: This study provides evidence that p38γ is selectively activated in slow skeletal muscle and is involved in the normal growth and development of a subset of skeletal muscle. Muscle Nerve, 2012