RESUMO
INTRODUCTION: Transforming growth factor-beta (TGF-ß) is a well-known regulator of fibrosis and inflammation in many tissues. During embryonic development, TGF-ß signaling induces expression of the transcription factor scleraxis, which promotes fibroblast proliferation and collagen synthesis in tendons. In skeletal muscle, TGF-ß has been shown to induce atrophy and fibrosis, but the effect of TGF-ß on muscle contractility and the expression of scleraxis and atrogin-1, an important regulator of muscle atrophy, were not known. METHODS: We treated muscles from mice with TGF-ß and measured force production, scleraxis, procollagen Iα2, and atrogin-1 protein levels. RESULTS: TGF-ß decreased muscle fiber size and dramatically reduced maximum isometric force production. TGF-ß also induced scleraxis expression in muscle fibroblasts, and increased procollagen Iα2 and atrogin-1 levels in muscles. CONCLUSION: These results provide new insight into the effect of TGF-ß on muscle contractility and the molecular mechanisms behind TGF-ß-mediated muscle atrophy and fibrosis.
