Trenbolone enhances myogenic differentiation by enhancing beta-catenin signaling in muscle-derived stem cells of cattle

摘要

Testosterone is a key hormone regulating animal growth and development, which promotes skeletal muscle growth and inhibits fat deposition; however, the underlying mechanisms remain poorly defined. Because canonical Wingless and Int/beta-catenin signaling promotes myogenesis, we hypothesized that testosterone regulates myogenesis through enhancing the beta-catenin signaling pathway and the expression of its targeted genes. Muscle-derived stem cells were prepared from the skeletal muscle of fetal calf at day 180 of gestation and treated with or without trenbolone (10 nM), a synthetic analog of testosterone, in a myogenic medium. Trenbolone treatment increased the protein levels of MyoD and myosin heavy chain, as well as the androgen receptor content. The myogenic effect of trenbolone was blocked by cyproterone acetate, a specific inhibitor of androgen receptor, showing that the myogenic effect of trenbolone was mediated by the androgen receptor. Immunoprecipitation showed that androgen receptor and beta-catenin formed a complex, which was increased by trenbolone treatment. Trenbolone activated adenosine monophosphate activated protein kinase, which might phosphorylate beta-catenin at Ser552, stabilizing beta-catenin. Indeed, both cytoplasmic and nuclear beta-catenin levels were increased after trenbolone treatment. As a result, beta-catenin mediated transcriptional activity was enhanced by trenbolone treatment. In conclusion, these data provide evidence that testosterone increases cellular beta-catenin content which promotes the expression of beta-catenin targeted genes and myogenesis in the muscle-derived stem cells of cattle