BAMBI acts as a molecular switch to determine the cell fate of C2C12 myoblasts

Myogenesis is a tightly regulated process by a cascade of well-coordinated events and pathways. In addition to the known myogenic regulatory factor (MRF) family, including Myf5, MyoD, myogenin, and MRF4, our previous study identified that BAMBI is involved in muscle regeneration and siRNA-mediated BAMBI knockdown impairs C2C12 myoblast differentiation. However, the potential role of BAMBI in determining cell lineage and fate specification in C2C12 myoblasts remains unexplored. In this study, we analyzed the RNA-seq data and discovered that BAMBI expression was dynamically regulated during the proliferation and differentiation period of C2C12 myoblasts. By establishing a cell line with the loss of function and gain of function of BAMBI in C2C12 myoblasts, we demonstrated that BAMBI deletion totally abrogated myogenic differentiation of C2C12 myoblast cells. In addition, loss of BAMBI converts C2C12 myoblasts to brown adipocytes through downregulation of MyoD and upregulation of Prdm16. Conversely, BAMBI overexpression strikingly enhanced myogenic differentiation of C2C12 myoblasts by upregulating MyoD expression. Taken together, our results establish that BAMBI is a vital myogenic factor involved in myoblast differentiation and a key regulator governing the balance between myogenic and adipogenic lineages in C2C12 myoblast cells.