A role for the Wnt3a/β-catenin signaling pathway in the myogenic program of C2C12 cells.

The Wnt/β-catenin signaling pathway is a key regulator of embryonic development that was first identified in drosophila. More recent work has suggested a role for this pathway in mammalian, myogenesis but this process remains to be more completely elucidated. The current study was designed to investigate the role of the Wnt3a/β-catenin signaling module in C2C12 cell differentiation and myotube formation. Activation of the Wnt/β-catenin pathway in differentiating myoblasts, using lithium chloride supplementation, increased both the number and size of C2C12 myotubes. On the other hand, pharmacological inhibitors of Wnt/β-catenin signaling (IWR-1, XAV939) resulted in significant decreases in myotube length without affecting their numbers. In separate experiments, a neutralizing antibody to Wnt3a also reduced myotube length without affecting the number of myotubes formed during differentiation. Confocal imaging studies revealed that β-catenin was primarily localized in the cytoplasmic region of undifferentiated myoblasts and differentiation resulted in its enhanced expression in myotubes. Additionally, LiCl treatment resulted in enhanced expression of β-catenin in pre-differentiating myoblast cultures. These data suggest that Wnt3a/β-catenin signaling plays a critical role in C2C12 cell differentiation and provides an appropriate model for elucidating its functions in more detail.