Lipogenesis in myoblasts and its regulation of CTRP6 by AdipoR1/Erk/PPARγ signaling pathway

The induced lipogenesis and its regulation in C2C12 myoblasts remain largely unclear. Here, we found that the cocktail method could significantly induce lipogenesis through regulating lipid metabolic genes and Erk1/2 phosphorylation in myoblasts. Meanwhile, the expression and secretion of CTRP6 were increased during ectopic lipogenesis. Moreover, CTRP6 knockdown downregulated the levels of lipogenic genes and phosphorylated Erk1/2 (p-Erk1/2) in the early lipogenic stage, whereas up-regulated p-Erk1/2 in the terminal differentiation. Interestingly, the effect of CTRP6 siRNA was attenuated by U0126 (a special p-Erk1/2 inhibitor) in myoblasts. Furthermore, AdipoR1, not AdipoR2, was first identified as a receptor of CTRP6 during the process of mitotic clonal expansion. Collectively, we suggest that CTRP6 mediates the ectopic lipogenesis through AdipoR1/Erk/PPAR gamma signaling pathway in myoblasts. Our findings will shed light on the novel biological function of CTRP6 during myoblast lipogenesis and provide a hopeful direction of improving meat quality of domestic animal by lipogenic regulation in skeletal muscle myoblasts.