Knockdown of CSRP3 inhibits differentiation of chicken satellite cells by promoting TGF-β/Smad3 signaling.

Muscle LIM protein (MLP/CSRP3/CRP3) is a microtubule-associated protein preferentially expressed in cardiac and skeletal muscle and has a central role during muscle development and for architectural maintenance of muscle cells. LIM-domain proteins act as both modulators and downstream targets of TGF-β signaling, which is well documented to negatively regulate differentiation of myogenic precursor cells or myoblasts. Herein, we determined whether CSRP3 regulates chicken satellite cell proliferation and differentiation in vitro, and examined its mechanism of action by focusing on the TGF-β signaling pathway. Interference of CSRP3 mRNA expression had no effect on the proliferation of satellite cells, but significantly inhibited satellite cell differentiation into myotubes at 24, 48, and 72 h after initiation of differentiation. However, CSRP3 overexpression did not affect the proliferation or differentiation of satellite cells. Moreover, knockdown of CSRP3 caused up-regulation of TGF-β and Smad3 mRNA and protein levels. The phosphorylation of Smad3 in CSRP3-knockdown cells was greater than that in wild-type cells at 24, 48, and 72 h after initiation of differentiation. Collectively, knockdown of CSRP3 suppressed chicken satellite cell differentiation by regulating Smad3 phosphorylation in the TGF-β signaling pathway. Our results indicate that CSRP3 might play an important role in promoting satellite cell differentiation in chicken.