The myoblast is a precursor cell that rebuilds muscle tissue after trauma in human and animal skeletal muscle tissue. Proliferation of myoblasts is important for skeletal muscle damage repair and is controlled by numerous transcription factors and signals. The regulation of these signaling pathways and their complex interactions are not fully understood. This study aims to determine the physiological functions of Activin A, Notch and Sonic Hedgehog (Shh) signaling in the proliferation of mouse C2C12 myoblasts and to explore their interactions. Activin A facilitated proliferation of C2C12 cells and promoted the conversion of G1 into S phase in cell cycle, whereas addition of the receptor inhibitor SB431542 attenuated the proliferation activity of rActA on C2C12 cells. Activin A also activated Notch and Shh signaling, while blockage of these pathways attenuated the function of Activin A in cell cycle. Inhibition of the Notch signaling by Notch response inhibitor DAPT significantly down-regulated the expression of Shh signaling molecules, whereas exogenous rShh reversed the inhibition of C2C12 cells proliferative activity induced by DAPT, indicating Notch signaling act upstream of the Shh pathway. Furthermore, inhibition of Notch signaling weakened the activation of Activin A-mediated Shh signaling. Taken together, our results provide a novel role of Activin A in regulating the proliferation of C2C12 skeletal muscle cells, which impacts ActivinA-Notch1-Shh signaling pathways.

成肌细胞是在人和动物骨骼肌组织受到创伤后重建肌肉组织的前体细胞。成肌细胞的增殖对于骨骼肌损伤修复很重要，并受众多转录因子和信号的控制。这些信号通路的调节及其复杂的相互作用尚不完全清楚。这项研究旨在确定激活素A，Notch和Sonic Hedgehog（Shh）信号传导在小鼠C2C12成肌细胞增殖中的生理功能，并探讨它们之间的相互作用。激活素A促进C2C12细胞增殖，并在细胞周期中促进G1向S期的转化，而受体抑制剂SB431542的加入减弱了rActA在C2C12细胞上的增殖活性。激活素A也激活了Notch和Shh信号传导，这些通路的阻滞减弱了激活素A在细胞周期中的功能。Notch响应抑制剂DAPT对Notch信号的抑制显着下调了Shh信号分子的表达，而外源性rShh逆转了DAPT诱导的C2C12细胞增殖活性的抑制，表明Notch信号在Shh途径的上游起作用。此外，Notch信号的抑制减弱了激活素A介导的Shh信号的激活。两者合计，我们的结果提供了激活素A在调节C2C12骨骼肌细胞增殖中的新作用，这影响了ActivinA-Notch1-Shh信号通路。Notch响应抑制剂DAPT对Notch信号的抑制显着下调了Shh信号分子的表达，而外源性rShh逆转了DAPT诱导的C2C12细胞增殖活性的抑制，表明Notch信号在Shh途径的上游起作用。此外，Notch信号的抑制减弱了激活素A介导的Shh信号的激活。两者合计，我们的结果提供了激活素A在调节C2C12骨骼肌细胞增殖中的新作用，这影响了ActivinA-Notch1-Shh信号通路。Notch响应抑制剂DAPT对Notch信号的抑制显着下调了Shh信号分子的表达，而外源性rShh逆转了DAPT诱导的C2C12细胞增殖活性的抑制，表明Notch信号在Shh途径的上游起作用。此外，Notch信号的抑制减弱了激活素A介导的Shh信号的激活。两者合计，我们的结果提供了激活素A在调节C2C12骨骼肌细胞增殖中的新作用，这影响了ActivinA-Notch1-Shh信号通路。