Regulation of myostatin expression and myoblast differentiation by FoxO and SMAD transcription factors
Regulation of myostatin expression and myoblast differentiation by FoxO and SMAD transcription factors
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DOI：
10.1152/ajpcell.00542.2005
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发表时间：
2007-01-01
影响因子：
5.5
通讯作者：
Unterman, Terry G.
中科院分区：
文献类型：
--
作者：
Allen, David L.;Unterman, Terry G.
肌生长抑制素是转化生长因子β（TGF β）家族的成员，在调节骨骼肌的生长和分化中起重要作用。在这里，我们研究了FoxO1和SMAD转录因子在调节肌生长抑制素基因表达和成肌细胞分化在体外C2C12肌管中的作用。在体内快收缩和慢收缩骨骼肌中，肌生长抑制素和FoxO1mRNA的表达均更高.此外，在分化的C2C12肌管中，FoxO1的组成型活性形式的表达增加了肌生长抑制素mRNA，并增加了肌生长抑制素启动子报告构建体的活性。高度保守的FoxO或SMAD结合位点的突变显著降低了肌生长抑制素启动子的活性，结合试验表明FoxO1和SMAD都结合到肌生长抑制素启动子中各自的位点。用TGF-β和/或SMAD 2、SMAD-3或SMAD-4的过表达处理也导致肌生长抑制素启动子活性的显著增加。用TGF-β沿着SMAD 2和FoxO 1的过表达处理导致肌生长抑制素启动子活性的最大增加。最后，TGF-β处理和SMAD2过表达大大增强FoxO1介导的成肌细胞分化抑制。这些数据共同表明，FoxO1和SMAD转录因子调节肌肉生长抑制素的表达，并有助于控制肌肉细胞的生长和分化。
Myostatin, a member of the transforming growth factor (TGF)-beta family, plays an important role in regulating skeletal muscle growth and differentiation. Here we examined the role of FoxO1 and SMAD transcription factors in regulating myostatin gene expression and myoblast differentiation in C2C12 myotubes in vitro. Both myostatin and FoxO1 mRNA expression were greater in fast- vs. slow- twitch skeletal muscles in vivo. Moreover, expression of a constitutively active form of FoxO1 increased myostatin mRNA and increased activity of a myostatin promoter reporter construct in differentiated C2C12 myotubes. Mutagenesis of highly conserved FoxO or SMAD binding sites significantly decreased myostatin promoter activity, and binding assays showed that both FoxO1 and SMADs bind to their respective sites in the myostatin promoter. Treatment with TGF-beta and/or overexpression of SMAD2, -3, or -4 also resulted in a significant increase in myostatin promoter activity. Treatment with TGF-beta along with overexpression of SMAD2 and FoxO1 resulted in the largest increase in myostatin promoter activity. Finally, TGF-beta treatment and SMAD2 overexpression greatly potentiated FoxO1-mediated suppression of myoblast differentiation. Together these data demonstrate that FoxO1 and SMAD transcription factors regulate the expression of myostatin and contribute to the control of muscle cell growth and differentiation.