Myostatin inhibits myoblast differentiation by down-regulating MyoD expression
Myostatin inhibits myoblast differentiation by down-regulating MyoD expression
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DOI：
10.1074/jbc.m204291200
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发表时间：
2002-12-20
影响因子：
4.8
通讯作者：
Kambadur, R
中科院分区：
文献类型：
--
作者：
Langley, B;Thomas, M;Kambadur, R
肌生成抑制素是肌生成的负调节因子，通过控制成肌细胞的增殖发挥作用。在这项研究中，我们表明，肌肉生长抑制素是成肌细胞分化的抑制剂，这种抑制作用是通过Smad 3介导的。在体外，增加浓度的重组成熟肌肉生长抑制素可逆地阻断成肌细胞的成肌分化，在低血清培养基中培养。Western和北方印迹分析表明，在低血清培养基中加入肌生长抑制素抑制了MyoD、Myf 5、肌细胞生成素和p21的水平，导致肌细胞生成分化的抑制。用MyoD表达构建体瞬时转染C2 C12成肌细胞不能挽救肌生成抑制素抑制的肌源性分化。肌生成抑制素信号特异性地诱导Smad 3磷酸化并增加Smad 3-MyoD缔合，表明Smad 3可能通过干扰MyoD活性和表达来介导肌生成抑制素信号。与此一致，显性负性Smad 3的表达挽救了用肌生长抑制素处理的C2 C12成肌细胞中MyoD启动子-报告子的活性。总之，这些结果表明，肌生长抑制素抑制MyoD活性和表达通过Smad 3导致成肌细胞分化成肌管失败。因此，我们提出，肌生长抑制素在肌源性分化中起着关键作用，并且在缺乏功能性肌生长抑制素的动物中看到的肌肉增生和肥大是由于成肌细胞的增殖和分化失调。
Myostatin, a negative regulator of myogenesis, is shown to function by controlling the proliferation of myoblasts. In this study we show that myostatin is an inhibitor of myoblast differentiation and that this inhibition is mediated through Smad 3. In vitro, increasing concentrations of recombinant mature myostatin reversibly blocked the myogenic differentiation of myoblasts, cultured in low serum media. Western and Northern blot analysis indicated that addition of myostatin to the low serum culture media repressed the levels of MyoD, Myf5, myogenin, and p21 leading to the inhibition of myogenic differentiation. The transient transfection of C2C12 myoblasts with MyoD expressing constructs did not rescue myostatin-inhibited myogenic differentiation. Myostatin signaling specifically induced Smad 3 phosphorylation and increased Smad 3-MyoD association, suggesting that Smad 3 may mediate the myostatin signal by interfering with MyoD activity and expression. Consistent with this, the expression of dominant-negative Smad3 rescued the activity of a MyoD promoter-reporter in C2C12 myoblasts treated with myostatin. Taken together, these results suggest that myostatin inhibits MyoD activity and expression via Smad 3 resulting in the failure of the myoblasts to differentiate into myotubes. Thus we propose that myostatin plays a critical role in myogenic differentiation and that the muscular hyperplasia and hypertrophy seen in animals that lack functional myostatin is because of deregulated proliferation and differentiation of myoblasts.