Stem cell antigen-1 is necessary for cell-cycle withdrawal and myoblast differentiation in C2C12 cells
Stem cell antigen-1 is necessary for cell-cycle withdrawal and myoblast differentiation in C2C12 cells
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DOI：
10.1242/jcs.01548
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发表时间：
2004-12-01
影响因子：
4
通讯作者：
Bernstein, HS
中科院分区：
文献类型：
--
作者：
Epting, CL;López, JE;Bernstein, HS
调节成肌细胞分化和细胞周期退出的细胞外信号通路尚未完全了解。干细胞抗原-1（Sea-1/ Ly-6A/E）是一种糖基磷脂酰肌醇锚定的膜蛋白，已知其在T细胞活化中的作用，最近被描述为再生能力成肌细胞的标志物。我们以前确定，表达的Sca-1/1 Ly-6A是瞬时上调在肌细胞周期撤退，然而，一个特定的功能Sca-1在肌发生尚未被描述。在这里，我们表明，分化C2 C12成肌细胞的亚群的表面上的Sca-1的表达是最大的细胞周期撤退的时间，并阻止Sca-1与单克隆抗体或下调Sca-1表达的反义既促进增殖，抑制肌管形成。下调Sca-1表达在成肌细胞周期退出时解除Fyn的抑制，显性负性和组成性活性Fyn突变体分别拯救和重演Sca-1反义表型。这表明Fyn介导的Sca-1作用机制。因此，我们证明了Sca-1在C2 C12细胞早期肌发生中的前所未有的作用，并提出了一种新的途径，从成肌细胞表面到细胞内信号网络控制哺乳动物肌肉的增殖与分化。这些发现表明，除了作为肌肉祖细胞的标志物之外，Sca-1可能是促进肌肉再生的重要治疗靶点。
Extracellular signaling pathways regulating myoblast differentiation and cell-cycle withdrawal are not completely understood. Stem cell antigen-1 (Sea-1/ Ly-6A/E) is a glycosylphosphatidylinositol-anchored membrane protein known for its role in T-cell activation, and recently described as a marker for regeneration-competent myoblasts. We previously determined that expression of Sca-1/1Ly-6A is transiently upregulated during myocyte cell-cycle withdrawal; however, a specific function for Sca-1 in myogenesis has not been described. Here, we show that Sca-1 expression on the surface of a subpopulation of differentiating C2C12 myoblasts is maximal at the time of cell-cycle withdrawal, and that blocking Sca-1 with monoclonal antibodies or downregulating Sca-1 expression by antisense both promotes proliferation and inhibits myotube formation. Downregulating Sca-1 expression derepresses Fyn at the time of myoblast cell-cycle withdrawal, and dominant-negative and constitutively active Fyn mutants rescue and recapitulate the Sca-1 antisense phenotype, respectively. This suggests a Fyn-mediated mechanism for Sca-1 action. Thus, we demonstrate an unprecedented role for Sca-1 in early myogenesis in C2C12 cells, and propose a novel pathway from the myoblast cell surface to intracellular signaling networks controlling proliferation versus differentiation in mammalian muscle. These findings suggest that, beyond its role as a marker for muscle progenitors, Sca-1 may be an important therapeutic target for promoting muscle regeneration.