Dataset for: NANDROLONE-INDUCED NUCLEAR ACCUMULATION OF MYOD PROTEIN IS MEDIATED BY NUMB, A NOTCH INHIBITOR, IN C2C12 MYOBLASTS

Signaling via the androgen receptor (AR) stimulates myogenic progenitor differentiation. In addition, myogenic differentiation factor D (MyoD) and Numb, a Notch inhibitor, play key roles in regulating myogenic differentiation. Nandrolone, an anabolic steroid, upregulates both MyoD and Numb expression in myogenic cells. However, the molecular mechanisms by which MyoD is upregulated by nandrolone are unclear. Moreover, the potential crosstalk between nandrolone, MyoD, and Numb is not well understood. With these considerations in mind, we examined the effects of nandrolone on the expression of MyoD mRNA and protein, and determined the interactions of MyoD and Numb in the presence or absence of nandrolone in differentiating C2C12 myoblasts. Nandrolone increased MyoD mRNA and protein expression and significantly enhanced nuclear translocation of MyoD protein. The later effect of nandrolone was blunted by siRNA against Numb. Immunoprecipitation studies confirmed that Numb forms complexes with MyoD. Chromatin immunoprecipitation revealed that in the presence of nandrolone, Numb is recruited to a region of the MyH7 promotor containing the E-box to which MyoD binds. These data indicate that nandrolone-regulated MyoD activation occurs mainly through a posttranslational mechanism which promotes MyoD nuclear accumulation, and suggest that this effect of nandrolone is, at least in part, mediated by Numb.

雄激素受体（androgen receptor, AR）介导的信号通路可刺激肌源性祖细胞分化。此外，肌分化因子D（Myogenic differentiation factor D, MyoD）以及Notch信号通路抑制剂Numb，在调控肌源性分化过程中发挥关键作用。同化类固醇类药物诺龙（nandrolone）可在肌源性细胞中上调MyoD与Numb的表达水平。然而，诺龙上调MyoD表达的具体分子机制仍不明确，且诺龙、MyoD与Numb三者间潜在的交叉调控关系也尚未得到充分阐释。基于上述研究背景与空白，本研究考察了诺龙对肌源性细胞中MyoD mRNA及蛋白表达的影响，并在处于分化阶段的C2C12成肌细胞模型中，检测了存在或不存在诺龙处理时MyoD与Numb的相互作用情况。实验结果显示，诺龙可提升MyoD的mRNA与蛋白表达水平，并显著增强MyoD蛋白的核转位效率。而靶向Numb的小干扰RNA（siRNA）可阻断诺龙的这一核转位促进效应。免疫沉淀（immunoprecipitation）实验证实，Numb可与MyoD形成蛋白复合物。染色质免疫沉淀（chromatin immunoprecipitation）实验结果表明，在诺龙存在的条件下，Numb会被招募至肌球蛋白重链7（MyH7）启动子中包含MyoD结合位点E盒的区域。上述实验数据表明，诺龙对MyoD激活的调控主要通过促进MyoD核积累的翻译后机制实现，且该调控效应至少部分由Numb介导。