中文摘要：

目的探讨Id2在骨骼肌再生中的作用机制。方法用绿色荧光蛋白（GFP）-Id2-C2表达载体转染C2C12成肌细胞，对转染组和非转染组进行H2O2处理和2％马血清处理，用RT—PCR法观察两组细胞Id2基因表达的差异；Western blotting观察两组细胞的成肌分化相关蛋白的表达情况；免疫荧光显微镜观察正常组、纤维损伤组以及去神经支配组大鼠的骨骼肌中Id2和凋亡诱导因子（AIF）蛋白的表达情况。结果与非转染组相比，Id2转染组细胞成肌分化明显增强。免疫荧光染色法显示，50μmol／LH2O2能增加核Id2蛋白的表达。在氧化应激条件下，Id2能抑制成肌调节因子（MyoD）而活化肌浆蛋白（myogenin）。2％马血清能引起大多数Id2从细胞核迁移到细胞质，从而抑制活性氧（ROS）诱导的线粒体AIF表达。免疫荧光分析显示，去神经支配组大鼠的骨骼肌中细胞内的Id2和AIF蛋白表达增多。结论Id2从细胞核迁移到细胞质后能促进骨骼肌细胞分化，其作用与AIF表达水平相关。

英文摘要：

Objective To explore the functional role of Id2 in skeletal muscle regeneration. Methods Id2 expression vectors were transferred into C2C12 cells. The transferred and un-transferred C2C12 skeletal muscle cells were exposed to 50μmol/L H2O2 and 2% horse serum for 12 hours without fetal bovine serum（FBS）. Expression of Id2 gene in transferred and untransferred C2C12 cells was observed by RT-PCR. Expression of various myogenesis related proteins in the transferred and untransferred C2C12 cells were observed by Western blotting. Expression of Id2 and AIF proteins in the normal, fiber-damaged and denervated skeletal muscles were observed by immunofluoreseence. Results Compared with un-transferred cells, the Id2 transferred cells exhibited higher differentiation. Immunofluorescence staining revealed that 50μmol/L H202 treatment increased the expression of nucleic Id2. Under the oxidative stress, Id2 repressed both MyoD repressors and myogenin activator. Two percents of the horse serum, which usually was used to induce myoblasts differentiation, caused most of Id2 proteins transloeation from nucleus to cytoplasm. Translocation of Id2 protein from nucleus to cytoplasm inhibited the ROS-indueed expression of mitochondrial apoptosis inducing factor （AIF）. Immunofluorescence analysis implied that the denervated skeletal muscle showed more increased Id2 and AIF proteins in the nucleus. Conclusion Id2 translocation from nucleus to cytoplasm can accelerate differentiation of skeletal muscle cells. The functional role of Id2 during the skeletal muscle regeneration is related to the expression of AIF.