AchR亚基基因启动子与分化/未分化肌细胞核因子的相互作用分析

Interaction Between Acetylcholine Receptor SubunitPromoter and Nuclear Factors in Differentiated andUndifferentiated Muscle Cells

采用凝胶阻滞实验比较分析了鸡烟碱样乙酰胆碱受体（ＡＣｈＲ）亚基基因－２７５／＋３６片段与分化／未分化肌细胞核抽提物的相互作用．发现未分化肌细胞核内存在两种直接识别ＡＣｈＲ启动子的结合活性，其结合反应不能被ＡＣｈＲα亚基基因增强子（含Ｅ盒子）竞争阻断，揭示此结合活性与ＭｙｏＤ家族无关，并表现为基因特异性结合；两种结合活性中一种结合活性既存在于未分化细胞，也存在于分化肌细胞，另一种结合活性只存在于未分化肌细胞．存在于未分化肌细胞、特异识别基因的结合活性不同于ＭｙｏＤ家族，也不同于已发现的Ｉｄ和Ｉ－ｍｆ（两者不能直接结合ＤＮＡ），可能与基因在未分化肌细胞中表达的负调控有关．

The interactions between chick acetylcholine receptor(AChR)subunit promoter extending from -275 to +36 and the nuclear extracts from differentiated and undifferentiated C2C12 muscle cells were analyzed by gel mobility shift assay.Several shift bands in gel mobility shift assay with the nuclear extracts from undifferentiated and differentiated C2C12 muscle cells were observed and two of which could not be abolished by α enhancer containing E boxes(CANNTG) indicating that the binding activities were not related to MyoD family and were specific for  promoter.One of the specific activities binding to  promoter resides in both of differentiated and undifferentiated cells,another only in undifferentiated cells.The specific binding activity of  promoter in undifferentiated cells,which is different from the activity of MyoD or Id and Imf,may be responsible for subunit gene supression in undifferentiated muscle cells.