中文摘要：

　　目的探讨胚胎干细胞（ESC）向神经细胞（NC）定向诱导分化过程中跨膜信号分子Notch1蛋白的表达情况及意义。方法体外培养ESC,在培养基内添加5×10^-7mol/L维甲酸（RA）进行诱导分化。分别取ESC及RA诱导分化1、5、9d的细胞,倒置相差显微镜观察细胞形态变化,免疫细胞化学、Western Blot法及流式细胞术检测各相应时间点Notch1蛋白的表达。结果随诱导时间延长,ESC分化出的成熟神经元标志微管相关蛋白（MAP-2）阳性神经细胞逐渐增多,并形成较为单一密集的神经网络结构。ESC阶段Notch1蛋白为高水平表达,诱导分化后Notch1蛋白表达随时间延长逐渐下降。结论在ESC向NC的诱导分化过程中,Notch1信号逐渐关闭;Notch1可能对ESC向NC的特异性分化起重要作用。

英文摘要：

　[Objective]To investigate the protein expression of transmembrane signal transduction factor Notch1during inducing differentiation of embryonic stem cells（ESC） into neural cells.[Methods]ESC were cultured and committedly induced by 5×10^-7mol/L RA in vitro.Cells were taken from 4 time points：ESC,differentiated for 1d,5d and 9d.Morphologic changes were observed under inverted phase contrast microscope,MAP-2 antigen expressed in differentiated cells was detected by immunocytochemical method.Using immunocytochemistry,Western Blot,flow cytometry assay to investigate the Notch1 protein expression in esch time point.[Results]Along with the RA induction,MAP-2 positive neural cells increased and formed the neural network structure.ESC had the highest Notch1 protein level.Notch1 protein expression decreased gradually after induced differentiation.[Conclusion]During inducing ESC into neural cells,Notch1 signal closes gradually.Notch1 may play an important role in differentiating ESC to neural cells.