ERK在NGF诱导PC12 细胞分化中的作用

目的探讨细胞外信号调节激酶(ERK)在NGF。诱导的PC12细胞分化中的作用机制。方法以NGF处理PC12细胞建立分化模型，运用免疫印迹检测不同浓度不同作用时间时NGF对ERK1／2蛋白和磷酸化ERK1／2蛋白水平的影响，并观察MAPK／ERK激酶(MEK)抑制剂U0126对NGF诱导的细胞形态学改变的影响。结果ERK1／2蛋白的磷酸化呈现NGF剂量和时间依赖性。NGF作用细胞5min即可观察到明显的ERK1／2蛋白磷酸化，持续1h左右，2h时降低到初始水平，而细胞形态的改变出现在NCF作用12h以后。倒置相差显微镜观察可见PC12细胞分化的程度与ERK1／2活化持续的时间正相关，U0126可完全即时抑制ERK1／2的活化，而ERK1／2活化的抑制可完全阻断。NGF诱导的PC12细胞分化。结论ERK1／2的活化是PC12细胞发生分化的必需事件，其活化时间的长短对分化具有决定作用。

Role of ERK in PC12 cells Induced by differentiation NGF

Objective To decide whether the extracellular signal-regulated kinase (ERK) play a crucial role in PC12 differentiation induced by nerve-growth factor (NGF). Methods Cells were treated with NGF, and cell extracts were subjected to immunobblotting with antibodies against ERK1/2 and pp-ERK1/2. To more clearly define the role of ERK1/2, a small molecule inhibitor of MAPK/ERK kinase named U0126 was examined for its effect on the cellular action of NGF in PC12 cells. Results We showed that NGF induced sustained activation of ERK1/2 in 1 h. In the presence of U0126, however, NGF-induced differentiation were no longer observed and the expression of pp-ERK1/2 was severely impaired. Conclusion Our results indicated that sustained activation of ERK1/2 in the early stage of cell differentiation is necessary for NGF-induced neurite outgrowth, and the differentiation was markedly regulated by NGF treatment through activation of the ERK1/2 pathway. In a word, activation of ERK1/2 is essential to neuronal differentiation of PC12 cells.