Sim2基因对PC12细胞周期的影响

观察Sim2基因对PC12细胞周期及细胞周期调控蛋白表达水平影响，初步阐明Sim2基因在Down综合征发病机制中的作用.以脂质体法将pcDNA3-mSim2真核表达载体瞬时转染PC12细胞；以RT-PCR方法检测mSim2基因在PC12细胞的表达；流式细胞仪观察细胞周期分布的变化；RT-PCR和免疫组织化学方法分别检测细胞周期调节蛋白Ｅ（cyclin E）和p27 mRNA和蛋白水平的表达变化.RT-PCR结果显示，瞬时转染pcDNA3-mSim2的PC12细胞中有明显的mSim2 mRNA表达；流式细胞仪检测发现，与对照组和空载体组相比，转染mSim2后，处于G₀/G₁期的PC12细胞百分比明显升高（Ｐ<0.01），而G₂/M期的细胞百分比明显降低 (Ｐ<0.01)；在mRNA和蛋白水平上，转染mSim2的细胞细胞周期蛋白E表达较对照组明显降低；而p27的表达明显升高(Ｐ<0.01).以上结果表明，mSim2基因可能通过影响神经元前体细胞的增殖在Down综合征发病机制中发挥了重要作用.

Effects of Mouse Sim2 Gene in Cell Cycle Regulation in PC12 Cells

To observe the effect of mSim2 on the cell cycle and to explore the role of Sim2 in the pathogenesis of Down syndrome,the pcDNA3-mSim2 plasmid was transiently transfected into PC12 with Lipofectamine~ TM . The expression of mSim2 in PC12 was detected by RT-PCR. The effect of mSim2 on the cell cycle was observed by flow cytometer. The mRNA and protein expression of cyclin E and p27 were detected by RT-PCR and immunohistochemistry respectively. There was an elevated expression of mSim2 in the cells transfected with pcDNA3-mSim2. Upon flow cytometry, there were more cells in G_0/G_1 phase and fewer cells in G_2/M phase in pcDNA3-mSim2-transfected cells. The mRNA and protein expression of cyclin E decreased in the mSim2-transfected cells, while p27 expression increased (P<0.01). The results indicated that mSim2 might play an important role in the pathogenesis of Down syndrome by inhibiting the cell cycle, which was related to the decreased cyclin E and increased p27 expression.