mTOR及其底物在HeLa细胞的细胞周期不同时相中的表达

为探讨细胞生长的机制 ,用RT PCR、Western印迹及蛋白激酶活性测定等方法对同步化的HeLa细胞的细胞周期不同时相中mTOR(mammaliantargetofrapamycin) ,p70S6激酶 (p70S6K)的α1 、α2 、β1 、β2 不同亚型及起始因子 4E结合蛋白 1 (4EBP1 )的表达进行了检测 .RT PCR的结果表明 :在G1 、S1 、G2 、M1 、M2 几个细胞周期时相中 ,mTOR的mRNA表达无明显变化 .mTOR的底物P70S6K的亚型α1 、α2 、β1 、β2 在M期表达均有明显增加 .4EBP1的表达在M期明显减少 .免疫印迹的结果与RT PCR的一致 ,即M期p70S6K的α1 、α2 、均有增加 ,4EBP1在M期减少 .活性测定表明 ,G2 期、M期mTOR较其它期有明显增加 ,4EBP1在M期活性有所下降 .研究结果表明 :mTOR、p70S6K、4EBP1很可能在HeLa细胞的生长中起重要的调节作用

Expression Of mTOR and Its Substrates in HeLa Cells in Different Cell Cycle Phases

In order to investigate the mechanism of cells growth, the expression of mTOR(mammalian target of rapamycin),and its α 1,α 2,β 1,β 2 isoforms of p70 S6 kinase(p70 S6K)and 4EBP1 in different cell cycle phases of synchronized HeLa cells were studied, by means of RT PCR, Western blot and protein kinase activity.The result of RT PCR showed that the expression of mTOR mRNA had not changed obviously. In M phase, the expression isoforms of α 1、α 2、β 1、β 2 of p70 S6K,the substrates of mTOR, increase obviously, while that of 4EBP1 decreases. The results of Immunoblots were same as the RT PCR. Activity assays showed that, in phase G 2 and M, the expression of mTOR maintains at higher level than any other phase, while 4EBP1 decreases in phase M. The result suggested that mTOR, p70 S6K and 4EBP1 might play important roles in regulation of HeLa cells growth.