Modulation of the mammalian target of rapamycin pathway by diacylglycerol kinase-produced phosphatidic acid
Modulation of the mammalian target of rapamycin pathway by diacylglycerol kinase-produced phosphatidic acid
复制标题
DOI：
10.1074/jbc.m412296200
复制
发表时间：
2005-03-18
影响因子：
4.8
通讯作者：
Mérida, I
中科院分区：
文献类型：
--
作者：
Avila-Flores, A;Santos, T;Mérida, I
被称为哺乳动物雷帕霉素靶蛋白（mTOR）的蛋白质通过整合不同的刺激物（如可用的营养素和促有丝分裂因子）来调节细胞生长。脂质信使磷脂酸（PA）结合并正向调节mTOR的促有丝分裂反应。因此，PA产生酶是mTOR的潜在调节剂。在这里，我们探讨了酶二酰甘油激酶（DGK），它产生PA通过磷酸化的二酰甘油这一途径的贡献。我们发现，在缺乏血清的HEK293细胞中，DGKzeta的过表达，而不是α亚型的过表达，诱导了mTOR依赖的p70S6激酶（p70S6K）磷酸化。加入血清后，p70S6K磷酸化水平更高，并且在过表达DGK zeta的细胞中对雷帕霉素处理更具抗性。这种DGK同种型对p70S6K过度磷酸化的作用需要mTOR PA结合区。在HEK293细胞中通过小干扰RNA下调内源性DGK zeta减少了血清诱导的p70S6K磷酸化，突出了这种亚型在mTOR通路中的作用。我们的研究结果证实了PA在mTOR调节中的作用，并描述了一种新的途径，其中DGK zeta衍生的PA作为mTOR信号传导的介质。
The protein known as mammalian target of rapamycin (mTOR) regulates cell growth by integrating different stimuli, such as available nutrients and mitogenic factors. The lipid messenger phosphatidic acid (PA) binds and positively regulates the mitogenic response of mTOR. PA generator enzymes are consequently potential regulators of mTOR. Here we explored the contribution to this pathway of the enzyme diacylglycerol kinase (DGK), which produces PA through phosphorylation of diacylglycerol. We found that overexpression of the DGK zeta, but not of the alpha isoform, in serum-deprived HEK293 cells induced mTOR-dependent phosphorylation of p70S6 kinase (p70S6K). After serum addition, p70S6K phosphorylation was higher and more resistant to rapamycin treatment in cells overexpressing DGK zeta. The effect of this DGK isoform on p70S6K hyperphosphorylation required the mTOR PA binding region. Down-regulation of endogenous DGK zeta by small interfering RNA in HEK293 cells diminished serum-induced p70S6K phosphorylation, highlighting the role of this isoform in the mTOR pathway. Our results confirm a role for PA in mTOR regulation and describe a novel pathway in which DGK zeta-derived PA acts as a mediator of mTOR signaling.