Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
J Cell Biol. 2011 Oct 31;195(3):435-47. doi: 10.1083/jcb.201107033. Epub 2011 Oct 24.
The rapamycin-sensitive mammalian target of rapamycin (mTOR) complex, mTORC1, regulates cell growth in response to mitogenic signals and amino acid availability. Phospholipase D (PLD) and its product, phosphatidic acid, have been established as mediators of mitogenic activation of mTORC1. In this study, we identify a novel role for PLD1 in an amino acid-sensing pathway. We find that amino acids activate PLD1 and that PLD1 is indispensable for amino acid activation of mTORC1. Activation of PLD1 by amino acids requires the class III phosphatidylinositol 3-kinase hVps34, which stimulates PLD1 activity through a functional interaction between phosphatidylinositol 3-phosphate and the Phox homology (PX) domain of PLD1. Furthermore, amino acids stimulate PLD1 translocation to the lysosomal region where mTORC1 activation occurs in an hVps34-dependent manner, and this translocation is necessary for mTORC1 activation. The PX domain is required for PLD1 translocation, mTORC1 activation, and cell size regulation. Finally, we show that the hVps34-PLD1 pathway acts independently of, and in parallel to, the Rag pathway in regulating amino acid activation of mTORC1.
雷帕霉素敏感的哺乳动物靶标（mTOR）复合物，mTORC1，可响应有丝分裂原信号和氨基酸可用性来调节细胞生长。已证实磷脂酶 D（PLD）及其产物磷脂酸是有丝分裂原激活 mTORC1 的介质。在这项研究中，我们确定了 PLD1 在氨基酸感应途径中的新作用。我们发现氨基酸可激活 PLD1，且 PLD1 对 mTORC1 的氨基酸激活是不可或缺的。氨基酸对 PLD1 的激活需要 III 类磷脂酰肌醇 3-激酶 hVps34，后者通过磷脂酰肌醇 3-磷酸与 PLD1 的 Phox 同源（PX）结构域之间的功能相互作用来刺激 PLD1 活性。此外，氨基酸刺激 PLD1 易位到溶酶体区域，mTORC1 在 hVps34 依赖性方式下在此处被激活，并且这种易位对于 mTORC1 的激活是必需的。PX 结构域对于 PLD1 易位、mTORC1 激活和细胞大小调节都是必需的。最后，我们表明 hVps34-PLD1 途径独立于 Rag 途径发挥作用，并且平行于 Rag 途径调节 mTORC1 的氨基酸激活。
