Department of Cell and Developmental Biology, Division of Metabolism, Endocrinology, and Diabetes, 109 Zina Pitcher Place, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA.
Mol Cell Biol. 2011 Jul;31(14):2787-801. doi: 10.1128/MCB.05437-11. Epub 2011 May 16.
The mammalian target of rapamycin complex 1 (mTORC1) functions as an environmental sensor to promote critical cellular processes such as protein synthesis, cell growth, and cell proliferation in response to growth factors and nutrients. While diverse stimuli regulate mTORC1 signaling, the direct molecular mechanisms by which mTORC1 senses and responds to these signals remain poorly defined. Here we investigated the role of mTOR phosphorylation in mTORC1 function. By employing mass spectrometry and phospho-specific antibodies, we demonstrated novel phosphorylation on S2159 and T2164 within the mTOR kinase domain. Mutational analysis of these phosphorylation sites indicates that dual S2159/T2164 phosphorylation cooperatively promotes mTORC1 signaling to S6K1 and 4EBP1. Mechanistically, S2159/T2164 phosphorylation modulates the mTOR-raptor and raptor-PRAS40 interactions and augments mTORC1-associated mTOR S2481 autophosphorylation. Moreover, mTOR S2159/T2164 phosphorylation promotes cell growth and cell cycle progression. We propose a model whereby mTOR kinase domain phosphorylation modulates the interaction of mTOR with regulatory partner proteins and augments intrinsic mTORC1 kinase activity to promote biochemical signaling, cell growth, and cell cycle progression.
哺乳动物雷帕霉素靶蛋白复合物 1（mTORC1）作为一种环境传感器，可响应生长因子和营养物质，促进蛋白质合成、细胞生长和细胞增殖等关键细胞过程。尽管有多种刺激物调节 mTORC1 信号通路，但 mTORC1 感知和响应这些信号的直接分子机制仍未得到明确界定。在这里，我们研究了 mTOR 磷酸化在 mTORC1 功能中的作用。通过使用质谱和磷酸特异性抗体，我们在 mTOR 激酶结构域内鉴定到 S2159 和 T2164 上新的磷酸化。对这些磷酸化位点的突变分析表明，双 S2159/T2164 磷酸化协同促进 mTORC1 信号转导至 S6K1 和 4EBP1。在机制上，S2159/T2164 磷酸化调节 mTOR-rapamycin 和 raptor-PRAS40 的相互作用，并增强 mTORC1 相关的 mTOR S2481 自身磷酸化。此外，mTOR S2159/T2164 磷酸化促进细胞生长和细胞周期进程。我们提出了一个模型，即 mTOR 激酶结构域磷酸化调节 mTOR 与调节蛋白的相互作用，并增强内在的 mTORC1 激酶活性，以促进生化信号转导、细胞生长和细胞周期进程。
