mTOR Signaling Pathways

描述（由申请人提供）：mTOR是一种蛋白激酶，在参与控制细胞生长和增殖的途径中发出信号。胰岛素/生长因子和某些氨基酸均可刺激mTOR功能；然而，细胞中基本的激酶活性是如何被控制的还是一个谜。mTOR的不适当激活导致胰岛素抵抗，这是2型糖尿病发病的一个因素。mTOR抑制剂被用作免疫抑制剂，正在进行试验以评估其治疗癌症的疗效。显然，有必要更好地了解mTOR的控制和功能。最近发现了两个mTOR信号复合物。mTORC1含有mTOR、mLST8（与G蛋白β亚基同源）和raptor，后者结合被mTOR磷酸化的底物。雷帕霉素抑制mTORC1，它可能介导现在归因于mTOR的大部分功能。mTORC2不受雷帕霉素的抑制，mTORC2的下游靶点在很大程度上是未知的。mTORC2含有mTOR、mLST8和一种最初参与腺苷酸环化酶控制的蛋白pianissimo。我们通过酵母双杂交筛选和对与mTOR免疫沉淀的蛋白进行质谱分析，寻找新的mTOR相互作用蛋白。在研究涉及eIF3（一个关键的翻译起始因子）的相互作用时，我们发现胰岛素具有戏剧性的雷帕霉素敏感作用，可以刺激eIF3和eIF4G的关联。目的1是研究胰岛素的这种新的和潜在的重要作用。目的2是研究mTORC1和mTORC2的功能和控制。我们将测试胰岛素通过增加底物与猛禽的结合而增加mTORC1活性的假设。基于初步的研究结果，我们还提出验证胰岛素促进mTORC2形成的假设，以确定piissimo中的磷酸化位点，并研究mTORC2与cAMP产生之间的联系。目的3是确定mTORC1和mTORC2新的上游效应物和下游靶点。我们将研究ms鉴定出的新的候选mtor相互作用蛋白。最后，为了更好地了解mTORC2的机制，我们建议鉴定与piissimo相互作用的蛋白。

DESCRIPTION (provided by applicant): mTOR is a protein kinase that signals in pathways involved in the control of cell growth and proliferation. mTOR function is stimulated by both insulin/growth factors and certain amino acids; however, just how the essential kinase activity is controlled in cells is a mystery. Inappropriate activation of mTOR leads to insulin resistance, a contributing factor in the pathogenesis of type 2 diabetes. mTOR inhibitors are used as immunosuppressants, and trials are underway to evaluate their efficacy in treating cancer. Clearly, there is a need to understand better the control and function of mTOR. Two mTOR signaling complexes were recently discovered. mTORC1 contains mTOR, mLST8 (homologous to G protein beta subunits), and raptor, which binds substrates phosphorylated by mTOR. Rapamycin inhibits mTORC1, which probably mediates most of the functions now attributed to mTOR. mTORC2 is not inhibited by rapamycin, and the downstream targets of mTORC2 are largely unknown. mTORC2 contains mTOR, mLST8, and pianissimo, a protein originally implicated in the control of adenylate cyclase. We have searched for new mTOR interacting proteins by yeast two hybrid screening and by performing mass spectrometric (MS) analyses of proteins that immunoprecipitate with mTOR. In investigating an interaction involving eIF3, a key translation initiation factor, we discovered a dramatic rapamycin-sensitive action of insulin to stimulate the association of eIF3 and eIF4G. Aim 1 is to investigate this novel and potentially important effect of insulin. Aim 2 is to investigate the function and control of mTORC1 and mTORC2. We will test the hypothesis that insulin increases mTORC1 activity by increasing substrate binding to raptor. Based on preliminary findings, we also propose to test the hypothesis that insulin promotes formation of mTORC2, to identify the phosphorylation sites in pianissimo, and to investigate connections between mTORC2 and cAMP production. Aim 3 is to identify new upstream effectors and downstream targets of mTORC1 and mTORC2. We will investigate novel candidate mTOR-interacting proteins identified by MS. Finally, to understand better the mechanisms involved in mTORC2, we propose to identify pianissimo-interacting proteins.