Molecular basis of Cell Growth Control by the TOR kinase

TOR 激酶控制细胞生长的分子基础

• 批准号: 7742216
• 负责人: JOSEPH AVRUCH
• 金额: $ 43.75万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-04-01 至 2011-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7742216
• 关键词: Actins; Amino Acids; Antineoplastic Agents; Area; Award; Biochemical; Blood Vessels; Cell physiology; Cells; Clinical; Complex; Cytoskeleton; Development; Disease; Evaluation; Feedback; Growth Factor; Guanosine Triphosphate Phosphohydrolases; Human; Immunosuppressive Agents; Insulin; Insulin-Like Growth Factor I; Insulin-Like-Growth Factor I Receptor; Leucine; MAP Kinase Gene; Malignant Neoplasms; Methods; Molecular; Monomeric GTP-Binding Proteins; Multiprotein Complexes; Mutagenesis; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Pathway interactions; Phosphotransferases; Protein Kinase; Raptors; Regulation; Resistance; Signal Transduction; Sirolimus; Smooth Muscle Myocytes; Structure; TSC1/2 gene; Therapeutic Intervention; Tuberous Sclerosis; Withdrawal; Work; base; cell growth; cell growth regulation; human FRAP1 protein; in vivo; inhibitor/antagonist; insight; operation; overexpression; response

TOR, the "target of rapamycin" is a giant protein kinase that is critical to the regulation of cell growth in response to nutrient and energy sufficiency, to growth factors (such as insulin and IGF-1) and to other developmental signals. Rapamycin inhibits a subset of TOR's actions that underlie cell growth, and in some cell backgrounds, inhibits proliferation. Rapamycin is in clinical use because of its immunosuppressant action and antiproliferative effects on vascular smooth muscle cells; it is also under evaluation as an anti-cancer agent. Two sets of recent discoveries have provided important insight into TOR function and regulation, and work supported by this award has contributed to both areas. Biochemical methods established that TOR functions in two physically independent multiprotein complexes, only one of which (called TOR complex 1; TORC1) is inhibitable by Rapamycin. The interaction of TORC1 with its known substrates through raptor has been elucidated. TOR complex 2 is resistant to rapamycin, and appears to regulate the actin cytoskeleton through unknown effectors. TORC2 also serves as a necessary activating kinase (so called PDK2) for Akt, whereas TORC1 acts as a feedback inhibitor of Akt. Independently, the molecular connection between the insulin/IGF-1 receptors/Type 1 PI-3Kinase/Akt and TORC1 was shown to be the Tuberous Sclerosis heterodimer complex (TSC1/2) and Rheb, a Ras-like GTPase, Rheb is a positive regulator of mTOR signaling to TOR complex 1, that acts in part directly on TORC1. TSC1/2 is an activator of Rheb GTPase, thereby inhibiting Rheb; insulin/IGF-1, through Akt,and other inputs through the MAPK pathway suppress TSC GAP function, thereby promoting TORC1 signaling. Depletion of amino acids, especially leucine, inhibits TORC1 signaling, mostly independent of TSC1/2, but in a manner that is rescued by overexpressed Rheb. We find that leucine withdrawal disrupts'the interaction between Rheb and TOR. We propose to carry out a structure-function analysis of Rheb so as to understand how its interactions within TOR1 control TORC1 signaling, and define the biochemical mechanism by which leucine sufficiency controls the Rheb- mTOR interaction in vivo. We will characterize the transcriptional responses to Rheb-GTP, TORC1 and TORC2 and identify and characterize additional candidate Rheb effectors. In addition, we will elucidate the operation of TORC2, by defining the physical and functional interactions among the components unique to TORC2, the regulatory inputs that control TORC2 signaling in vivo, and the identity of additional TORC2 targets/substrates. The results of these studies will provide basis for therapeutic interventions in this pathway, which is crucial to both human cancers and to diseases like Type 2 diabetes

TOR，“雷帕霉素的靶点”是一种巨大的蛋白激酶，对于调节细胞生长的反应至关重要 营养和能量充足、生长因子（例如胰岛素和 IGF-1）以及其他发育 信号。雷帕霉素抑制细胞生长的 TOR 作用的子集，并且在某些细胞背景中， 抑制增殖。雷帕霉素因其免疫抑制作用和抗增殖作用而在临床使用 对血管平滑肌细胞的影响；它作为一种抗癌剂也正在接受评估。最近的两套 这些发现为 TOR 功能和监管以及该奖项支持的工作提供了重要的见解 对这两个领域都做出了贡献。生化方法证实 TOR 在两个物理上独立的功能中发挥作用 多蛋白复合物，其中只有一种（称为 TOR 复合物 1；TORC1）可被雷帕霉素抑制。这 TORC1 通过 raptor 与其已知底物的相互作用已被阐明。 TOR 复合物 2 具有抗性 雷帕霉素，似乎通过未知的效应器调节肌动蛋白细胞骨架。 TORC2 还充当 Akt 必需的激活激酶（所谓的 PDK2），而 TORC1 则充当 Akt 的反馈抑制剂。 独立地，胰岛素/IGF-1受体/1型PI-3激酶/Akt和TORC1之间的分子联系 被证明是结节性硬化症异二聚体复合物 (TSC1/2) 和 Rheb（一种 Ras 样 GTP 酶），Rheb 是一种 mTOR 信号转导至 TOR 复合物 1 的正调节因子，部分直接作用于 TORC1。 TSC1/2 是一个 Rheb GTPase 激活剂，从而抑制 Rheb；胰岛素/IGF-1，通过 Akt，以及其他输入 MAPK 通路抑制 TSC GAP 功能，从而促进 TORC1 信号传导。氨基酸耗尽， 尤其是亮氨酸，抑制 TORC1 信号传导，主要独立于 TSC1/2，但其方式可以通过 过度表达Rheb。我们发现亮氨酸戒断会破坏 Rheb 和 TOR 之间的相互作用。我们 建议对 Rheb 进行结构功能分析，以了解其在 TOR1 内的相互作用 控制 TORC1 信号传导，并定义亮氨酸充足性控制 Rheb- 的生化机制 mTOR 体内相互作用。我们将表征对 Rheb-GTP、TORC1 和 TORC2 的转录反应 并识别和表征其他候选 Rheb 效应器。此外，我们还将阐明以下操作： TORC2，通过定义TORC2特有的组件之间的物理和功能相互作用， 控制体内 TORC2 信号传导的调节输入，以及其他 TORC2 靶标/底物的身份。 这些研究的结果将为该途径的治疗干预提供基础，这对两者都至关重要 人类癌症和 2 型糖尿病等疾病