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: 6223922
• 负责人: JOSEPH AVRUCH
• 金额: $ 23.29万
• 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 2002-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6223922
• 关键词: active sites; binding proteins; biological signal transduction; cell cycle; cell growth regulation; enzyme mechanism; enzyme structure; genetic translation; intracellular transport; peptidylprolyl isomerase; phosphatidylinositol 3 kinase; phosphorylase kinase; phosphorylation; sirolimus; tissue /cell culture

Rapamycin is a potent immunosuppressive drug that halts cell cycle progression in the G1 phase in IL-2 activated T-cells, certain tumor cell lines and in yeast. The major cellular target of rapamycin, acting in situ as a complex with its binding protein (FKBP-12), is a novel 280 KDa polypeptide, first identified in yeast as TOR, and subsequently in mammalian cells. TOR is a kinase that phosphorylates phosphatidyl inositides and perhaps proteins, and is homologous in structure to the Ataxia-Teleangiectasia gene product. Yeast TOR is situated on the cytoplasmic surface of the vacuole. Rapamycin treatment of yeast delocalizes TOR from the vacuole, and elicits a phenotype equivalent to that seen with deletion of both TOR genes, and which resembles closely the response to nutrient deprivation; specifically, protein synthesis initiation is quickly and strongly inhibited, followed by G1 arrest. In mammalian cells, rapamycin, acting through mTOR, rapid inhibits both the phosphorylation of the 40 S ribosomal protein S6 (by inhibiting the p70 S6 kinase) and the phosphorylation and inactivation of eIF-4E-BP1, a negative regulator of the mRNA Cap binding protein, eIF-4E. Both these actions are accompanied by a selective inhibition in mRNA translation, which appears to underlie the inhibition of cell cycle progression. The studies proposed will uncover the physiologic and biochemical mechanisms by which mTOR participates in the regulation of mammalian cell growth by signalling to the translational apparatus. The cellular localization of mTOR will be defined, and the domains responsible for its localization mapped. The cellular binding site will be characterized. The regulation and properties of the mTOR-associated kinase catalytic activities will be defined. The cellular proteins that bind to mTOR will be isolated and examined for their role as effectors of mTORs signalling function. mTOR-regulated protein kinases or phosphatases active on eIF- 4E-BP1 will be sought, and the contribution of the p70 S6 kinase to the rapamycin-sensitive components of mTOR signalling will be established. These studies will define a new signal transduction pathway controlling cell growth in lymphoid and other cells.

雷帕霉素是一种有效的免疫抑制药物， IL-2激活的T细胞中G1期的进展，某些 肿瘤细胞 线和酵母中。 雷帕霉素的主要细胞靶点， 在 原位作为其结合蛋白（FKBP-12）的复合物，是一种新的 280 kDa 多肽，首先在酵母中被鉴定为TOR，随后在 哺乳动物细胞 TOR是一种使磷脂酰磷酸化的激酶 肌醇，也许还有蛋白质，并且在结构上与 的 共济失调-毛细血管扩张基因产物。 酵母TOR位于液泡的细胞质表面。 雷帕霉素处理酵母使TOR从液泡中迁移，并且 消除一种表型，其与同时缺失 Tor 基因，并密切类似的反应，营养 剥夺; 具体地，蛋白质合成起始快速且强烈地 抑制，然后是G1期阻滞。 在哺乳动物细胞中，雷帕霉素， 代理 通过mTOR，快速抑制40 S 核糖体蛋白S6（通过抑制p70 S6激酶）和 eIF-4 E-BP 1的磷酸化和失活，a阴性 调节器 mRNA帽结合蛋白eIF-4 E。 这两项行动都是 陪同 通过选择性抑制mRNA翻译，这似乎 的基础 抑制细胞周期进程。 这项研究将揭示人类的生理和生化特征， mTOR参与调控的机制 哺乳动物细胞 通过向翻译装置发送信号来生长。 蜂窝 mTOR的定位将被定义，负责的域 为其 定位映射。 细胞结合位点将是 表征了 mTOR相关激酶的调控及其特性 催化 活动将被定义。 细胞蛋白质结合到 mTOR将 分离并检查其作为mTOR效应物的作用 信令 功能 mTOR调节的蛋白激酶或磷酸酶活性， eIF- 4 E-BP 1的作用，以及p70 S6激酶对 的 mTOR信号传导的雷帕霉素敏感组分将被 确立了习 这些研究将定义一个新的信号转导途径 控制 淋巴细胞和其他细胞中的细胞生长。