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: 6416128
• 负责人: JOSEPH AVRUCH
• 金额: $ 31.16万
• 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/6416128
• 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，可以阻止细胞周期 IL-2 激活的 T 细胞在 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标，作用 在 原位与其结合蛋白（FKBP-12）形成复合物，是一种新型 280 千达拉 多肽，首先在酵母中被鉴定为 TOR，随后在 哺乳动物细胞。 TOR 是一种磷酸化磷脂酰的激酶 肌醇，可能还有蛋白质，并且在结构上同源 这 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。 酵母的雷帕霉素处理使 TOR 脱离液泡，并且 引发与删除两者相同的表型 托雷 基因，并且与对营养的反应非常相似 剥夺; 具体来说，蛋白质合成的启动是快速而强烈的 抑制，然后是 G1 停滞。 在哺乳动物细胞中，雷帕霉素， 表演 通过 mTOR，快速抑制 40 S 的磷酸化 核糖体蛋白 S6（通过抑制 p70 S6 激酶）和 eIF-4E-BP1 的磷酸化和失活，阴性 的调节器 mRNA Cap 结合蛋白，eIF-4E。 这两个动作都是 陪伴 通过选择性抑制 mRNA 翻译，这似乎 底层 细胞周期进程的抑制。 拟议的研究将揭示生理和生化 mTOR 参与调节的机制 哺乳动物细胞 通过向翻译装置发出信号来生长。 蜂窝式 mTOR 的本地化将被定义，并且负责的域 为其 定位已映射。 细胞结合位点将是 特点。 mTOR相关激酶的调控和特性 催化 将定义活动。 结合的细胞蛋白 mTOR 将 被分离并检查其作为 mTOR 效应器的作用 信令 功能。 mTOR 调节的蛋白激酶或磷酸酶活性于 eIF- 将寻找 4E-BP1，以及 p70 S6 激酶对 这 mTOR 信号传导的雷帕霉素敏感成分将 已确立的。 这些研究将定义新的信号转导途径 控制 淋巴细胞和其他细胞中的细胞生长。