Studies on molecular mechanism of mTOR signaling that controls various cellular functions in response to amino acid sufficiency.

研究 mTOR 信号传导的分子机制，该信号传导响应氨基酸充足而控制各种细胞功能。

基本信息

批准号：
13680714
负责人：
YONEZAWA Kazuyoshi
金额：
$ 2.3万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

The mammalian target of rapamycin (mTOR) is a protein kinase that controls multiple cellular functions, including cell growth, in response to amino acids and growth factors, in part by regulating the phosphorylation of p70 S6 kinase (p70S6k) and eukaryotic initiation fector 4E-binding protein 1 (4E-BP1). The mechanisms by which mTOR regulates p70S6k and 4E-BP1 in vivo remain incompletely understood. We identified a novel mTOR-binding partner, raptor (regulatory associated protein of mTOR) that also binds p70S6k and 4E-BP1 and is essential for TOR signaling in vivo. We also demonstrated that raptor binds to p70S6k and 4E-BP1 through their respective TOS (conserved TOR signaling) motifs, a short conserved segment previously shown to be required for amino acid- and mTOR-dependent regulation of these mTOR substrates in vivo. A point mutation within the TOS motif of p70S6k or 4E-BP1 known to abolish both amino acid- and mTOR-regulation, selectively abolishes their binding to raptor. This mutation of the TOS motif also eliminates all in vitro mTOR-catalyzed 4E-BP1 phosphorylation and abolishes the raptor-dependent component of mTOR-catalyzed p70S6k phosphorylation in vitro. Raptor does not alter mTOR's intrinsic catalytic activity, but appears to serve as an mTOR scaffold protein whose binding to the TOS motif of mTOR substrates is necessary for effective mTOR-catalyzed phosphorylation in vivo and perhaps for conferring their sensitivity to rapamycin and amino acid sufficiency.

哺乳动物雷帕霉素靶蛋白 (mTOR) 是一种蛋白激酶，可响应氨基酸和生长因子控制多种细胞功能，包括细胞生长，部分通过调节 p70 S6 激酶 (p70S6k) 和真核起始因子 4E- 的磷酸化来实现。结合蛋白 1 (4E-BP1)。 mTOR 在体内调节 p70S6k 和 4E-BP1 的机制仍不完全清楚。我们鉴定了一种新的 mTOR 结合伴侣 raptor（mTOR 调节相关蛋白），它也结合 p70S6k 和 4E-BP1，并且对于体内 TOR 信号转导至关重要。我们还证明了 raptor 通过各自的 TOS（保守 TOR 信号传导）基序与 p70S6k 和 4E-BP1 结合，这是一个短的保守片段，之前表明是体内这些 mTOR 底物的氨基酸和 mTOR 依赖性调节所必需的。 p70S6k 或 4E-BP1 的 TOS 基序内的点突变已知会废除氨基酸和 mTOR 调节，选择性地废除它们与 raptor 的结合。 TOS 基序的这种突变还消除了所有体外 mTOR 催化的 4E-BP1 磷酸化，并消除了 mTOR 催化的 p70S6k 体外磷酸化的 raptor 依赖性成分。 Raptor 不会改变 mTOR 的内在催化活性，但似乎充当 mTOR 支架蛋白，其与 mTOR 底物的 TOS 基序的结合对于 mTOR 催化的体内有效磷酸化是必需的，并且可能赋予它们对雷帕霉素和氨基酸充足性的敏感性。