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.

雷帕霉素（MTOR）的哺乳动物靶标是一种蛋白激酶，该蛋白激酶对氨基酸和生长因子的响应控制多种细胞功能，部分是通过调节p70 S6激酶（p70S6K）的磷酸化和真核4e核纤维纤维4e结构蛋白1（4e-Bindind-Bindind-Bindind-Bindind-Binding protein 1（4e-bindine）1（4e-bindine-binting-binting prop1）。 MTOR调节体内P70S6K和4E-BP1的机制尚不完全了解。我们确定了一种新型的MTOR结合伴侣Raptor（MTOR的调节蛋白），该伴侣还结合了P70S6K和4E-BP1，对于体内信号传导至关重要。我们还证明了猛禽通过其各自的TOS（保守的TOR信号传导）基序与P70S6K和4E-BP1结合，这是一个先前证明是对这些MTOR依赖性调节所必需的短节段。 P70S6K或4E-BP1的TOS基序中的点突变已知废除氨基酸和MTOR调节，有选择地废除了它们与猛禽的结合。 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磷酸化的猛禽依赖性成分。 Raptor不会改变MTOR的内在催化活性，但似乎是一种MTOR支架蛋白，其与MTOR底物的TOS相结合对于有效的MTOR催化磷酸化是必不可少的，并且可能是为了赋予其对雷帕霉素和氨基酸的敏感性。