Degradation of the CDK inhibitor p27^<Kip1> by a novel ubiquitin ligase.

新型泛素连接酶降解 CDK 抑制剂 p27^<Kip1>。

基本信息

批准号：
17590243
负责人：
UCHIDA Chiharu
金额：
$ 2.24万
依托单位：
Hamamatsu University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17590243/
关键词：
p27kip1 Ubiquitin Proteasome Degradation Cell cycle p27<kip1>

项目摘要

Cell cycle progression is controlled by cyclin-dependent kinases (CDKs). The CDK activities are negatively regulated by CDK inhibitor proteins (CKIs). In the quiescent and early G1 phase, p27^<Kip1>, one of the Cip/Kip-type CKIs, exists in abundance in the cell nucleus to suppress cell cycle progression. p27^<Kip1> is degraded in late G1 phase by the ubiquitin-proteasome pathway, allowing cells to enter S phase. In this study, we identified p27NBP1 as a p27^<Kip1>-interacting protein. p27NBP1 physically interacted with p27^<Kip1> and directly ubiquitinated p27^<Kip1> in an intact RING finger domain-dependent manner. Since we isolated p27NBP1 as a protein that interacts with the amino-terminal portion of p27^<Kip1> containing Ser10, we next examined whether interaction between these two proteins was affected by Ser10 phosphorylation status. In spite of the substitution of Ser10, p27^<Kip1> mutants associated with p27NBP1 to an extent similar to that of wild-type p27^<Kip1>. This result suggested that p27NBP1 interacts with p27^<Kip1> regardless of the status of Ser10 phosphorylation. Ablation of endogenous p27NBP1 by small interfering RNA increased the steady-state level of p27^<Kip1> and decelerated p27^<Kip1> turnover. p27^<Kip1> was decreased in synchronization with accumulation of p27NBP1 in late G1 phase. Furthermore, depletion of p27NBP1 resulted in inhibition of cell cycle progression from G1 to S phase in a p53-independent manner. Overall, the results indicate that p27NBP1 acts as a negative regulator of p27^<Kip1> function by promoting ubiquitin-dependent proteasomal degradation.

细胞周期进程受细胞周期蛋白依赖性激酶（CDK）的控制。 CDK活性受CDK抑制剂蛋白（CKI）负调节。在静态和G1早期阶段中，CIP/KIP型CKI之一p27^<kip1>存在于细胞核中，以抑制细胞周期的进展。 p27^<kip1>通过泛素 - 蛋白酶体途径在G1后期降解，从而使细胞进入S相。在这项研究中，我们将P27NBP1鉴定为P27^<KIP1> - 互动蛋白。 p27nbp1与p27^<kip1>物理相互作用，并直接以完整的环形指域依赖性方式直接泛素化的p27^<kip1>。由于我们将P27NBP1分离为一种与含有Ser10的p27^<kip1>相互作用的蛋白质，因此我们接下来研究了这两种蛋白之间的相互作用是否受到Ser10磷酸化状态的影响。尽管取代了Ser10，但与p27NBP1相关的P27^<kip1>在与野生型P27^<kip1>相似的程度上。该结果表明，P27NBP1与p27^<kip1>相互作用，而不管Ser10磷酸化的状态如何。小干扰RNA消融内源性P27NBP1增加了p27^<kip1>的稳态水平，并减速了P27^<kip1>营业额。 p27^<kip1>在同步时与p27NBP1在G1后期的积累中降低。此外，P27NBP1的耗竭导致以p53独立的方式抑制细胞周期从G1到S相的进展。总体而言，结果表明，P27NBP1通过促进依赖泛素依赖性蛋白酶体降解来充当P27^<kip1>功能的负调节剂。