Caspases切割ARF-BP1调控p53信号通路的机制

项目名称： Caspases切割ARF-BP1调控p53信号通路的机制

项目编号： No.31471298

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 生物科学

项目作者： 张四清

作者单位： 厦门大学

项目金额： 85万元

中文摘要： ARF-BP1是抑癌基因p53的主要负调控者之一，通过泛素化修饰降解p53. 但对ARF-BP1的调控以及这些调控如何影响p53的功能却知之甚少，亟待深入研究。本申请项目发现ARF-BP1是一个新的重要caspase底物。caspase切割ARF-BP1可能调控p53的肿瘤抑制功能。前期工作中我们发现不同细胞凋亡刺激均导致caspase切割ARF-BP1，可能引起ARF-BP1降解，增强p53诱导的肿瘤细胞凋亡。我们还鉴定到一个caspase切割位点DYPD2473↓M. 未来将利用PCR点突变鉴定其它切割位点，及体外切割实验确定切割ARF-BP1的具体caspase. 并将切割位点突变的ARF-BP1转染细胞，研究其如何影响p53信号通路及改变肿瘤细胞凋亡。我们的发现不仅揭示了ARF-BP1及p53功能调控的一个重要机制，还将对设计新的肿瘤治疗方法和药物具有积极意义。后续研究争取新突破。

中文关键词： p53；细胞凋亡；caspase；ARF-BP1

英文摘要： The tumor suppressor p53 plays a key role in mediating DNA damage and oncogene activation induced tumor cell cycle arrest and/or apoptosis. ARF-BP1 is an E3 ligase of p53 and a major negative regulator of p53. ARF-BP1 mediated ubiquitination of p53 results in proteasomal degradation of p53, inhibiting the tumor suppressive function of p53. However, the mechanism that controls the activity of ARF-BP1 and how this affects the function of p53 are not well understood. In this study, we found ARF-BP1 is a substrate of caspases. Caspases control the activity of ARF-BP1. We found ARF-BP1 was cleaved in response to various apoptotic stimuli (including UV irradiation, TNFα﹢CHX stimulation, treatments with Taxol, Etoposide(VP16) and Cisplatin). Cleavage of ARF-BP1 occurred in several different tumor cell lines (Hela, Jurkat, MCF-7 etc.) undergoing apoptosis. The caspase inhibitor z-VAD-fmk prevented the cleavage of ARF-BP1, suggesting the cleavage was indeed mediated by caspases. After mutations of a couple of potential caspase cleavage sites, we identified a caspase cleavage site DYPD2473↓M in ARF-BP1. In future study, we will identify the other caspase cleavage sites in ARF-BP1, and characterize which caspase is responsible for the cleavage of ARF-BP1. Caspases-mediated cleavage might result in ARF-BP1 degradation, which will enhance p53 induced tumor cell death. We will investigate how caspase-mediated cleavage of ARF-BP1 regulates the tumor suppressive function of p53 and its relevance in tumorigenesis.

英文关键词： p53;apoptosis;caspase;ARF-BP1