Molecular Basis of p53-Induction to DNA Damage

描述（由申请人提供）：p53诱导DNA损伤的分子基础，p53激活的关键是取消MDM2靶向p53使其失活的能力。尽管有广泛的信息，但关于mdm2介导的p53降解及其调控的许多重要方面仍未完全了解，这在很大程度上归因于该过程的复杂性，该过程受多种信号通路的调节。我们前期研究发现p53的残基92-112是影响p53稳定性的重要序列。进一步的实验发现CRP2是与p53序列结合的蛋白质之一。值得注意的是，我们的初步研究提出了CRP2在p53稳定性调控中的作用，并得到了已发表报告的支持。我们实验室的其他工作发现MDM2的酸性结构域是除了无名指结构域之外的另一个区域，对于MDM2靶向p53进行全面泛素化至关重要。然而，酸性结构域如何促进mdm2介导的p53降解尚不清楚。最近的遗传学研究表明，MDM2和MDMX都是p53的重要负调节因子。然而，为什么MDM2和MDMX都不能弥补对方的损失尚不清楚。我们最近的研究表明，MDM2和MDMX之间的相互功能依赖表明，MDM2/MDMX异复合体可能是靶向p53降解的一个完整单元。通过选择p53-MDM2/MDMX模块作为研究的重点，我们建议将我们之前的研究扩展到三个具体目标，以阐明MDM2介导的p53降解和p53对应激反应的机制。

DESCRIPTION (provided by applicant): Molecular Basis of p53-induction to DNA Damage Essential to p53 activation is to abrogate the ability of MDM2 to target p53 for inactivation. Despite extensive information, many important aspects regarding MDM2-mediated p53 degradation and its regulation remain not fully understood, which is in large part attributable to the complexity of the process that is regulated by a wide array of signaling pathways. Our previous study identified the residues 92-112 of p53 as an important sequence affecting p53 stability. Further experiments uncovered CRP2 as one of the proteins bond to the p53 sequence. Significantly, a role for CRP2 in the regulation of p53 stability was suggested by our preliminary study and is also supported by published reports. Other work from our laboratory identified the acidic domain of MDM2 as another region, in addition to the ring finger domain, essential for MDM2 to target p53 for full ubiquitination. However, how the acidic domain contributes to MDM2-mediated p53 degradation remains unclear. Recent genetic studies have demonstrated both MDM2 and MDMX as essential negative regulators of p53 it is unknown, however, why neither mdm2 nor mdmx can compensate for the loss of the other. The mutual functional dependency between MDM2 and MDMX, as demonstrated by our recent studies, suggests that the MDM2/MDMX heterocomplex may function as an integral unit in targeting p53 for degradation. By choosing the p53-MDM2/MDMX module as the focal point of the investigation, we propose to extend our previous studies to three specific aims for elucidating the mechanisms underlying MDM2- mediated p53 degradation and the p53 response to stress. The specific aims are: 1. Assess CRP2, a protein that binds to the residues 92-112 of p53, for its role in Mdm2-targeted p53 ubiquitination/degradation and the p53 response to stress. 2. Investigate a role for the MDM2 acidic domain in p53 ubiquitination/degradation. 3. Functionally characterize the MDM2/MDMX heterocomplex in p53 regulation.