Function of a novel, sirtuin-regulated acetylation site on p53.

描述(申请人提供)：肿瘤抑制基因P53的激活是避免癌症发生的关键。这种激活在一定程度上是基于细胞内p53蛋白水平的增加。在响应遗传毒性侮辱时激活P53功能的另一个关键是增加对P53的特定翻译后修饰。在过去的15年里，人们致力于破译单个修饰如何控制P53的活性。我们最近发现了一种以前未知的修饰，赖氨酸残基357的乙酰化。这个残基位于p53的一个重要结构域--寡聚域附近。然而，目前尚不清楚K357乙酰化是否在P53功能的这一方面或其他方面发挥作用。此外，我们对负责添加和移除K357乙酰化的酶知之甚少。虽然我们的数据清楚地表明K357乙酰化在DNA损伤后迅速发生，但我们一直无法将K357乙酰化与经典的细胞周期停滞或p53的凋亡活性联系起来。相反，我们的初步研究表明，K357乙酰化在p53功能的另一个鲜为人知的方面发挥了作用，即诱导细胞衰老。此外，K357乙酰化似乎可能被白藜芦醇激活的sirtuin家族酶逆转。这些酶与衰老有关，提出了一个有吸引力的模型，即它们对K357乙酰化水平的控制可能有助于它们调节细胞衰老和衰老的能力。在这里，我们概述了一个实验计划，它将提供关于K357乙酰化的酶学及其功能后果的重要知识库。这些探索性研究包括体外生化分析和体内肿瘤抑制分析。总而言之，这些目标的成功完成应该会为我们提供关于我们定义的新的p53乙酰化事件的关键知识。这一知识库将允许进行更多的长期研究，最终可能在临床上利用这一途径。 公共卫生相关性：肿瘤抑制基因p53是人类癌症中最常见的突变基因，了解它如何帮助保护细胞免受恶性转化是癌症研究的中心目标。我们已经确定了一个新的调控事件，即P53关键结构域的乙酰化，它可能参与控制其功能。了解这种乙酰化事件的作用可能会导致对癌症的新诊断，并有可能在绝大多数肿瘤中存在P53途径损伤的患者中找到新的治疗策略。

DESCRIPTION (provided by applicant): Activation of the tumor suppressor p53 is critical for avoiding carcinogenesis. This activation is based partly on an increase in the cellular levels of p53 protein. Also critical for activating p53 function in response to genotoxic insults is the addition of specific post- translational modifications on p53. Over the past 15 years, a great deal of effort has been devoted to deciphering how individual modifications control p53 activity. We have recently identified a previously unknown modification, the acetylation of lysine residue 357. This residue lies adjacent to an essential structural domain of p53, the oligomerization domain. However, it remains unknown whether K357 acetylation plays a role in this or some other aspect of p53 function. Furthermore, we know little of the enzymes responsible for adding and removing K357 acetylation. While our data clearly demonstrate that K357 acetylation occurs rapidly after DNA damage, we have been unable to implicate K357 acetylation in the classical cell cycle arrest or apoptosis activities of p53. Instead, our preliminary studies suggest a role for K357 acetylation in a less well-understood aspect of p53 function, the induction of cellular senescence. Furthermore, it appears that K357 acetylation may be reversed by the resveratrol-activated sirtuin family of enzymes. These enzymes have been implicated in aging, presenting the attractive model that their control of K357 acetylation levels may contribute to their ability to regulate cellular senescence and aging. Here we outline an experimental plan that will provide an important knowledge base about the enzymology of K357 acetylation and about its functional consequences. These exploratory studies span in vitro biochemical analysis and in vivo tumor suppression assays. Cumulatively, the successful completion of these Aims should provide us with critical knowledge about the novel p53 acetylation event we have defined. This knowledge base will allow for more long-term studies that might ultimately exploit this pathway in the clinic. PUBLIC HEALTH RELEVANCE: The tumor suppressor p53 is the most commonly mutated gene in human cancer and understanding how it helps protect cells from malignant transformation is a central goal of cancer research. We have identified a new regulatory event, the acetylation of a critical domain of p53, that likely participates in controlling its function. Understanding the role of this acetylation event may lead to new diagnostics in cancer and potentially novel therapeutic strategies in the overwhelming percentage of patients whose tumors harbor lesions in the p53 pathway.