Role of Tip60 in Oncogene-Induced Senescence and Tumor Suppression

Tip60 在癌基因诱导的衰老和肿瘤抑制中的作用

• 批准号: 9214821
• 负责人: PEIQING SUN
• 金额: $ 18.32万
• 依托单位: WAKE FOREST UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9214821
• 关键词: Role; Tip60; Oncogene; Induced; Senescence

DESCRIPTION (provided by applicant): Senescence is a form of stable proliferative arrest historically associated with the exhaustion of replicative potential of cells. Activated oncogenes, such as ras, can induce senescence prematurely in young cells. Recent studies demonstrate that like apoptosis, oncogene-induced senescence is a bona fide tumor suppressing mechanism in vivo, which needs to be compromised during cancer development. However, the signaling pathways responsible for this important anti-tumorigenic response are poorly understood. Studies from our lab indicate that the p38 MAPK and its downstream substrate kinase PRAK play a key role in oncogenic ras-induced senescence and tumor suppression both in vitro and in vivo, and that PRAK is likely to be a tumor suppressor protein. Studies from the last funding period demonstrated that a multifunctional acetyltransferase Tip60 is also essential for oncogenic ras-induced senescence. Further analyses revealed a novel posttranslational modification cascade involving p38, Tip60 and PRAK, which plays an essential role in oncogenic ras-induced senescence. Upon activation by ras, p38 induces the acetyltransferase activity of Tip60 through phosphorylation of Thr158; activated Tip60, which directly interacts with PRAK, in turn induces the protein kinase activity of PRAK through acetylation of K364 in a manner that depends on phosphorylation of both Tip60 and PRAK by p38. These posttranslational modifications are critical for the pro-senescent function of Tip60 and PRAK, respectively. In the current renewal application, we propose to investigate the mechanism by which Tip60-mediated acetylation induces the activity and function of PRAK (Aims 1 and 2), and to determine the role of this novel posttranslational modification cascade in senescence induction and tumor suppression in a murine cancer model (Aim 3). In Aim 1, we will test a hypothesis that Tip60-mediated acetylation induces PRAK activity and function by enhancing p38 docking and/or by modulating its subcellular localization, 2 mechanisms that may not be mutually exclusive. In Aim 2, we will examine a possibility that Tip60-mediated acetylation disrupts the autoinhibitory conformation in the PRAK protein, leading to activation of PRAK, using biochemical and structural biology approaches. Finally in Aim 3, we will investigate the role of the p38-Tip60-PRAK cascade during senescence induction in vivo using the DMBA-induced skin carcinogenesis mouse model. These studies will likely reveal novel molecular mechanisms that regulate the activity and function of PRAK and other similar protein kinases, and provide new insights into signaling pathways mediating senescence and tumor suppression. Investigation of the p38-Tip60-PRAK cascade in vivo may lead to the development of novel cancer therapies targeting components of the senescence pathway.

描述（由申请人提供）：衰老是一种稳定的增殖停滞形式，历史上与细胞复制潜力的耗尽有关。激活的癌基因， 例如ras，可以诱导年轻细胞过早衰老。最近的研究表明，与细胞凋亡一样，癌基因诱导的衰老是体内真正的肿瘤抑制机制，但在癌症发展过程中需要对其进行损害。然而，人们对这种重要的抗肿瘤反应的信号通路知之甚少。我们实验室的研究表明，p38 MAPK 及其下游底物激酶 PRAK 在体外和体内致癌 ras 诱导的衰老和肿瘤抑制中发挥着关键作用，并且 PRAK 很可能是一种抑癌蛋白。上一个资助期的研究表明，多功能乙酰转移酶 Tip60 对于致癌 ras 诱导的衰老也至关重要。进一步的分析揭示了一种涉及 p38、Tip60 和 PRAK 的新型翻译后修饰级联，它在致癌 ras 诱导的衰老中发挥着重要作用。被 ras 激活后，p38 通过 Thr158 磷酸化诱导 Tip60 的乙酰转移酶活性；激活Tip60，它直接与 PRAK 反过来通过 K364 的乙酰化诱导 PRAK 的蛋白激酶活性，其方式取决于 p38 对 Tip60 和 PRAK 的磷酸化。这些翻译后修饰分别对于 Tip60 和 PRAK 的促衰老功能至关重要。在当前的更新申请中，我们建议研究Tip60介导的乙酰化诱导PRAK活性和功能的机制（目标1和2），并确定这种新型翻译后修饰级联在衰老诱导和肿瘤抑制中的作用。小鼠癌症模型（目标 3）。在目标 1 中，我们将测试一个假设，即 Tip60 介导的乙酰化通过增强 p38 对接和/或调节其亚细胞定位（这两种机制可能并不相互排斥）来诱导 PRAK 活性和功能。在目标 2 中，我们将使用生化和结构生物学方法研究 Tip60 介导的乙酰化破坏 PRAK 蛋白中的自抑制构象，从而导致 PRAK 激活的可能性。最后，在目标 3 中，我们将使用 DMBA 诱导的皮肤癌小鼠模型研究 p38-Tip60-PRAK 级联在体内衰老诱导过程中的作用。这些研究可能会揭示调节 PRAK 和其他类似蛋白激酶的活性和功能的新分子机制，并为介导衰老和肿瘤抑制的信号通路提供新的见解。对体内 p38-Tip60-PRAK 级联的研究可能会导致针对衰老途径成分的新型癌症疗法的开发。