Cellular Targets of Polyomavirus Transforming Proteins

描述(由申请者提供)：对细胞蛋白质的研究 以乳头状病毒的肿瘤抗原为靶点的研究证明越来越多 对我们理解人类癌症很重要，产生了重要的见解 转化为在癌症中起作用的信号转导途径。我们有 多瘤病毒中(MT)和小(ST)肿瘤靶点的确定 抗原，如蛋白磷酸酶2A(PP2A)，一种高度保守的酶，已知 参与细胞增殖和凋亡的调控。这种酶是 对多瘤病毒诱导的肿瘤形成很重要，也一直是 与人类癌症有关，既是突变或调控不当的目标，也是 作为抗癌治疗的潜在靶点。中国的长期目标是 提议的项目是帮助描绘调控的分子机制 PP2A，特别是在细胞周期、细胞凋亡和癌症中。这项研究将引领 到识别新的细胞药物靶点，这将使我们能够 特异性地调节PP2A在细胞凋亡和癌症相关途径中的功能。 在这些靶点水平发挥作用的药物可能毒性较低， 因此对抗癌治疗更有用。因此，这笔赠款将集中于 1)了解MT和ST信号如何阻断细胞凋亡；2)了解 MT和ST如何改变PP2A的功能，3)确定PP2A的作用机制 针对特定底物，以及4)阐明PP2A的正常机制 监管。在Aim I中，我们将使用wt和突变体STS和MTS以及 用环氧合酶-2抑制剂判断MT和ST是否对PI有调节作用 PP2A结合和/或3-K/Akt/Bad/Bc l-2抗细胞凋亡通路 环氧合酶-2诱导。我们还将调查Akt和Bcl-2是否 利用免疫共沉淀法靶向已知的PP2A调节亚基 接近了。在AIM II中，我们将测试哪些PP2A调节亚基是 在体内，MT和ST的表达取代了PP2A。此外，我们还将 研究一个新家族的正常和MT/ST调节的磷酸化 PP2A靶向亚基。最后，在AIM III中，我们将探讨这种机制 在甲基转移酶水平上调节PP2A甲基化 通过测试这些酶是否受 区域化或磷酸化。

DESCRIPTION (provided by applicant): The study of cellular proteins that are targeted by the tumor antigens of papovaviruses is proving increasingly important to our understanding of human cancer, yielding important insights into signal transduction pathways that play a role in cancer. We have identified one of the targets of polyomavirus middle (MT) and small (ST) tumor antigens as protein phosphatase 2A (PP2A), a highly conserved enzyme known to be involved in the control of cell proliferation and apoptosis. This enzyme is important for polyomavirus-induced tumorigenesis and has also has been implicated in human cancer, both as a target of mutation or misregulation and as a potential target for anti-cancer therapies. A long-term goal of the proposed project is to help delineate the molecular mechanisms that regulate PP2A, especially in cell cycle, apoptosis, and cancer. This research will lead to the identification of new cellular drug targets that will allow us to more specifically modulate PP2A function in apoptosis- and cancer-relevant pathways. Drugs that function at the level of these targets would likely be less toxic, and therefore more useful for anti-cancer therapy. Thus, this grant will focus on 1) understanding how MT and ST signal to block apoptosis, 2) understanding how MT and ST alter PP2A function, 3) identifying mechanisms by which PP2A is targeted to specific substrates, and 4) elucidating normal mechanisms of PP2A regulation. In Aim I, we will use wt and mutant STs and MTs and cyclooxygenase-2 inhibitors to determine if MT and ST modulate the PI 3-kinase/Akt/Bad/Bcl-2 anti-apoptotic pathway by PP2A binding and/or cyclooxygenase-2 induction. We will also investigate whether Akt and Bcl-2 are targeted by known PP2A regulatory subunits by using coimmunoprecipitation approaches. In Aim II, we will test which PP2A regulatory subunits are displaced from PP2A in vivo by expression of MT and ST. Moreover, we will investigate normal and MT/ST modulated phosphorylation of a novel family of PP2A targeting subunits. Finally, in Aim III we will investigate the mechanism of regulation of PP2A methylation at the level of the methyltransferase and methylesterase enzymes by testing whether these enzymes are regulated by compartmentalization or phosphorylation.