Apoptosis Regulation by Adenovirus and Cellular Genes

描述（申请人提供）：在病毒感染的细胞中，细胞凋亡过程是一种细胞防御机制，限制病毒的复制和发病。人腺病毒（Ad）感染导致上皮细胞的生产性感染，而淋巴样细胞感染导致静态感染。对Ad感染上皮细胞的研究已经揭示了Ad凋亡程序的几个关键调控事件，但许多重要的检查点仍有待阐明。E1A癌基因的活性通过与细胞周期调节蛋白的相互作用来调节细胞周期，并促进病毒复制，也有助于感染细胞发生凋亡。E1B-19K蛋白是vBCL-2家族蛋白的一员，在抑制细胞凋亡中起主导作用。本研究将研究病毒基因如何调节上皮细胞模型中的核心细胞凋亡机制。目的1将确定哪些BH3-only Bcl-2家族效应蛋白在ad感染期间被激活，并确定其在病毒诱导的细胞凋亡中的作用。目的2将研究E1B-19K的抗凋亡活性与BH123家族蛋白BAK和BAX复合物形成之间的联系。该目的还将研究n端处理形式的BAX是否参与ad诱导的细胞凋亡的扩增。目的3将研究E1B-19K对p53细胞质靶向形式的直接凋亡活性的调节。目的4将探讨各种半胱天冬酶和凋亡内切酶在ad诱导的细胞凋亡中的作用。我们的研究将采用遗传和生化相结合的方法来确定ad诱导细胞凋亡的关键调控步骤。我们提出的研究将增加我们对病毒基因EIA和E1B-19K调节细胞Bcl-2家族基因活性的机制的理解，并确定干预病毒凋亡模式的潜在靶点。

DESCRIPTION (provided by applicant): In virus-infected cells, the process of apoptosis serves as a cellular defense mechanism to restrict viral replication and pathogenesis. Infection with human adenoviruses (Ad) results in productive infection of epithelial cells while infection of lymphoid cells results in quiescent infection. Studies on Ad-infected epithelial cells have revealed several key regulatory events of the Ad apoptosis program, but many important checkpoints remain to be illuminated. The activities of the E1A oncogene that modulate the cell cycle through interaction with cell cycle regulatory proteins and facilitate viral replication also contribute to the onset of apoptosis in infected cells. The E1B-19K protein, a member of the vBCL-2 family proteins plays a dominant role in suppression of apoptosis. This present renewal proposal will investigate how viral genes modulate the core cellular apoptotic machinery in epithelial cell models. Aim 1 will identify which of the BH3-only Bcl-2 family effector proteins is activated during Ad-infection and establish its role in virus-induced apoptosis. Aim 2 will investigate the link between the anti-apoptotic activity of E1B-19K and complex formation with BH123 family proteins BAK and BAX. This aim will also investigate if an N-terminally processed form of BAX is involved in amplification of Ad-induced apoptosis. Aim 3 will study modulation of a direct apoptotic activity of the cytoplasmically targeted form of p53 by E1B-19K. Aim 4 will investigate the role of various caspases and apoptotic endonucleases in Ad-induced apoptosis. Our studies would employ a combination of genetic and biochemical approaches to identify the critical regulatory steps in Ad-induced apoptosis. Our proposed studies will increase our understanding of the mechanism by which viral genes EIA and E1B-19K modulate the activities of cellular Bcl-2 family genes and identify potential targets for intervention in the viral apoptosis paradigm.