Life Cycle of Human Papillomaviruses

描述（由申请人提供）：该基金的长期目标是研究调节人乳头瘤病毒（HPV）生产生命周期的机制，重点是E5，E1，E4和E6蛋白的作用。HPV感染基底上皮细胞并稳定维持游离体。当这些细胞分裂并经历分化时，诱导病毒基因组的生产性复制以及晚期基因表达的激活。为了了解调节病毒生命周期的途径，在完整病毒基因组的背景下进行了遗传分析。发现E5和E1^E4蛋白是完全激活分化依赖性晚期病毒功能所必需的。此外，还鉴定了E5的一系列潜在结合配偶体。在另外的研究中，我们确定了来自高风险和低风险HPV类型的E6蛋白对于未分化细胞中附加体的稳定维持是必需的。E6TP 1和含PDZ结构域的蛋白质的结合都显示出对于这种能力是重要的。进一步的研究表明，HPV基因产物在分化时激活半胱天冬酶，这是基因组扩增所必需的。E6蛋白激活抗凋亡蛋白，其可能起作用以阻断分化细胞中的过早凋亡。该更新申请集中于进一步研究E5、E1、E4和E6在分化依赖性生命周期中的作用。本人拟在本续期申请书中回答以下问题。 1)高危E5蛋白如何激活HPV生命周期的分化依赖性晚期？ 2)E1^E4蛋白在HPV生命周期的晚期提供了什么功能？他们的行动目标是什么？这些蛋白质与E5协同作用吗？ 3)E6如何促进未分化细胞中游离体的维持？E6在分化的细胞中控制哪些活动？

DESCRIPTION (provided by applicant): The long-term objective of this grant is to investigate the mechanisms that regulate the productive life cycle of human papillomaviruses (HPV) with a focus on the action of the E5, E1^E4 and E6 proteins. HPVs infect basal epithelial cells and stably maintain episomes. As these cells divide and undergo differentiation, the productive replication of viral genomes as well as activation of late gene expression is induced. In order to understand the pathways regulating the viral life cycle, a genetic analysis was performed in the context of complete viral genomes. The E5 and E1^E4 proteins were found to be necessary for full activation of differentiation-dependent late viral functions. In addition, a series of potential binding partners of E5 were identified. In additional studies we determined that the E6 proteins from both high and low risk HPV types are needed for the stable maintenance of episomes in undifferentiated cells. The binding of E6TP1 and PDZ- domain containing proteins were both shown to be important for this ability. Further studies demonstrated that HPV gene products activated caspases upon differentiation and this was necessary for genome amplification. The E6 protein activated anti-apoptotic proteins that likely act to block premature apoptosis in differentiating cells. This renewal application centers on further investigation of the roles of E5, E1^E4 and E6 in the differentiation dependent life cycle. I propose to address the following questions in this renewal application. 1) How do the high-risk E5 proteins activate the differentiation-dependent late phase of the HPV life cycle? 2) What functions do the E1^E4 proteins provide in the late phase of the HPV life cycle? What are their targets of action? Do these proteins function synergistically with E5? 3) How does E6 facilitate maintenance of episomes in undifferentiated cells? What activities does E6 control in differentiated cells?