Papillomavirus E2 Functions: Cellular Regulation and Effectors

描述(申请人提供)：人乳头瘤病毒(HPV)与许多人类癌症有因果关系。已经发现了100多种不同的HPV，其中许多与有发展为癌症风险的病变有关。根据其基因组序列的相关性，将乳头瘤病毒分为不同的属。一些阿尔法属HPV与宫颈癌、其他肛门生殖道癌以及大约20%的头颈癌有关。也有提示性的但尚未令人信服的证据表明，一些贝塔病毒属的HPV与一些非黑色素瘤皮肤癌有关。乳头瘤病毒E2基因产物在乳头瘤病毒中是保守的，是病毒转录、病毒复制和基因组维持的主要调节因子。E2蛋白在20世纪80年代首次被描述为一种转录因子，可以通过位于病毒基因组中的E2反应元件激活病毒转录。然而，E2还有其他功能，它既可以作为病毒转录的反式激活因子，也可以作为病毒转录的抑制因子，这取决于其结合位点在病毒基因组中的位置和背景。病毒DNA复制需要E2作为辅助DNA复制因子，帮助将病毒E1解旋酶招募到病毒DNA复制起点。此外，E2对于感染细胞的基因组维持是必不可少的，对于一些乳头瘤病毒来说，E2通过将病毒DNA与宿主细胞有丝分裂染色体结合和连接来发挥作用。2004年，我的实验室鉴定了溴域蛋白Brd4是一种主要的E2相互作用蛋白，并确定了它作为宿主有丝分裂染色体上BPVE2/DNA复合体的细胞系绳的功能。在过去的资金周期中，这笔赠款侧重于E2和Brd4，并确立了Brd4在调节各种E2功能方面的额外作用。这项拨款续期申请的重点是E2。第一个目标是认识到有更广泛的需要了解Brd4本身，并将进一步扩大我们对E2和Brd4功能的了解。第二个是这笔赠款的新领域，建议对20种不同类型的HPV E2蛋白相互作用进行广泛的无偏见分析。作为一种重要的多功能调节蛋白，E2在病毒生命周期的几个不同方面都是必需的，是HPV抗病毒药物开发的一个有吸引力的靶点。这些实验的最终目标是进一步深入了解调节和调节E2功能的细胞蛋白质和途径，期望其中一个或多个可能被利用来识别或开发小分子抑制剂。这些化合物将是进一步研究HPV-宿主细胞相互作用的有用工具，并可能成为模拟治疗乳头状瘤病毒感染的新型抗病毒药物的潜在线索。

DESCRIPTION (provided by applicant): The human papillomaviruses (HPVs) are causally linked to a number of human cancers. Over 100 different HPVs have been identified and many are associated with lesions that are at risk to progress to cancer. The papillomaviruses are divided into different genera based on the sequence relatedness of their genomes. Some of the alpha genus HPVs are associated with cervical cancer, other anogenital cancers, and approximately 20% of head and neck cancers. There is also suggestive but not yet compelling evidence implicating some of the beta genus HPVs in some non-melanoma skin cancers. The papillomavirus E2 gene product is conserved among papillomaviruses and functions as a major regulator of viral transcription, viral replication and genome maintenance. The E2 protein was first described in the 1980s to be a transcription factor that can activate viral transcription through E2 responsive elements located within the viral genome. E2 has additional functions however, and can serve either as a transactivator or a repressor of viral transcription depending upon the location and context of its binding sites within the viral genome. E2 is required for vira DNA replication as an auxiliary DNA replication factor that helps recruit the viral E1 helicase to the viral DNA replication origin. In addition, E2 is essential for genome maintenance in infected cells and, for some papillomaviruses, E2 functions by binding and linking the viral DNA to host cell mitotic chromosomes. In 2004 my laboratory identified the bromodomain protein Brd4 as a major E2 interacting protein and established its function as a cellular tether for the BPV E2/DNA complex on host mitotic chromosomes. In the past funding cycle, this grant focused on E2 and Brd4 and established additional roles for Brd4 in mediating various E2 functions. This grant renewal application focuses on E2. The first aim recognizes that there is a broader need for understanding Brd4 itself and will further extend our knowledge of E2 and Brd4 functions. The second is a new area for this grant, proposing a broad non-biased analysis of HPV E2 protein interactions across 20 different HPV types. As an important multifunctional regulatory protein required for several different aspects of the viral life cycle, E2 is an attractive target for the development of HPV antivirals. An ultimate goal of these experiments is to gain further insights into the cellular proteins and pathways that both regulate and mediate E2 functions, with the expectation that one or more of them might have the potential to be exploited for the identification or development of small molecule inhibitors. Such compounds would be useful tools for further studies of HPV-host cell interactions and could serve as potential leads for modeling novel antivirals to treat papillomavirus infections.