Mechanistic Analysis of Papillimavirus E2 Functions

描述（由申请人提供）：乳头瘤病毒（PV）是一组小DNA病毒，可在多种高等脊椎动物（包括人类）中诱导良性病变。某些乳头瘤病毒，包括人乳头瘤病毒（HPV），如HPV 16和18，也与宫颈癌和其他人类肿瘤的发病机制有关。乳头瘤病毒建立持续性感染，其中病毒基因组在增殖宿主细胞的细胞核中以低拷贝数维持为自主复制质粒。在牛乳头瘤病毒（BPV 1）转化的小鼠细胞中，病毒基因组也复制为多拷贝核质粒，可以持续很长一段时间，以维持细胞的转化状态。为了确保在感染和转化细胞中的持久性，复制的病毒基因组必须在有丝分裂后在子细胞的细胞核中进行分配和维持。如果没有确保病毒基因组在核重组后定位在核膜内的机制，病毒基因组可能留在细胞质中，并在细胞分裂后通过降解或稀释而丢失。乳头瘤病毒E2蛋白是一种重要的调节蛋白，在病毒转录和病毒DNA复制中起关键作用，也是分裂细胞中病毒基因组维持所必需的。E2以及PV基因组与分裂细胞中的有丝分裂染色体密切相关。利用蛋白质组学方法系统地表征与体内E2相关的细胞蛋白，我们最近鉴定了Brd 4（含溴结构域蛋白4）作为E2相互作用蛋白，并表明它作为BPV 1 E2的有丝分裂染色体受体发挥作用。这项研究资助的重点是扩展对PV E2蛋白的研究，并研究E2与Brd 4相互作用对病毒生命周期其他方面的功能意义。破坏E2与Brd 4的结合可以阻断BPV 1对细胞的转化以及E2和病毒DNA与有丝分裂染色体的结合。将进行化学遗传筛选以鉴定E2/Brd 4结合的小分子抑制剂作为新型治疗性抗病毒化合物的潜在先导分子。

DESCRIPTION (provided by applicant): The papillomaviruses (PVs) are a group of small DNA viruses that induce benign lesions in variety of higher vertebrates, including humans. Certain papillomaviruses, including the human papillomaviruses (HPVs) such as HPV16 and 18, are also associated with the pathogenesis of cervical cancer and other human tumors. Papillomaviruses establish persistent infections in which the viral genomes are maintained as autonomous replicating plasmids at a low copy number in the nuclei of proliferating host cells. In bovine papillomavirus (BPV1) transformed mouse cells, the viral genomes also replicate as multicopy nuclear plasmids that can persist over long periods of time to maintain the transformation status of the cells. To ensure persistence in both infected and transformed cells, the replicated viral genomes must be partitioned and maintained in the nuclei of daughter cells following mitosis. Without a mechanism to ensure the localization of the viral genome within the nuclear envelope following nuclear reassembly, the viral genome could be left behind in the cytoplasm and lost either through degradation or dilution after cell division. The papillomavirus E2 protein, which is an important regulatory protein that plays critical roles in viral transcriptional and viral DNA replication, is also required for viral genome maintenance in dividing cells. E2, as well as the PV genomes, are closely associated with mitotic chromosomes in dividing cells. Utilizing a proteomic approach to systematically characterize cellular proteins that associate with E2 in vivo, we recently identified Brd4 (bromodomain-containing protein 4) as an E2 interacting protein and showed that it functions as the mitotic chromosome receptor for BPV1 E2. The focus of this research grant is to extend these studies on the PV E2 proteins and to examine the functional significance of the interaction of E2 with Brd4 to other aspects of the viral life cycle. Disruption of the binding of E2 to Brd4 can block the transformation of cells by BPV1 and the association of E2 and the viral DNA with mitotic chromosomes. Chemical genetic screens will be conducted to identify small molecule inhibitors of E2/Brd4 binding as potential lead molecules for novel therapeutic antiviral compounds.