Role of HPV16 E7/E2F6 interaction in viral oncogenesis

描述(申请人提供)：包括HPV16在内的高危人乳头瘤病毒(HPV)存在于几乎所有宫颈癌中。HPV的致癌作用是HPVE6和E7表达失调的结果。由于HPV基因组复制和病毒粒子产生发生在最分化的上皮细胞层，E6和E7颠覆了分化过程中发出生长停止信号的通路；例如，高危HPVE6和E7分别损害了P53和PRB肿瘤抑制因子。初步证据表明，HPV16E7癌蛋白可与细胞周期调控基因转录的特异性抑制因子E2F6相互作用。这项建议旨在通过免疫共沉淀、突变定位和报告分析来表征相互作用。E7对E2F6介导的抑制作用的变化将使用Northern和CHIP分析来确定。这一提议的中心假设是，E7解除了E2F6介导的转录抑制，从而提供了另一层控制，通过这一层控制，HPV确保受感染的宿主细胞保持S期的活性，这对病毒基因组复制至关重要，并可能有助于细胞转化。这些研究将进一步了解病毒蛋白如何与细胞因子相互作用而诱发癌症。

DESCRIPTION (provided by applicant): High-risk human papillomaviruses (HPVs), including HPV16, are present in nearly all cervical carcinomas. HPV-induced carcinogenesis is a result of the dysregulated expression of HPV E6 and E7. Because HPV genome replication and virion production occur in the most differentiated layers of the epithelium, E6 and E7 subvert pathways that signal growth arrest during differentiation; for instance, high-risk HPV E6 and E7 compromise the p53 and pRB tumor suppressors, respectively. Preliminary evidence shows that the HPV16 E7 oncoprotein can interact with E2F6, a specific repressor of transcription of cell cycle regulated genes. This proposal aims to characterize the interaction by co-immunoprecipitations, mutant mapping, and reporter assays. Changes in E2F6-mediated repression by E7 will be determined using Northern and ChIP analyses. The central hypothesis of this proposal is that E7 relieves E2F6-mediated transcriptional repression, thus providing yet another layer of control by which HPV ensures that the infected host cell remains S-phase competent, which is vital for viral genome replication and likely contributes to cellular transformation. These studies will further the understanding of how viral proteins interact with cellular factors to induce cancer.