The essential role of gamma-secretase in human papillomavirus infection

描述（由申请人提供）：人乳头瘤病毒（hpv）由二十面体衣壳内相对较小的圆形双链DNA基因组组成。在迄今已确定的100多个HPV毒株中，约有40个基因型与生殖器疾病有关。HPV感染通常是无症状的，不会引起疾病。然而，如果病毒基因组保持在低水平的潜伏期，并逃避免疫识别，HPV可能导致异常细胞变化和严重疾病。根据其致癌潜力和与癌症发展的关系，感染生殖道的人乳头状瘤病毒可分为两组。低风险的hpv引起生殖器疣，很少与肿瘤发生有关。然而，一些高危hpv（如HPV16）已被公认为宫颈癌的致病因子和其他几种上皮癌类型的辅助因子。目前，这两种HPV疫苗只能针对有限的致癌HPV，并且不是所有国家都负担得起。在HPV进入过程中，硫酸肝素蛋白聚糖（HSPGs）作为附着因子增加HPV感染的效率。与HSPGs结合导致病毒颗粒的构象改变和衣壳蛋白L2的裂解，随后病毒粒子与一个未识别的次级进入受体相互作用。HPV颗粒主要通过胞吞作用进入细胞，以菌株和细胞类型依赖的方式进入细胞，病毒颗粒的分解发生在低ph的核内体中。细胞骨架被认为参与了HPV细胞内运输。对HPV进入和贩运机制的不了解限制了新疫苗和抗病毒药物的开发。全基因组siRNA筛选发现γ -分泌酶（J-sec）是上皮细胞感染HPV16的一个重要因素，尽管其机制尚未得到很好的表征。本课题将研究J-sec及其底物在HPV16感染人上皮细胞过程中的功能。本研究的第一个目的是利用新开发的技术专门测量病毒的分解和病毒颗粒的定位，研究HPV16感染过程中需要J-sec的关键步骤。这些步骤被J-sec活性的丧失所抑制

DESCRIPTION (provided by applicant): Human papillomaviruses (HPVs) are composed of relatively small circular, double-stranded DNA genomes within icosahedral capsids. Among the over 100 HPV strains identified so far, approximately 40 genotypes are associated with genital diseases. HPV infection is generally asymptomatic and doesn't cause disease. However, if the virus genome is maintained at a low level termed latency and evades immune recognition, HPV may lead to abnormal cell changes and severe diseases. The HPVs that infect genital tract could be divided into two groups, based on their oncogenic potential and association with cancer development. The low-risk HPVs cause genital warts, and seldom linked to tumorigenesis. However, some high-risk HPVs (such as HPV16) have been well recognized as the causative agents of cervical cancer and as cofactors for several other epithelial cancer types. Currently, the two HPV vaccines can only target limited oncogenic HPVs and are not affordable in all the countries. During HPV entry, heparan sulfate proteoglycans (HSPGs) serve as the attachment factor to increase efficiency of HPV infection. Binding to HSPGs leads to the conformational change in the viral particles and cleavage of capsid protein L2, followed by the interaction of virion with a secondary unidentified entry receptor. HPV particles enter cells mainly through endocytosis in a strain and cell type dependent manner, and disassembly of virus particle occurs in endosomes at low pH. Cytoskeleton has been suggested to be involved in HPV intracellular trafficking. The poor understanding of entry and trafficking mechanism of HPV has restrained the development of new vaccines and anti-viral drugs. The genome-wide siRNA screen found gamma-secretase (J-sec) as an essential factor for HPV16 infection in epithelial cells, although the mechanism is not well characterized. This project will investigate the function of J-sec and its substrate(s) during the infectious route of HPV16 into human epithelial cells. The first aim of this study will examine the critical steps that require J-sec duing HPV16 infection by specifically measuring virus disassembly and the localization of virus particles with newly developed technologies. The steps that are inhibited by loss of J-sec activity will be investigated in relation to various cell markers. The second part of this research will examine the role of two potential substrates of J-sec in mediating HPV16 entry by proposed models. This aim may provide a mechanistic understanding of the absolute requirement of J-sec on HPV entry. Overall, the proposed aims will be valuable for the understanding of HPV16 entry process and the design of new targets for antiviral therapies.