Investigating novel host factors promoting human papillomavirus infection

项目摘要/摘要： 人类乳头瘤病毒(HPV)感染了近8000万美国成年人，是导致子宫颈癌、 肛门癌和口咽癌。不幸的是，HPV疫苗一直没有得到很好的利用，没有提供 对现有感染的治疗价值，使大部分人口容易患上HPV相关癌症。至 开始感染时，HPV与一系列细胞外受体结合，并由宿主细胞内吞。人乳头瘤病毒是 然后通过一种未知的机制招募到内体中的宿主因子γ-分泌酶，使其能够 作为伴侣，将病毒衣壳蛋白L2插入到内膜上。这暴露了 L2进入细胞质，细胞质进而招募宿主因子，引导病毒沿着感染途径通过 高尔基体和细胞核。尽管HPV对人类健康有重大影响，但 了解其通过宿主细胞的特定进入途径。 初步数据提示宿主p120-catenin(P120)在调节HPV早期转运步骤中起作用 沿着一条传染路线。我们的研究小组首先通过质谱学确定了HPV-p120的相互作用， 自那以后，我们证明了这种相互作用发生在感染的早期时间点。重要的是，p120是 对于高效的HPV感染是必不可少的。进一步的实验表明，p120是将HPV靶向γ所必需的。 病毒衣壳蛋白L2跨膜插入的分泌酶。然而，由于p120是一种 胞浆因子，它必须通过跨膜蛋白与HPV相互作用。因此，我们测试了 钙粘附素-已知的结合p120和γ分泌酶的跨膜细胞黏附分子 感染。初步数据显示，除了在早期时间点结合HPV外，还需要钙粘附素 用于繁殖的HPV感染。总而言之，这些数据表明，细胞黏附钙粘附素分子，在 与胞浆p120结合，结合细胞表面的hpv，促进病毒的内吞作用。 到内吞体内。由于已知p120能将钙粘素传递给γ-分泌酶，我们进一步假设p120 将人乳头瘤病毒-钙粘附素复合体靶向内体定位的γ分泌酶，使病毒能够到达γ- 病毒蛋白L2膜插入的分泌酶。为了进一步检验这一假设，我们将阐明 钙粘附素-p120复合体促进HPV内吞作用的精确机制 启动人乳头瘤病毒感染(目标1)，以及p120如何靶向病毒的γ分泌酶进行膜插入(目标1) 2)-感染的关键步骤。基于细胞的研究、生化研究和感染研究的结合使用将是 受雇来解决手头的问题。通过这些研究获得的洞察力应该能说明内在的 细胞内转运机制。更重要的是，确定介导HPV感染的细胞因素可能 为抗击HPV感染提供新的治疗策略。

Project Summary/Abstract: Human papillomavirus (HPV) infects nearly 80 million U.S. adults, and is the primary cause of cervical, anogenital, and oropharyngeal cancers. Unfortunately, HPV vaccines have been poorly utilized and provide no therapeutic value for existing infections, leaving much of the population susceptible to HPV-related cancers. To initiate infection, HPV binds to a series of extracellular receptors and is endocytosed by the host cell. HPV is then recruited to the host factor γ-secretase in the endosome by an unknown mechanism, enabling it to act as a chaperone to insert the viral capsid protein L2 across the endosomal membrane. This exposes L2 to the cytosol, which in turn recruits host factors that direct the virus along an infectious route through the Golgi apparatus and to the nucleus. Despite HPV’s significant impact on human health, there is limited understanding of its specific entry pathway through the host cell. Preliminary data suggest a role for the host p120-catenin (p120) in regulating the early trafficking steps of HPV along an infectious route. Our research group first identified an HPV-p120 interaction via mass-spectrometry, and we have since demonstrated that this interaction occurs at early infection time-points. Importantly, p120 is essential for productive HPV infection. Further experiments suggest that p120 is required for targeting HPV to γ- secretase for insertion of the viral capsid protein L2 across the endosomal membrane. However, as p120 is a cytosolic factor, it must be interacting with HPV via a transmembrane protein. Thus, we tested the role of cadherins – transmembrane cell adhesion molecules known to bind both p120 and γ-secretase – in HPV infection. Preliminary data show that in addition to binding HPV at early time-points, cadherins are also required for productive HPV infection. Together, these data suggest the cell-adhesion cadherin molecule, in conjunction with cytosolic p120, binds to HPV at the cell surface, and promotes endocytosis of the virus to the endosome. As p120 is known to deliver cadherin to γ-secretase, we further hypothesize that p120 targets the HPV-cadherin complex to endosome-localized γ-secretase so that the virus can reach γ- secretase for membrane insertion of the viral protein L2. To further test this hypothesis, we will elucidate the precise mechanism by which the cadherin-p120 complex promotes endocytosis of HPV to the endosome to initiate HPV infection (Aim 1), and how p120 then targets the virus to γ-secretase for membrane insertion (Aim 2) – a critical step of infection. The combined use of cell-based, biochemical, and infection studies will be employed to tackle the questions at hand. Insights gained through these studies should illuminate intrinsic intracellular transport mechanisms. More importantly, identifying the cellular factors mediating HPV infection may provide new therapeutic strategies to combat HPV infections.