The Role of Caspase Activation in the Differentiation-Dependent Life Cycle of HPV

Caspase 激活在 HPV 分化依赖性生命周期中的作用

• 批准号: 8122505
• 负责人: CARY A MOODY
• 金额: $ 24.9万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-20 至 2013-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8122505
• 关键词: Caspase; Human Papillomavirus; Life Cycle Stages; Role

High-risk human papillomaviruses (HPV) are the causative agents of cervical cancer. The life cycle of HPV Is tied to the differentiation status of its host cell, the keratinocyte. Differentiation triggers the productive phase of the life cycle, which includes viral genome amplification, late gene expression and virion production. In contrast to normal cells, which exit the cell cycle upon differentiation, expression of the HPV E6 and E7 proteins maintain a subset of cells active in the cell cycle largely through degradation of p53 and pRb, respectively The long-term goal of this project is to understand the mechanisms that regulate the activation of differentiation-dependent viral events. Toward this end, I have demonstrated that HPV31 stimulates a low level of caspase activation upon differentiation that is characteristic of the mitochondrial apoptotic pathway and necessary for amplification of viral genomes through cleavage of the viral replication protein E1. In addition, I have recently found that HPV induces an ATM-dependent DNA damage response in differentiating cells, which is necessary for efficient viral genome amplification, as well as caspase activation through the ATM target Chk2. Based on the finding that caspase activation, as well as Chk2 activation, can be stimulated by both E6 and E7, and the identification of caspase cleavage sites in several HPV proteins, I hypothesize that the HPV proteins E6 and E7 induce caspase activation through a DNA damage response to activate late viral events. Specific aims to test this hypothesis are: 1) Identify the mechanism(s) by which HPV activates caspases in differentiating cells by examining the effect of E6 and E7 on the DNA damage response and alteration of mitochondrial membrane integrity, as well as by performing a mutational analysis of E6 and E7 to identify domains that are necessary for Chk2 activation and caspase activation; 2) Determine how caspase cleavage of HPV proteins contributes to differentiation-dependent events in the life cycle by using in vitro and in vivo studies. Delineating the pathway by which E6 and E7 mediate activation of a DNA damage response to lead to caspase activation will offer insight as to how HPV modulates apoptotic machinery to facilitate not only the viral life cycle, but possibly transformation as well.

高危人乳头瘤病毒（HPV）是宫颈癌的病原体。 HPV的生命周期是 与其宿主细胞角质形成细胞的分化状态有关。差异化触发生产阶段 生命周期，包括病毒基因组扩增、晚期基因表达和病毒体产生。在 与分化后退出细胞周期的正常细胞相比，HPV E6 和 E7 的表达 蛋白质主要通过 p53 和 pRb 的降解来维持细胞周期中活跃的细胞子集， 该项目的长期目标是了解调节激活的机制 分化依赖性病毒事件。为此，我已经证明 HPV31 会刺激低 分化时 caspase 激活水平是线粒体凋亡途径的特征 并且是通过切割病毒复制蛋白 E1 来扩增病毒基因组所必需的。在 此外，我最近发现 HPV 会诱导 ATM 依赖性 DNA 损伤反应 分化细胞，这是有效病毒基因组扩增以及半胱天冬酶激活所必需的 通过 ATM 目标 Chk2。基于发现 caspase 激活以及 Chk2 激活可以 受到 E6 和 E7 的刺激，并且鉴定了几种 HPV 蛋白中的 caspase 切割位点，I 假设 HPV 蛋白 E6 和 E7 通过 DNA 损伤反应诱导 caspase 激活 激活晚期病毒事件。检验该假设的具体目标是： 1) 确定以下机制： HPV 通过检查 E6 和 E7 对 DNA 损伤的影响来激活分化细胞中的半胱天冬酶 线粒体膜完整性的反应和改变，以及通过进行突变分析 E6 和 E7 来识别 Chk2 激活和 caspase 激活所需的结构域； 2） 确定 HPV 蛋白的半胱天冬酶裂解如何促进生命中的分化依赖性事件 通过体外和体内研究进行循环。描述 E6 和 E7 介导激活的途径 导致 caspase 激活的 DNA 损伤反应将提供有关 HPV 如何调节细胞凋亡的见解 机器不仅可以促进病毒的生命周期，还可能促进转化。