HPV and the DNA Damage Response

描述(申请人提供)：我们研究的长期目标是确定人类乳头瘤病毒调节分化上皮细胞的生产性复制的机制。在生产性感染期间，HPV基因组在未分化的基底细胞中以低拷贝的形式稳定保持，而在高度分化的超基底细胞中进行基因组扩增和病毒粒子组装。我们最近的工作表明，HPV蛋白激活了ATM DNA损伤反应，这对于分化细胞的基因组扩增是必要的。有趣的是，在分化过程中，只有一部分ATM通路成员被HPV蛋白激活。进一步的研究表明，E7与ATM结合，这可能负责激活ATM通路成员的子集。我们还证明，HPV蛋白在分化时也会诱导低水平的caspase裂解，这也是分化细胞进行有效复制所必需的。ATM途径似乎与caspase的激活有关，因为Chk2的抑制物阻止了caspase的切割。这些观察结果构成了拟议的研究的基础，该研究旨在检查DNA损伤途径在HPV扩增分化细胞中所起的作用。在这项应用中，我们将提出以下问题：1：ATM途径的哪些成员在分化细胞的过程中对病毒的有效复制起着至关重要的作用？为什么ATM通路在细胞分化过程中对扩增很重要？E7对ATM通路的激活有何作用？其他HPV蛋白可能起到作用吗？3)ATM通路在分化诱导的半胱氨酸天冬氨酸酶的激活中起什么作用？E7是如何激活这一途径的？

DESCRIPTION (provided by applicant): The long-term goal of our studies is to determine the mechanisms by which human papillomaviruses regulate productive replication in differentiating epithelial cells. During productive infection, HPV genomes are stably maintained as low copy episomes in undifferentiated basal cells, while genome amplification and virion assembly occur in highly differentiated suprabasal cells. Our recent work has demonstrated that HPV proteins activate the ATM DNA damage response and that this is necessary for genome amplification in differentiating cells. Interestingly only a subset of ATM pathway members are activated by HPV proteins upon differentiation. Further studies indicate that E7 binds to ATM and this may be responsible for activating a subset of ATM pathway members. We have also demonstrated that HPV proteins also induce low levels of caspase cleavage upon differentiation and that this is also necessary for productive replication in differentiating cells. The ATM pathway appears to be linked to caspase activation as inhibitors of Chk2 block caspase cleavage. These observations form the basis of the proposed studies to examine the role that DNA damage pathways play in HPV amplification in differentiating cells. In this application we will ask the following questions: 1: Which members of the ATM pathway play essential roles for productive viral replication in differentiating cells? Why is ATM pathway important for amplification in differentiating cells? 2). How does E7 contribute to activation of the ATM pathway? Could other HPV proteins play a role? 3). What role does the ATM pathway play in differentiation-induced activation of caspases? How does E7 activate this pathway?