Regulation of HIV-1 by Rad51 in CNS cells

描述(申请人提供)：感染HIV-1的中枢神经系统可触发一系列防御机制，旨在阻止病毒基因组在其生命周期的不同阶段表达。反过来，HIV-1通过其附属蛋白，尤其是Tat，进化出几个调节事件，以克服细胞防御途径，并通过一系列不同的调节事件诱导对细胞的最大损害，同时确保感染细胞中有生产力的病毒生命周期。近年来，HIV-1感染对宿主细胞动态平衡的影响越来越受到关注，更具体地说，HIV-1与通过同源和非同源DNA修复控制染色体完整性的细胞通路的相互作用。虽然HIV-1VPR在影响DNA损伤中的作用已有很好的文献记载，但最近的观察(如图所示)指出，TAT在原代小胶质细胞和星形胶质细胞中诱导RAD51表达的能力，这两种细胞类型在艾滋病的神经发病机制中发挥重要作用。这一观察结果证实了感染研究的结果，该研究表明，在培养的HIV-1感染的小胶质细胞和星形胶质细胞中，以及在患有HIV脑炎的艾滋病脑中，RAD51水平增加。RAD51是同源重组修复途径的主要调节者，与其他细胞蛋白协同确保染色体的完整性。显然，RAD51的非计划激活可能会对几个细胞通路产生不利影响，在某些情况下甚至会损害染色体的完整性。有趣的是，Tat蛋白对RAD51的诱导可能对小胶质细胞和星形胶质细胞中HIV-1启动子的活性具有正反馈作用。在这方面，我们的初步数据表明，RAD51可能会招募HIV-1的两个调节因子--核因子-B和细胞周期蛋白T1，以刺激中枢神经系统细胞中的LTR。所有这些观察为我们提供了一个理论基础，我们假设HIV-1通过其反式激活因子TAT与宿主重组修复调节因子RAD51的相互作用创造了一种条件，导致小胶质细胞、星形胶质细胞和可能的巨噬细胞中的HIV-1启动子被激活，并改变有利于HIV-1的宿主重组修复途径。在这一应用中，我们寻求支持，以启动一系列整合良好的分子、病毒学和细胞学研究，以破译与HIV-1和宿主DNA修复机制的交叉通信相关的分子事件，并根据我们的观察，开发一种策略，以抑制支持病毒感染的细胞中的HIV-1基因表达和激活。在我们的研究中，我们的分子发现与HIV-1神经发病机制的相关性将在每个阶段通过使用来自蜂房患者的独特大脑标本(由曼哈顿脑库提供)来验证。因此，通过这种新的综合方法，我们的研究将提供与HIV-1/CNS疾病相关的重要信息，可用于改进目前治疗艾滋病患者神经系统疾病的方法。

DESCRIPTION (provided by applicant): Infection of the central nervous system with HIV-1 can trigger a cascade of defense mechanisms that are aimed at blocking expression of the viral genome at various stages of its life cycle. In turn, HIV-1 has evolved several regulatory events via its accessory proteins, more notably Tat, to overcome the cellular defense pathways and through a series of diverse modulatory event induces maximum damage to the cells while ensuring a productive viral life cycle in the infected cells. Recently, much attention has been focused on the impact of HIV-1 infection on host cell homeostasis, more specifically the interaction of HIV-1 with cellular pathways that control chromosomal integrity via homologous and non-homologous DNA repair. While the role of HIV-1 Vpr in affecting DNA damage is well documented, recent observations (shown here) point to the ability of Tat in the induction of Rad51 expression in primary microglia and astrocytes, the two cell types that play an important role in neuropathogenesis of AIDS. This observation corroborates the results from infection studies showing increased levels of Rad51 in HIV-1 infected microglia and astrocytes in culture and in AIDS brain with HIV encephalitis. Rad51 is the major regulator of the homologous recombination repair pathway that in coordination with other cellular proteins ensures chromosomal integrity. Evidently, unscheduled activation of Rad51 may have an adverse impact on several cellular pathways and in some instances even compromise chromosomal integrity. Interestingly, induction of Rad51 by Tat protein may have a positive feedback effect on HIV-1 promoter activity in microglia and astrocytes. In this respect, our preliminary data point to the possible recruitment of NF-B and cyclin T1, the two regulators of HIV-1, by Rad51 for stimulation of the LTR in CNS cells. All these observations provide a rationale for us to hypothesize that the reciprocal interaction of HIV-1 through its transactivator, Tat, with the host recombination repair regulator, Rad51 creates a condition that leads to activation of the HIV-1 promoter in microglia, astrocytes and possibly macrophages, and alters host recombination repair pathways in favor of HIV-1. In this application, we seek support to launch a series of well-integrated molecular, virological, and cellular studies to decipher the molecular events associated with cross-communication of HIV-1 and host DNA repair machinery and develop a strategy, based on our observations, to inhibit HIV-1 gene expression and activation in cells that support viral infection. Throughout our studies the relevance of our molecular discoveries to the neuropathogenesis of HIV-1 will be verified at every stage through the use of a unique collection of brain specimens from HIVE patients (provided by the Manhattan Brain Bank). Thus, through this novel integrated approach, our studies will provide important information relevant to HIV-1/CNS diseases that can be used to improve the current method for treatment of AIDS patients with neurological disorders.