Regulation of HIV-1 by Rad51 in CNS cells

描述（由申请人提供）：HIV-1感染中枢神经系统可触发一系列防御机制，旨在阻断病毒基因组在其生命周期各个阶段的表达。反过来，HIV-1通过其辅助蛋白，更值得注意的是达特，进化出几种调节事件，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伤，同时确保感染细胞中的生产性病毒生命周期。最近，很多注意力集中在HIV-1感染对宿主细胞稳态的影响上，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途径的相互作用。虽然HIV-1 Vpr在影响DNA损伤中的作用已被充分证明，但最近的观察（如图所示）指出达特在诱导原代小胶质细胞和星形胶质细胞中Rad 51表达的能力，这两种细胞类型在AIDS的神经发病机制中起重要作用。这一观察结果证实了感染研究的结果，感染研究显示培养的HIV-1感染的小胶质细胞和星形胶质细胞中以及患有HIV脑炎的AIDS脑中Rad 51水平增加。Rad 51是同源重组修复途径的主要调节因子，与其他细胞蛋白协调确保染色体完整性。显然，Rad 51的非计划性激活可能对几种细胞途径产生不利影响，在某些情况下甚至损害染色体完整性。有趣的是，由达特蛋白诱导的Rad 51可能对小胶质细胞和星形胶质细胞中的HIV-1启动子活性具有正反馈效应。在这方面，我们的初步数据指出，可能的招聘NF-B和细胞周期蛋白T1，两个调节HIV-1，由Rad 51刺激的LTR在中枢神经系统细胞。所有这些观察结果为我们假设HIV-1通过其反式激活因子达特与宿主重组修复调节因子Rad 51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HIV-1启动子的激活，并改变了有利于HIV-1的宿主重组修复途径提供了依据。在这项申请中，我们寻求支持，以启动一系列整合良好的分子，病毒学和细胞研究，以破译与HIV-1和宿主DNA修复机制交叉通讯相关的分子事件，并根据我们的观察结果制定一项策略，以抑制HIV-1基因表达和支持病毒感染的细胞中的激活。在整个研究过程中，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HIVE患者的独特脑标本（由曼哈顿脑库提供）进行验证。因此，通过这种新的综合方法，我们的研究将提供有关HIV-1/CNS疾病的重要信息，可用于改善目前治疗AIDS患者神经系统疾病的方法。 公共卫生相关性：即使在HAART时代，艾滋病痴呆综合征、轻微运动认知障碍和周围神经病变在HIV-1相关神经系统疾病（HAND）中仍然很重要。新的宿主-病毒相互作用途径的鉴定可以提供关于AIDS/CNS疾病的发病机制的重要信息，并促进更有效的治疗策略的发展。

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. PUBLIC HEALTH RELEVANCE: AIDS dementia complex, minor motor cognitive disorders and peripheral neuropathies remain significant in HIV-1 associated neurological disorders (HAND) even in the HAART era. The identification of novel host-viral interaction pathways can provide important information regarding the pathogenesis of AIDS/CNS disease and promote the development of more effective therapeutic strategies.