HIV-1 Vpr Induces G2 Cell Cycle Arrest and Apoptosis

描述(由申请人提供)：该提案构成了研究HIV-1 vpr基因产物的作用的续展申请。这里提出的研究的总体目标是了解VPR的各种功能之间的相互作用，以及它们如何在HIV-1的发病机制中做出贡献。这里要提出的假设是，VPR在HIV-1的复制和发病机制中起着关键作用。HIV-1 vpr基因产物是一种96个氨基酸的蛋白质，对病毒复制很重要，可能对HIV-1的致病作用至关重要。VPR在细胞感染后表达，也被发现包装在病毒粒子中。1995年，在这笔赠款的初始资助期开始时，我们是第一批描述VPR蛋白的新表型的人之一，通过这种蛋白，感染了表达VPR的HIV-1的细胞在细胞周期的G2阶段发生停滞。我们集中精力进一步研究VPR蛋白的这一独特功能。我们已经证明，细胞周期停滞是VPR在进化上高度保守的特性。此外，我们还发现VPR诱导的细胞周期停滞伴随着细胞的凋亡。其他研究人员报告说，VPR增强了病毒的产生，并参与了细胞因子的调节。在过去的资助期间，我们做了一个重要的观察，即包装成病毒粒子的VPR能够诱导细胞周期停滞和细胞凋亡，而不依赖于病毒生命周期中的后续事件。最近，我们观察到病毒粒子Vpr对于从未整合的病毒DNA中表达至关重要。因此，结合这些结果，这些结果表明VPR在HIV-1的发病机制中起着重要作用，它通过病毒基因表达的即刻上调和对T细胞代谢的长期影响而发挥作用。 在之前的资助期间，我们生成了大量关于VPR作用的初步数据，开发了一些用于评估VPR功能的独特分析方法，并开发了使我们能够有效地开展VPR作用机制的进一步研究的试剂。其具体目的是：1)进一步研究VPR介导的细胞周期停滞和细胞凋亡。目的2)研究新近报道的VPR介导的HIV-1DNA反式激活过程。目的3)进一步阐明VPR在病毒致病中的作用。

DESCRIPTION (provided by applicant): This proposal constitutes a renewal application to study the role of the HIV-1 Vpr gene product. The overall goal of the studies proposed here is to understand the interaction between the various functions of Vpr and how they contribute to the pathogenesis of HIV-1. The hypothesis to be addressed here is that Vpr plays a critical role for HIV-1 replication and pathogenesis. The HIV-1 Vpr gene product is a 96 amino acid protein, which is important for viral replication and likely to be critical for HIV-1 pathogenesis. Vpr is expressed following infection of cells and is also found packaged in virions. In 1995, at the beginning of the initial funding period of this grant, we were among the first to describe a novel phenotype of the Vpr protein whereby cells infected by HIV-1 expressing Vpr undergo arrest at the G2 phase of the cell cycle. We focused our efforts on further characterizing this unique function of the Vpr protein. We have shown that cell cycle arrest is a highly evolutionarily conserved property of Vpr. In addition, we found that cell cycle arrest induced by Vpr is followed by apoptosis of the arrested cells. Other investigators have reported that Vpr enhances virus production and is involved in cytokine regulation. During the past funding period we made the important observation that Vpr that is packaged into virions is capable of inducing both cell cycle arrest and apoptosis independent of subsequent events in the viral lifecycle. Recently, we made the observation that virion Vpr is critical for expression from unintegrated viral DNA. Thus, in combination these results indicate that Vpr plays an important role in HIV-1 pathogenesis through the immediate early upregulation of viral gene expression and longer term effects upon T-cell metabolism. During the previous funding periods we have generated a considerable amount of preliminary data about Vpr action, developed a number of unique assays for assessment of Vpr function, and developed reagents which will allow us to effectively carry forward further studies on the mechanism of Vpr action. The specific aims are: Aim 1) To further characterize cell cycle arrest and apoptosis mediated by Vpr. Aim 2) To characterize the newly described process of Vpr mediated transactivation of unintegrated HIV-1 DNA. Aim 3) To further characterize the role of Vpr in viral pathogenesis.