HIV-1 INDUCES G2/M CELL CYCLE ARREST

已经提出了各种机制来解释免疫 艾滋病的功能障碍最终导致CD 4 + T细胞的损失，包括 细胞因子介导的合胞体形成、细胞凋亡和细胞因子调节。 我们最近的研究结果提出了一种新的T细胞功能障碍假说。我们 使用了一种携带新型细胞的人类免疫缺陷病毒1型（HIV-1）， 表面报告基因，鼠thy 1.2，以区分感染者和 未感染的细胞。我们发现受感染的细胞， 无论是来自细胞系还是原代T细胞， 在细胞周期中，它被阻滞在G2/M期。之一 HIV-1基因vpr涉及许多功能，包括 反式激活、核靶向和潜伏HIV-1的再激活。 我们证明，细胞生长的停滞可以归因于 HIV-1的vpr基因产物，因为该基因的突变允许细胞周期 受感染细胞的发展。此外，通过瞬时转染， 我们的实验表明，vpr单独表达会诱导细胞周期 在SupT 1 T细胞和HeLa细胞中的停滞。使用不同的报告器 系统，荧光素酶，我们研究了HIV G2期阻滞的后果- 1次重复。我们的研究结果表明，HIV-1前病毒并不维持在 这是由于受感染细胞的选择性生长不利。突变 VPR导致感染的维持。因此，vpr的表达阻止了 建立慢性HIV-1感染。这些结果有两个 与HIV-1发病机制相关的预测：1）HIV-1 感染一般不会导致持续的慢性感染 2）受感染的T细胞将无法接受 由于G2/M停滞导致的克隆扩增，导致免疫缺陷。 功能障碍我们建议在这里扩展我们的初步研究结果， 进一步了解其作用机制。 具体目标是： 1.确定G2/M期阻滞表型与 vpr基因的其他观察功能。结构功能 将通过遗传学方法研究它们之间的关系。 2.比较HIV-1、HIV-2和HIV-1vpr相关基因的功能， 猴免疫缺陷病毒（SIV）在细胞周期停滞方面的作用。我们 还将比较Vpr的功能与进化上的 vpx保守基因。

Various mechanisms have been proposed to account for the immune dysfunction in AIDS ultimately leading to loss of CD4+ T-cells, including envelope-mediated syncytium formation, apoptosis and cytokine modulation. Our recent results suggest a novel hypothesis forT-cell dysfunction. We used a human immunodeficiency virus type 1 (HIV-1) bearing a novel cell surface reporter gene, murine thy 1.2, to distinguish infected from uninfected cells in the same population. We show that infected cells, both from cell lines and primary T-cells, are unable to progress normally through the cell cycle and become arrested in the G2/M phase. One of the HIV-1 genes, vpr, has been implicated in a number of functions, including trans-activation, nuclear targeting and re-activation of latent HIV-1. We demonstrate that the arrest of cell growth can be attributed to the vpr gene product of HIV-1, as mutation of this gene allows cell cycle progression of the infected cells. Furthermore, by transient transfection assays, we show that expression of vpr alone will induce cell cycle arrest in SupT1 T-cells and HeLa cells. Using a different reporter system, luciferase, we investigate the consequences of G2 arrest for HIV- 1 replication. Our results show that the HIV-1 provirus is not maintained due to the selective growth disadvantage of infected cells. Mutation of vpr results in maintenance of infection. Thus, expression of vpr prevents the establishment of a chronic HIV-1 infection. These results have two predictions that are relevant to HIV-1 pathogenesis: 1) that HIV-1 infection does not generally lead to a chronic infection with persistence of provirus; and 2) that infected T-cells would be unable to undergo clonal expansion as a result of G2/M arrest, with consequences for immune dysfunction. We propose here to extend our initial findings to develop further insights into its mechanism of action. The Specific Aims are to: 1. Determine the relationship between the G2/M arrest phenotype and other observed functions of the vpr gene. Structure-function relationships will be investigated through genetic approaches. 2. Compare the functions of vpr-related genes from HIV-1, HIV-2 and simian immunodeficiency virus (SIV) in regards to cell cycle arrest. We will also compare the functions of Vpr with those of the evolutionarily conserved vpx gene.