Role of cell polarity regulators in HIV spreading

摘要 HIV-1感染的T细胞可以与未感染的T细胞形成稳定的结合，这一过程被称为病毒学 突触“队形”。这一过程让人联想到免疫突触的形成，在这个过程中， CD4T细胞迅速极化肌动蛋白细胞骨架、微管组织中心(MTOC)和细胞因子-- 含有通向抗原提呈细胞的小泡。免疫过程中CD4T细胞的极化 突触的形成依赖于Rho家族GTP酶CDc42，这是一个在细胞周期中起关键作用的分子开关 真核细胞中极性的建立。 我们现在已经观察到，CDC42对于HIV-1在几种T细胞系中的有效传播至关重要 在原代细胞中。然而，我们的数据也暗示，对于完成单个 复制周期。总之，我们的观察结果表明，CDC42参与了HIV-1的细胞间传播。 Cdc42通过以下效应器刺激膜延伸的形成，如丝状伪足 调节肌动蛋白细胞骨架的极化，HIV-1可以利用丝足桥从细胞传播 转到牢房。因此，我们的数据让我们提出了一个工作模型，在该模型中，CdC42对 促进HIV-1在CD4T细胞之间转移的细胞间延伸。为了支持这一模式，我们 已经观察到，在HIV-1诱导的MOLT-3的膜延伸形成过程中需要cdc42。 细胞。另一种工作模式是cdc42对于HIV-1病毒粒子的极化运输是必需的。 病毒突触的组成部分。 我们建议直接研究CDC42在HIV-1细胞间传播和病毒学中的作用 突触的形成，并确定HIV-1是否调节CDC42的活性。我们还建议 研究在HIV-1中调节局部肌动蛋白组装和极化运输的CDC42效应器的作用 正在扩散。在这些效应器中，有F-bar蛋白，它与肌动蛋白聚合机制相连，也是如此 F-bar蛋白PACSIN2，我们最近发现它与HIV-1的细胞间传播有关。 值得注意的是，我们的初步结果表明，某些cdc42效应器，包括由cdc42调节的肌动蛋白 聚合酶FMNL1和一个可能的控制极化胞吐的CDC42效应器，在 HIV-1复制。 拟议中的研究有可能对AND的机制产生根本性的新见解。 重要但知之甚少的艾滋病毒-1传播方式。特别重要的是 鉴定CDC42下游的一种对HIV-1传播至关重要的激酶，因为蛋白激酶 构成了最重要的药物靶标之一。

ABSTRACT HIV-1-infected T cells can form stable conjugates with non-infected T cells in a process known as “virological synapse” formation. This process is reminiscent of the formation of an “immunological synapse”, during which CD4+ T cells rapidly polarize the actin cytoskeleton, the microtubule-organizing center (MTOC), and cytokine- containing vesicles towards antigen-presenting cells. The polarization of CD4+ T cells during immunological synapse formation depends on the RHO family GTPase CDC42, a molecular switch that has a key role in the establishment of polarity in eukaryotic cells. We have now observed that CDC42 is critical for the efficient spreading of HIV-1 in several T cell lines and in primary cells. However, our data also imply that CDC42 is dispensable for the completion of a single cycle of replication. Together, our observations implicate CDC42 in the cell-to-cell transmission of HIV-1. CDC42 stimulates the formation of membrane extensions, such as filopodia, through effectors that mediate the polarization of the actin cytoskeleton, and HIV-1 can exploit filopodial bridges to spread from cell to cell. Thus, our data let us to propose a working model in which CDC42 is crucial for the formation of intercellular extensions that facilitate the transfer of HIV-1 between CD4+ T cells. In support of this model, we have observed that CDC42 is required for the formation of HIV-1-induced membrane extensions by MOLT-3 cells. An alternative working model is that CDC42 is required for the polarized trafficking of HIV-1 virion components to the virologic synapse. We propose to directly examine the roles of CDC42 in HIV-1 cell-to-cell transmission and virological synapse formation, and to determine whether HIV-1 regulates the activity of CDC42. We also propose to examine the roles of CDC42 effectors that regulate localized actin assembly and polarized trafficking in HIV-1 spreading. Among these effectors are F-BAR proteins that connect to actin polymerization machinery, as does the F-BAR protein PACSIN2, which we have recently implicated in the cell-to-cell transmission of HIV-1. Notably, our preliminary results indicate that certain CDC42 effectors, including the CDC42-regulated actin polymerase FMNL1 and a putative CDC42 effector that controls polarized exocytosis, have crucial roles in HIV-1 replication. The proposed studies have the potential to yield fundamental new insights into the mechanism of an important but poorly understood mode of HIV-1 transmission. Of particular significance would be the identification of a kinase downstream of CDC42 as being critical for HIV-1 spreading, since protein kinases constitute one of the most important groups of drug targets.