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物，这一过程被称为“病毒学结合”。 突触形成。这一过程让人想起“免疫突触”的形成，在此期间， CD 4 + T细胞迅速破坏肌动蛋白细胞骨架、微管组织中心（MTOC）和细胞因子- 含有朝向抗原呈递细胞的囊泡。免疫过程中CD 4 + T细胞的极化 突触的形成依赖于RHO家族的GT3 CDC 42，这是一种在突触形成中起关键作用的分子开关。 真核细胞极性的建立。 我们现在已经观察到，CDC 42对于HIV-1在几种T细胞系中的有效传播至关重要 和原代细胞中。然而，我们的数据也意味着，CDC 42是完成一个单一的， 循环复制。总之，我们的观察结果表明CDC 42参与了HIV-1的细胞间传播。 CDC 42通过效应子刺激膜延伸的形成，如丝状伪足， 介导肌动蛋白细胞骨架的极化，HIV-1可以利用丝状伪足桥从细胞中传播 到细胞。因此，我们的数据让我们提出了一个工作模型，其中CDC 42对形成 细胞间延伸，促进HIV-1在CD 4 + T细胞之间的转移。为了支持这一模式，我们 已经观察到CDC 42是MOLT-3形成HIV-1诱导的膜延伸所必需的 细胞另一种工作模式是，HIV-1病毒粒子的两极化运输需要CDC 42 病毒学突触的组成部分。 我们建议直接研究CDC 42在HIV-1细胞间传播和病毒学中的作用。 突触形成，并确定HIV-1是否调节CDC 42的活性。我们亦建议 研究CDC 42效应物在调节HIV-1局部肌动蛋白组装和极化运输中的作用 蔓延在这些效应器中，F-BAR蛋白与肌动蛋白聚合机制连接， F-BAR蛋白PACSIN 2，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CDC 42效应，包括CDC 42调节的肌动蛋白， 聚合酶FMNL 1和一个控制极化胞吐作用的假定的CDC 42效应子，在 HIV-1复制。 拟议的研究有可能产生新的基本见解的机制， 重要但知之甚少的HIV-1传播方式。特别重要的是， 鉴定出CDC 42下游的激酶对HIV-1传播至关重要，因为蛋白激酶 构成了最重要的药物靶点之一。

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.