Roles of Macropinocytosis in HIV-1 infection of CD4+ T Cells

巨噬细胞吞噬在HIV-1感染CD4+T细胞中的作用 项目总结： 宿主细胞进入是HIV-1复制周期的第一步，HIV-1是艾滋病的病原体。虽然受体 在病毒进入过程中，病毒包膜糖蛋白的结合和随后的病毒-细胞融合已经被 详细描述，这些事件的亚细胞位置仍有待确定。尤其是，尽管 CD4+T淋巴细胞作为HIV-1自然宿主细胞类型的重要性，病毒颗粒内吞作用的贡献 对HIV-1感染对CD4+T细胞的影响仍知之甚少。之前关于HIV-1进入T细胞的研究已经 主要集中在网状蛋白介导的内吞作用和细胞表面融合。不过，我们团队最近 发现原始的CD4+T细胞参与了强大的巨噬细胞吞噬作用，这是一种大规模的、不依赖于笼蛋白的 内吞作用的形式。重要的是，我们的初步数据表明，药物抑制 巨噬细胞吞噬抑制HIV-1颗粒的内化和原发人类的生产性感染 CD4+T细胞。相比之下，相同的治疗方法不会影响HIV感染常用的CD4+T细胞 排队。这些结果表明，巨噬细胞进入是一种迄今被忽视的HIV-1进入方式 导致人类原代CD4+T细胞的感染。有趣的是，我们的初步研究还显示， 病毒内化完成后抑制巨噬细胞吞噬也会阻止病毒编码的表达 基因，这表明巨噬细胞吞噬作用在生产性HIV感染中有另一个后来的作用，这是可以分离的 来自病毒的内化。在目前的应用中，我们建议确定巨饮细胞增多在 原代CD4+T细胞的生产性感染。我们的长期目标是全面描述细胞机制， 促进艾滋病毒-1感染，并利用所获得的知识制定抗病毒战略。我们的中央 这一应用中的假设是，原代人类CD4+T细胞中的巨噬细胞吞噬作用有助于 感染是HIV-1进入的主要途径，也是维持允许感染所必需的细胞功能 病毒的环境。为了验证这一假设，我们计划确定：1)巨噬细胞 内化有助于艾滋病毒高效地进入原代人类CD4+T细胞；2) 环境受体相互作用促进HIV-1巨噬细胞吞噬；3)巨噬细胞小体的影响 环境对HIV-1进入的影响；以及4)内化后巨噬细胞吞噬功能的性质 生殖性感染。这项提案中概述的实验结果可能会填补这一知识空白。 在我们对艾滋病毒-1进入的理解中，艾滋病毒-1复制周期的一个基本方面，并帮助我们 或者改进针对病毒进入和在CD4+T细胞中建立生产性感染的抗病毒策略。

Title: Roles of Macropinocytosis in HIV-1 infection of CD4+ T Cells Project Summary: Host cell entry is the first step in the replication cycle of HIV-1, the causative agent of AIDS. Although receptor binding of viral Env glycoprotein and subsequent virus-cell fusion during the virus entry process have been described in detail, subcellular locations of these events remain to be determined. In particular, despite the importance of CD4+ T lymphocytes as a natural host cell type for HIV-1, the contribution of virion endocytosis to HIV-1 infection of CD4+ T cells remains poorly understood. Previous studies of HIV-1 entry into T cells have largely focused on clathrin-mediated endocytosis and cell surface fusion. However, our team recently discovered that primary CD4+ T cells engage in robust macropinocytosis, a large-scale, clathrin-independent form of endocytosis. Importantly, our preliminary data indicate that pharmacological inhibition of macropinocytosis blocks both internalization of HIV-1 particles and productive infection in primary human CD4+ T cells. In contrast, the same treatment does not affect HIV infection of a commonly used CD4+ T cell line. These results suggest that the macropinocytic entry is a hitherto overlooked mode of HIV-1 entry that contributes to infection of primary human CD4+ T cells. Interestingly, our preliminary study also showed that inhibition of macropinocytosis after completion of virus internalization also blocks expression of virus-encoded genes, suggesting that macropinocytosis has another later role in productive HIV infection, which is separable from virus internalization. In the current application, we propose to determine the roles of macropinocytosis in productive infection of primary CD4+ T cells. Our long-term goal is to fully describe cellular mechanisms that promote HIV-1 infection and to use the obtained knowledge for developing antiviral strategies. Our central hypothesis in this application is that macropinocytosis in primary human CD4+ T cells contributes to productive infection as a major HIV-1 entry pathway and as a cellular function necessary for maintaining a permissive environment for the virus. To test this hypothesis, we plan to determine: 1) the extent to which macropinocytic internalization contributes to productive HIV entry into primary human CD4+ T cells; 2) the roles played by Env-receptor interactions in promoting HIV-1 macropinocytosis; 3) the influence of macropinosome environment on HIV-1 entry; and 4) the nature of post-internalization macropinocytosis function that promotes productive infection. The outcomes of the experiments outlined in this proposal will likely fill the knowledge gap in our understanding of HIV-1 entry, a fundamental aspect of the HIV-1 replication cycle, and help us develop or improve antiviral strategies that target virus entry and establishment of productive infection in CD4+ T cells.