ESCRT-Related protein PTPN23 as a cofactor for HIV-1 Vpu

项目摘要 人类免疫缺陷病毒操纵宿主细胞过程，以促进病毒的合成。 这些组分必须适当地定位于亚细胞结构域以用于病毒出芽和释放。在 除了所有逆转录病毒共有的结构Gag、Pol和Env多聚蛋白外，HIV-1还编码四种 “辅助”蛋白：Vpu、Nef、Vif和Vpr，其功能是促进逃避宿主的适应性和先天性免疫应答。 免疫反应。这些病毒辅助蛋白共同参与宿主的降解和蛋白运输过程 通过作为分子衔接子与靶向宿主因子形成三元复合物，包括 由宿主“限制因子”和宿主运输组分提供的固有细胞免疫 机械.阐明宿主和病毒蛋白促进或抑制感染的机制可能 从而确定治疗干预的目标。 我们最近发现了一种新的HIV-1辅因子，ESCRT相关蛋白PTPN 23（HD-PTP）， 似乎是Vpu活动的辅助因子。PTPN 23的瞬时敲低阻止了Vpu介导的 降解BST-2并抑制病毒释放。有趣的是，PTPN 23不仅是BST-2所需的， 降解，但也为表面下调的CD 4。此外，我们以前（未发表）的研究 支持网格蛋白和网格蛋白衔接子AP-2在Vpu介导CD 4表面下调中的作用。我们 假设Vpu介导CD 4拮抗作用至少部分由内吞作用和溶酶体介导 降解，而不是完全通过ERAD样机制。 在这里，我们建议确定PTPN 23是否作为Vpu介导的CD 4降解的辅因子， 阐明Vpu与PTPN 23相互作用的分子机制。我们还将验证PTPN 23作为 在原代T细胞中Vpu活性的辅助因子，以证明在病毒感染环境中的适用性。我们将 进一步定义表面下调所必需的ESCRT途径的其它组分和/或 降解CD 4。阐明Vpu和ESCRT相关蛋白之间的分子相互作用将 确定治疗干预的目标;通过抑制Vpu的抗免疫活性，我们将使感染者敏感， 细胞检测和免疫清除。

PROJECT SUMMARY The Human Immunodeficiency Virus manipulates host cellular processes to promote synthesis of viral components, which must be appropriately localized to subcellular domains for viral budding and release. In addition to the structural Gag, Pol and Env polyproteins common to all retroviruses, HIV-1 encodes four “accessory” proteins: Vpu, Nef, Vif and Vpr, which function to promote evasion of host adaptive and innate immune responses. These viral accessory proteins co-opt host degradative and protein-trafficking processes by functioning as molecular adaptors that form ternary complexes with targeted host factors, including the intrinsic cellular immunity provided by host “restriction factors”, and components of the host trafficking machinery. Elucidation of the mechanisms by which host and viral proteins can promote or inhibit infection may lead to the identification of targets for therapeutic intervention. We have recently identified a novel HIV-1 cofactor, ESCRT-associated protein, PTPN23 (HD-PTP), which appears to function as a cofactor for Vpu activities. Transient knockdown of PTPN23 prevented Vpu-mediated degradation of BST-2 and inhibited virus release. Interestingly, PTPN23 is not only for required for BST-2 degradation, but also for surface downregulation of CD4. Furthermore, our previous (unpublished) studies support a role for clathrin and clathrin adaptor AP-2 in Vpu-mediated surface downregulation of CD4. We hypothesize that Vpu-mediated antagonism of CD4 is mediated at least in part by endocytosis and lysosomal degradation rather than exclusively by ERAD-like mechanisms. Here, we propose to determine whether PTPN23 acts as a cofactor for Vpu-mediated degradation of CD4, and elucidate the molecular mechanisms by which Vpu interacts with PTPN23. We will also validate PTPN23 as a cofactor for Vpu activities in primary T-cells to demonstrate applicability in a viral infection setting. We will further define additional components of the ESCRT pathway necessary for surface downregulation and/or degradation CD4. Elucidating the molecular interactions between Vpu and ESCRT-associated proteins will define targets for therapeutic intervention; by inhibiting Vpu's anti-immune activities we will sensitize infected cells to detection and immune clearance.