THE ROLE OF HIV-1 VPU IN THE REGULATION OF CD40

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 该项目的总体目标是了解HIV-1蛋白VPU在HIV发病机制中的作用。最初的目的是了解VPU如何调节细胞因子受体CD40的表达。 我们的研究表明，VPU对CD40的影响是由于其他途径的下游调节所致。因此，我们利用蛋白质组学的方法，以一种依赖于βTrCP的方式来鉴定受VPU影响的新的细胞蛋白，并将BST-2确定为VPU的一个重要靶点。这一点很重要，因为BST-2最近被确定为一种宿主抗病毒因子，限制艾滋病毒从感染细胞中释放。BST-2被重新命名为tetherin，独立的研究证实了我们的发现，VPU拮抗BST-2。因此，我们重新将项目目标的重点放在研究VPU介导的BST-2下调的机制和生物学后果上，并在这方面取得了重大进展。我们发现VPU通过内体/溶酶体途径与BST-2相互作用并靶向降解BST-2，并且βTrCP是降解所必需的，并发表了这项工作。我们在以下方面取得了更多进展：1)定位克服病毒出口BST-2限制所必需的VPU区域；2)表征泛素在VPU介导的BST-2降解中的作用；3)确定参与病毒粒子拴系或作为VPU功能接头的BST-2结合伙伴。这一进展使我们能够提交新的R01申请《VPU药物降解BST-2的特性》。我们的BST-2试剂也被用于合作研究KSHV K5蛋白对BST-2的拮抗作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall goal of this project is to understand the role of the HIV-1 protein Vpu in HIV pathogenesis. The original aim was to understand how Vpu modulates expression of the cytokine receptor CD40. Our studies showed that Vpu's effect on CD40 was due to downstream modulation of other pathways. We thus performed proteomics to identify novel cellular proteins affected by Vpu in a beta TrCP-dependent manner, and identified BST-2 as a significant Vpu target. This was important, since BST-2, was recently identified as a host antiviral factor that restricts the release of HIV from infected cells. BST-2 was renamed tetherin and independent studies confirmed our finding that Vpu antagonizes BST-2. We thus refocused our project goals to investigate the mechanisms and biological consequences of Vpu-mediated BST-2 downregulation and have made significant progress in this regards. We found that Vpu interacts with and targets BST-2 for degradation by an endosomal/lysosomal pathway and that beta TrCP is required for degradation and have published this work. We have made additional progress in the following areas i) mapping Vpu regions necessary for overcoming BST-2 restriction of viral egress; ii) characterizing the role of ubiquitin in Vpu-mediated BST-2 degradation; iii) identifying BST-2 binding partners involved in virion tethering or acting as adapters for Vpu function. This progress has allowed us submit a new R01 application "Characterization of Vpu-medicated Degradation of BST-2". Our BST-2 reagents were also used in collaborative work to examine BST-2 antagonism by the KSHV K5 protein that is now published.