Vpr Revisited

描述（由申请方提供）：HIV-1 Vpr是一种由所有慢病毒编码的核病毒体包装辅助蛋白。此外，SIV/HIV-2编码Vpx，其保持紧密的序列相似性。Vpr的标志是它诱导G2/M细胞周期停滞。理解Vpr/Vpx在病毒复制和发病机制中的作用的关键是鉴定与它们相互作用的细胞蛋白。包括我们在内的几个研究小组最近报道了一种细胞复合物的鉴定，Vpr和Vpx可能与这种复合物相互作用，并通过这种复合物发挥作用。该复合物是由DDB 1/DCAF 1/CUL 4A/ROC 1组成的E3泛素连接酶。该复合物通过介导细胞蛋白质的破坏来调节基因组DNA复制和受损DNA修复，所述细胞蛋白质包括DNA复制许可因子CDT 1、STAT 1和STAT 2以及其他尚未鉴定的底物。与E3泛素连接酶的相互作用的鉴定提出了一个统一的解释Vpr如何介导其影响，并提供了一个框架，以阐明Vpr在HIV-1发病机制中发挥的作用。其他病毒编码靶向该复合物的蛋白质，将其用作诱导STAT蛋白质降解以抑制I型干扰素应答的手段。我们将确定Vpr是否通过其与复合物的相互作用来将细胞阻滞在G2期，诱导凋亡并激活DNA损伤信号通路。此外，将鉴定和表征与Vpx和DCAF 1结合的细胞蛋白。第三，该项目将测试他们的假设，即Vpr/Vpx在抑制对病毒的先天免疫反应中发挥作用。在过去的几年里，先天免疫已经成为一个非常感兴趣的话题。该项目将确定Vpr/Vpx是否可能构成另一种此类机制。细胞具有抵抗病毒感染的机制。这些机制非常有趣，因为它们为开发抗病毒药物提供了新的途径。病毒已经进化出逃避这些所谓的先天免疫机制的方法。例如，HIV产生一种称为病毒体感染因子（VIF）的蛋白质，该蛋白质使血细胞产生的抗病毒蛋白质之一失活。在这个项目中，我们将研究一种称为病毒蛋白R（VPR）的HIV蛋白，它可能是病毒避免先天免疫机制的另一种手段。当细胞感染HIV时，Vpr会产生，正如我们最近发现的那样，它与一种称为受损DNA结合蛋白1（DDB 1）的细胞蛋白结合，并与另一种称为DCAF 1的蛋白结合。DCAF 1/DDB 1是细胞的分子机器，可以破坏不需要的蛋白质。我们的研究结果表明，Vpr导致DDB 1降解某些细胞蛋白，我们假设其中至少有一种是病毒需要破坏以复制的抗病毒蛋白。该项目将确定DDB 1的目标，并了解这些蛋白质如何对抗病毒。此外，Vpr似乎会影响DCAF 1/DDB 1复合物的正常功能，从而破坏细胞中的功能，如DNA修复和DNA复制。该项目将确定这是如何发生的，以及它如何影响艾滋病毒的复制。

DESCRIPTION (provided by applicant): HIV-1 Vpr is a nuclear, virion packaged accessory protein encoded by all lentiviruses. SIV/HIV-2 encodes in addition, Vpx which maintains close sequence similarity. The hallmark of Vpr is that it induces G2/M cell cycle arrest. A key to understanding the role of Vpr/Vpx in virus replication and pathogenesis is the identification of the cellular proteins with which they interact. Several groups, including ours, recently reported the identification of a cellular complex with which Vpr and perhaps Vpx interact and through which they may function. The complex is an E3 ubiquitin ligase that consists of DDB1/DCAF1/CUL4A/ROC1. This complex regulates genomic DNA replication and damaged DNA repair by mediating the destruction of cellular proteins including the DNA replication-licensing factor CDT1, STAT1 and STAT2 and other, yet to be identified substrates. The identification of the interaction with the E3 ubiquitin ligase presents a unified explanation of how Vpr may mediate its effects and provides a framework to elucidate the role that Vpr plays in HIV-1 pathogenesis. Other viruses encode proteins that target this complex, using it as a means to induce degradation of STAT proteins to inhibit type-I interferon responses. We will determine whether Vpr acts through its interaction with the complex to arrest cells in G2, induce apoptosis and activate DNA damage signaling pathways. In addition, cellular proteins that bind to Vpx and to DCAF1 will be identified and characterized. Thirdly, the project will test they hypothesis that Vpr/Vpx play a role in dampening innate immune responses to the virus. Innate immunity has over the past several years become a topic of great interest. The project will determine whether Vpr/Vpx may constitute another such mechanism. PUBLIC HEALTH RELEVANCE Cells have mechanism by which they resist infection by viruses. These mechanism are of great interest because they provide new avenues for the development of antiviral drugs. Viruses have evolved means of escaping these so called innate immune mechanisms. HIV, for example produces a protein called virion infectivity factor( VIF) that inactivates one of the antiviral proteins that are produced by blood cells. In this project we will study an HIV protein called viral protein R (VPR) that may serve as yet another means by which the virus avoids the innate immune mechanisms. When a cell is infected with HIV, Vpr is produced and as we recently discovered, binds to a cellular protein called damaged DNA binding protein 1 (DDB1) in association with another protein called DCAF1. DCAF1/DDB1 is a molecular machine of the cell that destroys unwanted proteins. Our findings have shown that Vpr causes DDB1 to degrade certain cellular proteins and we hypothesize that at least one of these is an antiviral protein that the virus needs to destroy in order to replicate. The project will identify the targets of DDB1 and understand how these proteins work against the virus. In addition, Vpr seems to affect the normal function of the DCAF1/DDB1 complex and thereby disrupt functions in the cell such as DNA repair and DNA replication. The project will determine how this happens and how it affects replication of HIV.