Molecular Analysis Of Retroviral Genes And Their Pr

逆转录病毒基因及其表达的分子分析

• 批准号: 7301900
• 负责人: KLAUS STREBEL
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7301900
• 关键词: Molecular; Analysis; Retroviral; Genes; Their

HIV-1 encodes a number of genes that are crucial for replication in primate cells. Gag, Pol, and Env products represent the main virion components, while Tat and Rev products regulate intracellular transcriptional and post-transcriptional events for the controlled expression of viral genes. Of particular interest are the HIV accessory proteins Vif, Vpr, Vpu, Vpx, and Nef, which are unique to primate lentiviruses. There is increasing evidence that these proteins operate in conjunction with specific host factors. In fact, most if not all, of the accessory proteins appear to lack catalytic activities but instead seem to function as adaptors to link viral or cellular factors to pre-existing cellular pathways. In FY 2006, we conducted studies to improve our understanding of the biochemical properties of a recently identified Vif-sensitive host factor, APOBEC3G. We demonstrated earlier that inhibition of HIV-1 by APOBEC3G requires its packaging into HIV-1 virions through association with the viral RNA. Several studies found that APOBEC3G can be packaged into virus-like particles in an RNA-independent manner; however, our own data demonstrate that such RNA-independent packaging of APOBEC3G will not cause an antiviral effect. Thus, APOBEC3G not only has to be present in virions but, more specifically, must be associated with the viral core to exert antiviral activity. More recently, we determined that APOBEC3G is packaged into virions in monomeric form. This study is significant since intracellularly APOBEC3G efficiently multimerizes and forms large RNA-dependent multi-protein complexes. The functional significance of such APOBEC3G complexes remains to be determined; however, our data suggest that they most likely do not have functional significance for either encapsidation into HIV-1 virions or anti-viral activity. The HIV accessory protein Vif has the remarkable ability to inhibit the antiviral activity of APOBEC3G. We found that Vif can cause efficient depletion of APOBEC3G from virus-producing cells; however, we also found that such depletion could be functionally dissociated from the antiviral effect of APOBEC3G. We identified Vif variants that efficiently reduced cellular APOBEC3G without restoring viral infectivity and vice versa. We also identified APOBEC3G variants that were insensitive to Vif-induced degradation but whose antiviral activity remained Vif-sensitive. These studies are highly significant since they demonstrate that Vif does not merely act as an adaptor molecule to trigger the degradation of APOBEC3G but has additional yet undefined functions required to control the antiviral effect of APOBEC3G.

HIV-1编码许多对于灵长类动物细胞复制至关重要的基因。 GAG，POL和ENV产品代表主要的病毒粒子成分，而TAT和REV产品调节细胞内转录和转录后事件，以控制病毒基因的控制表达。特别有趣的是HIV附件VIF，VPR，VPU，VPX和NEF，这是灵长类动病毒所独有的。越来越多的证据表明这些蛋白质与特定宿主因素结合起作用。实际上，大多数辅助蛋白似乎缺乏催化活性，但似乎是将病毒或细胞因子与预先存在的细胞途径联系起来的适配器。在2006财年，我们进行了研究，以提高我们对最近确定的VIF敏感宿主因子Apobec3g的生化特性的理解。我们早些时候证明，APOBEC3G对HIV-1的抑制需要通过与病毒RNA结合将其包装到HIV-1病毒中。几项研究发现，Apobec3g可以以RNA独立的方式包装到病毒样颗粒中。但是，我们自己的数据表明，这种无RNA无关的apobec3g包装不会引起抗病毒作用。因此，apobec3g不仅必须存在于病毒体中，而且更具体地，必须与病毒核有关以发挥抗病毒活性。最近，我们确定以单体形式将APOBEC3G包装到病毒体中。这项研究很重要，因为细胞内apobec3g有效地将大量的RNA依赖性多蛋白质复合物形成。这种ApoBec3G复合物的功能意义尚待确定；但是，我们的数据表明，它们很可能对封装在HIV-1病毒体或抗病毒活性中没有功能意义。 HIV辅助蛋白VIF具有抑制APOBEC3G抗病毒活性的显着能力。我们发现VIF会导致产生病毒细胞的Apobec3g有效耗竭。但是，我们还发现，这种耗竭可以在功能上与apobec3g的抗病毒作用分离。我们确定了有效降低细胞apobec3g而不恢复病毒感染性的VIF变体，反之亦然。我们还鉴定出对VIF诱导的降解不敏感但其抗病毒活性仍然对VIF敏感的变体。这些研究非常重要，因为它们表明VIF不仅是触发APOBEC3G降解的衔接子分子，而且还具有控制Apobec3g的抗病毒效应所需的额外但不确定的功能。