Nef-Host Interactions in Virus Replication

描述（由申请人提供）：Nef是一种辅助病毒基因产物，在猴子模型中已被证明是高滴度病毒复制和艾滋病发病所必需的。此外，感染HIV-1的新缺陷毒株与人类没有疾病进展有关。虽然Nef似乎对病毒在体内的有效复制至关重要，但其作用机制尚不清楚。在细胞培养中，Nef可从细胞表面下调CD4和MHC I类，调节细胞活化状态，直接增强子代病毒粒子的感染性。我们的初步结果现在确定HIV-1 Nef以高度特异性的方式与普遍表达的GTPase动力蛋白2相互作用，GTPase动力蛋白2对于网格蛋白介导的内吞作用至关重要，并在内吞囊泡出芽期间介导裂变步骤。我们的研究结果还表明，这种相互作用对Nef增强病毒传染性至关重要，因为我们发现这种功能可以被显性负动力蛋白2特异性抑制，而不是动力蛋白1。由于动力蛋白2参与内吞作用，我们的研究结果进一步表明，Nef从细胞表面下调一种尚未确定的因子可能是优化HIV-1感染所必需的。我们的目标是阐明是什么使Nef与动力蛋白2相互作用，而不是与密切相关的异构体相互作用，了解相互作用与HIV-1感染和复制的相关性，并确定Nef和动力蛋白2的下游靶点。对动力蛋白2在Nef感染增强中的作用的理解可能最终为抗病毒治疗提供有希望的新靶点，特别是因为已知的动力蛋白2的功能表明参与了细胞表面蛋白。

DESCRIPTION (provided by applicant): Nef is an accessory viral gene product that has been shown to be required for high titer virus replication and AIDS pathogenesis in a monkey model. Furthermore, infection with nef-defective strains of HIV-1 has been associated with the absence of disease progression in humans. While Nef appears crucial for efficient virus replication in vivo, the mechanism by which it acts is poorly understood. In cell culture, Nef can be shown to down-regulate CD4 and MHC class I from the cell surface, to modulate the cellular activation state, and to directly enhance the infectivity of progeny virions. Our preliminary results now establish that HIV-1 Nef interacts in a highly specific manner with the ubiquitously expressed GTPase dynamin 2, which is essential for clathrin-mediated endocytosis and mediates the fission step during endocytic vesicle budding. Our results also imply that this interaction is crucial for the enhancement of viral infectivity by Nef, since we find that this function can be specifically inhibited by dominant-negative dynamin 2 but not dynamin 1. Because of the involvement of dynamin 2 in endocytosis, our results further suggest that the down-regulation of an as yet unidentified factor from the cell surface by Nef may be required for optimal HIV-1 infectivity. Our goals are to elucidate what enables Nef to interact with dynamin 2 but not with closely related isoforms, to understand the relevance of the interaction for HIV-1 infectivity and replication, and to identify the downstream target of Nef and dynamin 2. An understanding of the role of dynamin 2 in the infectivity enhancement of Nef may ultimately provide promising new targets for anti-viral therapy, particularly since the known function of dynamin 2 suggests the involvement of a cell surface protein.