Nef-Host Interactions in Virus Replication

描述（由申请方提供）：Nef是一种辅助病毒基因产物，在猴模型中已显示其为高滴度病毒复制和AIDS发病机制所需。此外，感染HIV-1的nef缺陷株与人类疾病进展的缺乏有关。虽然Nef似乎对体内有效的病毒复制至关重要，但其作用机制尚不清楚。在细胞培养中，Nef可显示下调来自细胞表面的CD 4和MHC I类，以调节细胞活化状态，并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广泛表达的GT3发动蛋白2相互作用，GT3发动蛋白2对于网格蛋白介导的内吞作用是必不可少的，并介导内吞囊泡出芽过程中的分裂步骤。我们的研究结果还意味着，这种相互作用是至关重要的增强病毒感染性的Nef，因为我们发现，这种功能可以特异性抑制显性负动力蛋白2，但不是动力蛋白1。由于发动蛋白2参与内吞作用，我们的研究结果进一步表明，下调一个尚未确定的因素从细胞表面Nef可能需要最佳的HIV-1感染性。我们的目标是阐明是什么使Nef与发动蛋白2相互作用，但不与密切相关的亚型，了解HIV-1感染性和复制的相互作用的相关性，并确定Nef和发动蛋白2的下游目标。了解发动蛋白2在Nef感染性增强中的作用可能最终为抗病毒治疗提供有希望的新靶点，特别是因为发动蛋白2的已知功能表明细胞表面蛋白的参与。

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.