HIV nef-mediated CD4 down-regulation is adaptor protein complex 2 dependent
HIV nef-mediated CD4 down-regulation is adaptor protein complex 2 dependent
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DOI：
10.4049/jimmunol.175.5.3157
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发表时间：
2005-09-01
影响因子：
4.4
通讯作者：
Burakoff, SJ
中科院分区：
文献类型：
--
作者：
Jin, YJ;Cai, CY;Burakoff, SJ
Nef 是艾滋病毒高滴度复制和艾滋病发病的关键病毒蛋白。Nef 的一个功能是下调细胞表面的 CD4，这与 Nef 增强病毒致病性有关。Nef 通过将 CD4 与凝集素包被的坑相连来下调 CD4。然而，Nef 的 C 端二亮氨酸基团与凝集素包被坑的成分之间的机理联系尚未明确。在本报告中，我们使用了两种 AP-2 复合物特异性抑制剂：一种是与 AP-2 复合物α亚基结合的 Eps15 显性负突变体（Eps15DIII），另一种是针对 AP-2 复合物μ2 亚基的特异性小干扰 RNA。我们发现，在 Eps15DIII 和 RNA 干扰 AP-2 表达的协同作用下，HIV Nef 和 SIV Nef 介导的 CD4 下调均被显著阻断。结果表明，HIV/SIV Nef 介导的 CD4 下调依赖于 AP-2。我们还发现，PMA 诱导的 CD4 下调被这两种抑制剂阻断。因此，PMA 诱导的 CD4 下调也依赖于 AP-2。这些结果表明，与酪氨酸分选基调依赖性内吞（转铁蛋白受体和表皮生长因子受体是其两个原型）一样，Nef 和 CD4 的二亮氨酸分选基调依赖性内吞也是 AP-2 依赖性的。
Nef is a crucial viral protein for HIV to replicate at high titers and in the development of AIDS. One Nef function is down-regulating CD4 from the cell surface, which correlates with Nef-enhanced viral pathogenicity. Nef down-regulates CD4 by linking CD4 to clathrin-coated pits. However, the mechanistic connection between the C-terminal dileucine motif of Nef and the component(s) of the clathrin-coated pits has not been pinpointed. In this report we used two AP-2 complex-specific inhibitors: a dominant negative mutant of Eps15 (Eps15DIII) that binds to the alpha subunit of AP-2 complex and a small interference RNA that is specific for the mu 2 subunit of AP-2 complex. We show that both HIV Nef- and SIV Nef-mediated CD4 down-regulations were profoundly blocked by the synergistic effect of Eps15DIII and RNA interference of AP-2 expression. The results demonstrate that HIV/SIV Nef-mediated CD4 down-regulation is AP-2 dependent. We also show that the PMA-induced CD4 down-regulation was blocked by these two inhibitors. Therefore, PMA-induced CD4 down-regulation is also AP-2 dependent. The results demonstrate that, like the tyrosine sorting motif-dependent endocytosis (for which the transferrin receptor and the epidermal growth factor receptor are the two prototypes), dileucine sorting motif-dependent endocytosis of Nef and CD4 are also AP-2 dependent.