Role of Abl Kinase and the Wave2 Signaling Complex in HIV-1 Entry at a Post-Hemifusion Step
Role of Abl Kinase and the Wave2 Signaling Complex in HIV-1 Entry at a Post-Hemifusion Step
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DOI：
10.1371/journal.ppat.1000956
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发表时间：
2010-06-01
期刊：
影响因子：
6.7
通讯作者：
Ratner, Lee
中科院分区：
文献类型：
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作者：
Harmon, Brooke;Campbell, Nancy;Ratner, Lee
人类免疫缺陷病毒1型（HIV-1）的进入始于包膜糖蛋白（Env）与受体CD4和两种辅助受体CXCR4或CCR5之一的结合。通过协同受体介导的env信号导致G α q介导的Rac激活和融合所必需的肌动蛋白细胞骨架重排。鸟嘌呤核苷酸交换因子（GEFs）激活Rac并调节其下游蛋白效应物。在这项研究中，我们发现env诱导的Rac激活是由Rac GEF Tiam-1介导的，它与适配器蛋白IRSp53结合，将Rac连接到Wave2复合体。Rac和酪氨酸激酶Abl随后激活Wave2复合物并促进arp2 /3依赖性肌动蛋白聚合。env介导的细胞-细胞融合、病毒-细胞融合和HIV-1感染依赖于Tiam-1、Abl、IRSp53、Wave2和Arp3，这一点可以通过表达靶向这些信号成分的siRNA的细胞的融合和感染衰减来证明。HIV-1环境依赖性细胞-细胞融合、病毒-细胞融合和感染也被Abl激酶抑制剂、伊马替尼、尼洛替尼和达沙替尼抑制。用Abl激酶抑制剂处理细胞不影响细胞活力或CD4和CCR5的表面表达。当检测env依赖性细胞-细胞融合、病毒-细胞融合或感染，以及以细胞系或原代细胞为目标时，使用抑制剂和sirna获得了类似的结果。利用膜弯曲剂和荧光显微镜，我们发现Abl激酶活性的抑制阻止了半融合（脂质混合）步骤的融合，这表明Abl介导的肌动蛋白重塑在孔隙形成和扩张中的作用。这些结果提示Abl激酶抑制剂治疗HIV-1感染患者的潜在效用。
Entry of human immunodeficiency virus type 1 (HIV-1) commences with binding of the envelope glycoprotein (Env) to the receptor CD4, and one of two coreceptors, CXCR4 or CCR5. Env-mediated signaling through coreceptor results in G alpha q-mediated Rac activation and actin cytoskeleton rearrangements necessary for fusion. Guanine nucleotide exchange factors (GEFs) activate Rac and regulate its downstream protein effectors. In this study we show that Env-induced Rac activation is mediated by the Rac GEF Tiam-1, which associates with the adaptor protein IRSp53 to link Rac to the Wave2 complex. Rac and the tyrosine kinase Abl then activate the Wave2 complex and promote Arp2/3-dependent actin polymerization. Env-mediated cell-cell fusion, virus-cell fusion and HIV-1 infection are dependent on Tiam-1, Abl, IRSp53, Wave2, and Arp3 as shown by attenuation of fusion and infection in cells expressing siRNA targeted to these signaling components. HIV-1 Env-dependent cell-cell fusion, virus-cell fusion and infection were also inhibited by Abl kinase inhibitors, imatinib, nilotinib, and dasatinib. Treatment of cells with Abl kinase inhibitors did not affect cell viability or surface expression of CD4 and CCR5. Similar results with inhibitors and siRNAs were obtained when Env-dependent cell-cell fusion, virus-cell fusion or infection was measured, and when cell lines or primary cells were the target. Using membrane curving agents and fluorescence microscopy, we showed that inhibition of Abl kinase activity arrests fusion at the hemifusion (lipid mixing) step, suggesting a role for Abl-mediated actin remodeling in pore formation and expansion. These results suggest a potential utility of Abl kinase inhibitors to treat HIV-1 infected patients.