Separate Cellular Localizations of Human T-Lymphotropic Virus 1 (HTLV-1) Env and Glucose Transporter Type 1 (GLUT1) Are Required for HTLV-1 Env-Mediated Fusion and Infection
Separate Cellular Localizations of Human T-Lymphotropic Virus 1 (HTLV-1) Env and Glucose Transporter Type 1 (GLUT1) Are Required for HTLV-1 Env-Mediated Fusion and Infection
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DOI：
10.1128/jvi.02686-14
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发表时间：
2015-01-01
影响因子：
5.4
通讯作者：
Harada, Shinji
中科院分区：
文献类型：
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作者：
Maeda, Yosuke;Terasawa, Hiromi;Harada, Shinji
人嗜T淋巴细胞病毒1型（HTLV-1）的包膜糖蛋白（Env）与靶细胞中表达的葡萄糖转运蛋白1（GLUT1）的相互作用是病毒进入细胞所必需的。本研究发现，GLUT1在产病毒293T细胞中的表达水平与HTLV-1 Env介导的融合活性和感染性呈负相关。GLUT 1和GLUT 3的嵌合研究表明，GLUT 1的胞外环6（ECL 6）对于抑制Env介导的细胞-细胞融合是重要的。当通过巴弗洛霉素A1（BFLA1）处理293T细胞中的GLUT1从细胞内储存位点易位到质膜中时，HTLV-1 Env介导的细胞融合和感染也被抑制而没有GLUT1的过表达，这表明GLUT1在细胞内区室而不是在质膜中的定位对于HTLV-1 Env的融合活性至关重要。免疫沉淀和激光扫描共聚焦显微镜分析表明，在正常条件下，HTLV-1 Env和GLUT 1不共定位或相互作用。BFLA1治疗诱导这种共定位和相互作用，表明GLUT1通常积累在细胞内隔室分离的Env。FLAG标记的HTLV-1 Env在病毒产生细胞中的蛋白质印迹分析和HTLV-1 Env在病毒样颗粒（VLP）中的掺入表明，Env的加工在病毒产生293T细胞中被过表达GLUT 1或BFLA1处理抑制。这种抑制可能是由于Env与细胞内隔室中的GLUT 1相互作用。两者合计，单独的细胞内定位GLUT 1和HTLV-1 Env所需的融合活性和感染性的HTLV-I Env。重要信息δ逆转录病毒HTLV-1是成人T细胞白血病（ATL）和HTLV-1相关的脊髓病/热带痉挛性下肢轻瘫（HAM/TSP）的病原体。虽然HTLV-1是一种具有辅助基因的复杂逆转录病毒，但尚未显示HTLV-1基因产物在病毒产生细胞中调节其受体GLUT 1。在这项研究中，我们发现大量的GLUT I或GLUT 1从病毒产生细胞的细胞内区室易位到质膜，增强了GLUT I与HTLV-1 Env的共定位和相互作用，导致细胞融合活性和感染性的抑制。我们的研究结果表明，GLUT 1通常积累在与Env分开的细胞内区室中，这确实是正确处理Env所需要的。
Interaction of the envelope glycoprotein (Env) of human T-lymphotropic virus 1 (HTLV-1) with the glucose transporter type 1 (GLUT1) expressed in target cells is essential for viral entry. This study found that the expression level of GLUT1 in virus-producing 293T cells was inversely correlated with HTLV-1 Env-mediated fusion activity and infectivity. Chimeric studies between GLUT1 and GLUT3 indicated that the extracellular loop 6 (ECL6) of GLUT1 is important for the inhibition of cell-cell fusion mediated by Env. When GLUT1 was translocated into the plasma membrane from intracellular storage sites by bafilomycin A1 (BFLA1) treatment in 293T cells, HTLV-1 Env-mediated cell fusion and infection also were inhibited without the overexpression of GLUT1, indicating that the localization of GLUT1 in intracellular compartments rather than in the plasma membrane is crucial for the fusion activity of HTLV-1 Env. Immunoprecipitation and laser scanning confocal microscopic analyses indicated that under normal conditions, HTLV-1 Env and GLUT1 do not colocalize or interact. BFLA1 treatment induced this colocalization and interaction, indicating that GLUT1 normally accumulates in intracellular compartments separate from that of Env. Western blot analyses of FLAG-tagged HTLV-1 Env in virus-producing cells and the incorporation of HTLV-1 Env in virus-like particles (VLPs) indicate that the processing of Env is inhibited by either overexpression of GLUT1 or BFLA1 treatment in virus-producing 293T cells. This inhibition probably is due to the interaction of the Env with GLUT1 in intracellular compartments. Taken together, separate intracellular localizations of GLUT1 and HTLV-1 Env are required for the fusion activity and infectivity of HTLV-I Env.IMPORTANCEThe deltaretrovirus HTLV-1 is a causative agent of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Although HTLV-1 is a complex retrovirus that has accessory genes, no HTLV-1 gene product has yet been shown to regulate its receptor GLUT1 in virus-producing cells. In this study, we found that a large amount of GLUT I or translocation of GLUT1 to the plasma membrane from intracellular compartments in virus-producing cells enhances the colocalization and interaction of GLUT I with HTLV-1 Env, leading to the inhibition of cell fusion activity and infectivity The results of our study suggest that GLUT1 normally accumulates in separate intracellular compartments from Env, which is indeed required for the proper processing of Env.