Fu Enqing, Pan Lei, Xie Yonghong, Mu Deguang, Liu Wei, Jin Faguang, Bai Xuefan
Department of Respiratory and Critical Medicine, Tangdu Hospital, Fourth Military Medical University Xi'an, China.
Department of Infectious Diseases, Tangdu Hospital, Fourth Military Medical University Xi'an, China.
Int J Clin Exp Pathol. 2015 Feb 1;8(2):1184-98. eCollection 2015.
Macrophages and CD4(+) T-cells are the major reservoirs for HIV-1 infection. CD63 is a tetraspanin transmembrane protein, which has been shown to play an essential role during HIV-1 replication in macrophages. In this study, we further confirm the requirement of CD63 in HIV-1 replication events in primary human CD4(+) T-cells, dendritic cells, and a CD4(+) cell line. Most interestingly, we also show the evidences for the co-localization and internalization of CD63 and HIV-1 major receptor CD4 in primary human macrophages and CD4(+) cell line by confocal microscopy and Co-Immunoprecipitation assay. Analysis revealed that CD63-depleted CD4(+) T-cells, dendritic cells, and a cell line showed significant decrease in HIV-1 production. Further analysis showed that CD63 down regulation reduced production of the early HIV protein Tat, and affected HIV protein Gag by CD63-Gag interaction. In agreement, CD63 silencing also inhibited production of the late protein p24. Furthermore, we revealed that CD63 silencing has no effect on HIV-1 replication with extensive viral challenge (MOI > 0.2). These findings suggest that CD63 plays a dual-role both in early and late HIV-1 life cycle with a range of HIV-1 infection (MOI < 0.2).
巨噬细胞和CD4(+) T细胞是HIV-1感染的主要储存库。CD63是一种四跨膜蛋白，已证明其在巨噬细胞中HIV-1复制过程中发挥重要作用。在本研究中，我们进一步证实了CD63在原代人CD4(+) T细胞、树突状细胞和一种CD4(+)细胞系的HIV-1复制事件中的必要性。最有趣的是，我们还通过共聚焦显微镜和免疫共沉淀试验展示了在原代人巨噬细胞和CD4(+)细胞系中CD63与HIV-1主要受体CD4共定位和内化的证据。分析显示，CD63缺失的CD4(+) T细胞、树突状细胞和一种细胞系的HIV-1产生显著减少。进一步分析表明，CD63下调降低了早期HIV蛋白Tat的产生，并通过CD63-Gag相互作用影响HIV蛋白Gag。同样，CD63沉默也抑制了晚期蛋白p24的产生。此外，我们发现，在广泛的病毒攻击（MOI>0.2）下，CD63沉默对HIV-1复制没有影响。这些发现表明，在一系列HIV-1感染（MOI<0.）中，CD63在HIV-1生命周期的早期和晚期均发挥双重作用。
