人类T淋巴细胞白血病病毒1型(HTLV-1)Tax蛋白对HLA-G表达的影响

Effects of HTLV-1 protein Tax on HLA-G expression

目的:研究人类白细胞抗原G(HLA-G)在人类T淋巴细胞白血病病毒1型(HTLV-1)感染中的表达情况,探讨HLA-G在HTLV-1逃逸宿主免疫应答中的功能和机制。方法:采用HTLV-1稳定感染的细胞系MT2分别感染HeLa和THP-1细胞,qRT-PCR和Western blot检测HLA-G异构体在mRNA和蛋白质水平的表达情况,流式细胞术检测HLA-G1的表达情况。在HeLa细胞中通过转染上调HLA-G的表达以及采用siRNA基因沉默HLA-G,再用HTLV-1感染细胞,从蛋白质水平上验证HTLV-1特征性病毒蛋白Tax的改变。结果:HTLV-1感染HeLa和THP-1细胞能诱导HLA-G异构体的差异性表达,以HLA-G1、HLA-G5为主;HTLV-1病毒感染宿主细胞24 h后HLA-G mRNA和蛋白质水平表达明显上调。同时,过表达HLA-G的HeLa细胞被HTLV-1病毒感染后病毒蛋白Tax明显升高,采用siRNA的手段将HeLa细胞HLA-G基因沉默后,则得到相反的结果。结论:免疫耐受分子HLA-G在HTLV-1感染细胞后表达量明显上升,从而促进HTLV-1病毒蛋白的传播和复制,进而导致病毒的持续感染。

Objective To study the expression of human leukocyte antigen G(HLA-G)during human T lymphocytic leukemia virus type 1(HTLV-1)infection,and to investigate the function and mechanism of HLA-G in HTLV-1 immune escape.Methods HeLa and THP-1 cells were infected by MT2,a stable HTLV-1 infected cell line.Expression of HLA-G isomers at mRNA and protein levels was detected by qRT-PCR and Western blot,respectively.Flow cytometry was used to detect the expression of HLA-G1.Moreover,transfection and siRNA gene were respectively used to up-regulate and silence HLA-G expression in HeLa cells to observe the changes in the expression of HTLV-1-featured protein Tax on protein level after HTLV-1 infection.Results HTLV-1 infection could induce differential expression of HLA-G isomers,mainly HLA-G1 and HLA-G5,in HeLa and THP-1 cells.HLA-G expression at both mRNA and protein levels was significantly up-regulated 24 h after HTLV-1 infection.Moreover,the expression of HTLV-1 protein Tax was significantly enhanced in HTLV-1-infected HeLa cells overexpressing HLA-G.An opposite result was obtained when the HLA-G gene in HeLa cells was silenced by siRNA.Conclusions The immune-tolerant molecule HLA-G was significantly increased in HTLV-1-infected cells,thereby promoting the expression of HTLV-1 viral protein,which led to persistent viral infection.