cGAS通过调控固有免疫应答抑制HTLV-1在HeLa细胞中复制

摘要

目的 探讨DNA识别受体环鸟苷酸-腺苷酸合成酶(cGAS)在成人T淋巴细胞白血病病毒1型(HTLV-1)感染HeLa细胞过程中的功能及其作用机制.方法 将HeLa细胞与MT2细胞(HTLV-1阳性T细胞)共培养,采用免疫印迹试验检测cGAS在HeLa细胞中的表达变化;构建带有血凝素(HA)标签的cGAS表达质粒,转染入HeLa细胞24 h后与MT2细胞共培养24 h,免疫印迹试验检测HeLa细胞中HTLV-1病毒蛋白Tax和p19的表达量,real-time PCR检测HeLa细胞中HTLV-1病毒基因Tax、p19、Env、HBZ以及px转录本的量,同时免疫印迹试验检测干扰素调节因子3(IRF3)和p65的磷酸化水平,real-time PCR检测干扰素(IFN)-β、干扰素诱导蛋白10(IP-10)、调节活化正常T细胞表达和趋化因子(RANTES)和肿瘤坏死因子(TNF)-α的表达量.结果 与MT2细胞共培养后,HeLa细胞中cGAS的表达升高;转染有cGAS表达质粒的HeLa细胞与对照组细胞相比,在与MT2细胞共培养后,Tax和p19在蛋白水平上的表达量减少,Tax、p19、EnV、HBZ以及px转录本的量减少,IRF3和p65的磷酸化水平升高,IFN-β、IP-10、RANTES和TNF-α的表达量增加.结论 cGAS在HTLV-1感染的HeLa细胞中可能具有促进固有免疫应答并抑制HTLV-1病毒复制的功能.%Objective To investigate the function and the possible mechanism of cyclic GMP-AMP synthase (cGAS), a DNA sensor, in HeLa cells during human T cell leukemia virus type 1 (HTLV-1) in-fection.Methods HeLa cells were co-cultured with MT2 cells (HTLV-1-positive T cells) and then detec-ted by immunoblot assay to analyze the changes in the expression of cGAS .A hemagglutinin ( HA)-tagged cGAS plasmid was constructed and transfected into HeLa cells .Twenty-four hours after transfection , these cells were co-cultured with MT2 cells for another 24 hours.Immunoblot assay was used to detect the expres-sion of HTLV-1 proteins Tax and p19.Real-time PCR was performed to measure the expression of HTLV-1 Tax, p19, Env, HBZ and px at mRNA level .Immunoblot assay was also used to analyze the phosphorylation of interferon regulatory factor 3 (IRF3) and p65.Expression of interferon (IFN)-β, IFN-gamma-inducible protein 10 ( IP-10 ) , RANTES ( regulated on activation , normal T cell expressed and secreted ) and tumor necrosis factor (TNF)-αwas detected by real-time PCR assay.Results Expression of cGAS was enhanced in HeLa cells after co-cultured with MT2 cells.Compared with control cells , the HeLa cells that were trans-fected with cGAS plasmid showed lower levels of Tax and p 19 proteins, suppressed expression of HTLV-1 Tax, p19, Env, HBZ and px at mRNA level , enhanced phosphorylation of IRF 3 and p65, and higher levels of IFN-β, IP-10, RANTES and TNF-αafter co-cultured with MT2 cells.Conclusion cGAS might promote the innate immune response and inhibit HTLV-1 replication in HTLV-1-infected HeLa cells .