cGAS促进HTLV-1反转中间体ssDNA90诱导的固有免疫应答

cGAS enhances the HTLV-1 reverse transcription intermediate ssDNA90-induced innate immune responses

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）的反转中间体诱导的固有免疫信号通路中的调控功能。方法将HTLV-1的反转中间体ssDNA90转染入HeLa细胞，采用免疫印迹试验检测cGAS在HeLa细胞中的表达变化；将cGAS表达质粒，转染入HeLa细胞，24 h后再转染入ssDNA90，real-time PCR试验检测HeLa细胞中干扰素（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，免疫印迹试验检测HeLa细胞中干扰素调节因子3（IRF3）和p65的磷酸化水平；采用siRNA的方法在HeLa和佛波酯（phorbol-12-myristate-13-acetate，PMA）诱导分化的THP1（PMA-THP1）细胞中沉默cGAS的表达，24 h后再转染入ssDNA90，real-time PCR试验检测HeLa和PMA-THP1细胞中IFN-β、IP-10、RANTES和TNF-α的表达，免疫印迹试验检测HeLa和PMA-THP1细胞中IRF3和p65的磷酸化水平。结果ssDNA90转染后，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ssDNA90刺激后，IFN-β、IP-10、RANTES和TNF-α的表达量增加，IRF3和p65的磷酸化水平升高；沉默cGAS表达的HeLa和PMA-THP1细胞与对照组细胞相比，在ssDNA90刺激后，IFN-β、IP-10、RANTES和TNF-α的表达量降低，IRF3和p65的磷酸化水平下降。结论cGAS在HTLV-1的反转中间体ssDNA90诱导的固有免疫应答中可能具有促进功能。

ObjectiveTo investigate the role of cyclic GMP-AMP synthase （cGAS）, a cytosolic DNA sensor, in regulating innate immune responses induced by reverse transcription intermediate of human T cell leukemia virus type 1 （HTLV-1）.Methods（1）ssDNA90, the reverse transcription intermediate of HTLV-1, was transfected into HeLa cells to observe changes in the expression pattern of cGAS in transfected-HeLa cells with immunoblot assay.（2）HeLa cells were firstly transfected with cGAS-encoding plasmid and then ssDNA90 24 hours later.Real-time PCR was used to measure the expression of interferon （IFN）-β, IFN-gamma-inducible protein 10 （IP-10）, regulated on activation, normal T cell expressed and secreted （RANTES） and tumor necrosis factor （TNF）-α.Immunoblot assay was performed to measure phosphorylated interferon regulatory factor 3 （IRF3） and p65.（3）cGAS expression was silenced by siRNA in HeLa and phorbol-12-myristate-13-acetate （PMA）-treated THP1 （PMA-THP1） cells and then ssDNA90 was transfected into these cells 24 hours later.Real-time PCR was used to measure the expression of IFN-β, IP-10, RANTES and TNF-α.Immunoblot assay was performed to measure phosphorylated IRF3 and p65.ResultsExpression of cGAS was increased in HeLa cells after ssDNA90 transfection.Compared with control cells, cGAS-transfected HeLa cells showed increased expression of IFN-β, IP-10, RANTES and TNF-α and enhanced phosphorylation of IRF3 and p65 after ssDNA90 transfection.Compared with control cells, both HeLa and PMA-THP1 cells with silenced expression of cGAS showed impaired production of IFN-β, IP-10, RANTES and TNF-α after ssDNA90 transfection.Moreover, ssDNA90-induced phosphorylation of IRF3 and p65 were decreased after cGAS gene-knockdown.ConclusioncGAS might promote HTLV-1 RTI ssDNA90-induced innate immune responses.