cGAS enhances the HTLV-1 reverse transcription intermediate ssDNA90-induced innate immune re-sponses / 中华微生物学和免疫学杂志

ABSTRACT

Objective To 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 transfect-ed into these cells 24 hours later. Real-time PCR was used to measure the expression of IFN-β,IP-10,RAN-TES and TNF-α. Immunoblot assay was performed to measure phosphorylated IRF3 and p65. Results Ex-pression 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 en-hanced 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,RAN-TES and TNF-α after ssDNA90 transfection. Moreover,ssDNA90-induced phosphorylation of IRF3 and p65 were decreased after cGAS gene-knockdown. Conclusion cGAS might promote HTLV-1 RTI ssDNA90-in-duced innate immune responses.