BioProject

The DNA sensor cGAS senses cytosolic DNA and catalyzes the production of the cyclicdinucleotide cGAMP, resulting in type I IFN responses. More...

The DNA sensor cGAS senses cytosolic DNA and catalyzes the production of the cyclicdinucleotide cGAMP, resulting in type I IFN responses. We addressed the functionality of cGAS-mediated DNA sensing in human and murine T-cells. Activated primary CD4+ T-cells expressed cGAS and responded robustly to plasmid DNA by upregulation of ISGs and release of bioactive interferon. In mouse T-cells, cGAS KO ablated sensing of plasmid DNA, and TREX1 KO enabled cells to sense short immunostimulatory DNA. Basal expression of IFIT1 and MX2 was downregulated and upregulated in cGAS KO and TREX1 KO T-cell lines, respectively, compared to parental cells. Despite their intact cGAS sensing pathway, human CD4+ T-cells failed to mount a reverse transcriptase (RT) inhibitor-sensitive immune response following HIV-1 infection. In contrast, infection of human T-cells with HSV-1 that is functionally deficient for the cGAS antagonist pUL41 (HSV-1ΔUL41N) resulted in a cGAS dependent type I IFN response. In accordance with our results in primary CD4+ T-cells, plasmid challenge or HSV-1ΔUL41N inoculation of representative T-cell lines provoked an entirely cGAS-dependent type I IFN response, including IRF3 phosphorylation and expression of ISGs. In contrast, no RT-dependent type I IFN response was detected following transduction of T cell lines with VSV-G-pseudotyped lentiviral or gammaretroviral particles. Together, T-cells are capable to raise a cGAS-dependent cell-intrinsic response to both plasmid DNA challenge or inoculation with HSV-1ΔUL41N. However, HIV-1 infection does not appear to trigger cGAS-mediated sensing of viral DNA in T-cells, possibly by revealing viral DNA of insufficient quantity, length, and/or accessibility to cGAS. Overall design: Human CD4+ T cells of four healthy human donors were purified from whole blood samples by negative selection. Plated cells were inoculated with HIV-1Ba-L or control supernatant and subsequently treated with EFV. Total RNA from CD4+ T cells was extracted after the 3, 8, 48, 144, or 312 h post inoculation and RNAseq was performed. Less...