NONO detects the nuclear HIV capsid to promote cGAS-mediated innate immune activation
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE109554 | GEO | 2018/09/28
REPOSITORIES: GEO
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Project description:Upon recognition of aberrantly located DNA, the innate immune sensor cGAS activates STING/IRF-3-driven antiviral responses. Here we characterized the ability of a specific variant of the cGAS-encoding gene MB21D1, rs610913, to alter cGAS-mediated DNA sensing and viral infection. rs610913 is a frequent G>T polymorphism resulting in a P261H exchange in the cGAS protein. Data from the International Collaboration for the Genomics of HIV suggested that rs610913 nominally associates with HIV-1 acquisition in vivo. Molecular modeling of cGAS(P261H) hinted towards the possibility for an additional binding site for a potential cellular co-factor in cGAS dimers. However, cGAS(WT) or cGAS(P261H)-reconstituted THP-1 cGAS KO cells shared steady-state expression of interferon-stimulated genes (ISGs), as opposed to cells expressing the enzymatically inactive cGAS(G212A/S213A). Accordingly, cGAS(WT) and cGAS(P261H) cells were less susceptible to lentiviral transduction and infection with HIV-1, HSV-1, and Chikungunya virus as compared to cGAS KO- or cGAS(G212A/S213A) cells. Upon DNA challenge, innate immune activation appeared to be mildly reduced upon expression of cGAS(P261H) compared to cGAS(WT). Finally, DNA challenge of PBMCs from donors homozygously expressing rs610913 provoked a trend towards a slightly reduced type I IFN response as compared to PBMCs from GG donors. Taken together, the steady-state activity of cGAS maintains a base-line antiviral state rendering cells more refractory to ISG-sensitive viral infections. rs610913 failed to grossly differ phenotypically from the wild-type gene, suggesting that cGAS(P261H) and wild-type cGAS share a similar ability to sense viral infections in vivo.
2022-05-25 | GSE203334 | GEO
Project description:NONO detects the nuclear HIV capsid to promote cGAS-mediated innate immune activation
| PRJNA431379 | ENA
Project description:Eukaryotic cells recognize intracellular pathogens through pattern recognition receptors, including sensors of aberrant nucleic acid structures. Sensors of double-stranded RNA (dsRNA) are known to detect replication intermediates of RNA viruses. It has been suggested that annealing of mRNA from symmetrical transcription of both top and bottom strands of DNA virus genomes can produce dsRNA during infection. Supporting this hypothesis, nearly all DNA viruses encode inhibitors of dsRNA-recognition pathways. However, direct evidence that DNA viruses produce dsRNA is lacking. Contrary to dogma, we show that the nuclear-replicating DNA virus adenovirus (AdV) does not produce detectable levels of dsRNA during infection. In contrast, abundant dsRNA is detected within the nucleus of cells infected with AdV mutants that lack the virus-directed ubiquitin ligase required for efficient processing of viral RNA. In the presence of nuclear dsRNA, the cytoplasmic dsRNA sensor PKR is relocalized and activated within the nucleus. Accumulation of viral dsRNA occurs in the late phase of infection, when unspliced viral transcripts form intron/exon base pairs between top and bottom strand transcripts. We propose that DNA viruses actively promote efficient splicing and mRNA processing to limit dsRNA formation, thus avoiding detection and restriction by host nucleic acid sensors.
2021-07-15 | GSE179388 | GEO
Project description: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.
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Project description:Cytosolic DNA activates cyclic GMP-AMP (cGAMP) synthase (cGAS), an innate immune sensor pivotal in anti-microbial defense, senescence, auto-immunity and cancer. cGAS is considered a sequence-independent DNA sensor with limited access to nuclear DNA because of compartmentalization. However, the nuclear envelope is a dynamic barrier and cGAS is present in the nucleus. Here, we identify determinants of nuclear cGAS localization and activation. We show that nuclear-localized cGAS synthesizes cGAMP and induces innate immune activation of dendritic cells, but cGAMP levels are 200-fold lower than following transfection with exogenous DNA. Using cGAS ChIP-seq and a GFP-cGAS knock-in mouse, we find nuclear cGAS enrichment on centromeric satellite DNA, confirmed by imaging, and to a lesser extent with LINE elements. The non-enzymatic N-terminal domain of cGAS determines nucleo-cytoplasmic localization, enrichment on centromeres and activation of nuclear-localized cGAS. These results reveal a preferential functional association of nuclear cGAS with centromeres.
2019-02-27 | GSE125432 | GEO
Project description:Cytosolic DNA activates cyclic GMP-AMP (cGAMP) synthase (cGAS), an innate immune sensor pivotal in anti-microbial defense, senescence, auto-immunity and cancer. cGAS is considered a sequence-independent DNA sensor with limited access to nuclear DNA because of compartmentalization. However, the nuclear envelope is a dynamic barrier and cGAS is present in the nucleus. Here, we identify determinants of nuclear cGAS localization and activation. We show that nuclear-localized cGAS synthesizes cGAMP and induces innate immune activation of dendritic cells, but cGAMP levels are 200-fold lower than following transfection with exogenous DNA. Using cGAS ChIP-seq and a GFP-cGAS knock-in mouse, we find nuclear cGAS enrichment on centromeric satellite DNA, confirmed by imaging, and to a lesser extent with LINE elements. The non-enzymatic N-terminal domain of cGAS determines nucleo-cytoplasmic localization, enrichment on centromeres and activation of nuclear-localized cGAS. These results reveal a preferential functional association of nuclear cGAS with centromeres.
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Project description:Illumina sequencing data used in HIV-CRISPR screen with an ISG-specific sgRNA library (PIKAHIV) to find genes that block infection by the N74D and P90A HIV-1 capsid mutant viruses in THP-1 monocytic cells. For more information on the library and approach see Ohainle et al. eLife 2018 (PMID: 30520725). All screens performed here were done in a clonal ZAP-KO cell line (ZAP may inhibit the HIV-CRISPR vector used in the screen). Here we screen the Cyclophilin A-binding deficient mutant P90A and the CPSF6-binding deficient mutant N74D together with a wild type HIV-1 virus. The N74D screen was performed both with IFN treatment and without. These two HIV-1 capsid mutant viruses are hypersensitive to the effects of IFN.
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