Project description:The cyclic GMP-AMP synthase (cGAS) recognizes Y-form cDNA of HIV-1 and initiate the antiviral immune response through cGAS–STING–TBK1–IRF3–type I IFN (IFN-I) signaling cascade. HIV-1 uses several strategies to interfere with the host immune molecules and mediate immune evasion. However, the potential role of HIV-1 proteins in cGAS–STING signaling remains unclear. Here we report that the HIV-1 protein p6 suppresses HIV-1-stimulated expression of IFN-I and promotes the immune evasion. Mechanistically, p6 bound with STING and inhibited the activation of STING and the interaction between STING and TBK1. Moreover, the glutamylation of p6 at Glu6 residue inhibited the interaction between STING and TRIM32 or AMFR, which subsequently suppressed the K27- and K63-linked polyubiquitination of STING at Lys337, therefore inhibited STING activation and type I IFN production, while the mutation of Glu6 residue lost the inhibitory effect. However, CoCl2, an agonist for cytosolic carboxypeptidases (CCPs), counteracted the glutamylation of Glu6 residue of p6 and promoted IFN-I production to block the immune evasion of HIV-1. These findings not only reveal a previously unknown mechanism through which an HIV-1 protein mediate immune evasion, but also provide a new therapeutic drug candidate to treat HIV-1 infection.
Project description:Virus infection may induce excessive interferon (IFN) responses that can lead to host tissue injury or even death. β-arrestin 2 regulates multiple cellular events through the G protein-coupled receptor (GPCR) signaling pathways. Here we demonstrate that β-arrestin 2 also promotes virus-induced production of IFN-β and clearance of viruses in macrophages. β-arrestin 2 interacts with cyclic GMP-AMP synthase (cGAS) and increases the binding of dsDNA to cGAS to enhance cyclic GMP-AMP (cGAMP) production and the downstreatm stimulator of interferon genes (STING) and innate immune responses. Mechanistically, deacetylation of β-arrestin 2 at Lys171 facilitates the activation of the cGAS–STING signaling and the production of IFN-β. In vitro, viral infection induces the degradation of β-arrestin 2 to facilitate immune evasion, while a β-blocker, carvedilol, rescues β-arrestin 2 expression to maintain the antiviral immune response. Our results thus identify a viral immune-evasion pathway via the degradation of β-arrestin 2, and also hint that carvedilol, approved for treating heart failure, can potentially be repurposed as an antiviral drug candidate.
Project description:Low-grade inflammation is a hallmark of old age and a central driver of ageing-associated impairment and disease. Multiple factors can contribute to ageing-associated inflammation, however the molecular pathways transducing aberrant inflammatory signalling and their impact in natural ageing remain poorly understood. Here we show that the cGAS-STING signalling pathway, mediating immune sensing of DNA, is a critical driver of chronic inflammation and functional decline during ageing. Blockade of STING suppresses the inflammatory phenotypes of senescent human cells and tissues, attenuates ageing-related inflammation in multiple peripheral organs and the brain in mice, and leads to an improvement in tissue function. Focusing on the ageing brain, we reveal that activation of STING triggers reactive microglia transcriptional states, neurodegeneration and cognitive decline. Cytosolic DNA released from perturbed mitochondria elicits cGAS activity in old microglia defining a mechanism by which cGAS-STING signalling is engaged in the ageing brain. Single-nuclei RNA-sequencing (snRNA-seq) of microglia and hippocampi of a newly developed cGAS gain-of-function mouse model demonstrates that engagement of cGAS in microglia is sufficient to direct ageing-associated transcriptional microglia states leading to bystander cell inflammation, neurotoxicity and impaired memory capacity. Our findings establish the cGAS-STING pathway as a critical driver of ageing-related inflammation in peripheral organs and the brain, and reveal blockade of cGAS-STING signalling as a potential strategy to halt (neuro)degenerative processes during old age.
Project description:Low-grade inflammation is a hallmark of old age and a central driver of ageing-associated impairment and disease. Multiple factors can contribute to ageing-associated inflammation, however the molecular pathways transducing aberrant inflammatory signalling and their impact in natural ageing remain poorly understood. Here we show that the cGAS-STING signalling pathway, mediating immune sensing of DNA, is a critical driver of chronic inflammation and functional decline during ageing. Blockade of STING suppresses the inflammatory phenotypes of senescent human cells and tissues, attenuates ageing-related inflammation in multiple peripheral organs and the brain in mice, and leads to an improvement in tissue function. Focusing on the ageing brain, we reveal that activation of STING triggers reactive microglia transcriptional states, neurodegeneration and cognitive decline. Cytosolic DNA released from perturbed mitochondria elicits cGAS activity in old microglia defining a mechanism by which cGAS-STING signalling is engaged in the ageing brain. Single-nuclei RNA-sequencing (snRNA-seq) of microglia and hippocampi of a newly developed cGAS gain-of-function mouse model demonstrates that engagement of cGAS in microglia is sufficient to direct ageing-associated transcriptional microglia states leading to bystander cell inflammation, neurotoxicity and impaired memory capacity. Our findings establish the cGAS-STING pathway as a critical driver of ageing-related inflammation in peripheral organs and the brain, and reveal blockade of cGAS-STING signalling as a potential strategy to halt (neuro)degenerative processes during old age.
Project description:Low-grade inflammation is a hallmark of old age and a central driver of ageing-associated impairment and disease. Multiple factors can contribute to ageing-associated inflammation, however the molecular pathways transducing aberrant inflammatory signalling and their impact in natural ageing remain poorly understood. Here we show that the cGAS-STING signalling pathway, mediating immune sensing of DNA, is a critical driver of chronic inflammation and functional decline during ageing. Blockade of STING suppresses the inflammatory phenotypes of senescent human cells and tissues, attenuates ageing-related inflammation in multiple peripheral organs and the brain in mice, and leads to an improvement in tissue function. Focusing on the ageing brain, we reveal that activation of STING triggers reactive microglia transcriptional states, neurodegeneration and cognitive decline. Cytosolic DNA released from perturbed mitochondria elicits cGAS activity in old microglia defining a mechanism by which cGAS-STING signalling is engaged in the ageing brain. Single-nuclei RNA-sequencing (snRNA-seq) of microglia and hippocampi of a newly developed cGAS gain-of-function mouse model demonstrates that engagement of cGAS in microglia is sufficient to direct ageing-associated transcriptional microglia states leading to bystander cell inflammation, neurotoxicity and impaired memory capacity. Our findings establish the cGAS-STING pathway as a critical driver of ageing-related inflammation in peripheral organs and the brain, and reveal blockade of cGAS-STING signalling as a potential strategy to halt (neuro)degenerative processes during old age.
Project description:Low-grade inflammation is a hallmark of old age and a central driver of ageing-associated impairment and disease. Multiple factors can contribute to ageing-associated inflammation, however the molecular pathways transducing aberrant inflammatory signalling and their impact in natural ageing remain poorly understood. Here we show that the cGAS-STING signalling pathway, mediating immune sensing of DNA, is a critical driver of chronic inflammation and functional decline during ageing. Blockade of STING suppresses the inflammatory phenotypes of senescent human cells and tissues, attenuates ageing-related inflammation in multiple peripheral organs and the brain in mice, and leads to an improvement in tissue function. Focusing on the ageing brain, we reveal that activation of STING triggers reactive microglia transcriptional states, neurodegeneration and cognitive decline. Cytosolic DNA released from perturbed mitochondria elicits cGAS activity in old microglia defining a mechanism by which cGAS-STING signalling is engaged in the ageing brain. Single-nuclei RNA-sequencing (snRNA-seq) of microglia and hippocampi of a newly developed cGAS gain-of-function mouse model demonstrates that engagement of cGAS in microglia is sufficient to direct ageing-associated transcriptional microglia states leading to bystander cell inflammation, neurotoxicity and impaired memory capacity. Our findings establish the cGAS-STING pathway as a critical driver of ageing-related inflammation in peripheral organs and the brain, and reveal blockade of cGAS-STING signalling as a potential strategy to halt (neuro)degenerative processes during old age.
Project description:Stimulator of interferon genes (STING), the central hub protein of the cGAS-STING signaling, is essential for type I IFN production of innate immunity. However, prolonged or excessive activation of STING is highly related to autoimmune diseases, most of which exhibit the hallmark of elevated expression of type I interferons and IFN-stimulated genes (ISGs). Thus, the activity of STING must be stringently controlled to maintain immune homeostasis. Here, we reported that CK1α, a protein serine/threonine kinase, was essential to prevent the over-activation of STING-mediated type I IFN signaling through autophagic degradation of STING. Mechanistically, CK1α interacted with STING upon the cGAS-STING pathway activation and promoted STING autophagic degradation by enhancing the phosphorylation of p62 at serine 349, which was critical for p62 mediated STING autophagic degradation. Consistently, SSTC3, a selective CK1α agonist, significantly attenuated the response of the cGAS-STING signaling by promoting STING autophagic degradation. Importantly, pharmaceutical activation of CK1α using SSTC3 markedly repressed the systemic autoinflammatory responses in the Trex1-/- mouse autoimmune disease model and effectively suppressed the production of IFNs and ISGs in the PBMCs of SLE patients. Taken together, our study reveals a novel regulatory role of CK1α in the autophagic degradation of STING to maintain immune homeostasis. Manipulating CK1α through SSTC3 might be a potential therapeutic strategy for alleviating STING-mediated aberrant type I IFNs in autoimmune diseases.
Project description:We show that Manganese (II) is a potent type I-IFN inducing agonist, stimulating cells into an anti-viral state in the absence of infection. Mechanically, Mn2+ treatment led to a profound cGAS-STING-dependent innate immune activation, conferring cells or mice viral resistance.
Project description:We investigated the cGAS-STING inflammatory pathway differential activity among both sexes in T2DN rats and its impact on the temporal progression of the diabetic kidney disease. Here we used both male and female old and young T2DN rats. The cGAS-STING pathway presented distinct protein expression profiles between male and female T2DN rats, which significantly intensify with aging. In male T2DN rats, pro-inflammatory genes are particularly heightened in comparison to female rats of similar age, and such levels are further exacerbated with age. Interestingly, a comprehensive RNA-Seq analysis conducted in the kidney cortex of both sexes of T2DN rats, in younger and older ages, disclosed several central molecules, with crucial genes identified within the cGAS-STING pathway. Our study showed the intricate sexual differences in the development and progression of DKD and proposed the fundamental role of cGAS-STING pathway in disease development.