Project description:Microbial infection, the strong trigger to directly induce inflammation in brain, is long considered a risk factor of Alzheimer's disease (AD), but how these infections contribute to neurodegeneration remains underexplored. To examine the effect of herpes simplex virus type 1 (HSV-1) infection on tauopathy in local hippocampus of P301S mice, we utilized a modified HSV-1 strain (mHSV-1) potentially relevant to AD, we found that its infection promotes tau-related pathology in part via activating neuroimmune cGAS-STING pathway in the tau mouse model. Specifically, Sting ablation causes the detectable improvement of neuronal dysfunction and loss in P301S mice, which is causally linked to lowered proinflammatory status in the brain. Administration of STING inhibitor H-151 alleviates neuroinflammation and tau-related pathology in P301S mice. These results jointly suggest that herpesviral infection, as the vital environmental risk factor, could induce tau-related pathology in AD pathogenesis partially via neuroinflammatory cGAS-STING pathway.
Project description:Microbial infection, the strong trigger to directly induce inflammation in brain, is long considered a risk factor of Alzheimer's disease (AD), but how these infections contribute to neurodegeneration remains underexplored. To examine the effect of herpes simplex virus type 1 (HSV-1) infection on tauopathy in local hippocampus of P301S mice, we utilized a modified HSV-1 strain (mHSV-1) potentially relevant to AD, we found that its infection promotes tau-related pathology in part via activating neuroimmune cGAS-STING pathway in the tau mouse model. Specifically, Sting ablation causes the detectable improvement of neuronal dysfunction and loss in P301S mice, which is causally linked to lowered proinflammatory status in the brain. Administration of STING inhibitor H-151 alleviates neuroinflammation and tau-related pathology in P301S mice. These results jointly suggest that herpesviral infection, as the vital environmental risk factor, could induce tau-related pathology in AD pathogenesis partially via neuroinflammatory cGAS-STING pathway.
Project description:Ageing and age-related brain disorders are typically concomitant with cellular mitochondrial dysfunction and metabolic dysregulation in immune cells. However, whether and how immunometabolic dysregulation in the brain affects neurological function are incompletely understood. Here we reveal the presence of metabolic dysregulation within microglia, the brain-resident immune cells, in aged mice. We discover that microglia with dysregulated immunometabolism, induced by dysfunctional mitochondria, initially act as triggers of brain ageing-related neurological dysfunctions in mice, which are mechanistically driven by microglial immunometabolic disturbance-induced inflammaging response depending on neuroimmune cGAS-STING pathway. We present evidence that a combined treatment targeting both metabolism and neuroinflammation partially rescues brain ageing in mice. These findings establish a causal link between immunometabolism, neuroimmunity, and brain ageing, underscoring the significance of tightly regulated immunometabolism in age-associated neurological diseases.
Project description:The cGAS-STING pathway, a central component of the innate immune system, senses cytosolic DNA and induces interferon-stimulated genes (ISGs) to mediate inflammation. Here we report the unexpected discovery that cGAS senses dysfunctional protein production. Purified ribosomes interact with and stimulate the catalytic activity of recombinant cGAS in vitro. Disruption of the ribosome-associated protein quality control pathway, which detects and resolves ribosome collisions, results in cGAS- and STING-dependent ISG expression, and causes the re-localization of cGAS from the nucleus to the cytosol. Indeed, cGAS preferentially binds collided ribosomes in vitro, and other orthogonal perturbations that lead to elevated levels of collided ribosomes cause re-localization of cGAS as well. Thus, the cGAS-STING pathway senses and responds to translation stress. These findings have implications for the inflammatory responses to viral infection and tumorigenesis, both of which substantially reprogram cellular protein synthesis.
Project description:The strongest risk factors for Alzheimer’s disease (AD) include the 4 allele of apolipoprotein E (APOE), the R47H variant of triggering receptor expressed on myeloid cells 2 (TREM2), and female sex. Here, we combine APOE4 and TREM2R47H (R47H) in female P301S tauopathy mice to identify the pathways activated when AD risk is the strongest, thereby highlighting detrimental disease mechanisms. We find that the R47H variant induces neurodegeneration in 9- to- 10-month-old female APOE4 tauopathy mice. The combination of APOE4 and R47H (APOE4-R47H) worsened hyperphosphorylated tau pathology in the frontal cortex and amplified tauopathy-induced cell-autonomous microglial cGAS-STING signaling and downstream interferon response. APOE4-R47H microglia displayed cGAS- and BAX-dependent upregulation of senescence, showing association between neurotoxic signatures and implicating mitochondrial permeabilization in pathogenesis. By uncovering pathways enhanced by the strongest AD risk factors, our study points to cGAS-STING signaling and associated microglial senescence as potential drivers of AD risk.
Project description:The cGAS-STING signalling has been well recognized as the major pathway response to self and non-self DNA molecule in cytoplasm. Here, we measured the temporal transcriptome dynamic changes after cGAS-STING signalling activation based on cGAS specific agonist G3-YSD transfection
Project description:The cytosolic DNA sensor cyclic GMP-AMP (cGAMP) synthetase (cGAS) has emerged as a fundamental component fueling the anti-pathogen immunity. Because of its pivotal role in initiating innate immune response, the activity of cGAS must be tightly fine-tuned to maintain immune homeostasis in antiviral response. Here, we reported that neddylation modification was indispensable for appropriate cGAS-STING signaling activation. Blocking neddylation pathway using neddylation inhibitor MLN4924 substantially impaired the induction of type I interferon and proinflammatory cytokines, which was selectively dependent on Nedd8 E2 enzyme Ube2m. We further found that deficiency of the Nedd8 E3 ligase Rnf111 greatly attenuated DNA-triggered cGAS activation while not affecting cGAMP induced activation of STING, demonstrating that Rnf111 was the Nedd8 E3 ligase of cGAS. We further identified Lys231 and Lys421 as the key neddylation sites in human cGAS. Mechanistically, Rnf111 interacted with and polyneddylated cGAS, which in turn promoted its dimerization and enhanced the DNA-binding ability, leading to proper cGAS-STING pathway activation. In the same line, the Ube2m or Rnf111 deficiency mice exhibited severe defects in innate immune response and were susceptible to HSV-1 infection. Collectively, our study uncovered a vital role of the Ube2m-Rnf111 neddylation axis in promoting the activity of the cGAS-STING pathway and highlighted the importance of neddylation modification in antiviral defense.
Project description:The cGAS-STING pathway, a central component of the innate immune system, senses cytosolic DNA and induces interferon-stimulated genes (ISGs) to mediate inflammation. Here we report the unexpected discovery that cGAS senses dysfunctional translation. Purified ribosomes interact with and stimulate recombinant cGAS catalytic activity in vitro. Disruption of the ribosome-associated protein quality control pathway, which detects and resolves ribosome collisions, results in cGAS- and STING-dependent ISG expression, and cause the re-localization of cGAS from the nucleus to the cytosol. Other orthogonal perturbations that lead to elevated levels of collided ribosomes cause re-localization of cGAS as well. Thus, the cGAS-STING pathway senses and responds to translation stress. These findings have implications for the inflammatory responses to viral infection and tumorigenesis, both of which substantially reprogram cellular protein synthesis.
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.