Project description:Mounting evidence indicates that the cGAS-STING pathway represents the major DNA sensing pathway to invoke immune and inflammatory responses in neuroinflammatory disorders. Here, we examinedgene expression profiling in the brain of cGAS and STING deficiency mice
Project description:Aims/hypothesis cGAS (cyclic GMP-AMP synthase) has been implicated in various cellular processes, but its role in β-cell proliferation and diabetes is not fully understood. This study investigates the impact of cGAS on β-cell proliferation, particularly in the context of diabetes. Methods Utilizing mouse models, including cGAS and STING (stimulator of interferon genes) knockout mice, we explored the role of cGAS in β-cell function. This involved β-cell-specific cGAS knockout (cGASβKO) mice, created by breeding cGAS floxed mice with transgenic mice expressing Cre recombinase under the insulin II promoter. We analyzed cGAS expression in diabetic mouse models, evaluated the effects of cGAS deficiency on glucose tolerance, and investigated the molecular mechanisms underlying these effects through RNA sequencing. Results Our study found that cGAS expression is upregulated in the islets of diabetic mice and in response to high glucose conditions in MIN6 cells. Global cGAS deficiency enhanced glucose tolerance, while β-cell-specific cGAS knockout improved glucose intolerance under high-fat diet conditions. Interestingly, STING knockout did not affect pancreatic β-cell mass, suggesting a STING-independent mechanism for cGAS's role in β-cells. Further analyses revealed that cGAS deficiency leads to increased β-cell proliferation and reduced expression of CEBPβ, a known suppressor of β-cell proliferation. This effect appears to be mediated by a STING-independent pathway and is specific to pancreatic tissue. Conclusions/interpretation Our findings indicate that cGAS plays a pivotal role in modulating β-cell proliferation and glucose homeostasis, potentially through regulating CEBPβ expression in a STING-independent manner. This study highlights the importance of cGAS in diabetes pathology and suggests it as a potential therapeutic target for enhancing β-cell proliferation in diabetes treatment.
Project description:DNA-protein crosslinks (DPCs) are severe DNA lesions that disrupt replication, transcription, and genome stability. However, their role in development and aging remains poorly understood. Here, we show that impaired SPRTN function, a metalloprotease essential for DPC repair during replication and mitosis, leads to DNA damage, mitotic abnormalities, and activation of the immune system. Notably, micronuclei formed upon SPRTN deficiency frequently contain DPCs, exhibit nuclear envelope rupture, and accumulate unrepaired DNA, thereby facilitating activation of the cGAS-STING pathway. Using a Sprtn knock-in mouse model of Ruijs Aalfs progeria syndrome, we demonstrate that chronic cGas-Sting activation drives inflammation, innate immune responses, and embryonic lethality. Surviving mice display a continuum of aging phenotypes from embryogenesis into adulthood. Genetic or pharmacological inhibition of cGas-Sting rescues embryonic viability and ameliorates progeroid features, linking DPC-induced innate immune activation to lifespan defects. Our findings uncover a previously unrecognized role for DPCs in coupling early developmental failure to premature aging.