FTO alleviates cerebral ischemia/reperfusion-induced neuroinflammation by decreasing cGAS mRNA stability in an m6A-dependent manner

Microglia-mediated inflammation is a major contributor to the brain damage in cerebral ischemia and reperfusion (I/R) injury, and N6-Methyladenosine (m6A) has been implicated in cerebral I/R injury. Here, we explored whether m6A modification is associated with microglia-mediated inflammation in cerebral I/R injury and its underlying regulatory mechanism using an in vivo mice model of intraluminal middle cerebral artery occlusion/reperfusion (MCAO/R) and in vitro models of primary isolated microglia and BV2 microglial cells subjected to oxygen-glucose deprivation and reoxygenation (OGD/R) were used. We found microglial m6A modification increased and microglial fat mass and obesity-associated protein (FTO) expression decreased in cerebral I/R injury in vivo and in vitro. Inhibition of m6A modification by intraperitoneal injection of Cycloleucine (Cyc) in vivo or transfection of FTO plasmid in vitro significantly alleviated brain injury and microglia-mediated inflammatory response. Through Methylated RNA immunoprecipitation sequencing (MeRIP-Seq), RNA sequencing (RNA-Seq) and western blotting, we found that m6A modification promoted cerebral I/R-induced microglial inflammation via increasing cGAS mRNA stability to aggravate Sting/NF-κB signaling. In conclusion, this study deepens our understanding on the relationship of m6A modification and microglia-mediated inflammation in cerebral I/R injury, and insights a novel m6A-based therapeutic for inhibiting inflammatory response against ischemic stroke.