Wilms' tumor 1-associated protein aggravates ischemic stroke by promoting M1 polarization of microglia by enhancing PTGS2 mRNA stability in an m6A-dependent manner.

Mounting evidence indicates the involvement of N6-methyladenosine (m6A) alterations in diverse neurological disorders and the activation of microglia. However, the role of m6A methyltransferase Wilms' tumor 1-associated protein (WTAP) in regulating microglial polarization during ischemic stroke (IS) remains unknown. We performed bioinformatics analysis to identify m6A-related differentially expressed genes in IS and validated these genes in a mouse middle cerebral artery occlusion model and a BV2 cell oxygen-glucose deprivation/reperfusion model. We found that microglial m6A modification was increased, and that WTAP was the most significantly differentially expressed m6A regulator during IS. High expression of WTAP is closely correlated with microglia-mediated neuroinflammation in IS. Mechanistically, WTAP promoted m6A modification, which promoted prostaglandin endoperoxide synthase-2 (PTGS2) by enhancing its mRNA stability. WTAP promoted M1 microglial polarization by elevating PTGS2 expression via m6A modification of PTGS2 mRNA in the oxygen-glucose deprivation/reperfusion model. In conclusion, WTAP is a crucial posttranscriptional regulator that contributes to post-IS neuroinflammation. WTAP knockdown confers cerebral protection by shifting the microglial phenotype from M1 to M2, primarily by reducing PTGS2 mRNA stability in an m6A-dependent manner.