O-GlcNAcylation of IGF2BP2 promotes angiogenesis after ischemic stroke by stabilizing PPP2CA in an m6A-dependent manner : O-GlcNAcylation of IGF2BP2 alleviates ischemic brain injury.

BACKGROUND: Angiogenesis is an important protective mechanism after ischemic stroke (IS). We aimed to investigate the effect of insulin like growth factor 2 mRNA binding protein 2 (IGF2BP2) O-GlcNAcylation in angiogenesis after IS. METHODS: IGF2BP2 O-GlcNAcylation and ubiquitination were detected by Co-immunoprecipitation. IGF2BP2 and PPP2CA mRNA binding relationship was verified by RNA immunoprecipitation (RIP) and RNA-pull down. Protein phosphatase 2 catalytic subunit alpha (PPP2CA) m6A modification level was measured by Methylated RIP. Cell viability, apoptosis and angiogenesis were assessed by Cell Counting Kit-8, TUNEL and tube formation assays. 2,3,5-Triphenyltetrazolium Chloride staining was used for infarct area, Nissl staining was used for neuronal damage. RESULTS: O-GlcNAc transferase (OGT) mediated O-GlcNAcylation of IGF2BP2 at the 162 serine site. O-GlcNAcylation stabilized IGF2BP2 by inhibiting its ubiquitination and degradation. O-GlcNAcylation of IGF2BP2 ameliorated brain injury in middle cerebral arterial occlusion/reperfusion (MCAO/R) rats by alleviating oxygen-glucose deprivation/reperfusion (OGD/R)-induced brain microvascular endothelial cell (BMEC) injury and promoting BMEC angiogenesis through the Hippo/Yes1-associated transcriptional regulator (YAP) signaling pathway. IGF2BP2 stabilized PPP2CA in an m6A-dependent manner. IGF2BP2 upregulated PPP2CA to reduce YAP phosphorylation and promote YAP nuclear translocation. CONCLUSION: O-GlcNAcylation of IGF2BP2 reduces its ubiquitination and degradation, thereby stabilizing PPP2CA by m6A modification. Upregulated PPP2CA drives dephosphorylation and nuclear translocation of YAP, which promotes angiogenesis to alleviate the injury after IS.