Neural stem cell-derived exosomal PA2G4 induces ANXA2 degradation to promote mitophagy and alleviate neuronal oxidative stress in cerebral ischemia/reperfusion.

Cerebral ischemia/reperfusion injury (CI/RI) is a common complication of cerebrovascular diseases such as stroke, characterized by mitochondrial dysfunction. This study investigates the function of proliferation-associated protein 2G4 (PA2G4) released by neural stem cells (NSCs)-derived exosomes (NSC-Exo) in treating middle cerebral artery occlusion/reperfusion (MCAO/R) by regulating mitophagy. NSC-Exo were extracted and identified. Treatment of NSC-Exo alleviated neurofunctional impairments in MCAO/R-induced mice, reduced oxidative stress and inflammatory responses in hippocampal tissues, and decreased neuronal apoptosis. We analyzed the alteration of molecular mechanisms under the effect of NSC-Exo treatment using bioinformatics analysis and RNA sequencing. PA2G4 was enriched in NSC-Exo, and the absence of PA2G4 in neurons impaired the mitigating effect of NSC-Exo on hippocampal neuronal injury and inhibited mitophagy. NSC-Exo delivered PA2G4 to recruit WW domain-containing protein 2 (WWP2), thereby mediating ubiquitination and degradation of Annexin A2 (ANXA2), and overexpression of PA2G4 or WWP2 reversed the accentuating effect of ANXA2 overexpression on MCAO injury. These findings indicate that PA2G4 delivered by NSC-Exo recruits WWP2 to mediate ubiquitination of ANXA2, thereby activating mitophagy to alleviate oxidative stress in hippocampal neurons in MCAO/R. This study offers a novel target for the treatment of CI/RI.