OSGEP, A Negative Ferroptotic Regulator, Alleviates Cerebral Ischemia-Reperfusion Injury Through Modulating m6A Methylation of GPX4 mRNA

Cerebral ischemia-reperfusion injury (CIRI) is a devastating condition that triggers neuronal death and cerebral infarction. O-sialoglycoprotein endopeptidase (OSGEP), identified as a crucial element of the highly conserved KEOPS complex, regulated cellular proliferation and mitochondrial metabolism. Despite its known role in cellular homeostasis, the potential contribution of OSGEP to the development of CIRI remains elusive. This study was designed to investigate the potential role of ferroptosis in the pathogenesis of CIRI and indicate whether OSGEP could suppress ferroptosis to alleviate CIRI by modulating GPX4 m(6)A methylation. To this end, MCAO and OGD/R models were employed to closely simulate the CIRI. The potent ferroptosis inhibitors conferred prominent neuroprotection in both in vivo and in vitro models. Moreover, OSGEP expression level was not only downregulated in MCAO-treated mice and in cultured cerebrocortical neurons subjected to OGD/R, but also it was related to the prognosis of acute ischemic stroke (AIS) cases. Additionally, OSGEP overexpression exerted potent anti-ferroptotic effects in both MCAO and OGD/R models, while OSGEP depletion exhibited the opposite effect. Moreover, OSGEP regulated GPX4 expression by modulating m(6)A methylation of its mRNA. Furthermore, the inhibitory effect of OSGEP on ferroptosis was dependent on the presence of GPX4. Specifically, OSGEP knockout exacerbated ferroptosis-like cell death under MCAO condition. Besides, OSGEP regulated GPX4 mRNA stability through competition with YTHDC1 for binding to GPX4 mRNA and forming a complex with HNRNPUL1 in the neuronal primary cultures subjected to OGD/R. These findings highlighted the critical role of OSGEP, as a new contributing anti-ferroptotic factor, in the pathogenesis of CIRI.