Energy restriction inhibits β-catenin ubiquitination to improve ischemic stroke injury via USP18/SKP2 axis.

Ischemic stroke (IS) remains a global health issue because of its great disability and mortality. Energy restriction (ER) has been justified to perform an inhibitory role in cerebral injury caused by IS. This research was purposed to inquire the potential molecular mechanism of ER in IS. To verify the function of ER in the animal and cell models of IS, rats were subjected to intermittent fasting (IF) and middle cerebral artery occlusion/reperfusion (MCAO/R) surgery and HAPI cells were treated with oxygen-glucose deprivation and reoxygenation (OGD/R) and 2-deoxyglucose (2-DG). It was disclosed that IF mitigated brain damage and inflammation in MCAO/R rats. Likewise, ER inhibited OGD/R-evoked microglial activation and inflammatory response. Of note, ubiquitin specific protease 18 (USP18) was uncovered to be the most significantly upregulated in MCAO/R rats receiving IF compared to free-feeding MCAO/R rats. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot verified that ER led to the promotion of USP18 expression. Moreover, downregulation of USP18 neutralized the meliorative effects of ER on OGD/R-treated HAPI cells. Functionally, USP18 restrained β-catenin ubiquitination to enhance its expression. In addition, our results manifested that S-phase kinase associated protein 2 (SKP2) contributed to degradation of β-catenin and USP18 abolished the role of SKP2 in β-catenin ubiquitination. Knockout of USP18 eliminated the protective effects of IF on MCAO/R rats, while SKP2 exacerbated brain damage and inflammation by decreasing β-catenin expression after IF. In summary, we validated that ER-induced USP18 exerts a suppressive function in IS damage through SKP2-mediated β-catenin ubiquitination.