Ischemia/reperfusion (IR) enhances oxidative stress, leading to myocardial injury. Although Perm1 promotes cytoprotective mechanisms, the underlying mechanisms are poorly understood. Cysteine oxidation of Keap1 alleviates Cul3-mediated ubiquitination/degradation of Nrf2 and promotes antioxidant transcription. Here we show that Perm1 activates Nrf2 through cysteine oxidation of Keap1 and stabilization of Nrf2. Endogenous Perm1 was downregulated during IR, whereas the rescue of Perm1 reduced IR injury. Downregulation of Perm1 exacerbated oxidative stress, whereas upregulation of Perm1 alleviated it, accompanied by downregulation and upregulation of Nrf2-regulated antioxidant genes, respectively. Perm1 promoted oxidation of cysteine residues in Keap1, possibly through thiol-disulfide exchange reactions, which decreases Keap1-Nrf2 interaction and inhibits Cul3-mediated degradation of Nrf2. We identified Cys121 and Cys746 in Perm1 as critical for Keap1 oxidation and cardioprotection. Thus, Perm1 induces cysteine oxidation of Keap1, thereby conferring myocardial resistance to IR injury by inducing Nrf2 stabilization and transcriptional activation of antioxidant genes.
Oka et al. (Tue,) studied this question.