PRKN-IMMT/MIC60 axis promotes myocardial ischemia-reperfusion injury via lysosomal degradation of GPX4

Mitochondrial damage is a pivotal driver of myocardial ischemia-reperfusion (MIR) injury. While PRKN (parkin RBR E3 ubiquitin protein ligase), a key E3 ubiquitin ligase in the PINK1 (PTEN induced kinase 1)-PRKN mitophagy pathway, has been extensively studied, its role and mechanisms in acute MIR injury remain incompletely understood. Here, we demonstrated that PRKN exacerbates MIR injury by promoting cardiomyocyte ferroptosis under hypoxia-reoxygenation (H/R) conditions. Mechanistically, PRKN interacts with and mediates the ubiquitination and proteasomal degradation of IMMT/MIC60 (inner membrane mitochondrial protein), a core mitochondrial inner membrane protein essential for cristae architecture and mitochondrial integrity. This disruption of IMMT facilitates lysosomal degradation of GPX4 (glutathione peroxidase 4), a major ferroptosis suppressor, thereby triggering ferroptosis. Consistent with these findings, cardiac-specific immt knockout mice displayed increased susceptibility to MIR injury in vivo. Our findings establish PRKN-driven IMMT degradation as a key pathological mechanism in MIR injury and identify the PRKN-IMMT axis as a potential therapeutic target for cardioprotection. Abbreviations: ATG5, autophagy related 5; ATP, adenosine triphosphate; CCCP, carbonyl cyanide m-chlorophenylhydrazone; CHX, cycloheximide; cKO, cardiomyocyte-specific knockout; CQ, chloroquine; CRISPR, clustered regularly interspaced short palindromic repeats; EF, ejection fraction; Fer-1, ferrostatin-1; FS, fractional shortening; GO, Gene Ontology; GPX4, glutathione peroxidase 4; GST, glutathione S-transferase; gRNA, guide RNA; hiPSC-CMs, human induced pluripotent stem cell-derived cardiomyocytes; H/R, hypoxia-reoxygenation; IF, immunofluorescence; IHC, immunohistochemistry; IMMT/MIC60, inner membrane mitochondrial protein; IP, immunoprecipitation; LoxP, locus of X-overP1; KO, knockout; KR, lysine residues mutated to arginine; MDA, malondialdehyde; MFN2, mitofusin 2; MIR, myocardial ischemia reperfusion; MMP, mitochondrial membrane potential; mPTP, mitochondrial permeability transition pore; mtROS, mitochondrial reactive oxygen species; NAC, N-acetylcysteine; OMM, outer mitochondrial membrane; PRKN, parkin RBR E3 ubiquitin protein ligase; RAB7, RAB7, member RAS oncogene family; RNA-seq, RNA sequencing; UB, ubiquitin; WB, western blot; WT, wild-type.