METTL3-mediated N6-methyladenosine modification of Dnajb1 modulates cardiomyocyte ferroptosis during myocardial infarction.

Myocardial infarction (MI) affects millions of individuals worldwide, with ferroptosis recognized as a pivotal regulated cell death pathway in this context. N6-methyladenosine (m6A), the most prevalent mRNA modification, is essential in modulating RNA splicing, export, stability, and translation during MI progression. Nonetheless, the involvement of m6A modification in cardiomyocyte ferroptosis has yet to be elucidated. This study aimed to elucidate the regulatory mechanisms of m6A modification in cardiomyocyte ferroptosis by conducting an integrated analysis of methylated RNA immunoprecipitation-sequencing and RNA-sequencing data obtained from myocardial tissues of MI mice, to identify promising therapeutic strategies for MI. We demonstrated that the differentially m6A-modified DnaJ heat shock protein family member B1 (Dnajb1) gene suppressed ferroptosis during the pathological process of MI. DNAJB1 overexpression protected against hypoxia-induced cardiomyocyte ferroptosis by suppressing pro-ferroptotic effectors. Mechanistically, methyltransferase-like 3 (METTL3) bound to Dnajb1, enhancing its m6A modification and diminishing mRNA stability, while insulin-like growth factor 2 mRNA-binding protein 3 competes for binding and increases mRNA stability. DNAJB1 prevented hypoxia-induced glutathione depletion and lipid peroxidation by inhibiting glutathione peroxidase 4 degradation via the autophagic-lysosomal pathway. In vivo, DNAJB1 overexpression improved heart function, reduced infarct size and fibrosis, and lowered plasma malondialdehyde levels in MI mice, whereas METTL3 co-overexpression counteracted these cardioprotective effects. Overall, this study uncovers a METTL3/Dnajb1 pathway in cardiomyocyte ferroptosis during MI. METTL3 modifies Dnajb1 through m6A, destabilizing its mRNA and weakening glutathione peroxidase 4-dependent antioxidant defense, thus promoting ferroptosis. These insights into epitranscriptomic regulation of cell death highlight potential therapeutic targets to prevent ferroptosis-related cardiac damage.