RNA methylation reading protein YTHDF2 relieves myocardial ischemia-reperfusion injury by downregulating BNIP3 via m6A modification.

ABSTRACT

BNIP3 is reported to be involved in hypoxia-induced mitochondrial defect and cell death in cardiomyocytes. However, little is known about the specific function and molecular mechanism of BNIP3-mediated mitophagy in myocardial ischemia-reperfusion injury (MIRI). Herein, this study explored the mechanism regulating BNIP3-modulated mitophagy in MIRI. Rat cardiomyocytes (H9c2 cells) underwent transfection and hypoxia/reoxygenation (H/R) treatment, followed by cell viability and apoptosis detection. Gain-of-function assays were conducted in rats before MIRI modeling, followed by the monitoring of cardiac changes and the evaluation of cardiac function, myocardial infarction area, and apoptosis in myocardial tissues. The levels of creatine kinase MB (CK-MB), cardiac troponin I (cTnI), lactic dehydrogenase (LDH), reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), p62, and LC3 II/LC3 I were tested in rat serum or H9c2 cells. The co-localization of LC3 and TOMM20 was analyzed. The interaction of BNIP3 with YTHDF2 was assessed. H/R treatment decreased cell viability and p62 and SOD levels while elevating cell apoptosis, the levels of CK-MB, cTnI, LDH, MDA, ROS, and LC3 II/LC3 I, the number of autophagosomes, and the co-localization of LC3 and TOMM20 in cardiomyocytes, which were neutralized by downregulating BNIP3 or upregulating YTHDF2. Moreover, upregulation of YTHDF2 repressed myocardial injury and mitophagy in MIRI rats. Mechanistically, YTHDF2 mediated BNIP3 expression by recognizing methylated BNIP3. Upregulation of BNIP3 counteracted the suppressive effect of YTHDF2 overexpression on H/R-induced injury and mitophagy in cardiomyocytes. The RNA methylation reading protein YTHDF2 ameliorated MIRI by downregulating BNIP3 via m6A modification.