Granzyme K, Regulated by the N6-Methyladenosine Methyltransferase Wilms’ tumor 1-associate protein, Enhances Myocardial Infarction Injury

Myocardial infarction (MI) is a major contributor to death in contemporary society, and this mechanism involves n6-methyladenosine (m⁶A) modification. In this study, we studied the m⁶A mechanisms involved in MI. For this purpose, an H9C2 cell MI model and MI rat model were developed. Cell Counting Kit-8 was applied to determine the effect of granzyme K (GZMK) differential expression on cell survival. In addition, 2,3,5-triphenyl tetrazolium chloride, hematoxylin-eosin, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, and enzyme-linked immunosorbent assay were performed to determine the effect of GZMK differential expression on myocardial injury markers, apoptosis, and inflammatory factors. The m⁶A-modification effect between Wilms' tumor 1-associate protein (WTAP) and GZMK was detected via methylated RNA immunoprecipitation. The expression of WTAP and GZMK in MI model cardiomyocytes was measured by quantitative reverse transcription polymerase chain reaction and western blotting. WTAP and GZMK were found to be highly expressed in MI H9C2 cells. Moreover, GZMK knockdown boosted cardiomyocyte proliferation, dampened the markers of myocardial injury and inflammation, and injured apoptosis in the MI model, whereas GZMK overexpression aggravated cardiomyocyte MI injury. GZMK was positively mediated by WTAP in cardiomyocytes and was subjected to WTAP-mediated m⁶A modification. The low expression of GZMK reduced the MI area, attenuated myocardial tissue damage and inflammation, and arrested cardiomyocyte apoptosis in the MI rats. Thus, for the first time, we demonstrated that GZMK was modified by WTAP via m⁶A modification, which promoted its expression in MI, thereby aggravating MI-induced myocardial injury.