TRPM7 promotes myocardial ischemia-reperfusion injury via CaMKII/DDX3X/NLRP3-mediated pyroptosis and m5C/ALYREF-dependent DDX3X stabilization

Abstract

Myocardial ischemia-reperfusion injury (MIRI) poses a major clinical challenge. This study aimed to elucidate whether TRPM7 regulates cardiomyocyte pyroptosis during MIRI and its underlying mechanisms. We established both in vivo (I/R-injured mice) and in vitro (H/R-injured HL-1 cardiomyocytes) models and employed multiple techniques including gene knockdown/overexpression, specific inhibitors (KN‑93 for CaMKII inhibition), protein‑protein interaction assays (Co‑IP, GST pull‑down), and m5C modification analysis (MeRIP, dual‑luciferase reporter assay with site‑directed mutagenesis). The results demonstrated that TRPM7 knockdown significantly improved cardiac function, reduced infarct area and myocardial fibrosis, and suppressed cell death in mice. Mechanistically, TRPM7‑mediated Ca 2+ influx activated CaMKII, which bound to and upregulated DDX3X. Concurrently, I/R‑ or H/R‑induced m5C modification on DDX3X mRNA recruited the m5C reader protein ALYREF, thereby stabilizing DDX3X expression. The elevated DDX3X subsequently activated the NLRP3 inflammasome, ultimately driving cardiomyocyte pyroptosis. Importantly, in vivo knockdown of DDX3X recapitulated the cardioprotective effects observed with TRPM7 inhibition. In conclusion, our findings reveal a critical role of a TRPM7‑initiated CaMKII/DDX3X/NLRP3 signaling axis in regulating pyroptosis during MIRI, providing a novel potential therapeutic target for this condition.