METTL14 Promotes Lipopolysaccharide-Induced Myocardial Damage via m6A-Dependent Stabilization of TRPM7 mRNA

Sepsis-induced myocardial injury (SIMI) is a vital pathological component of severe sepsis and septic shock. As a prevalent internal mRNA modification in eukaryotic cells, N6-methyladenosine (m6A) modification is implicated in sepsis and immune disorders. Methyltransferase-like 14 (METTL14), a core subunit of the methyltransferase complex that catalyzes messenger RNA m6A modification, is involved in the regulation of human cardiomyocyte cell line (AC16) injury. This study aimed to explore the role and mechanism of METTL 14 in lipopolysaccharide (LPS)-induced myocardial injury. Cell viability and apoptosis were analyzed via 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flow cytometry, and TdT-mediated dUTP nick-end labeling (TUNEL) assay. The Tumor necrosis factor alpha (TNF-alpha) and Interleukin-1beta (IL-1 beta) levels were analyzed via Enzyme linked immunosorbent assay (ELISA). Caspase-3 activity, reactive oxygen species activity, malondialdehyde level, and glutathione level were assessed using special assay kits. The levels of transient receptor potential melastatin 7 (TRPM7) and METTL14 mRNA were determined via Real-time quantitative polymerase chain reaction (RT-qPCR). Meanwhile, the protein levels of TRPM7, METTL14, phospho-p65 (p-p65), total p65 (p65), p-I kappa B alpha, and total I kappa B alpha (I kappa B alpha) were examined via western blot assay. LPS treatment repressed AC16 cell viability and induced cell apoptosis, inflammatory response, oxidative stress, and ferroptosis in vitro. METTL14 and TRPM7 were upregulated in LPS-treated AC16 cells. At the molecular level, METTL14 could increase the stability of TRPM7 mRNA via m6A methylation. Moreover, METTL14 deficiency could abolish LPS-triggered AC16 cell injury and ferroptosis via TRPM7 regulation. METTL14 knockdown reversed LPS-caused myocardial cell damage mainly by regulating the stability of TRPM7 mRNA, providing a novel therapeutic target for septic cardiomyopathy treatment.