Role of N6-methyladenosine methylation in transverse aortic constriction-induced cardiac fibrosis: insights from MeRIP-seq analysis

This study aimed to investigate the role and potential mechanisms of N6-methyladenosine (m6A) methylation in a mouse model of transverse aortic constriction (TAC)-induced cardiac fibrosis using MeRIP-seq. A TAC-induced cardiac fibrosis mouse model was established, and cardiac function and structural parameters were assessed by echocardiography four weeks post-surgery. The global m6A methylation levels in myocardial tissues were evaluated using Dot blot analysis, and the expression levels of m6A-modifying enzymes (METTL3, METTL14, ALKBH5, FTO) were detected by qPCR and Western blot. Additionally, methylated RNA immunoprecipitation sequencing (MeRIP-Seq) was performed to identify differentially methylated sites, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses to determine the biological functions and signaling pathways of m6A-methylated genes. The results showed that TAC surgery successfully induced a cardiac fibrosis model in mice, as indicated by significantly reduced EF and LVEF and increased LVIDd and LVIDs. Moreover, m6A methylation levels were elevated in myocardial tissues of TAC mice, accompanied by upregulation of METTL3 and METTL14 expressions and downregulation of ALKBH5 and FTO expression. MeRIP-seq revealed that m6A peaks were primarily enriched in the 3' UTR regions, with 1,466 differentially methylated sites identified between TAC and sham groups, including 717 hypermethylated and 749 hypomethylated sites. Functional enrichment analyses showed that these differentially methylated genes were involved in various biological processes, including signal transduction, transcriptional regulation, and ion channel activity, and were associated with pathways such as type 2 diabetes mellitus, signaling pathways regulating pluripotency of stem cells, and insulin signaling. Thus, our findings suggested that m6A methylation played a significant role in TAC-induced cardiac fibrosis by regulating key genes involved in myocardial remodeling and functional impairment.