Exercise training ameliorates myocardial phenotypes in heart failure with preserved ejection fraction by changing N6-methyladenosine modification in mice model.

Heart failure with preserved ejection fraction (HFpEF) shows complicated and not clearly defined etiology and pathogenesis. Although no pharmacotherapeutics have improved the survival rate in HFpEF, exercise training has become an efficient intervention to improve functional outcomes. Here, we investigated N6-methyladenosine (mA) RNA methylation modification in a "two-hit" mouse model with HFpEF and HFpEF with exercise (HFpEF + EXT). The manner of mA in HFpEF and HFpEF + EXT hearts was explored mA-specific methylated RNA immunoprecipitation followed by high-throughput and RNA sequencing methods. A total amount of 3992 novel mA peaks were spotted in HFpEF + EXT, and 426 differently methylated sites, including 371 hypermethylated and 55 hypomethylated mA sites, were singled out for further analysis (fold change 2, 0.05). According to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, unique mA-modified transcripts in HFpEF + EXT were associated with apoptosis-related pathway and myocardial energy metabolism. HFpEF + EXT had higher total mA levels and downregulated fat mass and obesity-related (FTO) protein levels. Overexpression of FTO cancels out the benefits of exercise in HFpEF + EXT mice by promoting myocyte apoptosis, myocardial fibrosis and myocyte hypertrophy. Totally, mA is a significant alternation of epitranscriptomic processes, which is also a potentially meaningful therapeutic target.