METTL16 Contributes to Coronary Heart Disease by Inducing TET2 m6A Modification.

Background: Coronary heart disease (CHD) ranks as the primary cause of global morbidity and mortality. Despite of the progress in exploring risk factors and developing medications, considerable residual risk persists. In recent years, epigenetic regulation has emerged as a critical regulatory mechanism across various diseases. This study aimed to investigate the effects of methyltransferase-like protein 16 (METTL16) on CHD and the potential molecular mechanisms. Methods: A CHD mouse model was established and treated with METTL16 depletion treatment. The METTL16 RNA level was measured by qPCR assay. Cardiac function was estimated by using echocardiography. Tissue damage and cardiac fibrosis were analyzed by deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and Masson's trichrome staining. The blood samples were collected to measure lipid levels and cardiac function biomarkers. Vascular smooth muscle cells (VSMCs) were isolated, and cell viability and proliferation were detected by cell counting kit 8 (CCK-8) and colony formation assay. Cell apoptosis was determined by flow cytometry. Expression of apoptosis biomarkers was detected by Western blotting assay. The m6A enrichment on TET2 mRNA was determined by methylated RNA immunoprecipitation (MeRIP) assay and cross-Linking Immunoprecipitation and qPCR (CLIP-qPCR). Results: We observed elevated expression of METTL16 in cardiac tissues of CHD mice, and knockdown of METTL16 notably recovered the cardiac function, alleviated cardiac fibrosis, and decreased lipid levels. Knockdown of METTL16 suppressed VSMC proliferation and elevated cell apoptosis. METTL16 directly modulated the m6A enrichment on TET2 mRNA, and overexpression of TET2 could reverse the inhibitory effects of siMETTL16 on VSMC proliferation. Conclusion: METTL16 affects the cardiac damage and function during CHD via epigenetically modulating the m6A modification of TET2.