RNA <i>N</i>⁶-methyladenosine modulates endothelial atherogenic responses to disturbed flow in mice.

Abstract

Atherosclerosis preferentially occurs in atheroprone vasculature where human umbilical vein endothelial cells are exposed to disturbed flow. Disturbed flow is associated with vascular inflammation and focal distribution. Recent studies have revealed the involvement of epigenetic regulation in atherosclerosis progression. <i>N</i>⁶-methyladenosine (m⁶A) is the most prevalent internal modification of eukaryotic mRNA, but its function in endothelial atherogenic progression remains unclear. Here, we show that m⁶A mediates the epidermal growth factor receptor (EGFR) signaling pathway during EC activation to regulate the atherosclerotic process. Oscillatory stress (OS) reduced the expression of methyltransferase like 3 (METTL3), the primary m⁶A methyltransferase. Through m⁶A sequencing and functional studies, we determined that m⁶A mediates the mRNA decay of the vascular pathophysiology gene <i>EGFR</i> which leads to EC dysfunction. m⁶A modification of the <i>EGFR</i> 3' untranslated regions (3'UTR) accelerated its mRNA degradation. Double mutation of the <i>EGFR</i> 3'UTR abolished METTL3-induced luciferase activity. Adenovirus-mediated METTL3 overexpression significantly reduced EGFR activation and endothelial dysfunction in the presence of OS. Furthermore, thrombospondin-1 (TSP-1), an EGFR ligand, was specifically expressed in atheroprone regions without being affected by METTL3. Inhibition of the TSP-1/EGFR axis by using shRNA and AG1478 significantly ameliorated atherogenesis. Overall, our study revealed that METTL3 alleviates endothelial atherogenic progression through m⁶A-dependent stabilization of <i>EGFR</i> mRNA, highlighting the important role of RNA transcriptomics in atherosclerosis regulation.