m6A Methyltransferases RBM15 Regulates Vascular Endothelial Cell Injury and Senescence via Promoting the Expression of SIRT6

Background: Endothelial cell injury and dysfunction are the critical steps in the formation of atherosclerosis. N6-methyladenosine modification (m6A) has been reported to participate in various diseases. In this work, we aimed to study the effects of methyltransferases RNA-binding motif protein 15 (RBM15) on vascular endothelial cell injury and senescence. Methods: HUVECs were stimulated with oxidized low-density lipoprotein (ox-LDL) to establish in vitro model. Cell viability was measured by cell counting kit 8 (CCK-8). Protein and RNA expression correlated with oxidative stress and cell senescence were by western blot and quantitative PCR (qPCR) assay. Production of inflammatory cytokines was detected by Enzyme-linked immunosorbent assay (ELISA). SA-β-Gal assay was performed to evaluate cell senescence. Cell injury was measured by SOD activity and MDA level. The m6A enrichment on SIRT6 and mRNA stability were detected by MeRIP assay and actinomycin D treatment, respectively. Results: The ox-LDL suppressed the viability, induced production of proinflammatory factors TNF-α, IL-6, and IL-1β, downregulated RBM15 expression, and induced senescence in HUVECs, whereas overexpression of RBM15 reversed these effects. RBM15 elevated the m6A enrichment and enhanced SIRT6 mRNA stability and expression. Knockdown of SIRT6 abolished the protective effects of RBM15 on HUVECs. Conclusion: RBM15 epigenetically regulated the m6A enrichment of SIRT6 in vascular endothelial cells to alleviate cell injury and senescence.