Regulation of endothelial cell senescence via the miR-217/FOXO3 axis

The accumulation of senescent endothelial cells within the endothelium leads to vascular dysfunction. Independent studies have linked miR-217, a senescence-associated microRNA and FOXO3, a longevity factor, to cellular senescence in different study models. However, their roles and direct interaction in endothelial replicative senescence (RS) remain to be investigated. This study sought to investigate the role of miR-217/FOXO3 axis in endothelial cell senescence. Young and RS HUVEC models were established to determine the differential mRNA and protein expressions of miR-217 and FOXO3 by RT-qPCR and immunoblotting. HUVECs were transfected with miR-217 mimic duplexes and hairpin inhibitors to evaluate the effects of elevated or reduced miR-217 expressions in endothelial health. FOXO3 was also stably knocked down using a lentiviral vector and rescue experiments were performed. RS HUVECs showed elevated senescence markers and miR-217 but decreased FOXO3 expressions. Dual-luciferase reporter assay confirmed FOXO3 as a direct miR-217 target. MiR-217 overexpression reduced FOXO3 but increased p16INK4a protein levels and impaired angiogenic potential in young HUVECs, suggesting that miR-217 promotes endothelial senescence and hampers angiogenesis by targeting FOXO3. Suppressing miR-217 increased FOXO3 expression in both RS and early-stage senescence (ES) HUVECs. However, ES but not RS HUVECs exhibited improved angiogenic potential. Meanwhile, FOXO3 knockdown increased miR-217 and p16INK4a expressions, indicating that FOXO3 loss drives endothelial senescence. However, transfection of FOXO3 knockdown cells with miR-217 inhibitor could only partially recover HUVECs angiogenic potential, suggesting that FOXO3 is critical for maintaining endothelial function. Collectively, these results showed that endothelial senescence and angiogenic potential are mediated through the crucial interaction of miR-217/FOXO3.