MiR-155 Promotes Ox-LDL-induced Autophagy In Human Umbilical Vein Endothelial Cells By Targeting The PI3K/Akt/mTOR Pathway

Objective: Autophagy of endothelial cells has a protective role in inhibiting inflammation and against development of atherosclerosis,which regulated by mi R-155.We focus on this autophagy which has not been fully elucidated.In this report,we study the regulation mechanism of mi R-155 on autophagy of vascular endothelial cells and explore the targeting relationship of mi R-155 in PI3K/Akt/m TOR signaling pathway.Methods: We used human umbilical vein endothelial cells(HUVEC)model in vitro and using oxidized low-density lipoprotein(ox-LDL)stimulated cells to simulate the atherosclerosis.mi R-155 mimics,mi R-155 inhibitors,and negative control were transfected in HUVEC to alter the expression of mi R-155.We examined the autophagosomes with transmission electron microscopy(TEM).Laser scanning confocal microscopy was used to measure the levels of intracellular reactive fluorescent LC3 puncta.And we analyzed the expression levels of autophagy-associated protein LC3 with western blot.Prediction of the target genes of mi R-155 was performed by bioinformatics analyses and confirmed by a dual luciferase reporter assay.The expression levels of PI3 K and Rheb m RNA and proteins were detected by q RT-PCR and Western blot so that the association between mi R-155 and PI3 K and Rheb could be fully assessed.Results: We found that overexpression of mi R-155 promotes autophagy activity in oxidized low-density lipoprotein(ox-LDL)stimulated human umbilical vein endothelial cells(HUVEC),whereas inhibition expression of mi R-155 reduced autophagy activity.Besides,overexpression of mi R-155 negatively regulated autophagy dependently of the typical PI3K/Akt/m TOR signaling pathway.Importantly,we demonstrate that mi R-155 directly bound the PIK3 CA and Rheb 3′ untranslated region and inhibited its luciferase activity by a dual-luciferase reporter assay.Conclusion: we proved that mi R-155 promotes autophagy in vascular endothelial cells by targeting the PI3K/Akt/m TOR pathway.