Abstract
BackgroundAtherosclerosis is a chronically inflammatory disease and one of the leading causes of deaths worldwide. Endothelial cell apoptosis plays a crucial role in its development. Several microRNAs (miRNAs) are reportedly involved in atherosclerotic plaque formation, including miRNA-210 (miR-210). However, the underlying mechanism of its role in endothelial cell apoptosis during atherosclerosis is still largely unknown.MethodsA mouse model with atherosclerosis induced by a high-fat diet (HFD) was built in ApoE (-/-) mice. The levels of endothelial cell apoptosis were determined via flow cytometry. The expressions of miR-210 and PDK1 in purified CD31+ endothelial cells from mouse aorta were measured via RT-qPCR and western blot. Binding between miR-210 and the 3′-untranslated region (UTR) of PDK1 mRNA was predicted using bioinformatics analyses and confirmed with a dual luciferase reporter assay. The effects of miR-210 were further analyzed in an in vitro model using human aortic endothelial cells (HAECs) treated with oxidized low-density lipoprotein (ox-LDL).ResultsWe found that the HFD mice developed atherosclerosis in 12 weeks and had a significantly higher percentage of endothelial cell apoptosis. The upregulated level of miR-210 in the HFD mice and HAECs inversely correlated with the level of PDK1. Inhibiting miR-210 expression significantly reduced HAEC apoptosis, as evidenced by the results of the MTT and flow cytometry experiments. Further analysis identified PDK1 as the target of miR-210 and showed that PDK1 overexpression reversed the pro-apoptotic effect of miR-210 through mediation of the P13K/Akt/mTOR pathways.ConclusionOur study suggests a novel role for miR-210 in the progression of atherosclerosis through the regulation of endothelial apoptosis. This indicates that miR-210 might have potential in treatment of atherosclerosis.
Highlights
Atherosclerosis is a chronically inflammatory disease and one of the leading causes of deaths worldwide
We found that miR-210 was upregulated by directly targeting 3phosphoinositide-dependent protein kinase-1 (PDK1) in vascular endothelial cells in an atherosclerosis mouse model and in human aortic endothelial cells (HAECs) treated with oxidized low-density lipoprotein
Western blot results for CD31+ endothelial cells showed that the levels of crucial pro-apoptosis proteins, such as Bax, caspase-9 and caspase-3, had notably increased, while the level of the anti-apoptosis protein Bcl-2 had significantly decreased in high-fat diet (HFD) mice compared to NOR mice (Fig. 2b)
Summary
Atherosclerosis is a chronically inflammatory disease and one of the leading causes of deaths worldwide. The underlying mechanism of its role in endothelial cell apoptosis during atherosclerosis is still largely unknown. Atherosclerosis, which is an inflammatory disease and a predominant cause of cardiovascular disorders, is a worldwide issue due to the prevalence of diets high in saturated fats and lipids [1, 2]. Atherogenic lipoproteins, especially lowdensity lipoprotein (LDL) cholesterol, build up to gradually form atherosclerotic plaques, which have been proven to be involved in atherosclerosis-related morbidity [3, 4]. ApoE (-/-) mice fed with high-fat diets (HFD) display high lipid levels, excessive cholesterol in the blood vessels and atherosclerotic symptoms [9], making this an acknowledged model for investigating atherosclerosis [10]. Preventing EC apoptosis has garnered considerable attention as a novel means of treating atherosclerosis [16, 17]
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