Search

Atherosclerosis (AS) is a chronic inflammatory disease that damages the arterial wall as a result of hyperlipidemia and causes endothelial cell dysfunction, which increases the risk of atherothrombotic events. Multiple pathological conditions have shown ectopic miR-199a-5p levels to cause endothelial injury, but its role in the AS competitive endogenous RNA (CeRNA) network is still unknown. The high-fat diet (HFD) apoE−/− mouse model was constructed in vivo, and ECs were cultured under ox-LDL treatment to induce EC injury in vitro. Immunohistochemistry and immunofluorescence staining were used to assess the effect of miR-199a-5p on the macrophage, SMC, collagen content, and endothelial coverage in the artery wall of mouse model. miR-199a-5p level was validated to be overexpression in the aorta tissue of HFD apoE−/− mice and in the ox-LDL-treated ECs, and even in the plasma EVs of the patients with cerebral AS. Silencing of miR-199a-5p significantly attenuated atherosclerotic progress in HFD apoE−/− mice, and the gain/loss-of-function assay indicated that miR-199a-5p overexpression aggravated ox-LDL-induced disabilities of endothelial proliferation, motility, and neovascularization based on cell counting kit-8 assay, transwell assay and matrigel assay. Mechanistically, miR-199a-5p prevented EC activation by activating the FOXO signaling pathway by targeting SIRT1. Additionally, circular RNA (circRNA) circHIF1ɑ was identified as having a low expression in the ox-LDL-treated EC and mediated SIRT1 expression via sponging miR-199a-5p to rescue ox-LDL-induced EC injury. Our study demonstrated the vital role of miR-199a-5p/SIRT1 axis regulated by circHIF1ɑ in AS pathogenesis and provided novel effective targets for AS treatment. • Vascular atherosclerosis is the most leading cause of cardiovascular or cerebrovascular disorders. It is crucial to identify and develop various diagnostic and treatment strategies to treat atherosclerosis. • Our study aimed to identify the miR-199a-5p/SIRT1 axis regulated by circHIF1ɑ in the pathogenesis of atherosclerosis. • miR-199a-5p could be a potential diagnostic marker for atherosclerosis development and progression, and circHIF1ɑ/miR-199a-5p axis could be used as a potential treatment strategy to treat atherosclerosis. [ABSTRACT FROM AUTHOR]

Introduction: Hypoxia-inducible factor (HIF)1α has been shown to be activated and induces a glycolytic shift under hypoxic condition, however, little attention was paid to the role of HIF1α-actuated fructolysis in hypoxia-induced heart injury. Objectives: In this study, we aim to explore the molecular mechanisms of miR-155-mediated fructose metabolism in hypoxic cardiac fibroblasts (CFs). Methods: Immunostaining, western blot and quantitative real-time reverse transcription PCR (qRT-PCR) were performed to detect the expression of glucose transporter 5 (GLUT5), ketohexokinase (KHK)-A and KHK-C in miR-155−/− and miR-155wt CFs under normoxia or hypoxia. A microarray analysis of circRNAs was performed to identify circHIF1α. Then CoIP, RIP and mass spectrometry analysis were performed and identified SKIV2L2 (MTR4) and transformer 2 alpha (TRA2A), a member of the transformer 2 homolog family. pAd-SKIV2L2 was administrated after coronary artery ligation to investigate whether SKIV2L2 can provide a protective effect on the infarcted heart. Results: When both miR-155−/− and miR-155wt CFs were exposed to hypoxia for 24 h, these two cells exhibited an increased glycolysis and decreased glycogen synthesis, and the expression of KHK-A and KHK-C, the central fructose-metabolizing enzyme, was upregulated. Mechanistically, miR-155 deletion in CFs enhanced SKIV2L2 expression and its interaction with TRA2A, which suppresses the alternative splicing of HIF1α pre-mRNA to form circHIF1α, and then decreased circHIF1α contributed to the activation of fructose metabolism through increasing the production of the KHK-C isoform. Finally, exogenous delivery of SKIV2L2 reduced myocardial damage in the infarcted heart. Conclusion: In this study, we demonstrated that miR-155 deletion facilitates the activation of fructose metabolism in hypoxic CFs through regulating alternative splicing of HIF1α pre-mRNA and thus circHIF1ɑ formation.

[Display omitted] • miR-155 suppresses splicing factor SKIV2L2 expression by targeting it's 3′ UTR. • miR-155 deletion enhances SKIV2L2 expression and its interaction with TRA2A. • SKIV2L2/TRA2A complex suppresses alternative splicing of HIF1α pre-mRNA to form circHIF1α. • circHIF1α deletion contributes to fructose metabolism by increasing the production of KHK-C. • Exogenous delivery of SKIV2L2 reduces damage in the infarcted heart. • miR-155 downregulation protects the heart from hypoxic injury by activating fructose metabolism. Hypoxia-inducible factor (HIF)1α has been shown to be activated and induces a glycolytic shift under hypoxic condition, however, little attention was paid to the role of HIF1α-actuated fructolysis in hypoxia-induced heart injury. In this study, we aim to explore the molecular mechanisms of miR-155-mediated fructose metabolism in hypoxic cardiac fibroblasts (CFs). Immunostaining, western blot and quantitative real-time reverse transcription PCR (qRT-PCR) were performed to detect the expression of glucose transporter 5 (GLUT5), ketohexokinase (KHK)-A and KHK-C in miR-155−/− and miR-155wt CFs under normoxia or hypoxia. A microarray analysis of circRNAs was performed to identify circHIF1α. Then CoIP, RIP and mass spectrometry analysis were performed and identified SKIV2L2 (MTR4) and transformer 2 alpha (TRA2A), a member of the transformer 2 homolog family. pAd-SKIV2L2 was administrated after coronary artery ligation to investigate whether SKIV2L2 can provide a protective effect on the infarcted heart. When both miR-155−/− and miR-155wt CFs were exposed to hypoxia for 24 h, these two cells exhibited an increased glycolysis and decreased glycogen synthesis, and the expression of KHK-A and KHK-C, the central fructose-metabolizing enzyme, was upregulated. Mechanistically, miR-155 deletion in CFs enhanced SKIV2L2 expression and its interaction with TRA2A, which suppresses the alternative splicing of HIF1α pre-mRNA to form circHIF1α, and then decreased circHIF1α contributed to the activation of fructose metabolism through increasing the production of the KHK-C isoform. Finally, exogenous delivery of SKIV2L2 reduced myocardial damage in the infarcted heart. In this study, we demonstrated that miR-155 deletion facilitates the activation of fructose metabolism in hypoxic CFs through regulating alternative splicing of HIF1α pre-mRNA and thus circHIF1ɑ formation. [ABSTRACT FROM AUTHOR]