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EphA2 activation promotes the endothelial cell inflammatory response: a potential role in atherosclerosis.

ABSTRACT: Endothelial cell activation results in altered cell-cell interactions with adjacent endothelial cells and with infiltrating leukocytes. Eph receptors and their ephrin ligands regulate cell-cell interactions during tissue remodeling, and multiple proinflammatory mediators induce endothelial EphA receptor and ephrinA ligand expression. Therefore, we sought to elucidate the role of EphA receptors and ephrinA ligands in endothelial cell activation and atherosclerosis.Quantitative reverse transcription-polymerase chain reaction screening for EphA/ephrinA expression in atherosclerosis-prone macrovascular endothelium identified EphA2, EphA4, and ephrinA1 as the dominant isoforms. Endothelial activation with oxidized low-density lipoprotein and proinflammatory cytokines induced EphA2 and ephrinA1 expression and sustained EphA2 activation, whereas EphA4 expression was unaffected. Atherosclerotic plaques from mice and humans showed enhanced EphA2 and ephrinA1 expression colocalizing in the endothelial cell layer. EphA2 activation with recombinant Fc-ephrinA1 induced proinflammatory gene expression (eg vascular cell adhesion molecule-1, E-selectin) and stimulated monocyte adhesion, whereas inhibiting EphA2 (small interfering RNA, pharmacological inhibitors) abrogated both ephrinA1-induced and oxidized low-density lipoprotein-induced vascular cell adhesion molecule-1 expression.The current data suggest that enhanced EphA2 signaling during endothelial cell activation perpetuates proinflammatory gene expression. Coupled with EphA2 expression in mouse and human atherosclerotic plaques, these data implicate EphA2 as a novel proinflammatory mediator and potential regulator of atherosclerotic plaque development.

SUBMITTER: Funk SD

PROVIDER: S-EPMC3325141 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature

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EphA2 activation promotes the endothelial cell inflammatory response: a potential role in atherosclerosis.

Funk Steven Daniel SD Yurdagul Arif A Albert Patrick P Traylor James G JG Jin Long L Chen Jin J Orr A Wayne AW

Arteriosclerosis, thrombosis, and vascular biology 20120112 3

<h4>Objective</h4>Endothelial cell activation results in altered cell-cell interactions with adjacent endothelial cells and with infiltrating leukocytes. Eph receptors and their ephrin ligands regulate cell-cell interactions during tissue remodeling, and multiple proinflammatory mediators induce endothelial EphA receptor and ephrinA ligand expression. Therefore, we sought to elucidate the role of EphA receptors and ephrinA ligands in endothelial cell activation and atherosclerosis.<h4>Methods an ...[more]

PMID: 22247258

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Project description:Atherosclerosis is the leading cause of death from vascular diseases worldwide, and endothelial cell (EC) dysfunction is the key cause of atherosclerosis. miR-155 was found to induce endothelial injury and to trigger atherosclerosis. In addition, brain and muscle ARNT-like protein-1 (Bmal1) has been found to be closely related to EC function. Therefore, the present study aimed to explore the mechanism underlying the regulation of Bmal1 by miR-155 in the induction of EC apoptosis and inflammatory response in atherosclerosis. The atherosclerosis model in apolipoprotein E (ApoE)- / - mice was established. miR-155 and Bmal1 expression was quantified by RT-qPCR and western blot analysis, respectively. The role of miR-155 and Bmal1 in atherosclerosis was evaluated through changes in cardiac function, plaque area, cardiomyocyte apoptosis, and inflammatory factor levels in mice. Moreover, the regulatory relationship between them was identified by dual-luciferase reporter gene assay to explore the mechanism of action of miR-155. After the modeling, the expression of miR-155 was upregulated and Bmal1 was downregulated in aorta, and there was a significant linear correlation between them. Upregulation of miR-155 increased the atherosclerotic plaque area, cell apoptosis, total cholesterol (TC) and triglyceride (TG), as well as weakened aortic diastolic function. However, opposite changes occurred after downregulation of miR-155 or an increase in Bmal1. In addition, the microRNA.org website predicted that there were targeted binding sites between miR-155 and Bmal1, which was verified with a dual-luciferase reporter gene assay. miR-155 was able to inhibit the expression by targeting Bmal1. Moreover, a rescue experiment showed that Bmal1 hindered the promotion of miR-155 in regards to atherosclerosis. In conclusion, miR-155 induces EC apoptosis and inflammatory response, weakens aortic diastolic function, and promotes the progression of atherosclerosis through targeted inhibition of Bmal1.

Project description:BackgroundNumerous genome-wide association studies revealed that SNPs (single nucleotide polymorphisms) at the PHACTR1 (phosphatase and actin regulator 1) locus strongly correlate with coronary artery disease. However, the biological function of PHACTR1 remains poorly understood. Here, we identified the proatherosclerotic effect of endothelial PHACTR1, contrary to macrophage PHACTR1.MethodsWe generated global (Phactr1-/-) and endothelial cell (EC)-specific (Phactr1ECKO) Phactr1 KO (knockout) mice and crossed these mice with apolipoprotein E-deficient (Apoe-/-) mice. Atherosclerosis was induced by feeding the high-fat/high-cholesterol diet for 12 weeks or partially ligating carotid arteries combined with a 2-week high-fat/high-cholesterol diet. PHACTR1 localization was identified by immunostaining of overexpressed PHACTR1 in human umbilical vein ECs exposed to different types of flow. The molecular function of endothelial PHACTR1 was explored by RNA sequencing using EC-enriched mRNA from global or EC-specific Phactr1 KO mice. Endothelial activation was evaluated in human umbilical vein ECs transfected with siRNA targeting PHACTR1 and in Phactr1ECKO mice after partial carotid ligation.ResultsGlobal or EC-specific Phactr1 deficiency significantly inhibited atherosclerosis in regions of disturbed flow. PHACTR1 was enriched in ECs and located in the nucleus of disturbed flow areas but shuttled to cytoplasm under laminar flow in vitro. RNA sequencing showed that endothelial Phactr1 depletion affected vascular function, and PPARγ (peroxisome proliferator-activated receptor gamma) was the top transcription factor regulating differentially expressed genes. PHACTR1 functioned as a PPARγ transcriptional corepressor by binding to PPARγ through the corepressor motifs. PPARγ activation protects against atherosclerosis by inhibiting endothelial activation. Consistently, PHACTR1 deficiency remarkably reduced endothelial activation induced by disturbed flow in vivo and in vitro. PPARγ antagonist GW9662 abolished the protective effects of Phactr1 KO on EC activation and atherosclerosis in vivo.ConclusionsOur results identified endothelial PHACTR1 as a novel PPARγ corepressor to promote atherosclerosis in disturbed flow regions. Endothelial PHACTR1 is a potential therapeutic target for atherosclerosis treatment.

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EphA2 activation promotes the endothelial cell inflammatory response: a potential role in atherosclerosis.

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EphA2 activation promotes the endothelial cell inflammatory response: a potential role in atherosclerosis.

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