Apolipoprotein E Receptor 2 Mediates Activated Protein C–Induced Endothelial Akt Activation and Endothelial Barrier Stabilization. Issue 3 (March 2016)

• Record Type: Journal Article
• Authors: Sinha, Ranjeet K.; Yang, Xia V.; Fernández, José A.; Xu, Xiao; Mosnier, Laurent O.; Griffin, John H.
• Is Part Of: Arteriosclerosis, thrombosis, and vascular biology. Volume 36:Issue 3(2016)
• Publication Date: 2016-03
• Subjects: apolipoprotein E receptor 2 -- apoptosis -- endothelial cells -- low density lipoprotein receptor-related protein 8 -- protein C -- signal transduction; Arteriosclerosis -- Periodicals; Thrombosis -- Periodicals; Blood-vessels -- Pathophysiology -- Periodicals; Electronic journals; 616.13
• DOI: 10.1161/ATVBAHA.115.306795
• Languages: English
• ISSNs: 1079-5642

Abstract

Abstract : Objective—: Activated protein C (APC), a plasma serine protease, initiates cell signaling that protects endothelial cells from apoptosis and endothelial barrier disruption. Apolipoprotein E receptor 2 (ApoER2; LRP8 ) is a receptor known for mediating signaling initiated by reelin in neurons. ApoER2 contributes to APC-initiated signaling in monocytic U937 cells. The objective was to determine whether ApoER2 is required for APC's beneficial signaling in the endothelial cell surrogate EA.hy926 line. Approach and Results—: We used small interfering RNA and inhibitors to probe requirements for specific receptors for APC's antiapoptotic activity and for phosphorylation of disabled-1 by Src family kinases and of Akt. When small interfering RNA for ApoER2 or endothelial cell protein C receptor or protease activated receptor 1 was used, APC's antiapoptotic activity was ablated, indicating that each of these receptors was required. In EA.hy926 cells, APC induced a 2- to 3-fold increased phosphorylation of Ser473-Akt and Tyr232-disabled-1, a phosphorylation known to trigger disabled-1–mediated signaling in other cell types. Ser473-Akt phosphorylation was inhibited by ApoER2 small interfering RNA or by inhibitors of Src (PP2), phosphatidylinositol-3 kinase (LY303511), and protease activated receptor 1 (SCH79797). ApoER2 small interfering RNA blocked the ability of APC to prevent thrombin-induced endothelial barrier disruption in TransEndothelial Resistance assays. Binding studies using purified APC and purified immobilized wild-type and mutated ApoER2 ectodomains suggested that APC binding involves Lys49, Asp50, and Trp64 on the surface of the N-terminal LA1 domain of ApoER2. Conclusions—: ApoER2 contributes cooperatively with endothelial cell protein C receptor and protease activated receptor 1 to APC-initiated endothelial antiapoptotic and barrier protective signaling. Abstract : Supplemental Digital Content is available in the text.