title: Activated protein C promotes protease-activated receptor-1 cytoprotective signaling through β-arrestin and dishevelled-2 scaffolds.
abstract: Protease-activated receptor-1 (PAR1) is a guanine nucleotide-binding (G) protein-coupled receptor that elicits cellular responses to coagulant and anticoagulant proteases. Activation of PAR1 by the coagulant protease thrombin results in Ras homolog gene family member A (RhoA) activation, disassembly of adherens junctions, and disruption of the endothelial barrier. In contrast, activation of PAR1 with the anticoagulant protease activated protein C (APC) results in activation of Ras-related C3 botulinum toxin substrate 1 (Rac1) and endothelial barrier protection. We previously showed that APC cytoprotective signaling requires the compartmentalization of PAR1 in caveolar microdomains. However, the mechanism by which APC-activated PAR1 promotes cytoprotective signaling in human endothelial cells remains poorly understood. Here we show that APC-activated PAR1 cytoprotective signaling is mediated by β-arrestin recruitment and activation of the dishevelled-2 (Dvl-2) scaffold and not by G protein α inhibiting activity polypeptide 2 (Gα(i)) signaling. In human endothelial cells, PAR1 and β-arrestins form a preassembled complex and cosegregate in caveolin-1-enriched fractions. Remarkably, we found that depletion of β-arrestin expression by RNA interference resulted in the loss of APC-induced Rac1 activation but not of thrombin-stimulated RhoA signaling. APC also failed to protect against thrombin-induced endothelial barrier permeability in cells deficient in β-arrestin expression. We further demonstrate that APC activation of PAR1 results in β-arrestin-dependent recruitment of Dvl-2, which is critical for Rac1 signaling and endothelial barrier protection but not for thrombin-induced RhoA signaling. Our findings identify a role for β-arrestin and Dvl-2 scaffolds in APC-activated PAR1 cytoprotective signaling in human endothelial cells.
authors: Department of Pharmacology, School of Medicine, University of California at San Diego, La Jolla, CA 92093, USA.
authors: Unice J K
authors: UJ
authors: Soh
authors: JoAnn
authors: J
authors: Trejo
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D019390:Arrestins / Q000378:metabolism*; D051242:Caveolin 1 / Q000378:metabolism; D019610:Cytoprotection; D000072261:Dishevelled Proteins; D042783:Endothelial Cells / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D058105:Polymerization; D011485:Protein Binding; D011486:Protein C / Q000378:metabolism*; D021381:Protein Transport; D044463:Receptor, PAR-1 / Q000378:metabolism*; D015398:Signal Transduction; D000071557:beta-Arrestins; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D019390:Arrestins; D051242:Caveolin 1; C000606581:DVL2 protein, human; D000072261:Dishevelled Proteins; D010750:Phosphoproteins; D011486:Protein C; D044463:Receptor, PAR-1; D000071557:beta-Arrestins; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020830:rac1 GTP-Binding Protein