Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 108, Issue 50, Pages E1372-E1380Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1112482108
Keywords
biased agonism; endothelial dysfunction; inflammation; sepsis
Categories
Funding
- National Institutes of Health [HL073328]
- University of California [20FT-0074]
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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 beta-arrestin recruitment and activation of the dishevelled-2 (Dvl-2) scaffold and not by G protein alpha inhibiting activity polypeptide 2 (G alpha(i)) signaling. In human endothelial cells, PAR1 and beta-arrestins form a preassembled complex and cosegregate in caveolin-1-enriched fractions. Remarkably, we found that depletion of beta-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 beta-arrestin expression. We further demonstrate that APC activation of PAR1 results in beta-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 beta-arrestin and Dvl-2 scaffolds in APC-activated PAR1 cytoprotective signaling in human endothelial cells.
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