title: Modulation of Rho GTPase activity in endothelial cells by selective proteinase-activated receptor (PAR) agonists.
abstract: The proteinase-activated receptors (PAR) PAR1 and PAR2 mediate responses to thrombin and trypsin-like proteases, respectively. Both receptors are expressed on endothelial cells where they have been reported to transduce a similar set of intracellular responses. In cultured human umbilical vein endothelial cells (HUVEC), we observed a marked difference in shape changes induced by PAR-activating peptides (PAR-APs); unlike PAR1-AP, PAR2-AP failed to stimulate cell rounding. Objectives were to shed light on the mechanisms underlying PAR-mediated cytoskeletal responses. We examined the activation of the Rho family GTPases in HUVEC using highly selective PAR1- and PAR2-APs to do this. Both peptides induced a robust and transient activation of RhoA, with the time course of activation being more sustained for the PAR1-AP. Interestingly, divergent effects on Rac activity were observed. Addition of PAR1-AP inhibited basal Rac activity as well as the phosphorylation of the Rac effector, p21-activated kinase (PAK). In contrast, PAR2-AP induced a modest activation of Rac, phosphorylation of PAK and translocation of cortactin from the cytosol to membrane ruffles, a Rac-dependent event. In vivo, only PAR1-AP rapidly enhanced vascular permeability in a mouse skin assay. We conclude that the differential regulation of the Rac/PAK pathway by PAR1 and PAR2 agonists in endothelial cells points toward distinct roles for these receptors in the control of vascular permeability and blood vessel remodeling.
authors.affiliation: Institute of Signaling, Developmental Biology and Cancer Research, CNRS UMR6543, Center Antoine Lacassagne, Nice, France.
authors.forename: V
authors.initials: V
authors.lastname: Vouret-Craviari
authors.forename: D
authors.initials: D
authors.lastname: Grall
authors.forename: E
authors.initials: E
authors.lastname: Van Obberghen-Schilling
mesh_terms: D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D044463:Receptor, PAR-1 / Q000819:agonists*; D044464:Receptor, PAR-2 / Q000819:agonists; D012867:Skin / Q000098:blood supply; D054462:p21-Activated Kinases; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000187:drug effects / Q000378:metabolism
chemical_list: D009842:Oligopeptides; C462999:PAR-1-activating peptide; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein