title: Redox regulation of human protease-activated receptor-2 by activated factor X.
abstract: Activated factor X (FXa) exerts coagulation-independent actions such as proliferation of vascular smooth muscle cells (SMCs) through the protease-activated receptors PAR-1 and PAR-2. Both receptors are upregulated upon vascular injury but the underlying mechanisms have not been defined. We examined if FXa regulates PAR-1 and PAR-2 in human vascular SMCs. FXa increased PAR-2 mRNA, protein, and cell-surface expression and augmented PAR-2-mediated mitogenesis. PAR-1 was not influenced. The regulatory action of FXa on PAR-2 was concentration-dependent and mimicked by a PAR-2-selective activating peptide. PAR-2 regulation was not influenced by the thrombin inhibitor argatroban or PAR-1 siRNA. FXa increased dichlorofluorescein diacetate fluorescence and 8-isoprostane formation and induced expression of the NADPH oxidase subunit NOX-1. NOX-1 siRNA prevented FXa-stimulated PAR-2 regulation, as did ebselen and cell-permeative and impermeative forms of catalase. Exogenous H(2)O(2) increased PAR-2 expression and mitogenic activity. FXa promoted nuclear translocation and PAR-2/DNA binding of nuclear factor κB (NF-κB); NF-κB inhibition prevented PAR-2 regulation by FXa. FXa also promoted PAR-2 mRNA stabilization through increased human antigen R (HuR)/PAR-2 mRNA binding and cytoplasmic shuttling. HuR siRNA abolished FXa-stimulated PAR-2 expression. Thus FXa induces functional expression of PAR-2 but not of PAR-1 in human SMCs, independent of thrombin formation, via a mechanism involving NOX-1-containing NADPH oxidase, H(2)O(2), NF-κB, and HuR.
authors.affiliation: Institut für Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Jobi
authors.forename: Bernhard H
authors.initials: BH
authors.lastname: Rauch
authors.forename: Seema
authors.initials: S
authors.lastname: Dangwal
authors.forename: Kerstin
authors.initials: K
authors.lastname: Freidel
authors.forename: Anke
authors.initials: A
authors.lastname: Doller
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Eberhardt
authors.forename: Jens W
authors.initials: JW
authors.lastname: Fischer
authors.forename: Karsten
authors.initials: K
authors.lastname: Schrör
authors.forename: Anke C
authors.initials: AC
authors.lastname: Rosenkranz
mesh_terms: D002478:Cells, Cultured; D015951:Factor Xa / Q000378:metabolism*; D006801:Humans; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044464:Receptor, PAR-2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D044464:Receptor, PAR-2; D015951:Factor Xa