title: Sphingosine-1-phosphate induces thrombin receptor PAR-4 expression to enhance cell migration and COX-2 formation in human monocytes.
abstract: Thrombin is not only a central factor in blood coagulation but also stimulates inflammatory processes, including monocyte responses, via activation of PARs. The signaling lipid S1P is a major determinant of monocyte function. Here, we established an interaction between S1P and human monocyte responses to thrombin. S1P induced PAR-1 and PAR-4 mRNA and total protein expression in human monocytes and U937 cells in a concentration (0.1-10 μM)- and time (1-24 h)-dependent manner, respectively. However, only PAR-4 cell-surface expression was increased significantly by S1P, whereas PAR-1 remained unaffected. This response was associated with activation of the Akt, Erk, and p38 pathway and induction of COX-2 but not COX-1. PAR-4-mediated induction of COX-2 was prevented by the PI3K inhibitor LY (10 μM). Preincubation of human monocytes with S1P (1 μM; 16 h) resulted in an enhanced chemotaxis toward thrombin or to selective AP for PAR-4 but not PAR-1. Furthermore, down-regulation of PAR-4 transcription with siRNA attenuated the chemotactic response to thrombin and AP4. In conclusion, S1P enhances monocyte responses to thrombin via up-regulation of PAR-4 expression, which promotes cell migration and COX-2 abundance. This mechanism may facilitate monocyte recruitment to sites of vessel injury and inflammation.
authors.affiliation: Institut für Pharmakologie, Center of Drug Absorption and Transport.
authors.forename: Shailaja
authors.initials: S
authors.lastname: Mahajan-Thakur
authors.affiliation: Institut für Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: Björn D
authors.initials: BD
authors.lastname: Sostmann
authors.affiliation: Institut für Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: Anke C
authors.initials: AC
authors.lastname: Fender
authors.affiliation: Klinik und Poliklinik für Chirurgie, Abteilung für Allgemeine Chirurgie, Viszeral-, Thorax- und Gefässchirurgie, and.
authors.forename: Daniel
authors.initials: D
authors.lastname: Behrendt
authors.affiliation: Klinik und Poliklinik für Innere Medizin B, Universitätsmedizin Greifswald, Germany; and.
authors.forename: Stephan B
authors.initials: SB
authors.lastname: Felix
authors.affiliation: Institut für Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Schrör
authors.affiliation: Institut für Pharmakologie, Center of Drug Absorption and Transport, bernhard.rauch@uni-greifswald.de.
authors.forename: Bernhard H
authors.initials: BH
authors.lastname: Rauch
mesh_terms: D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects* / Q000235:genetics; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D015232:Dinoprostone / Q000096:biosynthesis; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology*; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D044463:Receptor, PAR-1 / Q000235:genetics / Q000378:metabolism; D018179:Receptors, Thrombin / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013917:Thrombin / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D008246:Lysophospholipids; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; C060506:sphingosine 1-phosphate; D051546:Cyclooxygenase 2; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D013917:Thrombin; C112908:protease-activated receptor 4; D015232:Dinoprostone; D013110:Sphingosine
keywords: cyclooxygenase-2; monocytes; protease-activated receptors