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  • Sphingosine-1-phosphate induces thrombin receptor PAR-4 expression to enhance cell migration and COX-2 formation in human monocytes.

Sphingosine-1-phosphate induces thrombin receptor PAR-4 expression to enhance cell migration and COX-2 formation in human monocytes.

Journal of leukocyte biology (2014-07-06)
Shailaja Mahajan-Thakur, Björn D Sostmann, Anke C Fender, Daniel Behrendt, Stephan B Felix, Karsten Schrör, Bernhard H Rauch
초록

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.

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Sigma-Aldrich
Prostaglandin E2, synthetic, powder, BioReagent, suitable for cell culture
Sigma-Aldrich
Prostaglandin E2, ≥93% (HPLC), synthetic
Sigma-Aldrich
Prostaglandin E2, γ-irradiated, powder, BioXtra, suitable for cell culture
Sigma-Aldrich
Sphingosine 1-phosphate, ≥98.0% (TLC)
Sigma-Aldrich
Anti-β-Actin antibody, Mouse monoclonal, clone AC-15, purified from hybridoma cell culture
Dinoprostone, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
Anti-PAR4 antibody produced in rabbit, affinity isolated antibody