Urtz, Nicole, Gaertner, Florian, von Bruehl, Marie-Luise , Chandraratne, Sue, Rahimi, Faridun, Zhang, Lin, Barocke, Verena, Beil, Johannes, Schubert, Irene, Lorenz, Michael, Legate, Kyle R. , Beerli, Christian, Ledieu, David, Persohn, Elke, Billich, Andreas, Baumruker, Thomas, Mederos y Schnitzler, Michael and Massberg, Steffen (2015) Sphingosine 1-phosphate produced by sphingosine kinase 2 intrinsically controls platelet aggregation in vitro and in vivo. Circulation Research, 117 (4). pp. 376-387. ISSN -

Abstract

Rationale:
Platelets are known to play a crucial role in hemostasis. Sphingosine kinases 1 and 2 (Sphk) catalyze the conversion of sphingosine (Sph) to the bioactive metabolite sphingosine 1-phosphate (S1P). Although platelets are able to secrete S1P upon activation, little is known about a potential intrinsic effect of S1P on platelet function.
Objective:
To investigate the role of Sphk1- and Sphk2-derived S1P in the regulation of platelet function.
Methods and Results:
We found a 100-fold reduction in intracellular S1P levels in platelets derived from Sphk2-/- mutants compared to Sphk1-/- or wildtype (WT) mice, as analyzed by mass spectrometry. Sphk2-/- platelets also failed to secrete S1P upon stimulation. Blood from Sphk2-deficient mice showed decreased aggregation after protease-activated receptor 4-peptide (PAR4-P) and adenosine-diphosphate (ADP) stimulation in vitro, as assessed by whole blood impedance aggregometry. We revealed that S1P controls platelet aggregation via the sphingosine 1-phosphate receptor 1 (S1PR1) through modulation of PAR4-P and ADP induced platelet activation. Finally, we show by intravital microscopy that defective platelet aggregation in Sphk2 deficient mice translates into reduced arterial thrombus stability in vivo.
Conclusions:
We demonstrate that Sphk2 is the major Sphk isoform responsible for the generation of S1P in platelets and plays a pivotal intrinsic role in the control of platelet activation. Correspondingly, Sphk2-deficient mice are protected from arterial thrombosis after vascular injury, but have normal bleeding times. Targeting this pathway could therefore present a new therapeutic strategy to prevent thrombosis.

Item Type:	Article
Keywords:	sphingosine kinase, sphingosine 1-phosphate, platelet aggregation, arterial thrombosis
Date Deposited:	12 Oct 2016 00:45
Last Modified:	12 Oct 2016 00:45
URI:	https://oak.novartis.com/id/eprint/26075