Induction of vascular permeability by the sphingosine-1-phosphate receptor-2 (S1P2R) and its downstream effectors ROCK and PTEN.

OBJECTIVES: S1P acts via the S1PR family of G protein-coupled receptors to regulate a variety of physiological responses. Whereas S1P1R activates G(i)- and PI-3-kinase-dependent signals to inhibit vascular permeability, the related S1P2R inhibits the PI-3-kinase pathway by coupling to the Rho-dependent activation of the PTEN phosphatase. However, cellular consequences of S1P2R signaling in the vascular cells are not well understood.

METHODS AND RESULTS: Selective signaling of the S1P2R was achieved by adenoviral-mediated expression in endothelial cells. Secondly, endogenously expressed S1P2R was blocked by the specific pharmacological antagonist JTE013. Activation of S1P2R in endothelial cells resulted in Rho-ROCK- and PTEN-dependent disruption of adherens junctions, stimulation of stress fibers, and increased paracellular permeability. JTE013 treatment of naive endothelial cells potentiated the S1P1R-dependent effects such as formation of cortical actin, blockade of stress fibers, stimulation of adherens junction assembly, and improved barrier integrity. This observation was extended to the in vivo model of vascular permeability in the rat lung: the S1P2R antagonist JTE013 significantly inhibited H2O2-induced permeability in the rat lung perfused model.

CONCLUSIONS: S1P2R activation in endothelial cells increases vascular permeability. The balance of S1P1 and S1P2 receptors in the endothelium may determine the regulation of vascular permeability by S1P.