Constitutive expression of the S1P1 receptor in adult tissues.

S1P1 (also known as EDG-1) is a G-protein coupled receptor for the bioactive lipid, sphingosine-1-phosphate (S1P). Activation of S1P1 receptor in endothelial cells induces diverse cellular effects, including cell proliferation, survival, migration and morphogenesis. Recent in vivo studies showed that the S1P1 receptor is required in vascular maturation during development. While a number of studies reported a functional role of S1P1 in vascular system and the presence of S1P1 transcripts in various mouse organs, tissue distribution of S1P1 has not been fully defined. In this study, we determined the expression pattern of S1P1 by beta-galactosidase reporter gene expression, which is knocked into the S1P1 locus. We show that S1P1 is widely expressed in various cell types of adult mouse tissues, suggesting a regulatory role of this receptor in numerous physiological processes in both vascular and non-vascular tissues.