Sphingosine 1-phosphate stimulates cell migration through a G(i)-coupled cell surface receptor - Potential involvement in angiogenesis

Sphingosine l-phosphate (SPP) has been shown to inhibit chemotaxis of a var iety of cells, in some cases through intracellular actions, while in others through receptor-mediated effects. Surprisingly, we found that low concent rations of SPP (10-100 nm) increased chemotaxis of HEK293 cells overexpress ing the G protein-coupled SPP receptor EDG-1. In agreement with previous fi ndings in human breast cancer cells (Wang, F., Nohara, K., Olivera, O., Tho mpson, E. W., and Spiegel, S. (1999) Exp. Cell Res. 247, 17-28), SPP, at mi cromolar concentrations, inhibited chemotaxis of both vector- and EDG-1-ove rexpressing HEK293 cells. Nanomolar concentrations of SPP also induced a ma rked increase in chemotaxis of human umbilical vein endothelial cells (HUVE C) and bovine aortic endothelial cells (BAEC), which express the SPP recept ors EDG-1 and EDG-3, while higher concentrations of SPP were less effective . Treatment with pertussis toxin, which ADP-ribosylates and inactivates G(i )-coupled receptors, blocked SPP-induced chemotaxis. Checkerboard analysis indicated that SPP stimulates both chemotaxis and chemokinesis. Taken toget her, these data suggest that SPP stimulates cell migration by binding to ED G-1. Similar to SPP, sph-inganine 1-phosphate (dihydro-SPP), which also bin ds to this family of SPP receptors, enhanced chemotaxis; whereas, another s tructurally related lysophospholipid, lysophosphatidic acid, did not compet e with SPP for binding nor did it have significant effects on chemotaxis of endothelial cells. Furthermore, SPP increased proliferation of HUVEC and B AEC in a pertussis toxin-sensitive manner. SPP and dihydro-SPP also stimula ted tube formation of BAEC grown on collagen gels (in vitro angiogenesis), and potentiated tube formation induced by basic fibroblast growth factor. P ertussis toxin treatment blocked SPP-, but not bFGF-stimulated in vitro ang iogenesis. Our results suggest that SPP may play a role in angiogenesis thr ough binding to endothelial cell Gi-coupled SPP receptors.