Sphingosine-1-phosphate: signaling inside and out

Ample evidence indicates that sphingosine-1-phosphate (SPP) can serve as an intracellular second messenger regulating calcium mobilization, and cell g rowth and survival. Moreover, the dynamic balance between levels of the sph ingolipid metabolites, ceramide and SPP, and consequent regulation of oppos ing signaling pathways, is an important factor that determines whether a ce ll survives or dies. SPP has recently also been shown to be the ligand for the EDG-1 family of G-protein-coupled receptors, which now includes EDG-1, -3, -5, -6 and -8, SPP is thus a lipid mediator that has novel dual actions signaling inside and outside of the cell. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserv ed.