Pleiotropic actions of sphingosine-1-phosphate.

Sphingosine-1-phosphate (SIP) is a bioactive sphingolipid metabolite that regulates diverse cellular responses including, growth, survival, cytoskeleton rearrangements and movement. SIP plays an important role during development, particularly in vascular maturation and has been implicated in pathophysiology of cancer, wound healing, and atherosclerosis. This review summarizes the evidence showing that signaling induced by SIP is complex and involves both intracellular and extracellular actions. The intracellular effects of SIP remain speculative awaiting the identification of specific targets whereas the extracellular effects of SIP are clearly mediated through the activation of five specific G protein coupled receptors, called S1P1-5. Recent studies demonstrate that intracellular generated SIP can act in a paracrine or autocrine manner to activate its cell surface receptors.