SphK

Sphingosine kinase (SphK1 and SphK2) is a lipid enzyme that catalyses the phosphorylation of sphingosine to form sphingosine 1-phosphate (S1P). Two isoforms of SphK are found in mammalian organisms, SphK1 and SphK2. SphK1 is found primarily in the cytoplasm and the plasma membrane of erythrocyte, endothelial and mast cells. SphK2 is larger and localized to the endoplasmic reticulum, nucleus, and mitochondria.

S1P binds to five different plasma membrane sphingosine 1-phosphate receptors (S1P_1-5) and can regulate intracellular target proteins. S1P has a wide range of biological functions including promotion of cellular proliferation and survival, immune cell trafficking, stimulation of angiogenesis, and regulation of vascular integrity. Accumulation of S1P has been linked to the development/progression of cancer and various other diseases including, but not limited to, asthma, inflammatory bowel disease, rheumatoid arthritis, and diabetic nephropathy. Thus, the biosynthetic route to S1P is a logical target for drug discovery. SphK1 and SphK2 isozymes are also recognized therapeutic targets.