Module 2: Figure sphingomyelin signalling
The sphingomyelin signalling pathway.
A number of stimuli can activate the neutral or acidic sphingomyelinases (SMase) to hydrolyse sphingomyelin (SM) to ceramide (Cer), which is then converted into sphingosine (Sph) by ceramidase (CDase). The sphingosine is converted into sphingosine 1-phosphate (S1P) by a sphingosine kinase (SPHK), which is sensitive to other signalling pathways using messengers such as Ca2+, diacylglycerol (DAG), cyclic AMP (cAMP) and extracellular-signal-regulated kinase 1/2 (ERK1/2). Ceramide can activate a number of targets, and some of these can activate apoptosis. On the other hand, S1P can promote survival and proliferation by passing out of the cell, where it functions as an external ligand to activate endothelial differentiation gene (EDG) receptors.