Sphingosine and ceramide signalling in apoptosis.

The sphingomyelin pathway is activated in response to many apoptotic stimuli leading to the accumulation of breakdown products ceramide and sphingosine. Ceramide has received much attention as an apoptotic second messenger whereas sphingosine has largely been overlooked as a mediator of apoptosis. Recent studies however provide strong clues to a second messenger role for sphingosine and identification of effectors reveal a possible mechanism involved in sphingosine-mediated cell death. This mini-review overviews the current knowledge of the role of ceramide and sphingosine in apoptosis and discusses their biological effects. The review attempts to reconcile the apoptotic effects of these lipids with the downstream effectors that have been identified.