Stress signaling of apoptosis via ceramide and c-jun kinase

Mammalian systems respond to environmental stress by either adapting for su rvival or undergoing programmed cell death (apoptosis). While it is general ly believed that the caspase family of proteases are essential effectors of the apoptotic response, much less is clear about the signaling machinery r equired to activate the caspase system in response to stress stimuli. In th e past few years, increasing evidence has linked the sphingomyelin and c-ju n kinase (JNK) pathways to the death response in various cellular systems. Both signaling pathways are evolutionarily conserved through yeast. Since y east does not undergo apoptosis, these pathways appear evolutionarily older than the caspase-mediated death programs. This paper reviews the role of s phingomyelin/ceramide and the JNK pathways in co-ordinating the signaling e vents lending to apoptosis.