Signal transduction and the regulation of apoptosis: roles of ceramide

Knowledge about the molecular regulators of apoptosis is rapidly expanding. Cell death signals emanating from death receptors or internal cell injury detectors launch a number of signaling pathways which converge on several key families of proteins including specialized proteases and endonucleases which play a critical role in the execution of the death order. In this review, we summarize recent discoveries relating to the signaling pathways involved, the death receptors, the caspase family of apoptotic proteases, Bcl-2 family members, the sphingolipid ceramide, and the tumor suppressor p53. In particular, we focus on the role played by ceramide as a coordinator of the stress response and as a candidate biostat in the detection of cell injury.