Sphingolipid metabolism in the regulation of bioactive molecules

In conclusion, the study of signaling and cell regulation through ceramide has now evolved to the biochemical level by focusing on specific enzymes of ceramide metabolism. A general hypothesis can be presented whereby individual enzymes of ceramide metabolism serve as input points in the regulation of ceramide levels (Scheme 1). For example, activation of SMases or ceramide synthase would elevate ceramide levels and activate ceramide-induced responses. On the other hand, activation of enzymes of ceramide degradation or incorporation such as ceramidases or SM synthase decreases and attenuates ceramide levels. Also, as an important corollary, some of these enzymes may play an additional fundamental role in interconverting lipid signals. For example, SM synthase has the capacity of interconverting a ceramide signal into a DAG signal, whereas ceramidases can transform a ceramide signal into a sphingosine or sphingosine-phosphate signal. This area of research promises great future insight into important areas of cell studies.