Review paper
Biological activity of ceramides and other sphingolipids

Sphingolipids are a large group of lipids which play a key role in the cellular life cycle. In addition to structural functions (they are constituents of cell membranes), they are known to be involved in processes of intercellular recognition and signal transmission. Ceramides, which are sphingolipid metabolites, take part in signal transduction and initiation of a range of processes which affect the cell life. Depending on the external stimulus and cell type, the processes may include inhibition of proliferation, initiation of differentiation or apoptosis. For example, studies have shown that an increased concentration of endogenous ceramides caused by activation of the membrane receptor CD95 activates a number of processes triggering programmed cell death. At the same time, study results have demonstrated that due to their specific structure ceramides are able to interact directly with a number of key enzymes and activate them. What is more, not only endogenous ceramides have the capacity to elicit a specific biological response. Exogenous ceramides and their structural analogues are also able to affect the cellular life cycle, which makes them potentially therapeutic substances.