The role of sphingomyelin cycle metabolites in transmission of signals of cell proliferation, differentiation and death

Metabolites of sphingomyelin cycle - ceramide, sphingosine and sphingosine- 1-phosphate play an important role in cell proliferation, differentiation, reception, oncogenesis and apoptosis. Ceramide is intracellular second mess enger for apoptosis activating proteases and specific phosphatases. Sphingo sine is endogenous inhibitor of protein kinase C and influences as an inhib itor at many cell functions depending on the activity of this enzyme. On th e other hand, sphingosine can activate other kinases depending on the conce ntration, the cell type and the nature of the stimulus and release Ca2+ fro m intracellular stores thereby regulating cell proliferation. Sphingosine i nduces apoptosis and its level is increased in cells as a result of action of apoptotic inducers. Phosphorylated product of sphingosine - sphingosine-1-phosphate mediates mi togenic signal, induces Ca2+ mobilization and protects cells from apoptosis resulting from elevations of ceramide: The quantitative levels of sphingom yelin metabolites in cell determine the dynamic balance between apoptotic a nd mitogenic signals.