Membrane dynamics and cell polarity: the role of sphingolipids.

In recent years, glycosphingolipids (GSLs) have attracted widespread attention due to the appreciation that this class of lipids has a major impact on biological life. Inhibition of the synthesis of glucosylceramide, which serves as a precursor for the generation of complex glycosphinglipids, is embryonic lethal. GSLs play a major role in growth and development. Metabolites of sphingolipids, such as ceramide, sphinganine, and sphingosine, may function as second messengers or regulators of signal transduction that affect events ranging from apoptosis to the (co)regulation of the cell cycle. In addition, GSLs can provide a molecular platform for clustering of signal transducers. The ability of sphingolipids, with or without cholesterol, to form microdomains or rafts is critical in sorting and membrane transport that underlies the biogenesis of polarized membrane domains. Here, a brief summary is presented of some recent developments in this field, with a particular emphasis on raft assembly and membrane transport in the establishment of membrane polarity.