Tissue expression and biological functions of
GalCer
GalCer has been originally described in
the central nervous system. It is expressed in glial cells (i.e.
oligodendrocytes and Schwann cells, respectively in the central and peripheric
nervous systems) and it is the major lipid component of myelin, the protective
sheath of axons that insulate the axon from electrical activity. This
insulation is necessary to increase the rate of transmission of neuronal
signals.
GalCer is also one of the major
glycosphingolipids expressed by intestinal epithelial cells, which are involved
in the terminal hydrolysis and uptake of nutrients.
Lipid rafts have been involved in the
regulation of cellular communication pathways (signal transduction). Indeed,
stimulation of GalCer at the surface of both neural and intestinal cells
results in a rise of intracellular calcium concentration (9).