Participation of galactosylceramide and sulfatide in glycosynapses between oligodendrocyte or myelin membranes

The two major glycosphingolipids of myelin, galactosylceramide (GalC) and sulfatide (SGC), interact with each other by trans carbohydrate–carbohydrate interactions. They face each other in the apposed extracellular surfaces of the multilayered myelin sheath produced by oligodendrocytes (OLs). Multivalent galactose and sulfated galactose, in the form of GalC/SGC-containing liposomes or silica nanoparticles conjugated to galactose and galactose-3-sulfate, interact with GalC and SGC in the membrane sheets of OLs in culture. This stimulus results in transmembrane signaling, loss of the cytoskeleton and clustering of membrane domains, suggesting that GalC and SGC could participate in glycosynapses between apposed OL membranes or extracellular surfaces of mature myelin. Such glycosynapses may be important for myelination and/or myelin function.