ROLE OF BASAL LAMINA IN SCHWANN-CELL GLYCOLIPID BIOSYNTHESIS

Schwann cells that are deprived of axonal contact switch their glycoli pid metabolic pathway from primarily galactocerebroside (GalCe) synthe sis to the formation of glucocerebroside (GlcCe) and its homologs. The removal of axonal influence has a dual effect on Schwann cell phenoty pe; they lose the ability to assemble both myelin and basement membran e. To determine whether a loss of basement membrane directly affects g lycolipid expression, we have examined lipid biosynthesis in Schwann c ells which were allowed to interact with axons of dorsal root ganglion neurons but which were deprived of the ability to assemble basal lami na. These Schwann cells resemble those from myelinating nerve in that they synthesize a large amount of galactohydroxycerebroside. This sugg ests that axon contact, even in the absence of basement membrane, is s ufficient to induce the GalCe metabolic pathway.