EXPRESSION OF A UNIQUE GLOBO-SERIES GLYCOLIPID IN CULTURED RAT DORSAL-ROOT GANGLION NEURONS - RELATIONSHIP WITH NEURONAL DEVELOPMENT

Previous studies from this laboratory demonstrated the presence of a U DP-galactose:Gb3Cer alpha 1-3galactosyltansferase activity responsible for the synthesis of a unique glycosphingolipid (GSL), Gal alpha 1-3G b3Cer, in cultured PC12 pheochromocytoma cells (21). In this investiga tion, we examined the presence of this enzyme activity in isolated rat embryonic dorsal root ganglion neurons (DRGN), which, like pheochromo cytoma cells, originate from the neural crest cells. DRGN exhibited th e oc-galactosyltransferase activity and the activity was comparable to that of the PC12 cells while several other rat tissues, with the exce ption of kidney, showed minimal activity. In order to define the spati al and temporal expression of Gal alpha 1-3Gb3Cer in DRGN, we examined the expression of Gal alpha 1-3Gb3Cer in cultured DRGN derived from e mbryonic day 16 rat embryos. Using a polyclonal antibody raised agains t Gal alpha 1-3Gb3Cer, we examined the localization of this glycolipid in DRGN cells after 5, 8, 12, and 15 days in culture. Immunostaining was restricted to the neurons while Schwann cells were negative. At da y 5, the immunostaining was weak and confined to the cell body of the DRGN, though neurites were present at this stage. The period between d ays 5 and 15 represented a period of rapid neuritic growth and continu ed enlargement of the cell bodies. Immunoreactivity in the cell bodies increased dramatically by day 8. By day 12, immunoreactivity was pres ent in neurites, and by day 15, was strong in both cell bodies and neu rites. The expression of Gal alpha 1-3Gb3Cer in vivo was confirmed by immunostaining of frozen sections of dorsal root ganglia. Our present studies which demonstrate neuron-specific expression of Gal alpha 1-3G b3Cer during neurotigenesis combined with previous observations for it s expression in PC12 cells, strongly implicates this GSL in neuronal d evelopment.