IMMUNOCYTOCHEMICAL AND IN-SITU HYBRIDIZATION STUDIES OF THE HEPARAN-SULFATE PROTEOGLYCAN, GLYPICAN, IN NERVOUS-TISSUE

Using immunocytochemistry and in situ hybridization histochemistry, we have investigated in embryonic and postnatal rat nervous tissue the l ocalization and cellular sites of synthesis of glypican, a glycosylpho sphatidylinositol-anchored heparan sulfate proteoglycan. Glypican immu noreactivity is present in the marginal layer (prospective white matte r) and in the dorsal root entry zone of E13-16 spinal cord, as well as in the optic nerve and retina at this stage, but does not appear at s ignificant levels in brain until approximately E19. The proteoglycan s hows a wide distribution in grey matter and axonal projections of post natal brain, including the hippocampal formation, the parallel fibers of cerebellar granule cells, and in the medulla and brainstem, Norther n analysis demonstrated high levels of glypican mRNA in brain and skel etal muscle, and in rat PC12 pheochromocytoma cells. In situ hybridiza tion histochemistry showed that glypican mRNA was especially prominent in cerebellar granule cells, large motor neurons in the brainstem, an d CA3 pyramidal cells of the hippocampus. Our immunocytochemical and i n situ hybridization results indicate that glypican is predominantly a neuronal membrane proteoglycan in the late embryonic and postnatal ra t central nervous system.