title: Distribution of the novel developmentally-regulated protein EAP-300 in the embryonic chick nervous system.
abstract: In a previous study we described a 300 kDa, developmentally regulated protein identified in embryonic chick neural retina with a monoclonal antibody. Because this protein has been shown to be undetectable in the adult nervous system, and the monoclonal antibody is species-specific, the protein has been named embryonal avian polypeptide of 300 kDa (EAP-300). In the present study we have analyzed the histological expression of EAP-300 during chick embryogenesis. In the developing nervous system, EAP-300 expression was detected as early as Stage 5 (19 h), and was subsequently down-regulated to undetectable levels in the adult. Of particular interest was the association of EAP-300 with putative barriers of neuronal growth, such as the telencephalon/diencephalon glial knot, the dorsal midline in the mesencephalon and the midline in myelencephalon, and the spinal cord roof plate. EAP-300 was also shown to be expressed by Bergmann glia during the period of granule cell migration in the cerebellum. The expression of EAP-300 by radial astrocytes was confirmed in culture by immunofluorescent co-labeling with a MAb to EAP-300 and the R5 MAb, which is a radial astrocyte-specific marker. It has also been shown that EAP-300, when immunopurified from embryonic brain under non-dissociating conditions, co-purifies with a neural keratan sulfate proteoglycan that is also associated with CNS barrier structures during brain development. The restricted expression of EAP-300 in nervous tissue, particularly in CNS barrier structures, suggests that EAP-300 may play an important, but transient, role in the development of the chick nervous system.
authors.affiliation: Department of Anatomy and Cell Biology, Medical University of South Carolina, Charleston 29425.
authors.forename: C F
authors.initials: CF
authors.lastname: McCabe
authors.forename: R P
authors.initials: RP
authors.lastname: Thompson
authors.forename: G J
authors.initials: GJ
authors.lastname: Cole
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000196:embryology; D001923:Brain Chemistry / Q000502:physiology; D002478:Cells, Cultured; D002490:Central Nervous System / Q000737:chemistry / Q000196:embryology*; D002531:Cerebellum / Q000737:chemistry; D002642:Chick Embryo; D011508:Chondroitin Sulfate Proteoglycans / Q000032:analysis*; D007124:Immunoenzyme Techniques; D007632:Keratan Sulfate / Q000032:analysis*; D000071234:Lumican; D008970:Molecular Weight; D009457:Neuroglia / Q000737:chemistry; D009479:Neuropeptides / Q000032:analysis*; D013116:Spinal Cord / Q000737:chemistry / Q000196:embryology
chemical_list: D011508:Chondroitin Sulfate Proteoglycans; D000071234:Lumican; D009479:Neuropeptides; D007632:Keratan Sulfate