Neurite outgrowth in response to transfected N-CAM changes during development and is modulated by polysialic acid.
We have used monolayers of control 3T3 cells and 3T3 cells transfected with a cDNA encoding human N-CAM as a culture substrate for embryonic chick retinal ganglion cells (RGCs). At embryonic day 6 (E6), but not at E11, RGCs extended longer neurites on monolayers of N-CAM-transfected cells. This loss of RGC responsiveness was not associated with substantial changes in the level of N-CAM expression on RGC growth cones. The neurite outgrowth response from E6 RGCs could be inhibited by removal of N-CAM from the monolayer, by removal of alpha 2-8-linked polysialic acid from neuronal N-CAM, or by antibodies that bind exclusively to chick (neuronal) N-CAM. In contrast, the response was not dependent on neuronal beta 1 integrin function. These data provide substantive evidence for a homophilic binding mechanism directly mediating N-CAM-dependent neurite outgrowth, and suggest that changes in polysialic acid expression on neuronal N-CAM may modulate N-CAM-dependent axonal growth during development.
Department of Experimental Pathology, UMDS, Guy's Hospital, London, England.
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Doherty
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Cohen
F S
FS
Walsh
D000818:Animals; D000911:Antibodies, Monoclonal; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure*; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002642:Chick Embryo; D015536:Down-Regulation; D005455:Fluorescent Antibody Technique; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D010716:Phosphatidylinositols / Q000378:metabolism; D051381:Rats; D012160:Retina / Q000648:ultrastructure*; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure*; D012794:Sialic Acids / Q000378:metabolism*; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism
D000911:Antibodies, Monoclonal; D015816:Cell Adhesion Molecules, Neuronal; D010716:Phosphatidylinositols; D012794:Sialic Acids; C021319:polysialic acid; D006493:Heparin; D010738:Type C Phospholipases