title: GAP-43 distribution is correlated with development of growth cones and presynaptic terminals.
abstract: GAP-43 (F1, B-50, pp46) has been associated with neuronal development and regeneration, but precise localization within neurons is not known. Pre-embedding electron microscopic immunocytochemistry using silver-enhanced 1 nm gold particles was used to localize GAP-43 label in cell cultures of cerebellar neurons. In the plasma membranes of early cultures, high levels of GAP-43 were seen in all parts of the neuron. In older cultures, consistent with previous reports, the first loss of GAP-43 label was seen in the soma and then the axon. Growth cones had high levels of GAP-43 label on the plasma membrane, with increased distribution over unattached relative to attached filopodia. The amount of GAP-43 seen over the plasma membrane of forming presynaptic terminals is lower than over growth cones, indicating a possible correlation between the presence of GAP-43 and the stage of presynaptic terminal development. Intracellular GAP-43 in axons and growth cones was highest in membranes of smooth cisternae. The levels of GAP-43 in smooth cisternae in axons fell by seven days in culture while the levels of GAP-43 in smooth cisternae of growth cones fell at 14 days. When mini-explant cerebellar cultures were examined with light microscopic immunocytochemistry, GAP-43 label of plasma membrane was highest at the periphery of the radial axonal outgrowth, suggesting that addition of GAP-43 to the plasma membrane can occur in the distal axon or at the growth cone.
authors.affiliation: Department of Cell Biology, Neurobiology and Anatomy, Ohio State University, Columbus 43210-1239.
authors.forename: R W
authors.initials: RW
authors.lastname: Burry
authors.forename: J J
authors.initials: JJ
authors.lastname: Lah
authors.forename: D M
authors.initials: DM
authors.lastname: Hayes
mesh_terms: D000818:Animals; D001369:Axons / Q000737:chemistry* / Q000648:ultrastructure; D015415:Biomarkers; D002478:Cells, Cultured; D002525:Cerebellar Cortex / Q000166:cytology; D019922:GAP-43 Protein; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000032:analysis*; D016253:Microscopy, Immunoelectron; D009411:Nerve Endings / Q000737:chemistry* / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000032:analysis*; D051381:Rats; D015398:Signal Transduction
chemical_list: D015415:Biomarkers; D019922:GAP-43 Protein; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins