title: Targeted disruption of GAP-43 in P19 embryonal carcinoma cells inhibits neuronal differentiation. As well as acquisition of the morphological phenotype.
abstract: GAP-43 is expressed in proliferating neuroblasts in vivo and in vitro, but its role during early neurogenesis has not been investigated. Here we show that neuroectodermal differentiation stimulated by retinoic acid (RA) in the embryonal carcinoma (EC) line P19 is accompanied by upregulation of GAP-43 expression in neuroepithelial precursor cells. In contrast, when upregulation of GAP-43 expression was prevented in 3 independent P19 lines because of a targeted insertion into the gene, generation of neuroepithelial precursors was inhibited. Consequently, neuronal number was significantly decreased, neuronal morphology was abnormal and fewer than 20% of all neurons were able to initiate neuritogenesis. Extracellular matrix (ECM) was unable to rescue initiation of neuritogenesis in the mutant cells, however those neurites that were extended responded normally to ECM-stimulated neurite outgrowth-promoting signals. These data suggest that GAP-43 function is required for commitment to a neuronal phenotype as well as initiation of neurite extension. However, stimulation of neurite outgrowth by ECM in P19s occurs independently of GAP-43.
authors.affiliation: Departments of Pharmacology and Program in Neuroscience, SUNY Health Science Center, 750, East Adams Street, Syracuse, NY, USA.
authors.forename: S
authors.initials: S
authors.lastname: Mani
authors.forename: J
authors.initials: J
authors.lastname: Schaefer
authors.forename: K F
authors.initials: KF
authors.lastname: Meiri
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D003094:Collagen / Q000378:metabolism / Q000494:pharmacology; D004338:Drug Combinations; D054278:Embryonal Carcinoma Stem Cells; D005109:Extracellular Matrix / Q000378:metabolism; D019922:GAP-43 Protein / Q000096:biosynthesis / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018390:Gene Targeting; D006720:Homozygote; D007797:Laminin / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D018715:Microscopy, Video; D014411:Neoplastic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016501:Neurites / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000166:cytology*; D010641:Phenotype; D011509:Proteoglycans / Q000378:metabolism / Q000494:pharmacology; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D004338:Drug Combinations; D019922:GAP-43 Protein; D007797:Laminin; D011509:Proteoglycans; C059485:matrigel; D014212:Tretinoin; D003094:Collagen