title: Patterning of motor neurons by retinoic acid in the chick embryo hindbrain in vitro.
abstract: Motor neurons are found throughout the developing chick hindbrain, while somatic motor (SM) neurons develop only in rhombomeres 5 to 8 (r5-8), and in r1. In r2-8 neuroepithelial explants from stage 7-10 embryos cultured in collagen gels, we found that motor neurons were generated throughout r2-8, while SM neuron differentiation was restricted to r5-8, as in vivo. Exposure of such explants to retinoic acid (RA) resulted in SM neuron differentiation throughout r2-8, while inclusion of the mesoderm and endoderm suppressed this effect. In explants with mesoderm/endoderm, RA-dependent SM neuron differentiation in rostral rhombomeres was restored by the application of an inhibitor of the RA-degrading enzyme CYP26. We found that the mesoderm/endoderm (either with or without RA) induced Cyp26 expression in the neuroepithelium in vitro, suggesting that the modulatory effect of CYP26 on RA-dependent patterning might be dependent on local signals.
authors.affiliation: MRC Centre for Developmental Neurobiology, 4th Floor New Hunt's House, King's College, Guy's Campus, London SE1 1UL, UK. sarah.guthrie@kcl.ac.uk
authors.forename: Sonia
authors.initials: S
authors.lastname: Guidato
authors.forename: Camilla
authors.initials: C
authors.lastname: Barrett
authors.forename: Sarah
authors.initials: S
authors.lastname: Guthrie
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D052160:Benzothiazoles; D002478:Cells, Cultured; D002642:Chick Embryo; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004707:Endoderm / Q000166:cytology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018398:Homeodomain Proteins / Q000235:genetics; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D060850:LIM-Homeodomain Proteins; D008648:Mesoderm / Q000166:cytology; D009046:Motor Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D009419:Nerve Tissue Proteins; D000072516:Retinoic Acid 4-Hydroxylase; D012249:Rhombencephalon / Q000166:cytology* / Q000196:embryology; D013844:Thiazoles / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics; D014212:Tretinoin / Q000494:pharmacology*; D014230:Triazoles / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D052160:Benzothiazoles; D065607:Cytochrome P-450 Enzyme Inhibitors; D018398:Homeodomain Proteins; C489520:Hoxd4 protein, mouse; D060850:LIM-Homeodomain Proteins; D009419:Nerve Tissue Proteins; D013844:Thiazoles; D014157:Transcription Factors; D014230:Triazoles; C063843:insulin gene enhancer binding protein Isl-1; D014212:Tretinoin; D003577:Cytochrome P-450 Enzyme System; D000072516:Retinoic Acid 4-Hydroxylase; C406527:R 115866