title: Pituitary corticotroph ontogeny and regulation in transgenic zebrafish.
abstract: We characterized zebrafish proopiomelanocortin (POMC) gene promoter, and sequence analysis revealed that the promoter contains regulatory elements conserved among vertebrate species. To monitor the ontogeny of the pituitary POMC lineage in living vertebrates, we generated transgenic zebrafish expressing green fluorescent protein (GFP) driven by the POMC promoter. Zebrafish POMC-GFP is first expressed asymmetrically as two bilateral groups of cells most anterior to the neural ridge midline at 18-20 h post fertilization (hpf). POMC-GFP-positive cells then fuse into a single-cell mass within the pituitary anlage after 24 hpf and subsequently organize as distinct anterior and posterior domains between 48 and 64 hpf. Immunohistochemical studies with ACTH and alphaMSH antisera showed that POMC-GFP was mainly targeted to both anterior and posterior pituitary corticotrophs, whereas posterior pituitary region melanotrophs did not express GFP. To determine in vivo zebrafish corticotroph responses, dexamethasone (10(-5) m) was added to live embryos, which selectively suppressed POMC-GFP expression in the anterior group of corticotrophs, suggesting a distinct domain that is responsive to glucocorticoid feedback. Transgenic zebrafish with specific POMC-GFP expression in pituitary corticotrophs offers a powerful genetic system for in vivo study of vertebrate corticotroph lineage development.
authors.affiliation: Department of Medicine, Cedars-Sinai Research Institute, University of California Los Angeles School of Medicine, 90048, USA.
authors.forename: Ning-Ai
authors.initials: NA
authors.lastname: Liu
authors.forename: Haigen
authors.initials: H
authors.lastname: Huang
authors.forename: Zhongan
authors.initials: Z
authors.lastname: Yang
authors.forename: Wiebke
authors.initials: W
authors.lastname: Herzog
authors.forename: Matthias
authors.initials: M
authors.lastname: Hammerschmidt
authors.forename: Shuo
authors.initials: S
authors.lastname: Lin
authors.forename: Shlomo
authors.initials: S
authors.lastname: Melmed
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D019070:Cell Lineage; D017124:Conserved Sequence; D003907:Dexamethasone / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D004625:Embryo, Nonmammalian / Q000187:drug effects; D005260:Female; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000196:embryology / Q000502:physiology*; D011333:Pro-Opiomelanocortin / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014714:Vertebrates / Q000235:genetics; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D008164:Luminescent Proteins; D029961:Zebrafish Proteins; C474117:pomca protein, zebrafish; D049452:Green Fluorescent Proteins; D011333:Pro-Opiomelanocortin; D003907:Dexamethasone