title: Visualization of estrogen receptor transcriptional activation in zebrafish.
abstract: Estrogens regulate a diverse range of physiological processes and affect multiple tissues. Estrogen receptors (ERs) regulate transcription by binding to DNA at conserved estrogen response elements, and such elements have been used to report ER activity in cultured cells and in transgenic mice. We generated stable, transgenic zebrafish containing five consecutive elements upstream of a c-fos minimal promoter and green fluorescent protein (GFP) to visualize and quantify transcriptional activation in live larvae. Transgenic larvae show robust, dose-dependent estrogen-dependent fluorescent labeling in the liver, consistent with er gene expression, whereas ER antagonists inhibit GFP expression. The nonestrogenic steroids dexamethasone and progesterone fail to activate GFP, confirming ER selectivity. Natural and synthetic estrogens activated the transgene with varying potency, and two chemicals, genistein and bisphenol A, preferentially induce GFP expression in the heart. In adult fish, fluorescence was observed in estrogenic tissues such as the liver, ovary, pituitary gland, and brain. Individual estrogen-responsive neurons and their projections were visualized in the adult brain, and GFP-positive neurons increased in number after 17β-estradiol exposure. The transgenic estrogen-responsive zebrafish allow ER signaling to be monitored visually and serve as in vivo sentinels for detection of estrogenic compounds.
authors.affiliation: Carnegie Institution for Science, Department of Embryology, 3520 San Martin Drive, Baltimore, Maryland 21218, USA. gorelick@ciwemb.edu
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Gorelick
authors.forename: Marnie E
authors.initials: ME
authors.lastname: Halpern
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D016384:Consensus Sequence; D004305:Dose-Response Relationship, Drug; D004965:Estrogen Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D004968:Estrogens, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D017930:Genes, Reporter / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D057054:Molecular Imaging / Q000379:methods*; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009928:Organ Specificity; D048789:Phytoestrogens / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004965:Estrogen Antagonists; D004968:Estrogens, Non-Steroidal; D009419:Nerve Tissue Proteins; D048789:Phytoestrogens; D016760:Proto-Oncogene Proteins c-fos; D011960:Receptors, Estrogen; D029961:Zebrafish Proteins; D049452:Green Fluorescent Proteins