title: Functional analysis reveals no transcriptional role for the glucocorticoid receptor β-isoform in zebrafish.
abstract: In humans, two splice variants of the glucocorticoid receptor (GR) exist: the canonical α-isoform, and the β-isoform, which has been shown to have a dominant-negative effect on hGRα. Previously, we have established the occurrence of a GR β-isoform in zebrafish, and in the present study we have investigated the functional role of the zebrafish GRβ (zGRβ). Reporter assays in COS-1 cells demonstrated a dominant-negative effect of zGRβ but no such effect was observed in zebrafish PAC2 cells using induction of the fk506 binding protein 5 (fkbp5) gene as readout. Subsequently, we generated a transgenic fish line with inducible expression of zGRβ. Transcriptome analysis suggested transcriptional regulation of genes by zGRβ in this line, but further validation failed to confirm this role. Based on these results, its low expression level and its poor evolutionary conservation, we suggest that the zebrafish GR β-isoform does not have a functional role in transcriptional regulation.
authors.affiliation: Institute of Biology (IBL), Leiden University, Leiden, The Netherlands.
authors.forename: Antonia
authors.initials: A
authors.lastname: Chatzopoulou
authors.affiliation: Institute of Biology (IBL), Leiden University, Leiden, The Netherlands.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Schoonheim
authors.affiliation: Institute of Biology (IBL), Leiden University, Leiden, The Netherlands.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Torraca
authors.affiliation: Institute of Biology (IBL), Leiden University, Leiden, The Netherlands.
authors.forename: Annemarie H
authors.initials: AH
authors.lastname: Meijer
authors.affiliation: Institute of Biology (IBL), Leiden University, Leiden, The Netherlands.
authors.forename: Herman P
authors.initials: HP
authors.lastname: Spaink
authors.affiliation: Institute of Biology (IBL), Leiden University, Leiden, The Netherlands. Electronic address: m.j.m.schaaf@biology.leidenuniv.nl.
authors.forename: Marcel J M
authors.initials: MJ
authors.lastname: Schaaf
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D004625:Embryo, Nonmammalian / Q000378:metabolism; D063990:Gene Ontology; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000235:genetics; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*
chemical_list: D020033:Protein Isoforms; D011965:Receptors, Glucocorticoid; C121943:glucocorticoid receptor beta; D049452:Green Fluorescent Proteins; D008156:Luciferases
keywords: Beta-isoform; Corticosteroid; Glucocorticoid receptor; Microarray; Transcriptome analysis; Zebrafish