title: Transcriptional and metabolic effects of glucocorticoid receptor α and β signaling in zebrafish.
abstract: In humans and zebrafish, 2 glucocorticoid (GC) receptor (GR) splice variants exist: the canonical GR α-isoform (GRα), and the GRβ. In the present study, we have used the zebrafish model system in order to reveal genes affected by each of these 2 receptor isoforms. By injecting zebrafish embryos with different splice-blocking morpholinos, we could knock down both GR isoforms or could target the alternative splicing of the GR pre-mRNA in favor of the GRβ. In addition, specific GRβ overexpression was achieved by injecting mRNA. Embryos were treated with the synthetic GC dexamethasone, and transcriptome analysis was performed. Two distinct gene clusters were found that were regulated by GRα: one that was regulated by GRα under basal conditions (presence of endogenous cortisol only), and one that was regulated upon increased activation of GRα (using a pharmacological dose of dexamathasone). GRβ may act as a dominant-negative inhibitor of GRα when GRβ is overexpressed and the GRα expression level is knocked down simultaneously. However, without GRα knockdown, no evidence for this activity was found. In addition, the data indicate regulation of gene transcription through other mechanisms of action by GRβ. We also investigated the concentrations of several metabolites using nuclear magnetic resonance spectroscopy. We found that dexamethasone treatment and knockdown of GRα together with overexpression of GRβ had opposite effects on glucose, amino acid, and fatty acid levels. Thus, we have shed new light on the molecular mechanisms of GC-induced effects on metabolism, which are known to increase the risk of obesity, hyperglycemia, and diabetes.
authors.affiliation: Department of Animal Sciences and Health (A.C., A.H.M., H.P.S., M.J.M.S.), Institute of Biology, Leiden University, 2333CC Leiden, The Netherlands; Department of Biophysical Organic Chemistry/Solid State NMR (U.R., A.A.), Leiden Institute of Chemistry, Leiden University, 2333CC Leiden, The Netherlands; and Institute of Medical Physics and Biophysics (A.A.), University of Leipzig, D-04107 Leipzig, Germany.
authors.forename: Antonia
authors.initials: A
authors.lastname: Chatzopoulou
authors.forename: Upasana
authors.initials: U
authors.lastname: Roy
authors.forename: Annemarie H
authors.initials: AH
authors.lastname: Meijer
authors.forename: A
authors.initials: A
authors.lastname: Alia
authors.forename: Herman P
authors.initials: HP
authors.lastname: Spaink
authors.forename: Marcel J M
authors.initials: MJ
authors.lastname: Schaaf
mesh_terms: D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D004625:Embryo, Nonmammalian; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D005938:Glucocorticoids / Q000494:pharmacology; D055442:Metabolome / Q000187:drug effects / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D011965:Receptors, Glucocorticoid / Q000819:agonists / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome / Q000187:drug effects / Q000235:genetics*; D015027:Zebrafish
chemical_list: D005938:Glucocorticoids; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; C411470:glucocorticoid receptor alpha; C121943:glucocorticoid receptor beta; D003907:Dexamethasone