title: A transgenic zebrafish model for monitoring glucocorticoid receptor activity.
abstract: Gene regulation resulting from glucocorticoid receptor and glucocorticoid response element interactions is a hallmark feature of stress response signaling. Imbalanced glucocorticoid production and glucocorticoid receptor activity have been linked to socioeconomically crippling neuropsychiatric disorders, and accordingly there is a need to develop in vivo models to help understand disease progression and management. Therefore, we developed the transgenic SR4G zebrafish reporter line with six glucocorticoid response elements used to promote expression of a short half-life green fluorescent protein following glucocorticoid receptor activation. Herein, we document the ability of this reporter line to respond to both chronic and acute exogenous glucocorticoid treatment. The green fluorescent protein expression in response to transgene activation was high in a variety of tissues including the brain, and provided single-cell resolution in the effected regions. The specificity of these responses is demonstrated using the partial agonist mifepristone and mutation of the glucocorticoid receptor. Importantly, the reporter line also modeled the temporal dynamics of endogenous stress response signaling, including the increased production of the glucocorticoid cortisol following hyperosmotic stress and the fluctuations of basal cortisol concentrations with the circadian rhythm. Taken together, these results characterize our newly developed reporter line for elucidating environmental or genetic modifiers of stress response signaling, which may provide insights to the neuronal mechanisms underlying neuropsychiatric disorders such as major depressive disorder.
authors.affiliation: Department of Biochemistry and Molecular Biology.|Mayo Graduate School, Mayo Clinic, Rochester, MN, USA.
authors.forename: R G
authors.initials: RG
authors.lastname: Krug
authors.affiliation: Department of Biochemistry and Molecular Biology.
authors.forename: T L
authors.initials: TL
authors.lastname: Poshusta
authors.affiliation: Department of Biochemistry and Molecular Biology.
authors.forename: K J
authors.initials: KJ
authors.lastname: Skuster
authors.affiliation: Department of Biochemistry and Molecular Biology.
authors.forename: M R
authors.initials: MR
authors.lastname: Berg
authors.affiliation: Department of Biochemistry and Molecular Biology.
authors.forename: S L
authors.initials: SL
authors.lastname: Gardner
authors.affiliation: Department of Biochemistry and Molecular Biology.
authors.forename: K J
authors.initials: KJ
authors.lastname: Clark
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics; D001921:Brain / Q000378:metabolism / Q000502:physiology; D002940:Circadian Rhythm; D006854:Hydrocortisone / Q000378:metabolism; D015735:Mifepristone / Q000494:pharmacology; D009997:Osmotic Pressure; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D020218:Response Elements; D015027:Zebrafish / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D029961:Zebrafish Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism
chemical_list: D011965:Receptors, Glucocorticoid; D029961:Zebrafish Proteins; D015735:Mifepristone; D006854:Hydrocortisone
keywords: Circadian rhythm; GFP reporter line; HPA axis; cortisol; fluticasone propionate; glucocorticoid receptor; glucocorticoid response element; mifepristone; stress; transgenic zebrafish