The transcriptomics of glucocorticoid receptor signaling in developing zebrafish.
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ABSTRACT:
SUBMITTER: Nesan D
PROVIDER: S-EPMC3858477 | biostudies-literature | 2013
REPOSITORIES: biostudies-literature
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Project description:The glucocorticoid receptor (GR) regulates gene expression upon activation by glucocorticoid (GC) hormones. In zebrafish, two GR splice variants exist: the canonical GR M-NM-1-isoform (GRM-NM-1), and the GR M-NM-2-isoform (GRM-NM-2). The exact function of GRb remains elusive. We have investigated the transcriptional role of GRa and GRb in the zebrafish embryo model by injecting mebryos with two splice-blocking morpholinos (one leading to knockdown of both GR M-NM-1- and M-NM-2-isoforms, and another targeting the alternative splicing of the GR pre-mRNA in favor of the GR M-NM-2-isoform) and with GRM-NM-2 mRNA (resulting in specific GRM-NM-2 overexpression). Transcriptome profiling was performed on total RNA isolated from 30 hpf embryos. Our results show that GRb does not act as a dominant-negative inhibitor of GRa, and that GRa regulates two distinct gene clusters, which are mainly involved in the metabolism of the embryo. This microarray study was designed to determine the effect of knockdown and overexpression of GRa and GRb. For this purpose, wild type (AB/TL) zebrafish embryos were injected at the 1-2 cell stage with a standard control morpholino (SC-MO), a splice-blocking morpholino leading to knockdown of both GR M-NM-1- and M-NM-2-isoforms (MO1), a splice-blocking morpholino targeting the alternative splicing of the GR pre-mRNA in favor of the GR M-NM-2-isoform (MO2), or GRb mRNA. At 24 hpf, each group was treated with dexamathasone (or vehicle) for 6 hr. This resulted in 8 treament groups: SC-MO/veh, SC-MO/dex, MO1/veh, MO1/dex, MO2/veh, MO2/dex, GRb mRNA/veh, GRb mRNA/dex. After the incubation period, embryos were collected and RNA was isolated from 20 embryos per treatment group (30 hpf). Three individual experiments were performed, and the resulting triplicate samples were analyzed by microarray, using a common reference approach.
2014-11-18 | E-GEOD-63360 | biostudies-arrayexpress
Project description:The glucocorticoid receptor (GR) regulates gene expression upon activation by glucocorticoid (GC) hormones. In zebrafish, two GR splice variants exist: the canonical GR α-isoform (GRα), and the GR β-isoform (GRβ). The exact function of GRb remains elusive. We have investigated the transcriptional role of GRa and GRb in the zebrafish embryo model by injecting mebryos with two splice-blocking morpholinos (one leading to knockdown of both GR α- and β-isoforms, and another targeting the alternative splicing of the GR pre-mRNA in favor of the GR β-isoform) and with GRβ mRNA (resulting in specific GRβ overexpression). Transcriptome profiling was performed on total RNA isolated from 30 hpf embryos. Our results show that GRb does not act as a dominant-negative inhibitor of GRa, and that GRa regulates two distinct gene clusters, which are mainly involved in the metabolism of the embryo.
2014-11-18 | GSE63360 | GEO
Project description:To further characterize the roles of cortisol signaling via the glucocorticoid receptor (GR) in developing zebrafish, we have used morpholino oligonucleotides to knockdown GR protein translation and measured gene expression in RNA extracted from 24 and 36 hours post fertilization (hpf) embryos. The GR morpholino was characterized previously in Nesan et al., 2012, Endocrinology 181, 35-44) Single-cell zebrafish embryos were microinjected with either active morpholino or mispair control. Embryos were frozen at 24 and 36 hpf and total RNA extracted for microarray analysis. Three independent replicates (different breeding events on separate days) were performed for each treatment per timepoint.
2013-08-28 | E-GEOD-50376 | biostudies-arrayexpress
Project description: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.
| S-EPMC4177977 | biostudies-literature
Project description:Glucocorticoids modulate diverse aspects of physiology and behavior, including energy homeostasis, stress response, and memory, through activation of the glucocorticoid receptor (GR). Light perception has profound effects on the production of glucocorticoids via functional connections of the retina to the hypothalamus-pituitary-adrenal axis. We report here that glucocorticoids can also signal in the reverse direction, i. e., regulate visual function in zebrafish, Danio rerio. The zebrafish GR mutant, gr (s357) , harbors a missense mutation that completely blocks the transcriptional activity of GR. In this mutant, visual behavior was abolished following a period of darkness and recovered sluggishly after return to the light. Electrophysiological measurements showed that the photoresponse of the dark-adapted retina was reduced in the mutant and re-adapted to light with a substantial delay. Several gene products, including some that are important for dopaminergic signaling, were misregulated in gr (s357) mutants. We suggest that GR controls a gene network required for visual adaptation in the zebrafish retina and potentially integrates neuroendocrine and sensory responses to environmental changes.
| S-EPMC3781318 | biostudies-literature
Project description:The pleiotropic effects of glucocorticoids in metabolic, developmental, immune and stress response processes have been extensively investigated; conversely, their roles in reproduction are still less documented. It is well known that stress or long-lasting therapies can cause a strong increase in these hormones, negatively affecting reproduction. Moreover, the need of glucocorticoid (GC) homeostatic levels is highlighted by the reduced fertility reported in the zebrafish glucocorticoid receptor mutant (nr3c1ia30/ia30) line (hereafter named gr-/-). Starting from such evidence, in this study, we have investigated the role of glucocorticoid receptor (Gr) in the reproduction of female zebrafish. Key signals orchestrating the reproductive process at the brain, liver, and ovarian levels were analyzed using a multidisciplinary approach. An impairment of the kiss-GnRH system was observed at the central level in (gr-/-) mutants as compared to wild-type (wt) females while, in the liver, vitellogenin (vtg) mRNA transcription was not affected. Changes were instead observed in the ovary, particularly in maturing and fully grown follicles (classes III and IV), as documented by the mRNA levels of signals involved in oocyte maturation and ovulation. Follicles isolated from gr-/- females displayed a decreased level of signals involved in the acquisition of competence and maturation, causing a reduction in ovulation with respect to wt females. Fourier transform infrared imaging (FTIRI) analysis of gr-/- follicle cytoplasm showed major changes in macromolecule abundance and distribution with a clear alteration of oocyte composition. Finally, differences in the molecular structure of the zona radiata layer of gr-/- follicles are likely to contribute to the reduced fertilization rate observed in mutants.
| S-EPMC7729492 | biostudies-literature
Project description:To further characterize the roles of cortisol signaling via the glucocorticoid receptor (GR) in developing zebrafish, we have used morpholino oligonucleotides to knockdown GR protein translation and measured gene expression in RNA extracted from 24 and 36 hours post fertilization (hpf) embryos. The GR morpholino was characterized previously in Nesan et al., 2012, Endocrinology 181, 35-44)
2013-08-28 | GSE50376 | GEO
Project description:Upon binding of cortisol, the glucocorticoid receptor (GR) regulates the transcription of specific target genes, including those that encode the stress hormones corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone. Dysregulation of the stress axis is a hallmark of major depression in human patients. However, it is still unclear how glucocorticoid signaling is linked to affective disorders. We identified an adult-viable zebrafish mutant in which the negative feedback on the stress response is disrupted, due to abolition of all transcriptional activity of GR. As a consequence, cortisol is elevated, but unable to signal through GR. When placed into an unfamiliar aquarium ('novel tank'), mutant fish become immobile ('freeze'), show reduced exploratory behavior and do not habituate to this stressor upon repeated exposure. Addition of the antidepressant fluoxetine to the holding water and social interactions restore normal behavior, followed by a delayed correction of cortisol levels. Fluoxetine does not affect the overall transcription of CRH, the mineralocorticoid receptor (MR), the serotonin transporter (Serta) or GR itself. Fluoxetine, however, suppresses the stress-induced upregulation of MR and Serta in both wild-type fish and mutants. Our studies show a conserved, protective function of glucocorticoid signaling in the regulation of emotional behavior and reveal novel molecular aspects of how chronic stress impacts vertebrate brain physiology and behavior. Importantly, the zebrafish model opens up the possibility of high-throughput drug screens in search of new classes of antidepressants.
| S-EPMC4065652 | biostudies-literature
Project description:Reproductive decline in mid-adult females is an established phenotype of the ageing process. Stress and the rise in glucocorticoids (GCs) accelerate reproductive ageing, but little is known about the mechanisms involved. During stress, GCs activate the glucocorticoid receptor (GR), a ubiquitously expressed, ligand-bound transcription factor, to elicit physiological changes for restoring homeostasis. Here, we tested the hypothesis that GC-GR signalling is essential for accelerating reproductive ageing. To test this, we used a ubiquitous GR knockout (GRKO) zebrafish, which is inherently hypercortisolemic, to delineate the role of high cortisol and GR signalling on reproductive ageing. The loss of GR led to premature ovarian ageing, including high frequency of typical and atypical follicular atresia in vitellogenic oocytes, yolk liquefaction and large inflammatory infiltrates. The reduction in oocyte quality was also associated with a decline in ovarian tert expression in the adult GRKO fish compared to the early adult GRKO and adult wild-type zebrafish. Accelerated ovarian ageing also impacted the progeny, including lower breeding success, fecundity, egg fertilization rate and delayed somitogenesis and embryo survival in the adult GRKO fish. We adduce that GR signalling is essential for prolonging the reproductive lifespan and improving the egg quality and embryo viability in zebrafish.
| S-EPMC7739937 | biostudies-literature
Project description:Chronic cortisol exposure suppresses food intake in fish, but the central mechanism(s) involved in appetite regulation are unclear. Stress and the associated increase in cortisol levels increase hepatic gluconeogenesis, leading to hyperglycemia. As hyperglycemia causes a reduction in food intake, we tested the hypothesis that cortisol-induced hyperglycemia suppresses feeding in zebrafish (Danio rerio). We first established that stress-independent hyperglycemia suppressed food intake, and this corresponded with a reduction in the phosphorylation of the nutrient sensor, AMP-activated protein kinase (AMPK) in the brain. Chronic cortisol exposure also led to hyperglycemia and reduced food intake, but the mechanisms were distinct. In cortisol-exposed fish, there were no changes in brain glucose uptake or AMPK phosphorylation. Also, the phosphorylation of Akt and mTOR was reduced along with an increase in redd1, suggesting an enhanced capacity for proteolysis. Loss of the glucocorticoid receptor did not rescue cortisol-mediated feeding suppression but did increase glucose uptake and abolished the changes seen in mTOR phosphorylation and redd1 transcript abundance. Taken together, our results indicate that GR activation enhances brain proteolysis, and the associated amino acids levels, and not hyperglycemia, maybe a key mediator of the feeding suppression in response to chronic cortisol stimulation in zebrafish.
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