Chronic glucocorticoid exposure in early development leads to neuroendocrine, metabolic, and immune dysregulation in adult zebrafish
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ABSTRACT: Chronic early life stress can affect development of the neuroendocrine stress system, leading to its persistent dysregulation and consequently increased disease risk in adulthood. One contributing factor is thought to be epigenetic programming in response to chronic glucocorticoid exposure during early development. We have previously shown that zebrafish embryos treated chronically with cortisol develop into adults with constitutively elevated whole body cortisol and aberrant immune gene expression. The objective of the experiments reported here was to further characterize the phenotype of those adults. We find that adult zebrafish derived from cortisol-treated embryos have aberrant cortisol tissue distribution and dynamics, which correlate with differential transcriptional activity of key glucocorticoid-responsive regulatory genes klf9 and fkbp5 in blood and brain.
Project description:Chronic early life stress increases adult susceptibility to numerous health problems linked to chronic inflammation. One way that this may occur is via glucocorticoid-induced developmental programming. To gain insight into such programming, we treated zebrafish embryos with cortisol and examined the effects on adults. In adulthood, the treated fish maintained elevated basal cortisol levels in the absence of exogenous cortisol, and constitutively mis-expressed genes involved in defense response and its regulation. Adults derived from cortisol-treated embryos displayed defective tailfin regeneration, heightened basal expression of pro-inflammatory genes, and failure to appropriately regulate those genes following injury or immunological challenge. These results support the hypothesis that chronically elevated glucocorticoid signaling early in life directs development of a pro-inflammatory adult phenotype, at the expense of immunoregulation and somatic regenerative capacity. 30 samples total were analyzed. 9 caudal fins samples (0, 2 and 4dpa), 3 blood samples and 3 muscle samples from adults exposed to DMSO control as embryos. 9 caudal fins samples (0, 2 and 4dpa), 3 blood samples and 3 muscle samples from adults exposed to cortisol (1 micromolar) as embryos.
Project description:Chronic early life stress increases adult susceptibility to numerous health problems linked to chronic inflammation. One way that this may occur is via glucocorticoid-induced developmental programming. To gain insight into such programming, we treated zebrafish embryos with cortisol and examined the effects on adults. In adulthood, the treated fish maintained elevated basal cortisol levels in the absence of exogenous cortisol, and constitutively mis-expressed genes involved in defense response and its regulation. Adults derived from cortisol-treated embryos displayed defective tailfin regeneration, heightened basal expression of pro-inflammatory genes, and failure to appropriately regulate those genes following injury or immunological challenge. These results support the hypothesis that chronically elevated glucocorticoid signaling early in life directs development of a pro-inflammatory adult phenotype, at the expense of immunoregulation and somatic regenerative capacity.
Project description:Chronic early life stress increases adult susceptibility to numerous health problems linked to chronic inflammation. One way that this may occur is via glucocorticoid-induced developmental programming. To gain insight into such programming we treated zebrafish embryos with 1 micromolar cortisol and examined the effects on larvae. Treated larvae had elevated whole-body cortisol and glucocorticoid signaling, and up-regulated genes associated with defense response and immune system processes. 6 samples total were analyzed. 3 DMSO controls, and 3 cortisol treated (1 micromolar).
Project description:Chronic early life stress increases adult susceptibility to numerous health problems linked to chronic inflammation. One way that this may occur is via glucocorticoid-induced developmental programming. To gain insight into such programming we treated zebrafish embryos with 1 micromolar cortisol and examined the effects on larvae. Treated larvae had elevated whole-body cortisol and glucocorticoid signaling, and up-regulated genes associated with defense response and immune system processes.
Project description:We found that a frameshift deletion introduced into exon 1 of zebrafish klf9 eliminates the DNA binding domain and significantly reduces expression of the mature transcript. RNA-seq shows that klf9 is required for the pro-inflammatory transcriptomic effects of chronic cortisol treatment. klf9 is one of a core set of genes consistently found to be upregulated by chronic cortisol exposure.
Project description:While the paradigm that genetic predisposition and environmental exposures interact to shape development and function of the human brain and ultimately the risk of psychiatric disorders has drawn wide interest, the corresponding molecular mechanisms have not been elucidated yet. Here we show that a functional polymorphism altering chromatin interaction between the transcription start site and long range enhancers in the FK506 binding protein 5 (FKBP5) gene, an important regulator of the stress hormone system, increases the risk of developing stress-related psychiatric disorders in adulthood by allele-specific, childhood trauma-dependent DNA demethylation in functional glucocorticoid response elements (GREs) of FKBP5. This demethylation is linked to increased stress-dependent gene transcription followed by a long-term dysregulation of the stress hormone system and a global impact on the function of immune cells and brain areas associated with stress regulation. This first identification of molecular mechanisms of genotype-directed long-term environmental reactivity will also critically contribute to designing more effective treatment strategies for stress-related disorders. Effects of FKBP5 rs1360780 genotype x environment interaction on peripheral blood mRNA expression of GR responsive genes, as measured by gene expression arrays, were explored in 129 individuals (child abuse/risk allele carrier N = 40, child abuse/protective allele carrier N = 15; and no child abuse/risk allele carrier N = 60, no child abuse/protective allele carrier N = 14). In all 129 individuals, 1627 transcripts showed a significant correlation with plasma cortisol concentrations, suggesting their GR responsiveness. The correlation of 76 of these transcripts with cortisol plasma levels showed significant differences when stratifying by FKBP5 genotype in individuals with child abuse (Fisher z score ≥ 1.96) For these 76 transcripts, the mean absolute correlation coefficient with plasma cortisol was R = 0.23 in the risk allele carriers with child abuse, that is those exhibiting a demethylation of FKBP5 intron 7 as compared to R = 0.74 in the carriers of the protective genotype with child abuse where intron 7 methylation remains largely stable. This indicates a relative GR-resistance in the trauma exposed FKBP5 risk allele vs. protective genotype carriers. These 76 transcripts did not show a genotype-dependent difference in correlation coefficients in non-trauma exposed individuals suggesting that exposure to early trauma enhances FKBP5 genotype-dependent effect of GR sensitivity, most likely by epigenetic mechanisms. These findings suggest that the combination of FKBP5 risk allele carrier status and early trauma exposure alters the stress hormone-dependent regulation of several genes in peripheral blood cells, and might thereby enhance the reported association of early trauma with immune and inflammatory dysregulation, further promoting system-wide symptoms of stress-related disorders.
Project description:Exposure to serious or traumatic events early in life can lead to persistent alterations in physiological stress response systems, including enhanced cross-talk between the neuroendocrine and immune system. These programming effects may be mechanistically involved in mediating the effects of adverse childhood experience on disease risk in adulthood. Here, we investigated neuroendocrine as well as genome-wide mRNA expression responses in monocytes to acute stress exposure, in a sample of healthy adults (n=30) with a history of early childhood adversity, and a control group (n=30) without trauma experience. The early adversity group showed altered hypothalamus-pituitary-adrenal (HPA) axis responses to stress, evidenced by lower ACTH and cortisol responses. Analyses of gene expression patterns showed a larger stress-induced increase of cardinal pro-inflammatory transcripts IL6 and FOSB, and an increased activity of pro-inflammatory upstream signaling in the early adversity group. We also identified transcripts that were differentially correlated with stress-induced cortisol increases between the groups. Noteworthy, FKBP5 expression was less responsive to cortisol induction in the early adversity group, with potential effects on the ultra-short feedback loop that balances FKBP5 and glucocorticoid receptor activity. Further exploratory analyses showed differential stress-induced regulation of gene transcription between the groups. Prominent among the differentially regulated transcripts were those coding for genes involved in signal transducer activity, G-protein coupled receptors, and several genes involved in serotonin receptor signaling. We suggest that childhood adversity leads to persistent alterations in transcriptional control of stress responsive pathways, which - when chronically or repeatedly activated - might predispose individuals to stress-related psychopathology.
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.