Genetic Differences in the Immediate Transcriptome Response to Stress Predict Risk-Related Brain Function and Psychiatric Disorders
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ABSTRACT: Depression risk is exacerbated by genetic factors and stress exposure; however, the biological mech- anisms through which these factors interact to confer depression risk are poorly understood. One putative biological mechanism implicates variability in the ability of cortisol, released in response to stress, to trigger a cascade of adaptive genomic and non-genomic processes through glucocorticoid receptor (GR) activation. Here, we demonstrate that common genetic variants in long-range enhancer elements modulate the immediate transcriptional response to GR activation in human blood cells. These functional genetic variants increase risk for depression and co-heritable psychiatric disorders. Moreover, these risk variants are associated with inappropriate amygdala reactivity, a transdiagnostic psychiatric endophenotype and an important stress hormone response trigger. Network modeling and animal experiments suggest that these genetic dif- ferences in GR-induced transcriptional activation may mediate the risk for depression and other psy- chiatric disorders by altering a network of function- ally related stress-sensitive genes in blood and brain.
Project description:While exposure to adverse life events and subsequent dysregulation of the stress hormone response broadly confer risk for depression, the specific molecular mechanisms mediating this risk are poorly understood. Through pharmacologic activation of the stress hormone response in blood cells we demonstrate that common genetic variants in long-range enhancer elements moderate the immediate transcriptome response to stress, and that these genetic differences are associated with increased risk for depression in the context of early adversity. Using imaging genetics we then link these common risk variants with dysregulated amygdala reactivity, an important trigger of the stress hormone response. The transcripts regulated by these risk variants in peripheral blood were also responsive to stress and stress hormone receptor activation in murine brain. Network modeling approaches suggest that these differences in transcriptional activation may mediate stress-related risk for depression by altering a functional gene network related to proteasome degradation and synaptic plasticity. A Dexamethasone Suppression Test was performed in 160 male subjects. Baseline and stimulated (3 hours after 1.5 mg dexamethasone p.o.) whole blood samples were analyzed using Illumina Human HT-12 v3 arrays.
Project description:Early-life adversity is an important risk factor for major depressive disorder (MDD) and schizophrenia (SCZ) that interacts with genetic factors to confer disease risk through mechanisms that are still insufficiently understood. One downstream effect of early-life adversity is the activation of glucocorticoid receptor (GR)-dependent gene networks that drive acute and long-term adaptive behavioral and cellular responses to stress. We have previously shown that genetic variants that moderate GR-induced gene transcription (GR-response eSNPs) are significantly enriched among risk variants from genome-wide association studies (GWASs) for MDD and SCZ. Here, we show that the 63 transcripts regulated by these disease-associated functional genetic variants form a tight glucocorticoid-responsive co-expression network (termed GCN). We hypothesized that changes in the correlation structure of this GCN may contribute to early-life adversity-associated disease risk. Therefore, we analyzed the effects of different qualities of social support and stress throughout life on GCN formation across distinct brain regions using a translational mouse model. We observed that different qualities of social experience substantially affect GCN structure in a highly brain region-specific manner. GCN changes were predominantly found in two functionally interconnected regions, the ventral hippocampus and the hypothalamus, two brain regions previously shown to be of relevance for the stress response, as well as psychiatric disorders. Overall, our results support the hypothesis that a subset of genetic variants may contribute to risk for MDD and SCZ by altering circuit-level effects of early and adult social experiences on GCN formation and structure.
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:In psychiatric disorders, common and rare genetic variants cause widespread dysfunction of cells and their interactions, especially in the prefrontal cortex, giving rise to psychiatric symptoms. To better understand these processes, we traced the effects of common and rare genetics, and cumulative disease risk scores, to their molecular footprints in human cortical single-cell types. We demonstrated that examining gene expression at single-exon resolution is crucial for understanding the cortical dysregulation associated with diagnosis and genetic risk derived from common variants. We then used disease risk scores to identify a core set of genes that serve as a footprint of common and rare variants in the cortex. Pathways enriched in these genes included dopamine regulation, circadian entrainment, and hormone regulation. Single-nuclei-RNA-sequencing pinpointed these enriched genes to excitatory cortical neurons. This study highlights the importance of studying sub-gene-level genetic architecture to classify psychiatric disorders based on biology rather than symptomatology, to identify novel targets for treatment development.
Project description:Depression, or major depressive disorder, poses a significant burden for both individuals and society, affecting approximately 10.8% of the general population. This psychiatric disorder leads to approximately 800,000 deaths per year. A combination of genetic and environmental factors such as early life stress (ELS) increase the risk for development of depression in humans, and a clear role for the hippocampus in the pathophysiology of depression has been shown. Nevertheless, the underlying mechanisms of depression remain poorly understood, resulting in a lack of effective treatments. To better understand the core mechanisms underlying the development of depression, we used a cross-species design to investigate shared hippocampal pathophysiological mechanisms in mouse ELS and human depression. Mice were subjected to ELS by a maternal separation paradigm, followed by RNA sequencing analysis of the adult hippocampal tissue. This identified persistent transcriptional changes linked to mitochondrial stress response pathways, with oxidative phosphorylation and protein folding emerging as the main mechanisms affected by maternal separation. Remarkably, there was a significant overlap between the pathways involved in mitochondrial stress response we observed and publicly available RNAseq data from hippocampal tissue of depressive patients. This cross-species conservation of changes in gene expression of mitochondria-related genes suggests that mitochondrial stress may play a pivotal role in the development of depression. Our findings highlight the potential significance of the hippocampal mitochondrial stress response as a core mechanism underlying the development of depression. Further experimental investigations are required to expand our understanding of these mechanisms
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).
Project description:Maternal stress, anxiety, and depression increase the risk of psychiatric disorders in the progeny. These maternal effects can extend beyond the first generation and affect the grandchildren. In contrast to paternal, maternal effects can impact the offspring not only during gametogenesis, but also through fetal and early-postnatal life, increasing phenotypic complexity and the overall impact. To better understand its non-genetic structure, we dissected a complex maternally-transmitted phenotype to elementary behaviors and their corresponding transmission mechanisms. Chronic stress and depression are associated with reduced serotonin1A receptor (5-HT1AR) levels, and we reported that 5-HT1AR+/- dams transmit anxiety/stress-reactivity traits to their wild-type offspring. Here we show that the maternal effect is propagated to multiple generations, and that the behavioral traits are not transmitted in unison, but rather via parallel and segregated mechanisms, each with generation-dependent penetrance and gender specificity. The ârisk-avoidanceâ and âhypoactivityâ traits of anxiety were transmitted, via a neuro-immune pathway, consecutively from mother to the wild-type F1, F2, and occasionally F3 generation by iterative non-gametic-programming, while the âincreased stress-reactivityâ trait was transmitted to the F2 generation by gametic-programming. Iterative non-gametic-programming of anxiety was linked, via gene expression changes and clustered DNA hypo/hypermethylation at intragenic enhancers, to sphingolipid metabolism and GPCRs in the F1/F2 hippocampus, suggesting dysregulated lipid raft functioning/transmembrane signaling. Conversely, gametic-programming of behavior was predominantly associated with hypomethylation at different promoter-enhancing sequences within a set of genes with diverse neuronal functions. Since differential methylation appeared only postnatally in F2 neurons and was absent in F3 neurons, it is secondary to earlier F2 gametic changes that survive reprogramming in the early embryo, but are erased in F3 germ-cells. Our data introduce parallel and segregated non-genetic transmission of traits as a mechanism that may explain the propagation and pleiotropy of complex behavioral and psychiatric disease phenotypes across generations. Compared three generations of male offspring from wild-type and 5HT1A-R-/+ Swiss Webster mothers with two replicates per sample. Included as well is F2 embryo transfer from wild-type and het parents in wild-type surogates
Project description:Recent genetic studies have found common genomic risk variants among psychiatric disorders, strongly suggesting the overlaps in their molecular and cellular mechanism. Our research group identified the variant in ASTN2 as one of the candidate risk factors across these psychiatric disorders by whole-genome copy number variation analysis. However, the alterations in the human neuronal cells resulting from ASTN2 variants identified in patients remain unknown. To address this, we used patient-derived and genome-edited iPS cells with ASTN2 deletion; cells were further differentiated into neuronal cells. A comprehensive gene expression analysis using genome-edited iPSC cells with the loss of function variants on both alleles revealed that the expression level of ZNF558, a gene specifically expressed in human forebrain neural progenitor cells, was greatly reduced in ASTN2-deleted neuronal cells.
Project description:Adverse experiences in early life are risk factors for the development of behavioral and physiological symptoms that can lead to psychiatric and cognitive disorders later in life. Some of these symptoms can be transmitted to the offspring, in some cases by non-genomic mechanisms involving germ cells. Using a mouse model of unpredictable maternal separation and maternal stress, we show that postnatal trauma alters coping behaviors in adverse conditions in exposed males when adult and in their adult male progeny. The behavioral changes are accompanied by increased glucocorticoid receptor (GR) expression and decreased DNA methylation of the GR promoter in the hippocampus. DNA methylation is also decreased in sperm cells of exposed males when adult. Transgenerational transmission of behavioral symptoms is prevented by paternal environmental enrichment, an effect associated with the reversal of alterations in GR gene expression and DNA methylation in the hippocampus of the male offspring. These findings highlight the influence of both, negative and positive environmental factors on behavior across generations, and the plasticity of the epigenome across life.
Project description:Maternal stress, anxiety, and depression increase the risk of psychiatric disorders in the progeny. These maternal effects can extend beyond the first generation and affect the grandchildren. In contrast to paternal, maternal effects can impact the offspring not only during gametogenesis, but also through fetal and early-postnatal life, increasing phenotypic complexity and the overall impact. To better understand its non-genetic structure, we dissected a complex maternally-transmitted phenotype to elementary behaviors and their corresponding transmission mechanisms. Chronic stress and depression are associated with reduced serotonin1A receptor (5-HT1AR) levels, and we reported that 5-HT1AR+/- dams transmit anxiety/stress-reactivity traits to their wild-type offspring. Here we show that the maternal effect is propagated to multiple generations, and that the behavioral traits are not transmitted in unison, but rather via parallel and segregated mechanisms, each with generation-dependent penetrance and gender specificity. The “risk-avoidance” and “hypoactivity” traits of anxiety were transmitted, via a neuro-immune pathway, consecutively from mother to the wild-type F1, F2, and occasionally F3 generation by iterative non-gametic-programming, while the “increased stress-reactivity” trait was transmitted to the F2 generation by gametic-programming. Iterative non-gametic-programming of anxiety was linked, via gene expression changes and clustered DNA hypo/hypermethylation at intragenic enhancers, to sphingolipid metabolism and GPCRs in the F1/F2 hippocampus, suggesting dysregulated lipid raft functioning/transmembrane signaling. Conversely, gametic-programming of behavior was predominantly associated with hypomethylation at different promoter-enhancing sequences within a set of genes with diverse neuronal functions. Since differential methylation appeared only postnatally in F2 neurons and was absent in F3 neurons, it is secondary to earlier F2 gametic changes that survive reprogramming in the early embryo, but are erased in F3 germ-cells. Our data introduce parallel and segregated non-genetic transmission of traits as a mechanism that may explain the propagation and pleiotropy of complex behavioral and psychiatric disease phenotypes across generations.