Project description:Steroid hormones act as important developmental switches and their nuclear receptors regulate many genes. However, few hormone-dependent enhancers have been characterized and important aspects of their sequence architecture, cell type-specific activating and repressing functions, or the regulatory roles of their chromatin structure have remained unclear. We used STARR-seq, a recently developed enhancer-screening assay, and ecdysone signaling in two different Drosophila cell types to derive the first genome-wide hormone-dependent enhancer activity maps. We demonstrate that enhancer activation depends on cis-regulatory motif combinations that differ between cell types and can predict cell type-specific ecdysone targeting. Activated enhancers are often not accessible prior to induction. Enhancer repression following hormone treatment is independent of receptor motifs and receptor binding to the enhancer as we show using ChIP-seq, but appears to rely on motifs for other factors, including Eip74. Our strategy is applicable to study signal-dependent enhancers for different pathways and across organisms.
Project description:Steroid hormones act as important developmental switches and their nuclear receptors regulate many genes. However, few hormone-dependent enhancers have been characterized and important aspects of their sequence architecture, cell type-specific activating and repressing functions, or the regulatory roles of their chromatin structure have remained unclear. We used STARR-seq, a recently developed enhancer-screening assay, and ecdysone signaling in two different Drosophila cell types to derive the first genome-wide hormone-dependent enhancer activity maps. We demonstrate that enhancer activation depends on cis-regulatory motif combinations that differ between cell types and can predict cell type-specific ecdysone targeting. Activated enhancers are often not accessible prior to induction. Enhancer repression following hormone treatment is independent of receptor motifs and receptor binding to the enhancer as we show using ChIP-seq, but appears to rely on motifs for other factors, including Eip74. Our strategy is applicable to study signal-dependent enhancers for different pathways and across organisms. STARR-seq was performed in S2 and OSC cells treated with ecdysone in two replicates. DHS-seq before and after treatment was done with single-end sequencing in two replicates. RNA-seq (with and without ecdysone) was performed with a strand-specific protocol using single-end sequencing in two replicates in S2. ChIP-seq (with and without ecdysone) was performed single-end sequencing in two replicates in S2 cells.
Project description:Cockayne syndrome is an inherited premature aging syndrome associated with developmental and neurological disorders. Mutations in the genomic locus encoding CSB are associated with 80% Cockayne syndrome cases. Transcription profiling assays reveal the association of mis-regulation of gene expression with Cockayne syndrome, highlighting the importance of CSB in transcription regulation. However, many questions remain unanswered as how CSB regulates transcription. In this study, we dissect the mechanisms by which CSB regulates transcription during normal growth. By anti-CSB chromatin immunoprecipitation followed by deep sequencing, we found CSB is enriched at genomic regions containing TGASTCA motifs, to which the immediate early gene product C-Jun binds specifically. We further demonstrate that c-Jun co-immunoprecipitates with CSB. In addition, the targeting of CSB to genomic region containing TGASTCA motifs was drastically reduced in cells treated c-Jun shRNA. Reverse transcription followed by quantitative PCR indicates that CSB can regulate gene expression nearby its binding sites, both in activation and repression. The remodeling defective CSBM-bM-^HM-^FN1 mutant is also targeted to TGASTCA motifs, but cannot always substitute CSB function in transcription regulating, suggesting the importance of remodeling by CSB in transcription regulation. Notably, the Cockayne syndrome related mutation encoding protein CSBR670W, which is defective in ATP hydrolysis but is targeted to TGASTCA motifs efficiently, indicating that ATP hydrolysis is dispensable for c-Jun mediated CSB targeting, in sharp contrast to the ATP-dependent targeting mechanism by which CSB is relocated to DNA lesion stalled transcription. Together, these results reveal a second CSB targeting mechanism in which DNA sequence specific transcription factor c-Jun targets CSB to specific genomic region and regulate gene expression. Genomic localization of CSB and remodeling deficient CSBM-bM-^HM-^FN1
Project description:Epigenetic mechanisms set apart the active and inactive regions in the genome of multicellular organisms to produce distinct cell fates during embryogenesis. Here, we report on the epigenetic and transcriptome genome-wide maps of gastrula-stage Xenopus tropicalis embryos using massive parallel sequencing of cDNA (RNA-seq) and DNA obtained by chromatin immunoprecipitation (ChIP-seq) of histone H3 K4 and K27 trimethylation and RNA Polymerase II (RNAPII). These maps identify promoters and transcribed regions. Strikingly, genomic regions featuring opposing histone modifications are mostly transcribed, reflecting spatially regulated expression rather than bivalency as determined by expression profile analyses, sequential ChIP, and ChIP-seq on dissected embryos. Spatial differences in H3K27me3 deposition are predictive of localized gene expression. Moreover, the appearance of H3K4me3 coincides with zygotic gene activation, whereas H3K27me3 is predominantly deposited upon subsequent spatial restriction or repression of transcriptional regulators. These results reveal a hierarchy in the spatial control of zygotic gene activation. ChIP-seq profiles of two histone modifications (H3K4me3 and H3K27me3) and RNA Polymerase II, and a RNA-seq profile, of gastrula stage Xenopus tropicalis embryos
Project description:Virtually all living organisms are challenged by changes in their environment, such as sudden increases in osmolarity. To survive, cells have developed stress-responsive mechanisms that tune functions such as metabolism and gene expression. The response of Saccharomyces cerevisiae to osmostress includes a massive reprogramming of gene expression. Identifying the inherent features of stress-responsive genes is of significant interest for understanding the basic principles underlying the rewiring of gene expression upon stress. Here we generated a comprehensive catalog of osmotress-responsive genes from 5 independent RNA-seq experiments. We explored 30 features of yeast genes and found that 25 (83.34%) were distinct in osmostress-responsive genes. We then identified a subset of 13 non-redundant minimal osmostress gene traits and used statistical modeling to generate a ranking of the most stress-predictive features. Our findings reveal that the most relevant features of osmostress-responsive genes are the number of transcription factors targeting a gene and gene conservation. The same features that define yeast osmostress-responsive genes can also be used to predict osmostress-responsive genes in humans, although the most predictive features in humans are GC content and mRNA half-life. Our study provides a holistic understanding of the basic principles of the regulation of stress-responsive gene expression across eukaryotes.
Project description:This SuperSeries is composed of the SubSeries listed below. This dataset is part of a larger study, entitled “Widespread epigenetic changes to the enhancer landscape of mouse liver induced by a specific xenobiotic agonist ligand of the nuclear receptor CAR”, which found that active enhancer and promoter histone marks induced by TCPOBOP were enriched at opening DNase hypersensitive sites (DHS) and TCPOBOP-inducible genes. Enrichment of CAR binding and CAR motifs was seen at opening DHS and their inducible drug/lipid metabolism gene targets, and at many constitutively open DHS located nearby. TCPOBOP-responsive cell cycle and DNA replication genes co-dependent on MET/EGFR signaling for induction were also enriched for CAR binding. A subset of opening DHS and many closing DHS mapping to TCPOBOP-responsive target genes did not bind CAR, indicating an indirect mechanism for their changes in chromatin accessibility. TCPOBOP-responsive DHS were also enriched for induced binding of RXRA, CEBPA and CEBPB, and for motifs for liver-enriched factors that may contribute to liver-specific transcriptional responses to TCPOBOP exposure. These studies elucidate the enhancer landscape of TCPOBOP-exposed liver and the widespread epigenetic changes that are induced by both direct and indirect mechanisms linked to CAR activation.
Project description:Cockayne syndrome is an inherited premature aging syndrome associated with developmental and neurological disorders. Mutations in the genomic locus encoding CSB are associated with 80% Cockayne syndrome cases. Transcription profiling assays reveal the association of mis-regulation of gene expression with Cockayne syndrome, highlighting the importance of CSB in transcription regulation. However, many questions remain unanswered as how CSB regulates transcription. In this study, we dissect the mechanisms by which CSB regulates transcription during normal growth. By anti-CSB chromatin immunoprecipitation followed by deep sequencing, we found CSB is enriched at genomic regions containing TGASTCA motifs, to which the immediate early gene product C-Jun binds specifically. We further demonstrate that c-Jun co-immunoprecipitates with CSB. In addition, the targeting of CSB to genomic region containing TGASTCA motifs was drastically reduced in cells treated c-Jun shRNA. Reverse transcription followed by quantitative PCR indicates that CSB can regulate gene expression nearby its binding sites, both in activation and repression. The remodeling defective CSB∆N1 mutant is also targeted to TGASTCA motifs, but cannot always substitute CSB function in transcription regulating, suggesting the importance of remodeling by CSB in transcription regulation. Notably, the Cockayne syndrome related mutation encoding protein CSBR670W, which is defective in ATP hydrolysis but is targeted to TGASTCA motifs efficiently, indicating that ATP hydrolysis is dispensable for c-Jun mediated CSB targeting, in sharp contrast to the ATP-dependent targeting mechanism by which CSB is relocated to DNA lesion stalled transcription. Together, these results reveal a second CSB targeting mechanism in which DNA sequence specific transcription factor c-Jun targets CSB to specific genomic region and regulate gene expression.
Project description:Epigenetic mechanisms set apart the active and inactive regions in the genome of multicellular organisms to produce distinct cell fates during embryogenesis. Here, we report on the epigenetic and transcriptome genome-wide maps of gastrula-stage Xenopus tropicalis embryos using massive parallel sequencing of cDNA (RNA-seq) and DNA obtained by chromatin immunoprecipitation (ChIP-seq) of histone H3 K4 and K27 trimethylation and RNA Polymerase II (RNAPII). These maps identify promoters and transcribed regions. Strikingly, genomic regions featuring opposing histone modifications are mostly transcribed, reflecting spatially regulated expression rather than bivalency as determined by expression profile analyses, sequential ChIP, and ChIP-seq on dissected embryos. Spatial differences in H3K27me3 deposition are predictive of localized gene expression. Moreover, the appearance of H3K4me3 coincides with zygotic gene activation, whereas H3K27me3 is predominantly deposited upon subsequent spatial restriction or repression of transcriptional regulators. These results reveal a hierarchy in the spatial control of zygotic gene activation.
Project description:Chromatin immunoprecipitation and sequencing for the H3K27me3 histone mark was performed on livers of male mice either treated with vehicle or with TCPOBOP for 27 h. This dataset is part of a larger study, entitled “Widespread epigenetic changes to the enhancer landscape of mouse liver induced by a specific xenobiotic agonist ligand of the nuclear receptor CAR”, which found that active enhancer and promoter histone marks induced by TCPOBOP were enriched at opening DNase hypersensitive sites (DHS) and TCPOBOP-inducible genes. Enrichment of CAR binding and CAR motifs was seen at opening DHS and their inducible drug/lipid metabolism gene targets, and at many constitutively open DHS located nearby. TCPOBOP-responsive cell cycle and DNA replication genes co-dependent on MET/EGFR signaling for induction were also enriched for CAR binding. A subset of opening DHS and many closing DHS mapping to TCPOBOP-responsive target genes did not bind CAR, indicating an indirect mechanism for their changes in chromatin accessibility. TCPOBOP-responsive DHS were also enriched for induced binding of RXRA, CEBPA and CEBPB, and for motifs for liver-enriched factors that may contribute to liver-specific transcriptional responses to TCPOBOP exposure. These studies elucidate the enhancer landscape of TCPOBOP-exposed liver and the widespread epigenetic changes that are induced by both direct and indirect mechanisms linked to CAR activation.
Project description:Chromatin immunoprecipitation and sequencing for the H3K27me3 histone mark was performed on livers of male mice either treated with vehicle or with TCPOBOP for 3 h. This dataset is part of a larger study, entitled “Widespread epigenetic changes to the enhancer landscape of mouse liver induced by a specific xenobiotic agonist ligand of the nuclear receptor CAR”, which found that active enhancer and promoter histone marks induced by TCPOBOP were enriched at opening DNase hypersensitive sites (DHS) and TCPOBOP-inducible genes. Enrichment of CAR binding and CAR motifs was seen at opening DHS and their inducible drug/lipid metabolism gene targets, and at many constitutively open DHS located nearby. TCPOBOP-responsive cell cycle and DNA replication genes co-dependent on MET/EGFR signaling for induction were also enriched for CAR binding. A subset of opening DHS and many closing DHS mapping to TCPOBOP-responsive target genes did not bind CAR, indicating an indirect mechanism for their changes in chromatin accessibility. TCPOBOP-responsive DHS were also enriched for induced binding of RXRA, CEBPA and CEBPB, and for motifs for liver-enriched factors that may contribute to liver-specific transcriptional responses to TCPOBOP exposure. These studies elucidate the enhancer landscape of TCPOBOP-exposed liver and the widespread epigenetic changes that are induced by both direct and indirect mechanisms linked to CAR activation.