Chromatin interaction profiles at bivalent genes by multiplexed splinkerette 4C sequencing
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE90782 | GEO | 2017/11/04
SECONDARY ACCESSION(S): PRJNA355885
REPOSITORIES: GEO
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Project description:Regulatory decisions in Drosophila require Polycomb group (PcG) proteins to maintain the silent state and Trithorax group (TrxG) proteins to oppose silencing. Since PcG and TrxG are ubiquitous and lack apparent sequence specificity, a long-standing model is that targeting occurs via protein interactions; for instance, between repressors and PcG proteins. Instead, we found that Pc-repressive complex 1 (PRC1) purifies with coactivators Fs(1)h [female sterile (1) homeotic] and Enok/Br140 during embryogenesis. Fs(1)h is a TrxG member and the ortholog of BRD4, a bromodomain protein that binds to acetylated histones and is a key transcriptional coactivator in mammals. Enok and Br140, another bromodomain protein, are orthologous to subunits of a mammalian MOZ/MORF acetyltransferase complex. Here we confirm PRC1-Br140 and PRC1-Fs(1)h interactions and identify their genomic binding sites. PRC1-Br140 bind developmental genes in fly embryos, with analogous co-occupancy of PRC1 and a Br140 ortholog, BRD1, at bivalent loci in human embryonic stem (ES) cells. We propose that identification of PRC1-Br140 "bivalent complexes" in fly embryos supports and extends the bivalency model posited in mammalian cells, in which the coexistence of H3K4me3 and H3K27me3 at developmental promoters represents a poised transcriptional state. We further speculate that local competition between acetylation and deacetylation may play a critical role in the resolution of bivalent protein complexes during development.
2018-02-22 | GSE104059 | GEO
Project description:Background: Bivalent chromatin refers to overlapping regions containing activating histone H3 Lys4 trimethylation (H3K4me3) and inactivating H3K27me3 marks. Existence of such bivalent marks on the same nucleosome has only recently been suggested. Previous genome-wide efforts to characterize bivalent chromatin have focused primarily on individual marks to define overlapping zones of bivalency rather than mapping positions of truly bivalent mononucleosomes. Results: Here, we developed an efficacious sequential ChIP technique for examining global positioning of individual bivalent nucleosomes. Using next generation sequencing approaches we show that although individual H3K4me3 and H3K27me3 marks overlap in broad zones, bivalent nucleosomes are focally enriched in the vicinity of the transcription start site (TSS). These seem to occupy the H2A.Z nucleosome positions previously described as salt-labile nucleosomes, and are correlated with low gene expression. Although the enrichment profiles of bivalent nucleosomes show a clear dependency on CpG island content, they demonstrate a stark anti-correlation with methylation status. Conclusions: We show that regional overlap of H3K4me3 and H3K27me3 chromatin tend to be upstream to the TSS, while bivalent nucleosomes with both marks are mainly promoter proximal near the TSS of CpG island-containing genes with poised/low expression. We discuss the implications of the focal enrichment of bivalent nucleosomes around the TSS on the poised chromatin state of promoters in stem cells.
2016-09-13 | GSE86838 | GEO
Project description:The selective expression is pivotal in orchestrating human development, with the Trithorax Group (TrxG) and Polycomb Group (PcG) complexes playing crucial roles in transcriptional activation and repression, respectively. However, mechanism underlying selective regulation of transcription by TrxG and PcG remains poorly understood. In this study, RYBP was observed to interact with TrxG and PcG components. RYBP and TrxG co-localized loci selectively enriches RING1B. STAT3 enriches at RYBP-TrxG co-localized loci devoid of RING1B, while displaying minimal enrichment at RING1B-enrichred loci. Introduction of STAT3 at RYBP loci disrupted RING1B aggregation and chromatin binding. RYBP-deficiency impairs TrxG deposition at DNA repair genes in RYBP-TrxG loci, consequently diminishing their expression and inducing DNA damage. These results facilitate the transition of embryonic stem cells to 2-cell-like cells. Additionally, RYBP-deficiency attenuates PcG deposition at lineage-specific genes within RYBP-TrxG-RING1B loci, thereby promoting ESC differentiation. Collectively, these results provide novel insights into the selective regulation of gene expression.
2024-04-26 | GSE261485 | GEO
Project description:Bivalent domains marked with repressive H3K27me3 and activating H3K4me2/3 are a molecular signature of totipotency in stem cells and development. While bivalent domains are retained throughout the germline to recover totipotency in the next generation, the mechanisms establishing bivalent domains remains unknown. Here we demonstrate that a germline-specific Polycomb protein, SCML2, binds to chromatin containing hypomethylated DNA to induce H3K27me3, thereby initiating the establishment of germline-specific bivalent domains in mice. SCML2 regulates two distinct classes of autosomal bivalent domains, the first are maintained constitutively through spermatogenesis (Class I), and the second are specifically established during meiosis (Class II). In postmeiotic spermatids, the loss of H3K27me3 leads to an increase of H3K4me2/3 on bivalent domains and disorganization of pericentromic heterochromatin. We propose that SCML2 regulates dynamic bivalent domains in the germline as a molecular imprint to recover totipotency after fertilization.
2018-04-12 | GSE89502 | GEO
Project description:The bivalent domain at promoter region is a unique epigenetic feature poised for activation or repression during cell differentiation in embryonic stem cell. However, the function of bivalent domains in already differentiated cells remains exclusive. By profiling the epigenetic landscape of endothelial cells during VEGFA stimulation, we discovered that bivalent domains are widespread in endothelial cells and preferentially marked genes responsive to VEGFA. The bivalent domains responsive to VEGFA have more permissive chromatin environment comparing to other bivalent domains. The initial activation of bivalent genes depends on RNAPII pausing release induced by EZH1 rather than removal of H3K27me3. The later suppression of bivalent gene expression depended on KDM5A recruitment by its interaction with PRC2. Importantly, EZH1 promoted both in vitro and in vivo angiogenesis by upregulating EGR3, whereas KDM5A dampened angiogenesis. Collectively, this study demonstrated a novel dual function of bivalent domains in endothelial cells to control VEGF responsiveness and angiogenesis.
2020-10-17 | GSE139077 | GEO
Project description:A Trithorax-group (TrxG) protein ASH1 selectively dimethylates histone H3 lysine 36 (H3K36) and is required for expression of Hox genes. Genome-wide targets and molecular functions of ASH1, however, have remained elusive. Here we report ChIP-seq analysis of ASH1 targets in the human genome using a leukemia cell line K562. We identified 4,596 ASH1 binding sites, 2,502 of which are in the coding region, mostly in a proximity of promoters. Remaining half of the ASH1 binding sites are in the intergenic region. Analysis of histone methyation patterns revealed that a majority of ASH1 bidning sites are closely associated not only with trimethylated H3K36 (H3K36me3) but also with H3K9me3, shedding light for the first time to H3K36/H3K9 double methylation domains. Of note, an H3K9 methyltransferase SETDB1 is enriched in the ASH1 bidning sites, whereas EZH2 but not SUZ12 of the Polycomb Repression Complex 2 (PRC2) is present in bivalent domains. In addition, a small subset of ASH1 targets bear H3K4me3 and colocalize with RNA polymerase II. These select targets are highly enriched for regulators of gene expression, such as CXXC1, WHSC2/NELFA, and a battery of zinc finger proteins, suggesting that ASH1 might acts as a master regulator of gene expression.
2016-12-28 | GSE76145 | GEO
Project description:Background: The question of how cells re-establish gene expression states after cell division is still poorly understood. Genetic and molecular analyses have indicated that Trithorax group (TrxG) proteins are critical for the long-term maintenance of active gene expression states in many organisms. A generally accepted model suggests that TrxG proteins contribute to maintenance of transcription by protecting genes from inappropriate Polycomb group (PcG)-mediated silencing, instead of directly promoting transcription. Results: Here we report a physical and functional interaction in Drosophila between two members of the TrxG, the histone methyltransferase ASH1 and the bromodomain and extraterminal family protein FSH. We investigated this interface at the genome level, uncovering a widespread colocalization of both proteins at promoters and PcG-bound intergenic elements. Our integrative analysis of chromatin maps and gene expression profiles revealed that the observed ASH1-FSH binding pattern at promoters is a hallmark of active genes. Inhibition of FSH-binding to chromatin resulted in global down-regulation of transcription. In addition, we found that genes displaying marks of robust PcG-mediated repression also have ASH1 and FSH bound to their promoters. Conclusions: Our data strongly favor a global coactivator function of ASH1 and FSH during transcription, as opposed to the notion that TrxG proteins impede inappropriate PcG-mediated silencing, but are dispensable elsewhere. Instead, our results suggest that PcG repression needs to overcome the transcription-promoting function of ASH1 and FSH in order to silence genes. Refer to individual Series
2013-02-06 | E-GEOD-36450 | biostudies-arrayexpress
Project description:Identifying the molecular mechanisms by which genome-wide association study (GWAS) loci influence traits remains challenging. Chromatin accessibility quantitative trait loci (caQTL) help identify GWAS loci that may alter GWAS traits by modulating chromatin structure, but caQTL have been identified in a limited set of human tissues. Here we mapped caQTL in human liver tissue in 20 liver samples and identified 3,123 caQTL. The caQTL variants are enriched in liver tissue promoter and enhancer states and frequently disrupt binding motifs of transcription factors expressed in liver. We predicted target genes for 861 caQTL peaks using proximity, chromatin interactions, correlation with promoter accessibility or gene expression, and colocalization with expression QTL. Using GWAS signals for 19 liver function and/or cardiometabolic traits, we identified 110 colocalized caQTL and GWAS signals, 56 of which contained a predicted caPeak target gene. At the LITAF LDL-cholesterol GWAS locus, we validated that a caQTL variant showed allelic differences in protein binding and transcriptional activity. These caQTL contribute to the epigenomic characterization of human liver and help identify molecular mechanisms and genes at GWAS loci.
2021-05-01 | GSE164938 | GEO
Project description:Identifying the molecular mechanisms by which genome-wide association study (GWAS) loci influence traits remains challenging. Chromatin accessibility quantitative trait loci (caQTL) help identify GWAS loci that may alter GWAS traits by modulating chromatin structure, but caQTL have been identified in a limited set of human tissues. Here we mapped caQTL in human liver tissue in 20 liver samples and identified 3,123 caQTL. The caQTL variants are enriched in liver tissue promoter and enhancer states and frequently disrupt binding motifs of transcription factors expressed in liver. We predicted target genes for 861 caQTL peaks using proximity, chromatin interactions, correlation with promoter accessibility or gene expression, and colocalization with expression QTL. Using GWAS signals for 19 liver function and/or cardiometabolic traits, we identified 110 colocalized caQTL and GWAS signals, 56 of which contained a predicted caPeak target gene. At the LITAF LDL-cholesterol GWAS locus, we validated that a caQTL variant showed allelic differences in protein binding and transcriptional activity. These caQTL contribute to the epigenomic characterization of human liver and help identify molecular mechanisms and genes at GWAS loci.
2021-05-01 | GSE164876 | GEO
Project description:Identifying the molecular mechanisms by which genome-wide association study (GWAS) loci influence traits remains challenging. Chromatin accessibility quantitative trait loci (caQTL) help identify GWAS loci that may alter GWAS traits by modulating chromatin structure, but caQTL have been identified in a limited set of human tissues. Here we mapped caQTL in human liver tissue in 20 liver samples and identified 3,123 caQTL. The caQTL variants are enriched in liver tissue promoter and enhancer states and frequently disrupt binding motifs of transcription factors expressed in liver. We predicted target genes for 861 caQTL peaks using proximity, chromatin interactions, correlation with promoter accessibility or gene expression, and colocalization with expression QTL. Using GWAS signals for 19 liver function and/or cardiometabolic traits, we identified 110 colocalized caQTL and GWAS signals, 56 of which contained a predicted caPeak target gene. At the LITAF LDL-cholesterol GWAS locus, we validated that a caQTL variant showed allelic differences in protein binding and transcriptional activity. These caQTL contribute to the epigenomic characterization of human liver and help identify molecular mechanisms and genes at GWAS loci.
2021-05-01 | GSE164870 | GEO