A new model for long-range chromatin reorganisation linked to enhancer activation [ChIP-chip]
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE115642 | GEO | 2018/12/01
REPOSITORIES: GEO
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Project description:Enhancers are fundamental to gene regulation. Post-translational modifications by the small ubiquitin-like modifiers (SUMO) modify chromatin regulation enzymes, including histone acetylases and deacetylases. However, it remains unclear whether SUMOylation regulates enhancer marks, acetylation at the 27th lysine residue of the histone H3 protein (H3K27Ac). We hypothesize that SUMOylation regulates H3K27Ac. To test this hypothesis, we performed genome-wide ChIP-seq analyses. We discovered that knockdown (KD) of the SUMO activating enzyme catalytic subunit UBA2 reduced H3K27Ac at most enhancers. Bioinformatic analysis revealed that TFAP2C-binding sites are enriched in enhancers whose H3K27Ac was reduced by UBA2 KD. ChIP-seq analysis in combination with molecular biological methods showed that TFAP2C binding to enhancers increased upon UBA2 KD or inhibition of SUMOylation by a small molecule SUMOylation inhibitor. However, this is not due to the SUMOylation of TFAP2C itself. Proteomics analysis of TFAP2C interactome on the chromatin identified histone deacetylation (HDAC) machinery. TFAP2C KD reduced HDAC binding to chromatin and increased H3K27Ac marks at enhancer regions, suggesting that TFAP2C is involved in recruiting HDAC. Taken together, our findings provide important insights into regulation of enhancer marks by SUMOylation.
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Project description:A novel long-range enhancer for Shh - Shh-Brain-Enhancer-6 (SBE6) – that is located 100kb upstream of Shh and that is required for the proper induction of Shh expression during neural differentiation ChIP-on-chip for H3K4me1 and H3K27ac in ESCs and NPCs showed a gain of these two enhancer marks in NPCs at SBE6 which identified this sequence as having potential enhancer activity.
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Project description:Enhancers play key roles in gene regulation. However, comprehensive enhancer discovery is challenging because most enhancers, especially those affected in complex diseases, have weak effects on gene expression. Through gene regulatory network modeling, we identified that dynamic cell state transitions, a critical missing component in prevalent enhancer discovery strategies, can be utilized to improve the cells’ sensitivity to enhancer perturbation. Guided by the modeling results, we performed a mid-transition CRISPRi-based enhancer screen utilizing human embryonic stem cell definitive endoderm differentiation as a dynamic transition system. The screen discovered a comprehensive set of enhancers (4 to 9 per locus) for each of the core lineage-specifying transcription factors (TFs), including many enhancers with weak to moderate effects. Integrating the screening results with enhancer activity measurements (ATAC-seq, H3K27ac ChIP-seq) and three-dimensional enhancer-promoter interaction information (CTCF looping, Hi-C), we were able to develop a CTCF loop-constrained Interaction Activity (CIA) model that can better predict functional enhancers compared to models that rely on Hi-C-based enhancer-promoter contact frequency. Together, our dynamic network-guided enhancer screen and the CIA enhancer prediction model provide generalizable strategies for sensitive and more comprehensive enhancer discovery in both normal and pathological cell state transitions.
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Project description:The pluripotency of embryonic stem cells (ESCs) is maintained by a small group of master transcription factors including Oct4, Sox2 and Nanog. These core factors form a regulatory circuit controlling the transcription of a number of pluripotency factors including themselves. Although a lot of previous studies have identified key factors regulating this core network in trans, the contribution of cis-regulatory DNA sequences on the transcription of these key pluripotency factors remains elusive. We analyzed epigenomic data within the 1.5 Mb gene-desert regions around Sox2 gene and predicted only one 13kb-long enhancer located 100kb downstream of Sox2 in mouse ES cells. This enhancer is occupied by Oct4, Sox2, Nanog, and mediator complex and forms a long-range DNA looping to Sox2 locus. We hypothesized that this enhancer is critical for Sox2 gene expression and tested this hypothesis by deleting this entire 13-kb enhancer with a simple highly-efficient double-excision CRISPR strategy. Allele-specific of Sox2 transcripts in heterozygous enhancer-deletion clones showed that the enhancer affects expression through a cis-acting mechanism. Strikingly, although this distal enhancer is not conserved in other mammals including human, it is responsible for over 90% of Sox2 expression in mouse ESCs. Taken together, our results provide direct evidence that in mouse ESCs, Sox2 transcription is primarily driven by a species-specific distal enhancer, which may provide new perspectives explaining the physiological difference between human and mouse ES cells. This dataset include ChIP-seq of H3K4me3 and H3K27ac in a hybrid mouse ES cells (F123). H3K27ac in J1 mouse ES cells. And RNA-seq in F123 mESCs with complete Sox2 enhancer deletion or enhancer haploinsufficient clones.
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Project description:The landscape of human epigenome undergoes extensive changes during development, leading to distinct transcription programs in different cell types. It is however still not clear how the high-order genome organization reshapes in cellular differentiation. Using Hi-C, we compared the comprehensive 3D genome maps in human embryonic stem cells (ESCs) and two differentiated cell types at kilobase resolution. Consistent with previous reports, we found that the CTCF protein anchors long-range constitutive interactions that are invariant between different cell types. The most stable DNA contacts in ESC are between a few hundred genomic loci with strongest histone H3 lysine 27 tri-methylation (H3K27me3) binding, which plays a key role maintaining pluripotency by inhibiting key development genes. These repressive 3D chromatin structures are resolved in differentiated cells, accompanied by redistribution of H3K27me3 mark. Most surprisingly, we found that in human ESCs, DNA looping interactions are not enriched at enhancers, suggesting a stochastic nature of DNA looping interactions at ESC enhancers. This is in sharp contrast to differentiated cells, in which a majority of cell type specific DNA looping interactions are at enhancers, regardless of whether the enhancers are co-occupied by CTCF. Taken together, our analysis revealed a primitive enhancer-independent genome architecture in ESCs, which is consistent with the stem cell pluripotency and differentiation plasticity. Most of the stable DNA looping interactions associated with lineage-governing enhancers are created only during cell fate commitment.
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Project description:Super-enhancers are large clusters of transcriptional enhancers that drive expression of genes that control and define cell identity. Improved understanding of the roles super-enhancers play in biology would be afforded by knowing the constellation of factors that constitute these domains and by identifying super-enhancers across the spectrum of human cell types. We describe here the population of transcription factors, cofactors, chromatin regulators and core transcription apparatus that occupy super-enhancers in embryonic stem cells (ESCs) and evidence that super-enhancers are highly transcribed. We then use epigenomic data to produce a catalogue of super-enhancers in a broad range of human cell types. These super-enhancer domains are associated with genes encoding master transcription factors and other components that play important roles in the biology of these cells. Interestingly, sequence variation associated with a broad spectrum of diseases is especially enriched in the super-enhancers of disease-relevant cell types. Furthermore, we find that cancer cells generate super-enhancers at oncogenes and other genes that play important roles in tumor pathogenesis. We discuss these insights and their implications for future study of human health and disease. ChIP-Seq for transcription factors in mouse embryonic stem cells and H3K27ac in Jurkat T-ALL cell line RNA-Seq for mouse embryonic stem cells
2013-10-23 | E-GEOD-51522 | biostudies-arrayexpress
Project description:The functional importance of gene enhancers in regulated gene expression is well established. In addition to widespread transcription of long non-coding RNA (ncRNA) transcripts in mammalian cells, bidirectional ncRNAs referred to as eRNAs are present on enhancers. However, it has remained unclear whether these eRNAs are functional, or merely a reflection of enhancer activation. Here, we report that 17 ?-estradiol (E2)-bound estrogen receptor alpha (ER?) on enhancers causes a global increase in eRNA transcription on enhancers adjacent to E2 upregulated coding genes. These induced eRNAs, as functional transcripts, appear to exert important roles for the observed ligand-dependent induction of target coding genes, causing an increased strength of specific enhancer:promoter looping initiated by ER? binding. Cohesin, present on many ER?-regulated enhancers even prior to ligand treatment, apparently contributes to E2-dependent gene activation by stabilizing E2/ER?/eRNA-induced enhancer:promoter looping. Our data indicate that eRNAs are likely to exert important functions in many regulated programs of gene transcription. The ChIP-seqs in this study measure the binding landscape of master transcription regulator of estrogen signaling - ER?, together with common histone marks including H3K27ac and H3K4me1 in MCF7 cells. These data serve as the basis to understand the enhancer map and subsequent analysis of eRNA expression using GRO-seq. The GRO-seq measures the trancription of nascent RNAs in the genome. From MCF7 cells treated with veichle or estrodial, we could identify estrogen-regulated eRNAs and subsequently could study their functions.
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