Anti-cancer drugs curaxins target the 3D genome organization [ChIP-seq]
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE122462 | GEO | 2019/02/18
REPOSITORIES: GEO
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Project description:We have recently discovered a class of anti-cancer agents, curaxins, which suppress transcription of oncogenes. Here we demonstrate that curaxins preferentially downregulate expression of genes controlled by enhancers and super-enhancers via interrupting enhancer/promoter spatial communication. Our observations made both on a model of enhancer-regulated transcription of chromatinized template and on cultured cancer cells allow classifying curaxins as a novel type of epigenetic drugs that target the 3D genome organization.
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Project description:Much of mammalian physiology exhibits 24-hour cyclicity due to circadian rhythms of gene expression controlled by transcription factors (TF) that comprise molecular clocks. Core clock TFs bind to the genome at non-coding enhancer sequences to regulate circadian gene expression, but not all binding sites are equally functional. Here we demonstrate that circadian gene expression in mouse liver is controlled by rhythmic chromatin interactions between enhancers and promoters within topologically associating domains (TAD). Rev-erbα-, a core repressive TF of the clock, opposes functional loop formation between Rev-erbα-regulated enhancers and circadian target gene promoters by recruitment of the NCoR-HDAC3 corepressor complex, histone deacetylation, and eviction of the elongation factor BRD4 and the looping factor MED1. These loops are stronger and functionally active in the physiological or genetic absence of Rev-erbα.Thus, a repressive arm of the molecular clock operates by rhythmically interrupting enhancer-promoter loops to control circadian gene transcription.
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Project description:Here we apply integrated epigenomic and transcriptomic profiling to uncover super-enhancer heterogeneity between breast cancer subtypes, and provide clinically relevant biological insights towards TNBC. Using CRISPR/Cas9-mediated gene editing, we identify genes that are specifically regulated by TNBC-specific super-enhancers, including FOXC1 and MET, thereby unveiling a mechanism for specific overexpression of the key oncogenes in TNBC. We also identify ANLN as a novel TNBC-specific gene regulated by super-enhancer. Our studies reveal a TNBC-specific epigenomic landscape, contributing to the dysregulated oncogene expression in breast tumorigenesis.
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Project description:Polycomb repressive complex PRC1 is essential for gene regulation in numerous cell fate decisions. We show that RING1B (RING2, RNF2) and canonical PRC1 (cPRC1) genes are amplified and overexpressed in breast cancer (BC). Moreover, cPRC1 complexes functionally associate with genes regulated by cell type specific key transcription factors such as estrogen receptor (ER) in ER+ tumor cells and BRD4 in triple negative BC cells. cPRC1 is recruited to active enhancers in a manner independent of PRC2 and RING1B enzymatic activity. RING1B regulates enhancer activity and gene transcription not only by promoting the expression of BC oncogenes but also by regulating chromatin accessibility for oncogenic transcription factors. RING1B recruitment, and thus PRC1 association, to active enhancers occurs in multiple cancers.
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Project description:Recent epigenomic studies have predicted thousands of potential enhancers in the human genome. However, there has not been systematic characterization of target promoters for these potential enhancers. Using H3K4me2 as a mark for active enhancers, we identified genome-wide enhancer-promoter interactions in human CD4+ T cells. Among the 6,520 long-distance chromatin interactions, we identify 2,067 enhancers that interact with 1,619 promoters and enhance their expression. These enhancers exist in accessible chromatin regions and are associated with various histone modifications and Pol II binding. The promoters with interacting enhancers are expressed at higher levels than those without interacting enhancers and their expression levels are positively correlated with the number of interacting enhancers. Interestingly, interacting promoters are co-expressed in a tissue-specific manner. We also find that chromosomes are organized into multiple levels of interacting domains. Our results define a global view of enhancer-promoter interactions and provide a dataset to further understand mechanisms of enhancer targeting and long-range chromatin organization. Two biological replicates of ChIA-PET (Chromatin Interaction Analysis by Paired-End Tag Sequencing) experiment in CD4+ T cells
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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:Cell fate transitions are accompanied by global transcriptional, epigenetic and topological changes driven by transcription factors (TFs), as is strikingly exemplified by reprogramming somatic cells to pluripotent stem cells (PSCs) via expression of OCT4, KLF4, SOX2 and cMYC. How TFs orchestrate the complex molecular changes around their target gene loci in a temporal manner remains incompletely understood. Here, using KLF4 as a paradigm, we provide the first TF-centric view of chromatin reorganization and its association to 3D enhancer rewiring and transcriptional changes of linked genes during reprogramming of mouse embryonic fibroblasts (MEFs) to PSCs. Inducible depletion of KLF factors in PSCs caused a genome-wide decrease in the connectivity of enhancers, while disruption of individual KLF4 binding sites from PSC-specific enhancers was sufficient to impair enhancer-promoter contacts and reduce expression of associated genes. Our study provides an integrative view of the complex activities of a lineage-specifying TF during a controlled cell fate transition and offers novel insights into the order and nature of molecular events that follow TF binding.
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Project description:<p>Metabolic lesions with pleiotropic effects on epigenetic regulation and other cellular processes are widely implicated in cancer, yet their oncogenic mechanisms remain poorly understood. Succinate dehydrogenase (SDH) deficiency causes a subset of gastrointestinal stromal tumors (GISTs) with DNA hyper-methylation. Here we associate this hyper-methylation with changes in chromosome topology that activate oncogenic programs. To investigate epigenetic alterations in this disease, we systematically mapped DNA methylation, CTCF insulators, enhancers and chromosome topology in KIT-mutant, PDGFRA-mutant and SDH-deficient GISTs. Although these respective subtypes share similar enhancer landscapes, we identified hundreds of putative insulators where DNA methylation replaced CTCF binding in SDH-deficient GISTs. We focused on disrupted insulators that partitions super-enhancers from FGF3, FGF4 and the KIT oncogene. Recurrent loss of this insulator alters locus topology in SDH-deficient GISTs, allowing aberrant physical interaction between enhancers and oncogenes. CRISPR-mediated excision of the corresponding CTCF motif in an SDH-intact model disrupted the boundary and up-regulated FGFs and KIT expression. Our findings reveal how a metabolic lesion destabilizes chromatin structure to facilitate the initiation and selection of epigenetic alterations that drive oncogenic programs in the absence of canonical mutations.</p>
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Project description:Enhancer hijacking, caused by structural alterations, is a common cancer driver event that causes aberrant expression of oncogenes. Unfortunately, enhancer hijacking is difficult to detect due to the complexity of the cancer genome. Here we propose a simple yet robust strategy HAPI (Highly Active Promoter Interactions) to identify and characterize such events by following two rules: 1) oncogenes subject to enhancer hijacking should be potentially highly regulated by enhancers, 2) the hijacked enhancers should contribute an appreciable proportion of an oncogene’s overall enhancer activity. Applying this strategy to HiChIP data we and others generated in 34 cancer cell lines, we identified known enhancer hijacking events and uncovered novel enhancers hijacked by known or potentially novel oncogenes such as CCND1, ETV1, ID4, and NKX2-5, which we validated using CRISPRi assays and RNA-seq analysis. Furthermore, we found that complex enhancer hijacking events connecting genes and enhancers from multiple chromosomal segments are often caused by the formation of extrachromosomal circular DNA (ecDNA). Focusing on ecDNAs harboring the MYC oncogene, one of the most common gene targets of ecDNA, we found that these ecDNAs often stitch additional genes such as CDX2, ERBB2, and NFIB from other chromosomes to the MYC locus. These genes heavily hijack MYC enhancers for their activation, a novel insight into ecDNA biology, suggesting alternative therapeutic targets for MYC ecDNAs. Our study provides an efficient strategy to detect enhancer hijacking events, and more importantly reveals novel mechanisms underlying oncogene activation caused by simple or complex structural alterations.
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Project description:Enhancer hijacking, caused by structural alterations, is a common cancer driver event that causes aberrant expression of oncogenes. Unfortunately, enhancer hijacking is difficult to detect due to the complexity of the cancer genome. Here we propose a simple yet robust strategy HAPI (Highly Active Promoter Interactions) to identify and characterize such events by following two rules: 1) oncogenes subject to enhancer hijacking should be potentially highly regulated by enhancers, 2) the hijacked enhancers should contribute an appreciable proportion of an oncogene’s overall enhancer activity. Applying this strategy to HiChIP data we and others generated in 34 cancer cell lines, we identified known enhancer hijacking events and uncovered novel enhancers hijacked by known or potentially novel oncogenes such as CCND1, ETV1, ID4, and NKX2-5, which we validated using CRISPRi assays and RNA-seq analysis. Furthermore, we found that complex enhancer hijacking events connecting genes and enhancers from multiple chromosomal segments are often caused by the formation of extrachromosomal circular DNA (ecDNA). Focusing on ecDNAs harboring the MYC oncogene, one of the most common gene targets of ecDNA, we found that these ecDNAs often stitch additional genes such as CDX2, ERBB2, and NFIB from other chromosomes to the MYC locus. These genes heavily hijack MYC enhancers for their activation, a novel insight into ecDNA biology, suggesting alternative therapeutic targets for MYC ecDNAs. Our study provides an efficient strategy to detect enhancer hijacking events, and more importantly reveals novel mechanisms underlying oncogene activation caused by simple or complex structural alterations.
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