Identification of cancer drivers at CTCF insulators in 1,962 whole-genomes
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA527205 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR8732212.fastq.gz | Fastqsanger.gz | |||
| SRR8732213.fastq.gz | Fastqsanger.gz | |||
| SRR8732214.fastq.gz | Fastqsanger.gz | |||
| SRR8732215.fastq.gz | Fastqsanger.gz |
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Project description:We report the genome wide CTCF binding sites in the human melanoma A375 cell line.
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Project description:Recent studies have shown that mutations at non-coding elements, such as promoters and enhancers, can act as cancer drivers. However, an important class of non-coding elements, namely CTCF insulators, has been overlooked in the previous driver analyses. We used insulator annotations from CTCF and cohesin ChIA-PET and analyzed somatic mutations in 1,962 whole genomes from 21 cancer types. Using the heterogeneous patterns of transcription-factor-motif disruption, functional impact, and recurrence of mutations, we developed a computational method that revealed 21 insulators showing signals of positive selection. In particular, mutations in an insulator in multiple cancer types, including 16% of melanoma samples, are associated with TGFB1 up-regulation. Using CRISPR-Cas9, we find that alterations at two of the most frequently mutated regions in this insulator increase cell growth by 40%-50%, supporting the role of this boundary element as a cancer driver. Thus, our study reveals several CTCF insulators as putative cancer drivers.
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Project description:CTCF is a key insulator-binding protein and mammalian genomes contain numerous CTCF-binding sites (CBSs), many of which are organized in tandem arrays. Here we provide direct evidence that CBSs, if located between enhancers and promoters in the clustered Pcdh and b-globin clusters, function as an enhancer-blocking insulator by forming distinct directional chromatin loops, regardless whether enhancers contain CBS or not. Moreover, computational simulation and experimental capture revealed balanced promoter usage in vivo in cell populations and stochastic monoallelic expression in single cells by large arrays of tandem variable CBSs. Finally, gene expression levels are negatively correlated with CBS insulators located between enhancers and promoters on a genome-wide scale. Thus, single CBS insulators ensure proper enhancer insulation and promoter activation while tandem-arrayed CBS insulators determine balanced promoter choice. This finding has interesting implications on the role of topological insulators in 3D genome folding and developmental gene regulation.
2020-03-01 | GSE135394 | GEO
Project description:CTCF is a key insulator-binding protein and mammalian genomes contain numerous CTCF-binding sites (CBSs), many of which are organized in tandem arrays. Here we provide direct evidence that CBSs, if located between enhancers and promoters in the clustered Pcdh and b-globin clusters, function as an enhancer-blocking insulator by forming distinct directional chromatin loops, regardless whether enhancers contain CBS or not. Moreover, computational simulation and experimental capture revealed balanced promoter usage in vivo in cell populations and stochastic monoallelic expression in single cells by large arrays of tandem variable CBSs. Finally, gene expression levels are negatively correlated with CBS insulators located between enhancers and promoters on a genome-wide scale. Thus, single CBS insulators ensure proper enhancer insulation and promoter activation while tandem-arrayed CBS insulators determine balanced promoter choice. This finding has interesting implications on the role of topological insulators in 3D genome folding and developmental gene regulation.
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Project description:CTCF is a key insulator-binding protein and mammalian genomes contain numerous CTCF-binding sites (CBSs), many of which are organized in tandem arrays. Here we provide direct evidence that CBSs, if located between enhancers and promoters in the clustered Pcdh and b-globin clusters, function as an enhancer-blocking insulator by forming distinct directional chromatin loops, regardless whether enhancers contain CBS or not. Moreover, computational simulation and experimental capture revealed balanced promoter usage in vivo in cell populations and stochastic monoallelic expression in single cells by large arrays of tandem variable CBSs. Finally, gene expression levels are negatively correlated with CBS insulators located between enhancers and promoters on a genome-wide scale. Thus, single CBS insulators ensure proper enhancer insulation and promoter activation while tandem-arrayed CBS insulators determine balanced promoter choice. This finding has interesting implications on the role of topological insulators in 3D genome folding and developmental gene regulation.
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Project description:CTCF is a key insulator-binding protein and mammalian genomes contain numerous CTCF-binding sites (CBSs), many of which are organized in tandem arrays. Here we provide direct evidence that CBSs, if located between enhancers and promoters in the clustered Pcdh and b-globin clusters, function as an enhancer-blocking insulator by forming distinct directional chromatin loops, regardless whether enhancers contain CBS or not. Moreover, computational simulation and experimental capture revealed balanced promoter usage in vivo in cell populations and stochastic monoallelic expression in single cells by large arrays of tandem variable CBSs. Finally, gene expression levels are negatively correlated with CBS insulators located between enhancers and promoters on a genome-wide scale. Thus, single CBS insulators ensure proper enhancer insulation and promoter activation while tandem-arrayed CBS insulators determine balanced promoter choice. This finding has interesting implications on the role of topological insulators in 3D genome folding and developmental gene regulation.
2020-03-01 | GSE139679 | GEO
Project description:Long-range transcriptional activation of gene promoters by abundant enhancers in animal genomes raises the need for mechanisms to limit inappropriate gene regulation. DNA elements known as insulators provide one such mechanism by shielding promoters from an enhancer when placed in between these two elements. Whereas promoters and enhancers have been extensively characterized in animal genomes, insulators have not because of the lack of a high-throughput screening assay. In the absence of unbiased insulator screening in a genome, basic questions remain about the identity, density and diversity of genomic insulators. Here, we establish “insulator-seq” as a plasmid-based massively parallel reporter assay in Drosophila tissue culture cells to perform the first unbiased screen for insulators in any genome. By screening developmental gene loci, we found that not all characterized insulator protein binding sites are able to block enhancer-promoter communication. By dissecting the sequence determinants of functional insulators, we found that an unexpectedly broad sequence context around the central insulator protein binding motif is required for functionality. The ability to screen millions of DNA sequences in parallel without any positional effect has enabled the first functional mapping of insulators and provided further insights into the determinants of functional insulators.
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Project description:Insulators are DNA elements, which prevent inappropriate interactions between the neighboring regions of the genome. They can be functionally classified as either enhancer blockers or domain barriers. CTCF (CCCTC binding factor) is the only known major insulator binding protein in the vertebrates and has been shown to bind many enhancer-blocking elements. However, it is not clear whether it plays a role in chromatin domain barriers between active and repressive domains. Here, we used ChIP-Seq to map the genome-wide binding sites of CTCF in three cell types and identified significant binding of CTCF to the boundaries of repressive chromatin domains marked by H3K27me3. Although we find an extensive overlapping of CTCF binding sites across the three cell types, its association with the domain boundaries is cell type-specific. We further show that the nucleosomes flanking CTCF binding sites are well positioned and associated with histone H2AK5 acetylation (H2AK5ac). Interestingly, we found a complementary pattern between the repressive H3K27me3 and the active H2AK5ac regions, which are separated by CTCF. Our findings indicate that CTCF may play important roles in the barrier activity of insulators and provide a resource for further investigation of the CTCF function in organizing chromatin in the human genome. Examination of the role of CTCF in chromatin domain barrier function In addition to the ChIP-seq analysis, two replicates of HeLa expression data were studied.
2008-10-20 | E-GEOD-12889 | biostudies-arrayexpress
Project description:Insulators are an important class of transcriptional regulatory sequences that affect gene expression by preventing the spread of heterochromatin and restricting how transcriptional enhancers select their target genes. The vertebrate insulators function by interacting with the CCCTC-binding factor (CTCF), an evolutionarily conserved DNA binding protein. Knowledge of the CTCF binding sites in the human genome is crucial for identifying potential insulators and understanding the role of these elements in regulating genome expression in the human cells. Here, we report the identification and characterization of a large number of CTCF binding sites in the human genome. Using chromatin immunoprecipitation combined with high-resolution genome-tiling arrays, we have determined the locations of CTCF throughout the non-repetitive human DNA sequences, identifying 13,804 binding sites in the genome of human fibroblasts. Computational analysis of these sequences revealed a single dominant CTCF consensus motif that is shared by a vast majority of the CTCF binding sites and is highly conserved in other vertebrate genomes. The CTCF binding segments the human genome into 5,969 domains, which contain an average of 2.5 genes each. Many large gene families, such as the olfactory receptor genes, are bounded by the CTCF sites, implicating a role of CTCF in the regulation or evolution of these genes. We demonstrate that CTCF binding can occur in a cell type dependent manner, and that binding of CTCF between two neighboring genes coincides with a loss of coordinated expression, consistent with their role as insulators. Our results provide a general resource and framework for analyzing the role of CTCF and insulator elements in the regulation of nearly every gene in the human genome. Keywords: ChIP-chip
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Project description:The human genome is folded into regulatory units termed ‘topologically-associated domains’ (TADs), within which the majority of gene-enhancer interactions occur. Genome-wide studies support a global role for the insulator protein CTCF in mediating chromosomal looping and the topological constraint of TAD boundaries3,4. However, the impact of individual insulators on enhancer-gene interactions and transcription remains poorly understood. Here, we investigate epigenome editing strategies for perturbing individual CTCF insulators and evaluating consequent effects on genome topology and transcription. We show that fusions of catalytically-inactive Cas9 (dCas9) to transcriptional repressors (dCas9-KRAB) and DNA methyltransferases (dCas9-DNMT3A, dCas9-DNMT3A3L) can selectively displace CTCF from specific insulators, but only when precisely targeted to the cognate motif. We further demonstrate that stable, mitotically-heritable insulator disruption can be achieved through combinatorial hit-and-run epigenome editing with dCas9-KRAB and dCas9-DNMT3A3L. Finally, we apply these strategies to activate PDGFRA expression in glioblastoma stem cells, thus simulating an insulator loss mechanism implicated in brain tumorigenesis. Our study provides strategies for stably modifying genome organization and gene activity without altering the underlying DNA sequence.
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