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Single base-pair resolution analysis of binding motif with diffMotif uncovers the oncogenic impact of CTCF mutations in breast cancer [RNA-Seq]

ABSTRACT: Most cancer associated CTCF mutations are involved in the recognition of CTCF core binding motif. Interestingly, mutations of the currently uncharacterized ZF1 of CTCF are practically exclusive to breast cancer, where they are associated with increased metastatic ability and therapeutic resistance. Although unnecessary to bind the core-binding motif, it is still unknown if the ZF1 of CTCF promotes binding to an altered CTCF motif. Further, classical motif analysis tools are powerless to identify minute changes in core binding motif. Therefore, the biological and epigenetic mechanism of action of CTCF ZF1 mutations is still unexplored. In order to explain the impact of CTCF ZF1M in breast models, we developed a new tool, diffMotif, that allows the identification, at the single base-pair resolution, of extension or alteration of core binding motif. Using diffMotif, we identified an extension of CTCF core binding motif, necessitating a functional ZF1 to bind appropriately. Using a combination of ChIP-Seq and RNA-Seq, we discover that the inability to bind the extended motif led to altered gene expression driving increased invasive ability and drug metabolism, mimicking the harmful oncogenic phenotypes observed clinically. Our study demonstrates the oncologic relevance of the characterisation of mutation induced altered DNA binding ability, by diffMotif.

ORGANISM(S): Homo sapiens

PROVIDER: GSE190114 | GEO | 2022/06/28

REPOSITORIES: GEO

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Single base-pair resolution analysis of binding motif with diffMotif uncovers the oncogenic impact of CTCF mutations in breast cancer [ChIP-Seq]

Project description:Most cancer associated CTCF mutations are involved in the recognition of CTCF core binding motif. Interestingly, mutations of the currently uncharacterized ZF1 of CTCF are practically exclusive to breast cancer, where they are associated with increased metastatic ability and therapeutic resistance. Although unnecessary to bind the core-binding motif, it is still unknown if the ZF1 of CTCF promotes binding to an altered CTCF motif. Further, classical motif analysis tools are powerless to identify minute changes in core binding motif. Therefore, the biological and epigenetic mechanism of action of CTCF ZF1 mutations is still unexplored. In order to explain the impact of CTCF ZF1M in breast models, we developed a new tool, diffMotif, that allows the identification, at the single base-pair resolution, of extension or alteration of core binding motif. Using diffMotif, we identified an extension of CTCF core binding motif, necessitating a functional ZF1 to bind appropriately. Using a combination of ChIP-Seq and RNA-Seq, we discover that the inability to bind the extended motif led to altered gene expression driving increased invasive ability and drug metabolism, mimicking the harmful oncogenic phenotypes observed clinically. Our study demonstrates the oncologic relevance of the characterisation of mutation induced altered DNA binding ability, by diffMotif.

2022-06-28 | GSE190098 | GEO

RNA interactions are essential for proper CTCF function

Project description:The function of the CCCTC-binding factor (CTCF) in the organization of the genome has become an important area of investigation, but the mechanisms by which CTCF dynamically contributes to genome organization are not clear. We previously discovered that CTCF binds to large numbers of endogenous RNAs, promoting its self-association. In this regard, we now report two independent features that disrupt CTCF association with chromatin: inhibition of transcription and disruption of CTCF-RNA interactions through mutations of two of its 11 zinc fingers which are not required for CTCF binding to its cognate DNA site: zinc finger-1 (ZF1) or -10 (ZF10). These mutations alter gene expression profiles as CTCF mutants lose their ability to form chromatin loops and thus, the ability to insulate chromatin domains as well as mediate CTCF long-range genomic interactions. Our results point to the importance of CTCF-mediated RNA interactions as a structural component of genome organization.

2019-09-12 | GSE125595 | GEO

Atypical modes of CTCF binding facilitate tissue-specific and neuronal activity-dependent gene expression states [CTCF_ChIP-seq]

Project description:The multivalent binding of CTCF to a variety of DNA sequences is thought to underlie its ability to mediate a large repertoire of cellular functions. CTCF is a 11 zinc-finger (ZF) protein that is anchored to a majority of its target sites via binding to a 20 base-pair core DNA sequence. Yet the diversity of CTCF binding sites (CBS) has not fully been characterized. Here we assessed CTCF occupancy in cultured mouse cortical neurons as a function of neuronal activity and observed that ~ 22 % of CBS lack the consensus CTCF motif. We report that sequence diversity at most of these atypical CBS is not random but involves degeneracy at specific nucleotide positions within the core CTCF position weight matrix (PWM) that likely affect the binding of ZFs 6 and 7. Surprisingly, degeneracy at the same nucleotides not only define most atypical CBS, but also CBS within most gene promoters, and CBS that are dynamically altered following neuronal stimulation, revealing how atypical CTCF binding could affect gene activity. Dynamic CBS across neural differentiation and neuronal stimulation are found both within and outside loop anchors and TADs, indicating that dynamic CBS could regulate gene activity independently of loop anchoring. Finally, we identified a second mode of atypical CTCF binding that defines most tissue-specific CBS. Unlike other atypical CBS, tissue-specific CBS largely bind sequences unrelated to the core CTCF motif and are enriched within the bodies of tissue-specific genes. Overall, these results indicate how CTCF binding at atypical CBS could allow it to dynamically regulate gene activity patterns during differentiation, development, and in response to environmental cues.

2023-08-30 | GSE235970 | GEO

Atypical modes of CTCF binding facilitate tissue-specific and neuronal activity-dependent gene expression states [SMC1_ChIP-seq]

2023-08-30 | GSE235971 | GEO

The establishment of a CTCF activity reporter for systematic stratification of CTCF binding sites

Project description:While the elements encoding enhancers and promoters have been relatively well studied, the full spectrum of insulator elements which bind the CCCTC binding factor (CTCF), is relatively poorly characterised. In part, this is due the fact that their roles and activity is greatly influenced by their genomic context. Here we have developed an experimental system to determine the ability of consistently sized, individual CTCF elements to interpose between enhancers and promoters and thereby reduce gene expression during differentiation. Importantly each element is tested in the identical location thereby minimising the effect of genomic context. We found no correlation between the ability of CTCF elements to block enhancer-promoter activity with the amount of CTCF or cohesin bound at the natural genomic sites of these elements; the degree of evolutionary conservation; or their resemblance to the consensus core sequences. Nevertheless, we have shown that the strongest enhancer-promoter blockers include a previously described bound element lying upstream of the CTCF core motif. In addition, we found other uncharacterised DNAse1 footprints located close to the core sequence that may affect function. We have developed a high throughput assay of CTCF elements which will enable researchers to sub-classify CTCF elements in an unbiased way.

2023-08-12 | GSE240678 | GEO

Comparative analyses of CTCF and BORIS occupancies uncover two distinct classes of CTCF binding genomic regions

Project description:CTCF and BORIS (CTCFL), two paralogous mammalian proteins sharing nearly identical DNA binding domains, are thought to function in mutually exclusive manners in DNA binding and transcriptional regulation. Here we show that these two proteins co-occupy a specific subset of regulatory elements consisting of clustered CTCF binding motifs (termed 2xCTSes). BORIS occupancy at 2xCTSes is largely invariant in BORIS-positive cancer cells, with the genomic pattern recapitulating the germline-specific BORIS binding to chromatin. In contrast to the single-motif CTCF target sites (1xCTSes), the 2xCTS elements are preferentially found at active promoters and enhancers, both in cancer and germ cells. 2xCTSes are also enriched in genomic regions that escape histone to protamine replacement in human and mouse sperm. Depletion of BORIS gene leads to altered transcription of a large number of genes and the differentiation of K562 cells, while the ectopic expression of this CTCF paralog leads to specific changes in transcription in MCF7 cells. In summary, we discover two functionally and structurally different classes of CTCF binding regions, 2xCTSes and 1xCTSes, revealed by their predisposition to bind BORIS. We propose that 2xCTSes play key roles in the transcriptional program of cancer and germ cells Genome-wide mapping of CTCF and BORIS occupancies in both germ and cancer cells. ChIP-seq and expression profiling by high throughput sequencing

2015-07-23 | E-GEOD-70764 | biostudies-arrayexpress

Functional mutations form at CTCF-cohesin binding sites in melanoma due to uneven nucleotide excision repair across the motif

Project description:CTCF binding sites are frequently mutated in cancer, but how these mutations accumulate and whether they broadly perturb CTCF binding is not well understood. We report that skin cancers exhibit a highly-specific asymmetric mutation pattern within CTCF motifs attributable to ultraviolet irradiation and differential nucleotide excision repair (NER). CTCF binding site mutations form independent of replication timing and are enriched at sites of CTCF/cohesin complex binding, suggesting a role for cohesin in stabilizing CTCF-DNA binding and impairing NER. Performing CTCF ChIP-seq in a melanoma cell-line, we show CTCF binding site mutations to be functional by demonstrating allele-specific reduction of CTCF binding to mutant alleles. While topologically-associating domains with mutated CTCF anchors in melanoma contain differentially-expressed cancer-associated genes, CTCF motif mutations appear generally under neutral selection. However, the frequency and potential functional impact of such mutations in melanoma highlights the need to consider their impact on cellular phenotype in individual genomes.

2016-12-13 | GSE81945 | GEO

Spec-seq sequencing data for CTCF [2018 series]

Project description:We used Spec-seq method to quantifiy the in-vitro binding specificity of mouse CTCF insulator protein, particularly concerning its upstream motif. Our results confirmed the previously found "upstream motif“ with 5 or 6nt space to the core motif, which is conferred by CTCF's finger 10 and 11.

2018-02-10 | GSE110155 | GEO

A genome-wide map of CTCF multivalency redefines the CTCF code

Project description:The “CTCF code” hypothesis posits that CTCF pleotropic functions are driven by recognition of diverse DNA sequences through combinatorial use of its 11 zinc fingers (ZFs). This model however is supported by in vitro binding studies of a limited number of sequences. To directly test CTCF multivalency in vivo we here define ZF binding requirements at ~50,000 genomic sites in primary lymphocytes. We find that CTCF reads sequence diversity through ZF clustering. ZFs4-7 anchor CTCF to ~80% of targets containing the 20bp core motif. Non-conserved flanking sequences are recognized by ZFs1-2 and ZFs8- 11 clusters, which also stabilize CTCF broadly. Alternatively, CTCF employ ZFs9-11 to associate with a second phylogenetically-conserved upstream motif at ~15% of its sites. Individually, ZFs increase overall binding affinity and chromatin residence time. Unexpectedly, we also uncover a conserved downstream DNA motif that destabilizes CTCF occupancy. CTCF thus associates with a wide array of DNA modules via combinatorial clustering of its 11 ZFs.

2011-11-19 | GSE33819 | GEO

Altered topology drives oncogenic programs in SDH-deficient GIST

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>

| phs001906 | dbGaP

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