Single base-pair resolution analysis of DNA binding motif with MoMotif reveals an oncogenic function of CTCF zinc-finger 1 mutation.
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE190118 | GEO | 2022/06/28
REPOSITORIES: GEO
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Project description:CCCTC-binding factor (CTCF) plays fundamental roles in transcriptional regulation and chromatin architecture maintenance. CTCF is also a tumour suppressor frequently mutated in cancer, however, the structural and functional impact of mutations have not been examined. We performed molecular and structural characterisation of five cancer-specific CTCF missense zinc finger (ZF) mutations occurring within key intra- and inter-ZF residues. Functional characterisation of CTCF ZF mutations revealed a complete (L309P, R339W, R377H) or intermediate (R339Q) abrogation as well as an enhancement (G420D) of the anti-proliferative effects of CTCF. DNA binding at select sites was disrupted and transcriptional regulatory activities abrogated. Molecular docking and molecular dynamics confirmed that mutations in residues specifically contacting DNA bases or backbone exhibited loss of DNA binding. However, R339Q and G420D were stabilised by the formation of new primary DNA bonds, contributing to gain-of-function. Our data confirm that a spectrum of loss-, change- and gain-of-function impacts on CTCF zinc fingers are observed in cell growth regulation and gene regulatory activities. Hence, diverse cellular phenotypes of mutant CTCF are clearly explained by examining structure-function relationships.
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Project description:Single base-pair resolution analysis of DNA binding motif with MoMotif reveals an oncogenic function of CTCF zinc-finger 1 mutation.
| PRJNA785883 | ENA
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 | GSE190114 | GEO
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
Project description:We have combined standard micrococcal (MNase) digestion of nuclei with a modified protocol for construction paired-end DNA sequencing libraries to map both nucleosomes and subnucleosome-sized particles at single base-pair resolution throughout the budding yeast genome. We found that partially unwrapped nucleosomes and subnucleosome-sized particles can occupy the same position within a cell population, suggesting dynamic behavior. By varying the time of MNase digestion, we have been able to observe changes that reflect differential sensitivity of particles, including eviction of nucleosomes. Our protocol and mapping method provide a general strategy for characterizing full epigenomes. We used micrococcal nuclease mapping, chromatin immunoprecipitation and paired-end sequencing to determine the structure of yeast centromeres at single base-pair resolution.
2011-10-26 | E-GEOD-30551 | biostudies-arrayexpress
Project description:We have combined standard micrococcal nuclease (MNase) digestion of nuclei with a modified protocol for constructing paired-end DNA sequencing libraries to map both nucleosomes and subnucleosome-sized particles at single base-pair resolution throughout the budding yeast genome. We found that partially unwrapped nucleosomes and subnucleosome-sized particles can occupy the same position within a cell population, suggesting dynamic behavior. By varying the time of MNase digestion, we have been able to observe changes that reflect differential sensitivity of particles, including the eviction of nucleosomes. To characterize DNA-binding features of transcription factors, we plotted the length of each fragment versus its position in the genome, which defined the minimal protected region of each factor. This process led to the precise mapping of protected and exposed regions at and around binding sites, and also determination of the degree to which they are flanked by phased nucleosomes and subnucleosome-sized particles. Our protocol and mapping method provide a general strategy for epigenome characterization, including nucleosome phasing and dynamics, ATP-dependent nucleosome remodelers, and transcription factors, from a single-sequenced sample.
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Project description:The transcription factor Egr-1 specifically binds as a monomer to its 9 bp target DNA sequence, GCGTGGGCG, via three zinc fingers and plays important roles in the brain and cardiovascular systems. Using fluorescence-based competitive binding assays, we systematically analyzed the impacts of all possible single-nucleotide substitutions in the target DNA sequence and determined the change in binding free energy for each. Then, we measured the changes in binding free energy for sequences with multiple substitutions and compared them with the sum of the changes in binding free energy for each constituent single substitution. For the DNA variants with two or three nucleotide substitutions in the target sequence, we found excellent agreement between the measured and predicted changes in binding free energy. Interestingly, however, we found that this thermodynamic additivity broke down with a larger number of substitutions. For DNA sequences with four or more substitutions, the measured changes in binding free energy were significantly larger than predicted. On the basis of these results, we analyzed the occurrences of high-affinity sequences in the genome and found that the genome contains millions of such sequences that might functionally sequester Egr-1.
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Project description:Angiogenesis is meticulously controlled by a fine balance between positive and negative regulatory activities. Vascular endothelial growth factor (VEGF) is a predominant angiogenic factor and its dosage is precisely regulated during normal vascular formation. In cancer, VEGF is commonly overproduced, resulting in abnormal neovascularization. VEGF is induced in response to various stimuli including hypoxia; however, very little is known about the mechanisms that confine its induction to ensure proper angiogenesis. Chromatin insulation is a key transcription mechanism that prevents promiscuous gene activation by interfering with the action of enhancers. Here we show that the chromatin insulator-binding factor CTCF binds to the proximal promoter of VEGF. Consistent with the enhancer-blocking mode of chromatin insulators, CTCF has little effect on basal expression of VEGF but specifically affects its activation by enhancers. CTCF knockdown cells are sensitized for induction of VEGF and exhibit elevated proangiogenic potential. Cancer-derived CTCF missense mutants are mostly defective in blocking enhancers at the VEGF locus. Moreover, during mouse retinal development, depletion of CTCF causes excess angiogenesis. Therefore, CTCF-mediated chromatin insulation acts as a crucial safeguard against hyperactivation of angiogenesis.
| S-EPMC3174592 | biostudies-literature
Project description:We have combined standard micrococcal (MNase) digestion of nuclei with a modified protocol for construction paired-end DNA sequencing libraries to map both nucleosomes and subnucleosome-sized particles at single base-pair resolution throughout the budding yeast genome. We found that partially unwrapped nucleosomes and subnucleosome-sized particles can occupy the same position within a cell population, suggesting dynamic behavior. By varying the time of MNase digestion, we have been able to observe changes that reflect differential sensitivity of particles, including eviction of nucleosomes. Our protocol and mapping method provide a general strategy for characterizing full epigenomes.
2011-10-27 | GSE30551 | GEO
Project description:By using a novel chromatin conformation capture (3C) method (Micro Capture-C (MCC)), which allows physical contacts to be determined at base-pair resolution. We demonstrate interactions between different classes of regulatory elements in unprecedented detail. T119_S12-S17 and E14_S10-S14 contains data of viewpoint from enhancers that are active in both ES and erythroid cells. NIPBL, CTCF and Rad21 CHIP libraries were prepared and analyzed as previously reported in Hanssen LLP. et al., 2017.
2021-04-16 | GSE144336 | GEO