DNA G-quadruplexes contribute to CTCF and cohesin recruitment
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ABSTRACT:
PROVIDER: PRJNA723750 | ENA |
REPOSITORIES: ENA
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Project description:G-quadruplex (G4) sites in the human genome frequently colocalize with CCCTC-binding factor (CTCF)-bound sites within topologically associating domains (TADs) or at TAD boundaries. We investigated three mechanisms by which G4s may contribute to CTCF recruitment. One involved direct interactions between CTCF and G4s that persisted in the G0/G1 phase of the cell cycle. Synthetic G4s from CpG islands (CGIs) formed complexes with CTCF in vitro, and CTCF occupancy at the respective sites in the genome was modulated by a G4-stabilizing ligand. Another possible mechanism was through G4 interference with DNA methyltransferase activity in CGIs. Bioinformatics analysis confirmed that G4s underlie the association between CTCF and CGIs, but did not support a critical role for methylation in CTCF recruitment to G4-harboring CGIs. The third mechanism was through attracting additional protein factors. We found that G4s are recognized by the nucleosome density modulating high-mobility group (HMG) proteins and the cohesin-interacting protein additional sex combs-like 1. The affinity for these proteins is the basis for indirect G4 contributions to CTCF positioning and TAD demarcation.
2021-04-23 | GSE173074 | GEO
Project description: Not available
| S-EPMC8269367 | biostudies-literature
Project description:Recent studies of genome-wide chromatin interactions have revealed that the human genome is partitioned into many self-associating topological domains. The boundary sequences are enriched for binding sites of CTCF and the cohesin complex, implicating these two factors in the establishment or maintenance of topological domains. To determine the role of cohesin and CTCF in higher order chromatin architecture in human cells, we proteolytically cleaved the cohesin complex from interphase chromatin and examined changes in chromosomal organization as well as transcriptome. We observed a general loss of local chromosomal interactions upon disruption of cohesin complex, but the topological domains remain intact. However, we found that depletion of CTCF by RNA interference in these cells not only reduced intra-domain interactions but also increased inter-domain interactions. Further more, distinct groups of genes become mis-regulated upon depletion of cohesin and CTCF. Taken together, these observations suggest that CTCF and cohesin contribute in different ways to chromatin organization and gene regulation. Hi-C and mRNA-seq experiments in Cohesin and CTCF depleted HEK293 cells
2013-12-16 | E-GEOD-44267 | biostudies-arrayexpress
Project description:Inborn defects in DNA repairare associated with complex developmental disorders whose causal mechanisms are poorly understood. Using an in vivo biotinylation tagging approach in mice, we show that the nucleotide excision repair (NER) structure-specific endonuclease ERCC1-XPF complex interacts with the insulator binding protein CTCF, the cohesin subunits SMC1A and SMC3 and with MBD2; the factors co-localize with ATRX at the promoters and control regions (ICRs) of imprinted genes during postnatal hepatic development. Loss of Ercc1or exposure to mitomycin C triggers the localization of CTCF to heterochromatin, the dissociation of the CTCF-cohesin complex and ATRXfrom promoters and ICRs,altered histone marks and the aberrant developmental expression of imprinted genes without altering DNA methylation. We propose that ERCC1-XPF cooperates with CTCF and the cohesinto facilitatet he developmental silencing of imprinted genes and that persistent DNA damage triggers chromatin changes that affect gene expression programs associated with NER disorders.
2017-04-04 | PXD005897 | Pride
Project description:To understand how chromatin domains coordinate gene expression, we dissected select genetic elements organizing topology and transcription around the Prdm14 super enhancer in mouse embryonic stem cells. Taking advantage of allelic polymorphisms, we developed methods to sensitively analyze changes in chromatin topology, gene expression, and protein recruitment. We show that enhancer insulation does not strictly rely on loop formation between its flanking boundaries, that the enhancer activates the Slco5a1 gene beyond its prominent domain boundary, and that it recruits cohesin for loop extrusion. Upon boundary inversion, we find that oppositely-oriented CTCF terminates extrusion trajectories but does not stall cohesin, while deleted or mutated CTCF sites allow cohesin to extend its trajectory. Enhancer-mediated gene activation occurs independent of paused loop extrusion near the gene promoter. We expand upon the loop extrusion model to propose that cohesin loading and extrusion trajectories originating at an enhancer contribute to gene activation.
2021-06-30 | GSE173354 | GEO
Project description:CCCTC-binding factor (CTCF) is an architectural protein involved in the three-dimensional organization of chromatin. In this study, we systematically assayed the 3D genomic contact profiles of hundreds of CTCF binding sites in multiple tissues with high-resolution 4C-seq. We find both developmentally stable and dynamic chromatin loops. As recently reported, our data also suggest that chromatin loops preferentially form between CTCF binding sites oriented in a convergent manner. To directly test this, we used CRISPR-Cas9 genome editing to delete core CTCF binding sites in three loci, including the CTCF site in the Sox2 super-enhancer. In all instances, CTCF and cohesin recruitment were lost, and chromatin loops with distal CTCF sites were disrupted or destabilized. Re-insertion of oppositely oriented CTCF recognition sequences restored CTCF and cohesin recruitment, but did not re-establish chromatin loops. We conclude that CTCF binding polarity plays a functional role in the formation of higher order chromatin structure. 4C-seq was performed on a large number of viewpoints in E14 embryonic stem cells, neural precursor cells and primary fetal liver cells
2015-10-29 | E-GEOD-72539 | biostudies-arrayexpress
Project description:Recent studies of genome-wide chromatin interactions have revealed that the human genome is partitioned into many self-associating topological domains. The boundary sequences are enriched for binding sites of CTCF and the cohesin complex, implicating these two factors in the establishment or maintenance of topological domains. To determine the role of cohesin and CTCF in higher order chromatin architecture in human cells, we proteolytically cleaved the cohesin complex from interphase chromatin and examined changes in chromosomal organization as well as transcriptome. We observed a general loss of local chromosomal interactions upon disruption of cohesin complex, but the topological domains remain intact. However, we found that depletion of CTCF by RNA interference in these cells not only reduced intra-domain interactions but also increased inter-domain interactions. Further more, distinct groups of genes become mis-regulated upon depletion of cohesin and CTCF. Taken together, these observations suggest that CTCF and cohesin contribute in different ways to chromatin organization and gene regulation.
2013-12-16 | GSE44267 | GEO
Project description:Cohesin catalyses the folding of the genome into loops that are anchored by CTCF. The molecular mechanism of how cohesin and CTCF structure the 3D genome has remained unclear. Here we show that a segment within the CTCF N terminus interacts with the SA2-SCC1 subunits of cohesin. A 2.6 Å crystal structure of SA2-SCC1 in complex with CTCF reveals the molecular basis of the interaction. We demonstrate that this interaction is specifically required for CTCF-anchored loops and contributes to the positioning of cohesin at CTCF-binding sites. A similar motif is present in a number of established and novel cohesin ligands, including the cohesin release factor WAPL. Our data suggest that CTCF enables chromatin loop formation by protecting cohesin against loop release. These results provide fundamental insights into the molecular mechanism that enables dynamic regulation of chromatin folding by cohesin and CTCF.
2020-01-07 | GSE126636 | GEO
Project description:Cohesin catalyses the folding of the genome into loops that are anchored by CTCF. The molecular mechanism of how cohesin and CTCF structure the 3D genome has remained unclear. Here we show that a segment within the CTCF N terminus interacts with the SA2-SCC1 subunits of cohesin. A 2.6 Å crystal structure of SA2-SCC1 in complex with CTCF reveals the molecular basis of the interaction. We demonstrate that this interaction is specifically required for CTCF-anchored loops and contributes to the positioning of cohesin at CTCF-binding sites. A similar motif is present in a number of established and novel cohesin ligands, including the cohesin release factor WAPL. Our data suggest that CTCF enables chromatin loop formation by protecting cohesin against loop release. These results provide fundamental insights into the molecular mechanism that enables dynamic regulation of chromatin folding by cohesin and CTCF.
2020-01-07 | GSE126635 | GEO
Project description:Cohesin catalyses the folding of the genome into loops that are anchored by CTCF. The molecular mechanism of how cohesin and CTCF structure the 3D genome has remained unclear. Here we show that a segment within the CTCF N terminus interacts with the SA2-SCC1 subunits of cohesin. A 2.6 Å crystal structure of SA2-SCC1 in complex with CTCF reveals the molecular basis of the interaction. We demonstrate that this interaction is specifically required for CTCF-anchored loops and contributes to the positioning of cohesin at CTCF-binding sites. A similar motif is present in a number of established and novel cohesin ligands, including the cohesin release factor WAPL. Our data suggest that CTCF enables chromatin loop formation by protecting cohesin against loop release. These results provide fundamental insights into the molecular mechanism that enables dynamic regulation of chromatin folding by cohesin and CTCF.
2020-01-07 | GSE126634 | GEO