A CRISPR-Cas9 screen identifies essential CTCF anchor sites for Estrogen Receptor-driven breast cancer cell proliferation
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PROVIDER: PRJNA513033 | ENA |
REPOSITORIES: ENA
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Project description:Estrogen receptor α (ERα) is an enhancer activating transcription factor, a key driver of breast cancer, and a main target for cancer therapy. ER-mediated gene regulation requires proper chromatin-conformation to facilitate interactions between ER-bound enhancers and their target promoters. A major determinant of chromatin structure is the CCCTC-binding factor (CTCF), that dimerizes and together with cohesin stabilizes chromatin loops and forms the boundaries of topologically associated domains. However, whether CTCF-binding elements (CBEs) are essential for ER-driven cell proliferation is unknown. To address this question in a global manner, we implemented a CRISPR-based functional genetic screening approach targeting CBEs located in the vicinity of ERα-bound enhancers. We identified four functional CBEs and demonstrated the role of one in inducing chromatin conformation changes in favor of activation of PREX1, a key ERα target gene in breast cancer. Indeed, high PREX1 expression is a bona-fide marker of ER-dependency in cell lines, and associated with good outcome after anti-hormonal treatment. Altogether, our data show that distinct CTCF-mediated chromatin structures are required for ER- driven breast cancer cell proliferation.
2020-01-04 | GSE124667 | GEO
Project description:Estrogen receptor α (ERα) is an enhancer activating transcription factor, a key driver of breast cancer and a main target for cancer therapy. ERα-mediated gene regulation requires proper chromatin-conformation to facilitate interactions between ERα-bound enhancers and their target promoters. A major determinant of chromatin structure is the CCCTC-binding factor (CTCF), that dimerizes and together with cohesin stabilizes chromatin loops and forms the boundaries of topologically associated domains. However, whether CTCF-binding elements (CBEs) are essential for ERα-driven cell proliferation is unknown. To address this question in a global manner, we implemented a CRISPR-based functional genetic screen targeting CBEs located in the vicinity of ERα-bound enhancers. We identified four functional CBEs and demonstrated the role of one of them in inducing chromatin conformation changes in favor of activation of PREX1, a key ERα target gene in breast cancer. Indeed, high PREX1 expression is a bona-fide marker of ERα-dependency in cell lines, and is associated with good outcome after anti-hormonal treatment. Altogether, our data show that distinct CTCF-mediated chromatin structures are required for ERα- driven breast cancer cell proliferation.
| S-EPMC6765117 | biostudies-literature
Project description:Chromosome loops shift dynamically during development, homeostasis, and disease. CTCF is known to anchor loops and construct 3D genomes, but how anchor sites are selected is not yet understood. Here we unveil Jpx RNA as a determinant of anchor selectivity. Jpx RNA targets thousands of genomic sites, preferentially binding promoters of active genes. Depleting Jpx RNA causes ectopic CTCF binding, massive shifts in chromosome looping, and downregulation of >700 Jpx target genes. Without Jpx, thousands of lost loops are replaced by de novo loops anchored by ectopic CTCF sites. Although Jpx controls CTCF binding on a genome-wide basis, it acts selectively at the subset of developmentally sensitive CTCF sites. Specifically, Jpx targets low-affinity CTCF motifs and displaces CTCF protein through competitive inhibition. We conclude that Jpx acts as a CTCF release factor and shapes the 3D genome by regulating anchor site usage.
2021-12-01 | GSE144056 | GEO
Project description:CCCTC-binding factor (CTCF) is a conserved zinc finger transcription factor involved in chromatin looping. Recent evidence has shown a role for CTCF in ER biology. This experiment maps CTCF binding genome-wide in breast cancer cells and shows that CTCF binding does not change with estrogen or tamoxifen treatment. We find a small but reproducible proportion of CTCF binding events that overlap with both the nuclear receptor estrogen receptor and the forkhead protein FoxA1. These overlapping binding events are likely to be functional as they are biased towards estrogen-regulated genes. In addition, we identify cell-line specific CTCF binding events. These cell-line specific CTCF binding events are more likely to be associated with cell-line specific ER vinding events and are also more likely to be adjacent to genes that are expressed in that particular cell line. These data suggest a positive, pro-transcriptional role for CTCF in ER-mediated gene expression in breast cancer cells.
2011-12-07 | E-MTAB-740 | biostudies-arrayexpress
Project description:Jpx RNA regulates CTCF anchor site selection and formation of chromosome loops
| PRJNA602661 | ENA
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.
2023-06-17 | PXD043070 | Pride
Project description:In our work we used high-throughput sequencing methods to get insight in the role of CTCF in ER-mediated gene regulation in luminal breast cancer cells. After assessing genome-wide binding of CTCF, ER, FOXA1 and Lamin B in MCF7 cells treated with estrogen for different time points, we could correlate the interaction to the chromatin with estrogen-induced de novo transcription (from GRO-seq data) and loop formation (from ChIA-PET, Fullwood et al., 2009). We observed that CTCF binding correlates with ER-mediated transcription and its depletion can affect ER-ER loop formation and subsequently gene expression.
2016-12-10 | GSE85106 | GEO
Project description:In our work we used high-throughput sequencing methods to get insight in the role of CTCF in ER-mediated gene regulation in luminal breast cancer cells. After assessing genome-wide binding of CTCF, ER, FOXA1 and Lamin B in MCF7 cells treated with estrogen for different time points, we could correlate the interaction to the chromatin with estrogen-induced de novo transcription (from GRO-seq data) and loop formation (from ChIA-PET, Fullwood et al., 2009). We observed that CTCF binding correlates with ER-mediated transcription and its depletion can affect ER-ER loop formation and subsequently gene expression.
2016-12-10 | GSE85088 | GEO
Project description:Precise spatiotemporal regulation of genetic programs, driven by cellspecific super-enhancers, is paramount for the function of cell lineages. Studies have suggested that insulated neighborhoods, formed by the zincfinger protein CTCF, sequester genes and their associated enhancers thus preventing them from trespassing on off-target genes. Although this could explain the enhancer-gene-specificity conundrum, there is limited genetic evidence that the search space of cell-specific super-enhancers is constrained by CTCF. We have addressed this question in the Wap locus with its exceptional mammary-specific super-enhancer, which is separated by five CTCF sites from neighboring genes. Three of these sites are positioned between the Wap super-enhancer and the widely expressed Ramp3. Enhancer deletions demonstrated that the Wap super-enhancer controls Ramp3 expression despite the presence of three parting CTCF sites. Individual and combinatorial deletions of these CTCF sites revealed cell-specific functions of the conserved anchor site. Although unable to block super-enhancer activity, it muffled its impact on Ramp3 in mammary tissue. Unexpectedly, this CTCF site was obligatory for Ramp3 expression in cerebellum, suggesting the coinciding presence of regulatory elements. While our results suggest a surprisingly limited in vivo role for a CTCF anchor in blocking a mammary-specific super-enhancer, they also implicate this site in cerebellum-specific gene activation. Our study illustrates additional complexities of CTCF sites supporting tissue-specific functions.
2017-05-25 | GSE92931 | GEO
Project description:Precise spatiotemporal regulation of genetic programs, driven by cellspecific super-enhancers, is paramount for the function of cell lineages. Studies have suggested that insulated neighborhoods, formed by the zincfinger protein CTCF, sequester genes and their associated enhancers thus preventing them from trespassing on off-target genes. Although this could explain the enhancer-gene-specificity conundrum, there is limited genetic evidence that the search space of cell-specific super-enhancers is constrained by CTCF. We have addressed this question in the Wap locus with its exceptional mammary-specific super-enhancer, which is separated by five CTCF sites from neighboring genes. Three of these sites are positioned between the Wap super-enhancer and the widely expressed Ramp3. Enhancer deletions demonstrated that the Wap super-enhancer controls Ramp3 expression despite the presence of three parting CTCF sites. Individual and combinatorial deletions of these CTCF sites revealed cell-specific functions of the conserved anchor site. Although unable to block super-enhancer activity, it muffled its impact on Ramp3 in mammary tissue. Unexpectedly, this CTCF site was obligatory for Ramp3 expression in cerebellum, suggesting the coinciding presence of regulatory elements. While our results suggest a surprisingly limited in vivo role for a CTCF anchor in blocking a mammary-specific super-enhancer, they also implicate this site in cerebellum-specific gene activation. Our study illustrates additional complexities of CTCF sites supporting tissue-specific functions.
2017-05-25 | GSE97803 | GEO