Similar Datasets
Project description:Transcription of the cystic fibrosis transmembrane conductance regulator (CFTR) gene is regulated by a set of ubiquitous and cell-type selective cis-regulatory elements (CREs). These elements include extragenic and intronic enhancers that bind cell-type specific transcription factors, as well as architectural protein bound structural elements. We previously reported that loss of the airway-selective -35kb enhancer in 16HBE14o- airway epithelial cells disrupts normal enhancer-promoter looping at the CFTR locus and nearly abolishes its expression. Here we expand on previous work, and explore the effect of relocation of the 500bp -35kb enhancer core to an ectopic site in intron 1 of CFTR on gene expression and chromatin dynamics. We find that although genomic relocation of this element is not able to fully restore CFTR expression to wild-type levels, the -35kb sequence is able establish a de novo enhancer signature at chromatin at the site of insertion. Additionally, the relocated -35kb enhancer is able to form chromatin contacts with known CFTR CREs. These studies reveal important direct chromatin effects, as well as limitations, of CFTR enhancers, and provide important considerations when targeting the CFTR locus for novel therapeutic gene editing.
2022-12-13 | GSE203559 | GEO
Project description:Transcription of the cystic fibrosis transmembrane conductance regulator (CFTR) gene is regulated by a set of ubiquitous and cell-type selective cis-regulatory elements (CREs). These elements include extragenic and intronic enhancers that bind cell-type specific transcription factors, as well as architectural protein bound structural elements. We previously reported that loss of the airway-selective -35kb enhancer in 16HBE14o- airway epithelial cells disrupts normal enhancer-promoter looping at the CFTR locus and nearly abolishes its expression. Here we expand on previous work, and explore the effect of relocation of the 500bp -35kb enhancer core to an ectopic site in intron 1 of CFTR on gene expression and chromatin dynamics. We find that although genomic relocation of this element is not able to fully restore CFTR expression to wild-type levels, the -35kb sequence is able establish a de novo enhancer signature at chromatin at the site of insertion. Additionally, the relocated -35kb enhancer is able to form chromatin contacts with known CFTR CREs. These studies reveal important direct chromatin effects, as well as limitations, of CFTR enhancers, and provide important considerations when targeting the CFTR locus for novel therapeutic gene editing.
2022-12-13 | GSE203558 | GEO
Project description:An ectopic enhancer restores CFTR expression through de novo chromatin looping.
| PRJNA841375 | ENA
Project description:An ectopic enhancer restores CFTR expression through de novo chromatin looping [ATAC-seq]
| PRJNA841377 | ENA
Project description:An ectopic enhancer restores CFTR expression through de novo chromatin looping [4C-seq]
| PRJNA841376 | ENA
Project description:Mammalian genes transcribe RNA not continuously, but in bursts. Transcriptional output can be modulated by altering burst fraction or burst size, but how regulatory elements control bursting parameters remains unclear. Single-molecule RNA FISH experiments revealed that the ?-globin enhancer (LCR) predominantly augments transcriptional burst fraction of the ?-globin gene with modest stimulation of burst size. To specifically measure the impact of long-range chromatin contacts on transcriptional bursting, we forced an LCR-?-globin promoter chromatin loop. We observed that raising contact frequencies increases burst fraction but not burst size. In cells in which two developmentally distinct LCR-regulated globin genes are cotranscribed in cis, burst sizes of both genes are comparable. However, allelic co-transcription of both genes is statistically disfavored, suggesting mutually exclusive LCR-gene contacts. These results are consistent with competition between the ?-type globin genes for LCR contacts and suggest that LCR-promoter loops are formed and released with rapid kinetics.
| S-EPMC4842148 | biostudies-literature
Project description:MLL4 is an essential subunit of the histone H3 Lys4 (H3K4)-methylation complexes. We found that MLL4 deficiency compromised the development of regulatory T cells (Treg cells) and resulted in a substantial decrease in monomethylated H3K4 (H3K4me1) and chromatin interaction at putative gene enhancers, a considerable portion of which were not direct targets of MLL4 but were enhancers that interacted with MLL4-bound sites. The decrease in H3K4me1 and chromatin interaction at the enhancers not bound by MLL4 correlated with MLL4 binding at distant interacting regions. Deletion of an upstream MLL4-binding site diminished the abundance of H3K4me1 at the regulatory elements of the gene encoding the transcription factor Foxp3 that were looped to the MLL4-binding site and compromised both the thymic differentiation and the inducible differentiation of Treg cells. We found that MLL4 catalyzed methylation of H3K4 at distant unbound enhancers via chromatin looping, which identifies a previously unknown mechanism for regulating the T cell enhancer landscape and affecting Treg cell differentiation.
| S-EPMC5836551 | biostudies-literature
Project description:During development, looping of an enhancer to a promoter is frequently observed in conjunction with temporal and tissue-specific transcriptional activation. The chromatin insulator-associated protein Alan Shepard (Shep) promotes Drosophila post-mitotic neuronal remodeling by repressing transcription of master developmental regulators, such as brain tumor (brat), specifically in maturing neurons. Since insulator proteins can promote looping, we hypothesized that Shep antagonizes brat promoter interaction with an as yet unidentified enhancer. Using chromatin conformation capture and reporter assays, we identified two enhancer regions that increase in looping frequency with the brat promoter specifically in pupal brains after Shep depletion. The brat promoters and enhancers function independently of Shep, ruling out direct repression of these elements. Moreover, ATAC-seq in isolated neurons demonstrates that Shep restricts chromatin accessibility of a key brat enhancer as well as other enhancers genome-wide in remodeling pupal but not larval neurons. These enhancers are enriched for chromatin targets of Shep and are located at Shep-inhibited genes, suggesting direct Shep inhibition of enhancer accessibility and gene expression during neuronal remodeling. Our results provide evidence for temporal regulation of chromatin looping and enhancer accessibility during neuronal maturation.
| S-EPMC8568962 | biostudies-literature
Project description:BACKGROUND:Genome-wide association studies (GWASs) have identified single-nucleotide polymorphisms (SNPs) that may be genetic factors underlying Alzheimer's disease (AD). However, how these AD-associated SNPs (AD SNPs) contribute to the pathogenesis of this disease is poorly understood because most of them are located in non-coding regions, such as introns and intergenic regions. Previous studies reported that some disease-associated SNPs affect regulatory elements including enhancers. We hypothesized that non-coding AD SNPs are located in enhancers and affect gene expression levels via chromatin loops. METHODS:To characterize AD SNPs within non-coding regions, we extracted 406?AD SNPs with GWAS p-values of less than 1.00?×?10-?6 from the GWAS catalog database. Of these, we selected 392 SNPs within non-coding regions. Next, we checked whether those non-coding AD SNPs were located in enhancers that typically regulate gene expression levels using publicly available data for enhancers that were predicted in 127 human tissues or cell types. We sought expression quantitative trait locus (eQTL) genes affected by non-coding AD SNPs within enhancers because enhancers are regulatory elements that influence the gene expression levels. To elucidate how the non-coding AD SNPs within enhancers affect the gene expression levels, we identified chromatin-chromatin interactions by Hi-C experiments. RESULTS:We report the following findings: (1) nearly 30% of non-coding AD SNPs are located in enhancers; (2) eQTL genes affected by non-coding AD SNPs within enhancers are associated with amyloid beta clearance, synaptic transmission, and immune responses; (3) 95% of the AD SNPs located in enhancers co-localize with their eQTL genes in topologically associating domains suggesting that regulation may occur through chromatin higher-order structures; (4) rs1476679 spatially contacts the promoters of eQTL genes via CTCF-CTCF interactions; (5) the effect of other AD SNPs such as rs7364180 is likely to be, at least in part, indirect through regulation of transcription factors that in turn regulate AD associated genes. CONCLUSION:Our results suggest that non-coding AD SNPs may affect the function of enhancers thereby influencing the expression levels of surrounding or distant genes via chromatin loops. This result may explain how some non-coding AD SNPs contribute to AD pathogenesis.
| S-EPMC6734281 | biostudies-literature
Project description:Discriminating the gene target of a distal regulatory element from other nearby transcribed genes is a challenging problem with the potential to illuminate the causal underpinnings of complex diseases. We present TargetFinder, a computational method that reconstructs regulatory landscapes from diverse features along the genome. The resulting models accurately predict individual enhancer-promoter interactions across multiple cell lines with a false discovery rate up to 15 times smaller than that obtained using the closest gene. By evaluating the genomic features driving this accuracy, we uncover interactions between structural proteins, transcription factors, epigenetic modifications, and transcription that together distinguish interacting from non-interacting enhancer-promoter pairs. Most of this signature is not proximal to the enhancers and promoters but instead decorates the looping DNA. We conclude that complex but consistent combinations of marks on the one-dimensional genome encode the three-dimensional structure of fine-scale regulatory interactions.
| S-EPMC4910881 | biostudies-literature