Project description:We have integrated and analyzed a large number of data sets from a variety of genomic assays using a novel computational pipeline to provide a global view of estrogen receptor 1 (ESR1; a.k.a. ER?) enhancers in MCF-7 human breast cancer cells. Using this approach, we have defined a class of primary transcripts (eRNAs) that are transcribed uni- or bidirectionally from estrogen receptor binding sites (ERBSs) with an average transcription unit length of ?3-5 kb. The majority are up-regulated by short treatments with estradiol (i.e., 10, 25, or 40 min) with kinetics that precede or match the induction of the target genes. The production of eRNAs at ERBSs is strongly correlated with the enrichment of a number of genomic features that are associated with enhancers (e.g., H3K4me1, H3K27ac, EP300/CREBBP, RNA polymerase II, open chromatin architecture), as well as enhancer looping to target gene promoters. In the absence of eRNA production, strong enrichment of these features is not observed, even though ESR1 binding is evident. We find that flavopiridol, a CDK9 inhibitor that blocks transcription elongation, inhibits eRNA production but does not affect other molecular indicators of enhancer activity, suggesting that eRNA production occurs after the assembly of active enhancers. Finally, we show that an enhancer transcription "signature" based on GRO-seq data can be used for de novo enhancer prediction across cell types. Together, our studies shed new light on the activity of ESR1 at its enhancer sites and provide new insights about enhancer function.
Project description:In this study, we used Global Run-On sequencing (GRO-seq), a method that assays the genome-wide location and orientation of all active RNA polymerases. We generated a global profile of active transcription at ERα binding sites in MCF-7 human breast cancer cells in response to short time course of E2 treatment. This method enabled us to detect active transcription at enhancers and define a class of primary transcripts transcribed uni- or bidirectionally from the ERα binding sites. The raw data used in this study is from GSE27463 but sequenced to a greater depth. Using GRO-seq over a time course (0, 10, 40 min) of estrogen signaling in ER-alpha positive MCF-7 human breast cancer cells.
Project description:In this study, we used Global Run-On sequencing (GRO-seq), a method that assays the genome-wide location and orientation of all active RNA polymerases. We generated a global profile of active transcription at ERM-NM-1 binding sites in MCF-7 human breast cancer cells in response to short time course of E2 treatment. This method enabled us to detect active transcription at enhancers and define a class of primary transcripts transcribed uni- or bidirectionally from the ERM-NM-1 binding sites. The raw data used in this study is from GSE27463 but sequenced to a greater depth. Using GRO-seq over a time course (0, 10, 40 min) of estrogen signaling in ER-alpha positive MCF-7 human breast cancer cells.
Project description:In this study, we used Global Run-On sequencing (GRO-seq), a method that assays the genome-wide location and orientation of all active RNA polymerases. We generated a global profile of active transcription at ERα binding sites in MCF-7 human breast cancer cells in response to short time course of E2 treatment. This method enabled us to detect active transcription at enhancers and define a class of primary transcripts transcribed uni- or bidirectionally from the ERα binding sites. The raw data used in this study is from GSE27463 but sequenced to a greater depth.
Project description:The interplay between mitogenic and proinflammatory signaling pathways play key roles in determining the phenotypes and clinical outcomes of breast cancers. We have used global nuclear run-on coupled with deep sequencing to characterize the immediate transcriptional responses of MCF-7 breast cancer cells treated with estradiol, TNFα, or both. In addition, we have integrated these data with chromatin immunoprecipitation coupled with deep sequencing for estrogen receptor alpha (ERα), the pioneer factor FoxA1 and the p65 subunit of the NF-κB transcription factor. Our results indicate extensive transcriptional interplay between these two signaling pathways, which is observed for a number of classical mitogenic and proinflammatory protein-coding genes. In addition, GRO-seq has allowed us to capture the transcriptional crosstalk at the genomic locations encoding for long non-coding RNAs, a poorly characterized class of RNAs which have been shown to play important roles in cancer outcomes. The synergistic and antagonistic interplay between estrogen and TNFα signaling at the gene level is also evident in the patterns of ERα and NF-κB binding, which relocalize to new binding sites that are not occupied by either treatment alone. Interestingly, the chromatin accessibility of classical ERα binding sites is predetermined prior to estrogen treatment, whereas ERα binding sites gained upon co-treatment with TNFα require NF-κB and FoxA1 to promote chromatin accessibility de novo. Our data suggest that TNFα signaling recruits FoxA1 and NF-κB to latent ERα enhancer locations and directly impact ERα enhancer accessibility. Binding of ERα to latent enhancers upon co-treatment, results in increased enhancer transcription, target gene expression and altered cellular response. This provides a mechanistic framework for understanding the molecular basis for integration of mitogenic and proinflammatory signaling in breast cancer. Using GRO-seq and ChIP-seq (ER, FoxA1 and p65) to assay the molecular crosstalk of MCF-7 cells treated with E2, TNFα or both E2+TNFα.
Project description:The interplay between mitogenic and proinflammatory signaling pathways play key roles in determining the phenotypes and clinical outcomes of breast cancers. We have used global nuclear run-on coupled with deep sequencing to characterize the immediate transcriptional responses of MCF-7 breast cancer cells treated with estradiol, TNFα, or both. In addition, we have integrated these data with chromatin immunoprecipitation coupled with deep sequencing for estrogen receptor alpha (ERα), the pioneer factor FoxA1 and the p65 subunit of the NF-κB transcription factor. Our results indicate extensive transcriptional interplay between these two signaling pathways, which is observed for a number of classical mitogenic and proinflammatory protein-coding genes. In addition, GRO-seq has allowed us to capture the transcriptional crosstalk at the genomic locations encoding for long non-coding RNAs, a poorly characterized class of RNAs which have been shown to play important roles in cancer outcomes. The synergistic and antagonistic interplay between estrogen and TNFα signaling at the gene level is also evident in the patterns of ERα and NF-κB binding, which relocalize to new binding sites that are not occupied by either treatment alone. Interestingly, the chromatin accessibility of classical ERα binding sites is predetermined prior to estrogen treatment, whereas ERα binding sites gained upon co-treatment with TNFα require NF-κB and FoxA1 to promote chromatin accessibility de novo. Our data suggest that TNFα signaling recruits FoxA1 and NF-κB to latent ERα enhancer locations and directly impact ERα enhancer accessibility. Binding of ERα to latent enhancers upon co-treatment, results in increased enhancer transcription, target gene expression and altered cellular response. This provides a mechanistic framework for understanding the molecular basis for integration of mitogenic and proinflammatory signaling in breast cancer.
Project description:Using a chromatin immunoprecipitation-paired end diTag cloning and sequencing strategy, we mapped estrogen receptor alpha (ERalpha) binding sites in MCF-7 breast cancer cells. We identified 1,234 high confidence binding clusters of which 94% are projected to be bona fide ERalpha binding regions. Only 5% of the mapped estrogen receptor binding sites are located within 5 kb upstream of the transcriptional start sites of adjacent genes, regions containing the proximal promoters, whereas vast majority of the sites are mapped to intronic or distal locations (>5 kb from 5' and 3' ends of adjacent transcript), suggesting transcriptional regulatory mechanisms over significant physical distances. Of all the identified sites, 71% harbored putative full estrogen response elements (EREs), 25% bore ERE half sites, and only 4% had no recognizable ERE sequences. Genes in the vicinity of ERalpha binding sites were enriched for regulation by estradiol in MCF-7 cells, and their expression profiles in patient samples segregate ERalpha-positive from ERalpha-negative breast tumors. The expression dynamics of the genes adjacent to ERalpha binding sites suggest a direct induction of gene expression through binding to ERE-like sequences, whereas transcriptional repression by ERalpha appears to be through indirect mechanisms. Our analysis also indicates a number of candidate transcription factor binding sites adjacent to occupied EREs at frequencies much greater than by chance, including the previously reported FOXA1 sites, and demonstrate the potential involvement of one such putative adjacent factor, Sp1, in the global regulation of ERalpha target genes. Unexpectedly, we found that only 22%-24% of the bona fide human ERalpha binding sites were overlapping conserved regions in whole genome vertebrate alignments, which suggest limited conservation of functional binding sites. Taken together, this genome-scale analysis suggests complex but definable rules governing ERalpha binding and gene regulation.
Project description:The interplay between mitogenic and proinflammatory signaling pathways play key roles in determining the phenotypes and clinical outcomes of breast cancers. We have used global nuclear run-on coupled with deep sequencing to characterize the immediate transcriptional responses of MCF-7 breast cancer cells treated with estradiol, TNFM-NM-1, or both. In addition, we have integrated these data with chromatin immunoprecipitation coupled with deep sequencing for estrogen receptor alpha (ERM-NM-1), the pioneer factor FoxA1 and the p65 subunit of the NF-M-NM-:B transcription factor. Our results indicate extensive transcriptional interplay between these two signaling pathways, which is observed for a number of classical mitogenic and proinflammatory protein-coding genes. In addition, GRO-seq has allowed us to capture the transcriptional crosstalk at the genomic locations encoding for long non-coding RNAs, a poorly characterized class of RNAs which have been shown to play important roles in cancer outcomes. The synergistic and antagonistic interplay between estrogen and TNFM-NM-1 signaling at the gene level is also evident in the patterns of ERM-NM-1 and NF-M-NM-:B binding, which relocalize to new binding sites that are not occupied by either treatment alone. Interestingly, the chromatin accessibility of classical ERM-NM-1 binding sites is predetermined prior to estrogen treatment, whereas ERM-NM-1 binding sites gained upon co-treatment with TNFM-NM-1 require NF-M-NM-:B and FoxA1 to promote chromatin accessibility de novo. Our data suggest that TNFM-NM-1 signaling recruits FoxA1 and NF-M-NM-:B to latent ERM-NM-1 enhancer locations and directly impact ERM-NM-1 enhancer accessibility. Binding of ERM-NM-1 to latent enhancers upon co-treatment, results in increased enhancer transcription, target gene expression and altered cellular response. This provides a mechanistic framework for understanding the molecular basis for integration of mitogenic and proinflammatory signaling in breast cancer. Using GRO-seq and ChIP-seq (ER, FoxA1 and p65) to assay the molecular crosstalk of MCF-7 cells treated with E2, TNFM-NM-1 or both E2+TNFM-NM-1.
Project description:BruUV-seq utilizes UV light to introduce transcription-blocking DNA lesions randomly in the genome prior to bromouridine-labeling and deep sequencing of nascent RNA. By inhibiting transcription elongation, but not initiation, pre-treatment with UV light leads to a redistribution of transcription reads resulting in the enhancement of nascent RNA signal towards the 5'-end of genes promoting the identification of transcription start sites (TSSs). Furthermore, transcripts associated with arrested RNA polymerases are protected from 3'-5' degradation and thus, unstable transcripts such as putative enhancer RNA (eRNA) are dramatically increased. Validation of BruUV-seq against GRO-cap that identifies capped run-on transcripts showed that most BruUV-seq peaks overlapped with GRO-cap signal over both TSSs and enhancer elements. Finally, BruUV-seq identified putative enhancer elements induced by tumor necrosis factor (TNF) treatment concomitant with expression of nearby TNF-induced genes. Taken together, BruUV-seq is a powerful new approach for identifying TSSs and active enhancer elements genome-wide in intact cells.