Project description:Despite the role of the estrogen receptor alpha (ERalpha) pathway as a key growth driver for breast cells, the phenotypic consequence of exogenous introduction of ERalpha into ERalpha-negative cells paradoxically has been growth inhibition. We map the binding profiles of ERalpha and its interacting transcription factors (TFs), FOXA1 and GATA3, in MCF-7 breast carcinoma cells. We observe that these three TFs form a functional enhanceosome and cooperatively modulate the transcriptional networks previously ascribed to ERalpha alone. We demonstrate that these enhanceosome-occupied sites are associated with optimal enhancer characteristics with highest p300 coactivator recruitment, RNA Pol II occupancy, and chromatin opening. The enhancesome binding sites appear to regulate the genes driving core ERalpha function. Most importantly, we show that transfection of all three TFs was necessary to reprogram the ERalpha-negative MDA-MB-231 and BT-459 cells to restore the estrogen responsive growth and to transcriptionally resemble the estrogen-treated ERalpha-positive MCF-7 cells. Cumulatively, these results suggest that all of the enhanceosome components comprising ERalpha, FOXA1 and GATA3 are necessary for the full repertoire of the cancer-associated effects of the ERalpha. The analysis of ERalpha, FOXA1, and GATA3 in MCF-7 cancer cells was done by ChIP-seq data obtained either with estradiol (E2) stimulation or without stimulation using vehicle as a control. Using the ERalpha bindings defined by ChIP-seq (GSE23893), FOXA1 bindings (GSE26831), and GATA3 bindings (this Series), we analyzed the enhanceosome effect of the overlapped binding sites from ERalpha, FOXA1 and GATA3.
Project description:Despite the role of the estrogen receptor alpha (ERalpha) pathway as a key growth driver for breast cells, the phenotypic consequence of exogenous introduction of ERalpha into ERalpha-negative cells paradoxically has been growth inhibition. We map the binding profiles of ERalpha and its interacting transcription factors (TFs), FOXA1 and GATA3 in MCF-7 breast carcinoma cells. We observe that these three TFs form a functional enhanceosome and cooperatively modulate the transcriptional networks previously ascribed to ERalpha alone. We demonstrate that these enhanceosome occupied sites are associated with optimal enhancer characteristics with highest p300 coactivator recruitment, RNA Pol II occupancy, and chromatin opening. The enhancesome binding sites appear to regulate the genes driving core ERalpha function. Most importantly, we show that the transfection of all three TFs was necessary to reprogramme the ERalpha-negative MDA-MB-231 and BT-459 cells to restore the estrogen responsive growth and to transcriptionally resemble the estrogen treated ERalpha-positive MCF-7 cells. Cumulatively, these results suggest that all the enhanceosome components comprising ERalpha, FOXA1 and GATA3 are necessary for the full repertoire of cancer associated effects of the ERalpha. Illumina HumanRef-8 v3 Expression BeadChip was used to measure the gene expression levels from ERalpha negative breast cancer cell MDA-MB-231 with different transfections: with vector control, with ERalpha only, or with ERalpha+FOXA1+GATA3 combined.
Project description:Despite the role of the estrogen receptor alpha (ERalpha) pathway as a key growth driver for breast cells, the phenotypic consequence of exogenous introduction of ERalpha into ERalpha-negative cells paradoxically has been growth inhibition. We map the binding profiles of ERalpha and its interacting transcription factors (TFs), FOXA1 and GATA3 in MCF-7 breast carcinoma cells. We observe that these three TFs form a functional enhanceosome and cooperatively modulate the transcriptional networks previously ascribed to ERalpha alone. We demonstrate that these enhanceosome occupied sites are associated with optimal enhancer characteristics with highest p300 coactivator recruitment, RNA Pol II occupancy, and chromatin opening. The enhancesome binding sites appear to regulate the genes driving core ERalpha function. Most importantly, we show that the transfection of all three TFs was necessary to reprogramme the ERalpha-negative MDA-MB-231 and BT-459 cells to restore the estrogen responsive growth and to transcriptionally resemble the estrogen treated ERalpha-positive MCF-7 cells. Cumulatively, these results suggest that all the enhanceosome components comprising ERalpha, FOXA1 and GATA3 are necessary for the full repertoire of cancer associated effects of the ERalpha.
Project description:Despite the role of the estrogen receptor alpha (ERalpha) pathway as a key growth driver for breast cells, the phenotypic consequence of exogenous introduction of ERalpha into ERalpha-negative cells paradoxically has been growth inhibition. We map the binding profiles of ERalpha and its interacting transcription factors (TFs), FOXA1 and GATA3, in MCF-7 breast carcinoma cells. We observe that these three TFs form a functional enhanceosome and cooperatively modulate the transcriptional networks previously ascribed to ERalpha alone. We demonstrate that these enhanceosome-occupied sites are associated with optimal enhancer characteristics with highest p300 coactivator recruitment, RNA Pol II occupancy, and chromatin opening. The enhancesome binding sites appear to regulate the genes driving core ERalpha function. Most importantly, we show that transfection of all three TFs was necessary to reprogram the ERalpha-negative MDA-MB-231 and BT-459 cells to restore the estrogen responsive growth and to transcriptionally resemble the estrogen-treated ERalpha-positive MCF-7 cells. Cumulatively, these results suggest that all of the enhanceosome components comprising ERalpha, FOXA1 and GATA3 are necessary for the full repertoire of the cancer-associated effects of the ERalpha.
Project description:Estrogen Receptor (ER) is a steroid hormone receptor that regulates epithelial genes in breast cancer. ER forms a regulatory network with the other transcription factors, FOXA1 and GATA3. GATA3 is known to be capable of specifying chromatin localization of FOXA1 and ER. GATA3 has been identified as one of the most frequently mutated genes in breast cancer. However, how GATA3 mutations impact this transcriptional network is unknown. Here we investigate the function of one of the recurrent patient-derived GATA3 mutations (R330fs) for this regulatory network. Genomic analysis indicates that the R330fs mutant can disrupt the cooperative action of ER, FOXA1, and GATA3, and induce chromatin relocalization of these factors. Relocalizations of ER and FOXA1 are associated with altered chromatin architectures leading to differential gene expression in the GATA3 mutant cells. These results suggest the active role of GATA3 mutants in ER positive breast tumors.
Project description:Using the estrogen receptor alpha (ERalpha) as a model ligand inducible transcription factor, we sought to explicitly define parameters that determine transcription factor binding site selection on a genomic scale in an inducible system that minimizes confounding chromatin effects by the transcription factor itself. By examining several genetic and epigenetic parameters, we find that an energetically favorable estrogen response element (ERE) motif sequence, evidence of occupancy of a "pioneering" transcription factor FOXA1, the presence of the enhancer mark, H3K4me1, and an open chromatin configuration (FAIRE) at the pre-ligand state provide specificity for ER binding. Genome-wide ChIP-sequencing was done in MCF-7 cancer cell line for the following histone H3 modifications: monomethylation H3K4me1, trimethylation H3K4me3, H3K9me3, H3K27me3, acetylation H3K9ac, H3K14ac. In addition sequencing of RNA Pol II was done at same treatment conditions (E2 and DMSO). In addition, we assessed the chromatin configuration of ERα binding sites by deeply sequencing fragments isolated by Formaldehyde-Assisted Isolation of Regulatory Elements (FAIRE) (Giresi et al, 2007) which enriches for nucleosome free genomic DNA in the aqueous phase of a phenol extraction.
Project description:Using the estrogen receptor alpha (ERalpha) as a model ligand inducible transcription factor, we sought to explicitly define parameters that determine transcription factor binding site selection on a genomic scale in an inducible system that minimizes confounding chromatin effects by the transcription factor itself. By examining several genetic and epigenetic parameters, we find that an energetically favorable estrogen response element (ERE) motif sequence, evidence of occupancy of a "pioneering" transcription factor FOXA1, the presence of the enhancer mark, H3K4me1, and an open chromatin configuration (FAIRE) at the pre-ligand state provide specificity for ER binding. Genome-wide ChIP-sequencing was done in MCF-7 cancer cell line for the following histone H3 modifications: monomethylation H3K4me1, trimethylation H3K4me3, H3K9me3, H3K27me3, acetylation H3K9ac, H3K14ac. In addition sequencing of RNA Pol II was done at same treatment conditions (E2 and DMSO). In addition, we assessed the chromatin configuration of ERα binding sites by deeply sequencing fragments isolated by Formaldehyde-Assisted Isolation of Regulatory Elements (FAIRE) (Giresi et al, 2007) which enriches for nucleosome free genomic DNA in the aqueous phase of a phenol extraction.
Project description:The transcription factor GATA3 is a favorable prognostic indicator in estrogen receptor-M-NM-1 (ERM-NM-1)-positive breast tumors in which it participates with ERa and FOXA1 in a complex transcriptional regulatory program driving tumor growth. Paradoxically, GATA3 mutations are frequent in breast cancer and have been classified as drivers. To elucidate the contribution(s) of GATA3 alterations to oncogenesis, we studied two breast cancer cell lines, MCF7, which carries a heterozygous frameshift mutation in the second zinc finger of GATA3, and T47D, wild-type at this locus. Heterozygosity for the truncating mutation conferred protection from regulated turnover of GATA3, ERa and FOXA1 following estrogen stimulation. Thus, mutant GATA3 uncouples protein-level regulation of master regulatory transcription factors from hormone action. Consistent with increased protein stability, ChIP-seq profiling identified stronger accumulation of GATA3 in cells bearing the mutation, albeit with a similar distribution across the genome. We propose that this specific, cancer-derived mutation in GATA3 deregulates physiologic protein turnover, stabilizes GATA3 binding across the genome and modulates the response of mammary epithelial cells to hormone signaling, thus conferring a selective growth advantage. Genome-wide mapping of GATA3 in two cell lines. There were two biological replicates and unchipped (input) DNA was used as reference.
Project description:Pioneer transcription factors bind to silent chromatin, and initiate cell fate conversion. One potential pioneer factor, GATA3, is a critical component for multiple cellular programs. GATA3 is of particular interest as it regulates gene expression in breast cancers, and low expression correlates with poor prognosis. Here we demonstrate the pioneering activity of GATA3 utilizing a cellular reprogramming system (the mesenchymal-epithelial transition) in breast cancer cells. During the epithelial transition, GATA3 catalyzes chromatin reprogramming by inducing chromatin opening, active enhancer modifications, and nucleosome remodelling. We determined that the transactivation domain is required for this chromatin reprogramming. Importantly, a mutant lacking the transactivation domain possessed the chromatin binding ability but failed to create open chromatin, suggesting binding alone is not sufficient to induce open chromatin. These data illustrate a fundamental mechanism of GATA3-mediated gene regulation, and provide evidence for a pre-engagement state of closed chromatin bound by a pioneer factor.