Background: The ZNF217 gene, encoding a C2H2 zinc finger protein, is located at 20q13 and found amplified and overexpressed in greater than 20% of breast tumors. Current studies indicate ZNF217 drives tumorigenesis, yet the regulatory mechanisms of ZNF217 are largely unknown. Because ZNF217 associates with chromatin modifying enzymes, we postulate that ZNF217 functions to regulate specific gene signaling networks. Here, we present a large-scale functional genomic analysis of ZNF217, which provides insights into the regulatory role of ZNF217 in MCF7 breast cancer cells. Results: ChIP-seq analysis reveals that the majority of ZNF217 binding sites are located at distal regulatory regions associated with the chromatin marks H3K27ac and H3K4me1. Analysis of ChIPseq transcription factor binding sites shows clustering of ZNF217 with FOXA1, GATA3 and ERalpha binding sites, supported by the enrichment of corresponding motifs for the ERalpha-associated cisregulatory sequences. ERalpha expression highly correlates with ZNF217 in lysates from breast tumors (n=15), and ERalpha co-precipitates ZNF217 and its binding partner CtBP2 from nuclear extracts. Transcriptome profiling following ZNF217 depletion identifies differentially expressed genes co-bound by ZNF217 and ERalpha; gene ontology suggests a role for ZNF217-ERalpha in expression programs associated with ER+ breast cancer studies found in the Molecular Signature Database. Data-mining of expression data from breast cancer patients correlates ZNF217 with reduced overall survival in multiple subtypes. Conclusions: Our genome-wide ZNF217 data suggests a functional role for ZNF217 at ERalpha target genes. Future studies will investigate whether ZNF217 expression contributes to aberrant ERalpha regulatory events in ER+ breast cancer and hormone resistance Overall design: Differential RNA-seq profiling from triplicate biological replicates of MCF7 cells treated with scrambled siRNA or siZNF217.
Global analysis of ZNF217 chromatin occupancy in the breast cancer cell genome reveals an association with ERalpha.
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View SamplesThe TCF7L2 transcription factor is linked to a variety of human diseases, including type 2 diabetes and cancer. One mechanism by which TCF7L2 could influence expression of genes involved in diverse diseases is by binding to distinct regulatory regions in different tissues. To test this hypothesis, we performed ChIP-seq for TCF7L2 in 6 human cell lines. We identified 116,000 non-redundant TCF7L2 binding sites, with only 1,864 sites common to the 6 cell lines. Using ChIP-seq, we showed that many genomic regions that are marked by both H3K4me1 and H3K27Ac are also bound by TCF7L2, suggesting that TCF7L2 plays a critical role in enhancer activity. Bioinformatic analysis of the cell type-specific TCF7L2 binding sites revealed enrichment for multiple transcription factors, including HNF4alpha and FOXA2 motifs in HepG2 cells and the GATA3 motif in MCF7 cells. ChIP-seq analysis revealed that TCF7L2 co-localizes with HNF4alpha and FOXA2 in HepG2 cells and with GATA3 in MCF7 cells. Interestingly, in MCF7 cells the TCF7L2 motif is enriched in most TCF7L2 sites but is not enriched in the sites bound by both GATA3 and TCF7L2. This analysis suggested that GATA3 might tether TCF7L2 to the genome at these sites. To test this hypothesis, we depleted GATA3 in MCF7 cells and showed that TCF7L2 binding was lost at a subset of sites. RNA-seq analysis suggested that TCF7L2 represses transcription when tethered to the genome via GATA3. Our studies demonstrate a novel relationship between GATA3 and TCF7L2, and reveal important insights into TCF7L2-mediated gene regulation. Overall design: RNAseq analysis of MCF7 cells transfected with siCONTROL, siTCF7L2 or siGATA3. ChIP-seq analysis of H3K27ac, H3K4me1, H3K27me3, H3K9me3 in MCF7 cells; H3K4me1 and H3K27ac in HCT116 cells.
Cell type-specific binding patterns reveal that TCF7L2 can be tethered to the genome by association with GATA3.
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View SamplesWe have compared the genome-wide effects on the transcriptome after treatment with ICG-001 (the specific CBP inhibitor) versus C646, a compound that competes with acetyl-coA for the Lys-coA binding pocket of both CBP and p300. We found that both drugs cause large-scale changes in the transcriptome of HCT116 colon cancer cells and PANC1 pancreatic cancer cells, and reverse some tumor-specific changes in gene expression. Interestingly, although the epigenetic inhibitors affect cell cycle pathways in both the colon and pancreatic cancer cell lines, the WNT signaling pathway was affected only in the colon cancer cells. Notably, WNT target genes were similarly down-regulated after treatment of HCT116 with C646 as with ICG-001. Overall design: To identify genes affected by direct targeting of a component of the transcriptional complex implicated in WNT regulation, we used siRNAs to knockdown TCF7L2 in PANC1 cells. Cells were treated with control siRNAs or siRNAs specific for TCF7L2 and RNA was analyzed by RNA-seq.
Three-dimensional analysis reveals altered chromatin interaction by enhancer inhibitors harbors TCF7L2-regulated cancer gene signature.
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View SamplesThe C2H2 zinc finger is the most prevalent DNA-binding motif in the mammalian proteome, with DNA-binding domains usually containing more tandem fingers than are needed for stable sequence-specific DNA recognition. To examine the reason for the frequent presence of multiple zinc fingers, we generated mice lacking finger 1 or finger 4 of the 4-finger DNA-binding domain of Ikaros, a critical regulator of lymphopoiesis and leukemogenesis. Each mutant strain exhibited a specific subset of the phenotypes observed with Ikaros null mice. Of particular relevance, fingers 1 and 4 contributed to distinct stages of B- and T-cell development and finger 4 was selectively required for tumor suppression in thymocytes and in a new model of BCR-ABL+ acute lymphoblastic leukemia. These results, combined with transcriptome profiling (this GEO submission: RNA-Seg of whole thymus from wt and the two ZnF mutants), reveal that different subsets of fingers within multi-finger transcription factors can regulate distinct target genes and biological functions, and they demonstrate that selective mutagenesis can facilitate efforts to elucidate the functions and mechanisms of action of this prevalent class of factors. Overall design: Ikaros RNA-Seq from double positive thymocytes comparing wt (n=2), Ikaros-ZnF1-/- mutant (n=2) and Ikaros-ZnF4-/- mutant (n=2)
Selective regulation of lymphopoiesis and leukemogenesis by individual zinc fingers of Ikaros.
Sex, Age, Specimen part, Cell line, Subject
View SamplesThe C2H2 zinc finger is the most prevalent DNA-binding motif in the mammalian proteome, with DNA-binding domains usually containing more tandem fingers than are needed for stable sequence-specific DNA recognition. To examine the reason for the frequent presence of multiple zinc fingers, we generated mice lacking finger 1 or finger 4 of the 4-finger DNA-binding domain of Ikaros, a critical regulator of lymphopoiesis and leukemogenesis. Each mutant strain exhibited a specific subset of the phenotypes observed with Ikaros null mice. Of particular relevance, fingers 1 and 4 contributed to distinct stages of B- and T-cell development and finger 4 was selectively required for tumor suppression in thymocytes and in a new model of BCR-ABL+ acute lymphoblastic leukemia. These results, combined with transcriptome profiling (this GEO submission: RNA-Seg of whole thymus from wt and the two ZnF mutants), reveal that different subsets of fingers within multi-finger transcription factors can regulate distinct target genes and biological functions, and they demonstrate that selective mutagenesis can facilitate efforts to elucidate the functions and mechanisms of action of this prevalent class of factors. Overall design: RNA-Seq from sorted primary proB cell Hardy Fractions B and C+C'', comparing wt, Ikaros-ZnF1-/- mutant and Ikaros-ZnF4-/- mutant.
Selective regulation of lymphopoiesis and leukemogenesis by individual zinc fingers of Ikaros.
Specimen part, Cell line, Subject
View SamplesPrimary human foreskin fibroblasts (HFF) were exposed to either salt stress (80mM KCl) or heat stress (44ºC). Newly transcribed RNA was labelled by adding 500µM 4-thiouridine (4sU) to the cell culture media for 1h. Total cellular RNA was isolated using Trizol. Newly transcribed RNA was purified following the protocol described in Raedle et al. JoVE 2013. Overall design: Newly transcribed RNA was labelled in one hour intervals during either salt or heat stress (prior to stress, 0-1h or 1-2h). All 4sU-RNA samples were sent for sequencing. Two independent biological replicates were analysed.
HSV-1-induced disruption of transcription termination resembles a cellular stress response but selectively increases chromatin accessibility downstream of genes.
Specimen part, Subject, Time
View SamplesQuiescent stem cells of glioblastoma (GBM), a malignant primary brain tumor, are potential sources for recurrence after therapy. However, the gene expression program underlying the physiology of GBM stem cells remains unclear. We have isolated quiescent GBM cells by engineering them with a knock-in H2B-GFP proliferation reporter and expanding them in a 3D tumor organoid model that mimics tumor heterogeneity. H2B-GFP label retaining quiescent cells were subjected to stem cell assays and RNA-Seq gene expression analysis. While quiescent GBM cells were similar in clonal culture assays to their proliferative counterparts, they displayed higher therapy resistance. Interestingly, quiescent GBM cells upregulated epithelial-mesenchymal transition (EMT) genes and genes of extracellular matrix components. Our findings connect quiescent GBM cells with an EMT-like shift, possibly explaining how GBM stem cells achieve high therapy resistance and invasiveness, and suggest new targets to abrogate GBM. Overall design: Glioblastoma cancer cells in 3D organoid culture were pulsed for 2 weeks with H2B-GFP, then chased either 2 or 4 weeks. Label-retaining GFP-high cells (quiescent) were separated from bulk population, and both populations were analyzed by RNA-Seq.
Gene signatures of quiescent glioblastoma cells reveal mesenchymal shift and interactions with niche microenvironment.
Specimen part, Subject
View SamplesTo examine Ikaros tumor suppressor mechanisms, we have utilized inducible RNAi to dynamically restore endogenous Ikaros expression in BCR-ABL1+ B-ALL driven by its knockdown (Ikaros knockdown), and compared these tumors to tumors driven by BCR-ABL1 alone (control). Restoration of Ikaros causes rapid regression of tumor cells in vivo, significantly prolonging tumor transplant recipient survival. Using both transgenic and retroviral approaches, we conducted expression analysis of B-ALL by RNA-Seq and have identified a series of Ikaros-regulated genes within established tumor cell in vivo. Comparison of Ikaros-activated and Ikaros-repressed genes with human B-ALL expression data shows a set of conserved Ikaros target genes, some of which are associated with patient outcome (namely, CTNND1, IFITM3 and EMP1). Overall design: RNA-seq was performed on BCR-ABL1+ B-ALL with inducible Ikaros knockdown (Ikaros knockdown, n=8; transgenic n=5, retroviral n=3) or BCR-ABL1+ alone B-ALL (control, n=4; transgenic n=3, retroviral n=1) cells isolated from untreated and three 3-day Dox-treated mice. Samples were run on HiSeq or NextSeq platform. B-ALL B031 was run in technical duplicate. Extended Dox samples (B027: d7 and d10) and relapse samples for B027, B029 and B035 have also been analyzed in this dataset.
Conserved IKAROS-regulated genes associated with B-progenitor acute lymphoblastic leukemia outcome.
Specimen part, Treatment, Subject
View SamplesThe transcription factor STAT5 plays a critical role in B cell acute lymphoblastic leukemia (B-ALL). How STAT5 mediates this effect is unclear. Here we demonstrate that STAT5 activation cooperates with defects in the pre-BCR signaling components encoded by Blnk, Btk, Prkcb, Nfkb1, and Ikzf1 to initiate B-ALL. STAT5 antagonizes NF-B and IKAROS by opposing regulation of shared target genes. STAT5 binding was enriched at super-enhancers, which were associated with an opposing network of transcription factors, including PAX5, EBF1, PU.1, IRF4, and IKAROS. Patients with high ratios of active STAT5 to NF-B or IKAROS have more aggressive disease. Our studies illustrate that an imbalance of two opposing transcriptional programs drive B-ALL, and suggest that restoring the balance of these pathways may inhibit B-ALL.
Antagonism of B cell enhancer networks by STAT5 drives leukemia and poor patient survival.
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View SamplesPrimary human foreskin fibroblasts (HFF) were infected with wild-type simplex virus 1 (HSV-1) strain 17 at a multiplicity of infection (MOI) of 10. Newly transcribed RNA was labelled by adding 500µM 4-thiouridine (4sU) to the cell culture media for 1h. Total cellular RNA was isolated using Trizol. Newly transcribed RNA was purified following the protocol described in Raedle et al. JoVE 2013. Overall design: Newly transcribed RNA was labelled in one hour intervals during the first eight hours of HSV-1 infection. All nine 4sU-RNA samples as well as total cellular RNA of every second hour of infection were sent for sequencing. Two independent biological replicates were analysed.
Prediction of Poly(A) Sites by Poly(A) Read Mapping.
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