Genome-wide map of GATA6 DNA binding in human CRC cells
Ontology highlight
ABSTRACT: We describe the genome-wide DNA-binding of GATA6 in a human CRC cell line (LS174T). GATA6 is found to bind the promoter of genes involved in the maintenance of intestinal stem cells, including genes of the Wnt and TGFbeta/BMP pathways. With this we describe a novel GATA6-dependent mechanism of stem cell maintenance in colorectal tumors. Examination of GATA6 binding and H3K4me1, H3K4me3 and H3K27ac levels in a human CRC cell line by Chromatin immunoprecipitation followed by deep sequencing.
Project description:By studying a mouse model, as well as human tumors samples and cell lines, we have revealed a tumor suppressive role for Gata6 in the pathogenesis of pancreatic ductal adenocarcinoma (PDAC). In order to understand the mechanism underlying such tumor suppressive function, we analyzed the genome-wide DNA-binding of GATA6 in a human PDAC cell line (PaTu8988S). GATA6 is found to bind the promoter of genes involved in the epithelial differentiation programme, as well as of genes involved in the mesenchymal programme. With this we describe a novel GATA6-dependent mechanism of regulation of EMT. Examination of GATA6 binding to the DNA in a human PDAC cell line
Project description:We have previously described in mouse models that pancreas-specific deletion of Gata6 results in pancreas alterations by rendering pancreatic acinar cells in a non-fully differentiation state, and furthermore it accelerates tumor initiation and progression in a pro-tumorigenic context (KrasG12V expression). We aim to determine the sites where Gata6 binds at the genome-wide level in the pancreas to unveil why its loss leads to altered pancreatic function and enhanced tumor formation when coexpressed with KrasG12V. Gata6 ChIP-Seq in the mouse pancreas
Project description:We report the global gene expression of mouse pancreatic cells in a pancreas-specific conditional knock-out mouse for Gata6, as compared with age-matched controls. Total RNA was extracted from the pancreas of 6-8 -week old mice of the two genotypes and analyzed. at this age, Gata6P-/- pancreata are histologically normal, but the acinar differentiation programme is already altered. we observe that loss of Gata6 causes the de-repression of ectopic non-pancreatic genes, as well as some genes involved in the mesenchymal programme. mRNA extracted from the pancreas of 4 controls and 4 Gata6P-/- mice was sequenced.
Project description:We studied the chromatin modification patterns induced by the presence of the MLL-AF9 fusion protein in a model of human hematopoietic stem/progenitor cells (HSPC) transduced with retrovirus expressing MLL-AF9cDNA (HSPC-MA9). Comparative ChIP-seq analysis between HSPC-MA9 and control HSPC, revealed a massive hyperacetylation of histones that was consistent with the transcriptional profile in the presence of MLL-AF9 fusion protein. Furthermore, we identified 66 MLL-AF9 targets, and found that H4ac was present along with H3K4me3 and H3K79me2 chromatin marks in over 50% of the MLL-AF9 target genes. Examination of histone aceylation and methylation changes upon expression of MLL-AF9 fusion protein in human hematopoietic stem/progenitor cells.
Project description:The c-MYC oncogene is a key transcription factor deregulated in most human tumors. Histone marks associated with transcriptionally active genes in euchromatic islands define the set of high-affinity c-MYC targets. The mechanisms involved in their recognition by c-MYC are not known but likely involve chromatin-remodelling and chromatin-modifying complexes. Here, we show that c-MYC interacts with BPTF, a core subunit of the NURF complex that binds active chromatin. BPTF is required for the activation of the full c-MYC transcriptional programme in fibroblasts. BPTF knockdown leads to a decrease in c-MYC recruitment to DNA and to changes in chromatin accessibility. Using BPTF-null MEFs we show that BPTF is necessary for c-MYC-driven proliferation, G1-S progression, and replication stress, but not for c-MYC-driven apoptosis. Consistently, BPTF is required for the proliferation of cells driven by c-MYC, such as Burkitt lymphoma, and its expression in human cancer lines correlates with the activation of c-MYC gene signatures. Our findings point to the c-MYC-BPTF axis as a potential therapeutic target in cancer. To assess whether BPTF is required for the transcriptional activity of c-MYC, human foreskin fibroblasts (HFF) were stably transduced with the chimeric MYC-ER cDNA (HFF MYC-ER) and infected with lentiviruses coding for either control (shNt) or BPTF-targeting shRNAs. Cells were serum-starved for 2 days to achieve quiescence and then treated with 4-hydroxytamoxifen (4-OHT)
Project description:LID is a histone demethylase acting on H3K4me3, a mark related to transcription and found near the transcription start sites (TSS) of the genes. We analyzed where POLIISER5 and POLIISER2 are localized in LID RNAi mutants. 1 sample for POLIISER5 with an input control, and 1 sample for POLIISER2 with an input control.
Project description:Transcription factors are often regarded as being comprised of a DNA-binding domain and a functional domain. The two domains are considered separable and autonomous, with the DNA-binding domain directing the factor to its target genes and the functional domain imparting transcriptional regulation. We have examined a typical Zinc Finger (ZF) transcription factor from the Krüppel-like factor (KLF) family, KLF3. This factor has an N-terminal repression domain that binds the co-repressor C-terminal binding protein (CtBP), and a DNA-binding domain composed of three classical (ZFs) at its C-terminus. We established a system to compare the genomic occupancy profile of wildtype KLF3 with two mutants affecting the N-terminal functional domain: a mutant unable to contact its cofactor CtBP and a mutant lacking the entire N-terminal domain, but retaining the ZFs intact. We used chromatin immunoprecipitation followed by sequencing (ChIP-seq) to assess binding across the genome in murine embryonic fibroblasts. Our results define the in vivo recognition site for KLF3 and the two mutants as a typical CACCC-like element. Unexpectedly, we observe that mutations in the N-terminal functional domain severely affect DNA binding. In general, both mutations reduce binding but there are also instances where binding is retained or even increased. These results provide a clear demonstration that the correct localization of transcription factors to their target genes is not solely dependent on their DNA-contact domains. This informs our understanding of how transcription factors operate and is of relevance to the design of artificial ZF proteins. ChIP-seq was performed on the three samples, KLF3, ΔDL and DBD in duplicate (biological replicates). Input samples were used as controls.
Project description:Cohesin, which consists of SMC1, SMC3, Rad21 and either SA1 or SA2, topologically embraces the chromatin fibers to hold sister chromatids together and to stabilize chromatin loops. Increasing evidence indicates that these loops are the organizing principle of higher-order chromatin architecture, which in turn is critical for gene expression. To determine how cohesin contributes to the establishment of tissue-specific transcriptional programs, we compared genome-wide cohesin distribution, gene expression and chromatin architecture in cerebral cortex and pancreas from adult mice. More than one third of cohesin binding sites differ between the two tissues and these are enriched at the regulatory regions of tissue-specific genes. Cohesin colocalizes extensively with the CCCTC-binding factor (CTCF). Cohesin/CTCF sites at active enhancers and promoters contain, at least, cohesin-SA1 whereas either cohesin-SA1 or cohesin-SA2 are present at active promoters independently of CTCF. Analyses of chromatin contacts at the Protocadherin gene cluster and the Regenerating islet-derived (Reg) gene cluster, mostly expressed in brain and pancreas respectively, revealed remarkable differences in the architecture of these loci in the two tissues that correlate with the presence of cohesin. Moreover, we found decreased binding of cohesin and reduced transcription of the Reg genes in the pancreas of SA1 heterozygous mice. Given that Reg proteins are involved in the control of inflammation in pancreas, such reduction may contribute to the increased incidence of pancreatic cancer reported in these animals. Examination of the relationship between gene expression, genome wide cohesin distribution and chromatin structure