Project description:Mapping ultra high resolution of Brachyury:DNA interaction would provide us with valuable new mechanistic insights into complex molecular transactions at Brachyury-bound enhancers. Embryonic stem cells were differentiated into Brachyury-positive mesoendoderm cells. And, ChIP-exo experiment was then performed to identify detailed Brachyury-DNA binding profiles.
Project description:To gain new mechanistic insights into highly-regulated lineage specification and morphogenetic processes during early embryogenesis, we applied ChIP-seq to identify transcriptional programs mediated by a key developmental regulator - Brachyury. Embryonic stem cells were differentiated into Brachyury-positive mesoendoderm cells. And, ChIP-seq experiments were carried out by two independent Brachyury antibodies.
Project description:Chromatin-organizing factors, like CTCF and cohesins, have been implicated in the control of complex viral regulatory programs. We investigated the role of CTCF and cohesin in the control of the latent to lytic switch for Kaposi's Sarcoma-Associated Herpesvirus (KSHV). We found that cohesin subunits, but not CTCF, were required for the repression of KSHV immediate early gene transcription. Depletion of cohesin subunits Rad21, SMC1, or SMC3 resulted in lytic cycle gene transcription and viral DNA replication. In contrast, depletion of CTCF failed to induce lytic transcription or DNA replication. ChiP-Seq analysis revealed that cohesins and CTCF bound to several sites within the immediate early control regions for ORF50 and more distal 5' sites that also regulate the divergently transcribed ORF45-46-47 gene cluster. Rad21 depletion led to a robust increase in ORF45 and ORF47 transcripts, with similar kinetics to that observed with chemical induction by sodium butyrate. During latency, the chromatin between the ORF45 and ORF50 transcription start sites was enriched in histone H3K4me3 with elevated H3K9ac at the ORF45 promoter and elevated H3K27me3 at the ORF50 promoter. A paused form of RNA pol II was loosely associated with the ORF45 promoter region during latency, but was converted to an active elongating form upon reactivation induced by Rad21 depletion. Butyrate-induced transcription of ORF45 and ORF47 was resistant to cyclohexamide, suggesting that these genes have immediate early features similar to ORF50. Butyrate-treatment caused the rapid dissociation of cohesins and loss of CTCF binding at the immediate early gene locus, suggesting that cohesins may be a direct target of butyrate-mediated lytic induction. Our findings implicate cohesins as a major repressor of KSHV lytic gene activation, and function coordinately with CTCF to regulate the switch between latent and lytic gene activity. Study of chromatin-organizing factors, like CTCF and cohesins.
Project description:These ChIP-exo data were used to validate the predictions from our live-cell single-molecule imaging experiment The ChIP-exo mapping of ultra-fine localization of endogenous Sox2, halo-Sox2, and two halo-Sox2 mutants (halo-Sox2M and halo-Sox2D) in embryonic stem cells.
Project description:Mapping ultra-high resolution of Sp1:DNA interaction would provide us with valuable new mechanistic insights into Sp1-mediated gene regulatory network in Huntington Disease cell culture model. STHdh Q7/Q7 cells were directly fixed and used for the ChIP-exo experiment.
Project description:The Wnt3a/?-catenin and Activin/Smad2,3 signaling pathways synergize to induce endodermal differentiation of human embryonic stem cells, however the mechanism is not well-understood. Using ChIP-seq and GRO-seq analyses, we report here that hESC enhancers, including Wnt3a/LEF-1 sites, hold enhancer RNAPII complexes (eRNAPII) containing high levels of Ser5P and low Ser7P. In Wnt3a signaling, ?-catenin recruits cohesin to the LEF-1:eRNAPII sites to induce enhancer-promoter looping and activate transcription of mesoendodermal (ME) genes. However, paused Ser5P-RNAPII complexes accumulate at these genes, indicating that elongation remains limiting. Subsequent Activin/Smad2,3 signaling increases P-TEFb occupancy, CTD-Ser7P, and productive elongation at ME genes. Additionally, ME genes, including EOMES and MIXL1, are repressed by the Hippo regulator, Yap1, an essential pluripotency factor. GRO-seq experiments indicate that Yap1 blocks nascent transcription and controls NELF occupancy on ME genes. Thus, Wnt3a/?-catenin and Activin/Smad2,3 pathways up-regulate transcription initiation and elongation, respectively, to overcome Yap1 repression during early hESC differentiation ChIP-seq and GROseq experiments in H1 hESCs. Cells were treated with Wnt3a (200ng/ml), Activin A (100ng/ml) or Wnt3a+Activin A (W200ng/ml+A100ng/ml) for 4h (ChIP-seq) or 6h (GRO-seq). GRO-seq in YAP depleted cells were carried out following transfection with control or YAP siRNAs . After 48h transfection, cells were left untreated or treated with Wnt3a+Activin (W200ng/ml+A100ng/ml) for additional 6h.
Project description:The transcription factor BRACHYURY (T, BRA) is one of the first markers of gastrulation and lineage specification in mammals. Despite its wide use and importance in stem cell and developmental biology, its genomic targets are largely unknown. Here, we used differentiated human embryonic stem cells to study the role of BRA in Bmp4-induced mesoderm and Activin-induced endoderm progenitors by ChIP-seq. We show that BRA has distinct genome-wide binding landscapes in these two populations. Our data illuminate the function of BRA in the context of human embryonic development and show that the regulatory role of BRA is context-dependent. ChIP-seq of BRACHYURY (T, BRA) in two cell types: endoderm and mesoderm progenitors derived from human embryonic stem cells after 36 hours of growth in chemically-defined media (described in Bernardo et al., Cell Stem Cell, 2011, 9:144-155). Input DNA samples are included as a control.
Project description:BACKGROUND: The polycomb group protein Ezh2 is an epigenetic repressor of transcription originally found to prevent untimely differentiation of pluripotent embryonic stem cells. We previously demonstrated that Ezh2 is also expressed in multipotent neural stem cells (NSCs). We showed that Ezh2 expression is downregulated during NSC differentiation into astrocytes or neurons. However, high levels of Ezh2 remained present in differentiating oligodendrocytes until myelinating. This study aimed to elucidate the target genes of Ezh2 in NSCs and in premyelinating oligodendrocytes (pOLs). METHODOLOGY/PRINCIPAL FINDINGS: We performed chromatin immunoprecipitation followed by high-throughput sequencing to detect the target genes of Ezh2 in NSCs and pOLs. We found 1532 target genes of Ezh2 in NSCs. During NSC differentiation, the occupancy of these genes by Ezh2 was alleviated. However, when the NSCs differentiated into oligodendrocytes, 393 of these genes remained targets of Ezh2. Analysis of the target genes indicated that the repressive activity of Ezh2 in NSCs concerns genes involved in stem cell maintenance, in cell cycle control and in preventing neural differentiation. Among the genes in pOLs that were still repressed by Ezh2 were most prominently those associated with neuronal and astrocytic committed cell lineages. Suppression of Ezh2 activity in NSCs caused loss of stem cell characteristics, blocked their proliferation and ultimately induced apoptosis. Suppression of Ezh2 activity in pOLs resulted in derangement of the oligodendrocytic phenotype, due to re-expression of neuronal and astrocytic genes, and ultimately in apoptosis. CONCLUSIONS/SIGNIFICANCE: Our data indicate that the epigenetic repressor Ezh2 in NSCs is crucial for proliferative activity and maintenance of neural stemness. During differentiation towards oligodendrocytes, Ezh2 repression continues particularly to suppress other neural fate choices. Ezh2 is completely downregulated during differentiation towards neurons and astrocytes allowing transcription of these differentiation programs. The specific fate choice towards astrocytes or neurons is apparently controlled by epigenetic regulators other than Ezh2. Examination of Ezh2 target sites in 2 different primary cells types
Project description:Affinity and dose of T cell receptor (TCR) interaction with antigens govern the magnitude of CD4+ T cell responses, but questions remain regarding the quantitative translation of TCR engagement into downstream signals. We find that while the response of CD4+ T cells to antigenic stimulation is bimodal, activated cells exhibit analog responses proportional to signal strength. Gene expression output reflects TCR signal strength, providing a signature of T cell activation. Expression changes rely on a pre-established enhancer landscape and quantitative acetylation at AP-1 binding sites. Finally, we show that graded expression of activation genes depends on ERK pathway activation, suggesting that an ERK-AP-1 axis translates TCR signal strength into proportional activation of enhancers and genes essential for T cell function. CD4+ T cells from transgenic AND mice were sequenced under the conditions indicated. Replicates are included for each type of data (RNA-Seq, ChIP-Seq), and are numbered accordingly. The No Peptide condition serves as the untreated control for the peptide-treated samples, and inputs are provided for ChIP-Sequencing samples.
Project description: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.