ChipSeq of conditional knock-in mouse carrying the R178E (EE) mutation in exon 5 of the endogenous mouse Trp53 gene locus.
ABSTRACT: The mouse R178E (EE) mutation of the Trp53 is a p53 mutant protein with native conformation that lacks the ability to form tetramers and thus constitutes a mutant form of p53 that lacks DNA binding cooperativity. Here we want to assess DNA binding ability of the EE mutant in MEFs under untreated conditions and following p53 stabilization with the Mdm2 inhibitor nutlin-3a and compare it to p53 KO and WT mice.
Project description:ChIP-chip study using Saos-2 cell line infected with adenoviruses encoding GFP (Mock) or GFP together with the p53 H1 helix mutants EL or RE. DNA-protein-complexes were precipitated with monoclonal p53-antibody (clone DO-1). Mock-chromatin was immunoprecipitated in the absence of antibody.<br>Three completely independent biological replicates were performed for each antibody, obtaining the corresponding input as total genomic DNA reference. Hybridizations were performed using Affymetrix GeneChip Human Tiling 2.0R Array set (7 arrays set).<br><br> Affymetrix .BAR files and an additional processed data file containing the coordinates of the identified binding sites can be found in the FTP directory for this experiment. <A HREF="ftp://ftp.ebi.ac.uk/pub/databases/microarray/data/experiment/MEXP/E-MEXP-1748">FTP directory</A>
Project description:Epstein-Barr-Virus (EBV) Nuclear Antigens EBNALP and EBNA2 are co-expressed in EBV infected B-lymphocytes and are critical for Lymphoblastoid Cell Line (LCL) growth. EBNALP removes NCOR1 and RBPJ repressive complexes from promoter and enhancer sites and EBNA2 mostly activates transcription from distal enhancers. ChIP-seqs found EBNALP at 19,224 LCL sites, which were 33% promoter associated. EBNALP was associated with 10 transcription factor (TF) clusters that included YY1(63%), SP1(62%), PAX5(59%), BATF(50%), IRF4(49%), RBPJ(43%), ETS1(39%), PU.1(37%), RAD21(33%), NF-kB(31%), TBLR1(26%), ZNF143(24%), CTCF(23%), SMC3(21%), and EBF(17%). EBNALP sites had higher H3K4me3, H3K9ac, H3K27ac, H2Az, and RNA Pol II signals than EBNA2 sites and had similar transcription effects. EBNALP co-localized with 29% of 19,845 EBNA2 sites. EBNALP/EBNA2 sites were similar to EBNALP sites in promoter localization, associated cell TFs, Pol II, H3K4me3, H3K9ac, H3K27ac, and H2Az signals. EBNALP and EBNA2 promoter sites were more transcriptionally active than EBNALP or EBNA2 promoter sites. EBNALP was at the enhancer or promoter of myc and MYC affected genes, including cyclin D2, and bcl2. EBNALP at promoters with DNA looping and transcription factors, is positioned to deplete repressors from enhancers and promoters, enable chromatin remodeling, and transcription activation. Two EBNALP ChIP-seq replicates from IB4 LCL are analyzed in this study.
Project description:H3-ChIP-seq was performed in order to analyze changes in nucleosomal occupancy after depletion of CTCF/P190 and ISWI from Drosophila S2 cells Histone H3 ChIP-seq from Drosophila S2 cells after CTCF/CP190 or ISWI-specific RNAi treatment
Project description:Transcription factor-induced reprogramming of somatic cells to pluripotency is a very inefficient process, probably due to the existence of important epigenetic barriers that are imposed during differentiation and that contribute to preserve cell identity. In an effort to decipher the molecular nature of these barriers, we followed a genome-wide approach, in which we identified macro histone variants (macroH2A) as highly expressed in human somatic cells but downregulated after reprogramming to pluripotency, as well as strongly induced during differentiation. Knock down of macro histone variants in human keratinocytes increased the efficiency of reprogramming to pluripotency, while overexpression had opposite effects. Genome-wide occupancy profiles show that in human keratinocytes macroH2A.1 preferentially occupies genes that are expressed at low levels and are marked with H3K27me3, including pluripotency-related genes and bivalent developmental regulators, at which its presence prevents the regain of H3K4me2 during reprogramming, over imposing an additional layer of repression that preserves cell identity. Gemone wide occupancy of HA:macroH2A.1 in human keratinocytes
Project description:Bacterial toxin-antitoxin systems (TASs) are thought to respond to various stresses, often inducing growth-arrested (persistent) sub-populations of cells whose housekeeping functions are inhibited. However, it is not always clear whether specific targets of orthologous RNAse toxins are responsible for their phenotypic effect, which has made it difficult to accurately place the multitude of TASs within cellular and adaptive regulatory networks. Here we show that the TAS HigBA can promote and inhibit bacterial growth dependent on the dosage of HigB, a toxin regulated by the DNA damage (SOS) repressor LexA in addition to its antitoxin HigA, and the target selectivity of HigB’s mRNA cleavage activity. HigB reduced the expression of an efflux pump that is toxic to a polarity control mutant, cripples the growth of cells lacking LexA and targets the cell cycle circuitry. Thus, TASs can have outcome switching activity in bacterial adaptive (stress) and systemic (cell cycle) networks. DNA binding of the antitoxin HigA and the SOS regulator LexA was analysed by chromatin immunoprecipitation-deep sequencing, and found to overlap at only one locus, the HigBA TA system promoter
Project description:Tumor suppressor p53 regulates various role in the cell including cell cycle arrest, DNA repair and apoptosis. Current research achieved to investigate p53 target genes in human osteosarcoma cell line-SaOS2 cell. Examination of p53 binding protein by transfecting flag-tagged wild type p53 into SaOS2 cells.
Project description:We report that ancestral zinc-finger-domain transcriptional regulators, previously reported to control virulence/symbiosis, implement a cell cycle (S→G1) transcriptional switch. To unravel how this G1-phase transcriptional program is reinstated during a primitive cell cycle, we first defined G1-specific promoters in the model bacterium Caulobacter crescentus by comparative ChIP-Seq analysis. We then exploited one such promoter as genetic proxy, to identify two conserved developmental regulator paralogs, MucR1/2, that constitute a quadripartite and homeostatic regulatory module directing the switch from S→G1-phase transcription. Surprisingly, MucR orthologs that regulate virulence and symbiosis gene transcription in Brucella, Agrobacterium or Sinorhizobium support the G1 transcriptional switch in Caulobacter. Pan-genomic ChIP-Seq analyses in Sinorhizobium and Caulobacter show that this module targets orthologous genes. Thus, this ancestral bacterial lineage from which eukaryotic organelles descended may coordinate virulence/symbiosis with other cell cycle functions using a primordial transcription factor fold that is now primarily found in the eukaryotic domain of life. Examination of 5 transcripton factor binding in two different species
Project description:An ability to sense and respond to changes in extracellular phosphate is critical to the survival of most bacteria. For Caulobacter crescentus, which typically lives in phosphate-limited environments, this process is especially crucial. Like many bacteria, Caulobacter responds to phosphate limitation through a conserved two-component signaling pathway called PhoR-PhoB, but the direct regulon of PhoB in this organism is unknown. Here, we use ChIP-Seq to map the global binding patterns of the phosphate-responsive transcriptional regulator PhoB in both phosphate-limited and -replete conditions. Combined with genome-wide expression profiling, our work demonstrates that PhoB is induced to regulate nearly 50 genes in phosphate-starved conditions. The PhoB regulon is comprised primarily of genes known or predicted to help Caulobacter scavenge for and import inorganic phosphate, including 15 different membrane transporters. We also investigated the regulatory role of PhoU, a widely conserved protein proposed to coordinate phosphate import with expression of the PhoB regulon by directly modulating the histidine kinase PhoR. However, our studies show that it likely does not play such a role in Caulobacter as depleting PhoU has no significant effect on PhoB-dependent gene expression. Instead, cells lacking PhoU exhibit a striking accumulation of large polyphosphate granules suggesting that PhoU participates in controlling intracellular phosphate metabolism. An allele of phoB bearing a C-terminal 3x-flag tag was integrated at its native locus, and ChIP followed by deep sequencing on Illumina MiSeq was performed on samples grown in rich medium, phosphate-limited medium, and in a pstS::Tn5 mutant background in rich medium.
Project description:Identification and characterization of HP1BP3 (a human histone H1 homologue) as a novel chromatin retention factor essential for the co-transcriptional processing of pri-miRNA. We generated BAC transgenic cells at 80% confluency (~1x107) were cross-linked with 1% formaldehyde for 10 minutes at 37°C, and quenched with 125 mM glycine at room temperature for 5 minutes. The fixed cells were washed twice with cold PBS, scraped, and transferred into 1 ml PBS containing protease inhibitors (Roche). After centrifugation at 700 g for 4 minutes at 4°C, the cell pellets were resuspended in 100 μl ChIP lysis buffer (1% SDS, 10 mM EDTA, 50 mM Tris-HCl [pH 8.1] with protease inhibitors) and sonicated at 4°C with a Bioruptor (Diagenode) (30 seconds ON and 30 seconds OFF at highest power for 15 minutes). The sheared chromatin with a fragment length of ~200 – 600 bp) was centrifuged at 20,000 g for 15 minutes at 4°C). 100 μl of the supernatant was used for ChIP or as input. A 1:10 dilution of the solubilized chromatin in ChIP dilution buffer (0.01% SDS, 1.1% Triton X-100, 1.2 mM EDTA, 167 mM NaCl 16.7 mM Tris-HCl [pH 8.1]) was incubated at 4°C overnight with 6 μg/ml of a goat anti-GFP (raised against His-tagged full-length eGFP and affinity-purified with GST-tagged full-length eGFP). Immunoprecipitation was carried out by incubating with 40 μl pre-cleared Protein G Sepharose beads (Amersham Bioscience) for 1 hour at 4°C, followed by five washes for 10 minutes with 1ml of the following buffers: Buffer I: 0.1% SDS, 1% Triton X-100, 2 mM EDTA, 20 mM Tris-HCl [pH 8.1], 150 mM NaCl; Buffer II: 0.1% SDS, 1% Triton X-100, 2 mM EDTA, 20 mM Tris-HCl [pH 8.1], 500 mM NaCl; Buffer III: 0.25 M LiCl, 1% NP-40, 1% deoxycholate, 1 mM EDTA, 10 mM Tris-HCl [pH 8.1]; twice with TE buffer [pH 8.0]. Elution from the beads was performed twice with 100 μl ChIP elution buffer (1% SDS, 0.1 M NaHCO3) at room temperature (RT) for 15 minutes. Protein-DNA complexes were de-crosslinked by heating at 65°C in 192 mM NaCl for 16 hours. DNA fragments were purified using QiaQuick PCR Purification kit (QIAGEN) and eluted into 30 μl H2O according to the manufacturer’s protocol after treatment with RNase A and Proteinase K.
Project description:Regulation of gene expression by chromatin modification through methylation of histone lysine residues is a dynamic, reversible process that when deregulated is associated with cancer development. In multiple myeloma, combined inhibition of the histone demethylases JARID1B, UTX and JmjD3 by the small molecule GSK-J4 prevents cellular glutamine utilization leading to amino acids deprivation, activates the integrated stress response via GCN2-dependent ATF4 activation, and induces apoptosis. This response is associated with a profound upregulation of metallothionein genes. Combined with clinical data demonstrating that overexpression of JARID1B is associated with shorter survival in multiple myeloma patients, this study highlights histone demethylases as epigenetic drug targets and places this demethylase inhibitor chemotype as having unique potential relative to established anti-myeloma treatment options. In total there are 7 different samples analyzed and one input control. Treatments are carried out with the demethylase inhibitor (or DMSO as negative control) at 6h and 48h, or with LNA targeting demethylases (or scrambled LNA) at 7 days. A negative control at 0h is included.