High Mobility Group protein mediated transcription requires DNA damage marker γ-H2AX
ABSTRACT: The eukaryotic genome is organized into chromatin, which constitutes the physiological template for DNA-dependent processes including replication, recombination, repair and transcription. Chromatin mediated transcription regulation involves histone modifications, chromatin remodeling and DNA methylation. However, the precise biological function of non-histone chromatin-associated proteins is still unclear. The high mobility group proteins are the most abundant non-histone chromatin-associated proteins. Here we combined proteomic, ChIP-seq and transcriptome data to decipher the mechanism of transcriptional regulation mediated by the high mobility group AT-hook protein 2 (HMGA2). We showed that HMGA2-induced transcription requires H2AX phosphorylation at S139 (H2AXS139ph; γ-H2AX), mediated by the kinase ataxia telangiectasia mutated (ATM). Furthermore, we demonstrated the relevance of this mechanism within the biological context of TGFB1-signaling. Our results link H2AXS139ph, a marker for DNA damage, to transcription, which is a new function for this histone modification. The interplay between HMGA2, ATM and H2AX is a novel mechanism of transcription initiation. Chip-seq data of HMGA2, H2AXS139ph and ATM obtained from Mouse embryonic Fibroblast cells in wt and Ko of Hmga2
Project description:DNA Double Strand Breaks (DSBs) are harmful lesions that require rapid detection and repair in order to avoid toxic genomic rearrangements. DSBs elicit the so called DNA Damage Response (DDR), largely relying on ataxia telangiectasia mutated (ATM) and DNA Protein Kinase (DNAPK), two members of the PI3K-like kinase family, whose respective functions during the sequential steps of the DDR remains controversial. Using the DIvA cell line, expressing the AsiSI restriction enzyme, we have investigated the role of ATM and DNAPK in several aspects of the DDR upon induction of multiple clean DSBs throughout the human genome. High resolution mapping revealed that they are activated and spread in cis on a confined region surrounding all DSBs, independently of the pathway used for repair. However, a thorough analysis of repair kinetics, H2AX domain establishment and H2AX foci structure and dynamics revealed non overlapping functions for the two kinases once recruited at DSBs. Our results suggest that ATM is not solely acting on chromatin marks but also on chromatin organisation in order to ensure repair accuracy and survival.
Project description:ATM drives DNA repair through rapid phosphorylation of the histone variant H2AX. Similarities between ATM and H2AX are evident in the phenotypes of their knockout mouse models, but the role of H2AX in the brain remains obscure. Here, we provide the first evidence that H2AX loss leads to neurobehavioral deficits. H2AX regulates proper response to oxidative stress through Nrf2-transcriptional targets and treatment with antioxidant ameliorates the neurobehavioral deficits. Overall design: 6 samples in total including 3 replicates of parental mouse embryonic fibroblasts (MEF) and 3 replicates of H2AX knockout MEF.
Project description:Jaiswal2017 - Cell cycle arrest
This model is described in the article:
ATM/Wip1 activities at
chromatin control Plk1 re-activation to determine G2 checkpoint
Jaiswal H, Benada J, Müllers E,
Akopyan K, Burdova K, Koolmeister T, Helleday T, Medema RH,
Macurek L, Lindqvist A.
EMBO J. 2017 Jul; 36(14):
After DNA damage, the cell cycle is arrested to avoid
propagation of mutations. Arrest in G2 phase is initiated by
ATM-/ATR-dependent signaling that inhibits mitosis-promoting
kinases such as Plk1. At the same time, Plk1 can counteract
ATR-dependent signaling and is required for eventual resumption
of the cell cycle. However, what determines when Plk1 activity
can resume remains unclear. Here, we use FRET-based reporters
to show that a global spread of ATM activity on chromatin and
phosphorylation of ATM targets including KAP1 control Plk1
re-activation. These phosphorylations are rapidly counteracted
by the chromatin-bound phosphatase Wip1, allowing cell cycle
restart despite persistent ATM activity present at DNA lesions.
Combining experimental data and mathematical modeling, we
propose a model for how the minimal duration of cell cycle
arrest is controlled. Our model shows how cell cycle restart
can occur before completion of DNA repair and suggests a
mechanism for checkpoint adaptation in human cells.
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Project description:GAGA associated transcription factor (GAF) is a highly abundant and essential protein in Drosophila. GAF recognizes and binds arrays of GA dinucleotides via a zinc finger DNA binding domain to regulate transcription by binding to general TF machinery or recruit nucleosome remodeling factors. We performed GAF ChIP-seq to quantify the intensity of GAF binding at high resolution in S2 cells. In addition, we performed GAF ChIP-seq in S2 cells that were depleted of GAF by RNAi. By quantifying the degree to which all GAF binding sites are susceptible to GAF depletion, we found the cellular degree of depletion does not translate equally to the depletion of GAF at individual chromatin bound sites. For example, some high intensity GAF binding sites were completely unaffected by GAF depletion, while lower affinity binding sites were often ablated upon GAF depletion. These data sets will serve as a valuable resource to others who study the dynamic interplay between GAF and chromatin. We also compared the GAF binding sites to the full set of genomic ChIP data that is available for S2 cells and compared the intensity for each factor and histone modification/variant. Lastly, we investigated the influence that GAF had upon inducible transcription factor binding using the heat shock system. A single mock immunoprecipitation (IP) using non-specific IgG was used as a background dataset for this study (see PMID: 20844575; GSM470838). We performed two independent GAF-ChIP-seq experiments in untreated S2 cells and two replicates in S2 cells that were depleted of GAF by RNAi.
Project description:Selective transcriptional activation and repression of genes throughout signaling cascades and development are poorly understood. Transcription factors (TF) orchestrate patterns and magnitude of transcriptional response, but TF action, or inaction, is highly dependent upon TF kinetics, distance from genes, chromatin architecture, and the local occupancy of other TFs. We integrated genomic transcription, chromosome looping, TF binding, and chromatin structure data to analyze the molecular cascade that results from estradiol-induced (E2) signaling in human MCF-7 breast cancer cells and addressed the context-specific nature of gene regulation. We analyzed kinetic ChIP-seq that profiled the master regulator of the E2-mediated response, estrogen receptor (ER), and found that transient ER binding sites are specifically associated with enhancers of repressed genes. We performed replicate ChIP-seq experiments prior to estrogen treatment and 2min, 5min, 10min, 40min, and 160min after E2 treatment.
Project description:Phosphorylation of histone H2AX is an early response to DNA damage in eukaryotes. In Saccharomyces cerevisiae, DNA damage or replication fork stalling results in histone H2A phosphorylation to yield gamma-H2A (yeast gamma-H2AX) in a Mec1 (ATR)- and Tel1 (ATM)- dependent manner. Here, we describe the genome-wide location analysis of gamma-H2A as a strategy to identify loci prone to engage the Mec1 and Tel1 pathways. Remarkably, gamma-H2A enrichment overlaps with loci prone to replication fork stalling and is caused by the action of Mec1 and Tel1, indicating that these loci are prone to breakage. Moreover, about half the sites enriched for gamma-H2A map to repressed protein-coding genes, and histone deacetylases are necessary for formation of gamma-H2A at these loci. Finally, our work indicates that high resolution mapping of gamma-H2AX is a fruitful route to map fragile sites in eukaryotic genomes. Overall design: To identify loci enriched in gamma-H2A, we carried out chromatin immunoprecipitations with a phospho-specific antibody that recognizes gamam-H2A in yeast and hybridized to high-density tiling arrays surveying the genome at an average density of one probe per 275 bp. In a typical experiment, we performed competitive hybridization of DNA precipitated from HTA1 HTA2 cells with DNA precipitated from the gamma-H2A-deficient hta1-S129A hta2-S129A cells (referred to hereafter as S129A). All experiments were done at least in duplicate and combined using a weighted average method.
Project description:In Saccharomyces cerevisiae, a single double-strand break (DSB) triggers extensive phosphorylation of histone H2A (known as gammaH2AX) over 50 kb on either side of the DSB. This modification is carried out by either of yeasts checkpoint kinases, the ATM homolog, Tel1, or the ATR homolog, Mec1. In G1-arrested cells, where there is very little 5 to 3 processing of DSB ends, only Tel1 promotes this modification. We have recently described a second modification gammaH2B - the phosphorylation of the C terminal T129 locus of histone H2B which is also carried out by both Mec1 and Tel1 kinases. To understand in detail how gamma-H2AX and gamma-H2B spread along the chromosome from a DSB we have undertaken a high-density analysis of their occupancy where there is a DSB on three different chromosomes. gamma-H2AX and gamma-H2B modifications are similar, but there is a marked absence of gamma-H2B near telomeres. We find that there is reduced gamma-H2AX and gamma-H2B modification over strongly transcribed regions, even taking into account the reduced histone occupancy of these genes. When transcription of the galactose-regulated genes GAL1, GAL10, GAL7 are turned off by the addition of glucose, gamma-H2AX is restored within 5 min; when these genes are again induced, gamma-H2AX is rapidly lost. Regions more distal to the GAL genes have markedly reduced gamma-H2AX levels that rise rapidly when transcription is repressed, suggesting that transcription acts as a barrier to the propagation of gamma-H2AX away from the DSB. The restoration of gamma-H2AX in transcribed regions can be carried out by either Mec1 or Tel1, even 7 h after break induction, suggesting that Tel1 remains associated with damaged chromosomes for an extended time. In addition, we show that gamma-H2AX can be transferred in trans, to regions unlinked to the DSB that lie in close proximity the DSB. Specifically, if a DSB is generated 14 kb from CEN2, gamma-H2AX is transferred to regions around all the other centromeres, in keeping with observed close proximity of all centromere-adjacent chromosome arms. This transfer can be observed even in the absence of formaldehyde crosslinking of the samples.
Project description:Phosphorylation of the histone variant H2AX forms γ-H2AX, which serves as a marker of DNA repair response. Here we provide ChIP-seq-based maps of histone H2AX, γ-H2AX, H2AZ, INO80, SRCAP, and RNA polymerase II in activated T cells. Matched data for H2AX and γ-H2AX in resting T cells and Jurkat cancer T cells are available in GSE25577. CD4+ T cells were stimulated in two different ways (IL-2 alone or IL-2 plus anti-CD3 and anti-CD28), and H2AX, γ-H2AX, H2AZ, INO80, and SRCAP profiles were examined by ChIP-seq
Project description:The high-mobility-group (HMG) proteins are the most abundant non-histone chromatin-associated proteins. Here we deciphered the role of the high mobility group AT-hook protein 2 (HMGA2) during lung development by analyzing the lung of Hmga2 deficient mice (Hmga2-/-).We found that Hmga2 is expressed in the mouse embryonic lung at the distal airways. Analysis of Hmga2-/- mice showed that Hmga2 is required for proper cell proliferation and distal epithelium differentiation during embryonic lung development. Hmga2 knockout (KO) led to enhanced canonical WNT signaling due to an increased expression of secreted WNT glycoproteins Wnt2b, Wnt7b and Wnt11 as well as a reduction of the WNT signaling antagonizing proteins GATA6 (GATA binding protein 6) and FZD2 (frizzled homolog 2). Comparison of Hmga2-/- with Hmga2+/+ mice by Affymetrix microarray-based expression analysis of embryonic lung revealed an increased expression of genes whose products participate in cell cycle and canonical Wnt signaling. Affymetrix microarray transcriptome analysis of Hmga2-/- and Hmga2+/+ embryonic lung (E18.5) was performed and analyzed
Project description:Carcinogenic bacteria, Helicobacter pylori, induce DNA double-strand breaks in infected host cells, while ATM-dependent DNA damage responses in host cells suppress genome instabilities caused by DNA breakages, which resulting in the suppression of H. pylori-induced gastric cancers. Although Helicobacter pylori infection is etiologically related to the inflammation-related malignancy, gastric cancers, it role in the molecular pathogenesis of disease remains unclear. In vitro studies have suggested the infection may cause breaks in double-stranded DNA. We used microarray analysis of H. pylori-infected human gastric biopsies to investigate the effect of H. pylori on gene expression genes involved in DNA repair and DNA damage response. Micro-array analysis and immunohistochemistory showed that ATM (ataxia-telangiectasia mutated) was upregulated in H. pylori gastritis but down regulated in the premalignant lesion, intestinal metaplasia. Studies in gastric cancer cell lines showed that H. pylori-infection induced activation of ATM and formation of γ-H2AX. γ-H2AX formation was present following infection with bout cag pathogenicity island (PAI)- positive and negative strains but more robust with cag PAI positive strains consistent with the fact that both cag PAI positive negative strains are associated with gastric cancer but the risk is higher with cag PAI positive strains. Eradication of H. pylori infection is associated with a reduction in cancer risk even in the most high risk populations. These data provide a plausible molecular mechanism for a direct bacterial-host interaction increasing cancer risk. To identify tumor suppressors affected by H. pylori-infection, microarray screening was used to compare the gene expression profiles of gastric mucosa obtained from individuals with H. pylori-gastritis and with intestinal metaplasia with tissue from uninfected controls.