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Cohesin protects genes against ?H2AX Induced by DNA double-strand breaks.

ABSTRACT: Chromatin undergoes major remodeling around DNA double-strand breaks (DSB) to promote repair and DNA damage response (DDR) activation. We recently reported a high-resolution map of ?H2AX around multiple breaks on the human genome, using a new cell-based DSB inducible system. In an attempt to further characterize the chromatin landscape induced around DSBs, we now report the profile of SMC3, a subunit of the cohesin complex, previously characterized as required for repair by homologous recombination. We found that recruitment of cohesin is moderate and restricted to the immediate vicinity of DSBs in human cells. In addition, we show that cohesin controls ?H2AX distribution within domains. Indeed, as we reported previously for transcription, cohesin binding antagonizes ?H2AX spreading. Remarkably, depletion of cohesin leads to an increase of ?H2AX at cohesin-bound genes, associated with a decrease in their expression level after DSB induction. We propose that, in agreement with their function in chromosome architecture, cohesin could also help to isolate active genes from some chromatin remodelling and modifications such as the ones that occur when a DSB is detected on the genome.

SUBMITTER: Caron P

PROVIDER: S-EPMC3261922 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Cohesin protects genes against γH2AX Induced by DNA double-strand breaks.

Caron Pierre P Aymard Francois F Iacovoni Jason S JS Briois Sébastien S Canitrot Yvan Y Bugler Beatrix B Massip Laurent L Losada Ana A Legube Gaëlle G

PLoS genetics 20120119 1

Chromatin undergoes major remodeling around DNA double-strand breaks (DSB) to promote repair and DNA damage response (DDR) activation. We recently reported a high-resolution map of γH2AX around multiple breaks on the human genome, using a new cell-based DSB inducible system. In an attempt to further characterize the chromatin landscape induced around DSBs, we now report the profile of SMC3, a subunit of the cohesin complex, previously characterized as required for repair by homologous recombinat ...[more]

PMID: 22275873

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Project description:FOXO3a (forkhead box transcription factor 3a) is involved in regulating multiple biological processes in cancer cells. BNIP3 (Bcl-2/adenovirus E1B 19-kDa-interacting protein 3) is a receptor accounting for priming damaged mitochondria for autophagic removal. In this study we investigated the role of FOXO3a in regulating the sensitivity of glioma cells to temozolomide (TMZ) and its relationship with BNIP3-mediated mitophagy. We showed that TMZ dosage-dependently inhibited the viability of human U87, U251, T98G, LN18 and rat C6 glioma cells with IC50 values of 135.75, 128.26, 142.65, 155.73 and 111.60 μM, respectively. In U87 and U251 cells, TMZ (200 μM) induced DNA double strand breaks (DSBs) and nuclear translocation of apoptosis inducing factor (AIF), which was accompanied by BNIP3-mediated mitophagy and FOXO3a accumulation in nucleus. TMZ treatment induced intracellular ROS accumulation in U87 and U251 cells via enhancing mitochondrial superoxide, which not only contributed to DNA DSBs and exacerbated mitochondrial dysfunction, but also upregulated FOXO3a expression. Knockdown of FOXO3a aggravated TMZ-induced DNA DSBs and mitochondrial damage, as well as glioma cell death. TMZ treatment not only upregulated BNIP3 and activated autophagy, but also triggered mitophagy by prompting BNIP3 translocation to mitochondria and reinforcing BNIP3 interaction with LC3BII. Inhibition of mitophagy by knocking down BNIP3 with SiRNA or blocking autophagy with 3MA or bafilomycin A1 exacerbated mitochondrial superoxide and intracellular ROS accumulation. Moreover, FOXO3a knockdown inhibited TMZ-induced BNIP3 upregulation and autophagy activation. In addition, we showed that treatment with TMZ (100 mg·kg-1·d-1, ip) for 12 days in C6 cell xenograft mice markedly inhibited tumor growth accompanied by inducing FOXO3a upregulation, oxidative stress and BNIP3-mediated mitophagy in tumor tissues. These results demonstrate that FOXO3a attenuates temozolomide-induced DNA double strand breaks in human glioma cells via promoting BNIP3-mediated mitophagy.

Project description:This series is a supplementary data set for the manuscript titled "Postreplicative recruitment of Cohesin to double-strand breaks is required for DNA repair" All data shown in the paper plus duplicate experiments were registered (15 ChIP-chip data). Experimental design: 1. Type of experiment: ChIP (Chromatin immunoprecipitation) analysis hybridized to high density oligonucleotide arrays. The S. cerevisiae chromosome VI array described by Katou et al. (2003) Nature 424, 1078-83 and the newly developed S. cerevisiae chromosomes III-VIa have been used. 2. Experimental factors: Distribution of the sister chromatid cohesion protein Scc1, before and after induction of a DNA double strand break (dsb) on chromosome III, V and VI in G2/metaphase cells were analysed (Benomyl arrested cells). 3. Number of hybridizations performed: ChIP analysis: 15 4. Hybridisation design: ChIP analysis: comparison of ChIP fraction with SUP (supernatant) fraction 5. Quality control: Duplication of experiments, confirmation of recruitment of the analysed protein to a dsb by induction of breaks at three different positions in the genome. Mock hybridisation of samples immunoprecipitated from cells containing no tag recognized by antibody used. Checking of the ChIP fraction by Western blotting. 6. URL of supplemental website: GEO Accession number: GSE1905 Web site: http://chromosomedynamics.bio.titech.ac.jp Samples used, extract preparation and labeling: 1. Origin of the biological sample Budding yeast (Saccharomyces cerevisiae). 2. Manipulation of the samples and the protocols used: Mitotic budding yeast cells were synchronised in G2/M with Benomyl (80 ug/ml) Cells were fixed 30 minutes at room temperature plus over night in 1% formaldehyde at 4C. 3. Protocols for preparing extracts: ChIP analysis: Extract preparation was processed following the Shirahige lab protocol (http://chromosomedynamics.bio.titech.ac.jp ). 5x10^8 cells were disrupted using Multi-Beads Shocker (MB400U, YASUI KIKAI, Osaka). Whole cell extract was sonicated to obtain 400-600 bp genomic DNA fragments. Anti-Flag monoclonal antibody M2 (Sigma-Aldrich Co., St Louis, MO) coupled to Dynabeads (Dynal, protein A Dynabeads) were used for chromatin immunoprecipitation. The immunprecipates were eluted and incubated over night at 65Â¨Â¬C to reverse the cross-link. Immunoprecipitated genomic DNA was incubated with proteinase K, extracted 2 times with phenol/chloroform/isoamylalcohol, precipitated, resuspended in TE and incubated with RnaseA. The DNA was then purified using the Qiagen PCR purification kit, and concentrated by ethanol precipitation. The DNA was amplified by PCR after random priming. 10 ug of amplified DNA was digested with Dnase I to a mean size of 100 bp. After Dnase I inactivation at 95Â¨Â¬C, fragments were labelled as detailed below. 4. Labeling protocol DNA fragments were end-labeled by addition of 25 U of Terminal Transferase and 1 nmol Biotin-N6ddATP (NEN) for 1 hour at 37C as previously described by Winzeler et al. (Science. 281, 1194-1197, 1998). The entire sample was used for hybridization. 5. Hybridization procedures and parameters: Hybridization, blocking and washing were carried out as previously described (http://chromosomedynamics.bio.titech.ac.jp). Each sample was hybridized to the array in 150 ul containing 6xSSPE; 0.005% TritonX-100; 15 ug fragmented denatured salmon sperm DNA (Gibco-BRL); 1 nmole 3â??biotin labelled control oligonucleotide (oligo B2, Affymetrix). Samples were denatured at 100C for 10 minutes, and then put on ice before being hybridized for 16 hours at 42C in an hybridization oven (GeneChip Hybri. Oven 320, Affymetrix). Washing and scanning protocol (FlexMidi-euk2v3-450) provided by Affymetrix was performed automatically on a fluidics station (GeneChip fluidics station 400, Affymetrix). 6. Measurement data and specifications: S. cerevisiae arrays were scanned using the HP GeneArray Scanner (Affymetrix) at an emission wavelength of 560 nm, resolution 7.5 uM. Grids were aligned to scans following the library array description. Primary data analyses were carried out using Affymetrix Microarray Suite Ver.5.0 software to obtain signal intensity, fold change value, change p-value and detection p-value. The detailed information of this analysis is available at http://www.affymetrix.com/support/technical/whitepapers/sadd_whitepaper.pdf and http://www.affymetrix.com/support/technical/technotes/statistical_reference_ guide.pdf To discriminate significant signals for binding to DNA (dark grey signals), signals from the ChIP fraction scan were compared to the SUP (supernatant) fraction scan using the 3 following criteria: first, the signal reliability was judged by the detection p-value of each locus (p-value <=0.025); secondly, reliability of binding ratio was judged by change p-value (p- value <=0.025); thirdly, only clusters of at least 3 contiguous loci responding to the 2 previous criteria were selected as significantly enriched locus. The light grey signals represent the statistically not significantly enriched signals. The software to present the result (chr6viewer) is available at http://everythingchromovi.gsc.riken.go.jp. The raw and transformed data files are available at GEO database website and at our web site http://chromosomedynamics.bio.titech.ac.jp. 6. Array Design 1. General array design: in situ synthesized arrays by Affymetrix 2. Availability of arrays: commercially available from Affymetrix 3. Location and ID of each spot on arrays: available at our web site (http://chromosomedynamics.bio.titech.ac.jp) and from Affymetrix on request 4. Probe type: oligonucleotide 5. The arrays used in this study can be purchased from Affymetrix: Chromosome VI S.cerevisiae: rikDACF, P/N# 510636 Chromosome III,IV,V,VIa S.cerevisiae: SC3456a520015F, P/N# 520015 Keywords: other

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Cohesin protects genes against ?H2AX Induced by DNA double-strand breaks.

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Cohesin protects genes against γH2AX Induced by DNA double-strand breaks.

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