Genome-wide maps of double-strand breaks
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE136365 | GEO | 2019/08/27
REPOSITORIES: GEO
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Project description:Cells have developed effective mechanisms, namely homologous recombination (HR) and non-homologous end-joining (NHEJ), to repair DNA double-strand breaks (DSBs), which are considered to be the most deleterious type of damage that can challenge genome integrity. While these pathways coexist to repair DSBs, the mechanisms by which one of these pathways is chosen to repair a particular DSB remain unclear. Here, we show that the chromatin context in which a break occurs participates in this choice and that transcriptionnaly active chromatin channels repair to HR. By using a human cell line expressing a restriction enzyme fused to the ligand binding domain of the oestrogen receptor (AsiSI-ER)2,3, together with a genome wide chromatin immunoprecipitation-sequencing (ChIP-seq) approach, we establish that distinct DSBs induced across the genome are not necessarily repaired by the same pathway. Indeed, we identify an HR-prone subset of DSBs that recruit the HR protein RAD51, undergo resection, and rely on RAD51 for efficient repair. These DSBs are located in actively transcribed genes, and repair at such DSBs can be switched to RAD51-independent repair pathway upon transcriptional inhibition. Moreover, we show that HR is targeted to transcribed loci thanks to the elongation-associated H3K36me3 histone mark. Indeed depletion of HYPB, the main H3K36 tri methyltransferase severally impedes the use of HR at those DSBs. Our study, thereby demonstrates a clear role for chromatin in DSB repair pathway choice in human cells.
2014-03-23 | E-MTAB-1241 | biostudies-arrayexpress
Project description:DNA double-strand breaks (DSBs) initiate meiotic recombination. Past DSB-mapping studies have used rad50S or sae2? mutants, which are defective in break processing, to accumulate DSBs, and report large (= 50 kb) “DSB-hot” regions that are separated by “DSB-cold” domains of similar size. Substantial recombination occurs in some DSB-cold regions, suggesting that DSB patterns are not normal in rad50S or sae2? mutants. We therefore developed novel methods that detect DSBs using ssDNA enrichment and microarray hybridization, and that use background-based normalization to allow cross-comparison between array datasets, to map genome-wide the DSBs that accumulate in processing-capable, repair-defective dmc1î and dmc1î rad51î mutants. DSBs were observed at known hotspots, but also in most previously-identified “DSB-cold” regions, including near centromeres and telomeres. While about 40% of the genome is DSB-cold in rad50S mutants, analysis of meiotic ssDNA from dmc1? shows that most of these regions have significant DSB activity. Thus, DSBs are distributed much more uniformly than was previously believed. Southern-blot assays of DSBs in selected regions in dmc1?, rad50S and wild-type cells confirm these findings. Comparisons of DSB signals in dmc1, dmc1 rad51, and dmc1 spo11 mutant strains identify Dmc1 as the primary strand transfer activity genome-wide, and Spo11-induced lesions as initiating all meiotic recombination. Keywords: DSB mapping, ChIP-chip, single strand DNA , BND cellulose We use two different strategies to map the genome-wide distribution of meiotic DSBs in the yeast Saccharomyces cerevisiae. The first is a chromatin immunoprecipitation (ChIP) based approach that targets the Spo11p protein, which remains covalently attached to DSB ends in the rad50S mutant background. The second approach involves BND cellulose enrichment of the single strand DNA (ssDNA) recombination intermediate formed by end-resection at DSB sites following Spo11p removal. We use dmc1 and dmc1 rad51 mutants that accumulates meiotic single strand DNA intermediates
2007-12-30 | E-GEOD-8981 | biostudies-arrayexpress
Project description:DNA double-strand breaks (DSBs) initiate meiotic recombination. Past DSB-mapping studies have used rad50S or sae2? mutants, which are defective in break processing, to accumulate DSBs, and report large (= 50 kb) “DSB-hot” regions that are separated by “DSB-cold” domains of similar size. Substantial recombination occurs in some DSB-cold regions, suggesting that DSB patterns are not normal in rad50S or sae2? mutants. We therefore developed novel methods that detect DSBs using ssDNA enrichment and microarray hybridization, and that use background-based normalization to allow cross-comparison between array datasets, to map genome-wide the DSBs that accumulate in processing-capable, repair-defective dmc1î and dmc1î rad51î mutants. DSBs were observed at known hotspots, but also in most previously-identified “DSB-cold” regions, including near centromeres and telomeres. While about 40% of the genome is DSB-cold in rad50S mutants, analysis of meiotic ssDNA from dmc1? shows that most of these regions have significant DSB activity. Thus, DSBs are distributed much more uniformly than was previously believed. Southern-blot assays of DSBs in selected regions in dmc1?, rad50S and wild-type cells confirm these findings. Comparisons of DSB signals in dmc1, dmc1 rad51, and dmc1 spo11 mutant strains identify Dmc1 as the primary strand transfer activity genome-wide, and Spo11-induced lesions as initiating all meiotic recombination. Keywords: DSB mapping, ChIP-chip, single strand DNA , BND cellulose
2007-12-31 | GSE8981 | GEO
Project description:Activation-induced cytidine deaminase (AID) is required for initiation of Ig class switch recombination (CSR) and somatic hypermutation (SHM) of antibody genes during immune responses. AID has also been shown to induce chromosomal translocations, mutations, and DNA double-strand breaks (DSBs) involving non-Ig genes in activated B cells. To determine what makes a DNA site a target for AID-induced DSBs, we identify off-target DSBs induced by AID by performing chromatin immunoprecipitation (ChIP) for Nbs1, a protein that binds DSBs, followed by deep sequencing (ChIP-Seq). We detect and characterize hundreds of off-target AID-dependent DSBs. Two types of tandem repeats are highly enriched within the Nbs1-binding sites: long CA repeats, which can form Z-DNA, and tandem pentamers containing the AID target hotspot WGCW. These tandem repeats are not nearly as enriched at AID-independent DSBs, which we also identified. Msh2, a component of the mismatch repair pathway and important for genome stability, increases off-target DSBs, similar to its effect on Ig switch region DSBs, which are required intermediates during CSR. Most of the off-target DSBs are two-ended, consistent with generation during G1 phase, similar to DSBs in Ig switch regions. However, a minority are one-ended, presumably due to conversion of single-strand breaks to DSBs during replication. One-ended DSBs are repaired by processes involving homologous recombination, including break-induced replication repair, which can lead to genome instability. Off-target DSBs, especially those present during S phase, can lead to chromosomal translocations, deletions and gene amplifications, resulting in the high frequency of B cell lymphomas derived from cells that express or have expressed AID.
2015-07-16 | GSE66424 | GEO
Project description:The Spo11-generated double-strand breaks (DSBs) that initiate meiotic recombination are non-randomly distributed across the genome. Here, we use Spo11-oligonucleotide complexes to map the distribution of meiotic DSBs in a spo11 mutant strain of Saccharomyces cerevisiae.
2020-05-12 | GSE150314 | GEO
Project description:The pleiotropic CCCTC-binding factor (CTCF) plays a role in homologous recombination (HR) repair of DNA double-strand breaks (DSBs). However, the precise mechanistic role of CTCF in HR remains largely unclear. Here, we show that CTCF engages in DNA end resection, which is the initial, crucial step in HR, through its interactions with MRE11 and CtIP. Depletion of CTCF profoundly impairs HR and attenuates CtIP recruitment at DSBs. CTCF physically interacts with MRE11 and CtIP and promotes CtIP recruitment to sites of DNA damage. Subsequently, CTCF facilitates DNA end resection to allow HR, in conjunction with MRE11-CtIP. Notably, the zinc finger domain of CTCF binds to both MRE11 and CtIP and enables proficient CtIP recruitment, DNA end resection, and HR. The N-terminus of CTCF is able to bind to only MRE11 and its C-terminus is incapable of binding to MRE11 and CtIP, thereby resulting in compromised CtIP recruitment, DSB resection, and HR. Overall, this suggests an important function of CTCF in DNA end resection through the recruitment of CtIP at DSBs. Collectively, our findings identify a critical role of CTCF at the first control point in selecting the HR repair pathway
2019-11-12 | PXD014441 | Pride
Project description:DNA Double Strands Breaks (DSBs) are highly detrimental since they can lead to mutations and chromosomes rearrangements (amplification, deletion, translocation and chromosome loss). Here, we used in a standardized system, where multiples DSBs are induced at defined positions across the human genome (U2OS-DIvA cells), to describe the distribution of eighteen histone modifications before and after damage using ChIP-Seq. This provides a comprehensive picture of the chromatin landscape induced at DSBs.
2018-09-27 | E-MTAB-5817 | biostudies-arrayexpress
Project description:Homologous recombination (HR) is crucial for genetic exchange, accurate repair of DNA double-strand breaks and pivotal for genome integrity. HR uses homologous sequences for repair, but how homology search, the exploration of the genome for homologous DNA sequences, is conducted in the nucleus remains poorly understood. Here, we use time-resolved chromatin immunoprecipitations of repair proteins to monitor homology search in vivo. We found that homology search proceeds by a probing mechanism, which commences around the break and samples preferentially on the broken chromosome. However, elements thought to instruct chromosome loops mediate homology search shortcuts, and centromeres, which cluster within the nucleus, may facilitate homology search on other chromosomes. Our study thus revealed crucial parameters for homology search in vivo and emphasizes the importance of linear distance, chromosome architecture and proximity for recombination efficiency. 2 new custom ChIP-chip platforms used; both Nimblegen; differ in oligo density: (platform 1: 2006-07-18_Scerevisiae_ChIP_Stefan Jentsch MPI Biochemistry S.cerevisiae 385K Tiling Array Version 1) ( platform 2: 100304_Scer2_MS_Chip_Stefan Jentsch MPI Biochemistry S.cerevisiae 135K Tiling Array Version 2) ChIP-chip profiling of DSB repair factors (Rad51, Rad52, RPA, gamma-H2A) upon single inducible DSBs in S.cerevisiae
2013-03-21 | E-GEOD-44844 | biostudies-arrayexpress
Project description:The Spo11-generated double-strand breaks (DSBs) that initiate meiotic recombination are non-randomly distributed across the genome. Here, we use Spo11-oligonucleotide complexes, a byproduct of DSB formation, to map the distribution of meiotic DSBs in pch2 and sir2 mutant strains of Saccharomyces cerevisiae.
2018-11-25 | GSE122882 | GEO
Project description:DNA Double-Strand Breaks (DSBs) are highly detrimental since they can lead to mutations and chromosomes rearrangements (amplification, deletion, translocation and chromosome loss). ChIP-chip of P-SMC3 (S1083) and P-SMC1 (S966) were used to show the recruitment of these marks on DNA repair foci. ChIP-chip of gammaH2AX upon CRISPR induction at different positions within a single TAD was also performed.
2021-01-29 | E-MTAB-8793 | biostudies-arrayexpress