Genomic features shaping the landscape of meiotic double-strand break hotspots in maize [ChIP-Seq]
Ontology highlight
ABSTRACT:
ORGANISM(S): Zea mays
PROVIDER: GSE55701 | GEO | 2016/07/08
SECONDARY ACCESSION(S): PRJNA240574
REPOSITORIES: GEO
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Project description:Repair of DNA double-strand break (DSB) is critical for the maintenance of genome integrity. We have previously shown that a class of DSB-induced small RNAs (diRNAs) facilitates homologous recombination (HR)-mediated DSB repair in Arabidopsis thaliana. Here we show that INVOLVED IN DE NOVO 2 (IDN2), a double-stranded RNA (dsRNA) binding protein involved in small RNA-directed DNA methylation, is required for DSB repair in Arabidopsis. We find that IDN2 interacts with the heterotrimeric replication protein A (RPA) complex. Depletion of IDN2 or the diRNA-binding ARGONAUTE 2 (AGO2) leads to increased accumulation of RPA at DSB sites and mislocalization of the recombination factor RAD51. These findings support a model in which IDN2 interacts with RPA and facilitates the release of RPA from ssDNA tails and subsequent recruitment of RAD51 at DSB sites to promote DSB repair.
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Project description:Meiotic recombination, crucial for proper chromosome segregation and genome evolution, is initiated by programmed DNA double-strand breaks (DSBs) in budding and fission yeasts and likely all sexually reproducing species. In fission yeast, DSBs occur up to several hundred times more frequently at special sites, called hotspots, than in other regions of the genome. What distinguishes hotspots from cold regions is a major unsolved problem, although transcription factors determine some hotspots. We report here the discovery that three coiled-coil proteins -- Rec25, Rec27, and Mug20 -- bind essentially all hotspots with unprecedented, high specificity even without DSB formation. These small proteins are components of linear elements, are related to synaptonemal complex proteins, and are essential for nearly all DSBs at most hotspots. Our results indicate that these hotspot determinants activate or stabilize the DSB-forming protein Rec12 (Spo11 homolog) rather than promote its binding to hotspots. We propose here a new paradigm for hotspot determination and crossover control by linear element proteins.
2012-12-26 | GSE43121 | GEO
Project description:Meiotic recombination, crucial for proper chromosome segregation and genome evolution, is initiated by programmed DNA double-strand breaks (DSBs) in budding and fission yeasts and likely all sexually reproducing species. In fission yeast, DSBs occur up to several hundred times more frequently at special sites, called hotspots, than in other regions of the genome. What distinguishes hotspots from cold regions is a major unsolved problem, although transcription factors determine some hotspots. We report here the discovery that three coiled-coil proteins -- Rec25, Rec27, and Mug20 -- bind essentially all hotspots with unprecedented, high specificity even without DSB formation. These small proteins are components of linear elements, are related to synaptonemal complex proteins, and are essential for nearly all DSBs at most hotspots. Our results indicate that these hotspot determinants activate or stabilize the DSB-forming protein Rec12 (Spo11 homolog) rather than promote its binding to hotspots. We propose here a new paradigm for hotspot determination and crossover control by linear element proteins.
2012-12-26 | GSE43118 | GEO
Project description:Every chromosome requires at least one crossover to be faithfully segregated during meiosis. At least two levels of regulation govern crossover distribution; where the initiating DNA double-strand breaks (DSBs) occur and whether those DSBs are repaired as crossovers. We mapped meiotic DSBs in budding yeast by identifying sites of DSB-associated single-stranded DNA (ssDNA) accumulation. These analyses revealed substantial DSB activity in regions close to centromeres, where crossover formation is largely absent. Our data suggest that centromeric suppression of recombination occurs at the level of break repair rather than DSB formation. Additionally, we found an enrichment of DSBs within a ~100-kb region near the ends of all chromosomes. Introduction of new telomeres was sufficient to induce large ectopic regions of increased DSB formation, revealing a remarkable long-range effect of telomeres on DSB formation. The concentration of DSBs close to chromosome ends increases the relative DSB density on small chromosomes, providing an interference-independent mechanism to ensure that all chromosomes receive at least one crossover per homolog pair. Together, our results indicate that selective DSB repair accounts for crossover suppression near centromeres, and suggest a simple telomere-guided mechanism to ensure sufficient DSB activity on all chromosomes. Keywords: ssDNA analysis, comparative genomic hybridization, ChIP-chip
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Project description:SPO11 generates hundreds of DNA double-strand breaks (DSBs) to initiate meiotic recombination. Heritability and genome stability are shaped by the nonrandom distribution of DSBs, but mechanisms molding this landscape remain poorly understood. Here we exploit genome-wide maps of mouse DSBs at unprecedented nucleotide resolution to uncover previously invisible spatial features of recombination. At fine scale, we reveal a stereotyped hotspot structure––DSBs occur within narrow zones between methylated nucleosomes––and identify relationships between SPO11, chromatin, and the histone methyltransferase PRDM9. At large scale, DSB formation is suppressed on non-homologous portions of the sex chromosomes via the DSB-responsive kinase ATM, which also shapes the autosomal DSB landscape at multiple size scales. We also provide the first genome-wide analysis of exonucleolytic DSB resection lengths and elucidate spatial relationships between DSBs and recombination products. Our results paint a comprehensive picture of features that govern successive steps in mammalian meiotic recombination.
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Project description:In most mammals, including mice and humans, meiotic recombination is determined by the meiosis specific histone methytransferase PRDM9, which binds to specific DNA sequences and trimethylates histone 3 at lysine-4 and lysine-36 at the adjacent nucleosomes. These actions ensure successful DNA double strand break formation and repair that occur on the proteinaceous structure forming the chromosome axis. The process of hotspot association with the axis after their activation by PRDM9 is poorly understood. Previously, we and others have identified CXXC1, an ortholog of S. cerevisiae Spp1 in mammals, as a PRDM9 interactor. In yeast, Spp1 is a histone methyl reader that links H3K4me3 sites with the recombination machinery, promoting DSB formation. Here, we investigated whether CXXC1 has a similar function in mouse meiosis. We created two Cxxc1 conditional knockout mouse to deplete CXXC1 generally in germ cells, and before the onset of meiosis. Surprisingly, male knockout mice were fertile, and the loss of CXXC1 in spermatocytes had no effect on hotspot trimethylation, double-strand break formation or repair. Our results demonstrate that CXXC1 is not an essential link between PRDM9-activated recombination hotspot sites and DSB machinery and that the hotspot recognition pathway in mouse is independent of CXXC1.
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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
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