Project description:Spo11-mediated DNA double strand breaks (DSBs) that initiate meiotic recombination are temporally and spatially controlled. The meiotic cohesin Rec8 has been implicated in regulating DSB formation, but little is known about the features of their interplay. To shed light on this point, we investigated the genome-wide localization of Spo11 in budding yeast during early meiosis by chromatin immunoprecipitation using high-density tiling arrays. We found that Spo11 is dynamically localized to meiotic chromosomes. Spo11 initially accumulated around centromeres and thereafter localized to arm regions as premeiotic S-phase proceeded. During this stage, a substantial proportion of Spo11 bound to Rec8 binding sites. Eventually, some of Spo11 further bound to both DSB and Rec8 sites. We also showed that such a change in a distribution of Spo11 is affected by hydroxyurea (HU) treatment. Interestingly, deletion of REC8 influences the localization of Spo11 to centromeres and in some of the intervals of the chromosomal arms. Thereby we observed a lack of DSB formation in a region-specific manner. These observations suggest that Rec8 would prearrange the distribution of Spo11 along chromosomes and will provide clues to understanding temporal and spatial regulation of DSB formation. Keywords: ChIP-chip
Project description:Meiotic chromosome architecture called M-bM-^@M-^\axis-loop structuresM-bM-^@M-^] and histone modifications have been demonstrated to regulate the Spo11-dependent formation of DNA double-strand breaks (DSBs) that trigger meiotic recombination. Using genome-wide chromatin immunoprecipitation (ChIP) analyses followed by deep sequencing, we compared the genome-wide distribution of the axis protein Rec8 (the kleisin subunit of meiotic cohesin) with that of oligomeric DNA covalently bound to Spo11, indicative of DSB sites. The frequency of DSB sites is overall constant between Rec8 binding sites. However, DSB cold spots are observed in regions spanning M-BM-10.8 kb around Rec8 binding sites. The axis-associated cold spots are not due to exclusion of Spo11 localization from the axis, since ChIP experiments revealed that substantial Spo11 persists at Rec8 binding sites during DSB formation. Spo11 fused with Gal4 DNA binding domain (Gal4BD-Spo11) tethered in close proximity (M-bM-^IM-$0.8 kb) to Rec8 binding sites hardly forms meiotic DSBs, in contrast with other regions. In addition, H3K4 tri-methylation (H3K4me3) remarkably decreases at Rec8 binding sites. These results suggest that reduced histone H3K4me3 in combination with inactivation of Spo11 activity on the axis discourages DSB hot spot formation. ChIP-seq analyses of Rec8, Spo11, and Gal4BD-Spo11 on budding yeast meiotic chromosomes M-bM-^@M-" Distribution of Rec8 in wt and Gal4BD-Spo11-expressing cells at 4h after meiotic induction M-bM-^@M-" Distribution of Spo11 at 3h, 4h, and 5h after meiotic induction M-bM-^@M-" Distribution of Gal4BD-Spo11 at 0h after meiotic induction
Project description:Spo11-mediated DNA double strand breaks (DSBs) that initiate meiotic recombination are temporally and spatially controlled. The meiotic cohesin Rec8 has been implicated in regulating DSB formation, but little is known about the features of their interplay. To shed light on this point, we investigated the genome-wide localization of Spo11 in budding yeast during early meiosis by chromatin immunoprecipitation using high-density tiling arrays. We found that Spo11 is dynamically localized to meiotic chromosomes. Spo11 initially accumulated around centromeres and thereafter localized to arm regions as premeiotic S-phase proceeded. During this stage, a substantial proportion of Spo11 bound to Rec8 binding sites. Eventually, some of Spo11 further bound to both DSB and Rec8 sites. We also showed that such a change in a distribution of Spo11 is affected by hydroxyurea (HU) treatment. Interestingly, deletion of REC8 influences the localization of Spo11 to centromeres and in some of the intervals of the chromosomal arms. Thereby we observed a lack of DSB formation in a region-specific manner. These observations suggest that Rec8 would prearrange the distribution of Spo11 along chromosomes and will provide clues to understanding temporal and spatial regulation of DSB formation. Keywords: ChIP-chip â?¢ The goal of the experiment Genome-wide localization of Spo11, Mre11, Rec8, and DSB sites on meiotic chromosomes in Saccharomyces cerevisiae â?¢ Keywords Meiosis, Meiotic homologous recombination, Premeiotic DNA replication, cohesin, Saccharomyces cerevisiae, Genome tilling array (chromosome III, IV, V, VI), Spo11, Mre11, Rec8, DSB (Double strand break) â?¢ Experimental factor Distribution of Spo11, Mre11, and Rec8 in wild type in early meiosis (1.5 hrs, 2 hrs, 3 hrs, 4 hrs, and 5 hrs in sporulation medium) Distribution of Spo11 in rec8delta cells in early meiosis (1.5 hrs, 2 hrs, 3 hrs, 4 hrs, and 5 hrs in sporulation medium) Distribution of Spo11 in wild type in the presence of HU (2hrs and 4 hrs in sporulation medium containing HU) Distribution of DSB sites in rad50S mutant cells at 7 hrs in sporulation medium Distribution of DSB sites in rec8delta rad50S mutant cells at 7 hrs in sporulation medium â?¢ Experimental design ChIP analyses: SK1 background cells expressing FLAG tagged protein were used for the ChIP using anti-FLAG M2 antibody. ChIP-chip analyses: In all cases, hybridization data for ChIP fraction was compared with WCE (whole cell extract) fraction. Saccharomyces cerevisiae affymetrix genome tiling array (SC3456a520015F for chromosome III, IV, V, VI and rikDACF for chromosome VI) were used. Mapping of DSB sites: DSB rich fraction was concentrated by ChIP of Spo11-FLAG in rad50S mutant without crosslinking. In the mutant, DSBs ramain unrepaired with covalently attached Spo11.Meiotic cells (at 7 hours in sporulation medium) were used for the analyses. â?¢ Quality control steps taken Confirmation of several loci by quantitative real time PCR. Southern blotting of several DSB sites.
Project description:Meiotic chromosome architecture called M-bM-^@M-^\axis-loop structuresM-bM-^@M-^] and histone modifications have been demonstrated to regulate the Spo11-dependent formation of DNA double-strand breaks (DSBs) that trigger meiotic recombination. Using genome-wide chromatin immunoprecipitation (ChIP) analyses followed by deep sequencing, we compared the genome-wide distribution of the axis protein Rec8 (the kleisin subunit of meiotic cohesin) with that of oligomeric DNA covalently bound to Spo11, indicative of DSB sites. The frequency of DSB sites is overall constant between Rec8 binding sites. However, DSB cold spots are observed in regions spanning M-BM-10.8 kb around Rec8 binding sites. The axis-associated cold spots are not due to exclusion of Spo11 localization from the axis, since ChIP experiments revealed that substantial Spo11 persists at Rec8 binding sites during DSB formation. Spo11 fused with Gal4 DNA binding domain (Gal4BD-Spo11) tethered in close proximity (M-bM-^IM-$0.8 kb) to Rec8 binding sites hardly forms meiotic DSBs, in contrast with other regions. In addition, H3K4 tri-methylation (H3K4me3) remarkably decreases at Rec8 binding sites. These results suggest that reduced histone H3K4me3 in combination with inactivation of Spo11 activity on the axis discourages DSB hot spot formation. ChIP-chip analysis of Rec8 on fission yeast meiotic chromosomes
Project description:Meiotic recombination starts with the formation of DNA double-strand breaks (DSBs) made by Spo11. In Saccharomyces cerevisiae, the nonrandom distribution of meiotic DSBs along the genome can be attributed to the combined influence of multiple factors on Spo11 cleavage. One factor is higher-order chromatin structure, particularly the loop-axis organization of meiotic chromosomes. Axial element proteins Red1 and Hop1 provide the basis for meiotic loop-axis organization and are implicated in diverse aspects of meiotic recombination. Mek1 is a meiotic-specific kinase associated with Red1 and Hop1. Red1, Hop1, and Mek1 are required for normal DSB levels, but their effects on the DSB distribution has not been examined, and exactly how these proteins influence DSB levels and distribution is unknown. Here, we examined the contributions of Red1, Hop1, and Mek1 to the DSB distribution by deep sequencing and mapping Spo11-associated oligonucleotides from red1, hop1, and mek1 mutant strains, thereby generating genome-wide meiotic DSB maps.
Project description:The mitotic cohesin complex necessary for sister chromatid cohesion and chromatin loop formation shows local and global association to chromosomes in response to DNA double-strand breaks (DSBs). Here, by genome-wide binding analysis of the meiotic cohesin with Rec8 as a kleisin, we found that Rec8 shows dynamic localization from middle to late meiotic prophase I with cleavage-independent global dissociation along chromosomes, driven by meiotic DSB formation. Each Rec8 binding site on the chromosome axis follows distinct dynamics with dissociation and association. Centromeres also showed reduced Rec8 binding in late prophase I relative to mid-prophase I, implying chromosome remodeling of the regions. Rec8 dissociation profile per chromosome is largely correlated with meiotic DSB density. Indeed, the spo11 mutant deficient in meiotic DSB formation did not show the cleavage-independent dissociation of Rec8 in late meiotic prophase I. These suggest the presence of a regulatory pathway for global Rec8-cohesin dynamics in response to meiotic DSBs.
Project description:Meiotic chromosome architecture called “axis-loop structures” and histone modifications have been demonstrated to regulate the Spo11-dependent formation of DNA double-strand breaks (DSBs) that trigger meiotic recombination. Using genome-wide chromatin immunoprecipitation (ChIP) analyses followed by deep sequencing, we compared the genome-wide distribution of the axis protein Rec8 (the kleisin subunit of meiotic cohesin) with that of oligomeric DNA covalently bound to Spo11, indicative of DSB sites. The frequency of DSB sites is overall constant between Rec8 binding sites. However, DSB cold spots are observed in regions spanning ±0.8 kb around Rec8 binding sites. The axis-associated cold spots are not due to exclusion of Spo11 localization from the axis, since ChIP experiments revealed that substantial Spo11 persists at Rec8 binding sites during DSB formation. Spo11 fused with Gal4 DNA binding domain (Gal4BD-Spo11) tethered in close proximity (≤0.8 kb) to Rec8 binding sites hardly forms meiotic DSBs, in contrast with other regions. In addition, H3K4 tri-methylation (H3K4me3) remarkably decreases at Rec8 binding sites. These results suggest that reduced histone H3K4me3 in combination with inactivation of Spo11 activity on the axis discourages DSB hot spot formation.
Project description:Meiotic chromosome architecture called “axis-loop structures” and histone modifications have been demonstrated to regulate the Spo11-dependent formation of DNA double-strand breaks (DSBs) that trigger meiotic recombination. Using genome-wide chromatin immunoprecipitation (ChIP) analyses followed by deep sequencing, we compared the genome-wide distribution of the axis protein Rec8 (the kleisin subunit of meiotic cohesin) with that of oligomeric DNA covalently bound to Spo11, indicative of DSB sites. The frequency of DSB sites is overall constant between Rec8 binding sites. However, DSB cold spots are observed in regions spanning ±0.8 kb around Rec8 binding sites. The axis-associated cold spots are not due to exclusion of Spo11 localization from the axis, since ChIP experiments revealed that substantial Spo11 persists at Rec8 binding sites during DSB formation. Spo11 fused with Gal4 DNA binding domain (Gal4BD-Spo11) tethered in close proximity (≤0.8 kb) to Rec8 binding sites hardly forms meiotic DSBs, in contrast with other regions. In addition, H3K4 tri-methylation (H3K4me3) remarkably decreases at Rec8 binding sites. These results suggest that reduced histone H3K4me3 in combination with inactivation of Spo11 activity on the axis discourages DSB hot spot formation.
Project description:The meiotic cohesin Rec8 is required for the stepwise segregation of chromosomes during the two rounds of meiotic division. By directly measuring chromosome compaction in living cells of the fission yeast Schizosaccharomyces pombe, we found an additional role for the meiotic cohesin in the compaction of chromosomes during meiotic prophase. In the absence of Rec8, chromosomes were decompacted relative to those of wild-type cells. Conversely, loss of the cohesin-associated protein Pds5 resulted in hyper-compaction. While this hyper-compaction requires Rec8, binding of Rec8 to chromatin was reduced in the absence of Pds5, indicating that Pds5 promotes chromosome association of Rec8. To explain these observations, we propose that meiotic prophase chromosomes are organized as chromatin loops emanating from a Rec8-containing axis; the absence of Rec8 disrupts the axis, resulting in disorganized chromosomes, whereas reduced Rec8 loading results in a longitudinally compacted axis with fewer attachment points and longer chromatin loops. Keywords: ChIP-chip analysis
Project description:Homologous recombination is the key process that generates genetic diversity and drives evolution. SPO11 protein triggers recombination by introducing DNA double stranded breaks at discreet areas of the genome called recombination hotspots. The hotspot locations are largely determined by the DNA binding specificity of the PRDM9 protein in human, mice and most other mammals. In budding yeast Saccharomyces cerevisae, which lacks a Prdm9 gene, meiotic breaks are formed opportunistically in the regions of accessible chromatin, primarily at gene promoters. The genome-wide distribution of hotspots in this organism can be altered by tethering Spo11 protein to Gal4 recognition sequences in the strain expressing Spo11 attached to the DNA binding domain of the Gal4 transcription factor. To establish whether similar re-targeting of meiotic breaks can be achieved in PRDM9-containing organisms we have generated a Gal4BD-Spo11 mouse that expresses SPO11 protein joined to the DNA binding domain of yeast Gal4. We have mapped the genome-wide distribution of the recombination initiation sites in the Gal4BD-Spo11 mice. More than two hundred of the hotspots in these mice were novel and were likely defined by Gal4BD, as the Gal4 consensus motif was clustered around the centers in these hotspots. Surprisingly, meiotic DNA breaks in the Gal4BD-Spo11 mice were significantly depleted near the ends of chromosomes. The effect is particularly striking at the pseudoautosomal region of the X and Y chromosomes – normally the hottest region in the genome. Our data suggest that specific, yet-unidentified factors influence the initiation of meiotic recombination at subtelomeric chromosomal regions. Detection of meiotic double strand breaks in mice with a hypomorphic Spo11 allele.