Project description:ChIP-seq profile of Rec8 binding sites arrested in metaphase I by depletion of the APC/C activator CDC20. The aim of this experiment is to identify Rec8 binding sites in metaphase I.
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:ChIP-seq profile of Spo13 binding sites arrested in prophase I by deletion of the meiotic transcription factor NDT80. Previous ChIP-ChIP data had indicated that Spo13 binding correlates with cohesin binding sites. Therefore, in addition to wild type cells, we also investigated cells deficient of the meiosis-specific cohesin subunit Rec8 to identify cohesin-dependent binding sites of Spo13.
Project description:Segregation of homologous maternal and paternal centromeres to opposite poles during meiosis I depends on post-replicative crossing over between homologous non-sister chromatids, which creates chiasmata and therefore bivalent chromosomes. Destruction of sister chromatid cohesion along chromosome arms due to proteolytic cleavage of cohesin's Rec8 subunit by separase resolves chiasmata and thereby triggers the first meiotic division. This produces univalent chromosomes, the chromatids of which are held together by centromeric cohesin that has been protected from separase by shugoshin (Sgo1/MEI-S332) proteins. Here we show in both fission and budding yeast that Sgo1 recruits to centromeres a specific form of protein phosphatase 2A (PP2A). Its inactivation causes loss of centromeric cohesin at anaphase I and random segregation of sister centromeres at the second meiotic division. Artificial recruitment of PP2A to chromosome arms prevents Rec8 phosphorylation and hinders resolution of chiasmata. Our data are consistent with the notion that efficient cleavage of Rec8 requires phosphorylation of cohesin and that this is blocked by PP2A at meiosis I centromeres. Keywords: ChIP-chip, Mitosis, Meiosis, Cell cycle, Saccharomyces cerevisiae, Chromosome VI tiling array, Sgo1, Pp2A, Cse4, Ndc10, Rts1, Rec8
Project description:During meiotic prophase, cohesin-dependent axial structures are formed in the synaptonemal complex (SC). However, functional correlation between these structure formation and cohesion remains elusive. Here we examined formation of the cohesin-dependent axial structure in fission yeast, which forms atypical SCs composed of linear elements (LinEs) resembling the lateral elements of SC but lacking the central elements, and found that Rec8 cohesin is crucial for the formation of the loop-axis structure within the atypical SC. Furthermore, the Rec8-mediated loop-axis structure is formed in the absence of LinEs, and provides a structural platform for aligning homologous chromosomes. We also succeeded to identify a rec8 mutant that lost the ability of assembling the loop-axis structure without losing cohesion. Remarkably, this mutant showed defects in LinE assembly, resulting in great reduction of meiotic recombination. Collectively, our results demonstrate an essential role of the Rec8-dependent loop-axis structure in LinE assembly, facilitating meiotic recombination.
Project description:During mouse meiosis, DNA double-strand breaks (DSBs) are initiated by SPO11 at recombination hotspots (HSs), activated by PRDM9. Although activated HSs are marked by H3K4me3 and H3K36me3 histone modifications at open chromatin, most of the DSB-initiating and repair proteins are associated with the chromosome axis. This study addresses the mechanistic importance of the axis-associated cohesin proteins in DSB formation. We demonstrate that interactions between PRDM9 and the meiotic axis proteins STAG3 and REC8 are essential for efficient DSB formation. The absence of STAG3 or REC8 leads to inefficient meiotic DSB formation at HSs. STAG3 is critical for DSB formation, even at PRDM9-independent DSB-sites. Also, STAG3 and REC8 facilitate recruitment of the DSB-promoting proteins HORMAD1, IHO1 and MEI4 required for SPO11 activity. Together, these results support an evolutionarily conserved model in which axis-associated cohesin complexes recruit recombination-initiating proteins to DSB sites to promote meiotic recombination initiation.
Project description:ChIP-seq profile of Sgo1 binding sites arrested in metaphase I by deletion of the APC/C activator CDC20. The aim of this experiment is to identify whether Sgo1 binding differs in wild type cells and cells deficient of the meiosis I-specific protein Spo13, which is required for retention of pericentromeric cohesin after metaphase I.
Project description:Calibrated ChIP-seq for meiotic-specific cohesin (Rec8) and mitotic-specific cohesin (Scc1) in budding yeast cells arrested in metaphase of mitosis
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.