Pcs1 and Mde4 are inner centromere proteins required to prevent merotelic kinetochore orientation
Ontology highlight
ABSTRACT:
ORGANISM(S): Schizosaccharomyces pombe
SUBMITTER: Kim Nasmyth
PROVIDER: E-GEOD-5257 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Publications
The kinetochore proteins Pcs1 and Mde4 and heterochromatin are required to prevent merotelic orientation.
Gregan Juraj J Riedel Christian G CG Pidoux Alison L AL Katou Yuki Y Rumpf Cornelia C Schleiffer Alexander A Kearsey Stephen E SE Shirahige Katsuhiko K Allshire Robin C RC Nasmyth Kim K
Current biology : CB 20070701 14
<h4>Background</h4>Accurate chromosome segregation depends on the establishment of correct-amphitelic-kinetochore orientation. Merotelic kinetochore orientation is an error that occurs when a single kinetochore attaches to microtubules emanating from opposite spindle poles, a condition that hinders segregation of the kinetochore to a spindle pole in anaphase. To avoid chromosome missegregation resulting from merotelic kinetochore orientation, cells have developed mechanisms to prevent or correct ...[more]
Similar Datasets
Project description:The segregation of maternal centromeres away from the paternal ones during the first division of meiosis depends on the attachment of sister kinetochores to microtubules emanating from the same spindle pole. In budding yeast monopolar attachment requires the recruitment to kinetochores of a protein complex called monopolin. The biochemical function of monopolin was unknown. Here, we have identified the casein kinase I Hrr25 as a hitherto unknown subunit of monopolin. Hrr25 differs from other monopolin components by its enzymatic activity and strong evolutionary conservation. We demonstrate that Hrr25âs kinase activity and its interaction with monopolin are both required for monopolar attachment. Accordingly, Hrr25 is associated with centromeres in meiosis I. Our results revealed a surprising new role for casein kinases and provide a hypothesis for the mechanism of monopolar attachment during meiosis I in sexually reproducing organisms: casein kinase I-dependent phosphorylation of kinetochore proteins. Keywords: ChIP-chip, Meiosis, Cell cycle, Saccharomyces cerevisiae, Chromosome VI tiling array, Hrr25, Mam1 ⢠Experimental factors Distribution of the Hrr25 and Mam1 at Meiosis I. Distribution of Hrr25 in Mam1 deletion mutant (S.cerevisiae). All experiments were performed in cells with the same genetic background (Saccharomyces cerevisiae SK1). ⢠Experimental design ChIP analysis: In all cases, hybridization data for ChIP fraction was compared with that of SUP (supernatant) fraction. Cerevisiae chromosome VI array was used. ⢠Quality control steps taken Confirmation using different subunits of the same complex. Confirmation of protein distribution using deletion mutant strain. Checking of the ChIP fraction by Western blotting. Mock hybridisation of samples immunoprecipitated from cells containing no tag recognized by antibody used. Swapping SUP fraction. Q-PCR. Samples used, extract preparation and labelling: ⢠The origin of each biological sample Saccharomyces cerevisiae (SK1). ⢠Manipulation of biological samples and protocols used Chromatin immunoprecipitation (ChIP) and hybridization to Affimetrix high-density oligonucleotide arrays of S. cerevisiae chromosome VI were performed essentially as previously described (Katou et al., 2003, nature) (Lengronne et al., 2004, nature). ⢠Technical protocols for preparing the hybridization extract The chromatin-immunprecipates were eluted and incubated over night at 65ºC 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 95ºC. DNA fragments were end-labeled by addition of 25 U of Terminal Transferase and 1 nmol Biotin-N6ddATP (NEN) for 1 hour at 37ºC as previously described by Winzeler et al. (Science. 281, 1194-1197, 1998). The entire sample was used for hybridization. ⢠Hybridization procedures and parameters: Hybridization, blocking and washing were carried out as previously described (http://everythingchromosomevi.gsc.riken.go.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 3âbiotin labelled control oligonucleotide (oligo B2, Affymetrix). Samples were denatured at 100ºC for 10 minutes, and then put on ice before being hybridized for 16 hours at 42ºC in a hybridization oven (GeneChip Hybridization Oven 640, Affymetrix). Washing and scanning protocol provided by Affymetrix was performed automatically on a fluidics station (GeneChip fluidics station 450, Affymetrix). ⢠Measurement data and specifications: Arrays were scanned using the Genechip Scanner3000 7G following the library array description. All the raw data files can be downloaded from GEO database. The primary analysis of tiling chip data was performed following exactly the statistical algorithm used for Affymetrix GeneChip Operating Software (GCOS). The detailed information for the algorithm used can be downloaded from the Affymetrix web site at http://www.affymetrix.com/support/technical/technotes/statistical_reference_guide.pdf. The analysis is available on request. For the ChrVI array, one unit for analysis (locus) was set to 300bp. Fold change value, change p-value, and detection p-value for each locus were obtained by primary analysis. For the discrimination of positive and negative signals for the binding, we used three criteria as follows. First, the reliability of the signal strength was judged by detection p-value of each locus (p-valueâ¤0.025). Secondly, reliability of binding ratio was judged by change p-value (p-valueâ¤0.025). Thirdly, clusters consisting of at least 900bp contiguous loci that satisfied the above two criteria were selected, because it is known that a single site of protein-DNA interaction resulted in immuno-precipitation of DNA fragments that hybridized not only to the locus of the actual binding site but also to its neighbors. ⢠Array Design: General array design: in situ synthesized arrays by Affymetrix Availability of arrays: commercially available from Affymetrix Location and ID of each spot on arrays: available from Affymetrix on request Probe type: oligonucleotide The arrays used in this study can be purchased from Affymetrix: Chromosome VI S.cerevisiae: rikDACFC6, P/N# 510636
2010-06-10 | E-GEOD-4792 | biostudies-arrayexpress
Project description:Chromosome segregation depends on proper attachment of sister kinetochores to microtubules. Merotelic kinetochore orientation is an error which occurs when a single kinetochore is attached to microtubules emanating form opposite poles. Mechanisms preventing or correcting the merotelic attachment must operate to avoid chromosome missegregation. Pcs1 has been implicated in preventing merotelic attachment in mitosis and meiosis II. We describe here the identification of Mde4 protein which forms a complex with the Pcs1. Both Mde4 and Pcs1 localize to the central core of the centromere. Similarly to the pcs1 mutant, in the absence of mde4 lagging chromosomes are frequently observed during mitosis and meiosis II . We provide the first evidence that the lagging chromosomes in pcs1 and mde4 mutants are due to merotelic kinetochore orientation. Keywords: ChIP-chip analysis
2007-06-18 | GSE5257 | GEO
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 ChIP analysis of Rec8: In all cases, hybridization data for ChIP fraction was compared with that of SUP (supernatant) fraction. Pombe chromosome II, III array was used.
2010-07-01 | E-GEOD-5284 | biostudies-arrayexpress
Project description:Sister chromatid cohesion is mediated by cohesin but the process of cohesion establishment during S phase is still enigmatic. Recent data indicate that in mammalian cells, cohesin binding to chromatin is dynamic in G1 but becomes stabilized during S phase. Whether the regulation of chromosomal cohesin turn-over is integral to the process of cohesion establishment is unknown. Here, we provide evidence that fission yeast cohesin also displays dynamic behaviour. Cohesin association with G1 chromosomes requires continued activity of the cohesin loader Mis4/Ssl3, implying that repeated loading cycles maintain cohesin binding. Cohesin retention on G1 chromosomes was improved by deletion of wpl, the fission yeast ortholog of mammalian WAPL, suggestive of a conserved mechanism that controls cohesin stability on chromosomes. wpl is non-essential, indicating that a change in wpl-dependent cohesin turnover is not integral to the mechanism of cohesion establishment. Instead we find that cohesin instability is down-regulated during S phase in a reaction independent of DNA replication. Hence, cohesin stabilization might be a pre-requisite for cohesion establishment rather than its consequence. Keywords: ChIP-chip Experiments in budding and fission yeast have shown that the cohesin loading factors are dispensable for viability in G2, when cohesion has been established (Bernard et al., 2006; Ciosk et al., 2000). In fission yeast, inactivation of the loading machinery at that time no longer affects cohesin binding to chromosomes (Bernard et al., 2006). In mammalian cells, about one-third of nuclear cohesin becomes stably bound to chromatin in G2 (Gerlich et al., 2006). Since the binding of cohesin to chromosomes appears labile in G1, but stabilized in G2, we asked how cohesin becomes stable during the intervening S phase. Spreads showed that Rad21 was only slightly decreased in HU arrested cells after inactivation of the cohesin loading factors Mis4 or Ssl3. In this series we analyzed whether cohesin association was equally stabilised at all its association sites along chromosome arms. Rad21 binding was therefore analyzed on a chromosome-wide scale by ChIP followed by hybridization to an oligonucleotide tiling array covering chromosomes 2 and 3. We compared the Rad21 binding pattern in HU arrested wild-type versus ssl3-29 cells after the shift to the restrictive temperature. Four 50 kb regions from chromosome 2 are shown in Figure 5, and the complete chromosome 2 in Supplemental Fig.2 (based on samples GSM209708 & GSM209722 compared to the SUP sample GSM209740, provisional accession numbers). This showed that cohesin peaks remained indistinguishable in their relative height and positions whether or not Ssl3 was inactivated. We conclude that, unlike in G1, the loading machinery is dispensable for the stable binding of cohesin to chromosomes in S phase cells. The experiment was repeated twice with slightly changed parameters (16B12 vs 12CA5 anti-HA antibody, 8.5h vs 9h HU arrest at 20C, 3h at 36C vs 3h at 37C inactivation in HU, see samples for details).
2007-11-30 | E-GEOD-8450 | biostudies-arrayexpress
Project description:DNA replication of eukaryotic chromosomes initiates at a number of discrete loci, called replication origins. Distribution and regulation of origins are important for complete duplication of the genome. Here, we determined locations of Orc1 and Mcm6, components of pre-replicative complex (pre-RC), on whole genome of Schizosaccharomyces pombe using a high-resolution tiling array. Pre-RC sites were identified in 460 intergenic regions, where Orc1 and Mcm6 colocalized. By mapping of 5-bromo-2â-deoxyuridine (BrdU)-incorporated DNA in the presence of hydroxyurea (HU), 307 pre-RC sites were identified as early-firing origins. In contrast, 153 pre-RC sites without BrdU incorporation were considered to be late and/or inefficient origins. Early and late origins tend to distribute separately in large chromosome regions. Inactivation of replication checkpoint by deletion of Cds1 resulted in BrdU incorporation with HU specifically at the late origins. An origin-exchange experiment showed that replication timing was not intrinsic to origin but dependent on its surrounding region. Interestingly, pericentromeric heterochromatin and the silent mating type locus replicated in the presence of HU, while the inner centromere or subtelomeric heterochromatin did not. Notably, MCM did not bind to inner centromeres where ORC was located. Thus, replication is differentially regulated in chromosome domains. Keywords: ChIP-chip analysis Experiment Design: ⢠The goal of the experiment â Genome-wide localization of ORC and MCM binding sites and identification of replication origins in Shizosaccaromyces pombe ⢠A brief description of the experiment (e.g., the abstract from the related publication) DNA replication of eukaryotic chromosomes initiates at a number of discrete loci, called replication origins. Distribution and regulation of origins are important for complete duplication of the genome. Here, we determined locations of Orc1 and Mcm6, components of pre-replicative complex (pre-RC), on whole genome of Schizosaccharomyces pombe using a high-resolution tiling array. Pre-RC sites were identified in 460 intergenic regions, where Orc1 and Mcm6 colocalized. By mapping of 5-bromo-2â-deoxyuridine (BrdU)-incorporated DNA in the presence of hydroxyurea (HU), 307 pre-RC sites were identified as early-firing origins. In contrast, 153 pre-RC sites without BrdU incorporation were considered to be late and/or inefficient origins. Early and late origins tend to distribute separately in large chromosome regions. Inactivation of replication checkpoint by deletion of Cds1 resulted in BrdU incorporation with HU specifically at the late origins. An origin-exchange experiment showed that replication timing was not intrinsic to origin but dependent on its surrounding region. Interestingly, pericentromeric heterochromatin and the silent mating type locus replicated in the presence of HU, while the inner centromere or subtelomeric heterochromatin did not. Notably, MCM did not bind to inner centromeres where ORC was located. Thus, replication is differentially regulated in chromosome domains. ⢠Keywords, for example, time course, cell type comparison, array CGH (the use of MGED ontology terms is recommended). Mitosis, Cell cycle, Schizosaccharomyces pombe, Whole-genome, Tiling array, Chromosome II, III array, Orc1, Orc4, Mcm6, BrdU-labeling, cds1Î. ⢠Experimental factors Distribution of the Orc1 and Mcm6 in WT in G1 phase (S. pombe). Distribution of the Orc4 in WT in asynchronous cells (S. pombe). Distribution of BrdU-incorporated DNA in WT and in cds1 deletion mutant in S phase in the presence of HU (S. pombe). ⢠Experimental design ChIP analysis: In all cases, hybridization data for ChIP fraction was compared with WCE (whole cell extract) fraction. Pombe whole-genome tiling array were used. BrdU analysis: Hybridization data for BrdU fraction (replicated DNA) was compared with Whole fraction (unreplicated DNA) or hybridization data for BrdU fraction of cds1Î cells was compared with that of WT cells. Pombe whole-genome tiling array were used. ⢠Quality control steps taken Different subunits of the same complex. Confirmation of several loci by q-PCR. Checking the BrdU-labeled DNA fraction in CsCl gradient by q-PCR or slot-blot analysis. ⢠Links to the publication, any supplemental websites or database accession numbers. GSE6523 Samples used, extract preparation and labelling: ⢠The origin of each biological sample ChIP analysis: Schizosaccharomyces pombe nda3-KM311 cdc10-129 strain harboring pREP81-cdc18 and pREP42-cdt1. BrdU analysis: Schizosaccharomyces pombe wild type (cdc25-22 nmt1-TK) and cds1Î strains. ⢠Manipulation of biological samples and protocols used ChIP analysis: Chromatin immunoprecipitation (ChIP) in G1 arrested cells or asynchronous cells were performed as previously described (Takahashi et al., 2003, EMBO). Hybridization to Affimetrix high-density oligonucleotide array of S. pombe chromosomes 2 and 3 and whole genome tiling array of S. pombe was performed essentially as previously described (Katou et al., 2003, nature) (Lengronne et al., 2004, nature). BrdU analysis: Growing cdc25-22 cells expressing Thymidine Kinase were arrested at G2/M boundary and released in the presence of BrdU and HU. BrdU was incorporated in nascent DNA in following S phase. The genomic DNA was digested by HaeIII and BrdU-labeled DNA was purified in CsCl density gradient centrifugation. Hybridization to Affimetrix high-density oligonucleotide array of S. pombe whole genome tiling array was performed essentially as previously described (Katou et al., 2003, nature) (Lengronne et al., 2004, nature).
2010-06-11 | E-GEOD-6523 | biostudies-arrayexpress
Project description:BACKGROUND: Cells undergoing meiosis perform two consecutive divisions after a single round of DNA replication. During the first meiotic division, homologous chromosomes segregate to opposite poles. This is achieved by (1) the pairing of maternal and paternal chromosomes via recombination producing chiasmata, (2) coorientation of homologous chromosomes such that sister chromatids attach to the same spindle pole, and (3) resolution of chiasmata by proteolytic cleavage by separase of the meiotic-specific cohesin Rec8 along chromosome arms. Crucially, cohesin at centromeres is retained to allow sister centromeres to biorient at the second division. Little is known about how these meiosis I-specific events are regulated. RESULTS: Here, we show that Spo13, a centromere-associated protein produced exclusively during meiosis I, is required to prevent sister kinetochore biorientation by facilitating the recruitment of the monopolin complex to kinetochores. Spo13 is also required for the reaccumulation of securin, the persistence of centromeric cohesin during meiosis II, and the maintenance of a metaphase I arrest induced by downregulation of the APC/C activator CDC20. CONCLUSION: Spo13 is a key regulator of several meiosis I events. The presence of Spo13 at centromere-surrounding regions is consistent with the notion that it plays a direct role in both monopolin recruitment to centromeres during meiosis I and maintenance of centromeric cohesion between the meiotic divisions. Spo13 may also limit separase activity after the first division by ensuring securin reaccumulation and, in doing so, preventing precocious removal from chromatin of centromeric cohesin. Keywords: Meiosis, Cell cycle, Saccharomyces cerevisiae, Chromosome VI tiling array, Spo13, ChIP-chip ⢠Experimental factors Distribution of the Spo13 at Meiosis I. Experiment was performed in Saccharomyces cerevisiae SK1 strain. ⢠Experimental design ChIP analysis: Hybridization data for ChIP fraction was compared with that of SUP (supernatant) fraction. Cerevisiae chromosome VI array was used. ⢠Quality control steps taken Checking of the ChIP fraction by Western blotting. Mock hybridisation of samples immunoprecipitated from cells containing no tag recognized by antibody used. Sup swapping. Samples used, extract preparation and labelling: ⢠The origin of each biological sample Saccharomyces cerevisiae (SK1). ⢠Manipulation of biological samples and protocols used Chromatin immunoprecipitation (ChIP) and hybridization to Affimetrix high-density oligonucleotide arrays of S. cerevisiae chromosome VIwere performed essentially as previously described (Katou et al., 2003, nature) (Lengronne et al., 2004, nature). ⢠Technical protocols for preparing the hybridization extract The chromatin-immunprecipates were eluted and incubated over night at 65ºC 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 95ºC. DNA fragments were end-labeled by addition of 25 U of Terminal Transferase and 1 nmol Biotin-N6ddATP (NEN) for 1 hour at 37ºC as previously described by Winzeler et al. (Science. 281, 1194-1197, 1998). The entire sample was used for hybridization. ⢠Hybridization procedures and parameters: Hybridization, blocking and washing were carried out as previously described (Lengronne et al. Nature 2004). 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 3âbiotin labelled control oligonucleotide (oligo B2, Affymetrix). Samples were denatured at 100ºC for 10 minutes, and then put on ice before being hybridized for 16 hours at 42ºC in a hybridization oven (GeneChip Hybridization Oven 640, Affymetrix). Washing and scanning protocol provided by Affymetrix was performed automatically on a fluidics station (GeneChip fluidics station 450, Affymetrix). ⢠Measurement data and specifications: Arrays were scanned using the Genechip Scanner3000 7G following the library array description. All the cel files data and processed data files can be downloaded from GEO database. The primary analysis of tiling chip data was performed following exactly the statistical algorithm used for Affymetrix GeneChip Operating Software (GCOS). The detailed information for the algorithm used can be downloaded from the Affymetrix web site. The analysis is available on request. For the ChrVI array, one unit for analysis (locus) was set to 300bp. Fold change value, change p-value, and detection p-value for each locus were obtained by primary analysis. For the discrimination of positive and negative signals for the binding, we used three criteria as follows. First, the reliability of the signal strength was judged by detection p-value of each locus (p-valueâ¤0.025). Secondly, reliability of binding ratio was judged by change p-value (p-valueâ¤0.0025). Thirdly, clusters consisting of at least 900bp contiguous loci that satisfied the above two criteria were selected, because it is known that a single site of protein-DNA interaction resulted in immuno-precipitation of DNA fragments that hybridized not only to the locus of the actual binding site but also to its neighbors. ⢠Array Design: General array design: in situ synthesized arrays by Affymetrix Availability of arrays: commercially available from Affymetrix Location and ID of each spot on arrays: available from Affymetrix on request Probe type: oligonucleotide The arrays used in this study can be purchased from Affymetrix: Chromosome VI S.cerevisiae: rikDACFC6, P/N# 510636 GSM108198 was used for normalization of GSM108511.
2010-06-11 | E-GEOD-4813 | biostudies-arrayexpress
Project description:Cohesin is a multisubunit complex that mediates sister-chromatid cohesion. Its Smc1 and Smc3 subunits possess ABC-like ATPases at one end of 50 nm long coiled coils. At the other ends are pseudosymmetrical hinge domains that interact to create V-shaped Smc1/Smc3 heterodimers. N- and C-terminal domains within cohesin's kleisin subunit Scc1 bind to Smc3 and Smc1 ATPase heads respectively, thereby creating a huge tripartite ring. It has been suggested that cohesin associates with chromosomes by trapping DNA within its ring. Opening of the ring due to cleavage of Scc1 by separase destroys sister-chromatid cohesion and triggers anaphase. We show that cohesin's hinges are not merely dimerization domains. They are essential for cohesin's association with chromosomes, which is blocked by artificially holding hinge domains together but not by preventing Scc1's dissociation from SMC ATPase heads. Our results suggest that entry of DNA into cohesin's ring requires transient dissociation of Smc1 and Smc3 hinge domains. Keywords: Cohesin loading, Scc1, Smc1, Smc3, Hinge opening, ChIP-chip â?¢ Experimental factors Distribution of the mutant and wild type form of cohesin in mitotic G2 phase. â?¢ Experimental design ChIP analysis: In all cases, hybridization data for ChIP fraction was compared with SUP (supernatant) fraction. SUP fraction is equal to WCE (Whole Cell Extract) fraction. Essentially WCE or SUP fraction of any cell cycle phase can be used for normalization, and there was no effect on protein binding profiles. Cerevisiae chromosome VI array was used. â?¢ Quality control steps taken Confirmation using different tags. Confirmation by q-PCR. Checking of the ChIP fraction by Western blotting. Mock hybridisation of samples immuno-precipitated from cells containing no tag recognized by antibody used. Samples used, extract preparation and labelling: â?¢ The origin of each biological sample Saccharomyces cerevisiae (W303). â?¢ Manipulation of biological samples and protocols used Chromatin immunoprecipitation (ChIP) and hybridization to Affimetrix high-density oligonucleotide arrays of S. cerevisiae chromosome VIwere performed essentially as previously described (Katou et al., 2003, nature) (Lengronne et al., 2004, nature). â?¢ Technical protocols for preparing the hybridization extract The chromatin-immunprecipates were eluted and incubated over night at 65ºC 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 95ºC. DNA fragments were end-labeled by addition of 25 U of Terminal Transferase and 1 nmol Biotin-N6ddATP (NEN) for 1 hour at 37ºC as previously described by Winzeler et al. (Science. 281, 1194-1197, 1998). The entire sample was used for hybridization. â?¢ Hybridization procedures and parameters: Hybridization, blocking and washing were carried out as previously described (Lengronne et al. Nature 2004). 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 100ºC for 10 minutes, and then put on ice before being hybridized for 16 hours at 42ºC in a hybridization oven (GeneChip Hybridization Oven 640, Affymetrix). Washing and scanning protocol provided by Affymetrix was performed automatically on a fluidics station (GeneChip fluidics station 450, Affymetrix). â?¢ Measurement data and specifications: Arrays were scanned using the Genechip Scanner3000 7G following the library array description. All the cel files data and processed data files can be downloaded from GEO database. The primary analysis of tiling chip data was performed following exactly the statistical algorithm used for Affymetrix GeneChip Operating Software (GCOS). The detailed information for the algorithm used can be downloaded from the Affymetrix web site. The analysis is available on request. For the ChrVI array, one unit for analysis (locus) was set to 300bp. Fold change value, change p-value, and detection p-value for each locus were obtained by primary analysis. For the discrimination of positive and negative signals for the binding, we used three criteria as follows. First, the reliability of the signal strength was judged by detection p-value of each locus (p-valueâ?¤0.025). Secondly, reliability of binding ratio was judged by change p-value (p-valueâ?¤0.025). Thirdly, clusters consisting of at least 900bp contiguous loci that satisfied the above two criteria were selected, because it is known that a single site of protein-DNA interaction resulted in immuno-precipitation of DNA fragments that hybridized not only to the locus of the actual binding site but also to its neighbors. â?¢ Array Design: General array design: in situ synthesized arrays by Affymetrix Availability of arrays: commercially available from Affymetrix Location and ID of each spot on arrays: available from Affymetrix on request Probe type: oligonucleotide The arrays used in this study can be purchased from Affymetrix: Chromosome VI S.cerevisiae: rikDACFC6, P/N# 510636
2010-06-09 | E-GEOD-4827 | biostudies-arrayexpress
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 â?¢ Experimental factors Distribution of Cse4, Ndc10, Rts1 in mitotic G2 phase and meiosis I (S. cerevisiae). Distribution of Rec8 in meiosis I (S.cerevisiae). All experiments were performed in cells with the same genetic background (Saccharomyces cerevisiae SK1). â?¢ Experimental design ChIP analysis: In all cases, hybridization data for ChIP fraction was compared with SUP (supernatant) fraction. SUP fraction is same as WCE fraction. â?¢ Quality control steps taken Duplication, confirmation using different tags, and different subunits of the same complex. Confirmation of protein distribution using deletion mutant strain. Confirmation of several loci by q-PCR. Checking of the ChIP fraction by Western blotting. Checking of the ChIP fraction by swapping SUP fraction. Samples used, extract preparation and labelling: â?¢ The origin of each biological sample Saccharomyces cerevisiae (SK1) . â?¢ Manipulation of biological samples and protocols used Chromatin immunoprecipitation (ChIP) and hybridization to Affimetrix high-density oligonucleotide arrays of S. cerevisiae chromosome VI was performed essentially as previously described (Katou et al., 2003, nature) (Lengronne et al., 2004, nature). â?¢ Technical protocols for preparing the hybridization extract The chromatin-immunprecipates were eluted and incubated over night at 65ºC 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 95ºC. DNA fragments were end-labeled by addition of 25 U of Terminal Transferase and 1 nmol Biotin-N6ddATP (NEN) for 1 hour at 37ºC as previously described by Winzeler et al. (Science. 281, 1194-1197, 1998). The entire sample was used for hybridization. â?¢ Hybridization procedures and parameters: Hybridization, blocking and washing were carried out as previously described (http://everythingchromosomevi.gsc.riken.go.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 100ºC for 10 minutes, and then put on ice before being hybridized for 16 hours at 42ºC in a hybridization oven (GeneChip Hybridization Oven 640, Affymetrix). Washing and scanning protocol provided by Affymetrix was performed automatically on a fluidics station (GeneChip fluidics station 450, Affymetrix). â?¢ Measurement data and specifications: Arrays were scanned using the Genechip Scanner3000 7G following the library array description. All the raw data files can be downloaded from GEO database. The primary analysis of tiling chip data was performed following exactly the statistical algorithm used for Affymetrix GeneChip Operating Software (GCOS). The detailed information for the algorithm used can be downloaded from the Affymetrix web site at http://www.affymetrix.com/support/technical/technotes/statistical_reference_guide.pdf. The analysis is available on request. For the ChrVI array, one unit for analysis (locus) was set to 300bp. Fold change value, change p-value, and detection p-value for each locus were obtained by primary analysis. For the discrimination of positive and negative signals for the binding, we used three criteria as follows. First, the reliability of the signal strength was judged by detection p-value of each locus (p-valueâ?¤0.025 for cerevisiae). Secondly, reliability of binding ratio was judged by change p-value (p-valueâ?¤0.025 for cerevisiae). Thirdly, clusters consisting of at least 900bp contiguous loci that satisfied the above two criteria were selected, because it is known that a single site of protein-DNA interaction resulted in immuno-precipitation of DNA fragments that hybridized not only to the locus of the actual binding site but also to its neighbors. â?¢ Array Design: General array design: in situ synthesized arrays by Affymetrix Availability of arrays: commercially available from Affymetrix Location and ID of each spot on arrays: available from Affymetrix on request Probe type: oligonucleotide The arrays used in this study can be purchased from Affymetrix: Chromosome VI S.cerevisiae: rikDACFC6, P/N# 510636
2010-06-11 | E-GEOD-4791 | biostudies-arrayexpress
Project description:DNA topoisomerases solve topological problems during chromosome metabolism. We investigated where and when Top1 and Top2 are recruited on replicating chromosomes and how their inactivation affects fork integrity and DNA damage checkpoint activation. We show that, in the context of replicating chromatin, Top1 and Top2 act within a 600 bp region spanning the moving forks. Top2 exhibits additional S-phase clusters at specific intergenic loci, mostly containing promoters. TOP1 ablation does not affect fork progression and stability and does not cause activation of the Rad53 checkpoint kinase. top2 mutants accumulate sister chromatid junctions in S phase without affecting fork progression and activate Rad53 at the M/G1 transition. top1 top2 double mutants exhibit fork block and processing, and phosphorylation of Rad53 and γH2A in S phase. The exonuclease Exo1 influences fork processing and DNA damage checkpoint activation in top1 top2 mutants. Our data are consistent with a coordinated action of Top1 and Top2 in counteracting the accumulation of torsional stress and sister chromatid entanglement at replication forks, thus preventing the diffusion of topological changes along large chromosomal regions. A failure in resolving fork-related topological constrains during S phase may therefore result in abnormal chromosome transitions, DNA damage checkpoint activation and chromosome breakage during segregation. Keywords: ChIP-chip analysis S. cerevisiae chromosomes IIIâV, and chromosome VI highdensity oligonucleotide microarrays were provided by Affymetrix Custom Express Service (SC3456a520015F, P/N 520015; rikDACF, P/N 510636, respectively). Sequence and position of oligonucleotides on the microarrays are available from Affymetrix. ChIP was carried out as previously described (Katou et al. 2003; Katou et al. 2006): we disrupted 1.5 x 108 cells byMulti-beads shocker (MB400U, Yasui Kikai) using glass beads. Anti-HA monoclonal antibody HA.11 (16B12) (CRP Inc.) and anti-Flag monoclonal antibody M2 (Sigma-Aldrich) were used for chromatin immunoprecipitation. ChIPed DNA was purified and amplified by random priming as described (Katou et al. 2003): a total of 10 μg of amplified DNA was digested with DNaseI to a mean size of 100 bp, purified, and the fragments were end-labelled with biotin-N6-ddATP23. Hybridization, washing, staining and scanning were performed according to the manufacturerâs instruction (Affymetrix). Primary data analyses were carried out using the Affymetrix microarray Suite version 5.0 software to obtain hybridization intensity, fold change value, change P-value and detection P-value for each locus. For the discrimination of positive and negative signals for the binding, we compared ChIPed fraction with supernatant fraction by using three criteria. First, the reliability of strength of signal was judged by detection P-value of each locus (P â¥0.025). Second, reliability of binding ratio was judged by change P-value (P ⥠0.025). Third, clusters consisting of at least three contiguous loci that filled the above Bermejo et al. 26 two criteria were selected, because it was known that a single site of proteinâDNA interaction will result in immunoprecipitation of DNA fragments that hybridized not only to the locus of the actual binding site but also to its neighbours. For the analyses of BrdU incorporation, cells were fixed by ice-cold buffer containing 0.1% azide, and then total DNA from 3 x108 cells was purified. DNA was sheared to 300 bp by sonication, denatured, and mixed with 2μg anti-BrdU monoclonal antibody (2B1D5F5H4E2; MBL). Antibody-bound and unbound fractions were subsequently purified, amplified, labelled and hybridized to the DNA chip.
2010-06-05 | E-GEOD-8305 | biostudies-arrayexpress
Project description:Sister chromatid cohesion, established during replication by the protein complex Cohesin, is essential for both chromosome segregation and double-strand break (DSB) repair. Normally cohesion formation is strictly limited to the S-phase of the cell cycle, but DSBs can trigger cohesion also after DNA replication has been completed. The function of this damage-induced cohesion remains unknown. In this investigation we show that it is essential for repair in post-replicative cells in yeast. Furthermore, it is established genome-wide after induction of a single DSB, and controlled by the DNA damage response and Cohesin regulating factors. We thus define a cohesion establishment pathway that is independent of DNA duplication and acts together with cohesion formed during replication in sister chromatid-based DSB repair. Keywords: ChIP-chip analysis Scc2, Scc1, and rH2AX distribution with or without DSB in wild type and mutant strains. DSB was induced by galactose promoter driven HO. All yeast strains were haploid and of W303 origin (ade2-1, trp1-1, can1-100, leu2-3, 112, his3-11, 15, ura3, RAD5). DNA was purified and amplified as previously described by Katou et al. (nature, 2003), and hybridized to SC3456a 52005F or S.cerevisiae Tiling 1.0F arrays, Part#520286 (Affymetrix). Scc2 was C- terminally tagged with 6HIS-3xFLAG, while Mcd1UNCL was marked with 3HA epitopes. Anti-FLAG antibody M2 (Sigma), anti-HA antibody (Babco), or anti γ-H2A-antobodies kindly provided by A. Verreault were used for immuno-precipitations.
2010-06-10 | E-GEOD-8270 | biostudies-arrayexpress