Genome-wide replication timing in the mutants deleted for telomere-binding proteins in S. pombe
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ABSTRACT:
ORGANISM(S): Schizosaccharomyces pombe
PROVIDER: GSE94812 | GEO | 2019/03/31
REPOSITORIES: GEO
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Project description:Eukaryotic DNA replication initiates from multiple sites on each chromosome called replication origins. In the budding yeast Saccharomyces cerevisiae, origins are defined at discrete sites. Regular spacing and diverse firing characteristics of origins are thought to be required for efficient completion of replication, especially in the presence of replication stress. However, a S. cerevisiae chromosome III harboring multiple origin deletions has been reported to replicate relatively normally, and yet how an origin-deficient chromosome could accomplish successful replication remains unkown. To address this issue, we deleted seven well-characterized origins from chromosome VI, and found that thsese deletions do not cause gross growth defects even in the presence of replication inhibitors. We demonstrated that the origin deletions do cause a strong decrease in the binding of the origin recognition complex. Unexpectedly, replication profiling of this chromosome showed that DNA replication initiates from non-canonical loci around deleted origins in yeast. These results suggest that replication initiation can be unexpectedly flexible in this organism. In this study, we aimed to establish an independent system to investigate how an origin-deficient chromosome is replicated. To this end, we systematically deleted seven well-characterized origins on the left arm of S. cerevisiae chromosome VI and analyzed (1) Orc2 localization during G2/M arrest and (2) BrdU incorporation during synchronous release from G1 arrest into S-phase, and compared the results to wild-type cell signals. For Orc2 ChIP-Chip experiments, Orc-bound DNA was isolated from Orc2-2Xlinker-3XFlag epitope-tagged cells arrested in G2/M using antibodies against Flag. For BrdU ChIP-Chip experiments, actively replicating DNA was isolated from cells harboring a single integrated BrdU incorporation vector released synchronously into 200mM HU using antibodies against BrdU. Immunoprecipitated and input (Orc2) or G1 (BrdU) DNA was then amplified and competitively hybridized to high-resolution strand-specific microarrays covering chromosomes III, VI, and XII.
2014-09-26 | E-GEOD-61743 | 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:Chromosomal DNA replication involves the coordinated activity of hundreds to thousands of replication origins. Individual replication origins are subject to epigenetic regulation of their activity during S-phase, resulting in differential efficiencies and timings of replication initiation during S-phase. This regulation is thought to involve chromatin structure and organization into timing domains with differential ability to recruit limiting replication factors. Rif1 has recently been identified as a genome-wide regulator of replication timing in fission yeast and in mammalian cells. However, previous studies in budding yeast have suggested that Rif1’s role in controlling replication timing may be limited to subtelomeric domains and derives from its established role in telomere length regulation. We have analyzed replication timing by analyzing BrdU incorporation genome-wide, and report that Rif1 regulates the timing of late/dormant replication origins throughout the S. cerevisiae genome. Analysis of pfa4∆ cells, which are defective in palmitoylation and membrane association of Rif1, suggests that replication timing regulation by Rif1 is independent of its role in localizing telomeres to the nuclear periphery. Intra-S checkpoint signaling is intact in rif1∆ cells, and checkpoint-defective mec1∆ cells do not comparably deregulate replication timing, together indicating that Rif1 regulates replication timing through a mechanism independent of this checkpoint. Our results indicate that the Rif1 mechanism regulates origin timing irrespective of proximity to a chromosome end, and suggest instead that telomere sequences merely provide abundant binding sites for proteins that recruit Rif1. Still, the abundance of Rif1 binding in telomeric domains may facilitate Rif1-mediated repression of non-telomeric origins that are more distal from centromeres. 30 total samples: (6 samples - BrdU- HU arrest 45min with 2 replicates, strains: WT, rif1 delta, pfa4 delta) (12 samples -S-phase BrdU time course with 2 replicates at 25 and 35 min, strains: WT, rif1 delta, mec1_100) (12 samples - S-phase BrdU time course with 2 replicates at 25 and 35 min, strains: sml1 delta, sml1 delta rif1 delta, sml1 delta mec1 delta)
2014-06-01 | E-GEOD-55130 | 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-2’-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
2007-03-05 | GSE6523 | GEO
Project description:Cdc7/Hsk1 is a conserved kinase required for initiation of DNA replication that potentially regulates timing and locations of replication origin firing. Here, we show that viability of fission yeast hsk1∆ cells can be restored by loss of mrc1, which is required for maintenance of replication fork integrity, by cds1∆, or by a checkpoint-deficient mutant of mrc1. In these mutants, normally inactive origins are activated in the presence of HU and binding of Cdc45 to MCM is stimulated. mrc1∆ bypasses hsk1∆ more efficiently because of its checkpoint-independent inhibitory functions. Unexpectedly, hsk1∆ is viable at 37°C. More DNA is synthesized, and some dormant origins fire in the presence of HU at 37°C. On the other hand, hsk1∆ bypass strains grow poorly at 25°C compared to at higher temperatures. Our results show that Hsk1 functions for DNA replication can be bypassed by different genetic backgrounds as well as under varied physiological conditions, providing additional evidence for plasticity of the replication program in eukaryotes. BrdU incorporation profiles at early S-phase in mrc1∆, cds1∆ and hsk1-89 mutants.
2011-08-26 | GSE31650 | GEO
Project description:modENCODE_submission_710 This submission comes from a modENCODE project of David MacAlpine. For full list of modENCODE projects, see http://www.genome.gov/26524648 Project Goal: Early origins of replication were identified by treating cells with hydroxyurea (HU), a potent inhibitor of nucleotide synthesis, in the presence of the nucleotide analogue BrdU. Treatment of synchronized S2-DRSC cells with HU stalls replication forks and activates the intra S-phase checkpoint, thereby limiting BrdU incorporation to those sequences immediately adjacent to early activating replication origins. BrdU enriched sequences surrounding early origins of replication are then enriched by immunoprecipitation with an anti-BrdU antibody. Early origins are then detected by hybridization to Agilent genomic tiling arrays. Peaks are called using MA2C (http://liulab.dfci.harvard.edu/MA2C/MA2C.htm) Keywords: CHIP-chip For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf
2009-07-29 | GSE17286 | GEO
Project description:modENCODE_submission_709 This submission comes from a modENCODE project of David MacAlpine. For full list of modENCODE projects, see http://www.genome.gov/26524648 Project Goal: Early origins of replication were identified by treating cells with hydroxyurea (HU), a potent inhibitor of nucleotide synthesis, in the presence of the nucleotide analogue BrdU. Treatment of synchronized Kc167 cells with HU stalls replication forks and activates the intra S-phase checkpoint, thereby limiting BrdU incorporation to those sequences immediately adjacent to early activating replication origins. BrdU enriched sequences surrounding early origins of replication are then enriched by immunoprecipitation with an anti-BrdU antibody. Early origins are then detected by hybridization to Agilent genomic tiling arrays. Peaks are called using MA2C (http://liulab.dfci.harvard.edu/MA2C/MA2C.htm) Keywords: CHIP-chip For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf
2009-07-29 | GSE17285 | GEO
Project description:modENCODE_submission_711 This submission comes from a modENCODE project of David MacAlpine. For full list of modENCODE projects, see http://www.genome.gov/26524648 Project Goal: Early origins of replication were identified by treating cells with hydroxyurea (HU), a potent inhibitor of nucleotide synthesis, in the presence of the nucleotide analogue BrdU. Treatment of synchronized ML-DmBG3-c2 cells with HU stalls replication forks and activates the intra S-phase checkpoint, thereby limiting BrdU incorporation to those sequences mmediately adjacent to early activating replication origins. BrdU enriched sequences surrounding early origins of replication are then enriched by immunoprecipitation with an anti-BrdU antibody. Early origins are then detected by hybridization to Agilent genomic tiling arrays. Peaks are called using MA2C (http://liulab.dfci.harvard.edu/MA2C/MA2C.htm) Keywords: CHIP-chip For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf
2009-07-29 | GSE17287 | GEO
Project description:Faithful duplication of DNA is essential for the maintenance of genomic stability in all organisms. DNA synthesis proceeds bi-directionally with continuous synthesis of leading strand DNA and discontinuous synthesis of lagging strand DNA. Herein, we describe a method of enriching and Sequencing of Protein-Associated Nascent strand DNA (eSPAN) to detect whether a protein binds the leading- and lagging-strands of DNA replication forks. We show that Pol-epsilon, PCNA, Cdc45, Mcm6 and Mcm10 preferentially associate with leading strands, whereas Pol-alpha, Pol32, Pol-delta, Rfa1 and Rfc1 associate with lagging strands of hydroxyurea (HU)-stalled replication forks. In contrast, PCNA is enriched at lagging strands of normal replication forks in wild type cells and HU-stalled forks in cells lacking Elg1. These studies demonstrate a strategy to reveal proteins at leading and lagging strands of DNA replication forks, and suggest that the unloading of PCNA from lagging strands of HU-stalled replication forks helps maintain genome integrity. We synchronized yeast cells at G1 and released into early S phase in the presence of BrdU, a nucleotide analog that can be incorporated into newly synthesized DNA strand, and hydroxyurea (HU), a ribonucleotide reductase inhibitor. HU has no effect on initiation of DNA replication at early replication origins, but inhibit late replication firing. In addition, replication forks are stalled due to depletion of dNTPs. We then performed chromatin-immunoprecipitation of 12 proteins of interest following a standard procedure. Protein-bound DNAs were then reverse-crosslinked and double strand DNA was denatured. Nascent DNA was enriched by immunoprecipitation using anti-BrdU antibodies. The recovered ssDNA was first marked with ligation to one oligo at 3M-bM-^@M-^Y end before conversion to dsDNA for library preparation and sequencing. In this way, the directionality of ssDNA and therefore strand information of each sequenced DNA were known. The sequencing tag was mapped to both Watson (red) and Crick (blue) strands of the reference genome. In addition to ChIP-eSPAN, we also performed BrdU-IP and single strand DNA sequence (BrdU-ssSeq) and protein ChIP followed by single-strand DNA sequencing (ChIP-ssSeq) for each corresponding ChIP-eSPAN experiment. We also performed Mcm4 and Mcm6 ChIP-seq using cells synchronized at G1 phase of the cell cycle for identification of replication origins in comparison with published dataset. Some protein ChIP-ssSeq and ChIP-eSPAN experiments were repeated and the data fits well each other. Therefore, we did not repeat all protein ChIP-ssSeq and ChIP-eSPAN experiments.
2014-10-29 | E-GEOD-52614 | biostudies-arrayexpress
Project description:Wild-type and isogenic H3K37R yeast cultures were grown in medium containing 2% raffinose as carbone source. Cells were synchronized in G1 with alpha factor. To half culture (100ml), glucose (2% final concentration) and 1.3ml BrdU (50mg/ml stock) and 1.3ml BrdU (50mg/ml stock) was added. To the other half, galactose (2% final concentration) and 1.3ml BrdU (50mg/ml stock). Both flasks were incubated for further 30min at 30C, then cell were collected by centrifugation and resuspended into 100ml of 30C warmed YPA-2%Glucose or YPA-2%Galactose medium containing 25ml HU (2M stock) plus 1.2 ml BrdU (50mg/ml stock) and incubated for 1 hour and 10minutes. YPA-Glucose and YPA-Galactose cultures were immediately transferred to ice/water bath and replication was stopped by addition of NaN3 and cells were processed for DNA immunoprecipitation with anti BrdU antibody.
2021-04-30 | E-MTAB-9999 | biostudies-arrayexpress