Genome-wide map of DNA replication origin in Schizosaccharomyces pombe
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ABSTRACT:
ORGANISM(S): Schizosaccharomyces pombe
PROVIDER: GSE125335 | GEO | 2019/01/19
REPOSITORIES: GEO
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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: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:The chromatin-based rules governing the selection and activation of replication origins remain to be elucidated. It is believed that DNA replication initiates from open chromatin domains, thus replication origins residing in regulatory elements that are located at open and active chromatin. However, we report here that lysine specific demethylase 1 (LSD1), which biochemically catalyzes H3K4me1/2 demethylation to favor chromatin condensation, interacts with the DNA replication machinery. We found that LSD1 level peaks in early S phase. We demonstrated that LSD1 promotes DNA replication by facilitating origin firing in euchromatic regions and through regulating replication timing. Indeed, euchromatic zones enriched in H3K4me2 are the preferred sites for pre-RC binding in early replication. Remarkably, LSD1 deficiency leads to a genome-wide switch from early to late in replication timing. We showed that LSD1-promoted DNA replication is mechanistically linked to the loading of TICRR (TopBP1-Interacting Checkpoint and Replication Regulator) onto the pre-RC and subsequent recruitment of the initiator Cdc45 during origin firing. Together, these results reveal an unexpected role for LSD1 in euchromatic origin firing and replication timing.
2022-03-07 | GSE157469 | GEO
Project description:The chromatin-based rules governing the selection and activation of replication origins remain to be elucidated. It is believed that DNA replication initiates from open chromatin domains, thus replication origins residing in regulatory elements that are located at open and active chromatin. However, we report here that lysine specific demethylase 1 (LSD1), which biochemically catalyzes H3K4me1/2 demethylation to favor chromatin condensation, interacts with the DNA replication machinery. We found that LSD1 level peaks in early S phase. We demonstrated that LSD1 promotes DNA replication by facilitating origin firing in euchromatic regions and through regulating replication timing. Indeed, euchromatic zones enriched in H3K4me2 are the preferred sites for pre-RC binding in early replication. Remarkably, LSD1 deficiency leads to a genome-wide switch from early to late in replication timing. We showed that LSD1-promoted DNA replication is mechanistically linked to the loading of TICRR (TopBP1-Interacting Checkpoint and Replication Regulator) onto the pre-RC and subsequent recruitment of the initiator Cdc45 during origin firing. Together, these results reveal an unexpected role for LSD1 in euchromatic origin firing and replication timing.
2022-03-07 | GSE157468 | GEO
Project description:The chromatin-based rules governing the selection and activation of replication origins remain to be elucidated. It is believed that DNA replication initiates from open chromatin domains, thus replication origins residing in regulatory elements that are located at open and active chromatin. However, we report here that lysine specific demethylase 1 (LSD1), which biochemically catalyzes H3K4me1/2 demethylation to favor chromatin condensation, interacts with the DNA replication machinery. We found that LSD1 level peaks in early S phase. We demonstrated that LSD1 promotes DNA replication by facilitating origin firing in euchromatic regions and through regulating replication timing. Indeed, euchromatic zones enriched in H3K4me2 are the preferred sites for pre-RC binding in early replication. Remarkably, LSD1 deficiency leads to a genome-wide switch from early to late in replication timing. We showed that LSD1-promoted DNA replication is mechanistically linked to the loading of TICRR (TopBP1-Interacting Checkpoint and Replication Regulator) onto the pre-RC and subsequent recruitment of the initiator Cdc45 during origin firing. Together, these results reveal an unexpected role for LSD1 in euchromatic origin firing and replication timing.
2022-03-07 | GSE157470 | GEO
Project description:Mrc1 marks early-firing origins and coordinates timing and efficiency of initiation in fission yeast
| PRJNA139537 | ENA
Project description:DNA replication is initiated at multiple sites or origins enriched with AT-rich sequences at various times during the S-phase. While current studies of genome-wide DNA replication profiles have focused on the timing of replication and the location of origins, the efficiency of replication/firing at various origins remains unclear. In this study, we show different efficiencies of DNA replication at various loci by using ORF-specific DNA microarrays. DNA copy-number increases as a function of time at individual loci are approximated to near-sigmoidal models for estimation of replication initiation and completion timings in HU-challenged cells. Duplicating times (from initiation to completion) vary from loci to loci, partly contributing to various firing efficiencies at origins. DNA replication timing profiles are strikingly similar to the reported patterns of enriched ssDNA, suggesting that majority stalled forks are restored for resumption of DNA replication. Although the DNA replication timing profiles are disrupted in HU-challenged cds1? cells, ~85% of potential origins overlapped with those found in wild type cells, significantly, most of which represents inefficiently fired origins in wild type cells. Together, our result indicates that replication checkpoint plays a role in monitoring efficient origins and thus maintaining global DNA replication patterns in HU-challenged cells. Keywords: WT or Cds1 HU synchronized cells released in HU free media and harvested at different time points vs WT or Cds1 synchronized with HU for 3 hrs. We analyzed 32 arrays for WT and 38 arrays for Cds1 cells which were synchronized with HU and released in HU free media and harvested at different time points. At least two biological repeats were done for each time points.
2007-08-14 | E-GEOD-6977 | biostudies-arrayexpress
Project description:The origin recognition complex (ORC) nucleates DNA replication initiation in eukaryotic cells. This six-protein complex binds replication origin DNA, recruits other initiation factors and facilitates loading of the DNA helicase. Studying the function of individual ORC subunits during pre-RC formation has been hampered by the requirement of most subunits for DNA binding. In this study, we investigate the function of the S. cerevisiae Orc6 subunit, the only subunit not required for DNA binding. In vivo, depletion of Orc6 inhibits pre-replicative complex (pre-RC) assembly and maintenance. In vitro, ORC lacking Orc6 fails to interact with Cdt1 and to load the Mcm2-7 helicase onto origin DNA. We demonstrate that two regions of Orc6 bind Cdt1 directly and that the extreme C-terminus of Orc6 (Orc6-CTD) interacts tightly with the remaining five ORC subunits. Replacing Orc6 with a fusion protein linking Cdt1 to the Orc6-CTD results in an ORC complex that loads Mcm2-7 onto DNA. Interestingly, this complex can only perform a single round of Mcm2-7 loading, suggesting that a dynamic association of Cdt1 with ORC is required for multiple rounds of pre-RC assembly. Keywords: ChIP-chip
2007-11-14 | GSE9318 | GEO
Project description:A form of dwarfism known as Meier-Gorlin syndrome (MGS) is caused by recessive mutations in one of six different genes (ORC1, ORC4, ORC6, CDC6, CDT1, and MCM5). These genes encode components of the pre-replication complex, which assembles at origins of replication prior to S phase. Also, variants in two additional replication initiation genes have joined the list of causative mutations for MGS (Geminin and CDC45). The identity of the causative MGS genetic variants strongly suggests that some aspect of replication is amiss in MGS patients; however, little evidence has been obtained regarding what aspect of chromosome replication is faulty. Since the site of one of the missense mutations in the human ORC4 alleles is conserved between humans and yeast, we sought to determine in what way this single amino acid change affects the process of chromosome replication, by introducing the comparable mutation into yeast (orc4Y232C). To examine early replication dynamics on a genome-wide scale in orc4Y232C cells, we utilized an assay that was previously developed in our lab. This assay uses microarray hybridization to measure the levels of single stranded DNA exposed at replication forks. While we do not fully understand the molecular processes that give rise to peaks of different amplitudes—e.g., number of cells that have activated a particular origin vs. amount of ssDNA revealed at different forks—the results from different replicates of the experiment are highly reproducible. We find that origins that are known to fire early and are efficient produce the peaks of greatest magnitude, while later firing and less efficient origins produce smaller or no peaks in this assay. The characteristic time and/or efficiency of origin firing within the S phase is altered for at least 15% of the 300 yeast origins. Among the origins with delayed/reduced origin firing are normally early-firing origins adjacent to centromeres.
2017-10-06 | GSE104671 | GEO
Project description:DNA replication is initiated at multiple sites or origins enriched with AT-rich sequences at various times during the S-phase. While current studies of genome-wide DNA replication profiles have focused on the timing of replication and the location of origins, the efficiency of replication/firing at various origins remains unclear. In this study, we show different efficiencies of DNA replication at various loci by using ORF-specific DNA microarrays. DNA copy-number increases as a function of time at individual loci are approximated to near-sigmoidal models for estimation of replication initiation and completion timings in HU-challenged cells. Duplicating times (from initiation to completion) vary from loci to loci, partly contributing to various firing efficiencies at origins. DNA replication timing profiles are strikingly similar to the reported patterns of enriched ssDNA, suggesting that majority stalled forks are restored for resumption of DNA replication. Although the DNA replication timing profiles are disrupted in HU-challenged cds1? cells, ~85% of potential origins overlapped with those found in wild type cells, significantly, most of which represents inefficiently fired origins in wild type cells. Together, our result indicates that replication checkpoint plays a role in monitoring efficient origins and thus maintaining global DNA replication patterns in HU-challenged cells. Keywords: WT or Cds1 HU synchronized cells released in HU free media and harvested at different time points vs WT or Cds1 synchronized with HU for 3 hrs.
2007-08-14 | GSE6977 | GEO