DNA re-replication is susceptible to nucleotide level mutagenesis
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PROVIDER: PRJNA511875 | ENA |
REPOSITORIES: ENA
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Project description:The sources of genome instability, a hallmark of cancer, remain incompletely understood. One potential source is DNA re-replication, which arises when the mechanisms that prevent re-initiation of replication origins within a single cell cycle are compromised. Using the budding yeast Saccharomyces cerevisiae, we previously showed that DNA re-replication is extremely potent at inducing gross chromosomal alterations and that this arises in part because of the susceptibility of re-replication forks to break. Here, we examine the ability of DNA re-replication to induce nucleotide level mutations. During normal replication these mutations are restricted by three overlapping error avoidance mechanisms: the nucleotide selectivity of replicative polymerases, their proofreading activity, and mismatch repair. Using lys2InsEA14, a frameshift reporter that is poorly proofread, we show that re-replication induces up to a 30x higher rate of frameshift mutations and that this mutagenesis is due to passage of the re-replication fork, not secondary to re-replication fork breakage. Re-replication can also induce comparable rates of frameshift and base substitution mutations in a more general mutagenesis reporter CAN1, when the proofreading activity of DNA polymerase ε is inactivated. Finally, we show that the induction of lys2InsEA14 frameshift mutations by re-replication is dependent on mismatch repair. These results suggest that the mismatch repair associated with re-replication is attenuated, although at most sequences DNA polymerase proofreading provides enough error correction to mitigate the mutagenic consequences. Thus, re-replication can facilitate nucleotide level mutagenesis in addition to inducing gross chromosomal alterations, broadening its potential role in genome instability.
2018-12-27 | GSE124382 | GEO
Project description:The sources of genome instability, a hallmark of cancer, remain incompletely understood. One potential source is DNA rereplication, which arises when the mechanisms that prevent the reinitiation of replication origins within a single cell cycle are compromised. Using the budding yeast Saccharomyces cerevisiae, we previously showed that DNA rereplication is extremely potent at inducing gross chromosomal alterations and that this arises in part because of the susceptibility of rereplication forks to break. Here, we examine the ability of DNA rereplication to induce nucleotide-level mutations. During normal replication these mutations are restricted by three overlapping error-avoidance mechanisms: the nucleotide selectivity of replicative polymerases, their proofreading activity, and mismatch repair. Using lys2InsEA14 , a frameshift reporter that is poorly proofread, we show that rereplication induces up to a 30× higher rate of frameshift mutations and that this mutagenesis is due to passage of the rereplication fork, not secondary to rereplication fork breakage. Rereplication can also induce comparable rates of frameshift and base-substitution mutations in a more general mutagenesis reporter CAN1, when the proofreading activity of DNA polymerase ε is inactivated. Finally, we show that the rereplication-induced mutagenesis of both lys2InsEA14 and CAN1 disappears in the absence of mismatch repair. These results suggest that mismatch repair is attenuated during rereplication, although at most sequences DNA polymerase proofreading provides enough error correction to mitigate the mutagenic consequences. Thus, rereplication can facilitate nucleotide-level mutagenesis in addition to inducing gross chromosomal alterations, broadening its potential role in genome instability.
| S-EPMC6553831 | biostudies-literature
Project description:Aneuploidy, a hallmark of cancer, often arises from whole chromosome instability (W-CIN). Many cancers exhibiting W-CIN, however, show no direct insult to the mitotic proteins that ensure proper segregation of chromosomes. This has stimulated interest in identifying defects in non-mitotic processes that might disrupt chromosome behavior in mitosis. Here we show in Saccharomyces cerevisiae that re-replication of centromeric DNA, caused by deregulation of replication initiation proteins, efficiently induces chromosome instability––either by causing missegregation of both sister chromatids to one daughter cell or by triggering formation of an extra chromatid through a pathway dependent on homologous recombination. Given the emerging connections between the deregulation of replication initiation proteins and oncogenesis, our findings offer the possibility of a new non-mitotic source of W-CIN and aneuploidy that may be relevant to cancer. Diploid strains containing a re-replicating locus were induced to re-replicate through a centromere. This compilation includes the analysis of the re-replication, as well as the copy-number determination of alleged aneuploid colonies from various backgrounds. Series contains a total of 194 copy number hybridizations and 8 re-replication profile hybridizations. Note that the VALUE field reported for all of the sample tables in this series are the log2 of the normalized Cy3/Cy5 ratio. To convert these into usable copy number profiles raise 2 to the indicated VALUE.
2014-07-25 | E-GEOD-55641 | biostudies-arrayexpress
Project description:To maintain genomic stability, re-initiation of eukaryotic DNA replication within a single cell cycle is blocked by multiple mechanisms that inactivate or remove replication proteins after G1 phase. Consistent with the prevailing notion that these mechanisms are redundant, we previously showed that simultaneous deregulation of three replication proteins, ORC, Cdc6 and Mcm2-7, was necessary to cause detectable bulk re-replication in G2/M phase in Saccharomyces cerevisiae. In this study, we used microarray comparative genomic hybridization (CGH) to provide a more comprehensive and detailed analysis of re-replication. This genome-wide analysis suggests that re-initiation in G2/M phase primarily occurs at a subset of both active and latent origins, but is independent of chromosomal determinants that specify the use and timing of these origins in S phase. We demonstrate that re-replication can be induced within S phase, but differs in amount and location fr om re-replication in G2/M phase, illustrating the dynamic nature of DNA replication controls. Finally, we show that very limited re-replication can be detected by microarray CGH when only two replication proteins are deregulated, suggesting that the mechanisms blocking re-replication are not redundant. Therefore we propose that eukaryotic re-replication at levels below current detection limits may be more prevalent and a greater source of genomic instability than previously appreciated. Keywords: comparative genomic hybridization (CGH), DNA replication, re-replication
2006-03-17 | GSE4181 | GEO
Project description:DNA replication must be tightly controlled during each cell cycle to prevent unscheduled replication and ensure proper genome maintenance. The currently known controls that prevent re-replication act redundantly to inhibit pre-Replicative Complex (pre-RC) assembly outside of the G1 phase of the cell cycle. We have analyzed the effects of re-replication on the S. cerevisiae genome using a combination of Comparitive Genomic Hybridization (CGH) of re-replicating strains and Genome-Wide Location Analysis of pre-RC components. These data indicate which sites in the genome assemble pre-RCs under re-replication conditions, which sites undergo re-initiation and the extent of re-replication. Keywords: comparative genomic hybridization, ChIP-chip, re-replication, DNA replication, pre-RC
2006-03-20 | GSE4487 | GEO
Project description:Eukaryotic cells must inhibit re-initiation of DNA replication at each of the thousands of origins in their genome because re-initiation can generate genomic alterations with extraordinary frequency. To minimize the probability of re-initiation from so many origins, cells use a battery of regulatory mechanisms that reduce the activity of replication initiation proteins. Given the global nature of these mechanisms, it has been presumed that all origins are inhibited identically. However, origins re-initiate with diverse efficiencies when these mechanisms are disabled, and this diversity cannot be explained by differences in the efficiency or timing of origin initiation during normal S phase replication. This observation raises the possibility of an additional layer of replication control that can differentially regulate re-initiation at distinct origins. We have identified novel genetic elements that are necessary for preferential re-initiation of two origins and sufficient to confer preferential re-initiation on heterologous origins when the control of re-initiation is partially deregulated. The elements do not enhance the S phase timing or efficiency of adjacent origins and thus are specifically acting as re-initiation promoters (RIPs). We have mapped the two RIPs to ~60 bp AT rich sequences that act in a distance- and sequence-dependent manner. During the induction of re-replication, Mcm2-7 reassociates both with origins that preferentially re-initiate and origins that do not, suggesting that the RIP elements can overcome a block to re-initiation imposed after Mcm2-7 associates with origins. Our findings identify a local level of control in the block to re-initiation. This local control creates a complex genomic landscape of re-replication potential that is revealed when global mechanisms preventing re-replication are compromised. Hence, if re-replication does contribute to genomic alterations, as has been speculated for cancer cells, some regions of the genome may be more susceptible to these alterations than others.
2014-03-15 | GSE55420 | GEO
Project description:Purpose: Next-generation sequencing (NGS) has revolutionized systems-based analysis of cellular pathways. The goals of this study are to compare NGS-derived transcriptome profiling (RNA-seq) and transposon insertion mutagenesis (Tnseq) libraries of Lon deletions compared to wt Caulobacter crescentus. Methods: See Methods section of The Lon protease links nucleotide metabolism with proteotoxic stress for information regarding methods or contact lead correspondence. Briefly, Samples for RNAseq were extracted from wt and lon deletion strains grown to mid exponential phase. Methods: See Methods section of The Lon protease links nucleotide metabolism with proteotoxic stress for information regarding methods or contact lead correspondence. Briefly, Samples for Tnseq were generated by Eztn5 transposon mutagenesis. Conclusions: Our study represents the first detailed analysis of lon deletion comparison to wt caulobacter transcriptomes, with biologic replicates, generated by RNA-seq technology.
2020-06-14 | GSE152426 | GEO
Project description:Nucleotide level linkage of transcriptional elongation and polyadenylation
| PRJNA883942 | ENA
Project description:The relationship between epigenetic marks on chromatin and the regulation of DNA replication is poorly understood. Mutation of the H3K27 methyltransferase genes, ARABIDOPSIS TRITHORAX-RELATED PROTEIN5 (ATXR5) and ATXR6, result in re-replication (repeated origin firing within the same cell cycle). Here we show that mutations that reduce DNA methylation act to suppress the re-replication phenotype of atxr5 atxr6 mutants. This suggests that DNA methylation, a mark enriched at the same heterochromatic regions that re-replicate in atxr5/6 mutants, is required for aberrant re-replication. In contrast, RNA sequencing analyses suggest that ATXR5/6 and DNA methylation cooperatively transcriptionally silence transposable elements (TEs). Hence our results suggest a complex relationship between ATXR5/6 and DNA methylation in the regulation of DNA replication and transcription of TEs.
2012-08-07 | GSE38286 | GEO
Project description:The relationship between epigenetic marks on chromatin and the regulation of DNA replication is poorly understood. Mutation of the H3K27 methyltransferase genes, ARABIDOPSIS TRITHORAX-RELATED PROTEIN5 (ATXR5) and ATXR6, result in re-replication (repeated origin firing within the same cell cycle). Here we show that mutations that reduce DNA methylation act to suppress the re-replication phenotype of atxr5 atxr6 mutants. This suggests that DNA methylation, a mark enriched at the same heterochromatic regions that re-replicate in atxr5/6 mutants, is required for aberrant re-replication. In contrast, RNA sequencing analyses suggest that ATXR5/6 and DNA methylation cooperatively transcriptionally silence transposable elements (TEs). Hence our results suggest a complex relationship between ATXR5/6 and DNA methylation in the regulation of DNA replication and transcription of TEs. DNA-seq: One gram of mature rosette leaves were collected from 3-4-week-old plants, chopped in 0.5 ml of filtered Galbraith buffer, and stained with propidium iodide. A BD FACS Aria II in the UCLA Jonsson Comprehensive Cancer Center (JCCC) Flow Cytometry Core Facility was used to sort the nuclei. For sequencing, 7,000-9,000 8C nuclei of each sample were collected, and purified DNA with Picopure purification kit (Arcturus) following manufacturer instructions. RNA-seq: RNA-seq experiments were performed in two biological replicates for each genotype. 0.1g of tissue was ground in Trizol. Total RNA were treated with DNaseI (Roche), and cleaned up with phenol-chlorophorm and precipitated with ethanol. Libraries were generated and sequenced following manufacturer instructions (Illumina). BS-seq: 0.5-1g of mature rosette leaves were collected, and genomic DNA was extracted using Plant DNeasey mini purification kit (Qiagen). Libraries were generated as previously described (Feng et al., Methods Mol Biol. 2011;733:223-38.).
2012-08-07 | E-GEOD-38286 | biostudies-arrayexpress