Saccharomyces cerevisiae
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ABSTRACT:
PROVIDER: PRJNA176386 | ENA |
REPOSITORIES: ENA
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Project description:Copy number expansions such as amplifications and duplications contribute to human phenotypic variation, promote molecular diversification during evolution, and drive the initiation and/or progression of various cancers. The mechanisms underlying these copy number changes are still incompletely understood, however. We recently demonstrated that transient, limited re-replication from a single origin in Saccharomyces cerevisiae efficiently induces segmental amplification of the re-replicated region. Structural analyses of such re-replication induced gene amplifications (RRIGA) suggested that RRIGA could provide a new mechanism for generating copy number variation by non-allelic homologous recombination (NAHR). Here we elucidate this new mechanism and provide insight into why it is so efficient. We establish that sequence homology is both necessary and sufficient for repetitive elements to participate in RRIGA and show that their recombination occurs by a single-strand annealing (SSA) mechanism. We also find that re-replication forks are prone to breakage, accounting for the widespread DNA damage associated with deregulation of replication proteins. These breaks appear to stimulate NAHR between re-replicated repeat sequences flanking a re-initiating replication origin. Our results support a RRIGA model where the expansion of a re-replication bubble beyond flanking homologous sequences followed by breakage at both forks in trans provides an ideal structural context for SSA–mediated NAHR to form a head-to-tail duplication. Given the remarkable efficiency of RRIGA, we suggest it may be an unappreciated contributor to copy number expansions in both disease and evolution.
2013-01-04 | GSE41259 | GEO
Project description:Copy number expansions such as amplifications and duplications contribute to human phenotypic variation, promote molecular diversification during evolution, and drive the initiation and/or progression of various cancers. The mechanisms underlying these copy number changes are still incompletely understood, however. We recently demonstrated that transient, limited re-replication from a single origin in Saccharomyces cerevisiae efficiently induces segmental amplification of the re-replicated region. Structural analyses of such re-replication induced gene amplifications (RRIGA) suggested that RRIGA could provide a new mechanism for generating copy number variation by non-allelic homologous recombination (NAHR). Here we elucidate this new mechanism and provide insight into why it is so efficient. We establish that sequence homology is both necessary and sufficient for repetitive elements to participate in RRIGA and show that their recombination occurs by a single-strand annealing (SSA) mechanism. We also find that re-replication forks are prone to breakage, accounting for the widespread DNA damage associated with deregulation of replication proteins. These breaks appear to stimulate NAHR between re-replicated repeat sequences flanking a re-initiating replication origin. Our results support a RRIGA model where the expansion of a re-replication bubble beyond flanking homologous sequences followed by breakage at both forks in trans provides an ideal structural context for SSA–mediated NAHR to form a head-to-tail duplication. Given the remarkable efficiency of RRIGA, we suggest it may be an unappreciated contributor to copy number expansions in both disease and evolution. The arrays in this series are primary comparative genomic hybridizations to determine genomic changes after re-replication. Genomic DNA was purified from reference Saccharomyces cerevisiae cells or survivors of re-replication, differentially labeled with Cy3 and Cy5, and competitively hybridized to a spotted microarray containing ORF and intergenic PCR products. Cy5/Cy3 ratios (or the inverse in the case of dye swapped samples) are normalized so that the average ratio of all elements was 1 (except for arrays measuring re-replication induction where this ratio was set to 2). A small number of the arrays were used to determine the extent and location of re-replication under different conditions. For those, genomic DNA was purified from non-replicating and re-replicating cells and treated as above. Series contains a total of 333 hybridizations. Note that the VALUE field reported for all of the sample tables in this series are the log2 of the normalized Cy5/Cy3 (or Cy3/Cy5) ratio. To convert these into usable copy number profiles raise 2 to the indicated VALUE.
2013-01-04 | E-GEOD-41259 | biostudies-arrayexpress
Project description:DNA replication initiates at defined sites called origins, which serve as binding sites for initiator proteins that recruit the replicative machinery. Origins differ in number and structure across the three domains of life1 and their properties determine the dynamics of chromosome replication. Bacteria and some archaea replicate from single origins, whilst most archaea and all eukaryotes replicate using multiple origins. Initiation mechanisms that rely on homologous recombination operate in some viruses. Here we show that such mechanisms also operate in archaea. We have used deep sequencing to study replication in Haloferax volcanii. Four chromosomal origins of differing activity were identified. Deletion of individual origins resulted in perturbed replication dynamics and reduced growth. However, a strain lacking all origins has no apparent defects and grows significantly faster than wild-type. Origin-less cells initiate replication at dispersed sites rather than at discrete origins and have an absolute requirement for the recombinase RadA, unlike strains lacking individual origins. Our results demonstrate that homologous recombination alone can efficiently initiate the replication of an entire cellular genome. This raises the question of what purpose replication origins serve and why they have evolved. Measurement of replication dynamics (marker frequency analysis; MFA) for Haloferax volcanii strains, including wild-type, the laboratory strain, individual and combinations of replication origin deletions.
2013-11-03 | E-GEOD-41961 | biostudies-arrayexpress
Project description:DNA replication initiates at defined sites called origins, which serve as binding sites for initiator proteins that recruit the replicative machinery. Origins differ in number and structure across the three domains of life1 and their properties determine the dynamics of chromosome replication. Bacteria and some archaea replicate from single origins, whilst most archaea and all eukaryotes replicate using multiple origins. Initiation mechanisms that rely on homologous recombination operate in some viruses. Here we show that such mechanisms also operate in archaea. We have used deep sequencing to study replication in Haloferax volcanii. Four chromosomal origins of differing activity were identified. Deletion of individual origins resulted in perturbed replication dynamics and reduced growth. However, a strain lacking all origins has no apparent defects and grows significantly faster than wild-type. Origin-less cells initiate replication at dispersed sites rather than at discrete origins and have an absolute requirement for the recombinase RadA, unlike strains lacking individual origins. Our results demonstrate that homologous recombination alone can efficiently initiate the replication of an entire cellular genome. This raises the question of what purpose replication origins serve and why they have evolved.
2013-11-03 | GSE41961 | GEO
Project description:Somatic non-allelic homologous recombination caused by repeat elements
| PRJNA636606 | ENA
Project description:The DNA double-strand breaks that initiate homologous recombination during meiosis are subject to extensive 5ʹâ??3â?² exonucleolytic processing. This resection is a central and conserved feature of recombination, yet its mechanism is poorly understood. Using a purpose-made deep-sequencing method, namely S1Seq, we mapped meiotic resection endpoints genome-wide at high spatial resolution in Saccharomyces cerevisiae. Generating full-length resection tracts requires Exo1 exonuclease activity and the DNA-damage responsive kinase Tel1, but not the helicase Sgs1. Tel1 is also required for efficient and timely initiation of resection. We find that distributions of resection endpoints at individual genomic loci display pronounced heterogeneity that reflects a tendency for nucleosomes to block Exo1 in vivo, yet modeling experiments indicate that Exo1 digests chromatin with high apparent processivity and at rates approaching those for naked DNA in vitro. This paradox points to nucleosome destabilization or eviction as a determining feature of the meiotic resection landscape. 36 samples total: two biological replicate S1Seq maps of S.cerevisiae for each genetic background and time point in meiosis
2016-08-06 | E-GEOD-85253 | biostudies-arrayexpress
Project description:HS-10502 is a Poly(ADP-ribose) polymerase 1 (PARP1)-specific selective inhibitor. The purpose if this study is to assess the safety, tolerability, pharmacokinetics (PK), and efficacy of HS-10502 in subjects with homologous recombination repair (HRR) gene mutant or homologous recombination deficiency (HRD) positive advanced solid tumors.
| 9330 | ecrin-mdr-crc
Project description:Homologous recombination (HR) serves multiple roles in DNA repair that are essential for maintaining genomic stability. The central HR protein, RAD51, is frequently overexpressed in human malignancies, thereby elevating HR proficiency and promoting resistance to DNA-damaging therapies. Here we find that non-canonical NF-κB factors control the expression of RAD51 andother HR-promoting proteins. Transcriptional silencing of p100/p52 reduces RAD51 protein levels in multiple human cancer subtypes. RNA-seq after p100/p52 silencing identifies RAD51 as the most differentially expressed gene among 40 genes with known relevance to HR. While p100/p52 depletion inhibits HR function in human tumor cells, it does not influence the function of other double-strand DNA repair pathways including single-strand annealing, microhomology mediated annealing, or non-homologous end joining.
2022-06-07 | GSE148511 | GEO
Project description:53BP1 governs a specialized, context-specific branch of the classical non-homologous end joining DNA double-strand break repair pathway. Mice lacking 53bp1 (also known as Trp53bp1) are immunodeficient owing to a complete loss of immunoglobulin class-switch recombination, and reduced fidelity of long-range V(D)J recombination. The 53BP1-dependent pathway is also responsible for pathological joining events at dysfunctional telomeres, and its unrestricted activity in Brca1-deficient cellular and tumour models causes genomic instability and oncogenesis. Cells that lack core non-homologous end joining proteins are profoundly radiosensitive, unlike 53BP1-deficient cells, which suggests that 53BP1 and its co-factors act on specific DNA substrates. Here we show that 53BP1 cooperates with its downstream effector protein REV7 to promote non-homologous end joining during class-switch recombination, but REV7 is not required for 53BP1-dependent V(D)J recombination. We identify shieldin—a four-subunit putative single-stranded DNA-binding complex comprising REV7, c20orf196 (SHLD1), FAM35A (SHLD2) and FLJ26957 (SHLD3)— as the factor that explains this specificity. Shieldin is essential for REV7-dependent DNA end-protection and non-homologous end joining during class-switch recombination, and supports toxic non-homologous end joining in Brca1-deficient cells, yet is dispensable for REV7-dependent interstrand cross-link repair. The 53BP1 pathway therefore comprises distinct double-strand break repair activities within chromatin and single-stranded DNA compartments, which explains both the immunological differences between 53bp1- and Rev7- deficient mice and the context specificity of the pathway.
2018-07-26 | PXD009650 | Pride
Project description:The DNA double-strand breaks that initiate homologous recombination during meiosis are subject to extensive 5ʹ→3′ exonucleolytic processing. This resection is a central and conserved feature of recombination, yet its mechanism is poorly understood. Using a purpose-made deep-sequencing method, namely S1Seq, we mapped meiotic resection endpoints genome-wide at high spatial resolution in Saccharomyces cerevisiae. Generating full-length resection tracts requires Exo1 exonuclease activity and the DNA-damage responsive kinase Tel1, but not the helicase Sgs1. Tel1 is also required for efficient and timely initiation of resection. We find that distributions of resection endpoints at individual genomic loci display pronounced heterogeneity that reflects a tendency for nucleosomes to block Exo1 in vivo, yet modeling experiments indicate that Exo1 digests chromatin with high apparent processivity and at rates approaching those for naked DNA in vitro. This paradox points to nucleosome destabilization or eviction as a determining feature of the meiotic resection landscape.
2016-08-06 | GSE85253 | GEO