CGH of stage 13 amplifying follicle cells to measure changes in replication fork progression in DNA damage checkpoint and double-strand break repair mutants
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE66690 | GEO | 2015/06/18
SECONDARY ACCESSION(S): PRJNA277728
REPOSITORIES: GEO
Similar Datasets
Project description:CGH of stage 13 amplifying follicle cells to measure changes in replication fork progression in double-strand break repair mutants Comparative genomic hybridization was performed to compare amplification gradients of stage 13 follicle cells from several double-strand break repair mutants to wild type (OrR) gradients. Two-three replicates were done for each genotype.
2017-02-08 | GSE86012 | GEO
Project description:Comparative genomic hybridization was performed to compare amplificaiton gradients in genomic DNA derived from stage 13 egg chambers of wild-type, suppressor of under-replication (SuUR) mutant and SuUR overexpression, compared with 0-2hr diploid embryo gDNA. Comparative genomic hybridization was performed to compare amplificaiton gradients in genomic DNA derived from stage 10B egg chambers of wild-type, compared with 0-2hr diploid embryo gDNA.
2014-11-10 | GSE56054 | GEO
Project description:We analyzed gamaH2Av ChIP-seq from hand dissected stage 10B and 13 follicle cell nuclei. Egg chambers were dissected from wild-type (OrR) or H2Av[ΔCT] ovaries to assess binding at the Drosophila Follicle Cell Amplicons and across the genome. ChIP-seq of gammaH2Av bound to follicle cell DNA from stage 10B and 13 egg chambers, collected from wild-type (OrR) and H2Av[ΔCT] Drosophila ovaries. Sequences analyzed by Illumina sequencing. Two replicates are included for each ChIP reaction.
2015-06-18 | E-GEOD-66689 | biostudies-arrayexpress
Project description:modENCODE_submission_724 This submission comes from a modENCODE project of David MacAlpine. For full list of modENCODE projects, see http://www.genome.gov/26524648 Project Goal: Most terminally differentiated Drosophila tissues are either polyploid or polytene. Unlike normal chromosomes, where the entire chromosome must be replicated exactly once, polytene chromosomes are often differentially replicated with many regions underreplicated and some overreplicated. We will characterize five different polytene tissues using comparative genomic hybridization (CGH) to identify differentially replicated regions of each chromosome. These studies will also identify tissue specific amplicons, where the replication mediated amplification of specific loci is essential for up-regulation of mRNA levels encoding proteins critical for development. The differential replication of polytene chromosomes in Drosophila will provide a unique opportunity to understand how developmental cues and chromosomal domains influence replication initiation. Keywords: CGH For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf EXPERIMENT TYPE: CGH. BIOLOGICAL SOURCE 1: Strain: Oregon-R Orr-Weaver; Tissue: oocyte associated follicle cell; Genotype: TBA; Sex: Female; BIOLOGICAL SOURCE 2: Strain: Oregon-R Orr-Weaver; Developmental Stage: Embryo 0-4h; Genotype: TBA; Sex: Unknown; NUMBER OF REPLICATES: 1; EXPERIMENTAL FACTORS: Tissue oocyte associated follicle cell
2010-05-15 | E-GEOD-17291 | biostudies-arrayexpress
Project description:We analyzed gamaH2Av ChIP-seq from hand dissected stage 10B and 13 follicle cell nuclei. Egg chambers were dissected from wild-type (OrR) or H2Av[ΔCT] ovaries to assess binding at the Drosophila Follicle Cell Amplicons and across the genome.
2015-06-18 | GSE66689 | GEO
Project description:In response to replication stress, the Mec1/ATR and SUMO pathways control stalled- and damaged-fork stability. We investigated the S phase response at forks encountering a broken template (termed the terminal fork). We show that double-strand break (DSB) formation can locally trigger dormant origin firing. Irreversible fork resolution at the break does not impede progression of the other fork in the same replicon (termed the sister fork). The Mre11-Tel1/ATM response acts at terminal forks, preventing accumulation of cruciform DNA intermediates that tether sister chromatids and can undergo nucleolytic processing. We conclude that sister forks can be uncoupled during replication and that, after DSB-induced fork termination, replication is rescued by dormant origin firing or adjacent replicons. We have uncovered a Tel1/ATM- and Mre11-dependent response controlling terminal fork integrity. Our findings have implications for those genome instability syndromes that accumulate DNA breaks during S phase and for forks encountering eroding telomeres.
| S-EPMC2789576 | biostudies-literature
Project description:Telomerase-independent ALT (alternative lengthening of telomeres) cells are characterized by high frequency of telomeric homologous recombination (HR), C-rich extrachromosomal circles (C-circles) and C-rich terminal 5' overhangs (C-overhangs). However, underlying mechanism is poorly understood. Here, we show that both C-circle and C-overhang form when replication fork collapse is induced by strand break at telomeres. We find that endogenous DNA break predominantly occur on C-rich strand of telomeres in ALT cells, resulting in high frequency of replication fork collapse. While collapsed forks could be rescued by replication fork regression leading to telomeric homologous recombination, those unresolved are converted to C-circles and C-overhang at lagging and leading synthesized strand, respectively. Meanwhile, multiple hallmarks of ALT are provoked, suggesting that strand break-induced replication stress underlies ALT. These findings provide a molecular basis underlying telomeric HR and biogenesis of C-circle and C-overhang, thus implicating the specific mechanism to resolve strand break-induced replication defect at telomeres in ALT cells.
| S-EPMC6382176 | biostudies-literature
Project description:Breast cancer suppressor BRCA2 is critical for maintenance of genomic integrity and resistance to agents that damage DNA or collapse replication forks, presumably through homology-directed repair of double-strand breaks (HDR). Using single-molecule DNA fiber analysis, we show here that nascent replication tracts created before fork stalling with hydroxyurea are degraded in the absence of BRCA2 but are stable in wild-type cells. BRCA2 mutational analysis reveals that a conserved C-terminal site involved in stabilizing RAD51 filaments, but not in loading RAD51 onto DNA, is essential for this fork protection but dispensable for HDR. RAD51 filament disruption in wild-type cells phenocopies BRCA2 deficiency. BRCA2 prevents chromosomal aberrations on replication stalling, which are alleviated by inhibition of MRE11, the nuclease responsible for this form of fork instability. Thus, BRCA2 prevents rather than repairs nucleolytic lesions at stalled replication forks to maintain genomic integrity and hence likely suppresses tumorigenesis through this replication-specific function.
| S-EPMC3261725 | biostudies-literature
Project description:Replication origins are under tight regulation to ensure activation occurs only once per cell cycle [1, 2]. Origin re-firing in a single S phase leads to the generation of DNA double-strand breaks (DSBs) and activation of the DNA damage checkpoint [2-7]. If the checkpoint is blocked, cells enter mitosis with partially re-replicated DNA that generates chromosome breaks and fusions [5]. These types of chromosomal aberrations are common in numerous human cancers, suggesting that re-replication events contribute to cancer progression. It was proposed that fork instability and DSBs formed during re-replication are the result of head-to-tail collisions and collapse of adjacent replication forks [3]. However, previously studied systems lack the resolution to determine whether the observed DSBs are generated at sites of fork collisions. Here, we utilize the Drosophila ovarian follicle cells, which exhibit re-replication under precise developmental control [8-10], to model the consequences of re-replication at actively elongating forks. Re-replication occurs from specific replication origins at six genomic loci, termed Drosophila amplicons in follicle cells (DAFCs) [10-12]. Precise developmental timing of DAFC origin firing permits identification of forks at defined points after origin initiation [13, 14]. Here, we show that DAFC re-replication causes fork instability and generates DSBs at sites of potential fork collisions. Immunofluorescence and ChIP-seq demonstrate the DSB marker ?H2Av is enriched at elongating forks. Fork progression is reduced in the absence of DNA damage checkpoint components and nonhomologous end-joining (NHEJ), but not homologous recombination. NHEJ appears to continually repair forks during re-replication to maintain elongation.
| S-EPMC4580973 | biostudies-literature
Project description:Rereplication generates double-strand breaks (DSBs) at sites of fork collisions and causes genomic damage, including repeat instability and chromosomal aberrations. However, the primary mechanism used to repair rereplication DSBs varies across different experimental systems. In Drosophila follicle cells, developmentally regulated rereplication is used to amplify six genomic regions, two of which contain genes encoding eggshell proteins. We have exploited this system to test the roles of several DSB repair pathways during rereplication, using fork progression as a readout for DSB repair efficiency. Here we show that a null mutation in the microhomology-mediated end-joining (MMEJ) component, polymerase ?/mutagen-sensitive 308 (mus308), exhibits a sporadic thin eggshell phenotype and reduced chorion gene expression. Unlike other thin eggshell mutants, mus308 displays normal origin firing but reduced fork progression at two regions of rereplication. We also find that MMEJ compensates for loss of nonhomologous end joining to repair rereplication DSBs in a site-specific manner. Conversely, we show that fork progression is enhanced in the absence of both Drosophila Rad51 homologs, spindle-A and spindle-B, revealing homologous recombination is active and actually impairs fork movement during follicle cell rereplication. These results demonstrate that several DSB repair pathways are used during rereplication in the follicle cells and their contribution to productive fork progression is influenced by genomic position and repair pathway competition. Furthermore, our findings illustrate that specific rereplication DSB repair pathways can have major effects on cellular physiology, dependent upon genomic context.
| S-EPMC5137741 | biostudies-literature