Caenorhabditis elegans
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ABSTRACT:
OTHER RELATED OMICS DATASETS IN: E-GEOD-21467
PROVIDER: PRJNA125817 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:The nematode Caenorhabditis elegans has been used extensively to study responses to DNA damage. In contrast, little is known about DNA repair in this organism. C. elegans is unusual in that it encodes few DNA glycosylases and the uracil-DNA glycosylase (UDG) encoded by the ung-1 gene is the only known UDG. C. elegans could therefore become a valuable model organism for studies of the genetic interaction networks involving base excision repair (BER). As a first step towards characterization of BER in C. elegans, we show that the UNG-1 protein is an active uracil-DNA glycosylase. We demonstrate that an ung-1 mutant has reduced ability to repair uracil-containing DNA but that an alternative Ugi-inhibited activity is present in ung-1 nuclear extracts. Finally, we demonstrate that ung-1 mutants show altered levels of apoptotic cell corpses formed in response to DNA damaging agents. Increased apoptosis in the ung-1 mutant in response to ionizing radiation (IR) suggests that UNG-1 contributes to repair of IR-induced DNA base damage in vivo. Following treatment with paraquat however, the apoptotic corpse-formation was reduced. Gene expression profiling suggests that this phenotype is a consequence of compensatory transcriptomic shifts that modulate oxidative stress responses in the mutant and not an effect of reduced DNA damage signaling.
2010-05-26 | GSE21467 | GEO
Project description:The nematode Caenorhabditis elegans has been used extensively to study responses to DNA damage. In contrast, little is known about DNA repair in this organism. C. elegans is unusual in that it encodes few DNA glycosylases and the uracil-DNA glycosylase (UDG) encoded by the ung-1 gene is the only known UDG. C. elegans could therefore become a valuable model organism for studies of the genetic interaction networks involving base excision repair (BER). As a first step towards characterization of BER in C. elegans, we show that the UNG-1 protein is an active uracil-DNA glycosylase. We demonstrate that an ung-1 mutant has reduced ability to repair uracil-containing DNA but that an alternative Ugi-inhibited activity is present in ung-1 nuclear extracts. Finally, we demonstrate that ung-1 mutants show altered levels of apoptotic cell corpses formed in response to DNA damaging agents. Increased apoptosis in the ung-1 mutant in response to ionizing radiation (IR) suggests that UNG-1 contributes to repair of IR-induced DNA base damage in vivo. Following treatment with paraquat however, the apoptotic corpse-formation was reduced. Gene expression profiling suggests that this phenotype is a consequence of compensatory transcriptomic shifts that modulate oxidative stress responses in the mutant and not an effect of reduced DNA damage signaling. C. elegans RNAi mutants deficient in ung-1 and the corresponding wild-type N2, were subjected to Affymetrix whole C. elegans genome microarrays. Triplicates were run for each sample group.
2010-06-08 | E-GEOD-21467 | biostudies-arrayexpress
Project description:DNA base lesions, such as incorporation of uracil into DNA or base mismatches, can be mutagenic and toxic to replicating cells. To discover factors in repair of genomic uracil, we performed a CRISPR knockout screen in the presence of floxuridine, a chemotherapeutic agent that incorporates uracil and fluoro-uracil into DNA. We identified known factors, such as uracil DNA N-glycosylase (UNG), but also unknown factors, such as the N6-adenosine methyltransferase, METTL3, as required to overcome floxuridine-driven cytotoxicity. Visualized with immunofluorescence, the product of METTL3 activity, N6-methyladenosine, formed nuclear foci in cells treated with floxuridine. The observed N6-methyladenosine was embedded in DNA, called 6mA, which was confirmed using mass spectrometry. METTL3 and 6mA were required for repair of lesions driven by additional base damaging agents, including raltitrexed, gemcitabine, and hydroxyurea. Our results establish a role for METTL3 and 6mA to promote genome stability in mammalian cells, specially in response to base damage.
2024-11-22 | GSE282260 | GEO
Project description:To test the effects of uracil DNA glycosylase (UNG) loss on the formation of double strand breaks (DSBs) by the anti-cancer agent pemetrexed, we performed ChIP-seq for serine 139-phosphorylated H2AX (gammaH2AX), a marker of DSBs, in human cells wild-type or deficient for UNG in combination with pemetrexed treatment. UNG deficiency results in an increase in DSBs upon pemetrexed treatment, and we found that pemetrexed treatment induces DSBs at different genomic locations in UNG wild-type and knockout cells. Similar results were observed upon cisplatin treatment of UNG wild-type and knockout cells, and the genomic locations of DSBs were distinct between pemetrexed-treated and cisplatin-treated samples. Taken together, our results suggest differential mechanisms for DSB formation in UNG-competent and UNG-deficient cells.
2013-10-28 | GSE50692 | GEO
Project description:To test the effects of uracil DNA glycosylase (UNG) loss on the formation of double strand breaks (DSBs) by the anti-cancer agent pemetrexed, we performed ChIP-seq for serine 139-phosphorylated H2AX (gammaH2AX), a marker of DSBs, in human cells wild-type or deficient for UNG in combination with pemetrexed treatment. UNG deficiency results in an increase in DSBs upon pemetrexed treatment, and we found that pemetrexed treatment induces DSBs at different genomic locations in UNG wild-type and knockout cells. Similar results were observed upon cisplatin treatment of UNG wild-type and knockout cells, and the genomic locations of DSBs were distinct between pemetrexed-treated and cisplatin-treated samples. Taken together, our results suggst differential mechanisms for DSB formation in UNG-competent and UNG-deficient cells. The genomic distribution of gammaH2AX in UNG WT and KO cells treated with pemetrexed or cisplatin was determined by ChIP-seq
2013-10-28 | E-GEOD-50692 | biostudies-arrayexpress
Project description:We report a new immunoprecipitation-coupled sequencing (DIP-Seq) application termed U-DNA-Seq, where a tailored and catalytically inactive uracil-DNA glycosylase (UNG) was used as uracil-DNA sensor to immunoprecipitate uracil containing genomic DNA fragments. Genomic uracil was profiled in drug-treated (5-fluoro-2'-deoxyuridine (5FdUR) or raltitrexed (RTX)) or non-treated (NT) HCT116 cells expressing the UNG inhibitor (UGI). The same experiments were also performed in the mismatch repair proficient version of the HCT116 cells (HCT116MMR), where chromosome 3 is reinserted to restore functional MMR (PMID: 8044777). Moreover, wild-type HCT116 or K562 cells were also measured. We found that regions of uracil enrichment in this assay were rather broad as compared to the sharp peaks typical in ChIP-seq. Therefore, we applied an approach alternative to the conventional peak calling. Namely, we calculated genome scaled coverage tracks and log2 ratio tracks of the enriched versus the input samples using deepTools package (bamCoverage and bigwigCompare tools, respectively) to provide a more appropriate description of uracil-enriched genomic regions. Interval (bed) files were also derived from these log2 ratio tracks to be able to screen large datasets for colocalizing features with them. For wider context of the study, see the related publication.
2020-09-20 | GSE126822 | GEO
Project description:The cytotoxic mechanisms of thymidylate synthase inhibitors, such as the multitarget antifolate pemetrexed, are not yet fully understood. Emerging evidence indicates that combining pemetrexed with histone deacetylase inhibitors (HDACi) may enhance therapeutic efficacy in non-small cell lung cancer (NSCLC). To explore this further, A549 NSCLC cells were treated with various combinations of pemetrexed and the HDACi MS275 (Entinostat), and subsequently assessed for cell viability, cell cycle changes, and genotoxic markers. Proteomic alterations were analyzed using label-free shotgun and targeted LC–MS/MS. MS275 enhanced the sensitivity of A549 cells to pemetrexed, but only when administered following prior treatment with pemetrexed. Both HeLa (p53 negative) and A549 (p53 positive) showed robust activation of γH2AX upon treatment with this combination. Importantly, CRISPR/Cas9 knockout of the uracil-DNA glycosylase UNG did not affect γH2AX activation or sensitivity to pemetrexed. Proteomic analysis revealed that MS275 altered the expression of known pemetrexed targets, as well as several proteins involved in pyrimidine metabolism and DNA repair, which could potentiate pemetrexed cytotoxicity. Contrary to the conventional model of antifolate toxicity, which implicates futile cycles of uracil incorporation and excision in DNA, we propose that ribonucleotide incorporation in nuclear and mitochondrial DNA significantly contributes to the cytotoxicity of antifolates like pemetrexed, and likely also of fluorinated pyrimidine analogs. HDAC inhibition apparently exacerbates cytotoxicity of these agents by inhibiting error-free repair of misincorporated ribonucleotides in DNA. The potential of HDACis to modulate pyrimidine metabolism and DNA damage responses offers novel strategies for improving NSCLC outcomes.
2024-12-18 | PXD051824 | Pride
Project description:Secondary diversification of antibodies through somatic hypermutation (SHM) and class switch recombination (CSR) is a critical component of the immune response. Activation-induced deaminase (AID) initiates both processes by deaminating cytosine residues in immunoglobulin genes. The resulting U:G mismatch can be processed by alternative pathways to give rise to a mutation (SHM) or a DNA double-strand break (CSR). Central to this processing is the activity of uracil-N-glycosylase (UNG), an enzyme normally involved in error-free base excision repair. We used next generation sequencing to analyze the contribution of UNG to the resolution of AID-induced lesions. Loss- and gain-of-function experiments showed that UNG activity can promote both error-prone and high fidelity repair of U:G lesions. Unexpectedly, the balance between these alternative outcomes was influenced by the sequence context of the deaminated cytosine, with individual hotspots exhibiting higher susceptibility to UNG-triggered error-free or error-prone resolution. These results reveal UNG as a new molecular layer that shapes the specificity of AID-induced mutations and may provide new insights into the role of AID in cancer development.
2012-07-05 | GSE39108 | GEO
Project description:Secondary diversification of antibodies through somatic hypermutation (SHM) and class switch recombination (CSR) is a critical component of the immune response. Activation-induced deaminase (AID) initiates both processes by deaminating cytosine residues in immunoglobulin genes. The resulting U:G mismatch can be processed by alternative pathways to give rise to a mutation (SHM) or a DNA double-strand break (CSR). Central to this processing is the activity of uracil-N-glycosylase (UNG), an enzyme normally involved in error-free base excision repair. We used next generation sequencing to analyze the contribution of UNG to the resolution of AID-induced lesions. Loss- and gain-of-function experiments showed that UNG activity can promote both error-prone and high fidelity repair of U:G lesions. Unexpectedly, the balance between these alternative outcomes was influenced by the sequence context of the deaminated cytosine, with individual hotspots exhibiting higher susceptibility to UNG-triggered error-free or error-prone resolution. These results reveal UNG as a new molecular layer that shapes the specificity of AID-induced mutations and may provide new insights into the role of AID in cancer development.
2012-07-05 | GSE39114 | GEO
Project description:Secondary diversification of antibodies through somatic hypermutation (SHM) and class switch recombination (CSR) is a critical component of the immune response. Activation-induced deaminase (AID) initiates both processes by deaminating cytosine residues in immunoglobulin genes. The resulting U:G mismatch can be processed by alternative pathways to give rise to a mutation (SHM) or a DNA double-strand break (CSR). Central to this processing is the activity of uracil-N-glycosylase (UNG), an enzyme normally involved in error-free base excision repair. We used next generation sequencing to analyze the contribution of UNG to the resolution of AID-induced lesions. Loss- and gain-of-function experiments showed that UNG activity can promote both error-prone and high fidelity repair of U:G lesions. Unexpectedly, the balance between these alternative outcomes was influenced by the sequence context of the deaminated cytosine, with individual hotspots exhibiting higher susceptibility to UNG-triggered error-free or error-prone resolution. These results reveal UNG as a new molecular layer that shapes the specificity of AID-induced mutations and may provide new insights into the role of AID in cancer development. Next Generation Sequencing analysis of mutations introduced by AID in activated B lymphocytes from WT and UNG-/- mice (n=4). Activated B cells from AID-/- mice (n=2) were used as negative controls.
2012-07-04 | E-GEOD-39114 | biostudies-arrayexpress