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.
Project description:A SHAPE-MaP structure probing experiment was performed on 39 firefly luciferase mRNAs containing uracil, 1-methyl-psuedouracil, or 5-methoxy-uracil. For each mRNA, SHAPE-MaP includes a sample treated with 1M6 ('MOD'), a minus reagent ('NC'), and a denatured control ('DEN'). The 1M6 reagent preferenctially reacts with unpaired bases in RNA and subsequently induces mutations during the reverse transcription step of library preparation. After sequencing and alignment, the 'mutational profiles' of the 'p', 'm', and 'd' samples are used to calculate the SHAPE reactivity of each base.
Project description:Data from Excision-seq experiments to map deoxyuridine and pyrimidine dimers in S. cerevisiae and E. coli For uracil mapping in pre-digestion Excision-seq, uracil was excised from genomic DNA from dut ung yeast and bacteria yielding double-stranded DNA fragments. Adapters were ligated to these fragments for Illumina library preparation. Using this method, the number of reads at a genomic location corresponds to the quantity of dU at that location. In post-digestion Excision-seq, uracil-containing library fragments are destroyed by UDG treatment, thus coverage is inversely proportional to uracil content. For pyrimidine dimer Excision-seq, yeast were irradiated with high doses of UVC light to generate a large number of DNA modifications. Using the excision repair enzyme UVDE from S. pombe, we excised pyrimidine dimers, cutting the phosphodieseter bond to release small double stranded fragments. These fragments were repaired with either CPD photolyase or 6-4 photolyase to generate independent libraries for each modification type. Illumina adapters were ligated to these fragments for library preparation. Using this method the number of reads at a genomic location corresponds to the quantity of the 3' pyrimidine of the dimer.
Project description:HDAC inhibitors (HDACi) belong to a new group of chemotherapeutics that are increasingly used to treat B-cell-derived malignancies. Such malignancies regularly carry mutational signatures that conform to off-target induction of uracil by the AID/APOBEC family of cytidine deaminases, or downstream processing of uracil. . HDACi suppress thymidylate synthase increasing the cellular dUTP/dTTP ratio and leading to increased pressure on uracil repair machinery due to misincorporated uracil lesions. To investigate potential effect upon other enzymes involved in genomic uracil induction and processing, Jurkat (T-cell lymphoma) and SUDHL5 (B-cell lymphoma) cells were treated with pan-HDACi SAHA prior to SILAC based MS/MS investigation. HDACi treatment mediated significant differential expression of xx and xx proteins in Jurkat and SUDHL5, respectively, and had a substantial impact upon enzymes involved in in pyrimidine metabolism. Surprisingly, uracil N-glycosylase, UNG, was strongly downregulated by HDACi treatment. Further analysis in HEK and HeLa cells revealed that HDACis induce specific loss of the nuclear isoform UNG2 independent of transcription and cell-cycle alterations. More than 80% of UNG2 is degraded proteasomally after 24 hours treatment with SAHA, MS275, Valproate or Na-butyrate, indicating a universal ability of HDACis to mediate loss of UNG2. Targeted MS/MS analysis in HEK cells against a panel of proteins involved in DNA repair, translesion synthesis and nucleotide metabolism, revealed that UNG2 was the most pronounced differentially expressed among these after HDACi treatment. 48 hour treatment lead to a 30-40% increase in uracil lesions in the nuclear genome of HeLa and HEK cells and MS275 treatment in murine CH12F3 cell line mediated robust UNG2-loss accompanied by reduced class switch recombination. Furthermore, our analysis identified the PCNA-associated factor PAF15 among the downregulated proteins. PAF15 is overexpressed in many cancers and suppress TLS by inducing double monoubiquitinylation of PCNA and recruitment of the replicative polymerases. In summary, our findings demonstrate that HDAC inhibition affects the levels of proteins involved in DNA base excision repair, translesion synthesis and pyrimidine metabolism. These findings are important for a wide range of clinical applications of HDACi, such as in rheumatology, HIV-, and cancer treatment.
Project description:We performed an mRNA-sequencing experiment using Drosophila midgut to find uracil-induced signaling pathways and biological processes in response to uracil. The sequenced reads from Illumina Hiseq2000 that passed quality filters were mapped to Drosophila genome (NCBI build 5.3) using Tophat and then quantitatively analyzed by HTseq at the gene level. By comparing uracil-treated and non-treated samplesl, we profiled uracil-dependent gene expression changes.
Project description:Antimetabolite chemotherapies increase uracil levels in DNA, and thus identification of factors that influence the uracil content in DNA may have implications for understanding uracil-mediated chromosomal instability. We previously showed in the budding yeast Saccharomyces cerevisiae that uracil content in DNA correlates with replication timing, where the earliest and latest replicating regions are depleted in uracil. Here, we manipulated nucleotide biosynthesis enzymes in budding yeast to determine whether the pattern of uracil incorporation could be altered. In strains with high levels of uracil incorporation, deletion of dCMP deaminase (Dcd1) accelerated uracil incorporation at early-firing origins, likely due to rapid dTTP pool depletion. In contrast, increasing the activity of ribonucleotide reductase, which is required for the synthesis of all dNTPs via ribonucleotide diphosphates, lead to dUTP and dTTP pool equilibration and a concomitant increase in uracil content throughout the genome. These data suggest that uracil availability and the dUTP:dTTP ratio are temporally regulated during S phase and govern uracil incorporation into the genome. Therapeutic manipulation of nucleotide biosynthesis in human cells to either increase the dUTP pool or deplete the dTTP pool in early S phase may therefore improve the efficacy of antimetabolite chemotherapies.
Project description:Uracil DNA glycosylases (UDGs) excise uracil from DNA arising from dUMP misincorporation during replication or from cytosine deamination. Besides functioning in canonical uracil repair, UDGs cooperate with DNA base modifying enzymes to effect mutagenesis or DNA demethylation. Mammalian cells express four UDGs, the functional dissection of which represents a challenge. Here, we used Schizosaccharomyces pombe with only two UDGs, Ung1 and Thp1, as a simpler model to study functional interactions in uracil repair. We show that despite a predominance of Ung1 activity in cell extracts, both UDGs act redundantly against genomic uracil accumulation and mutations from cytosine deamination in cells. Notably, Thp1 but not Ung1-dependent repair is cytotoxic under genomic uracil stress induced by 5-fluorouracil exposure or AID expression. Also, Thp1- but not Ung1-mediated base excision is recombinogenic, accounting for more than 60% of spontaneous mitotic recombination events in a recombination assay. Hence, the qualitative outcome of uracil repair depends on the initiating UDG; while Ung1 shows expected features of a bona-fide DNA repair enzyme, Thp1-initiated repair appears slow and non-productive, implicating a function beyond canonical DNA repair. Given the epigenetic role of mammalian TDGs, we performed transcriptome analyses and identified a possible function of Thp1 in stabilizing gene expression.
Project description:Comparative transcriptome analyses of P. aeruginosa PA14 pyrF mutant with PA14 wild type, and with PA14 pyrF mutant with 1 mM uracil supplement and PA14 wild type with 10 mM uracil in biofilm cells. All samples were cultured in LB with glass wool at 37C for 7h. Keywords: Pseudomonas aeruginosa biofilm pyrF uracil
Project description:Comparative transcriptome analyses of P. aeruginosa PA14 pyrF mutant with PA14 wild type, and with PA14 pyrF mutant with 1 mM uracil supplement and PA14 wild type with 10 mM uracil in biofilm cells. All samples were cultured in LB with glass wool at 37C for 7h. Experiment Overall Design: Strains: P. aeruginosa PA14 wild type, PA14 pyrF mutant Experiment Overall Design: Medium: LB for PA14 wild type and PA14 pyrF mutant, LB with 1 mM uracil for PA14 pyrF mutant, LB with 10 mM uracil for PA14 wild type Experiment Overall Design: Cell type: Biofilm cells grown on glass wool Experiment Overall Design: Time: 7 h Experiment Overall Design: Temperature: 37C
Project description:Comparing transcriptome by means of DNA microarrays of Streptococcus pneumoniae D39 versus D39SM in medium without uracil. Details of this experiment are described in a paper with the title 'Interplay between capsule expression and uracil metabolism in Streptococcus pneumoniae'