Project description:Repair of UV damage from the transcribed strand (TS) of yeast genes is rapid due to the transcription coupled nucleotide excision repair (TC-NER) pathway. TC-NER is triggered when RNA polymerase stalls at UV damage, such as a UV-induced cyclobutane pyrimidine dimer (CPD). During transcription, the histone methyltransferase Set2 methylates histone H3K36, but it is not known if Set2 regulates TC-NER. Here, we report genome-wide repair maps of UV-induced cyclobutane pyrimidine dimers (CPDs) in yeast cells lacking Set2.
Project description:We characterized the role of H3K36 methylation in regulating repair of UV damage from the transcribed strand (TS) of yeast genes by the transcription coupled nucleotide excision repair (TC-NER) pathway. TC-NER is triggered when RNA polymerase stalls at UV damage, such as a UV-induced cyclobutane pyrimidine dimer (CPD). During transcription, the histone methyltransferase Set2 methylates histone H3K36, but it is not known if H3K36 methylation regulates TC-NER. Here, we report genome-wide repair maps of UV-induced cyclobutane pyrimidine dimers (CPDs) in yeast cells containing mutants in histone H3K36 (or set2).
Project description:We developed a method for genome-wide mapping of DNA excision repair named XR-seq (eXcision Repair-seq). Human nucleotide excision repair generates two incisions surrounding the site of damage, creating a ~30-mer. In XR-seq, this fragment is isolated and subjected to high-throughput sequencing. We used XR-seq to produce stranded, nucleotide-resolution maps of repair of two UV-induced DNA damages in human cells, cyclobutane pyrimidine dimers (CPDs) and (6-4) pyrimidine-pyrimidone photoproducts ((6-4)PPs). In wild-type cells, CPD repair was highly associated with transcription, specifically with the template strand. Experiments in cells defective in either transcription-coupled excision repair or general excision repair isolated the contribution of each pathway to the overall repair pattern, and showed that transcription-coupled repair of both photoproducts occurs exclusively on the template strand. XR-seq maps capture transcription-coupled repair at sites of divergent gene promoters and bi-directional eRNA production at enhancers. XR-seq data also uncovered the repair characteristics and novel sequence preferences of CPDs and (6-4)PPs. XR-seq and the resulting repair maps will facilitate studies of the effects of genomic location, chromatin context, transcription, and replication on DNA repair in human cells. We have performed XR-seq for two types of UV-induced damages (CPD and (6-4)PP) in three different cell lines: NHF1, XP-C (XP4PA-SV-EB, GM15983)), and CS-B (CS1ANps3g2, GM16095). Two biological replicates were performed for each experiment, in which independent cell populations were UV treated and subjected to XR-seq.
Project description:We report the application of single-molecule-based sequencing technology (XR-seq) for high-throughput profiling of nucleotide excision repair in Drosophila four developmental stages and S2 cells. By obtaining over six billion bases of sequence from UV and cisplatin damage antibodies immunoprecipitated excision DNA, we generated genome-wide nucleotide excision repair maps of Drosophila Embryo, Larva, Pupa , two gender of adults and S2 cells . We find that Drosophila performs transcription-coupled repair (TCR) at all its developmental stages. S2 cell carry out TCR response to both UV and Cisplatin damage. Finally, we show that XPC repair factor is required for both global and transcription-coupled repair in Drosophila. This study provides the mechanism of nucleotide excision repair of Drosophila in vivo and vitro response to UV and Cisplatin damage.
Project description:We developed a method for genome-wide mapping of DNA excision repair named XR-seq (eXcision Repair-seq). Human nucleotide excision repair generates two incisions surrounding the site of damage, creating a ~30-mer. In XR-seq, this fragment is isolated and subjected to high-throughput sequencing. We used XR-seq to produce stranded, nucleotide-resolution maps of repair of two UV-induced DNA damages in human cells, cyclobutane pyrimidine dimers (CPDs) and (6-4) pyrimidine-pyrimidone photoproducts ((6-4)PPs). In wild-type cells, CPD repair was highly associated with transcription, specifically with the template strand. Experiments in cells defective in either transcription-coupled excision repair or general excision repair isolated the contribution of each pathway to the overall repair pattern, and showed that transcription-coupled repair of both photoproducts occurs exclusively on the template strand. XR-seq maps capture transcription-coupled repair at sites of divergent gene promoters and bi-directional eRNA production at enhancers. XR-seq data also uncovered the repair characteristics and novel sequence preferences of CPDs and (6-4)PPs. XR-seq and the resulting repair maps will facilitate studies of the effects of genomic location, chromatin context, transcription, and replication on DNA repair in human cells.
Project description:Most genotoxic anticancer agents fail in tumors with intact DNA repair. Therefore, trabectedin, a unique agent more toxic to cells with active DNA repair, specifically transcription-coupled nucleotide excision repair (TC-NER), provides new therapeutic opportunities. To unlock the potential of trabectedin and inform its application in precision oncology, a full mechanistic understanding of the drug’s TC-NER-dependent toxicity is needed. Here, we determined that abortive TC-NER of trabectedin-DNA adducts forms persistent single-strand breaks (SSBs) by blocking the second of the two sequential NER incisions by XPG. We mapped the 3’-hydroxyl groups of SSBs originating from the first NER incision at trabectedin lesions, recording TC-NER on a genome-wide scale. We showed that trabectedin-induced SSBs primarily occur in transcribed strands of active genes and peak near transcription start sites. Frequent SSBs were also found outside gene bodies, revealing TC-NER connection to divergent transcription from promoters. This work advances trabectedin as a tool compound for precision oncology and for studying TC-NER and transcription.
Project description:Previous work with the classic T4 Endonuclease V digestion of irradiated Drosophila DNA followed by Southern hybridization led to the conclusion that Drosophila lacked transcription-coupled repair (TCR). This conclusion was reinforced by the Drosophila Genome Project which revealed that Drosophila lacked CSA, CSB, or UVSSA homologs, whose orthologs are present in eukaryotes that carry out TCR ranging from Arabidopsis to humans. A recently developed in vivo excision assay and the Excision Repair-sequencing (XR-seq) method have enabled genome-wide analysis of nucleotide excision repair in various organisms at single nucleotide resolution and strand-specific manner. Using these methods, we have discovered that Drosophila S2 cells carry out robust TCR comparable to that observed in mammalian cells. Our findings provide new insights into the mechanisms of TCR among various species.