Project description:Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3B, A3B) is a key molecular driver inducing mutations in multiple human cancer. A3B belongs to the APOBEC3 enzyme family, which consists seven closely related DNA deaminases that catalyse cytosine-to-uracil (C>U) editing of single-stranded DNA (ssDNA). Here, we used DSBCapture-seq to study the formation of DNA double-strand breaks (DSB) by estrogen receptor activation upon 17-estradiol (E2) induction. The effect of A3B-depletion on DSB formation was investigated using RNA interference.
Project description:Doxorubicin is a widely used chemotherapeutic drug that intercalates between DNA base-pairs and posions Topoisomerase II, although the mechanistic basis for cell killing remains speculative. Here we show that both anthracyclines and Topoisomerase II poison cause enhanced DNA double-strand breaks around CpG island promoters of active genes genome-wide. We propose that torsion-based enhancement of nucleosome turnover exposes promoter DNA, ultimately causing DNA breaks around promoters that contributes to cell killing. We have analyzed mouse squamous cell carcinoma cells treated with doxorubicin, aclarubicin and etoposide. The direct in situ Breaks Labeling, Enrichment on Streptavidin (BLESS, PMID 23503052) method was used for mapping DNA double-strand breaks genome-wide.
Project description:Mapping physiological double strand breaks (DSBs) in cancer cells uncovers transcription-coupled repair mechanism at oncogenic super-enhancers in which RAD51 of the homologous recombination pathway plays a key role supporting the hyper-transcription of related oncogenes.
Project description:In depth analysis of double strand break signaling was performed using mouse Pre-B cells and Human HCT116 cells. Our analysis included the induction of double strand breaks with ionizing radiation with the addition of ATM and DNA-PKcs inhibitors, alone and in combination.
Project description:High concentration of NaCl increases DNA breaks both in cell culture and in vivo. The breaks remain elevated as long as NaCl concentration remains high and are rapidly repaired when the concentration is lowered. Repair of the breaks after NaCl is reduced is accompanied by formation of foci containing phosphorylated H2AX (γH2AX), which occurs around DNA double-strand breaks and contributes to their repair. By chromatin immunoprecipitation using anti-γH2AX antibody, followed by massive parallel sequencing (ChIP-Seq), we find that during repair of double–strand breaks induced by high NaCl, γH2AX is predominantly localized to regions of the genome devoid of genes (“gene deserts”), indicating that the high NaCl-induced double-strand breaks are located there. Localization to gene deserts helps explain why the DNA breaks are less harmful than are the random breaks induced by genotoxic agents such as UV radiation, ionizing radiation and oxidants. We propose that the universal presence of NaCl around animal cells has directly influenced the evolution of the structure of their genomes.
Project description:In relation with the study of the meiotic dynamic of H3K4 methylation, we determined the meiotic Double Strand Breaks (DSB) profiles of wild-type and set1∆ cells.