Histone modifications are major determinants of DNA double-strand break (DSB) response and repair. Here we elucidate a DSB repair function for transcription-coupled Set2 methylation at H3 lysine 36 (H3K36me). Cells devoid of Set2/H3K36me are hypersensitive to DNA-damaging agents and site-specific DSBs, fail to properly activate the DNA-damage checkpoint, and show genetic interactions with DSB-s...

In the budding yeast, Saccharomyces cerevisiae, genes in close proximity to telomeres are subject to transcriptional silencing through the process of telomere position effect (TPE). Here, we show that the protein Ku, previously implicated in DNA double-strand break (DSB) repair and in telomeric length maintenance, is also essential for telomeric silencing. Furthermore, using an in vivo plasmid ...

Akt phosphorylation has previously been described to be involved in mediating DNA damage repair through the nonhomologous end-joining (NHEJ) repair pathway. Yet the mechanism how Akt stimulates DNA-protein kinase catalytic subunit (DNA-PKcs)-dependent DNA double-strand break (DNA-DSB) repair has not been described so far. In the present study, we investigated the mechanism by which Akt can inte...

The prevailing hypothesis on the mechanism of radiation-induced cell killing identifies the genetic material deoxyribonucleic acid (DNA) as the most important subcellular target at biologically relevant doses. In this review we present new data and summarize the role of the DNA double-strand breaks (dsb) induced by ionizing radiation and DNA dsb rejoining as determinants of cellular radiosensit...

Accurate repair of DNA double-strand breaks (DSB) caused during DNA replication and by exogenous stresses is critical for the maintenance of genomic integrity. There is growing evidence that the Polo-like kinase 1 (Plk1) that plays a number of pivotal roles in cell proliferation can directly participate in regulation of DSB repair. In this study, we show that Plk1 regulates BRCA1, a key mediato...

We studied the relation between initial DNA double-strand breaks (DNA-DSB) and the rejoining kinetics of the strand breaks, as well as the OER (oxygen enhancement ratio) after low- and high-LET (linear energy transfer) radiations. CHO cells were exposed to 200 kVp X-rays or 80 keV/microm carbon ions under oxic and hypoxic conditions. DNA-DSB in the cells were analyzed by a static-field gel elec...

Camptothecin (CPT) and its analogues are chemotherapeutic agents that covalently and reversibly link DNA Topoisomerase I to its nicked DNA intermediate eliciting the formation of DNA double strand breaks (DSB) during replication. The repair of these DSB involves multiple DNA damage response and repair proteins. Here we demonstrate that CPT-induced DNA damage promotes functional interactions bet...

Pulsed field gel electrophoresis (PFGE) is widely used to measure DNA double strand breaks (dsb). The DNA of cultured cells can be prelabelled with radioactivity, which helps greatly in detection and quantitation of DNA dsb. However, this approach cannot be used with non-cycling cells from biopsy material. We describe a method which uses SYBR Green I to stain DNA in dried agarose gels. DNA is d...

Rat embryo cells (REC) transformed by the H-ras oncogene plus the cooperating oncogene »-m.tr are highly resistant to ionizing radiation as compared with the nontransformed parent cells, REC, or immortalized REC. In an attempt to understand the potential mechanism of resistance in these cells, the induction and repair of double strand breaks (dsb) in DNA were measured in a ll-ras plus \-myc tr...

Rat embryo cells (REC) transformed by the H-ras oncogene plus the cooperating oncogene v-myc are highly resistant to ionizing radiation as compared with the nontransformed parent cells, REC, or immortalized REC. In an attempt to understand the potential mechanism of resistance in these cells, the induction and repair of double strand breaks (dsb) in DNA were measured in a H-ras plus v-myc trans...