Competition effects ; Dna damage responses ; Nuclear ; Nuclear sites ; Radiation treatments ; Roaming; Single cells ; Single ions ; Strand breaks ; Strong bindings ; Time courses, Competition ; DNA; Genes ; Nucleic acids ; Organic acids, Binding sites, ATM protein ; cell nucleus DNA ; histone H2AX ; Rad51 protein, article ; binding site ; competition ; DNA damage ; DNA repair ; double stranded DNA break ; epifluorescence microscopy ; female ; human ; human cell ; image processing ; immunofluorescence ; irradiation ; kinetics ; radiation exposure ; radiation response ; topography, DNA ; DNA Damage ; DNA Repair ; Dose-Response Relationship, Radiation; Humans ; Microscopy, Fluorescence ; Radiation Dosage «
Competition effects ; Dna damage responses ; Nuclear ; Nuclear sites ; Radiation treatments ; Roaming; Single cells ; Single ions ; Strand breaks ; Strong bindings ; Time courses, Competition ; DNA; Genes ; Nucleic acids ; Organic acids, Binding sites, ATM protein ; cell nucleus DNA ; histone H2AX ; Rad51 protein, article ; binding site ; competition ; DNA damage ; DNA repair ; double stranded DNA break ; epifluorescence microscopy ; female ; human ; human cell ; image... »
Abstract:
We have built an ion-microbeam for studies of the nuclear topography and kinetics of double-strand break repair at the single cell level. Here, we show that a first and a second, delayed single ion exposure at different nuclear sites led to comparable accumulations of phospho-ATM, γ-H2AX and Mdc1 at both earlier (e) and later (l) microirradiated sites. In contrast, accumulations of 53BP1 and the recombination protein Rad51 were strongly reduced at l-sites. This apparent competition effect is accompanied by a reduced amount of 53BP1 in undamaged areas of the irradiated nuclei. We suggest that a critically limited pool size combined with strong binding at irradiated sites leads to the exhaustion of unbound factors freely roaming the nuclear space. The undersupply of these factors at l-sites requires in addition a long-lasting binding at e-sites or a weaker binding at l-sites. The observed effects suggest that DNA damage response at individual nuclear sites depends on the time course of damage load. This may have implications for therapeutic radiation treatments. «
We have built an ion-microbeam for studies of the nuclear topography and kinetics of double-strand break repair at the single cell level. Here, we show that a first and a second, delayed single ion exposure at different nuclear sites led to comparable accumulations of phospho-ATM, γ-H2AX and Mdc1 at both earlier (e) and later (l) microirradiated sites. In contrast, accumulations of 53BP1 and the recombination protein Rad51 were strongly reduced at l-sites. This apparent competition effect is acc... »