Physical and biological parameters affecting DNA double strand break misrejoining in mammalian cells

TY - JOUR

T1 - Physical and biological parameters affecting DNA double strand break misrejoining in mammalian cells

AU - Kühne, M

AU - Rothkamm, K

AU - Löbrich, M

PY - 2002

Y1 - 2002

N2 - In an attempt to investigate the effect of radiation quality, dose and specific repair pathways on correct and erroneous rejoining of DNA double strand breaks (DSBs), an assay was applied that allows the identification and quantification of incorrectly rejoined DSB ends produced by ionising radiation. While substantial misrejoining occurs in mammalian cells after high acute irradiation doses, decreasing misrejoining frequencies were observed in dose fractionation experiments with X rays. In line with this finding, continuous irradiation with gamma rays at low dose rate leads to no detectable misrejoining. This indicates that the probability for a DSB to be misrejoined decreases drastically when DSBs are separated in time and space. The same dose fractionation approach was applied to determine DSB misrejoining after alpha particle exposure. In contrast to the results with X rays, there was no significant decrease in DSB misrejoining with increasing fractionation. This suggests that DSB misrejoining after alpha irradiation is not significantly affected by a separation of particle tracks. To identify the enzymatic pathways that are involved in DSB misrejoining, cell lines deficient in non-homologous end-joining (NHEJ) were examined. After high X ray doses, DSB misrejoining is considerably reduced in NHEJ mutants. Low dose rate experiments show elevated DSB misrejoining in NHEJ mutants compared with wild-type cells. The authors propose that NHEJ serves as an efficient pathway for rejoining correct break ends in situations of separated breaks but generates genomic rearrangements if DSBs are close in time and space.

AB - In an attempt to investigate the effect of radiation quality, dose and specific repair pathways on correct and erroneous rejoining of DNA double strand breaks (DSBs), an assay was applied that allows the identification and quantification of incorrectly rejoined DSB ends produced by ionising radiation. While substantial misrejoining occurs in mammalian cells after high acute irradiation doses, decreasing misrejoining frequencies were observed in dose fractionation experiments with X rays. In line with this finding, continuous irradiation with gamma rays at low dose rate leads to no detectable misrejoining. This indicates that the probability for a DSB to be misrejoined decreases drastically when DSBs are separated in time and space. The same dose fractionation approach was applied to determine DSB misrejoining after alpha particle exposure. In contrast to the results with X rays, there was no significant decrease in DSB misrejoining with increasing fractionation. This suggests that DSB misrejoining after alpha irradiation is not significantly affected by a separation of particle tracks. To identify the enzymatic pathways that are involved in DSB misrejoining, cell lines deficient in non-homologous end-joining (NHEJ) were examined. After high X ray doses, DSB misrejoining is considerably reduced in NHEJ mutants. Low dose rate experiments show elevated DSB misrejoining in NHEJ mutants compared with wild-type cells. The authors propose that NHEJ serves as an efficient pathway for rejoining correct break ends in situations of separated breaks but generates genomic rearrangements if DSBs are close in time and space.

KW - Alpha Particles

KW - Animals

KW - Cell Line

KW - DNA Damage/radiation effects

KW - DNA Repair/radiation effects

KW - Dose-Response Relationship, Radiation

KW - Gene Rearrangement/radiation effects

KW - Kinetics

KW - Linear Energy Transfer

KW - Mammals

KW - X-Rays

U2 - 10.1093/oxfordjournals.rpd.a006742

DO - 10.1093/oxfordjournals.rpd.a006742

M3 - SCORING: Journal article

C2 - 12194264

VL - 99

SP - 129

EP - 132

JO - RADIAT PROT DOSIM

JF - RADIAT PROT DOSIM

SN - 0144-8420

IS - 1-4

ER -