Radiation-induced genomic rearrangements formed by nonhomologous end-joining of DNA double-strand breaks
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Radiation-induced genomic rearrangements formed by nonhomologous end-joining of DNA double-strand breaks. / Rothkamm, K; Kühne, M; Jeggo, P A; Löbrich, M.
in: CANCER RES, Jahrgang 61, Nr. 10, 15.05.2001, S. 3886-93.Publikationen: SCORING: Beitrag in Fachzeitschrift/Zeitung › SCORING: Zeitschriftenaufsatz › Forschung › Begutachtung
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TY - JOUR
T1 - Radiation-induced genomic rearrangements formed by nonhomologous end-joining of DNA double-strand breaks
AU - Rothkamm, K
AU - Kühne, M
AU - Jeggo, P A
AU - Löbrich, M
PY - 2001/5/15
Y1 - 2001/5/15
N2 - Two major pathways for repairing DNA double-strand breaks (DSBs) have been identified in mammalian cells, nonhomologous end-joining (NHEJ) and homologous recombination (HR). Inactivation of NHEJ is known to lead to an elevated level of spontaneous and radiation-induced chromosomal rearrangements associated with an increased risk of tumorigenesis. This has raised the idea of a caretaker role for NHEJ. It is, however, not known whether NHEJ itself can also cause rearrangements. To investigate, on the DNA level, the influence of a defect in NHEJ on the formation of genomic rearrangements, we applied an assay based on Southern hybridization that allows the identification and quantification of incorrectly rejoined DSB ends produced by ionizing radiation. After 80 Gy of X-irradiation at a high dose rate (23 Gy/min), wild-type cells repaired 50% of the induced DSBs within 24 h by incorrect rejoining. This frequency of DSB misrejoining is considerably reduced in NHEJ-deficient cells. Low-dose-rate experiments, in which the cells were exposed to 80 Gy over a period of 14 days under repair conditions, led to no detectable misrejoining in wild-type cells but revealed a misrejoining frequency of 10% in NHEJ-deficient cells. This shows that in situations of separated breaks, NHEJ deficiency leads to genomic rearrangements, in agreement with chromosomal studies. However, if multiple DSBs coincide, even wild-type cells form genomic rearrangements frequently. These repair events are absent in Ku80-, DNA-PKcs-, and DNA ligase IV-deficient cells but are present in RAD54(-/-) cells. This strongly suggests that NHEJ has, in addition to its caretaker role, also the potential to effect genomic rearrangements. We propose that it 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 - Two major pathways for repairing DNA double-strand breaks (DSBs) have been identified in mammalian cells, nonhomologous end-joining (NHEJ) and homologous recombination (HR). Inactivation of NHEJ is known to lead to an elevated level of spontaneous and radiation-induced chromosomal rearrangements associated with an increased risk of tumorigenesis. This has raised the idea of a caretaker role for NHEJ. It is, however, not known whether NHEJ itself can also cause rearrangements. To investigate, on the DNA level, the influence of a defect in NHEJ on the formation of genomic rearrangements, we applied an assay based on Southern hybridization that allows the identification and quantification of incorrectly rejoined DSB ends produced by ionizing radiation. After 80 Gy of X-irradiation at a high dose rate (23 Gy/min), wild-type cells repaired 50% of the induced DSBs within 24 h by incorrect rejoining. This frequency of DSB misrejoining is considerably reduced in NHEJ-deficient cells. Low-dose-rate experiments, in which the cells were exposed to 80 Gy over a period of 14 days under repair conditions, led to no detectable misrejoining in wild-type cells but revealed a misrejoining frequency of 10% in NHEJ-deficient cells. This shows that in situations of separated breaks, NHEJ deficiency leads to genomic rearrangements, in agreement with chromosomal studies. However, if multiple DSBs coincide, even wild-type cells form genomic rearrangements frequently. These repair events are absent in Ku80-, DNA-PKcs-, and DNA ligase IV-deficient cells but are present in RAD54(-/-) cells. This strongly suggests that NHEJ has, in addition to its caretaker role, also the potential to effect genomic rearrangements. We propose that it 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 - Animals
KW - CHO Cells
KW - Cell Line
KW - Cricetinae
KW - DNA/genetics
KW - DNA Damage
KW - DNA Helicases
KW - DNA Ligase ATP
KW - DNA Ligases/metabolism
KW - DNA Repair/genetics
KW - DNA Repair Enzymes
KW - DNA-Activated Protein Kinase
KW - DNA-Binding Proteins
KW - Fibroblasts
KW - Fungal Proteins/genetics
KW - G1 Phase/physiology
KW - Gene Rearrangement/radiation effects
KW - Humans
KW - Mice
KW - Nuclear Proteins
KW - Protein-Serine-Threonine Kinases/metabolism
KW - Saccharomyces cerevisiae Proteins
M3 - SCORING: Journal article
C2 - 11358801
VL - 61
SP - 3886
EP - 3893
JO - CANCER RES
JF - CANCER RES
SN - 0008-5472
IS - 10
ER -