Impaired Repair of Ionizing Radiation-Induced DNA Damage in Cockayne Syndrome Cells

Cockayne syndrome (CS) cells are defective in transcription-coupled repair (TCR) and sensitive to oxidizing agents, including ionizing radiation. We examined the hypothesis that TCR plays a role in ionizing radiation-induced oxidative DNA damage repair or alternatively that CS plays a role in transc...

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Bibliographic Details
Published in:Radiation research 2011-04, Vol.175 (4), p.432-443
Main Authors: Cramers, Patricia, Verhoeven, Esther E, Filon, A. Ronald, Rockx, Davy A. P, Santos, Susy J, van der Leer, Anneke A, Kleinjans, Jos C. S, van Zeeland, Albert A, Mullenders, Leon H. F
Format: Article
Language:English
Subjects:
Cell lines
Cell Survival - radiation effects
Cells, Cultured
Cockayne Syndrome - genetics
Cockayne Syndrome - pathology
DNA
DNA damage
DNA Damage - genetics
DNA Repair - genetics
DNA Repair - radiation effects
Dose-Response Relationship, Radiation
Fibroblasts
Humans
Irradiation
Lesions
Radiation damage
Radiation Dosage
REGULAR ARTICLES
RNA
Solar X rays
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Summary:Cockayne syndrome (CS) cells are defective in transcription-coupled repair (TCR) and sensitive to oxidizing agents, including ionizing radiation. We examined the hypothesis that TCR plays a role in ionizing radiation-induced oxidative DNA damage repair or alternatively that CS plays a role in transcription elongation after irradiation. Irradiation with doses up to 100 Gy did not inhibit RNA polymerase II-dependent transcription in normal and CS-B fibroblasts. In contrast, RNA polymerase I-dependent transcription was severely inhibited at 5 Gy in normal cells, indicating different mechanisms of transcription response to X rays. The frequency of radiation-induced base damage was 2 × 10−7 lesions/base/Gy, implying that 150 Gy is required to induce one lesion/30-kb transcription unit; no TCR of X-ray-induced base damage in the p53 gene was observed. Therefore, it is highly unlikely that defective TCR underlies the sensitivity of CS to ionizing radiation. Overall genome repair levels of radiation-induced DNA damage measured by repair replication were significantly reduced in CS-A and CS-B cells. Taken together, the results do not provide evidence for a key role of TCR in repair of radiation-induced oxidative damages in human cells; rather, impaired repair of oxidative lesions throughout the genome may contribute to the CS phenotype.
ISSN:0033-7587
1938-5404
DOI:10.1667/RR1972.1