title: An approach to estimate radioadaptation from DSB repair efficiency.
abstract: In this review, we would like to introduce a unique approach for the estimation of radioadaptation. Recently, we proposed a new methodology for evaluating the repair efficiency of DNA double-strand breaks (DSB) using a model system. The model system can trace the fate of a single DSB, which is introduced within intron 4 of the TK gene on chromosome 17 in human lymphoblastoid TK6 cells by the expression of restriction enzyme I-SceI. This methodology was first applied to examine whether repair of the DSB (at the I-SceI site) can be influenced by low-dose, low-dose rate gamma-ray irradiation. We found that such low-dose IR exposure could enhance the activity of DSB repair through homologous recombination (HR). HR activity was also enhanced due to the pre-IR irradiation under the established conditions for radioadaptation (50 mGy X-ray-6 h-I-SceI treatment). Therefore, radioadaptation might account for the reduced frequency of homozygous loss of heterozygosity (LOH) events observed in our previous experiment (50 mGy X-ray-6 h-2 Gy X-ray). We suggest that the present evaluation of DSB repair using this I-SceI system, may contribute to our overall understanding of radioadaptation.
authors.affiliation: Metallomics Imaging Research Unit, Center for Molecular Imaging Science, The Institute of Physical and Chemical Research (RIKEN), Saitama, Japan. yatagai@riken.jp
authors.forename: Fumio
authors.initials: F
authors.lastname: Yatagai
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sugasawa
authors.forename: Shuichi
authors.initials: S
authors.lastname: Enomoto
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Honma
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics* / Q000528:radiation effects*; D004249:DNA Damage / Q000502:physiology*; D004260:DNA Repair / Q000502:physiology* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D008957:Models, Genetic; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000502:physiology* / Q000528:radiation effects