Host: The Japan Radiation Research Society
Co-host: Asian Association for Radiation Research
Werner syndrome (WS) is an autosomal recessive disorder with premature aging. The gene defective in WS, WRN, is located on chromosome 8p. Because the WS gene product (WRN) interacts with several proteins involed in DNA repair in vitro, it has been hypothesized that WRN is involved in DNA repair. However, we found that cells derived from WS patient are not particularly sensitive to ionizing radiation (IR) compared with the control cells in vivo. This result suggests that WRN is not directly involved in DNA double-strand break repair, or that cell cycle-dependent radiation sensitivity of WS cells could be masked in the former assay. In the present study, we investigated whether the cell cycle-specific DNA repair in WS cells is defective or not. Two cell lines used are BJ1-hTERT (hTERT-immortalized normal human fibloblasts) and WS3RGB-T (hTERT-immortalized WS fibroblasts). For the detection of DNA damage, we examined phosphorylated-ATM foci in 1 Gy-irradiated cells. Each cell cycle phases are visualized by cell cycle specific marker, and cells in S and G2 phases were stained with anti-RPA antibody and anti-phosphorylated-hitone H3 antibody, respectively. Without irradiation, the numbers of the foci per cell is slightly higher in WS cells than in the control cells. Immediately after irradiation, both cell lines showed the similar numbers of foci in S and G2 phases, and the foci disappeared similarly thereafter. These results confirm that WRN is not directly involved in DNA double strand repair in both S and G2 phases.
