Abstract
We have previously shown that a radiation sensitive medaka mutant ric1 strain has the defects in repair of DSBs, induction of apoptosis and regulation of cell cycle after γ-rays irradiation [Aizawa et al., 2004; Hidaka et al., The 49th Annual Meeting of JRRS], suggesting that the responsible gene, ric1, is involved with the initial steps of DSB repair. It is well known that DSBs are repaired either by homologous recombination (HR) or by non-homologous end-joining (NHEJ) mechanisms. Then we elucidated each repair ability of ric1 cell lines by using HR assay and EJ assay, which can detect HR or NHEJ repair frequency by using reporter constructs and a rare-cutting I-SceI endnuclease. DR-GFP construct for HR assay and End-Joining construct for EJ assay, each containing one or two I-SceI site, express green fluorescent protein when the each construct repair by HR or NHEJ after DNA digestion by I-SceI. We found that the HR repair frequency was significantly lower in ric1 cells than in wild-type cells. We are currently analyzing NHEJ repair frequency, effect of ATM inhibitor and the change in quantity of gamma-H2AX after gamma-rays irradiation. These results will reveal ric1 function. The data will also be presented in the meeting.
