The functional roles of ric1 in DNA damage response

Abstract

A medaka cultured cell line RIC1-e9 has defects in the pathways of apoptosis and cell cycle regulation (49th JRR). Comet assay revealed that RIC1-e9 cells required about 2h to repair the DSBs induced by IR, while in CAB cells the process was completed within 30min (13th ICRR). In this study, we established other cell lines (RIC1) to confirm that the defects are common characteristics of RIC1 cell lines. In 24h after γ-irradiation, 30% of the CAB cells were apoptotic. In contrast, apoptotic and fragmented RIC1-e42 cells and RIC1-e44 cells were very few. CAB cells and RIC1 cells showed mitotic inhibition immediately after irradiation, but same as RIC1-e9, both of RIC1-e42 and RIC1-e44 resumed cell division earlier than the CAB cells. In addition, in RIC1-e9 cells fewer H2AX were phosphorylated than in CAB-e3 cells after γ-irradiation. Comet assay and immunohistochemistry analysis with RIC1-e42 and RIC1-e44 ensure the relation between the intensity of fluorescence to phosphorylated H2AX and the time for repair.