A Fourth Complementation Group among Ionizing Radiation-Sensitive Chinese Hamster Cell Mutants Defective in DNA Double-Strand Break Repair

• Published in: Radiation research Vol. 131; no. 3; pp. 309 - 314
• Main Authors: Zdzienicka, M. Z., van Wessel, N., van der Schans, G. P.
• Format: Journal Article
• Language: English
• Published: Oak Brook, Il Academic Press, Inc 01-09-1992; Radiation Research Society
• Subjects: Animals; Biological and medical sciences; Biotechnology; Cell lines; Cells, Cultured; Complementation; Cricetinae; Cultured cells; DNA; DNA damage; DNA Repair; Fundamental and applied biological sciences. Psychology; Genetic Complementation Test; Genetic technics; Ionizing radiation; Irradiation; Methods. Procedures. Technologies; Mutation; Radiation damage; Radiation dosage; Radiation Tolerance; Solar X rays; Cell culture; Animal; DNA; Radiation injury; Defect; X ray; Experimental study; Repair
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3578421

The XR-V9B mutant of Chinese hamster V79 cells which exhibits hypersensitivity to ionizing radiation was isolated by the replica plating technique. The increased sensitivity of XR-V9B cells to X rays (approximately 4-fold, as judged by the $D_{10}$) was accompanied by increased sensitivity to other DNA-damaging agents such as bleomycin (∼17-fold), VP16 (∼6-fold), and adriamycin (∼5-fold). Only a slightly increased sensitivity was observed after exposure to UV radiation, MMS, or mitomycin C (1.4-, 1.7-, and 2-fold, respectively). As measured by neutral elution after exposure to X rays, XR-V9B cells showed a defect in the rejoining of double-strand breaks (DSBs); after 4 h of repair more than 50% of DSBs remained in comparison to 5% in wild-type cells. No difference was observed in the kinetics of single-strand break rejoining between XR-V9B and wild-type cells, as measured by alkaline elution. To determine whether XR-V9B represents a new complementation group among ionizing radiation-sensitive Chinese hamster cell mutants defective in DSB repair, XR-V9B cells were fused with XR-V15B, XR-1, and V-3 cells, which have impaired DSB rejoining and belong to three different complementation groups. In all cases, the derived hybrids regained the sensitivity of wild-type cells when exposed to X rays, indicating that the XR-V9B mutant represents a new fourth complementation group among X-ray-sensitive Chinese hamster cell mutants defective in DSB repair.