Rs. Tebbs et al., CORRECTION OF CHROMOSOMAL INSTABILITY AND SENSITIVITY TO DIVERSE MUTAGENS BY A CLONED CDNA OF THE XRCC3 DNA-REPAIR GENE, Proceedings of the National Academy of Sciences of the United Statesof America, 92(14), 1995, pp. 6354-6358
The mutagen-sensitive CHO line irs1SF was previously isolated on the b
asis of hypersensitivity to ionizing radiation and was found to be chr
omosomally unstable as well as cross-sensitive to diverse kinds of DNA
-damaging agents. The analysis of somatic cell hybrids formed between
irs1SF and human lymphocytes implicated a human gene (defined as XRCC3
; x-ray repair cross-complementing), which partially restored mitomyci
n C resistance to the mutant. A functional cDNA that confers mitomycin
C resistance was transferred to irs1SF cells by transforming them wit
h an expression cDNA library and obtaining primary and secondary trans
formants. Functional cDNA clones were recovered from a cosmid library
prepared from a secondary transformant. Transformants also showed part
ial correction of sensitivity to cisplatin and gamma-rays, efficient c
orrection of chromosomal instability, and substantially improved plati
ng efficiency and growth rate. The XRCC3 cDNA insert is approximate to
2.5 kb and detects an approximate to 3.0-kb mRNA on Northern blots, T
he cDNA was mapped by fluorescence in situ hybridization to human chro
mosome 14q32.3, which was consistent with the chromosome concordance d
ata of two independent hybrid clone panels.