High Frequency and Error-prone DNA Recombination in Ataxia Telangiectasia Cell Lines (∗)

The only specific DNA repair defect found in ataxia telangiectasia (A-T) cells is mis-repair of cleaved DNA. In this report we measured DNA recombination, given its role in DNA repair and genetic instability. Using plasmids containing selectable reporter genes, we found a higher frequency of both ch...

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Bibliographic Details
Published in:The Journal of biological chemistry 1996-02, Vol.271 (8), p.4497-4503
Main Authors: Luo, Chen-Mei, Tang, Wei, Mekeel, Kristin L., DeFrank, Jeffrey S., Anné, P. Rani, Powell, Simon N.
Format: Article
Language:English
Subjects:
Ataxia Telangiectasia - genetics
Ataxia Telangiectasia - metabolism
Cell Line
Cell Line, Transformed
Cinnamates
DNA - biosynthesis
DNA - genetics
DNA Repair - genetics
Humans
Hygromycin B - analogs & derivatives
Hygromycin B - pharmacology
Pentosyltransferases - biosynthesis
Pentosyltransferases - genetics
Plasmids
Recombinant Proteins - biosynthesis
Recombination, Genetic
Restriction Mapping
Sequence Deletion
Simian virus 40 - genetics
Transfection
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Summary:The only specific DNA repair defect found in ataxia telangiectasia (A-T) cells is mis-repair of cleaved DNA. In this report we measured DNA recombination, given its role in DNA repair and genetic instability. Using plasmids containing selectable reporter genes, we found a higher frequency of both chromosomal recombination (>100 times) and extra-chromosomal recombination (27 times) in SV40-transformed A-T cell lines compared with in an SV40-transformed normal fibroblast cell line. Southern analysis of single A-T colonies exhibiting post-integration recombination revealed that 24/27 had undergone aberrant rearrangements; recombination in normal fibroblast colonies was achieved by gene conversion in 8/11 clones and 10/11 clones showed unchanged copies of the plasmid. Using co-transfection of two integrating plasmids, each containing a separate deletion in the xgprt reporter gene, the 27 times difference in extra-chromosomal recombination was found when the plasmids were cleaved at a distance from the reporter gene. When the plasmids were cleaved within the reporter gene, the co-transfection frequency was reduced in A-T, but was increased in normal cells. We conclude that A-T cell lines have not only a high frequency chromosomal and extra-chromosomal recombination, but also exhibit error-prone recombination of cleaved DNA.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.271.8.4497