Gene conversion tracts from double-strand break repair in mammalian cells Journal Article


Authors: Elliott, B.; Richardson, C.; Winderbaum, J.; Nickoloff, J. A.; Jasin, M.
Article Title: Gene conversion tracts from double-strand break repair in mammalian cells
Abstract: Mammalian cells are able to repair chromosomal double-strand breaks (DSBs) both by homologous recombination and by mechanisms that require little or no homology. Although spontaneous homologous recombination is rare, DSBs will stimulate recombination by 2 to 3 orders of magnitude when homology is provided either from exogenous DNA in gene-targeting experiments or from a repeated chromosomal sequence. Using a gene-targeting assay in mouse embryonic stem cells, we now investigate the effect of heterology on recombinational repair of DSBs. Cells were cotransfected with an endonuclease expression plasmid to induce chromosomal DSBs and with substrates containing up to 1.2% heterology from which to repair the DSBs. We find that heterology decreases the efficiency of recombinational repair, with 1.2% sequence divergence resulting in an approximately sixfold reduction in recombination. Gene conversion tract lengths were examined in 80 recombinants. Relatively short gene conversion tracts were observed, with 80% of the recombinants having tracts of 58 bp or less. These results suggest that chromosome ends in mammalian cells are generally protected from extensive degradation prior to recombination. Gene conversion tracts that were long (up to 511 bp) were continuous, i.e., they contained an uninterrupted incorporation of the silent mutations. This continuity suggests that these long tracts arose from extensive degradation of the ends or from formation of heteroduplex DNA which is corrected with a strong bias in the direction of the unbroken strand.
Keywords: nonhuman; animal cell; dna recombination; mouse; mammalia; animals; mice; dna damage; gene targeting; dna repair; embryo; cell line; animalia; stem cell; dna strand breakage; gene conversion; priority journal; article
Journal Title: Molecular and Cellular Biology
Volume: 18
Issue: 1
ISSN: 0270-7306
Publisher: American Society for Microbiology  
Date Published: 1998-01-01
Start Page: 93
End Page: 101
Language: English
PUBMED: 9418857
PROVIDER: scopus
PMCID: PMC121458
DOI: 10.1128/MCB.18.1.93
DOI/URL:
Notes: Article -- Export Date: 12 December 2016 -- Source: Scopus
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  1. Maria Jasin
    251 Jasin