Strand invasion involving short tract gene conversion is specifically suppressed in BRCA2-deficient hamster cells.
The BRCA2 tumour suppressor protein is involved in maintaining genetic stability through its role in homologous recombination (HR), where it mediates RAD51-dependent strand invasion. Here, we show that BRCA2-defective cells are not completely impaired in HR by strand invasion although the spontaneous HR rate is 10-fold lower than that in wild-type cells. Furthermore, a DNA double-strand break (DSB) triggers HR repair by strand invasion also in BRCA2-defective cells, but less efficiently. Thus, either the strand invasion pathway(s) in which BRCA2 operates is still operative in the absence of a functional BRCA2, albeit at a reduced frequency, or there is a separate pathway for strand invasion still functional in BRCA2-deficient cells. Consistent with the latter hypothesis, we show that HR events occurring in BRCA2-defective cells differ from HR events in wild-type cells. These data suggest that BRCA2-defective hamster cells are impaired in short tract gene conversion but maintain proficiency in sister chromatid exchange.
Saleh-Gohari
Nasrollah
N
The Institute for Cancer Studies, University of Sheffield, Medical School, Beech Hill Road, Sheffield S10 2RX, UK.
Helleday
Thomas
T
D000818:Animals; D024682:BRCA2 Protein / Q000235:genetics*; D006224:Cricetinae; D004249:DNA Damage; D004260:DNA Repair; D005785:Gene Conversion; D011995:Recombination, Genetic; D012854:Sister Chromatid Exchange
D024682:BRCA2 Protein