Homologous recombination, but not DNA repair, is reduced in vertebrate cells deficient in RAD52.
Rad52 plays a pivotal role in double-strand break (DSB) repair and genetic recombination in Saccharomyces cerevisiae, where mutation of this gene leads to extreme X-ray sensitivity and defective recombination. Yeast Rad51 and Rad52 interact, as do their human homologues, which stimulates Rad51-mediated DNA strand exchange in vitro, suggesting that Rad51 and Rad52 act cooperatively. To define the role of Rad52 in vertebrates, we generated RAD52(-/-) mutants of the chicken B-cell line DT40. Surprisingly, RAD52(-/-) cells were not hypersensitive to DNA damages induced by gamma-irradiation, methyl methanesulfonate, or cis-platinum(II)diammine dichloride (cisplatin). Intrachromosomal recombination, measured by immunoglobulin gene conversion, and radiation-induced Rad51 nuclear focus formation, which is a putative intermediate step during recombinational repair, occurred as frequently in RAD52(-/-) cells as in wild-type cells. Targeted integration frequencies, however, were consistently reduced in RAD52(-/-) cells, showing a clear role for Rad52 in genetic recombination. These findings reveal striking differences between S. cerevisiae and vertebrates in the functions of RAD51 and RAD52.
Bayer-chair Department of Molecular Immunology and Allergology, Faculty of Medicine, Kyoto University, Konoe Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
Y
Y
Yamaguchi-Iwai
E
E
Sonoda
J M
JM
Buerstedde
O
O
Bezzubova
C
C
Morrison
M
M
Takata
A
A
Shinohara
S
S
Takeda
D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002645:Chickens; D002945:Cisplatin / Q000494:pharmacology; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D018390:Gene Targeting; D007075:Immunoglobulin M / Q000276:immunology; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D009153:Mutagens / Q000494:pharmacology; D011995:Recombination, Genetic / Q000235:genetics*; D014162:Transfection / Q000592:standards; D014965:X-Rays
D004268:DNA-Binding Proteins; D007075:Immunoglobulin M; D009153:Mutagens; D008741:Methyl Methanesulfonate; D002945:Cisplatin