Functional relationships of FANCC to homologous recombination, translesion synthesis, and BLM

• Published in: The EMBO journal 2005-01, Vol.24 (2), p.418-427
• Main Authors: Hirano, Seiki, Yamamoto, Kazuhiko, Ishiai, Masamichi, Yamazoe, Mitsuyoshi, Seki, Masayuki, Matsushita, Nobuko, Ohzeki, Mioko, Yamashita, Yukiko M, Arakawa, Hiroshi, Buerstedde, Jean-Marie, Enomoto, Takemi, Takeda, Shunichi, Thompson, Larry H, Takata, Minoru
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - physiology; Avian Proteins; Bloom syndrome; Blotting, Western; Cell Cycle Proteins - physiology; Cell Line; Chickens; DNA Helicases - physiology; DNA Replication; DNA-Binding Proteins - physiology; EMBO13; Fanconi anemia; Fanconi Anemia Complementation Group C Protein; Fanconi Anemia Complementation Group Proteins; Green Fluorescent Proteins - metabolism; homologous recombination; Humans; Immunoprecipitation; Mutants; Nuclear Proteins - physiology; Poultry; Rad51 Recombinase; Recombinant Fusion Proteins - metabolism; Recombination, Genetic - genetics; RecQ Helicases; Reverse Transcriptase Polymerase Chain Reaction; Sister Chromatid Exchange; translesion synthesis; Ubiquitin-Protein Ligases
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/sj.emboj.7600534

Some of the restarting events of stalled replication forks lead to sister chromatid exchange (SCE) as a result of homologous recombination (HR) repair with crossing over. The rate of SCE is elevated by the loss of BLM helicase or by a defect in translesion synthesis (TLS). We found that spontaneous SCE levels were elevated ∼2‐fold in chicken DT40 cells deficient in Fanconi anemia (FA) gene FANCC . To investigate the mechanism of the elevated SCE, we deleted FANCC in cells lacking Rad51 paralog XRCC3 , TLS factor RAD18 , or BLM . The increased SCE in fancc cells required Xrcc3, whereas the fancc/rad18 double mutant exhibited higher SCE than either single mutant. Unexpectedly, SCE in the fancc/blm mutant was similar to that in blm cells, indicating functional linkage between FANCC and BLM. Furthermore, MMC‐induced formation of GFP‐BLM nuclear foci was severely compromised in both human and chicken fancc or fancd2 cells. Our cell survival data suggest that the FA proteins serve to facilitate HR, but not global TLS, during crosslink repair.