title: Fanconi anemia complementation group D2 (FANCD2) functions independently of BRCA2- and RAD51-associated homologous recombination in response to DNA damage.
abstract: The BRCA2 breast cancer tumor suppressor is involved in the repair of double strand breaks and broken replication forks by homologous recombination through its interaction with DNA repair protein Rad51. Cells defective in BRCA2.FANCD1 are extremely sensitive to mitomycin C (MMC) similarly to cells deficient in any of the Fanconi anemia (FA) complementation group proteins (FANC). These observations suggest that the FA pathway and the BRCA2 and Rad51 repair pathway may be linked, although a functional connection between these pathways in DNA damage signaling remains to be determined. Here, we systematically investigated the interaction between these pathways. We show that in response to DNA damage, BRCA2-dependent Rad51 nuclear focus formation was normal in the absence of FANCD2 and that FANCD2 nuclear focus formation and mono-ubiquitination appeared normal in BRCA2-deficient cells. We report that the absence of BRCA2 substantially reduced homologous recombination repair of DNA breaks, whereas the absence of FANCD2 had little effect. Furthermore, we established that depletion of BRCA2 or Rad51 had a greater effect on cell survival in response to MMC than depletion of FANCD2 and that depletion of BRCA2 in FANCD2 mutant cells further sensitized these cells to MMC. Our results suggest that FANCD2 mediates double strand DNA break repair independently of Rad51-associated homologous recombination.
authors.affiliation: Department of Laboratory Medicine and Pathology, College of Medicine, Rochester, Minnesota 55905, USA.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ohashi
authors.forename: Malgorzata Z
authors.initials: MZ
authors.lastname: Zdzienicka
authors.forename: Junjie
authors.initials: J
authors.lastname: Chen
authors.forename: Fergus J
authors.initials: FJ
authors.lastname: Couch
mesh_terms: D024682:BRCA2 Protein / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002469:Cell Separation; D002470:Cell Survival; D004396:Coloring Agents / Q000494:pharmacology; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D052236:Fanconi Anemia Complementation Group D2 Protein; D005434:Flow Cytometry; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D016685:Mitomycin / Q000494:pharmacology; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000502:physiology*; D034622:RNA Interference; D051135:Rad51 Recombinase; D011839:Radiation, Ionizing; D011995:Recombination, Genetic; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D024682:BRCA2 Protein; D004396:Coloring Agents; D004268:DNA-Binding Proteins; C499905:FANCD2 protein, human; D052236:Fanconi Anemia Complementation Group D2 Protein; D009687:Nuclear Proteins; D013778:Tetrazolium Salts; D013844:Thiazoles; D049452:Green Fluorescent Proteins; D016685:Mitomycin; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; C022616:thiazolyl blue