title: BRCA2 is required for ionizing radiation-induced assembly of Rad51 complex in vivo.
abstract: Mutations in BRCA1 and BRCA2 account for the majority of familial breast cancers. Cells with mutated BRCA1 or BRCA2 are hypersensitive to ionizing radiation (IR) and exhibit defective DNA repair. Both BRCA1 and BRCA2 have been reported to bind Rad51, a protein essential for homologous recombination and the recombinational repair of DNA double-strand breaks. In normal cells, a redistribution of Rad51 protein, manifested as formation of Rad51 nuclear foci, is seen upon IR treatment. Here we demonstrate that IR-induced Rad51 foci formation is aberrant in BRCA2- but not BRCA1-deficient tumor cells. In Capan-1 cells, which do not express functional BRCA2, there was little Rad51 foci formation in response to a wide range of radiation dosages. Moreover, forced expression of a fusion protein containing green fluorescent protein and the first Rad51-binding BRC repeat of BRCA2 in cells with wild-type BRCA2 rendered them hypersensitive to IR and cisplatin and compromised IR-induced Rad51 foci formation. In HCC1937 cells, which harbor mutation of BRCA1, IR-induced Rad51 foci were readily detected. This study suggests a requirement of BRCA2 protein for the IR-induced assembly of Rad51 complex in vivo.
authors.affiliation: Department of Molecular Medicine/Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 78245, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Yuan
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
authors.forename: G
authors.initials: G
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: Song
authors.forename: G E
authors.initials: GE
authors.lastname: Tomlinson
authors.forename: E Y
authors.initials: EY
authors.lastname: Lee
mesh_terms: D000818:Animals; D019313:BRCA1 Protein / Q000172:deficiency / Q000235:genetics; D024682:BRCA2 Protein; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology; D019556:COS Cells; D002945:Cisplatin / Q000494:pharmacology; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D019398:Genes, BRCA1; D006801:Humans; D046911:Macromolecular Substances; D009363:Neoplasm Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051135:Rad51 Recombinase; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011995:Recombination, Genetic / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
chemical_list: D019313:BRCA1 Protein; D024682:BRCA2 Protein; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D009363:Neoplasm Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D002945:Cisplatin