title: Analysis of the relationships between ATM and the Rad54 paralogs involved in homologous recombination repair.
abstract: Ataxia-telangiectasia is a pleiotropic genomic instability disorder caused by lack or inactivation of the ATM protein kinase and characterized by progressive ataxia, immunodeficiency, ionizing radiation sensitivity and cancer predisposition. ATM mobilizes the cellular response to DNA double strand breaks by phosphorylating key players in this response. Double strand breaks are repaired by either nonhomologous end-joining or homologous recombination (HR) in which the Rad54 and Rad54B paralogs function. Here, we investigated the functional relationships between Atm and the Rad54 proteins by constructing compound genotypes in mice. Mouse strains were generated that combined inactivation of the Atm, Rad54 and Rad54B genes. All mutant genotypes were viable, but obtained at sub-Mendelian ratios. Double mutants for Atm and each Rad54 paralog exhibited reduced body weight and shorter lifespan, but no distinct neurological phenotype. Concomitant inactivation of ATM and Rad54 did not increase IR sensitivity; however, the triple Atm/Rad54/Rad54B mutant exhibited a significant IR hypersensitivity compared to the other genotypes. Interestingly, Atm-/- animals also exhibited hypersensitivity to the crosslinking agent mitomycin C, which was increased by deficiency of either one of the Rad54 paralogs. Our results reveal a differential interaction of the ATM-mediated DNA damage response and Rad54 paralog-mediated HR depending on the DNA damaging agent that initiates the response.
authors.affiliation: Department of Neurobiology, George S. Wise, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Michal
authors.initials: M
authors.lastname: Kirshner
authors.forename: Moran
authors.initials: M
authors.lastname: Rathavs
authors.forename: Anat
authors.initials: A
authors.lastname: Nizan
authors.forename: Jeroen
authors.initials: J
authors.lastname: Essers
authors.forename: Roland
authors.initials: R
authors.lastname: Kanaar
authors.forename: Yosef
authors.initials: Y
authors.lastname: Shiloh
authors.forename: Ari
authors.initials: A
authors.lastname: Barzilai
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D004265:DNA Helicases; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000378:metabolism*; D005838:Genotype; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008136:Longevity / Q000187:drug effects / Q000528:radiation effects; D051379:Mice; D018345:Mice, Knockout; D016685:Mitomycin / Q000633:toxicity; D009687:Nuclear Proteins / Q000378:metabolism*; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000378:metabolism*; D051135:Rad51 Recombinase / Q000378:metabolism; D011836:Radiation Tolerance / Q000187:drug effects / Q000528:radiation effects; D011839:Radiation, Ionizing; D011995:Recombination, Genetic / Q000187:drug effects / Q000528:radiation effects; D017386:Sequence Homology, Amino Acid; D016019:Survival Analysis; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000378:metabolism*; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; C498302:Trp53bp1 protein, mouse; D025521:Tumor Suppressor Proteins; D000071857:Tumor Suppressor p53-Binding Protein 1; D016685:Mitomycin; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D051135:Rad51 Recombinase; C495154:Rad51 protein, mouse; D004265:DNA Helicases; C103534:Rad54l protein, mouse