title: The DNA repair protein NBS1 influences the base excision repair pathway.
abstract: NBS1 fulfills important functions for the maintenance of genomic stability and cellular survival. Mutations in the NBS1 (Nijmegen Breakage Syndrome 1) gene are responsible for the Nijmegen breakage syndrome (NBS) in humans. The symptoms of this disease and the phenotypes of NBS1-defective cells, especially their enhanced radiosensitivity, can be explained by an impaired DNA double-strand break-induced signaling and a disturbed repair of these DNA lesions. We now provide evidence that NBS1 is also important for cellular survival after oxidative or alkylating stress where it is required for the proper initiation of base excision repair (BER). NBS1 downregulated cells show reduced activation of poly-(adenosine diphosphate-ribose)-polymerase-1 (PARP1) following genotoxic treatment with H(2)O(2) or methyl methanesulfonate, indicating impaired processing of damaged bases by BER as PARP1 activity is stimulated by the single-strand breaks intermediately generated during this repair pathway. Furthermore, extracts of these cells have a decreased capacity for the in vitro repair of a double-stranded oligonucleotide containing either uracil or 8-oxo-7,8-dihydroguanine to trigger BER. Our data presented here highlight for the first time a functional role for NBS1 in DNA maintenance by the BER pathway.
authors.affiliation: Institute of Radiation Biology, Helmholtz Centre Munich-German Research Centre for Environmental Health, Neuherberg, Germany. daniel.sagan@helmholtz-muenchen.de
authors.forename: Daniel
authors.initials: D
authors.lastname: Sagan
authors.forename: Romy
authors.initials: R
authors.lastname: Müller
authors.forename: Carina
authors.initials: C
authors.lastname: Kröger
authors.forename: Arunee
authors.initials: A
authors.lastname: Hematulin
authors.forename: Simone
authors.initials: S
authors.lastname: Mörtl
authors.forename: Friederike
authors.initials: F
authors.lastname: Eckardt-Schupp
mesh_terms: D000478:Alkylation; D018797:Cell Cycle Proteins / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D004249:DNA Damage / Q000502:physiology*; D004260:DNA Repair / Q000502:physiology*; D042822:Genomic Instability; D006147:Guanine / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D009687:Nuclear Proteins / Q000502:physiology*; D018384:Oxidative Stress; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014498:Uracil / Q000494:pharmacology
chemical_list: D018797:Cell Cycle Proteins; C112156:NBN protein, human; D009687:Nuclear Proteins; C024829:8-hydroxyguanine; D014498:Uracil; D006147:Guanine; D008741:Methyl Methanesulfonate; D006861:Hydrogen Peroxide; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases