title: DNA polymerase β-dependent cell survival independent of XRCC1 expression.
abstract: Base excision repair (BER) is a primary mechanism for repair of base lesions in DNA such as those formed by exposure to the DNA methylating agent methyl methanesulfonate (MMS). Both DNA polymerase β (pol β)- and XRCC1-deficient mouse fibroblasts are hypersensitive to MMS. This is linked to a repair deficiency as measured by accumulation of strand breaks and poly(ADP-ribose) (PAR). The interaction between pol β and XRCC1 is important for recruitment of pol β to sites of DNA damage. Endogenous DNA damage can substitute for MMS-induced damage such that BER deficiency as a result of either pol β- or XRCC1-deletion is associated with sensitivity to PARP inhibitors. Pol β shRNA was used to knock down pol β in Xrcc1(+/+) and Xrcc1(-/-) mouse fibroblasts. We determined whether pol β-mediated cellular resistance to MMS and PARP inhibitors resulted entirely from coordination with XRCC1 within the same BER sub-pathway. We find evidence for pol β-dependent cell survival independent of XRCC1 expression for both types of agents. The results suggest a role for pol β-dependent, XRCC1-independent repair. PAR immunofluorescence data are consistent with the hypothesis of a decrease in repair in both pol β knock down cell variants.
authors.affiliation: Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
authors.forename: Julie K
authors.initials: JK
authors.lastname: Horton
authors.affiliation: Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
authors.forename: Natalie R
authors.initials: NR
authors.lastname: Gassman
authors.affiliation: Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
authors.forename: Brittany D
authors.initials: BD
authors.lastname: Dunigan
authors.affiliation: Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
authors.forename: Donna F
authors.initials: DF
authors.lastname: Stefanick
authors.affiliation: Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA. Electronic address: wilson5@niehs.nih.gov.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Wilson
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology; D000818:Animals; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D004247:DNA / Q000378:metabolism; D018736:DNA Adducts / Q000378:metabolism; D019951:DNA Polymerase beta / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D055785:Gene Knockdown Techniques; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D011064:Poly Adenosine Diphosphate Ribose / Q000032:analysis; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000494:pharmacology; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D000477:Alkylating Agents; D018736:DNA Adducts; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D000076105:X-ray Repair Cross Complementing Protein 1; C000619352:Xrcc1 protein, mouse; D011064:Poly Adenosine Diphosphate Ribose; D004247:DNA; D008741:Methyl Methanesulfonate; D011065:Poly(ADP-ribose) Polymerases; D019951:DNA Polymerase beta
keywords: Camptothecin; DNA polymerase β; Methyl methanesulfonate; PARP inhibitor; XRCC1