title: PARP-1 ensures regulation of replication fork progression by homologous recombination on damaged DNA.
abstract: Poly-ADP ribose polymerase 1 (PARP-1) is activated by DNA damage and has been implicated in the repair of single-strand breaks (SSBs). Involvement of PARP-1 in other DNA damage responses remains controversial. In this study, we show that PARP-1 is required for replication fork slowing on damaged DNA. Fork progression in PARP-1(-/-) DT40 cells is not slowed down even in the presence of DNA damage induced by the topoisomerase I inhibitor camptothecin (CPT). Mammalian cells treated with a PARP inhibitor or PARP-1-specific small interfering RNAs show similar results. The expression of human PARP-1 restores fork slowing in PARP-1(-/-) DT40 cells. PARP-1 affects SSB repair, homologous recombination (HR), and nonhomologous end joining; therefore, we analyzed the effect of CPT on DT40 clones deficient in these pathways. We find that fork slowing is correlated with the proficiency of HR-mediated repair. Our data support the presence of a novel checkpoint pathway in which the initiation of HR but not DNA damage delays the fork progression.
authors.affiliation: Department of Life Science, Graduate School of Bioresources, Mie University, Tsu, Mie 514-8507, Japan. sugimura@bio.mie-u.ac.jp
authors.forename: Kazuto
authors.initials: K
authors.lastname: Sugimura
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Takebayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taguchi
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takeda
authors.forename: Katsuzumi
authors.initials: K
authors.lastname: Okumura
mesh_terms: D000818:Animals; D019556:COS Cells; D002166:Camptothecin / Q000494:pharmacology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D004249:DNA Damage / Q000235:genetics* / Q000502:physiology; D004261:DNA Replication; D006367:HeLa Cells; D006801:Humans; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic
chemical_list: C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D002166:Camptothecin