Poly(ADP-RIBOSE) polymerase-1 (Parp-1) antagonizes topoisomerase I-dependent recombination stimulation by P53.
PARP-1 interacts with and poly(ADP-ribosyl)ates p53 and topoisomerase I, which both participate in DNA recombination. Previously, we showed that PARP-1 downregulates homology-directed double-strand break (DSB) repair. We also discovered that, despite the well-established role of p53 as a global suppressor of error-prone recombination, p53 enhances homologous recombination (HR) at the RARalpha breakpoint cluster region (bcr) comprising topoisomerase I recognition sites. Using an SV40-based assay and isogenic cell lines differing in the p53 and PARP-1 status we demonstrate that PARP-1 counteracts HR enhancement by p53, although DNA replication was largely unaffected. When the same DNA element was integrated in an episomal recombination plasmid, both p53 and PARP-1 exerted anti-recombinogenic rather than stimulatory activities. Strikingly, with DNA substrates integrated into cellular chromosomes, enhancement of HR by p53 and antagonistic PARP-1 action was seen, very similar to the HR of viral minichromosomes. siRNA-mediated knockdown revealed the essential role of topoisomerase I in this regulatory mechanism. However, after I-SceI-meganuclease-mediated cleavage of the chromosomally integrated substrate, no topoisomerase I-dependent effects by p53 and PARP-1 were observed. Our data further indicate that PARP-1, probably through topoisomerase I interactions rather than poly(ADP-ribosyl)ation, prevents p53 from stimulating spontaneous HR on chromosomes via topoisomerase I activity.
Universitätsfrauenklinik, Prittwitzstrasse 43 D-89075 Ulm, Germany.
Cindy
C
Baumann
Gisa S
GS
Boehden
Alexander
A
Bürkle
Lisa
L
Wiesmüller
D000818:Animals; D002460:Cell Line; D033481:Chromosomes, Mammalian / Q000378:metabolism; D004260:DNA Repair; D004264:DNA Topoisomerases, Type I / Q000502:physiology; D004279:DNA, Viral / Q000096:biosynthesis; D015536:Down-Regulation; D016679:Genome, Viral; D006801:Humans; D010957:Plasmids; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D011995:Recombination, Genetic; D013539:Simian virus 40 / Q000235:genetics; D059004:Topoisomerase I Inhibitors; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors* / Q000502:physiology
D004279:DNA, Viral; D059004:Topoisomerase I Inhibitors; D016159:Tumor Suppressor Protein p53; D011065:Poly(ADP-ribose) Polymerases; D004264:DNA Topoisomerases, Type I