Topoisomerase I poisoning results in PARP-mediated replication fork reversal.

Abstract

Topoisomerase I (Top1) releases torsional stress during DNA replication and transcription and is inhibited by camptothecin and camptothecin-derived cancer chemotherapeutics. Top1 inhibitor cytotoxicity is frequently linked to double-strand break (DSB) formation as a result of Top1 being trapped on a nicked DNA intermediate in replicating cells. Here we use yeast, mammalian cell lines and Xenopus laevis egg extracts to show that Top1 poisons rapidly induce replication-fork slowing and reversal, which can be uncoupled from DSB formation at sublethal inhibitor doses. Poly(ADP-ribose) polymerase activity, but not single-stranded break repair in general, is required for effective fork reversal and limits DSB formation. These data identify fork reversal as a means to prevent chromosome breakage upon exogenous replication stress and implicate proteins involved in fork reversal or restart as factors modulating the cytotoxicity of replication stress-inducing chemotherapeutics.

• Authors: Arnab Ray Chaudhuri, Yoshitami Hashimoto, Raquel Herrador, Kai J Neelsen, Daniele Fachinetti, Rodrigo Bermejo, Andrea Cocito, Vincenzo Costanzo, Massimo Lopes
• Journal: Nature structural & molecular biology (Nat Struct Mol Biol) Vol. 19 Issue 4 Pg. 417-23 (Mar 04 2012) ISSN: 1545-9985 [Electronic] United States
• PMID: 22388737 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Topoisomerase I Inhibitors
• DNA
• Poly(ADP-ribose) Polymerases
• DNA Topoisomerases, Type I
• Camptothecin

Topics

• Animals
• Camptothecin (pharmacology)
• Cell Line
• DNA (chemistry, metabolism)
• DNA Repair (drug effects)
• DNA Replication (drug effects)
• DNA Topoisomerases, Type I (metabolism)
• Humans
• Nucleic Acid Conformation (drug effects)
• Poly(ADP-ribose) Polymerases (metabolism)
• Saccharomyces cerevisiae (cytology, drug effects)
• Topoisomerase I Inhibitors (pharmacology)
• Xenopus laevis (metabolism)