Article abstract
Nature Cell Biology 11, 1315 - 1324 (2009)
Published online: 18 October 2009 | doi:10.1038/ncb1984
Topoisomerase I suppresses genomic instability by preventing interference between replication and transcription
Sandie Tuduri1,2, Laure Crabbé1, Chiara Conti3, Hélène Tourrière1, Heidi Holtgreve-Grez4, Anna Jauch4, Véronique Pantesco5, John De Vos5, Aubin Thomas1, Charles Theillet2, Yves Pommier3, Jamal Tazi6, Arnaud Coquelle2,7 & Philippe Pasero1,7
Abstract
Topoisomerase I (Top1) is a key enzyme in functioning at the interface between DNA replication, transcription and mRNA maturation. Here, we show that Top1 suppresses genomic instability in mammalian cells by preventing a conflict between transcription and DNA replication. Using DNA combing and ChIP (chromatin immunoprecipitation)-on-chip, we found that Top1-deficient cells accumulate stalled replication forks and chromosome breaks in S phase, and that breaks occur preferentially at gene-rich regions of the genome. Notably, these phenotypes were suppressed by preventing the formation of RNA–DNA hybrids (R-loops) during transcription. Moreover, these defects could be mimicked by depletion of the splicing factor ASF/SF2 (alternative splicing factor/splicing factor 2), which interacts functionally with Top1. Taken together, these data indicate that Top1 prevents replication fork collapse by suppressing the formation of R-loops in an ASF/SF2-dependent manner. We propose that interference between replication and transcription represents a major source of spontaneous replication stress, which could drive genomic instability during the early stages of tumorigenesis.
- Institute of Human Genetics CNRS UPR1142, F-34396 Montpellier, France.
- IRCM (Institut de Recherche en Cancérologie de Montpellier), INSERM U896, Université Montpellier 1, CRLC Val d'Aurelle Paul Lamarque, F-34298 Montpellier, France.
- Laboratory of Molecular Pharmacology, NIH, Bethesda, MD 20892, USA.
- Institute of Human Genetics, University Hospital Heidelberg, D-69120, Germany.
- Inserm U847; CHU Montpellier, Institut de Recherche en Biothérapie, Hôpital Saint Eloi; Université Montpellier 1, F-34000 Montpellier, France.
- Institute of Molecular Genetics, CNRS UMR5535, F-34293 Montpellier, France.
- These authors contributed equally to this work.
Correspondence to: Arnaud Coquelle2,7 e-mail: arnaud.coquelle@inserm.fr
Correspondence to: Philippe Pasero1,7 e-mail: philippe.pasero@igh.cnrs.fr
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