Nucleic Acids Research Advance Access originally published online on August 27, 2009
Nucleic Acids Research 2009 37(19):6400-6413; doi:10.1093/nar/gkp705
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Nucleic Acids Research, 2009, Vol. 37, No. 19 6400-6413
© The Author(s) 2009. Published by Oxford University Press.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.5/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Genome Integrity, Repair and Replication |
The ERCC1/XPF endonuclease is required for completion of homologous recombination at DNA replication forks stalled by inter-strand cross-links
1The Institute for Cancer Studies, University of Sheffield, Medical School, Beech Hill Road, Sheffield S10 2RX, UK, 2Department of Genetics Microbiology and Toxicology, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden, 3Gray Institute for Radiation Oncology & Biology, University of Oxford, Oxford, OX3 7DQ, UK and 4Genetic Department, Kerman University of Medical Sciences, Medical school, Bozorgrah Emam, Kerman, 76169-14111, Iran and 5School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, USA
*To whom correspondence should be addressed. Tel: +44 1865 617 340; Fax: +44 1865 617 334; Email: thomas.helleday{at}rob.ox.ac.uk
Received April 24, 2009. Revised August 6, 2009. Accepted August 9, 2009.
Both the ERCC1-XPF complex and the proteins involved in homoIogous recombination (HR) have critical roles in inter-strand cross-link (ICL) repair. Here, we report that mitomycin C-induced lesions inhibit replication fork elongation. Furthermore, mitomycin C-induced DNA double-strand breaks (DSBs) are the result of the collapse of ICL-stalled replication forks. These are not formed through replication run off, as we show that mitomycin C or cisplatin-induced DNA lesions are not incised by global genome nucleotide excision repair (GGR). We also suggest that ICL-lesion repair is initiated either by replication or transcription, as the GGR does not incise ICL-lesions. Furthermore, we report that RAD51 foci are induced by cisplatin or mitomycin C independently of ERCC1, but that mitomycin C-induced HR measured in a reporter construct is impaired in ERCC1-defective cells. These data suggest that ERCC1–XPF plays a role in completion of HR in ICL repair. We also find no additional sensitivity to cisplatin by siRNA co-depletion of XRCC3 and ERCC1, showing that the two proteins act on the same pathway to promote survival.