QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Vol. 19, Issue 4, 1693-1705, April 2008

This Article Full Text Full Text (PDF) Supplemental Materials All Versions of this Article: E07-09-0975v1 19/4/1693    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Wen, Q. Articles by Meuth, M. PubMed PubMed Citation Articles by Wen, Q. Articles by Meuth, M.

A Mutant Allele of MRE11 Found in Mismatch Repair-deficient Tumor Cells Suppresses the Cellular Response to DNA Replication Fork Stress in a Dominant Negative Manner

Qin Wen^*, Jennifer Scorah^*,, Geraldine Phear, Gary Rodgers, Sheila Rodgers, and Mark Meuth

Institute for Cancer Studies, University of Sheffield, School of Medicine and Biomedical Sciences, Sheffield S10 2RX, United Kingdom

Submitted September 28, 2007; Revised January 16, 2008; Accepted January 29, 2008
Monitoring Editor: Orna Cohen-Fix

The interaction of ataxia-telangiectasia mutated (ATM) and the Mre11/Rad50/Nbs1 (MRN) complex is critical for the response of cells to DNA double-strand breaks; however, little is known of the role of these proteins in response to DNA replication stress. Here, we report a mutant allele of MRE11 found in a colon cancer cell line that sensitizes cells to agents causing replication fork stress. The mutant Mre11 weakly interacts with Rad50 relative to wild type and shows little affinity for Nbs1. The mutant protein lacks 3'-5' exonuclease activity as a result of loss of part of the conserved nuclease domain; however, it retains binding affinity for single-stranded DNA (ssDNA), double-stranded DNA with a 3' single-strand overhang, and fork-like structures containing ssDNA regions. In cells, the mutant protein shows a time- and dose-dependent accumulation in chromatin after thymidine treatment that corresponds with increased recruitment and hyperphosphorylation of replication protein A. ATM autophosphorylation, Mre11 foci, and thymidine-induced homologous recombination are suppressed in cells expressing the mutant allele. Together, our results suggest that the mutant Mre11 suppresses the cellular response to replication stress by binding to ssDNA regions at disrupted forks and impeding replication restart in a dominant negative manner.

* These authors contributed equally to this work.

Present address: Department of Molecular Biology, Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA 92037.

Address correspondence to: Mark Meuth (m.meuth{at}sheffield.ac.uk).

Abbreviations used: ATM, ataxia-telangiectasia mutated; ATR, ATM and Rad3 related; CPT, camptothecin; dNTP, deoxyribonucleoside triphosphate; DSB, DNA double-strand break; dsDNA, double-stranded DNA; HR, homologous recombination; IR, ionizing radiation; MMR, mismatch repair; MRN, Mre11/Nbs1/Rad50; MSI, microsatellite instability; ssDNA, single-stranded DNA.