Abstract

Besides its role in homologous recombination, the tumor suppressor BRCA2 protects stalled replication forks from nucleolytic degradation. Defective fork stability contributes to chemotherapeutic sensitivity of BRCA2-defective tumors by yet-elusive mechanisms. Using DNA fiber spreading and direct visualization of replication intermediates, we report that reversed replication forks are entry points for fork degradation in BRCA2-defective cells. Besides MRE11 and PTIP, we show that RAD52 promotes stalled fork degradation and chromosomal breakage in BRCA2-defective cells. Inactivation of these factors restores reversed fork frequency and chromosome integrity in BRCA2-defective cells. Conversely, impairing fork reversal prevents fork degradation, but increases chromosomal breakage, uncoupling fork protection, and chromosome stability. We propose that BRCA2 is dispensable for RAD51-mediated fork reversal, but assembles stable RAD51 nucleofilaments on regressed arms, to protect them from degradation. Our data uncover the physiopathological relevance of fork reversal and illuminate a complex interplay of homologous recombination factors in fork remodeling and stability.

Details

Title
Replication fork reversal triggers fork degradation in BRCA2-defective cells
Author
Mijic, Sofija 1 ; Zellweger, Ralph 1 ; Nagaraja Chappidi 1 ; Berti, Matteo 1 ; Jacobs, Kurt 1 ; Mutreja, Karun 1 ; Ursich, Sebastian 1 ; Chaudhuri, Arnab Ray 2 ; Nussenzweig, Andre 3 ; Janscak, Pavel 1 ; Lopes, Massimo 1 

 Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland 
 Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA; Department of Molecular Genetics, Erasmus University Medical Center, Rotterdam, The Netherlands 
 Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA 
Pages
1-11
Publication year
2017
Publication date
Oct 2017
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
1953963854
Copyright
© 2017. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.