A homologous recombination defect affects replication-fork progression in mammalian cells.
Faithful genome transmission requires a network of pathways coordinating DNA replication to DNA repair and recombination. Here, we used molecular combing to measure the impact of homologous recombination (HR) on the velocity of DNA replication forks. We used three hamster cell lines defective in HR either by overexpression of a RAD51 dominant-negative form, or by a defect in the RAD51 paralogue XRCC2 or the breast tumor suppressor BRCA2. Irrespectively of the type or extent of HR alteration, all three cell lines exhibited a similar reduction in the rate of replication-fork progression, associated with an increase in the density of replication forks. Importantly, this phenotype was completely reversed in complemented derivatives of Xrcc2 and Brca2 mutants. These data reveal a novel role for HR, different from the reactivation of stalled replication forks, which may play an important role in genome stability and thus in tumor protection.
Daboussi
Fayza
F
UMR 217 CNRS, Institut de Radiobiologie Cellulaire et Moléculaire, 18 route du panorama, 92265, Fontenay aux Roses, Cédex, France.
Courbet
Sylvain
S
Benhamou
Simone
S
Kannouche
Patricia
P
Zdzienicka
Malgorzata Z
MZ
Debatisse
Michelle
M
Lopez
Bernard S
BS
D000818:Animals; D024682:BRCA2 Protein / Q000096:biosynthesis; D002460:Cell Line; D045744:Cell Line, Tumor; D002469:Cell Separation; D006224:Cricetinae; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D008954:Models, Biological; D008957:Models, Genetic; D051135:Rad51 Recombinase / Q000096:biosynthesis; D011995:Recombination, Genetic
D024682:BRCA2 Protein; D004268:DNA-Binding Proteins; C113187:XRCC2 protein, human; D051135:Rad51 Recombinase