Replication fork stalling in WRN-deficient cells is overcome by prompt activation of a MUS81-dependent pathway.
Failure to stabilize and properly process stalled replication forks results in chromosome instability, which is a hallmark of cancer cells and several human genetic conditions that are characterized by cancer predisposition. Loss of WRN, a RecQ-like enzyme mutated in the cancer-prone disease Werner syndrome (WS), leads to rapid accumulation of double-strand breaks (DSBs) and proliferating cell nuclear antigen removal from chromatin upon DNA replication arrest. Knockdown of the MUS81 endonuclease in WRN-deficient cells completely prevents the accumulation of DSBs after fork stalling. Also, MUS81 knockdown in WS cells results in reduced chromatin recruitment of recombination enzymes, decreased yield of sister chromatid exchanges, and reduced survival after replication arrest. Thus, we provide novel evidence that WRN is required to avoid accumulation of DSBs and fork collapse after replication perturbation, and that prompt MUS81-dependent generation of DSBs is instrumental for recovery from hydroxyurea-mediated replication arrest under such pathological conditions.
Section of Experimental and Computational Carcinogenesis, Istituto Superiore di Sanità, 00161 Rome, Italy.
Annapaola
A
Franchitto
Livia Maria
LM
Pirzio
Ennio
E
Prosperi
Orazio
O
Sapora
Margherita
M
Bignami
Pietro
P
Pichierri
D002470:Cell Survival; D002843:Chromatin / Q000378:metabolism; D002877:Chromosomes, Human / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000378:metabolism*; D015536:Down-Regulation; D004720:Endonucleases / Q000172:deficiency / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000172:deficiency* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D053484:RecQ Helicases / Q000172:deficiency* / Q000378:metabolism; D011995:Recombination, Genetic; D016196:S Phase; D014898:Werner Syndrome / Q000473:pathology*; D000071657:Werner Syndrome Helicase
D002843:Chromatin; D004268:DNA-Binding Proteins; D018809:Proliferating Cell Nuclear Antigen; D004247:DNA; D051135:Rad51 Recombinase; D004720:Endonucleases; D005090:Exodeoxyribonucleases; C498772:MUS81 protein, human; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase