Unrepaired base excision repair intermediates in template DNA strands trigger replication fork collapse and PARP inhibitor sensitivity

Abstract: DNA single‐strand breaks (SSBs) disrupt DNA replication and induce chromosome breakage. However, whether SSBs induce chromosome breakage when present behind replication forks or ahead of replication forks is unclear. To address this question, we exploited an exquisite sensitivity of SSB repair‐defective human cells lacking PARP activity or XRCC1 to the thymidine analogue 5‐chloro‐2′‐deoxyuridine (CldU). We show that incubation with CldU in these cells results in chromosome breakage, sister chromatid exchange, and cytotoxicity by a mechanism that depends on the S phase activity of uracil DNA glycosylase (UNG). Importantly, we show that CldU incorporation in one cell cycle is cytotoxic only during the following cell cycle, when it is present in template DNA. In agreement with this, while UNG induces SSBs both in nascent strands behind replication forks and in template strands ahead of replication forks, only the latter trigger fork collapse and chromosome breakage. Finally, we show that BRCA‐defective cells are hypersensitive to CldU, either alone and/or in combination with PARP inhibitor, suggesting that CldU may have clinical utility.

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch

References and Relationships

• Bibliographic citation: Unrepaired base excision repair intermediates in template DNA strands trigger replication fork collapse and PARP inhibitor sensitivity ; day:26 ; month:07 ; year:2023 ; extent:19 ; The EMBO journal / European Molecular Biology Organization ; (26.07.2023) (gesamt 19)

Contributors, Places and Time

• Creator: Serrano‐Benitez, Almudena ; Wells, Sophie E. ; Drummond‐Clarke, Lylah ; Russo, Lilian C. ; Thomas, John Christopher ; Leal, Giovanna A. ; Farrow, Mark ; Edgerton, James Michael ; Balasubramanian, Shankar ; Yang, Ming ; Frezza, Christian ; Gautam, Amit ; Brazina, Jan ; Burdova, Kamila ; Hoch, Nicolas C. ; Jackson, Stephen P. ; Caldecott, Keith W.

Further information

• DOI: 10.15252/embj.2022113190
• URN: urn:nbn:de:101:1-2023072615221393340600
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 25.03.2024, 4:48 AM CET