Poly(ADP ribose) polymerase inhibitors (PARPi) target cancer cells deficient in homology-directed repair of DNA double-strand breaks (DSBs). In preclinical models, PARPi resistance is tied to altered nucleolytic processing (resection) at the 5' ends of a DSB. For example, loss of 53BP1 or Rev7/MAD2L2/FANCV derepresses resection to drive PARPi resistance, although the mechanisms are poorly understood. Long-range resection can be catalyzed by two machineries: the exonuclease Exo1, or the combination of a RecQ helicase and Dna2. Here, we develop a single cell microscopy assay that allows the distinct phases and machineries of resection to be interrogated simultaneously in living S. pombe cells. Using this assay, we find that the 53BP1 orthologue and Rev7 specifically repress long-range resection through the RecQ helicase-dependent pathway, thereby preventing hyper-resection. These results suggest that 'rewiring' of BRCA1-deficient cells to employ an Exo1-independent hyper-resection pathway is a driver of PARPi resistance.
Raw analysis for all individual cells included in plots, complete code, and other supporting materials are publicly available on GitHub github.com/lelandbr/Leland_King_2018_eLife_Rev7_EndResection. The raw movies for representative cells presented in the figures have been uploaded to Dryad [doi:10.5061/dryad.1db5500] . The full raw datasets (all cells, all fields, all movies) are available on request from the corresponding author (firstname.lastname@example.org) as they are TBs in size.
Data from: Rev7 and 53BP1/Crb2 prevent RecQ helicase-dependent hyper-resection of DNA double-strand breaksAvailable at Dryad Digital Repository under a CC0 Public Domain Dedication.
- Bryan A Leland
- Megan C King
- Megan C King
- Bryan A Leland
- Bryan A Leland
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Stephen C Kowalczykowski, University of California, Davis, United States
© 2018, Leland et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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