USP1 Is Required for Replication Fork Protection in BRCA1-Deficient Tumors.

BRCA1-deficient tumor cells have defects in homologous-recombination repair and replication fork stability, resulting in PARP inhibitor sensitivity. Here, we demonstrate that a deubiquitinase, USP1, is upregulated in tumors with mutations in BRCA1. Knockdown or inhibition of USP1 resulted in replication fork destabilization and decreased viability of BRCA1-deficient cells, revealing a ...
synthetic lethal relationship. USP1 binds to and is stimulated by fork DNA. A truncated form of USP1, lacking its DNA-binding region, was not stimulated by DNA and failed to localize and protect replication forks. Persistence of monoubiquitinated PCNA at the replication fork was the mechanism of cell death in the absence of USP1. Taken together, USP1 exhibits DNA-mediated activation at the replication fork, protects the fork, and promotes survival in BRCA1-deficient cells. Inhibition of USP1 may be a useful treatment for a subset of PARP-inhibitor-resistant BRCA1-deficient tumors with acquired replication fork stabilization.
Mesh Terms:
Animals, BRCA1 Protein, Binding Sites, Breast Neoplasms, Cell Proliferation, Cell Survival, DNA Replication, DNA, Neoplasm, Drug Resistance, Female, Gene Expression Regulation, Neoplastic, HEK293 Cells, HeLa Cells, Humans, Mice, Nude, Mutation, Nucleic Acid Denaturation, Poly(ADP-ribose) Polymerase Inhibitors, Proliferating Cell Nuclear Antigen, Protein Binding, Ubiquitin-Specific Proteases, Ubiquitination, Uterine Cervical Neoplasms, Xenograft Model Antitumor Assays
Mol. Cell
Date: Dec. 20, 2017
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