Mouse SLX4 Is a Tumor Suppressor that Stimulates the Activity of the Nuclease XPF-ERCC1 in DNA Crosslink Repair

Summary

SLX4 binds to three nucleases (XPF-ERCC1, MUS81-EME1, and SLX1), and its deficiency leads to genomic instability, sensitivity to DNA crosslinking agents, and Fanconi anemia. However, it is not understood how SLX4 and its associated nucleases act in DNA crosslink repair. Here, we uncover consequences of mouse Slx4 deficiency and reveal its function in DNA crosslink repair. Slx4-deficient mice develop epithelial cancers and have a contracted hematopoietic stem cell pool. The N-terminal domain of SLX4 (mini-SLX4) that only binds to XPF-ERCC1 is sufficient to confer resistance to DNA crosslinking agents. Recombinant mini-SLX4 enhances XPF-ERCC1 nuclease activity up to 100-fold, directing specificity toward DNA forks. Mini-SLX4-XPF-ERCC1 also vigorously stimulates dual incisions around a DNA crosslink embedded in a synthetic replication fork, an essential step in the repair of this lesion. These observations define vertebrate SLX4 as a tumor suppressor, which activates XPF-ERCC1 nuclease specificity in DNA crosslink repair.

Graphical Abstract

Highlights

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  SLX4 suppresses tumorigenesis and contributes to the maintenance of HSPC pool in mice

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  SLX4 enhances the nuclease activity of XPF-ERCC1 up to 100-fold

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  In complex, SLX4-XPF-ERCC1 efficiently unhooks a DNA crosslink

Abstract

SLX4 interacts with multiple nucleases that can facilitate the repair of DNA interstrand crosslinks (ICLs). Hodskinson et al. assess the long-term consequences of Slx4 deficiency in mice and show that the interaction between SLX4 and XPF-ERCC1 nuclease can support ICL repair. Biochemical analysis reveals that SLX4 stimulates XPF-ERCC1 nuclease to cut replication intermediates and unhook an ICL.