The Deubiquitinating Enzyme USP1 Regulates the Fanconi Anemia Pathway

Harvard University, Cambridge, Massachusetts, United States
Molecular Cell (Impact Factor: 14.02). 03/2005; 17(3):331-9. DOI: 10.1016/j.molcel.2005.01.008
Source: PubMed


Protein ubiquitination and deubiquitination are dynamic processes implicated in the regulation of numerous cellular pathways. Monoubiquitination of the Fanconi anemia (FA) protein FANCD2 appears to be critical in the repair of DNA damage because many of the proteins that are mutated in FA are required for FANCD2 ubiquitination. By screening a gene family RNAi library, we identify the deubiquitinating enzyme USP1 as a novel component of the Fanconi anemia pathway. Inhibition of USP1 leads to hyperaccumulation of monoubiquitinated FANCD2. Furthermore, USP1 physically associates with FANCD2, and the proteins colocalize in chromatin after DNA damage. Finally, analysis of crosslinker-induced chromosomal aberrations in USP1 knockdown cells suggests a role in DNA repair. We propose that USP1 deubiquitinates FANCD2 when cells exit S phase or recommence cycling after a DNA damage insult and may play a critical role in the FA pathway by recycling FANCD2.

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    • "So far, however, just several studies showed the limited understanding of the DDR roles for DUBs that mediate the processing and removal of ubiquitin . Although these DUBs have been previously suggested DDR connections (Clerici et al., 2014; Huang et al., 2006; Jacq et al., 2013; Nakada et al., 2010; Nicassio et al., 2007; Nijman et al., 2005; Nishi et al., 2014; Wiener et al., 2012), all of them were not directly involved in DNA end resection. The genetic screen in search of DUBs that are involved in DDR showed that USP4 perhaps is involved in DDR, but the detailed function and mechanism is not clear (Nishi et al., 2014). "
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    ABSTRACT: DNA end resection is a highly regulated and critical step in DNA double-stranded break (DSB) repair. In higher eukaryotes, DSB resection is initiated by the collaborative action of CtIP and the MRE11-RAD50-NBS1 (MRN) complex. Here, we find that the deubiquitylating enzyme USP4 directly participates in DSB resection and homologous recombination (HR). USP4 confers resistance to DNA damage-inducing agents. Mechanistically, USP4 interacts with CtIP and MRN via a specific, conserved region and the catalytic domain of USP4, respectively, and regulates CtIP recruitment to sites of DNA damage. We also find that USP4 autodeubiquitylation is essential for its HR functions. Collectively, our findings identify USP4 as a key regulator of DNA DSB end resection.
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    • "Polyubiquitin chains can extend from any of the seven lysine residues of ubiquitin itself, and diversity is further amplified by branching and the combinatorial possibilities of these varied linkages (Komander and Rape, 2012). These modifications are important in targeting proteins to the proteasome (Hershko et al., 1982), as well as in an expansive set of non-degradative roles: regulating DNA repair (Nijman et al., 2005), signaling, transcription (Kö hler et al., 2010;Samara et al., 2010), cell-cycle control (Teixeira and Reed, 2013), mitochondrial integrity (Bingol et al., 2014), and the generation and recycling of free ubiquitin (Turcu and Wilkinson, 2009). A large set of $95 known deubiquitinases (DUBs) comprising five families regulates specific removal of ubiquitin. "
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    ABSTRACT: Protein ubiquitination patterns are an important component of cellular signaling. The WD-repeat protein WDR48 (USP1-associated factor UAF-1) stimulates activity of ubiquitin-specific proteases USP1, USP12, and USP46. To understand how WDR48 exerts its effect on the USP scaffold, we determined structures of the ternary WDR48:USP46:ubiquitin complex. WDR48 interacts with the USP46 fingers subdomain via a relatively small, highly polar surface on the top center of the WDR48 β propeller. In addition, WDR48 has a novel ancillary domain and a C-terminal SUMO-like domain encircling the USP46-bound ubiquitin. Mutation of residues involved in the WDR48:USP46 interaction abrogated both binding and deubiquitinase activity of the complex. An analogous mutation in USP1 similarly blocked WDR48-dependent activation. Our data suggest a possible mechanism of deubiquitinase stimulation via stabilization and prolonged residence time of substrate. The unprecedented mode of interaction between the USP fingers domain and the WD-repeat β propeller serves as a prototypical example for this family of deubiquitinases.
    Full-text · Article · Sep 2015 · Structure
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    • "The deubiquitinating enzyme USP1 regulates the level of FANCD2-Ub (Nijman et al., 2005). USP1 associates with its activating factor UAF1, and the USP1-UAF1 complex removes monoubiquitin from FANCD2 to complete the repair (Cohn et al., 2007) (Fig. 1D). "
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    ABSTRACT: Genome instability, primarily caused by faulty DNA repair mechanisms, drives tumorigenesis. Therapeutic interventions that exploit deregulated DNA repair in cancer have made considerable progress by targeting tumor-specific alterations of DNA repair factors, which either induces synthetic lethality or augments the efficacy of conventional chemotherapy and radiotherapy. The study of Fanconi anemia (FA), a rare inherited blood disorder and cancer predisposition syndrome, has been instrumental in understanding the extent to which DNA repair defects contribute to tumorigenesis. The FA pathway functions to resolve blocked replication forks in response to DNA interstrand cross-links (ICLs), and accumulating knowledge of its activation by the ubiquitin-mediated signaling pathway has provided promising therapeutic opportunities for cancer treatment. Here, we discuss recent advances in our understanding of FA pathway regulation and its potential application for designing tailored therapeutics that take advantage of deregulated DNA ICL repair in cancer.
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