The Deubiquitinating Enzyme USP1 Regulates the Fanconi Anemia Pathway

Division of Molecular Carcinogenesis and Center for Biomedical Genetics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
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.

1 Follower
33 Reads
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    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.
    Moleculer Cells 07/2015; 38(8). DOI:10.14348/molcells.2015.0175 · 2.09 Impact Factor
  • Source
    • "The broken strand, if unrepaired , will generate a double strand break (DSB) during S phase; DSBs are funneled towards downstream FA/ BRCA proteins FANCN/PALB2, FANCD1/BRCA2, FANCJ/BRIP1, FANCO/RAD51C, FANCP/SLX4, and BRCA1 [Kim et al., 2011] facilitating their repair mainly through homologous recombination (HR). Finally, the FA pathway is inactivated through FANCD2 and FANCI deubiquitination by the USP1/UAF1 deubiquitinating enzyme complex [Nijman, 2005]. Other DNA damage response signals, such as checkpoint proteins ATR and CHK1, are required for the activation of the FA/BRCA pathway and arresting the cell cycle [Kee and D'Andrea, 2010]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Fanconi's anemia (FA) is a recessive disease; 16 genes are currently recognized in FA. FA proteins participate in the FA/BRCA pathway that plays a crucial role in the repair of DNA damage induced by crosslinking compounds. Hydroxyurea (HU) is an agent that induces replicative stress by inhibiting ribonucleotide reductase (RNR), which synthesizes deoxyribonucleotide triphosphates (dNTPs) necessary for DNA replication and repair. HU is known to activate the FA pathway; however, its clastogenic effects are not well characterized. We have investigated the effects of HU treatment alone or in sequential combination with mitomycin-C (MMC) on FA patient-derived lymphoblastoid cell lines from groups FA-A, B, C, D1/BRCA2, and E and on lymphocytes from two unclassified FA patients. All FA cells showed a significant increase (P < 0.05) in chromosomal aberrations following treatment with HU during the last 3 h before mitosis. Furthermore, when FA cells previously exposed to MMC were treated with HU, we observed an increase of MMC-induced DNA damage that was characterized by high occurrence of DNA breaks and a reduction in rejoined chromosomal aberrations. These findings show that exposure to HU during G2 induces chromosomal aberrations by a mechanism that is independent of its well-known role in replication fork stalling during S-phase and that HU interfered mainly with the rejoining process of DNA damage. We suggest that impaired oxidative stress response, lack of an adequate amount of dNTPs for DNA repair due to RNR inhibition, and interference with cell cycle control checkpoints underlie the clastogenic activity of HU in FA cells. Environ. Mol. Mutagen., 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
    Environmental and Molecular Mutagenesis 02/2015; 56(5). DOI:10.1002/em.21938 · 2.63 Impact Factor
  • Source
    • "Although DNA synthesis was not significantly inhibited by the addition of UbVS (Figure 2A), ICL repair was abolished (Figure 2B). Only a limited amount of repair was rescued by the addition of free ubiquitin, suggesting that turnover of ubiquitylated substrates is important for repair, even in the presence of excess ubiquitin (Nijman et al., 2005; Oestergaard et al., 2007). Consistent with this idea, addition of free ubiquitin reversed the FANCD2 ubiquitylation defect caused by UbVS, but did not restore the FANCD2 deubiquitylation that is normally observed late in the reaction (Figures S1A and S1B available online). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The tumor suppressor protein BRCA1 promotes homologous recombination (HR), a high-fidelity mechanism to repair DNA double-strand breaks (DSBs) that arise during normal replication and in response to DNA-damaging agents. Recent genetic experiments indicate that BRCA1 also performs an HR-independent function during the repair of DNA interstrand crosslinks (ICLs). Here we show that BRCA1 is required to unload the CMG helicase complex from chromatin after replication forks collide with an ICL. Eviction of the stalled helicase allows leading strands to be extended toward the ICL, followed by endonucleolytic processing of the crosslink, lesion bypass, and DSB repair. Our results identify BRCA1-dependent helicase unloading as a critical, early event in ICL repair.
    Molecular Cell 09/2014; 56(1). DOI:10.1016/j.molcel.2014.08.012 · 14.02 Impact Factor
Show more

Preview (2 Sources)

33 Reads
Available from