USP1 deubiquitinase maintains phosphorylated CHK1 by limiting its DDB1-dependent degradation

Genome Instability and Carcinogenesis UPR3081 CNRS, IGC, IMM, 31 chemin Joseph Aiguier, 13402 Marseille, France.
Human Molecular Genetics (Impact Factor: 6.39). 03/2011; 20(11):2171-81. DOI: 10.1093/hmg/ddr103
Source: PubMed


The maintenance of genetic stability depends on the fine-tuned initiation and termination of pathways involved in cell cycle checkpoints and DNA repair. Here, we describe a new pathway that regulates checkpoint kinase 1 (CHK1) activity, a key element controlling both checkpoints and DNA repair. We show that the ubiquitin-specific peptidase 1 (USP1) deubiquitinase participates in the maintenance of both total and phosphorylated levels of CHK1 in response to genotoxic stress. We establish that USP1 depletion stimulates the damage-specific DNA-binding protein 1-dependent degradation of phosphorylated CHK1 in both a monoubiquitinylated Fanconi anaemia, complementation group D2 (FANCD2)-dependent and -independent manner. Our data support the existence of a circuit in which CHK1 activates checkpoints, DNA repair and proliferating cell nuclear antigen and FANCD2 monoubiquitinylation. The latter two events, in turn, switch off activated CHK1 by negative feedback inhibition, which contributes to the downregulation of the DNA damage response. This pathway, which is compromised in the cancer-prone disease Fanconi anaemia (FA), likely contributes to the hypersensitivity of cells from FA patients to DNA damage and to the clinical phenotype of the syndrome; it may also represent a pharmacological target to improve patient care and develop new cancer therapies.

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    • "ed in chromatin remodeling and DNA repair and replication ( Jones et al . , 2002 ; Xirodimas , 2008 ) , in which the FANC pathway is also involved . Inhibition of neddylation increases both CHK1 stability and the activation of the G2 / M checkpoint ( Yang et al . , 2012 ) , which are two important cellular features associated with Fanconi anemia ( Guervilly et al . , 2011 ) . Additionally , neddylation negatively regulates the transcriptional activity of NF - kB and p53 ( Abida et al . , 2007 ; Gao et al . , 2006 ; Xirodimas et al . , 2004 ) , and the activity of these transcription factors is increased in FANC - pathway - deficient cells . These findings further support the hypothesis that there is a po"
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    ABSTRACT: The aim of this study was to identify novel substrates of the FANCcore complex, which inactivation leads to the genetic disorder Fanconi anemia (FA), which associates bone marrow failure, developmental abnormalities and predisposition to cancer. Eight FANC proteins participate in the nuclear FANCcore complex, an E3 ubiquitin-ligase that monoubiquitinates FANCD2 and FANCI in response to replicative stress. Here, we used mass spectrometry to compare proteins from FANCcore complex deficient FA-A and FA-C cells to their ectopically corrected counterparts challenged with hydroxyurea, an inducer of FANCD2 monoubiquitination. FANCD2 and FANCI appear as the only targets of the FANCcore complex. We identified other proteins post-translationally modified in a FANCA- or FANCC-dependent manner. The majority of these potential targets localizes to the cell membrane. Finally, we demonstrated that (a) the chemokine receptor CXCR5 is neddylated; (b) FANCA, but not FANCC, appears to modulate CXCR5 neddylation through an unknown mechanism; (c) CXCR5 neddylation is involved in targeting the receptor to the cell membrane; and (d) CXCR5 neddylation stimulates cell migration/motility. Our work has uncovered a pathway involving FANCA in neddylation and cell motility.
    Journal of Cell Science 07/2014; 127(16). DOI:10.1242/jcs.150706 · 5.43 Impact Factor
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    • "FANC pathway downregulation or deficiency was correlated with decreased levels of p-RPA32, with decreased frequency of p-RPA32 foci and with enhanced γH2AX accumulation (Figures 3B, 3C and S3A). As previously reported [20], [21], CHK1 was hyperphosphorylated in FANC-deficient cells (Figure 3C). Thus, the deficit in RPA phosphorylation that occurs in these cells cannot merely be ascribed to a defect in ATR activity; it is more likely to represent the consequence of the presence of fewer stretches of ssDNA. "
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    PLoS ONE 01/2013; 8(1):e53693. DOI:10.1371/journal.pone.0053693 · 3.23 Impact Factor
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    • "In the lung, Tnc appears at the epithelial-mesenchymal interface during branching morphogenesis where it may promote airway branching [30], [31]. Usp1 depletion impacts the stability and phosphorylation of Chk1 which is a cell cycle regulated and DNA damage checkpoint protein [32]. Given their known biological function, the downregulated expression of these genes is consistent with our observation of impaired BASC proliferation induced by c-Myc depletion. "
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    PLoS ONE 08/2011; 6(8):e23707. DOI:10.1371/journal.pone.0023707 · 3.23 Impact Factor
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