Abstract
DNA double-strand breaks (DSBs) pose a potent threat to genome integrity. These lesions also contribute to the efficacy of radiotherapy and many cancer chemotherapeutics. DSBs elicit a signalling cascade that modifies the chromatin surrounding the break, first by ATM-dependent phosphorylation and then by RNF8-, RNF168- and BRCA1-dependent regulatory ubiquitination. Here we report that OTUB1, a deubiquitinating enzyme, is an inhibitor of DSB-induced chromatin ubiquitination. Surprisingly, we found that OTUB1 suppresses RNF168-dependent poly-ubiquitination independently of its catalytic activity. OTUB1 does so by binding to and inhibiting UBC13 (also known as UBE2N), the cognate E2 enzyme for RNF168. This unusual mode of regulation is unlikely to be limited to UBC13 because analysis of OTUB1-associated proteins revealed that OTUB1 binds to E2s of the UBE2D and UBE2E subfamilies. Finally, OTUB1 depletion mitigates the DSB repair defect associated with defective ATM signalling, indicating that pharmacological targeting of the OTUB1-UBC13 interaction might enhance the DNA damage response.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Ataxia Telangiectasia Mutated Proteins
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Cell Cycle Proteins / antagonists & inhibitors
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Cell Cycle Proteins / metabolism
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Cell Line
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Cell Line, Tumor
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Chromatin / chemistry
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Chromatin / metabolism*
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Cysteine Endopeptidases / deficiency
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Cysteine Endopeptidases / genetics
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Cysteine Endopeptidases / metabolism*
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DNA Breaks, Double-Stranded*
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DNA Repair / physiology
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DNA-Binding Proteins / antagonists & inhibitors
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DNA-Binding Proteins / metabolism
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Deubiquitinating Enzymes
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Humans
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Protein Binding
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Protein Serine-Threonine Kinases / antagonists & inhibitors
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Protein Serine-Threonine Kinases / metabolism
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Tumor Suppressor Proteins / antagonists & inhibitors
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Tumor Suppressor Proteins / metabolism
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Ubiquitin / genetics
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Ubiquitin / metabolism
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Ubiquitin-Conjugating Enzymes / antagonists & inhibitors
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Ubiquitin-Conjugating Enzymes / metabolism
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Ubiquitin-Protein Ligases / antagonists & inhibitors
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Ubiquitin-Protein Ligases / genetics
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Ubiquitin-Protein Ligases / metabolism
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Ubiquitination / physiology*
Substances
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Cell Cycle Proteins
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Chromatin
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DNA-Binding Proteins
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Tumor Suppressor Proteins
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Ubiquitin
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UBE2N protein, human
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Ubiquitin-Conjugating Enzymes
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RNF168 protein, human
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Ubiquitin-Protein Ligases
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ATM protein, human
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Ataxia Telangiectasia Mutated Proteins
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Protein Serine-Threonine Kinases
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Deubiquitinating Enzymes
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OTUB1 protein, human
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Cysteine Endopeptidases