title: Tumor suppressor ARF promotes non-classic proteasome-independent polyubiquitination of COMMD1.
abstract: Although the tumor suppressor ARF is generally accepted for its essential role in activating the p53 pathway, its p53-independent function has also been proposed. Here, we report that ARF associates with COMMD1 and promotes Lys(63)-mediated polyubiquitination of COMMD1 in a p53-independent manner. We found that ARF interacts with COMMD1 in vivo. Deletion analysis of ARF suggested that the N-terminal amino acids 15-45 are important for its interaction with COMMD1. In addition, we found that endogenous ARF redistributes from the nucleolus to the nucleoplasm and interacts with COMMD1 when DNA is damaged by actinomycin D. Interestingly, we found that ARF promotes the polyubiquitination of COMMD1 through Lys(63) of ubiquitin but not the polyubiquitination of Lys(48), which does not target COMMD1 for proteasome-dependent proteolysis. Moreover, ARF mutants lacking the domain interacting with COMMD1 did not promote COMMD1 polyubiquitination, indicating that physical association is a prerequisite condition for the polyubiquitination process. Together, these data suggest that the ability to promote Lys(63)-mediated polyubiquitination of COMMD1 is a novel property of ARF independent of p53.
authors.affiliation: Division of Molecular and Cell Biology, School of Biological Sciences, College of Science, Nanyang Technological University, Singapore 637551.
authors.forename: Yafen
authors.initials: Y
authors.lastname: Huang
authors.forename: Mian
authors.initials: M
authors.lastname: Wu
authors.forename: Hoi-Yeung
authors.initials: HY
authors.lastname: Li
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism*; D004249:DNA Damage; D003609:Dactinomycin / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008239:Lysine / Q000737:chemistry; D008954:Models, Biological; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C480519:COMMD1 protein, human; D002352:Carrier Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D016159:Tumor Suppressor Protein p53; D025801:Ubiquitin; D003609:Dactinomycin; D046988:Proteasome Endopeptidase Complex; D008239:Lysine