title: Modification of MDMX by sumoylation.
abstract: MDMX is a homolog of MDM2 and is critical for regulating p53 function during mouse development. MDMX level is regulated by MDM2-mediated poly-ubiquitination, which results in its accelerated degradation after DNA damage or expression of ARF. In this report, we demonstrate that MDMX can be modified by conjugation to SUMO-1 both in vivo and in vitro. We found that double mutation of two lysine residues, K254 and K379, abrogated MDMX sumoylation in vivo. Experiments using the sumoylation-deficient MDMX mutant showed that it undergoes normal ubiquitination and degradation by MDM2, normal nuclear translocation and degradation after DNA damage, and inhibits p53 with wild type efficiency. Therefore, sumoylation is not required for several activities of MDMX under our assay conditions.
authors.affiliation: Molecular Oncology Program, H. Lee Moffitt Comprehensive Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Pan
authors.forename: Jiandong
authors.initials: J
authors.lastname: Chen
mesh_terms: D021581:Active Transport, Cell Nucleus; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004249:DNA Damage; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D025842:SUMO-1 Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D025803:Tumor Suppressor Protein p14ARF / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism
chemical_list: C417743:Cdkn2a protein, mouse; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D025842:SUMO-1 Protein; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; D025801:Ubiquitin; C497206:MDM2 protein, human; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2