title: Physical and functional interactions between PML and MDM2.
abstract: The tumor suppressor protein PML and oncoprotein MDM2 have opposing effects on p53. PML stimulates p53 activity by recruiting it to nuclear foci termed PML nuclear bodies. In contrast, MDM2 inhibits p53 by promoting its degradation. To date, neither a physical nor functional relationship between PML and MDM2 has been described. In this study, we report an in vivo and in vitro interaction between PML and MDM2 which is independent of p53. Two separate regions of PML are recognized which can interact with MDM2. The C-terminal half of PML, encoded by residues 300-633, can interact with the central region of MDM2 which includes the MDM2 acidic domain. In addition, PML amino acids 1-200, which encode the RING-finger and most of the B box zinc binding motifs, can interact with the C-terminal, RING-finger containing region of MDM2. Interestingly, PML mutants in which sumoylation at lysine 160 was inhibited displayed an increased association with MDM2, suggesting that sumoylation at this site may be a determinant of PML-MDM2 binding. Coexpression with MDM2 caused a redistribution of PML from the nucleus to the cytoplasm, and this required the PML N terminus and the MDM2 RING-finger domain. These results suggest that interaction between the PML N terminus and MDM2 C terminus can promote PML nuclear exclusion. Wild-type MDM2 inhibited the ability of PML to stimulate the transcriptional activity of a GAL4-CBP fusion protein. This inhibition required the central, acidic region of MDM2, but did not require the MDM2 C terminus. Taken together, these studies demonstrate that MDM2 and PML can interact through at least two separate protein regions, and that these interactions can have specific effects on the activity and/or localization of PML.
authors.affiliation: Department of Radiation Oncology, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Wei
authors.forename: Zhong Kang
authors.initials: ZK
authors.lastname: Yu
authors.forename: Arivudainambi
authors.initials: A
authors.lastname: Ramalingam
authors.forename: Steven R
authors.initials: SR
authors.lastname: Grossman
authors.forename: Jiang H
authors.initials: JH
authors.lastname: Yu
authors.forename: Donald B
authors.initials: DB
authors.lastname: Bloch
authors.forename: Carl G
authors.initials: CG
authors.lastname: Maki
mesh_terms: D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D003001:Cloning, Molecular; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics; D004268:DNA-Binding Proteins; D005455:Fluorescent Antibody Technique; D017353:Gene Deletion; D015870:Gene Expression; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007163:Immunosorbent Techniques; D007371:Interferon-gamma / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D016296:Mutagenesis; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins; D012516:Osteosarcoma; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D016133:Polymerase Chain Reaction; D000071156:Promyelocytic Leukemia Protein; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D018411:Spodoptera / Q000378:metabolism; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000235:genetics; D025521:Tumor Suppressor Proteins
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; C052130:GAL4 protein, S cerevisiae; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; C513293:Pml protein, mouse; D000071156:Promyelocytic Leukemia Protein; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C070576:PML protein, human; D007371:Interferon-gamma; C497206:MDM2 protein, human; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2; D005982:Glutathione Transferase