title: ARF promotes MDM2 degradation and stabilizes p53: ARF-INK4a locus deletion impairs both the Rb and p53 tumor suppression pathways.
abstract: The INK4a-ARF locus encodes two unrelated proteins that both function in tumor suppression. p16INK4 binds to and inhibits the activity of CDK4 and CDK6, and ARF arrests the cell cycle in a p53-dependent manner. We show here that ARF binds to MDM2 and promotes the rapid degradation of MDM2. This interaction is mediated by the exon 1beta-encoded N-terminal domain of ARF and a C-terminal region of MDM2. ARF-promoted MDM2 degradation is associated with MDM2 modification and concurrent p53 stabilization and accumulation. The functional consequence of ARF-regulated p53 levels via MDM2 proteolysis is evidenced by the ability of ectopically expressed ARF to restore a p53-imposed G1 cell cycle arrest that is otherwise abrogated by MDM2. Thus, deletion of the ARF-INK4a locus simultaneously impairs both the INK4a-cyclin D/CDK4-RB and the ARF-MDM2-p53 pathways.
authors.affiliation: Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill, 27599-3280, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Xiong
authors.forename: W G
authors.initials: WG
authors.lastname: Yarbrough
mesh_terms: D002455:Cell Division / Q000235:genetics; D005091:Exons / Q000502:physiology; D017353:Gene Deletion; D019942:Genes, p16 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D016296:Mutagenesis / Q000502:physiology; D009687:Nuclear Proteins; D011485:Protein Binding / Q000502:physiology; D011506:Proteins / Q000032:analysis / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2; D016160:Retinoblastoma Protein / Q000378:metabolism*; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53 / Q000032:analysis / Q000378:metabolism*
chemical_list: D009687:Nuclear Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D016160:Retinoblastoma Protein; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2