Multiple interacting domains contribute to p14ARF mediated inhibition of MDM2.
The small basic protein p14ARF, encoded by one of the alternative transcripts from the human INK4A/ARF locus, interferes with MDM2-mediated ubiquitination of the p53 tumour suppressor protein. The resultant stabilization of p53 leads to increased expression of p53-regulated genes, such as MDM2 itself and the cyclin-dependent kinase inhibitor p21(CIP1). Here we relate physical interactions between p14ARF and MDM2, as determined using synthetic peptides and systematic deletions of p14ARF, with consequential effects on p53 stabilization and transcriptional activity. The data imply that the amino terminal half of p14ARF, encoded by the alternative first exon (exon 1beta) contacts MDM2 through multiple domains that can independently impede MDM2-mediated degradation of p53, provided that they are localized in the cell nucleus. As well as identifying previously unrecognized functional domains, our findings offer an explanation for the relative paucity of missense mutations in exon 1beta in human tumours.
Clark
Paula A
PA
Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 61 Lincoln's Inn Fields, UK.
Llanos
Susana
S
Peters
Gordon
G
D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism; D005091:Exons / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D010449:Peptide Mapping; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D017384:Sequence Deletion; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D025803:Tumor Suppressor Protein p14ARF / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D002352:Carrier Proteins; C415788:Mtbp protein, mouse; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2