Characterization of sequence elements involved in p53 stability regulation reveals cell type dependence for p53 degradation.
The growth suppressive properties of the tumor suppressor protein p53 are activated upon DNA damage. The activation of p53 is reflected in increased p53 levels which are, at least in part, the result of an extended half-life of the protein. Although this suggests that stabilization of p53 is an intrinsic feature of p53 activation, the mechanisms involved in p53 degradation and stabilization are poorly understood. Here we report on the identification of an internal deletion mutant of wild-type p53, termed delta62-96, which can be stably expressed in various cell lines. This deletion mutant has a turnover rate similar to wild-type p53 and its stability is upregulated by treatment with UV light. In cell lines that express endogenous mutant or no p53, however, delta62-96 appears to be stable, strongly indicating that these cell lines have lost the ability to degrade p53. Further characterization of delta62-96 by mutational analyses defines sequence and structural requirements for p53 degradation and indicates that none of the known p53 phosphorylation sites is essential with respect to p53 stability regulation upon UV-irradiation.
Hengstermann
A
A
Deutsches Krebsforschungszentrum, Angewandte Tumorvirologie, Heidelberg, Germany.
Whitaker
N J
NJ
Zimmer
D
D
Zentgraf
H
H
Scheffner
M
M
D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D004249:DNA Damage / Q000528:radiation effects; D004268:DNA-Binding Proteins; D006207:Half-Life; D006801:Humans; D008025:Ligases / Q000378:metabolism; D051379:Mice; D009154:Mutation; D009687:Nuclear Proteins; D009856:Oncogene Proteins, Viral / Q000502:physiology; D010766:Phosphorylation; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000032:analysis; D051736:Proto-Oncogene Proteins c-mdm2; D017384:Sequence Deletion / Q000235:genetics*; D013379:Substrate Specificity; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism*; D014466:Ultraviolet Rays
D004268:DNA-Binding Proteins; C052603:E6 protein, Human papillomavirus type 18; D009687:Nuclear Proteins; D009856:Oncogene Proteins, Viral; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D014452:Ubiquitins; C497206:MDM2 protein, human; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2; D044767:Ubiquitin-Protein Ligases; D008025:Ligases