Hetero-oligomerization does not compromise 'gain of function' of tumor-derived p53 mutants

Oncogene. 2002 Jan 10;21(2):176-89. doi: 10.1038/sj.onc.1205035.

Abstract

Tumor-derived p53 mutants activate transcription from promoters of various growth-related genes. We tested whether this transactivation function of the mutant protein is sufficient to induce tumorigenesis ('gain of function'). Tumor-derived mutant p53-281G transactivates the promoters of human epidermal growth factor receptor (EGFR) and human multiple drug resistance gene (MDR-1). To determine whether the C-terminal domain functions only as an oligomerization domain in mutant p53-mediated transactivation, we have replaced the tetramerization domain of p53 by a heterologous tetramerization domain; although this mutant protein formed tetramers in solution, it failed to transactivate significantly. Therefore, for successful mutant p53-mediated transactivation, sequences near the C-terminus of mutant p53 are required to perform functions in addition to tetramerization. We also demonstrate that co-expression of a deletion mutant of p53 (p53 del 1-293), which retains the p53 oligomerization domain, inhibits this transactivation. p53 del 1-293 co-immunoprecipitates with p53-281G suggesting that hetero-oligomers of p53-281G and p53 del 1-293 are defective in transactivation. We also show that a cell line stably transfected with p53-281G expresses higher levels of endogenous NF-kappaB and proliferating cell nuclear antigen (PCNA) compared to that transfected with vector alone. On co-expression, p53 del 1-293 lowered the levels of NF-kappaB and PCNA in p53-281G-expressing cells. However, on co-expression, p53 del 1-293 did not inhibit the tumorigenicity and colony forming ability of p53-281G expressing cells. Our earlier work showed that a deletion of the C-terminal sequences of p53-281G overlapping the oligomerization domain obliterates 'gain of function'. Taken together, the above information suggests that the C-terminal sequences have some critical role in 'gain of function' in addition to transactivation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
  • Chloramphenicol O-Acetyltransferase / metabolism
  • Colony-Forming Units Assay
  • Genes, p53*
  • Humans
  • Macromolecular Substances
  • Mutagenesis
  • Oligonucleotide Array Sequence Analysis
  • Osteosarcoma
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sequence Deletion
  • Transcriptional Activation
  • Transfection
  • Tumor Cells, Cultured
  • Tumor Suppressor Protein p53 / chemistry
  • Tumor Suppressor Protein p53 / genetics*

Substances

  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Macromolecular Substances
  • Recombinant Proteins
  • Tumor Suppressor Protein p53
  • Chloramphenicol O-Acetyltransferase