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A function in apoptosis other than transactivation inherent in the NH2-terminal domain of p53
S Theis1, J Atz, N Mueller-Lantzsch
1Department of Virology, University of the Saarland, Homburg/Saar, Germany.
Abstract:
p53-mediated programmed cell death (PMCD) often requires an intact transactivation domain of the p53 tumor suppressor and is therefore usually interpreted to rely upon the transactivation of genes. As a notable exception, murine GHFT1 cells have been documented to perish in a p53-dependent manner even in the presence of transcription inhibitor actinomycin D (Act D) and have since served as one model system for transactivation-independent apoptosis. We report here that p53 transactivation domain mutant Q22,S23 nonetheless fails to mediate apoptosis in these cells as efficiently as wild-type p53. This suggests that some function of the NH2-terminal domain other than the transactivation of genes supports PMCD of GHFT1 cells. To substantiate this suggestion, we employed a p53 whose transactivation domain had been replaced with the one of VP16, which acts through the same elements of the basal transcription machinery. Although the hybrid was fully competent for transactivation, it was impaired for the mediation of apoptosis to the same extent as mutant Q22,S23. Thus, a function of the transactivation domain other than the binding to the transcription co-activators hTAF(II)31 and 70 is required for the efficient induction of apoptosis in GHFT1 cells.
Insights
p53-mediated programmed cell death (PMCD) in GHFT1 cells requires more than just gene transactivation. A specific function of the p53 transactivation domain, beyond its role in gene transcription, is essential for efficient apoptosis induction.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- p53-mediated programmed cell death (PMCD) typically relies on the p53 tumor suppressor's transactivation domain for gene transcription.
- Murine GHFT1 cells exhibit p53-dependent apoptosis even with transcription inhibitors, serving as a model for transactivation-independent apoptosis.
Purpose of the Study:
- To investigate the role of the p53 transactivation domain in GHFT1 cell apoptosis.
- To determine if functions beyond gene transactivation by the p53 NH2-terminal domain are involved in PMCD.
Main Methods:
- Utilized p53 transactivation domain mutants (Q22,S23) in GHFT1 cells.
- Employed a hybrid p53 with a VP16 transactivation domain to assess transactivation-independent apoptosis mediation.
- Assessed apoptosis induction in the presence of transcription inhibitors.
Main Results:
- A p53 mutant (Q22,S23) showed reduced apoptosis mediation in GHFT1 cells compared to wild-type p53.
- A hybrid p53 with a VP16 transactivation domain was impaired in apoptosis mediation, similar to the mutant.
- These findings suggest a transactivation-independent function of the p53 transactivation domain is crucial for GHFT1 cell apoptosis.
Conclusions:
- The p53 transactivation domain has a role in GHFT1 cell apoptosis that is independent of its gene transactivation function.
- Efficient PMCD in GHFT1 cells requires a specific function of the p53 transactivation domain, potentially involving interactions other than with hTAF(II)31 and 70.