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Groups of p53 target genes involved in specific p53 downstream effects cluster into different classes of DNA binding
Hua Qian1, Ting Wang, Louie Naumovski
1Division of Oncology, Department of Medicine, Washington University School of Medicine, 660 S Euclid Avenue, Box 8069, St Louis, Missouri, MO 63110, USA.
Abstract:
The tumor suppressor protein p53, once activated, can cause either cell cycle arrest or apoptosis through transactivation of target genes with p53 DNA binding sites (DBS). To investigate the role of p53 DBS in the regulation of this profound, yet poorly understood decision of life versus death, we systematically studied all known and potential p53 DBS. We analysed the DBS separated from surrounding promoter regions in yeast and mammalian assays with and without DNA damage. p53 efficiently utilized the DBS of MDM2 and of genes connected to cell cycle arrest, DNA repair and the death receptor pathway of apoptosis. However, p53 was unable to utilize two-thirds of the isolated DBS, a subset that included almost all DBS of apoptosis-related genes. Neither ASPP2, a p53-interacting protein reported to specifically stimulate p53 transcriptional activity on apoptosis-related promoters, nor DNA damage resulted in p53 utilization of isolated DBS of apoptosis-related genes. Thus, a major regulation of p53 activity occurs at the level of p53 DBS themselves by posing additional requirements for the successful utilization of apoptosis-related DBS.
Insights
The tumor suppressor protein p53
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- The tumor suppressor protein p53 plays a critical role in cellular responses to DNA damage.
- p53 activation leads to either cell cycle arrest or apoptosis via transactivation of target genes.
- The precise mechanisms regulating this cell fate decision remain incompletely understood.
Purpose of the Study:
- To investigate the role of p53 DNA binding sites (DBS) in regulating the p53-mediated cell fate decision.
- To systematically analyze the utilization of known and potential p53 DBS under various conditions.
Main Methods:
- Systematic analysis of p53 DBS in isolation from promoter regions.
- Utilized yeast and mammalian assays.
- Assays were performed with and without DNA damage.
Main Results:
- p53 efficiently utilized DBS from genes involved in cell cycle arrest, DNA repair, and apoptosis (e.g., MDM2).
- p53 failed to utilize approximately two-thirds of isolated DBS, including most DBS from apoptosis-related genes.
- The p53-interacting protein ASPP2 and DNA damage did not enhance p53 utilization of isolated apoptosis-related DBS.
Conclusions:
- Regulation of p53 activity occurs at the level of the p53 DBS.
- Apoptosis-related DBS impose additional requirements for successful p53 utilization.
- This suggests a critical role for DBS context in determining p53's cell fate outcome.