Suppression of p53 response by targeting p53-Mediator binding with a stapled peptide

Area of Science:

• Molecular Biology
• Gene Regulation
• Drug Discovery

Background:

• Targeting DNA-binding transcription factors (TFs) with molecular probes is difficult.
• Many TFs interact with the Mediator complex to control gene transcription.
• The p53 TF plays a crucial role in cellular responses.

Purpose of the Study:

• To block p53 function by disrupting its interaction with the Mediator complex.
• To develop a selective molecular probe targeting the p53-Mediator interface.
• To demonstrate a novel strategy for inhibiting specific TF activity.

Main Methods:

• Rational design and activity-based screening of peptides.
• Characterization of a stapled peptide mimicking p53 activation domains.
• Assessing the peptide's effect on p53-dependent transcription in human cells.
• Evaluating the peptide's genome-wide impact on non-p53 target genes.

Main Results:

• A bivalent stapled peptide was identified that effectively blocks p53-Mediator binding.
• The peptide selectively inhibits p53-dependent transcription in human cells.
• The peptide demonstrated negligible impact on genome-wide non-p53 target genes.
• TF activation domains serve as viable starting points for Mediator-targeting probes.

Conclusions:

• A proof-of-concept strategy targeting the TF-Mediator interface can selectively inhibit TF function.
• This approach offers an alternative to targeting TFs directly or using large compound libraries.
• The strategy holds potential for broad application in selectively altering gene expression programs by targeting different TF-Mediator interactions.