Suppression of p53 response by blocking p53-Mediator binding with a stapled peptide
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA796059 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR17542057.fastq.gz | Fastqsanger.gz | |||
| SRR17542058.fastq.gz | Fastqsanger.gz | |||
| SRR17542059.fastq.gz | Fastqsanger.gz | |||
| SRR17542060.fastq.gz | Fastqsanger.gz | |||
| SRR17542061.fastq.gz | Fastqsanger.gz |
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Project description:DNA-binding transcription factors (TFs) have been challenging to target with molecular probes. Many TFs function in part through interaction with Mediator; we sought to block p53 function by disrupting the p53-Mediator interaction. Through rational design and activity-based screening, we characterized a stapled peptide, with functional mimics of both p53 activation domains, that selectively disrupted p53- and Mediator-dependent transcription in vitro. This “bivalent peptide” also suppressed p53 transcriptional response in human cancer cells. Our strategy circumvents the TF and instead targets the TF-Mediator interface, with desired transcriptional outcomes. Different TFs target Mediator through different subunits, suggesting this strategy could be generalizable.
2022-04-05 | GSE193418 | GEO
Project description:DNA-binding transcription factors (TFs) have been challenging to target with molecular probes. Many TFs function in part through interaction with Mediator; we sought to block p53 function by disrupting the p53-Mediator interaction. Through rational design and activity-based screening, we characterized a stapled peptide, with functional mimics of both p53 activation domains, that selectively disrupted p53- and Mediator-dependent transcription in vitro. This “bivalent peptide” also suppressed p53 transcriptional response in human cancer cells. Our strategy circumvents the TF and instead targets the TF-Mediator interface, with desired transcriptional outcomes. Different TFs target Mediator through different subunits, suggesting this strategy could be generalizable.
2020-08-01 | GSE135870 | GEO
Project description:Suppression of p53 response by blocking p53–Mediator binding with a stapled peptide
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Project description:We and others have proposed that coactivator binding inhibitors, which block the interaction of estrogen receptor and steroid receptor coactivators, may represent a potential class of new breast cancer therapeutics. The development of coactivator binding inhibitors has been limited, however, because many of the current molecules which are active in in vitro and biochemical assays are not active in cell-based assays. Our goal in this work was to prepare a coactivator binding inhibitor active in cellular models of breast cancer. To accomplish this, we used molecular dynamics simulations to convert a high-affinity stapled peptide with poor cell permeability into R4K1, a cell-penetrating stapled peptide. R4K1 displays high binding affinity for estrogen receptor ɑ, inhibits the formation of estrogen receptor/coactivator complexes, and distributes throughout the cell with a high percentage of nuclear localization. R4K1 represses native gene transcription mediated by estrogen receptor ɑ and inhibits proliferation of estradiol-stimulated MCF-7 cells. Using RNA-Seq, we demonstrate that almost all of the effects of R4K1 on global gene transcription are estrogen receptor-associated. This chemical probe provides a significant proof-of-concept for preparing cell-permeable stapled peptide inhibitors of the estrogen receptor/coactivator interaction.
2018-01-09 | GSE108308 | GEO
Project description:The Ras-family small GTPase RAB25 is involved in numerous aspects of endosomal protein trafficking and cell polarity. Recent evidence has established a role for RAB25, as well as related RAB-family and effector proteins, in oncogenic signaling, highlighting the need for chemical probes targeting this class of proteins. Here we report the development of all-hydrocarbon stabilized peptides targeting RAB25 derived from the RAB-binding FIP-family of proteins. Relative to unmodified FIP peptides, optimized stapled peptides show markedly increased structural stability, binding affinity, cell permeability and inhibition of RAB25:FIP complex formation. RAB25 expression has been shown to promote both pro- and anti-oncogenic phenotypes in specific cellular contexts. Stapled peptide RFP14 treatment of breast and ovarian cancer cell lines, in which RAB25 is pro-oncogenic, inhibited migration and proliferation in a RAB25-dependent manner. In contrast, treatment of a triple-negative breast cancer cell line in which RAB25 is tumor suppressive augmented proliferation and migration. Gene expression (RNA Seq) profiling identified significantly altered transcripts in response to RAB25 expression in ovarian cancer cells, and treatment with the optimized stapled peptide RFP14 reversed this expression profile. These data validate first-in-class chemical probes targeting RAB-family proteins and support the role of RAB25 in regulating context-specific oncogenic phenotypes.
2017-07-18 | GSE101528 | GEO
Project description:DNA-binding transcription factors (TFs) remain challenging to target with molecular probes. Many TFs function in part through interaction with Mediator, a 26-subunit complex that controls RNA polymerase II activity genome-wide. We sought to block p53 function by disrupting the p53-Mediator interaction. Through rational design and activity-based screening, we characterize a stapled peptide, with functional mimics of both p53 activation domains, that blocks p53-Mediator binding and selectively inhibits p53-dependent transcription in human cells; importantly, this "bivalent" peptide has negligible impact, genome-wide, on non-p53 target genes. Our proof-of-concept strategy circumvents the TF entirely and targets the TF-Mediator interface instead, with desired functional outcomes (i.e., selective inhibition of p53 activation). Furthermore, these results demonstrate that TF activation domains represent viable starting points for Mediator-targeting molecular probes, as an alternative to large compound libraries. Different TFs bind Mediator through different subunits, suggesting this strategy could be broadly applied to selectively alter gene expression programs.
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Project description:A cell-permeable stapled peptide inhibitor of the estrogen receptor/coactivator interaction
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Project description:The Mediator complex transmits activation signals from DNA bound transcription factors to the core transcription machinery. Genome wide localization studies have demonstrated that Mediator occupancy not only correlates with high levels of transcription, but that the complex also is present at transcriptionally silenced locations. We provide evidence that Mediator localization is guided by an interaction with histone tails, and that this interaction is regulated by their post-translational modifications. A quantitative, high-density genetic interaction map revealed links between Mediator components and factors affecting chromatin structure, especially histone deacetylases. Peptide binding assays demonstrated that pure wild type Mediator forms stable complexes with the tails of Histone H3 and H4. These binding assays also showed Mediator – histone H4 peptide interactions are specifically inhibited by acetylation of the histone H4 lysine 16, a residue critical in transcriptional silencing. Finally, these findings were validated by tiling array analysis, that revealed a broad correlation between Mediator and nucleosome occupancy in vivo, but a negative correlation between Mediator and nucleosomes acetylated at histone H4 lysine 16. Our studies show that chromatin structure and the acetylation state of histones are intimately connected to Mediator localization. Med8-TAP strain ChIPed with IgG beads vs. Input in Saccharomyces cerevisiae
2011-11-22 | E-GEOD-28613 | biostudies-arrayexpress
Project description:The tumor suppressor p53 is a key mediator of cellular stress and DNA damage response cascades and is activated after exposure to ionizing radiation. Amplifying wild-type p53 expression by targeting negative regulators such as MDM2 in combination with external beam radiotherapy (EBRT) may result in increased therapeutic effects. The novel stapled peptide PM2 prevents MDM2 from suppressing wild-type p53, and is thus a promising agent for therapeutic combination with EBRT. Effects of PM2 and potential PM2-induced radiosensitivity were assessed in a panel of cancer cell lines using 2D cell viability assays. Western Blot and flow cytometric analyses were used to investigate the mechanisms behind the observed effects in samples treated with PM2 and EBRT. Finally, PM2-treatment combined with EBRT was evaluated in an in vitro 3D spheroid model. PM2-therapy decreased cell viability in wild-type p53, HPV-negative cell lines. Western Blotting and flow cytometry confirmed upregulation of p53, as well as initiation of p53-mediated apoptosis measured by increased cleaved caspase-3 and Noxa activity. Furthermore, 3D in vitro tumor spheroid experiments confirmed the superior effects of the combination, as the only treatment regime resulting in growth inhibition and complete spheroid disintegration. We conclude that PM2 induces antitumorigenic effects in wt p53 HPV-negative cancer cells and potentiates the effects of EBRT, ultimately resulting in tumor eradication in a 3D spheroid model. This strategy shows great potential as a new wt p53 specific tumor-targeting compound, and the combination of PM2 and EBRT could be a promising strategy to increase therapeutic effects and decrease adverse effects from radiotherapy.
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