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Updated: Mar 8, 2026
Purification of Ubiquitinated p53 Proteins from Mammalian Cells
Published on: March 21, 2022
TBP-like Protein (TLP) Disrupts the p53-MDM2 Interaction and Induces Long-lasting p53 Activation
Ryo Maeda1, Hiroyuki Tamashiro1, Kazunori Takano1
1Department of Biology, Graduate School of Science, Chiba University, Chiba 263-8522, Japan.
Abstract:
Stress-induced activation of p53 is an essential cellular response to prevent aberrant cell proliferation and cancer development. The ubiquitin ligase MDM2 promotes p53 degradation and limits the duration of p53 activation. It remains unclear, however, how p53 persistently escapes MDM2-mediated negative control for making appropriate cell fate decisions. Here we report that TBP-like protein (TLP), a member of the TBP family, is a new regulatory factor for the p53-MDM2 interplay and thus for p53 activation. We found that TLP acts to stabilize p53 protein to ensure long-lasting p53 activation, leading to potentiation of p53-induced apoptosis and senescence after genotoxic stress. Mechanistically, TLP interferes with MDM2 binding and ubiquitination of p53. Moreover, single cell imaging analysis shows that TLP depletion accelerates MDM2-mediated nuclear export of p53. We further show that a cervical cancer-derived TLP mutant has less p53 binding ability and lacks a proliferation-repressive function. Our findings uncover a role of TLP as a competitive MDM2 blocker, proposing a novel mechanism by which p53 escapes the p53-MDM2 negative feedback loop to modulate cell fate decisions.
Insights
TBP-like protein (TLP) stabilizes the tumor suppressor p53 by blocking its degradation by MDM2. This sustained p53 activation enhances cell death and senescence, crucial for preventing cancer development.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- Stress response pathways are critical for preventing cancer.
- The p53 tumor suppressor is tightly regulated by MDM2, which targets p53 for degradation.
- Mechanisms allowing p53 to escape MDM2-mediated inhibition are not fully understood.
Purpose of the Study:
- To identify novel regulators of the p53-MDM2 interaction.
- To elucidate the role of TBP-like protein (TLP) in p53 regulation.
- To understand how sustained p53 activation influences cell fate decisions.
Main Methods:
- Western blotting to assess protein stability.
- Co-immunoprecipitation to study protein interactions.
- Single-cell imaging to analyze protein localization and dynamics.
- Analysis of a cervical cancer-derived TLP mutant.
Main Results:
- TLP stabilizes p53 protein, prolonging its activation after genotoxic stress.
- TLP inhibits MDM2 binding to p53, reducing p53 ubiquitination.
- TLP depletion accelerates MDM2-mediated nuclear export of p53.
- A TLP mutant found in cervical cancer exhibits impaired p53 binding and reduced proliferation-repressive function.
Conclusions:
- TLP acts as a competitive inhibitor of MDM2, preventing p53 degradation.
- TLP is a novel factor that allows p53 to escape negative feedback regulation by MDM2.
- TLP plays a significant role in potentiating p53-induced apoptosis and senescence, thereby suppressing aberrant cell proliferation.
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