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Strategies for Tracking Anastasis, A Cell Survival Phenomenon that Reverses Apoptosis
Published on: February 16, 2015
p53 is cleaved by caspases generating fragments localizing to mitochondria
Berna S Sayan1, A Emre Sayan1, Richard A Knight1
1Medical Research Council (MRC) Toxicology Unit, Leicester LE1 9HN, United Kingdom.
The Journal of Biological Chemistry
|March 15, 2006
Summary
The tumor suppressor protein p53 has a novel, transcription-independent role in apoptosis. Activated p53 fragments translocate to mitochondria, enhancing cell death signaling.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- The p53 protein is crucial for tumor suppression, primarily through activating pro-apoptotic genes.
- Emerging evidence points to transcription-independent functions of p53 in apoptosis.
- Activated p53 has been observed to translocate to mitochondria, inducing cytochrome c release.
Purpose of the Study:
- To investigate the role of p53 cleavage in apoptosis.
- To determine if p53 fragments possess transcription-independent apoptotic functions.
- To elucidate the mechanism of p53-mediated mitochondrial dysfunction.
Main Methods:
- Analysis of p53 cleavage by caspases.
- Identification and characterization of p53 fragments.
- Assessment of p53 fragment localization and function in apoptosis.
- Mitochondrial membrane potential assays.
Main Results:
- Caspase-dependent cleavage of p53 generates four fragments.
- Two p53 fragments lack nuclear localization signals and localize to the cytosol.
- These cytosolic fragments translocate to mitochondria and induce mitochondrial membrane depolarization independently of transcriptional activity.
- This process suggests a positive feedback loop involving caspases and p53.
Conclusions:
- p53 exhibits a novel, transcription-independent apoptotic function mediated by specific fragments.
- Cytosolic p53 fragments directly induce mitochondrial dysfunction, contributing to apoptosis.
- Activated caspases cleave p53, creating a feedback loop that amplifies mitochondrial depolarization and cell death.
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