Related Experiment Videos
p53 has a direct apoptogenic role at the mitochondria
Motohiro Mihara1, Susan Erster, Alexander Zaika
1Department of Pathology, Stony Brook University, Stony Brook, NY 11794, USA.
Molecular Cell
|April 2, 2003
Summary
The tumor suppressor p53 protein can directly trigger cell death by moving to mitochondria. This mitochondrial pathway, independent of gene regulation, involves p53 binding to BclXL, promoting apoptosis.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- The tumor suppressor protein p53 (also known as TP53) plays a critical role in apoptosis, the process of programmed cell death.
- p53 induces apoptosis through both gene regulation and transcription-independent signaling pathways.
- The mechanism underlying transcription-independent apoptosis induction by p53 was previously unknown.
Purpose of the Study:
- To elucidate the mechanism of transcription-independent apoptosis induced by p53.
- To investigate the role of mitochondrial p53 in apoptosis.
- To determine if tumor-derived p53 mutants retain mitochondrial apoptotic activity.
Main Methods:
- Studied p53 translocation to mitochondria in tumor cells and in vivo in irradiated thymocytes.
- Investigated the direct interaction of p53 with mitochondrial proteins BclXL and Bcl2.
- Analyzed the effect of p53-BclXL complex formation on mitochondrial outer membrane permeabilization and cytochrome c release.
- Examined the mitochondrial apoptotic activity of tumor-derived transactivation-deficient p53 mutants.
Main Results:
- A fraction of induced p53 translocates to the mitochondria during apoptosis.
- Targeting p53 to mitochondria is sufficient to initiate apoptosis.
- p53 directly induces outer mitochondrial membrane permeabilization by forming complexes with BclXL and Bcl2, leading to cytochrome c release.
- p53 binds to BclXL via its DNA-binding domain.
- Tumor-derived transactivation-deficient p53 mutants lose the ability to interact with BclXL and promote cytochrome c release.
Conclusions:
- p53 translocation to mitochondria is a key mechanism for transcription-independent apoptosis.
- The interaction between p53 and BclXL at the mitochondria is crucial for inducing apoptosis.
- Mutations in p53 may act as "double-hits" by disabling both its transcriptional and mitochondrial apoptotic functions, contributing to cancer development.