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Updated: Aug 8, 2026

Yeast As a Chassis for Developing Functional Assays to Study Human P53
14:57

Yeast As a Chassis for Developing Functional Assays to Study Human P53

Published on: August 4, 2019

Regulation of transactivation-independent proapoptotic activity of p53 by FOXO3a

Han You1, Kazuo Yamamoto, Tak Wah Mak

  • 1The Campbell Family Institute for Breast Cancer Research, University Health Network, 620 University Avenue, Suite 706, Toronto, ON, Canada M5G 2C1.

Proceedings of the National Academy of Sciences of the United States of America
|June 8, 2006
PubMed

Insights

The tumor suppressor p53 triggers cell death via non-transcriptional pathways. Activated FOXO3a induces p53-dependent apoptosis by promoting p53

Area of Science:

  • Cellular Biology
  • Molecular Biology
  • Cancer Research

Background:

  • The tumor suppressor p53 induces apoptosis through transcriptional and non-transcriptional mechanisms.
  • Regulation of p53's non-transcriptional apoptotic activity during cellular stress is not well understood.

Purpose of the Study:

  • To investigate the role of FOXO3a in regulating p53's apoptotic function, particularly its non-transcriptional activity.
  • To elucidate the mechanisms by which FOXO3a influences p53 localization and apoptotic signaling.

Main Methods:

  • Utilized cell culture models under conditions of serum starvation and expression of constitutively active FOXO3a.
  • Assessed p53 transcriptional activity, subcellular localization, and association with nuclear export machinery.
  • Investigated the requirement of PUMA and Bax in FOXO3a-mediated apoptosis.

Main Results:

  • Activated FOXO3a can inhibit p53 transcriptional activity but still induce p53-dependent apoptosis.
  • FOXO3a promotes p53 cytoplasmic accumulation by enhancing its interaction with nuclear export factors.
  • PUMA and Bax are essential for p53-dependent apoptosis, irrespective of p53's transcriptional status.

Conclusions:

  • FOXO3a plays a critical role in inducing p53-dependent apoptosis through non-transcriptional mechanisms.
  • FOXO3a modulates p53 localization, leading to cytoplasmic accumulation and subsequent cell death signaling.
  • This study reveals a novel regulatory axis where FOXO3a enhances p53's intrinsic apoptotic potential independent of transcription.

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