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Updated: Jun 22, 2026

Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro
13:20

Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro

Published on: July 17, 2018

MDM4 (MDMX) localizes at the mitochondria and facilitates the p53-mediated intrinsic-apoptotic pathway

Francesca Mancini1, Giusy Di Conza, Marsha Pellegrino

  • 1Institute of Neurobiology and Molecular Medicine, National Council of Research, Rome, Italy.

The EMBO Journal
|June 13, 2009
PubMed

Insights

MDM4 protein regulates p53

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • MDM4 is a known regulator of p53, influencing its transcriptional activity.
  • The cytoplasmic localization of MDM4 suggests potential roles beyond transcriptional regulation, possibly involving mitochondrial functions of p53.

Purpose of the Study:

  • To investigate the mitochondrial localization and function of MDM4.
  • To elucidate MDM4's role in p53-mediated apoptosis, particularly its transcription-independent functions.

Main Methods:

  • Immunofluorescence and cell fractionation to determine MDM4 localization.
  • Co-immunoprecipitation assays to study protein-protein interactions (MDM4, p53, BCL2).
  • RNA interference (RNAi) to reduce MDM4 expression and assess apoptosis resistance.
  • Analysis of MDM4 expression in human ovarian cancer tissues and cell lines.

Main Results:

  • MDM4 stably localizes to mitochondria.
  • In mitochondria, MDM4 binds to BCL2 and facilitates the localization of phosphorylated p53 (p53Ser46(P)).
  • MDM4 promotes the interaction between p53Ser46(P) and BCL2, leading to cytochrome C release and apoptosis.
  • MDM4 depletion enhances resistance to DNA-damage-induced apoptosis in a p53-dependent, transcription-independent manner.
  • Downregulation of MDM4 correlates with cisplatin resistance in ovarian cancer, and its modulation affects drug sensitivity.

Conclusions:

  • MDM4 has a novel mitochondrial function as a docking site for p53Ser46(P) to BCL2, promoting the intrinsic apoptotic pathway.
  • MDM4 acts as a dual regulator of p53, influencing both transcriptional and transcription-independent apoptotic functions.
  • MDM4 modulation represents a potential therapeutic strategy for enhancing chemosensitivity in ovarian cancer.

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