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Daxx silencing sensitizes cells to multiple apoptotic pathways

Liuh-Yow Chen1, J Don Chen

  • 1Department of Pharmacology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.

Molecular and Cellular Biology
|October 1, 2003
PubMed

Insights

Death-associated protein (Daxx) normally inhibits apoptosis. Silencing Daxx sensitizes cells to Fas and stress-induced cell death by upregulating proapoptotic gene expression.

Area of Science:

  • Cellular Biology
  • Molecular Biology
  • Apoptosis Research

Background:

  • Daxx is a nuclear protein implicated in apoptosis and transcriptional repression.
  • Daxx interacts with Fas, PML, and transcriptional repressors.
  • Daxx's role in apoptosis is debated due to conflicting overexpression and knockout study results.

Purpose of the Study:

  • To investigate the role of Daxx in Fas- and stress-induced apoptosis.
  • To explore the involvement of PML and transcriptional repression in Daxx-regulated apoptosis.

Main Methods:

  • Small interfering RNA (siRNA) was used to silence Daxx in mammalian cells.
  • Cellular responses to Fas- and stress-induced apoptosis were monitored.
  • Caspase activation, cytochrome c release, and Jun N-terminal kinase (JNK) activation were assessed.

Main Results:

  • Daxx silencing did not cause immediate cytotoxicity but strongly sensitized cells to apoptosis.
  • Apoptosis induction led to rapid degradation of endogenous Daxx.
  • PML silencing did not affect Daxx silencing-mediated apoptosis; caspase gene expression increased without Daxx.

Conclusions:

  • Daxx functions as an inhibitor of Fas and stress-mediated apoptosis.
  • Daxx likely suppresses proapoptotic gene expression independently of PML domains.
  • These findings clarify Daxx's role in regulating programmed cell death.

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