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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
Summary
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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