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The cellular protein daxx interacts with avian sarcoma virus integrase and viral DNA to repress viral transcription

James G Greger1, Richard A Katz, Alexander M Ishov

  • 1Fox Chase Cancer Center, Institute for Cancer Research, 333 Cottman Ave., Philadelphia, PA 19111-2497, USA.

Journal of Virology
|March 30, 2005
PubMed

Insights

The cellular protein Daxx interacts with avian sarcoma virus integrase and viral DNA. Daxx recruits histone deacetylases to repress viral gene expression, acting as a cellular defense mechanism.

Area of Science:

  • Virology
  • Cellular Biology
  • Immunology

Background:

  • The avian sarcoma virus (ASV) utilizes integrase (IN) for viral replication.
  • Cellular proteins can interact with viral components to influence replication.
  • The role of Daxx in viral infections is not fully understood.

Purpose of the Study:

  • To investigate the interaction between Daxx and ASV integrase (IN).
  • To determine the role of Daxx in ASV replication and gene expression.
  • To elucidate the mechanism by which Daxx might regulate viral transcription.

Main Methods:

  • Yeast two-hybrid screening to identify Daxx-IN interactions.
  • Co-immunoprecipitation to confirm Daxx-IN association post-infection.
  • Chromatin immunoprecipitation to detect Daxx-viral DNA association.
  • Analysis of ASV reporter gene expression in Daxx-null and Daxx-expressing cells.
  • Assessment of histone deacetylase (HDAC) association with viral DNA.

Main Results:

  • Daxx was identified as an ASV IN interactor.
  • Daxx associates with viral DNA, mediated by IN.
  • Daxx is not essential for early ASV replication steps like integration.
  • Viral reporter gene expression is significantly higher in Daxx-null cells.
  • Histone deacetylases (HDACs) associate with viral DNA in Daxx-complemented cells but not in Daxx-null cells.
  • Daxx protein expression is induced upon ASV infection in an interferon-like manner.

Conclusions:

  • Daxx interacts with the IN-viral DNA complex early in ASV infection.
  • Daxx may repress viral gene expression by recruiting HDACs to viral DNA.
  • This interaction represents a novel cellular antiviral mechanism that represses viral transcription.

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