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Walleye dermal sarcoma virus rv-cyclin inhibits NF-kappaB-dependent transcription

Sandra L Quackenbush1, Ashley Linton, Connie D Brewster

  • 1Department of Microbiology, Immunology and Pathology, Campus Delivery 1619, Colorado State University, Fort Collins, CO 80523, USA. sandra.quackenbush@colostate.edu

Virology
|January 30, 2009
PubMed

Insights

Retroviral cyclin protein (rv-cyclin) interferes with TAF9 binding, downregulating NF-kappaB transcription. This mechanism is crucial for controlling viral replication and tumor formation.

Area of Science:

  • Virology
  • Molecular Biology
  • Cancer Research

Background:

  • Retroviral cyclin protein (rv-cyclin) possesses a transcription activation domain (AD) that interacts with TATA-binding protein-associated factor 9 (TAF9).
  • This interaction is critical for regulating both the enhancement and suppression of transcription from host and viral gene promoters.
  • Negative transcriptional regulation is achieved by rv-cyclin hindering the binding of transcriptional activators to TAF9.

Purpose of the Study:

  • To investigate the mechanism by which rv-cyclin regulates transcription, particularly its interaction with TAF9.
  • To determine the effect of rv-cyclin on NF-kappaB-dependent transcription, a pathway known to involve TAF9.
  • To elucidate the role of rv-cyclin's TAF9-binding motif in modulating NF-kappaB activity.

Main Methods:

  • Analyzing the interaction between rv-cyclin's AD and TAF9.
  • Assessing the impact of rv-cyclin on NF-kappaB-dependent transcription induced by TNFalpha or MEKK1.
  • Examining the phosphorylation and nuclear translocation of NF-kappaB p65 in rv-cyclin-expressing cells.
  • Investigating the necessity of rv-cyclin's TAF9-binding motif for NF-kappaB interference.

Main Results:

  • Rv-cyclin downregulates NF-kappaB-dependent transcription, irrespective of the induction method (TNFalpha or MEKK1).
  • In cells expressing rv-cyclin, NF-kappaB p65 undergoes phosphorylation and nuclear translocation, forming heterodimers with p50.
  • The observed interference with NF-kappaB is contingent upon an intact TAF9-binding motif within rv-cyclin.
  • Rv-cyclin's interaction with TAF9 is key to its inhibitory effect on NF-kappaB.

Conclusions:

  • Rv-cyclin actively suppresses NF-kappaB-dependent transcription through its interaction with TAF9.
  • This downregulation of NF-kappaB by rv-cyclin is likely a significant factor in managing viral replication and the development of tumors.
  • Understanding this mechanism provides insights into retroviral pathogenesis and potential therapeutic targets.

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