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Dissecting Innate Immune Signaling in Viral Evasion of Cytokine Production
08:32

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Published on: March 2, 2014

Simian virus 40 large tumor antigen modulates the Raf signaling pathway

N Grammatikakis1, K Jaronczyk, A Siganou

  • 1Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.

The Journal of Biological Chemistry
|May 31, 2001
PubMed

Insights

Simian virus 40 large tumor antigen (SVLT) activates Raf kinase, a key signaling molecule. This activation may occur independently of Ras, suggesting a novel oncogenic mechanism for SVLT.

Area of Science:

  • Oncology
  • Molecular Biology
  • Virology

Background:

  • Simian virus 40 large tumor antigen (SVLT) is a known oncogene.
  • SVLT's transforming properties are linked to p53 and pRb inactivation.
  • Previous studies suggested Ras activation in SVLT-expressing cells.

Purpose of the Study:

  • To elucidate the mechanism of action of SVLT.
  • To identify additional molecular targets of SVLT.
  • To investigate the relationship between SVLT, Ras, and Raf kinase.

Main Methods:

  • Expression of SVLT in insect and mammalian cells.
  • Analysis of Raf kinase activity.
  • Use of antisense constructs to reduce Ras levels.

Main Results:

  • SVLT expression leads to increased Raf kinase activity.
  • SVLT activates Raf kinase in both insect and mammalian cell systems.
  • Raf activation by SVLT persists even when Ras levels are significantly reduced.

Conclusions:

  • Raf kinase is a direct or indirect target of SVLT.
  • SVLT activates Raf kinase through a mechanism partially independent of Ras.
  • This finding reveals a novel pathway in SVLT-mediated oncogenesis.

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