Activation of p21-activated kinase 1-nuclear factor kappaB signaling by Kaposi's sarcoma-associated herpes virus G protein-coupled receptor during cellular transformation.

Abstract

Kaposi's sarcoma-associated herpes virus (KSHV) contributes to the pathogenesis of Kaposi's sarcoma and primary effusion lymphomas. KSHV encodes a G protein-coupled receptor (KSHV-GPCR) that signals constitutively and transforms NIH3T3 cells. Here, we show that KSHV-GPCR transformation requires activation of the small G protein Rac1 and its effector, the p21-activated kinase 1 (Pak1). Either transient or sustained expression of KSHV-GPCR activated both Rac1 and Pak1. Furthermore, expression of dominant-negative mutants of Rac (RacN17) or Pak1 (PakR299, Pak-PID) inhibited KSHV-GPCR-induced focus formation and growth in soft agar. We also demonstrate that signaling from Pak1 to nuclear factor-kappaB (NFkappaB) is required for cell transformation induced by KSHV-GPCR. KSHV-GPCR induced transcriptional activation by NFkappaB. This process is inhibited by the PAK-PID, whereas reciprocally, expression of constitutively active Pak1 (PakL107F) activated NFkappaB comparably to KSHV-GPCR. The Pak-PID and RacN17 inhibited the KSHV-GPCR-induced phosphorylation of inhibitor of kappaB kinase-beta and inhibitor of kappaB-alpha, implying that it is Pak1-dependent phosphorylation and subsequent destruction of the inhibitor of kappaB proteins that allows NFkappaB activation. Finally, experiments with the KSHV-GPCR inverse agonist interferon-gamma-inducible protein-10, the Galpha(i) inhibitor pertussis toxin, and an inhibitor of phosphatidylinositol 3'-kinase, wortmannin, indicate that signaling through the Galpha(i) pathway and phosphatidylinositol 3'-kinase contributes to the cell transformation and NFkappaB activation induced by the KSHV-GPCR.

• Authors: Disha Dadke, Benjamin H Fryer, Erica A Golemis, Jeffrey Field
• Journal: Cancer research (Cancer Res) Vol. 63 Issue 24 Pg. 8837-47 (Dec 15 2003) ISSN: 0008-5472 [Print] United States
• PMID: 14695200 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• NF-kappa B
• Receptors, G-Protein-Coupled
• Tumor Necrosis Factor-alpha
• PAK1 protein, human
• Pak1 protein, mouse
• Pak1 protein, rat
• Protein Serine-Threonine Kinases
• p21-Activated Kinases
• Chuk protein, mouse
• I-kappa B Kinase
• Ikbkb protein, mouse
• Ikbke protein, mouse
• cdc42 GTP-Binding Protein
• rac1 GTP-Binding Protein

Topics

• Animals
• Cell Transformation, Viral (physiology)
• Enzyme Activation
• Herpesvirus 8, Human (metabolism, physiology)
• I-kappa B Kinase
• Mice
• NF-kappa B (metabolism)
• NIH 3T3 Cells
• Phosphatidylinositol 3-Kinases (metabolism)
• Phosphorylation
• Protein Serine-Threonine Kinases (metabolism)
• Rats
• Receptors, G-Protein-Coupled (metabolism)
• Signal Transduction
• Tumor Necrosis Factor-alpha (physiology)
• cdc42 GTP-Binding Protein (metabolism)
• p21-Activated Kinases
• rac1 GTP-Binding Protein (metabolism)