Local phosphatidylinositol 3,4,5-trisphosphate accumulation recruits Vav2 and Vav3 to activate Rac1/Cdc42 and initiate neurite outgrowth in nerve growth factor-stimulated PC12 cells

Mol Biol Cell. 2005 May;16(5):2207-17. doi: 10.1091/mbc.e04-10-0904. Epub 2005 Feb 23.


Neurite outgrowth is an important process in the formation of neuronal networks. Rac1 and Cdc42, members of the Rho-family GTPases, positively regulate neurite extension through reorganization of the actin cytoskeleton. Here, we examine the dynamic linkage between Rac1/Cdc42 and phosphatidylinositol 3-kinase (PI3-kinase) during nerve growth factor (NGF)-induced neurite outgrowth in PC12 cells. Activity imaging using fluorescence resonance energy transfer probes showed that PI3-kinase as well as Rac1/Cdc42 was transiently activated in broad areas of the cell periphery immediately after NGF addition. Subsequently, local and repetitive activation of PI3-kinase and Rac1/Cdc42 was observed at the protruding sites. Depletion of Vav2 and Vav3 by RNA interference significantly inhibited both Rac1/Cdc42 activation and the formation of short processes leading to neurite outgrowth. At the NGF-induced protrusions, local phosphatidylinositol 3,4,5-trisphosphate accumulation recruited Vav2 and Vav3 to activate Rac1 and Cdc42, and conversely, Vav2 and Vav3 were required for the local activation of PI3-kinase. These observations demonstrated for the first time that Vav2 and Vav3 are essential constituents of the positive feedback loop that is comprised of PI3-kinase and Rac1/Cdc42 and cycles locally with morphological changes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Biological Transport, Active / drug effects
  • Cell Cycle Proteins / antagonists & inhibitors
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Feedback
  • Fluorescence Resonance Energy Transfer
  • Nerve Growth Factor / pharmacology
  • Neurites / drug effects
  • Neurites / metabolism*
  • Neurites / ultrastructure*
  • Neurons / drug effects
  • Neurons / metabolism
  • Neurons / ultrastructure
  • Oncogene Proteins / antagonists & inhibitors
  • Oncogene Proteins / genetics
  • Oncogene Proteins / metabolism*
  • PC12 Cells
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphatidylinositol Phosphates / metabolism*
  • Proto-Oncogene Proteins / antagonists & inhibitors
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-vav / antagonists & inhibitors
  • Proto-Oncogene Proteins c-vav / genetics
  • Proto-Oncogene Proteins c-vav / metabolism*
  • RNA Interference
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • SOS1 Protein / metabolism
  • Signal Transduction
  • Son of Sevenless Proteins / metabolism
  • cdc42 GTP-Binding Protein / metabolism*
  • rac1 GTP-Binding Protein / metabolism*


  • Cell Cycle Proteins
  • Oncogene Proteins
  • Phosphatidylinositol Phosphates
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-vav
  • RNA, Messenger
  • SOS1 Protein
  • Son of Sevenless Proteins
  • VAV3 protein, rat
  • Vav1 protein, rat
  • Vav2 protein, rat
  • phosphatidylinositol 3,4,5-triphosphate
  • Nerve Growth Factor
  • Phosphatidylinositol 3-Kinases
  • cdc42 GTP-Binding Protein
  • rac1 GTP-Binding Protein