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Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
10:27

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Published on: March 9, 2012

Vav mediates Ras stimulation by direct activation of the GDP/GTP exchange factor Ras GRP1

María J Caloca1, José L Zugaza, David Matallanas

  • 1Centro de Investigación del Cáncer, University of Salamanca-CSIC, Campus Unamuno, E-37007 Salamanca and Instituto de Investigaciones Biomédicas Alberto Sols, E-28929 Madrid, Spain.

The EMBO Journal
|July 4, 2003
PubMed

Insights

A novel cross-talk between Vav/Rac1 and Ras pathways involves RasGRP1, crucial for Ras activation in lymphoid cells. This signaling relay requires diacylglycerol generation and actin polymerization for robust cellular responses.

Area of Science:

  • Cellular signaling
  • Molecular biology
  • Immunology

Background:

  • The Ras and Vav/Rac1 pathways are critical for cellular processes.
  • Understanding cross-talk between these pathways is essential for deciphering complex cellular responses.

Purpose of the Study:

  • To elucidate a novel signaling cross-talk between the Vav/Rac1 and Ras pathways.
  • To identify the role of RasGRP1 in mediating this interaction in lymphoid cells.

Main Methods:

  • Investigated the stimulation of RasGRP1, a guanine nucleotide exchange factor for Ras.
  • Examined the requirement of diacylglycerol generation (via phospholipase C-gamma) and actin polymerization for RasGRP1 translocation and activation.
  • Utilized tyrosine-phosphorylated Vav, oncogenic Vav, and constitutively active Rac1 to study cross-talk activation.
  • Employed inhibitors of phospholipase C-gamma and F-actin polymerization to block Ras activation.

Main Results:

  • Discovered a new signaling cross-talk mediated by RasGRP1, linking Vav/Rac1 and Ras pathways.
  • Demonstrated that Vav proteins are essential for Ras activation in lymphoid cells.
  • Showed that RasGRP1 activation depends on diacylglycerol generation and actin polymerization, facilitated by Vav and Rac1.
  • Confirmed that this cross-talk can be modulated by specific Vav and Rac1 forms and blocked by relevant inhibitors.

Conclusions:

  • A novel relay mechanism exists between Rac/Rho and Ras pathways in lymphoid and other cells.
  • This cross-talk, involving RasGRP1, ensures robust signaling upon receptor engagement.
  • The findings provide new insights into the regulation of Ras signaling in immune cells.

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