The small GTPase R-Ras regulates organization of actin and drives membrane protrusions through the activity of PLCε

Aude S. Ada-Nguema, Harry Xenias, Michael Sheetz, Patricia J. Keely

Research output: Contribution to journalArticle

57 Scopus citations

Abstract

R-Ras, an atypical member of the Ras subfamily of small GTPases, enhances integrin-mediated adhesion and signaling through a poorly understood mechanism. Dynamic analysis of cell spreading by total internal reflection fluorescence (TIRF) microscopy demonstrated that active R-Ras lengthened the duration of initial membrane protrusion, and promoted the formation of a ruffling lamellipod, rich in branched actin structures and devoid of filopodia. By contrast, dominant-negative R-Ras enhanced filopodia formation. Moreover, RNA interference (RNAi) approaches demonstrated that endogenous R-Ras contributed to cell spreading. These observations suggest that R-Ras regulates membrane protrusions through organization of the actin cytoskeleton. Our results suggest that phospholipase Cε (PLCε) is a novel R-Ras effector mediating the effects of R-Ras on the actin cytoskeleton and membrane protrusion, because R-Ras was co-precipitated with PLCε and increased its activity. Knockdown of PLCε with siRNA reduced the formation of the ruffling lamellipod in R-Ras cells. Consistent with this pathway, inhibitors of PLC activity, or chelating intracellular Ca2+ abolished the ability of R-Ras to promote membrane protrusions and spreading. Overall, these data suggest that R-Ras signaling regulates the organization of the actin cytoskeleton to sustain membrane protrusion through the activity of PLCε.

Original languageEnglish (US)
Pages (from-to)1307-1319
Number of pages13
JournalJournal of Cell Science
Volume119
Issue number7
DOIs
StatePublished - Apr 1 2006
Externally publishedYes

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Keywords

  • Actin
  • Ca
  • Cell adhesion
  • Cell spreading
  • Integrin
  • PLC
  • R-Ras

ASJC Scopus subject areas

  • Cell Biology

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