The N-terminal DH-PH domain of Trio induces cell spreading and migration by regulating lamellipodia dynamics in a Rac1-dependent fashion

PLoS One. 2012;7(1):e29912. doi: 10.1371/journal.pone.0029912. Epub 2012 Jan 6.


The guanine-nucleotide exchange factor Trio encodes two DH-PH domains that catalyze nucleotide exchange on Rac1, RhoG and RhoA. The N-terminal DH-PH domain is known to activate Rac1 and RhoG, whereas the C-terminal DH-PH domain can activate RhoA. The current study shows that the N-terminal DH-PH domain, upon expression in HeLa cells, activates Rac1 and RhoG independently from each other. In addition, we show that the flanking SH3 domain binds to the proline-rich region of the C-terminus of Rac1, but not of RhoG. However, this SH3 domain is not required for Rac1 or RhoG GDP-GTP exchange. Rescue experiments in Trio-shRNA-expressing cells showed that the N-terminal DH-PH domain of Trio, but not the C-terminal DH-PH domain, restored fibronectin-mediated cell spreading and migration defects that are observed in Trio-silenced cells. Kymograph analysis revealed that the N-terminal DH-PH domain, independent of its SH3 domain, controls the dynamics of lamellipodia. Using siRNA against Rac1 or RhoG, we found that Trio-D1-induced lamellipodia formation required Rac1 but not RhoG expression. Together, we conclude that the GEF Trio is responsible for lamellipodia formation through its N-terminal DH-PH domain in a Rac1-dependent manner during fibronectin-mediated spreading and migration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Adhesion / drug effects
  • Cell Adhesion / genetics
  • Cell Adhesion / physiology
  • Cell Movement / drug effects
  • Cell Movement / genetics*
  • Cell Movement / physiology
  • Fibronectins / pharmacology
  • Gene Expression Regulation, Neoplastic / drug effects
  • Guanine Nucleotide Exchange Factors / antagonists & inhibitors
  • Guanine Nucleotide Exchange Factors / chemistry*
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / physiology*
  • HeLa Cells
  • Humans
  • Kinetics
  • Microscopy, Electron, Scanning
  • Microscopy, Fluorescence
  • Protein Interaction Domains and Motifs / genetics
  • Protein Interaction Domains and Motifs / physiology*
  • Protein Serine-Threonine Kinases / antagonists & inhibitors
  • Protein Serine-Threonine Kinases / chemistry*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / physiology*
  • Pseudopodia / drug effects
  • Pseudopodia / genetics
  • Pseudopodia / metabolism*
  • RNA, Small Interfering / pharmacology
  • rac1 GTP-Binding Protein / genetics
  • rac1 GTP-Binding Protein / metabolism
  • rac1 GTP-Binding Protein / physiology*


  • Fibronectins
  • Guanine Nucleotide Exchange Factors
  • RAC1 protein, human
  • RNA, Small Interfering
  • Protein Serine-Threonine Kinases
  • TRIO protein, human
  • rac1 GTP-Binding Protein