title: The N-terminal DH-PH domain of Trio induces cell spreading and migration by regulating lamellipodia dynamics in a Rac1-dependent fashion.
abstract: 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.
authors.affiliation: Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Jos
authors.initials: J
authors.lastname: van Rijssel
authors.forename: Mark
authors.initials: M
authors.lastname: Hoogenboezem
authors.forename: Lynn
authors.initials: L
authors.lastname: Wester
authors.forename: Peter L
authors.initials: PL
authors.lastname: Hordijk
authors.forename: Jaap D
authors.initials: JD
authors.lastname: Van Buul
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D005353:Fibronectins / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020662:Guanine Nucleotide Exchange Factors / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D054730:Protein Interaction Domains and Motifs / Q000235:genetics / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D011554:Pseudopodia / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D005353:Fibronectins; D020662:Guanine Nucleotide Exchange Factors; C107953:RAC1 protein, human; D034741:RNA, Small Interfering; D017346:Protein Serine-Threonine Kinases; C099628:TRIO protein, human; D020830:rac1 GTP-Binding Protein