title: RhoG activates Rac1 by direct interaction with the Dock180-binding protein Elmo.
abstract: The small GTPase Rac has a central role in regulating the actin cytoskeleton during cell migration and axon guidance. Elmo has been identified as an upstream regulator of Rac1 that binds to and functionally cooperates with Dock180 (refs 2-4). Dock180 does not contain a conventional catalytic domain for guanine nucleotide exchange on Rac, but possesses a domain that directly binds to and specifically activates Rac1 (refs 5, 6). The small GTPase RhoG mediates several cellular morphological processes, such as neurite outgrowth in neuronal cells, through a signalling cascade that activates Rac1 (refs 7-12); however, the downstream target of RhoG and the mechanism by which RhoG regulates Rac1 activity remain unclear. Here we show that RhoG interacts directly with Elmo in a GTP-dependent manner and forms a ternary complex with Dock180 to induce activation of Rac1. The RhoG-Elmo-Dock180 pathway is required for activation of Rac1 and cell spreading mediated by integrin, as well as for neurite outgrowth induced by nerve growth factor. We conclude that RhoG activates Rac1 through Elmo and Dock180 to control cell morphology.
authors.affiliation: Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. hirokato@pharm.kyoto-u.ac.jp
authors.forename: Hironori
authors.initials: H
authors.lastname: Katoh
authors.forename: Manabu
authors.initials: M
authors.lastname: Negishi
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D048429:Cell Size / Q000187:drug effects; D005455:Fluorescent Antibody Technique; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D016023:Integrins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D020932:Nerve Growth Factor / Q000494:pharmacology; D016501:Neurites / Q000378:metabolism; D016716:PC12 Cells; D011485:Protein Binding; D021381:Protein Transport; D051381:Rats; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D020741:rho GTP-Binding Proteins
chemical_list: D002352:Carrier Proteins; C476285:Elmo2 protein, rat; D016023:Integrins; C489578:Rhog protein, rat; C075397:RHOG protein, human; D006160:Guanosine Triphosphate; D020932:Nerve Growth Factor; D020558:GTP Phosphohydrolases; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins