title: SH3BP1, an exocyst-associated RhoGAP, inactivates Rac1 at the front to drive cell motility.
abstract: The coordination of the several pathways involved in cell motility is poorly understood. Here, we identify SH3BP1, belonging to the RhoGAP family, as a partner of the exocyst complex and establish a physical and functional link between two motility-driving pathways, the Ral/exocyst and Rac signaling pathways. We show that SH3BP1 localizes together with the exocyst to the leading edge of motile cells and that SH3BP1 regulates cell migration via its GAP activity upon Rac1. SH3BP1 loss of function induces abnormally high Rac1 activity at the front, as visualized by in vivo biosensors, and disorganized and instable protrusions, as revealed by cell morphodynamics analysis. Consistently, constitutively active Rac1 mimics the phenotype of SH3BP1 depletion: slow migration and aberrant cell morphodynamics. Our finding that SH3BP1 downregulates Rac1 at the motile-cell front indicates that Rac1 inactivation in this location, as well as its activation by GEF proteins, is a fundamental requirement for cell motility.
authors.affiliation: Institut Curie, Centre de Recherche, Paris F-75248, France. parrini@curie.fr
authors.forename: Maria Carla
authors.initials: MC
authors.lastname: Parrini
authors.forename: Amel
authors.initials: A
authors.lastname: Sadou-Dubourgnoux
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Aoki
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Kunida
authors.forename: Marco
authors.initials: M
authors.lastname: Biondini
authors.forename: Anastassia
authors.initials: A
authors.lastname: Hatzoglou
authors.forename: Patrick
authors.initials: P
authors.lastname: Poullet
authors.forename: Etienne
authors.initials: E
authors.lastname: Formstecher
authors.forename: Charles
authors.initials: C
authors.lastname: Yeaman
authors.forename: Michiyuki
authors.initials: M
authors.lastname: Matsuda
authors.forename: Carine
authors.initials: C
authors.lastname: Rossé
authors.forename: Jacques
authors.initials: J
authors.lastname: Camonis
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D015536:Down-Regulation; D004789:Enzyme Activation; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020868:Gene Silencing; D022101:Microtubule-Organizing Center / Q000502:physiology / Q000648:ultrastructure; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D020725:ral GTP-Binding Proteins / Q000235:genetics / Q000502:physiology
chemical_list: D020690:GTPase-Activating Proteins; C082190:Ralb protein, rat; C560426:Sh3bp1 protein, rat; D014157:Transcription Factors; C085379:rho GTPase-activating protein; C499134:Rac1 protein, rat; D020830:rac1 GTP-Binding Protein; D020725:ral GTP-Binding Proteins