GRASP and IPCEF Promote ARF-to-Rac Signaling and Cell Migration by Coordinating the Association of ARNO/cytohesin 2 with Dock180

• Published in: Molecular biology of the cell Vol. 21; no. 4; pp. 562 - 571
• Main Authors: White, David T., McShea, Katie M., Attar, Myriam A., Santy, Lorraine C.
• Format: Journal Article
• Language: English
• Published: United States The American Society for Cell Biology 15.02.2010
• Subjects: ADP-Ribosylation Factors - genetics; ADP-Ribosylation Factors - metabolism; Animals; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Adhesion Molecules - genetics; Cell Adhesion Molecules - metabolism; Cell Line; Cell Movement - physiology; Dogs; Enzyme Activation; Gene Knockdown Techniques; GTPase-Activating Proteins - chemistry; GTPase-Activating Proteins - genetics; GTPase-Activating Proteins - metabolism; Humans; Membrane Proteins - genetics; Membrane Proteins - metabolism; Multiprotein Complexes - chemistry; Multiprotein Complexes - metabolism; Protein Structure, Secondary; rac GTP-Binding Proteins - genetics; rac GTP-Binding Proteins - metabolism; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; Signal Transduction - physiology
• DOI: 10.1091/mbc.e09-03-0217
• ISSN: 1059-1524; 1939-4586

ARFs are small GTPases that regulate vesicular trafficking, cell shape, and movement. ARFs are subject to extensive regulation by a large number of accessory proteins. The many different accessory proteins are likely specialized to regulate ARF signaling during particular processes. ARNO/cytohesin 2 is an ARF-activating protein that promotes cell migration and cell shape changes. We report here that protein–protein interactions mediated by the coiled-coil domain of ARNO are required for ARNO induced motility. ARNO lacking the coiled-coil domain does not promote migration and does not induce ARF-dependent Rac activation. We find that the coiled-coil domain promotes the assembly of a multiprotein complex containing both ARNO and the Rac-activating protein Dock180. Knockdown of either GRASP/Tamalin or IPCEF, two proteins known to bind to the coiled-coil of ARNO, prevents the association of ARNO and Dock180 and prevents ARNO-induced Rac activation. These data suggest that scaffold proteins can regulate ARF dependent processes by biasing ARF signaling toward particular outputs.