RIAM, an Ena/VASP and Profilin Ligand, Interacts with Rap1-GTP and Mediates Rap1-Induced Adhesion

• Main Authors: Lafuente, Esther M. (Author), Krause, Matthias (Contributor), Carman, Christopher V. (Author), Freeman, Gordon J. (Author), Berezovskaya, Alla (Author), Constantine, Erica (Author), Springer, Timothy A. (Author), Boussiotis, Vassiliki A. (Author), Gertler, Frank (Contributor), van Puijenbroek, Andre A.F.L (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Biology (Contributor)
• Format: Article
• Language: English
• Published: Elsevier, 2014-01-06T18:40:38Z.
• Subjects: Article
• Online Access: Get fulltext

The small GTPase Rap1 induces integrin-mediated adhesion and changes in the actin cytoskeleton. The mechanisms that mediate these effects of Rap1 are poorly understood. We have identified RIAM as a Rap1-GTP-interacting adaptor molecule. RIAM defines a family of adaptor molecules that contain a RA-like (Ras association) domain, a PH (pleckstrin homology) domain, and various proline-rich motifs. RIAM also interacts with Profilin and Ena/VASP proteins, molecules that regulate actin dynamics. Overexpression of RIAM induced cell spreading and lamellipodia formation, changes that require actin polymerization. In contrast, RIAM knockdown cells had reduced content of polymerized actin. RIAM overexpression also induced integrin activation and cell adhesion. RIAM knockdown displaced Rap1-GTP from the plasma membrane and abrogated Rap1-induced adhesion. Thus, RIAM links Rap1 to integrin activation and plays a role in regulating actin dynamics.
National Institutes of Health (U.S.) (Grant AI 43552)
National Institutes of Health (U.S.) (Grant AI 46584)
National Institutes of Health (U.S.) (Grant AI 41584)
National Institutes of Health (U.S.) (Grant GM68676)