Rac1 Recruits the Adapter Protein CMS/CD2AP to Cell-Cell Contacts |
| |
Authors: | Trynette J. van Duijn Eloise C. Anthony Paul J. Hensbergen André M. Deelder Peter L. Hordijk |
| |
Affiliation: | From the ‡Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, University of Amsterdam, 1066 CX Amsterdam and ;the §Biomolecular Mass Spectrometry Unit, Department of Parasitology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands |
| |
Abstract: | Rac1 is a member of the Rho family of small GTPases, which regulate cell adhesion and migration through their control of the actin cytoskeleton. Rho-GTPases are structurally very similar, with the exception of a hypervariable domain in the C terminus. Using peptide-based pulldown assays in combination with mass spectrometry, we previously showed that the hypervariable domain in Rac1 mediates specific protein-protein interactions. Most recently, we found that the Rac1 C terminus associates to the ubiquitously expressed adapter protein CMS/CD2AP. CD2AP is critical for the formation and maintenance of a specialized cell-cell contact between kidney podocyte foot processes, the slit diaphragm. Here, CD2AP links the cell adhesion protein nephrin to the actin cytoskeleton. In addition, CMS/CD2AP binds actin-regulating proteins, such as CAPZ and cortactin, and has been implicated in the internalization of growth factor receptors. We found that CD2AP specifically interacts with the C-terminal domain of Rac1 but not with that of other Rho family members. Efficient interaction between Rac1 and CD2AP requires both the proline-rich domain and the poly-basic region in the Rac1 C terminus, and at least two of the three N-terminal SH3 domains of CD2AP. CD2AP co-localizes with Rac1 to membrane ruffles, and small interfering RNA-based experiments showed that CD2AP links Rac1 to CAPZ and cortactin. Finally, expression of constitutive active Rac1 recruits CD2AP to cell-cell contacts in epithelial cells, where we found CD2AP to participate in the control of the epithelial barrier function. These data identify CD2AP as a novel Rac1-associated adapter protein that participates in the regulation of epithelial cell-cell contact. |
| |
Keywords: | Adaptor Proteins Cell Junctions Cell-Cell Interaction G Proteins SH3 Domains Rac1 |
|
|