title: Multiple proteins mediate IQGAP1-stimulated cell migration.
abstract: Cell migration, a highly complex physiological phenomenon that requires the co-ordinated and tightly regulated function of several proteins, is mediated by a number of signalling pathways. Elucidation of the molecular mechanisms of cell migration impacts our comprehension of numerous cell functions, ranging from development and immune surveillance to angiogenesis and metastasis. The scaffold protein IQGAP1, which binds multiple proteins and regulates their functions, promotes cell motility. Many of the IQGAP1 binding proteins have been implicated in cell migration. In this study, we employed a multifaceted strategy to identify proteins that contribute to IQGAP1-stimulated cell migration. Using specific IQGAP1 point mutant constructs, an interaction with actin was shown to be essential for IQGAP1 to increase cell migration. In contrast, eliminating the binding of Ca(2+)/calmodulin, but not Ca(2+)-free calmodulin, augmented the ability of IQGAP1 to stimulate cell migration. Consistent with these findings, selective inhibition of calmodulin function at the plasma membrane with a specific peptide inhibitor enhanced cell migration mediated by IQGAP1. Interestingly, immunofluorescence staining and confocal microscopy suggest that localization of Cdc42 at the leading edge is not necessary for maximal migration of epithelial cells. Coupled with the observations that Cdc42 and Rac1 contribute to IQGAP1-stimulated cell migration, these data suggest that IQGAP1 serves as a junction to integrate multiple signalling molecules to facilitate cell migration.
authors.affiliation: Department of Pathology, Brigham and Women's Hospital and Harvard, Medical School, Boston, MA 02115, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Mataraza
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Li
authors.forename: Ha-Won
authors.initials: HW
authors.lastname: Jeong
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Brown
authors.forename: David B
authors.initials: DB
authors.lastname: Sacks
mesh_terms: D000199:Actins / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement; D006801:Humans; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020703:ras GTPase-Activating Proteins / Q000378:metabolism*
chemical_list: D000199:Actins; D002147:Calmodulin; C101203:IQ motif containing GTPase activating protein 1; D011506:Proteins; D020703:ras GTPase-Activating Proteins; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein