title: Direct interaction of focal adhesion kinase with p190RhoGEF.
abstract: Focal adhesion kinase (FAK) is a protein-tyrosine kinase that associates with multiple cell surface receptors and signaling proteins through which it can modulate the activity of several intracellular signaling pathways. FAK activity can influence the formation of distinct actin cytoskeletal structures such as lamellipodia and stress fibers in part through effects on small Rho GTPases, although the molecular interconnections of these events are not well defined. Here, we report that FAK interacts with p190RhoGEF, a RhoA-specific GDP/GTP exchange factor, in neuronal cells and in brain tissue extracts by co-immunoprecipitation and co-localization analyses. Using a two-hybrid assay and deletion mutagenesis, the binding site of the FAK C-terminal focal adhesion targeting (FAT) domain was identified within the C-terminal coiled-coil domain of p190RhoGEF. Binding was independent of a LD-like binding motif within p190RhoGEF, yet FAK association was disrupted by a mutation (Leu-1034 to Ser) that weakens the helical bundle structure of the FAK FAT domain. Neuro-2a cell binding to laminin increased endogenous FAK and p190RhoGEF tyrosine phosphorylation, and co-transfection of a dominant-negative inhibitor of FAK activity, termed FRNK, inhibited lamininstimulated p190RhoGEF tyrosine phosphorylation and p21 RhoA GTP binding. Overexpression of FAK in Neuro-2a cells increased both endogenous p190RhoGEF tyrosine phosphorylation and RhoA activity, whereas these events were inhibited by FRNK co-expression. Because insulin-like growth factor 1 treatment of Neuro-2a cells increased FAK tyrosine phosphorylation and enhanced p190RhoGEF-mediated activation of RhoA, our results support the conclusion that FAK association with p190RhoGEF functions as a signaling pathway downstream of integrins and growth factor receptors to stimulate Rho activity.
authors.affiliation: Division of Neuropathology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
authors.forename: Jinbin
authors.initials: J
authors.lastname: Zhai
authors.forename: Hong
authors.initials: H
authors.lastname: Lin
authors.forename: Zhenying
authors.initials: Z
authors.lastname: Nie
authors.forename: Junhua
authors.initials: J
authors.lastname: Wu
authors.forename: Rafaela
authors.initials: R
authors.lastname: Cañete-Soler
authors.forename: William W
authors.initials: WW
authors.lastname: Schlaepfer
authors.forename: David D
authors.initials: DD
authors.lastname: Schlaepfer
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D012097:Repressor Proteins; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: C513041:Arhgap35 protein, mouse; C513042:Arhgap5 protein, mouse; D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D009687:Nuclear Proteins; D012097:Repressor Proteins; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse; D020742:rhoA GTP-Binding Protein