title: Recruitment of the Arp2/3 complex to vinculin: coupling membrane protrusion to matrix adhesion.
abstract: Cell migration involves many steps, including membrane protrusion and the development of new adhesions. Here we have investigated whether there is a link between actin polymerization and integrin engagement. In response to signals that trigger membrane protrusion, the actin-related protein (Arp)2/3 complex transiently binds to vinculin, an integrin-associated protein. The interaction is regulated, requiring phosphatidylinositol-4,5-bisphosphate and Rac1 activation, and is sufficient to recruit the Arp2/3 complex to new sites of integrin aggregation. Binding of the Arp2/3 complex to vinculin is direct and does not depend on the ability of vinculin to associate with actin. We have mapped the binding site for the Arp2/3 complex to the hinge region of vinculin, and a point mutation in this region selectively blocks binding to the Arp2/3 complex. Compared with WT vinculin, expression of this mutant in vinculin-null cells results in diminished lamellipodial protrusion and spreading on fibronectin. The recruitment of the Arp2/3 complex to vinculin may be one mechanism through which actin polymerization and membrane protrusion are coupled to integrin-mediated adhesion.
authors.affiliation: Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA. kdemali@med.unc.edu
authors.forename: Kris A
authors.initials: KA
authors.lastname: DeMali
authors.forename: Christy A
authors.initials: CA
authors.lastname: Barlow
authors.forename: Keith
authors.initials: K
authors.lastname: Burridge
mesh_terms: D016475:3T3 Cells; D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins / Q000378:metabolism; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004622:Embryo, Mammalian; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism; D005353:Fibronectins / Q000502:physiology; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D016023:Integrins / Q000378:metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017354:Point Mutation; D011485:Protein Binding; D011554:Pseudopodia / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016596:Vinculin / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000077191:Wortmannin; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins; D000730:Androstadienes; D003598:Cytoskeletal Proteins; D004815:Epidermal Growth Factor; D005353:Fibronectins; D049452:Green Fluorescent Proteins; D016023:Integrins; D008164:Luminescent Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011993:Recombinant Fusion Proteins; D016596:Vinculin; D000077191:Wortmannin; D020830:rac1 GTP-Binding Protein; C495926:ACTR2 protein, human; C495928:ACTR3 protein, human; C495927:Actr2 protein, mouse; C495929:Actr3 protein, mouse