title: The mechanisms and dynamics of (alpha)v(beta)3 integrin clustering in living cells.
abstract: During cell migration, the physical link between the extracellular substrate and the actin cytoskeleton mediated by receptors of the integrin family is constantly modified. We analyzed the mechanisms that regulate the clustering and incorporation of activated alphavbeta3 integrins into focal adhesions. Manganese (Mn2+) or mutational activation of integrins induced the formation of de novo F-actin-independent integrin clusters. These clusters recruited talin, but not other focal adhesion adapters, and overexpression of the integrin-binding head domain of talin increased clustering. Integrin clustering required immobilized ligand and was prevented by the sequestration of phosphoinositole-4,5-bisphosphate (PI(4,5)P2). Fluorescence recovery after photobleaching analysis of Mn(2+)-induced integrin clusters revealed increased integrin turnover compared with mature focal contacts, whereas stabilization of the open conformation of the integrin ectodomain by mutagenesis reduced integrin turnover in focal contacts. Thus, integrin clustering requires the formation of the ternary complex consisting of activated integrins, immobilized ligands, talin, and PI(4,5)P2. The dynamic remodeling of this ternary complex controls cell motility.
authors.affiliation: Department of Pathology and Immunlogy, Centre Medical Universitaire, 1211 Geneva 4, Switzerland.
authors.forename: Caroline
authors.initials: C
authors.lastname: Cluzel
authors.forename: Frédéric
authors.initials: F
authors.lastname: Saltel
authors.forename: Jost
authors.initials: J
authors.lastname: Lussi
authors.forename: Frédérique
authors.initials: F
authors.lastname: Paulhe
authors.forename: Beat A
authors.initials: BA
authors.lastname: Imhof
authors.forename: Bernhard
authors.initials: B
authors.lastname: Wehrle-Haller
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D006224:Cricetinae; D005786:Gene Expression Regulation / Q000187:drug effects; D039302:Integrin alphaVbeta3 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D008345:Manganese / Q000494:pharmacology; D051379:Mice; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000199:Actins; D039302:Integrin alphaVbeta3; D008024:Ligands; D019269:Phosphatidylinositol 4,5-Diphosphate; D008345:Manganese