title: Purified integrin adhesion complexes exhibit actin-polymerization activity.
abstract: BACKGROUND
  Cell adhesion and motility are accomplished through a functional linkage of the extracellular matrix with the actin cytoskeleton via adhesion complexes composed of integrin receptors and associated proteins. To determine whether this linkage is attained actively or passively, we isolated integrin complexes from nonadherent hematopoietic cells and determined their influence on the polymerization of actin.
  
  
  RESULTS
  We observed that alpha(V)beta3 complexes are capable of dramatically accelerating the rate of actin assembly, resulting in actin fibers tethered at their growing ends by clustered integrins. The ability to enhance actin polymerization was dependent upon Arg-Gly-Asp-ligand-induced beta3 tyrosine phosphorylation, agonist-induced cellular activation, sequestration of Diaphanous formins, and clustering of the receptor.
  
  
  CONCLUSIONS
  These results suggest that adhesion complexes actively promote actin assembly from their cytosolic face in order to establish a mechanical linkage with the extracellular matrix.
authors.affiliation: Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 East Adams St, Syracuse, New York 13210, USA.
authors.forename: Boyd
authors.initials: B
authors.lastname: Butler
authors.forename: Chunlei
authors.initials: C
authors.lastname: Gao
authors.forename: Akos T
authors.initials: AT
authors.lastname: Mersich
authors.forename: Scott D
authors.initials: SD
authors.lastname: Blystone
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D006224:Cricetinae; D005109:Extracellular Matrix / Q000378:metabolism*; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D007700:Kinetics; D008856:Microscopy, Fluorescence; D011108:Polymers / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D000199:Actins; D015815:Cell Adhesion Molecules; D016023:Integrins; D011108:Polymers