Coincidence of actin filaments and talin is required to activate vinculin

Hui Chen, Dilshad M. Choudhury, Susan W. Craig

Research output: Contribution to journalArticlepeer-review

Abstract

Vinculin regulates cell adhesion by strengthening contacts between extracellular matrix and the cytoskeleton. Binding of the integrin ligand, talin, to the head domain of vinculin and F-actin to its tail domain is a potential mechanism for this function, but vinculin is autoinhibited by intramolecular interactions between its head and tail domain and must be activated to bind talin and actin. Because autoinhibition of vinculin occurs by synergism between two head and tail interfaces, one hypothesis is that activation could occur by two ligands that coordinately disrupt both interfaces. To test this idea we use a fluorescence resonance energy transfer probe that reports directly on activation of vinculin. Neither talin rod, VBS3 (a talin peptide that mimics a postulated activated state of talin), nor F-actin alone can activate vinculin. But in the presence of F-actin either talin rod or VBS3 induces dose-dependent activation of vinculin. The activation data are supported by solution phase binding studies, which show that talin rod or VBS3 fails to bind vinculin, whereas the same two ligands bind tightly to vinculin head domain (Kd ∼ 100 nM). These data strongly support a combinatorial mechanism of vinculin activation; moreover, they are inconsistent with a model in which talin or activated talin is sufficient to activate vinculin. Combinatorial activation implies that at cell adhesion sites vinculin is a coincidence detector awaiting simultaneous signals from talin and actin polymerization to unleash its scaffolding activity.

Original languageEnglish (US)
Pages (from-to)40389-40398
Number of pages10
JournalJournal of Biological Chemistry
Volume281
Issue number52
DOIs
StatePublished - Dec 29 2006

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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