Relationship between the organization of actin bundles and vinculin plaques.

The temporal pattern of the formation and dissolution of vinculin patches during experimental manipulation of the state of actin within the cell was studied. Cytochalasin D-induced retraction and disappearance of stress fibers is followed, with a brief delay, by the dissolution of vinculin-containing patches and the coordinated redistribution of both actin and vinculin into newly formed amorphous aggregates or foci. Recovery from cytochalasin treatment begins with a transformation of these foci into doughnut-shaped assemblies in which actin and vinculin are precisely co-localized. The emergence and growth of filament bundles is paralleled by the appearance of faint vinculin patches that gradually increase in size in parallel with the stress fibers. If stress fibers are stabilized by microinjected rhodamine-phalloidin against stimuli that normally induce a coordinated redistribution of actin and vinculin, also the vinculin patches persist. These observations indicate that treatments influencing the state of actin in the cell have corresponding effects on the stability of vinculin patches and suggest a strong interdependency of actin and vinculin organization.