Focal contacts (FCs) mediate adhesion between many types of cell and the extracellular matrix. Within these contacts, integrins on the cell surface link extracellular matrix ligands to cytoskeletal elements, typically actin-containing microfilaments. Now, on , Daisuke Tsuruta and Jonathan Jones provide data that indicate for the first time that the vimentin intermediate filament cytoskeleton regulates FC size and stabilises cell-matrix adhesions in some endothelial cells. By using fluorescently labelled fusion proteins, the researchers show that at least 50% of integrin-β3-containing FCs are associated with vimentin intermediate filaments in live cells. Particularly large FCs assembled when endothelial cells were subjected to shear stress in a flow chamber, and these structures, which were less dynamic than those in unstressed cells, were associated with thick vimentin bundles. Conversely, when the researchers used RNA interference to reduce vimentin expression, smaller FCs formed and the cells became less adherent to the substratum.
