Cell contact- and shape-dependent regulation of vinculin synthesis in cultured fibroblasts.

Recent studies have demonstrated the fundamental role of cell-substrate contacts and changes in cell shape in the regulation of cell growth, motility and differentiation, but the molecular basis for these phenomena is poorly understood. Because of the involvement of cytoskeletal networks in cell morphogenesis and contact formation, it is of interest that the expression of genes encoding several cytoskeletal proteins is markedly affected by changes in cell contacts and configuration. Because most of these phenomena involve changes in the form, extent or topology of cell contacts, we sought to determine whether the expression of components directly involved in the formation of cell-cell or cell-substrate contacts is affected by the respective cellular interactions. A suitable candidate for such analysis is vinculin, a cytoskeletal protein of relative molecular mass (Mr) 130,000 (130K), which is localized in focal contacts and intercellular adherens junctions. The assembly of vinculin into a membrane-bound junctional plaque seems to be one of the earliest cellular responses to contact with exogenous substrates, leading to the subsequent local assembly of the actin-rich microfilament bundles. Here we report on the regulation of vinculin synthesis in response to environmental conditions that affect cell shape and contacts.