[Participation of microfilaments in the formation of adhesion plaques and their importance in cell shape and proliferative regulation].

Cell adhesion to an extracellular matrix or other suitable substrata is correlated with the formation of adhesion plaques and the bundling of microfilaments. A model of the structure of the adhesion plaque is given, considering some recent data on proteins which are involved: adhesion proteins (collagen, fibronectin, laminin etc.), receptors of adhesion proteins (e.g. integrin), components of the membrane skeleton (talin, vinculin etc.), and cytoskeletal proteins. Furthermore, the structure of microfilaments, their interaction with the membrane skeleton and other elements of the cytoskeleton as well as their role in cell flattening are discussed. Several results from literature are presented which hint at the significance of the cytoskeleton in growth regulation. From experiments on growth regulation of lens epithelial cells the following conclusion were drawn: Cell substratum contact is a precondition for the organization of microfilaments. Intact microfilaments and a rigid substratum are necessary for the development of isometric traction forces. Traction forces produced by the microfilaments alter the shape and structure of the cell nucleus and may be involved in inducing a replication competent chromatin structure.