IDENTIFICATION OF VINCULIN AS A PERICENTRIOLAR COMPONENT IN MAMMALIAN-CELLS

Previous studies have shown that centrosome position and structure can be influenced by actin filaments, that centrosomes can influence acti n organization, and that an actin homologue is associated with centros omes. Such observations suggest the existence of connections between c entrosomes and actin networks. In keeping with such observations, we s how that the pericentriolar material, a main component of centrosomes, contains vinculin, a well-known component of cell adhesion plaques an d of adherens cell junctions. We find that in various cell types, cent rosomes are specifically stained by five different anti-vinculin antib odies, In adherent cell lines, these antibodies also stained adhesion plaques, but in thymocytes, a cell type devoid of adhesive structures, such antibodies stained only centrosomes. Isolated centrosomes also r eacted with the anti-vinculin antibodies and immuno-electron microscop y showed apparent localization of vinculin in the pericentriolar mater ial. Immunoblot analysis confirmed the presence of vinculin in purifie d centrosomal protein preparations. In such protein fractions, anti-vi nculin antibodies reacted with a single polypeptide with an apparent m olecular weight similar to that of vinculin. Stepwise solubilization o f centrosomal structures using urea showed that high urea concentratio ns were required to solubilize centrosomal vinculin, suggesting tight association of vinculin with the pericentriolar material. The identifi cation of vinculin as a component of centrosomes provides a possible m olecular basis for interaction between F-actin and centrosomes. (C) 19 95 Academic Press, Inc.