Abstract
Focal adhesions mediate cell-extracellular matrix adhesion. They are inserted in detergent-resistant membrane microdomains enriched in phosphatidylinositol-4,5-bisphosphate. In spite of the relevance that membrane lipids appear to have on cell adhesion structures, to our knowledge, there are no previous reports on the membrane lipid composition where focal adhesions are located in vivo or on how changes in local membrane composition contribute to focal adhesion maintenance. This may be due to the fact that the explosion of information in the fields of genomics and proteomics has not been matched by a corresponding advancement of knowledge in the field of lipids. The physiological importance of lipids is illustrated by the numerous diseases to which lipid abnormalities contribute. To gain insight into the role of membrane lipid composition in the preservation of epithelial cell adhesion to the substratum, how specific changes in the membrane lipid composition in vivo affect the maintenance of focal adhesions in renal papillae collecting duct cells has been previously studied. It is currently considered that phosphatidylinositol-4,5-bisphosphate plays a crucial role in the maintenance of assembled focal adhesion. However, such pool of polyphosphoinositides has to be part of a domain of a specific lipid composition to serve as a membrane lipid stabilizing the focal adhesion plaque.