Membrane Lipid Composition Plays a Central Role in the Maintenance of Epithelial Cell Adhesion to the Extracellular Matrix

Focal contacts (FC) are membrane-associated multi-protein complexes that mediate cell-extracellular matrix (ECM) adhesion. FC complexes are inserted in detergent-resistant membrane microdomains enriched in phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2); however, the influence of membrane lipid composition in the preservation of FC structures has not been extensively addressed. In the present work, we studied the contribution of membrane lipids to the preservation of renal epithelial cell adhesion structures. We biochemically characterized the lipid composition of membrane-containing FC complexes. By using cholesterol and PtdIns(4,5)P2 affecting agents, we demonstrated that such agents did not affect any particular type of lipid but induced the formation of new FC-containing domains of completely different lipid composition. By using both biochemical approaches and fluorescence microscopy we demonstrated that phospholipid composition plays an essential role in the in vivo maintenance of FC structures involved in cell-ECM adhesion.