CHANGES IN KERATINOCYTE ADHESION DURING TERMINAL DIFFERENTIATION - REDUCTION IN FIBRONECTIN BINDING PRECEDES ALPHA-5-BETA-1-INTEGRIN LOSS FROM THE CELL-SURFACE

During terminal differentiation keratinocytes move out of the basal layer of the epidermis and thereby lose contact with the basement membrane. We show that terminal differentiation in culture involves loss of adhesiveness to fibronectin, laminin, and collagen types I and IV. The adheslve changes precede, by several hours, loss of the α2β1, α3β1, and α5β1 integrins from the cell surface. Keratinocyte adhesion to fibronectin is mediated by the α5β1 integrin, and the decrease in adhesion of intact cells to fibronectin is correlated with a decrease in the ability of α5β1 receptors to bind fibronectin. Thus modulation of integrin function early in terminal differentiation may be an early event determining cell migration out of the basal layer. © 1990.