Fibronectin-independent adhesion of fibroblasts to the extracellular matrix: mediation by a high molecular weight membrane glycoprotein.

Abstract

Fibroblstic CHO [chinese hamster ovary] cells readily adhere to fibronectin (Fn) coated substrata. From the parental (WT) cell population selected a series of adhesion variants (ADv F11 cells) that cannot adhere to Fn substrata (Harper and Juliano 1980.). ADv cells readily adhere to substrata coated with extracellular matrix material (ECM) derived from human diploid fibroblasts by a mechanism that does not involve fibronectin (Harper and Juliano 1981). The Fn-dependent adhesion mechanisms of parental cells (type I adhesion) and the ECM-dependent adhesion of ADv cells (type II adhesion) can also be discriminated on the basis of their differential sensitivity to proteolysis, with the type II mechanism being far more sensitive. Parental CHO cell possess both type I and type II mechanisms, whereas ADv cells possess only the type II mechanism. A high MW membrane glycoprotein (gp 265) that seems to play a role in type II adhesion is identified. This component is detected by [125I]lactoperoxidase or [3H]borohydride-galactose oxidase labeling of surface proteins in WT and ADv cells. Cleavage of gp 265 with low doses of proteases correlates completely with the loss of type II adhesion capacity. CHO cells possess 2 functionally and biochemically distinct adhesion mechanisms, 1 involving exogenous Fn and the other mediated by the membrane component gp 265.