Two distinct mechanisms of fibroblast adhesion.

The adhesion of cells to the connective tissue matrix is commonly thought to be governed by fibronectin, a pericellular glycoprotein with binding sites for cell surfaces, collagen and glycosaminoglycans. Here we report evidence that Chinese hamster ovary (CHO) cells possess an alternative mechanism for adhesion which is independent of fibronectin. Cells of a variant CHO clone called ADvF11 are defective in their ability to adhere to fibronectin-coated substrata, but can adhere to a substratum coated with SAM (substrate-attached material), a pericellular material produced by fibroblasts. The adhesion of wild-type CHO cells to fibronectin-coated substrate and adhesion of ADvF11 cells to SAM-coated substrata are differentially sensitive to proteolytic treatment. This suggests that there are two distinct adhesion mechanisms for CHO cells, only one of which is dependent on fibronectin.