Interaction of fibronectin with collagen: age-specific defect in the biological activity of human fibroblast fibronectin.

Fibronectins isolated fro early-passage and late-passage (in vitro aged) human fibroblasts were shown to differ in their ability to support cell adhesion and to influence cell morphology. Because fibroblast adhesion requires interactions between fibronectin, the cell surface, and the component of the extracellular matrix, we examined those functions in isolated cellular fibronectin. In comparison to fibronectin isolated from early-passage cells, fibronectin from late-passage cells bound poorly to native collagen types I and II. No differences were observed in the binding of the two fibronectins to denatured collagen. The binding of both fibronectins to native collagen was similarly promoted by heparin. Cell binding activity was evaluated by using a Boyden chamber assay to measure chemotaxis in response to either fibronectin. No differences were detected in cell binding. Comparisons of molecular weights by NaDodSO4/polyacrylamide gel electrophoresis reveals that fibronectin from late-passage cells is larger than that from early-passage cells. That difference is observed both in fibronectins isolated from conditioned media and in fibronectins isolated from the cell layer. These data support the hypothesis that late-passage cells produce a structurally and functionally distinct fibronectin. The defective binding to native collagen may account for some aspects of the aged phenotype.