The proteolytic potential of cellular fibronectin fragments issued from a basement membrane hydrolysate was investigated. Three different gelatinase activities (47, 43 and 37 kDa), located by gelatin zymography, were isolated using successively heparin-agarose, gelatin-agarose and immunopurification with polyclonal antibodies directed against bovine plasma fibronectin. These fragments were also characterized using a monoclonal antibody directed against the extra-domain EDA of cellular fibronectin as a probe. A collagenase activity, reliably indicated by the gelatin zymography pattern, was also found using MCA-Pro-Leu-Gly-Leu-DPA-Ala-Arg-NH2, the intramolecularly quenched fluorogenic substrate of collagenases. From these results, cellular fibronectin was found to be able to exhibit a proteolytic function after limited proteolysis. This MMP-like function could be associated with tissue remodeling in both normal and pathological states, such as metastasis, angiogenesis and tissue repair.
