Fibronectin fragments bind to and penetrate cartilage tissue resulting in proteinase expression and cartilage damage

A fibronectin fragment induces type II collagen degradation by collagenase through an interleukin-1?mediated pathway

“…Contents of the FN fragments may reach 100 nM in OA cartilage (38), comparable with the concentration used in the present study, which can induce cleavage of CII. In addition, FN fragments can penetrate into cartilage tissue in vitro (52), indicating that products of FN degradation in SF in diseased joints may penetrate articular cartilage. Thus, the induction of MMPs and collagenase-mediated cleavage, as well as that of aggrecan, by FN fragments may play an important role in the pathogenesis of cartilage erosion in diseases such as OA and RA.…”

Potential regulation of cartilage metabolism in osteoarthritis by fibronectin fragments

“…Figure 1 shows the location of these Fn-fs within the Fn subunit. Subsequently, we found that the Fn-fs penetrate cartilage and surround chondrocytes (57) to cause the release of half of the total PG within a few days when cartilage is cultured in the presence of 100 nM or 1 µM Fnfs (56). These concentrations of Fn-fs are at or below measured concentrations in OA synovial fluid (31), consistent with their potential physiologic role.…”

Focal Adhesion Kinase and Mitogen-activated Protein Kinases Are Involved in Chondrocyte Activation by the 29-kDa Amino-terminal Fibronectin Fragment

“…A binding study using radiolabeled FN-f demonstrated a relatively high number of binding sites on chondrocytes (28). Some reports suggest that FN-f binds to chondrocytes through the fibronectin ␣ 5 ␤ 1 integrin receptor since synthetic peptides which contain Arg-Gly-Asp (RGD) integrin-binding sequence block activities of FN-f and anti-␤ 1 integrin antibody blocked binding of the 70-kDa amino-terminal fibronectin fragment, which does not contain an integrin-binding domain, to fibroblasts (29).…”