Cartilage chondrolysis by fibronectin fragments is associated with release of several proteinases: stromelysin plays a major role in chondrolysis.
We have reported that three different Fn fragments (Fn-f) added to bovine articular cartilage cultured in serum-free DMEM cause marked elevation of proteoglycan (PG) degradation and release into the culture media. We report here that the PG release required the continual presence of Fn-f, that PG release still occurred when serum-free cultures were switched to bovine synovial fluid media, and that addition of recombinant IGF-1, TGF-beta, and recombinant interferon gamma to cultures did not affect Fn-f-mediated PG release. The Fn-f caused a 25-fold enhanced release of stromelysin-1 protein from cartilage by Day 1 and up to 120-fold by Day 3. The stromelysin form released was 43 kDa, the activated form of pro-stromelysin-1. This stromelysin form apparently played a major role in Fn-f-mediated PG release, since addition of Sepharose-bound anti-stromelysin-1 to cartilage cultures greatly slowed rates of PG release. Potential activators of pro-stromelysin-1, plasmin, and u-PA (urinary plasminogen activator), were also detected in conditioned media of Fn-f-treated cartilage. u-PA levels were increased in the presence of the Fn-f but by only a few fold. Addition of alpha-1-antiproteinase inhibitor, which can block enzymatic activity of u-PA, was found to inhibit about half the PG-releasing activity of the Fn-f. Levels of TIMP-1, the 30-kDa tissue inhibitor of metalloproteinases, which can inhibit stromelysin, doubled within 24 h when a Fn-f was added to culture. These data suggest that stromelysin-1 may be a major mediator of Fn-f-mediated PG release from cartilage.
Xie
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DL
Department of Biochemistry, Rush Medical College at Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612-3864.
Hui
F
F
Meyers
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R
Homandberg
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GA
D000818:Animals; D015153:Blotting, Western; D002358:Cartilage, Articular / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D003545:Cysteine / Q000378:metabolism; D004789:Enzyme Activation; D005353:Fibronectins / Q000494:pharmacology*; D018093:Gelatinases / Q000378:metabolism; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D007700:Kinetics; D019278:Matrix Metalloproteinase 3; D008666:Metalloendopeptidases / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D011509:Proteoglycans / Q000032:analysis / Q000096:biosynthesis*; D011994:Recombinant Proteins / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000378:metabolism*; D013462:Sulfur Radioisotopes; D013582:Synovial Fluid / Q000502:physiology*; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D005353:Fibronectins; D010446:Peptide Fragments; D011509:Proteoglycans; D011994:Recombinant Proteins; D013462:Sulfur Radioisotopes; D016212:Transforming Growth Factor beta; D007334:Insulin-Like Growth Factor I; D007371:Interferon-gamma; D008715:Methionine; D012697:Serine Endopeptidases; D018093:Gelatinases; D008666:Metalloendopeptidases; D019278:Matrix Metalloproteinase 3; D003545:Cysteine