ABSTRACT
PURPOSE: To investigate the effects of mutated cartilage oligomeric matrix protein (COMP) on the synthesis of cartilage-specific major matrix proteins of Swarm rat chondrosarcoma chondrocytes. MATERIALS AND METHODS: The Swarm rat chondrosarcoma chondrocytes transfected with chimeric construct consisting of a mutant gene of human COMP and an amino acid FLAG tag sequence were cultured in agarose gel. Formation of extracellular proteoglycan and type-II collagen of the cells were evaluated by immunohistochemical staining and measuring 35S-sulfate incorporation. RESULTS: No difference was observed in type-II collagen detection among the cell line expressing mutant COMP and control cell lines. Histochemical staining of sulfated proteoglycans with safranin-O showed lower amounts of proteoglycans were incorporated into the extracellular matrix of chondrocytes transfected with mutant gene. 35S-sulfate incorporation into the cell/matrix fractions demonstrates marked lower radiolabel incorporation compared to control cells. CONCLUSION: Mutation of COMP impacts the processing of proteoglycans rather than type-II collagen in three-dimensional culture of Swarm rat chondrosarcoma chondrocytes.