Keratan sulfate inhibits its release in rabbit chondrocyte

Keratan sulfate (KS) is one of the major glycosaminoglycans in cartilage matrix proteoglycan. We find that exogenously added KS totally blocks keratanase sensitive glycosaminoglycan release measured by radiolabeled ligand. We also find that KS release is potentially inhibited by its own presence as measured by ELISA. When KS is digested with keratanase before its addition to the medium, its inhibitory effect on KS secretion is partially blocked. Exogenously added KS promotes the accumulation of the KS epitope in the cell layer. These data suggest that KS negatively regulates its own secretion.