AN N-TERMINAL PEPTIDE FROM LINK PROTEIN STIMULATES PROTEOGLYCAN BIOSYNTHESIS IN HUMAN ARTICULAR-CARTILAGE IN-VITRO

Objective. To determine the effects of a synthetic N-terminal peptide from link protein on the synthesis of proteoglycans by human articular cartilage. Methods. Explants from adult knee cartilage were maintaine d for 4 days in serum-free Dulbecco's modified Eagle's medium, Peptide s were added for the final 2 days of culture, Synthesis of proteoglyca ns and proteins was measured by the incorporation of S-35-sulfate and H-3-serine, The sizes, sulfation patterns, and serine: sulfate ratios of newly synthesized glycosaminoglycans were measured by gel chromatog raphy, high performance liquid chromatography, and ion-exchange chroma tography. Results. The N-terminal peptide stimulated proteoglycan synt hesis in cartilage from a wide age range of patients of both sexes, Th e newly synthesized glycosaminoglycans were identical in size and comp osition to those of control tissues, and their serine:sulfate ratios r emained unchanged. Conclusion. This N-terminal peptide, which can be l iberated from proteoglycan aggregates by proteolysis, potently stimula ted the synthesis of proteoglycans with normal glycosaminoglycan chain s, The results suggest that the N-terminal peptide may have a regulato ry role in maintaining the integrity of human cartilage matrix.