Structure and regulation of proteoglycan expression in articular cartilage.

Beyond aggrecan, the major proteoglycan present in articular cartilage that confers resistance to compressive load and viscoelasticity to the tissue, other proteoglycan families have been described in cartilage. Among them, d ecorin, biglycan and fibromodulin which belong to the small leucine-rich pr oteoglycans family bind to matrix components, specialty to collagen fibrils and thus regulate fibrillogenesis in cartilage and matrix integrity. These small proteoglycans can also interact with TGF-beta and modulate its bioav ailability and stability The third family is composed by cell surface prote oglycans as syndecans, glypican-1 and betaglycan. These molecules interact with Various components of cell environment (growth factors, proteases, mat rix components, etc) and mediate numerous cell functions. Some modification s of one of these proteoglycan expression occur during degenerative patholo gies and may lead to alteration of the functional properties of the tissue as well as variations in growth factor bioavailability. These factors are i nvolved in the attempt of cartilage repair initiated by chondrocytes in the early stages of osteoarthritis. (C) 2001 Editions scientifiques et medical es Elsevier SAS.