EXPRESSION OF PROTEOGLYCANS BY CULTURED CHICK STERNAL CHONDROCYTES

Chondrocytes isolated from the caudal and cephalic ends of the sterna of embryonic chicks were cultured in collagen gels. Differences were f ound, histochemically, between the proteoglycans produced by the ''cau dal'' and ''cephalic'' cultures and with length of Lime in culture. Th e cultures were labelled with [C-14]galactose and [S-35]sulphate at 7 and 21 days in culture and labelled compounds from media, and cell and matrix extracts analysed with Sepharose CL-2B. A large aggrecan-like proteoglycan was detected in the media with some aggregated proteoglyc ans found in the cell extracts even under the dissociating conditions used. One group of C-14-labelled compounds, found in the cell and matr ix extracts, was equivalent in size to chick aggrecan core protein. Sm aller proteoglycans and glycoprotein glycans were present. The types a nd proportions of these proteoglycans varied between the two cell type s demonstrating biosynthetic commitment. (C) 1998 Academic Press.