Comparative analysis of proteoglycans synthesized by chick corneal stromalcells in cell culture and organ culture

Proteoglycans (PGs) synthesized by chick corneal stromal cells in cell cult ure and organ culture were metabolically radiolabelled with [S-35]sulfate ( for glycosaminoglycans) and [H-3]leucine (for core proteins). Media, cell e xtracts and organ extracts from cultures were chromatographed on DEAE-Sepha cel columns and separated into three fractions: the pass-through fraction ( Fraction 1: nonsulfated PGs, hardly sulfated PGs, or glycoproteins with som e oligosaccharides), the fraction eluted with a low salt concentration (Fra ction 2: undersulfated PGs), and the fraction eluted with a high salt conce ntration (Fraction 3: highly sulfated PGs). The PG compositions of each fra ction of cell culture and organ culture were then compared. While the propo rtions of highly sulfated KSPG in Fractions 3 of medium and cell extract of cell culture were both very low compared with those of medium and organ ex tract of organ culture, respectively, the proportions of highly sulfated CS /DS PG in Fractions 3 of those of cell culture were higher than those of or gan culture. On the other hand, the proportions in the S-35 activities of n onsulfated or undersulfated KSPG in Fractions 1 and 2 of medium and cell ex tract of cell culture were comparable to those of organ culture. Furthermor e, the proportions of core proteins of undersulfated KSPG in Fractions 2 we re higher in cell culture than in organ culture. These results show that, w hen the cells are cell-cultured, the degree of sulfation of KS chains decre ases markedly, but the syntheses of the glycosaminoglycan backbone and core protein are maintained.