Retinoic acid alters the proportion of high mannose to complex type oligosaccharides on fibronectin secreted by cultured chondrocytes.

Fibronectin synthesized by retinoic acid-treated chondrocytes exhibits a higher apparent subunit molecular weight in sodium dodecyl sulfate-polyacrylamide gels than fibronectin from untreated cultures. Analyses of peptide fragments show that retinoic acid treatment alters the apparent molecular weight of the collagen-binding fragment. Approximately one-sixth of the carbohydrate moieties on the collagen-binding fragment from control chondrocytes were sensitive to endo-beta-N-acetylglucosaminidase H, whereas the collagen-binding fragment from treated chondrocytes was more resistant to endo-beta-N-acetylglucosaminidase H. These findings indicate that chondrocyte fibronectin contains oligosaccharides of the high mannose or hybrid type in contrast to fibroblast fibronectin which only contains complex type carbohydrate chains and that retinoic acid treatment results in a higher proportion of complex type carbohydrate chains on chondrocyte fibronectin.