Synthesis of hyaluronic acid is decreased and synthesis of proteoglycans is increased when cultured mouse epidermal cells differentiate

Newborn mouse epidermal cells proliferate when cultured in 0.05 mm Ca⁺⁺ medium and terminally differentiate when the Ca⁺⁺ is increased to about 1.2 mm, the level found in most cell culture media. We found that hyaluronic acid and proteoglycans were synthesized by isolated cultured newborn mouse epidermal cells and that quantitative and qualitative changes in these macromolecules appeared when proliferating epidermal cultures were induced to differentiate by calcium. A major change that occurred with differentiation was a reduction in synthesis of hyaluronic acid while synthesis of proteoglycans and glycoproteins increased. The proteoglycans synthesized in these cultures were heparan sulfate-proteoglycan (90%) and chondroitin sulfate-proteoglycan (10%), regardless of the calcium level.