Proteoglycans Synthesized by Adult Human Epidermis in Whole Skin Organ Culture

Adult human epidermis was cultured in whole skin organ culture under serum-free conditions in the presence of 35SO4. Proteoglycans (PG) comprised about 25% of the total (35SO4)-labeled material produced by epidermis. The rest of the incorporated activity displayed solubility characteristics typical of lipids. The molecular mass and the composition of the 35SO4-labeled epidermal PG and glycosaminoglycans (GAG) were studied using gel filtrations and agarose gel electrophoresis- The 35SO4-label of the epidermal PG was located in heparan sulfate (HS, approximately 75%) and chondroitin/dermatan sulfate (CS/DS, 25%), but not in keratan sulfate as determined by nitrous acid, chondroitinase AC II, chondroitinase ABC, and keratanase digestions, respectively. The molecular mass of the GAG chains was 1040kDa. The 35SO4-1abeled PG were distributed between 60 and 600kDa in agarose gel electrophoresis, with the highest activity at 350kDa. Smaller activity peaks occurred at 150and 60kDa. Digestion of the PG with heparitinase removed most of the activity at 350and 150kDa, whereas chondroitinase ABC removed that at 60kDa. A small amount of activity migrating between 600 and 1000kDa was not affected by any of the GAG-degrading enzymes. Pulse chase experiments showed that the epidermal PG had an average half life of 24h. The results thus demonstrate that human epidermis produces at least three different, rapidly metabolized PG. The PGs from 150 to 350kDa contained heparan sulfate chains, whereas those at 60kDa were chondroitin/dermatan sulfate PG.