RESPONSE OF STRATIFIED CULTURES OF HUMAN KERATINOCYTES TO DISRUPTION OF PROTEOGLYCAN SYNTHESIS BY P-NITROPHENYL-BETA-D-XYLOPYRANOSIDE

Proteoglycans play a role in regulating proliferation and adhesion of cells to each other and to the basal lamina. Synthesis of proteoglycan s is disrupted by beta-xylosides, which serve as alternate substrate s ites for glycosaminoglycan chain attachment and therefore prevent glyc osylation of the core protein. We have investigated the effects of p-n itrophenyl-beta-D-xylopyranoside (PNP-xyloside) on cultured human kera tinocytes. Stratified cultures were incubated for 7 days with PNP-xylo side (0.05-2.0 mM). Concentrations as low as 0.05 mM increased the sec retion of free chondroitin sulfate by 10-15-fold over untreated cultur es. Cell-associated proteoglycan decreased as PNP-xyloside concentrati on increased. At 2 mM PNP-xyloside, heparan sulfate as well as chondro itin sulfate addition to core proteins was disrupted: the core protein of epican, a heparan sulfate form of CD44 found on keratinocytes, was detected immunologically but lacked heparan sulfate. 2.0 mM PNP-xylos ide reduced the number of attached cells by 20-25% after 7 days, but h ad little effect on morphology or protein synthesis. These results ind icate that intact proteoglycans are not critical for maintaining epide rmal keratinocyte stratification, cell-cell adhesion, or growth. (C) 1 994 Wiley-Liss, Inc.