A biochemical analysis of human periodontal tissue proteoglycans

Proteoglycans synthesized by periodontal (gingival, periodontal ligament, dental follicle) fibroblasts were analysed by SDS/polyacrylamide and agarose gel electrophoresis after being labelled with radioactive sulphate. Medium, cell membrane and extracellular matrix fractions were analysed separately. Samples were treated with chondroitinase AC, chondroitinase ABC, heparitinase or a combination of chondroitinase ABC and heparitinase before electrophoretic separation of proteoglycans. Antibodies to versican and decorin were used to identify these molecules by Western immunoblots. For steady-state metabolic radiolabelling of fibroblasts, medium and cell membrane fractions contained about equal proportions of radiolabelled proteoglycans (about 43%), whereas less radioactivity (about 14%) was found in proteoglycans of the matrix fraction. Periodontal fibroblasts produce six major proteoglycans: versican, a high-molecular-mass chondroitin sulphate proteoglycan (CSPG); decorin, a dermatan sulphate proteoglycan (DSPG); a membrane-associated heparan sulphate proteoglycan (HSPG); two medium- or matrix-associated HSPGs; and a 91 kDa membrane-associated CSPG. Variation in decorin molecular size was observed in mass cultures of fibroblasts. Similar polydispersity in molecular size of decorin was seen in several clones established from one mass culture.