Sulfated glycosaminoglycan synthesis and its regulation by transforming growth factor-beta in rat clonal dental pulp cells

Dental pulps contain sulfated glycosaminoglycans (GAGs), such as chondroiti n 4-sulfate (CSA/4CS), dermatan sulfate (CSB/DS), and chondroitin 6-sulfate (CSC/6CS). Sulfated GAGs play important roles in mineralization and collag en fibrillogenesis during primary, secondary, and reparative dentin formati ons. Transforming growth factor-beta (TGF-beta) is a potent regulator for s everal extracellular matrix (ECM) components and modulates the proliferatio n and differentiation. Using rat clonal dental pulp cells (RPC-C2A), we inv estigated the constituents of GAGs synthesized by the cells and the effect of TGF-beta on their synthesis by measuring the radioactivity of [S-35]sulf ate incorporated into GAG fractions. Cellulose acetate electrophoresis anal ysis revealed that RPC-C2A cells synthesized CSA and CSB but not CSC and th at 10 ng/ml of TGF-beta increased the production of CSA and CSB in the cell /ECM fraction. Measurement of [S-35]sulfate incorporation showed a signific ant increase in the amount of GAGs by TGF-beta, 1.3-fold CSA, and 1.2-fold CSB in the cell/ECM fraction. In the medium fraction the most secreted GAG was CSA, whereas CSB was stored in the cell/ECM fraction. Secreted CSA in t he medium was markedly increased by 10 ng/ml of TGF-beta (1.7-fold). These findings indicate that CSA and CSB are major sulfated GAGs synthesized by R PC-C2A cells and that TGF-beta acts as a stimulator of sulfated GAG synthes is in dental pulp cells.