Effect of retinoic acid on osteopontin expression in rat clonal dental pulp cells

We studied the effect of retinoic acid on osteopontin synthesis and the mRN A expression in rat clonal dental pulp cells, RPC-C2A, An immunoprecipitati on assay clarified that retinoic acid caused an increase in phosphorylated osteopontin synthesis that was dose-dependent, and marked increases were ob served at retinoic acid concentrations of 10(-6) to 10(-5) M (1.7-fold). A Northern blotting analysis revealed a similar pattern of increase in osteop ontin mRNA expression of up to 6.2-fold of control levels. Because osteopon tin has an important role in the mineralization process, these results sugg est that retinoic acid regulates mineralization, which takes place in the p ulp cavity, including reparative dentin formation.