Abstract
Enamel is generated by ameloblast derived from dental epithelium and enamel formation requires reciprocal epithelial-mesenchymal interaction. TGF-β1 is one of the signaling molecules known to regulate the cross talk between dental epithelia and mesenchymal cells. However, TGF-β1 effect on the process of enamel formation is little known. We investigated the role of TGF-β1 on calcified extracellular matrix (ECM) by using primary amaloblast culture system. Dental epithelial cells from the area that contained cells of the ameloblast-lineage were prepared from lower incisors of 8-day-old ICR mice. They were divided into 4 groups and seeded onto the collagen-coated culture dishes (104-105 cells/mL) in HuMedia-KG2 (Kurabo Ind. Ltd.) medium. After the cells were grown to 100% confluency, we added TGF-β1 and CaCl2 to each group, as follows, 1) control, 2) TGF-β1, 3) CaCl2, and 4) TGF-β1 and CaCl2. After experiments for 10-14 days, we examined for the calcification of ECM by alizarin staining and stimultaneously isolated mRNA from each group to investigate for the alkaline phosphatase (ALP) activity. As a result, group 3 (with CaCl2) was the most staining by alizarin. Group 4 (with TGF-β1 and CaCl2) was weaker staining than group 3, whereas group 1 (control) and 2 (with TGF-β1) were not stained. For the activity of ALP, we confirmed stronger expression in group 3 than in group 1 and 4, while ALP expression of group 2 was the most light. These results indicated that TGF-β1 suppressed the ameloblast-formed calcification of ECM. [J Physiol Sci. 2008;58 Suppl:S203]
