TGF- ß 2對人類牙髓細胞的影響及其訊息傳導機制

Abstract

TGF-ss (Transforming Growth Factor-ss) may regulate the growth, differentiation and function of human dental pulp cells. Our prior study has found that TGF-s inhibited pulp cells growth and stimulated collagen synthesis. Objectives: In this study, we tested the differential effects of TGF-s2 signaling on differentiation of cultured human dental pulp cells. Methods: We used western blotting, immunofluorescent observation, RT-PCR, MTT assay, alkaline phosphatase (ALP) staining, alkaline phosphatase quantitative assay to test our findings. Result: We found that human dental pulp cells expressed mainly TGF-s1, less TGF-s2 and trace amount of TGF-s3 mRNA. Exposure of pulp cells to TGF-s2 (10 ng/ml) induced the phosphorylation of smad2/3, smad1/5/8 and ERK signaling pathways as analyzed by western blotting; TGF-s2 also stimulated the nuclear translocation of smad3 and smad1 as observed by immunofluorescent microscope. Pulp cells expressed strong ALK-P activities in confluent culture for 5 days. Exposure to TGF-s2 (≧ 5 ng/ml) decreased the ALP activity ( P < 0.05 ) and mRNA expression. Pretreatment of pulp cells with SB431542 (an inhibitor of TGF-s ALK-4, ALK-5 and ALK-7 receptors) and to a lesser extent the U0126 (MEK1 inhibitor) prevented the inhibitory effect of TGF-s2 (5 ng/ml) on viable cell number, ALP staining, as well as the ALP mRNA expression in dental pulp cells. Conclusion: These results suggest that TGF-s2 may affect the biological activities of dental pulp cells via autocrine and paracrine fashion by activation the differential signal transduction pathways. These events can be crucial in pulpal repair and regeneration.