p38 Mitogen-activated protein kinase and alkaline phosphatase in human dental pulp cells

ObjectiveThe objective of this study was to investigate the implication of p38 mitogen-activated protein kinase (MAPK) in mediating alkaline phosphatase (ALPase) activity in human dental pulp cells (HPCs).Study designNuclear translocation of p38 was observed by immunofluorescence in isolated HPCs treated with transforming growth factor β1 (TGF-β1). TGF-β1 was used to examine the interaction between p38 MAPK and Smad pathway. Role of p38 kinase in mediating ALPase activity was determined with SB203580, a specific inhibitor for the p38 pathway. Lipopolysaccharide (LPS) or TGF-β1 was added to inhibit or increase ALPase activity. Statistical analysis was performed by unpaired t test.ResultsTGF-β1 induced nuclear translocalization of p38. Blockage of p38 pathway with SB203580 inhibited translocation of Smad2/3 to nuclei. ALPase activity decreased in cells treated with SB203580, in contrast to its vehicle (P < .05). Inhibition on enzyme activity by LPS was exacerbated by SB203580 (P < .05). Treatment with SB203580 before addition of TGF-β1 also made a significant decrease in ALPase activity (P < .05).ConclusionsThese results suggest that p38 MAPK is implicated in regulating ALPase activity in HPCs and may interact with Smad pathway.