The induction of c-fos mRNA expression by mechanical stress in human periodontal ligament cells.

The periodontal ligament is subjected to mechanical loading during occlusion and mastication. Although internuclear transcription factors are associated with the regulatory pathway that converts these extracellular mechanical stimuli into a cellular response, there are no reports on these in human periodontal ligament fibroblasts. In this study, the amounts of c-fos mRNA in human periodontal ligament fibroblasts were investigated shortly after subjecting them to a cyclic tension force in vitro. The mRNA of alkaline phosphatase and the matrix proteins type I collagen, type III collagen, matrix Gla-protein, osteonectin, osteopontin, and osteocalcin were also examined. A significant, rapid, transient increase in c-fos mRNA was detected, which peaked 30 min after the application of mechanical force. However, there was no significant change in the mRNA for alkaline phosphatase or the matrix proteins. These results provide evidence that periodontal ligament fibroblasts and c-fos may play a critical part in the response of periodontal tissue to mechanical stimulation.