Identification of genes related to mechanical stress in human periodontal ligament cells using microarray analysis

Background and Objective: Differential expression of genes in human periodontal ligament (PDL) under mechanical stress, such as orthodontic force, is thought to be involved in the remodeling of PDL cells and periodontal tissues. However, little is known about the genes expressed in PDL cells under mechanical stress. Material and Methods: We employed microarray analysis to assess, in a comprehensive manner, the gene expression profiles in PDL cells compressed by a static force using an in vitro three-dimensional culture system. Six genes were selected and validated by quantitative real-time polymerase chain reaction analysis, consistent with the microarray data. Results: The microarray data revealed that 108 of 30,000 genes tested were differentially expressed by mechanical force loading. Among them, 85 genes were up-regulated by mechanical stress, while 23 genes were down-regulated, judging by the thresholds of a two-fold increase/decrease compared with the controls. Thirty-two of the up-regulated and eight of the down-regulated genes, well-characterized in protein function, were involved in numerous biological processes including cell communication, cell signaling, cell cycle, stress response, and calcium release. However, several genes differentially expressed in our microarray data have not been well defined as stress-response molecules. Conclusion: Our microarray is the first to show the gene profile in PDL cells caused by mechanical stress; however, further studies to clarify the physiological function of these molecules in PDL cells are required.