The potential role of transient receptor potential type A 1 as a mechanoreceptor in human periodontal ligament cells

Transient receptor potential type A 1 ( TRPA 1) is reported to be a C a 2+ ‐permeable channel and is activated by cold temperatures and mechanical stimuli in the hair cells and in dorsal root ganglion. Using a DNA microarray, we found that TRPA 1 was significantly up‐regulated in human periodontal ligament (h PDL ) cells 2 d after intermittent mechanical stimulation (i MS ) loading compared with unloaded cells. Although h PDL cells are known to respond to mechanical stimulation induced by occlusal force, little is known about the expression and functional role of TRPA 1 in these cells. Therefore, we investigated the effects of iMS on TRPA 1 expression and its signaling pathway in h PDL cells. Intermittent mechanical stimulation loading up‐regulated TRPA 1 expression in hPDL cells in a time‐dependent manner, but had no effect on other mechanoreceptors. Furthermore, iMS significantly increased the phosphorylation of mitogen‐activated protein kinases ( MAPK s), especially extracellular signal‐regulated kinase 1/2 ( ERK 1/2) and p38, and the expression of C ‐ C chemokine ligand 2 ( CCL 2). Transient receptor potential type A 1 agonists also increased MAPK phosphorylation and the intracellular C a 2+ concentration. By contrast, inhibition or silencing of TRPA 1 partially suppressed i MS ‐induced MAPK phosphorylation. In summary, i MS during occlusion activates TRPA 1 and MAPK signaling in periodontal ligament tissues, suggesting that TRPA 1 regulates the mechanosensitivity of occlusal force via activation of MAPK s in h PDL cells.