Role of Cdk5 in Dental Pain

Objectives: Dentin-pulp layer is implicated in dental pain although the molecular mechanism is not totally understood. Previously, we reported that Cdk5, an important kinase involved in inflammatory orofacial pain, is activated by inflammation in odontoblast-like MDPC-23 cells and in trigeminal nociceptive neurons, suggesting a role for Cdk5 in dental pain. Here we evaluated the expression and regulation of Cdk5 activity by TNF-α or LPS, two inflammatory mediators involved in dental pain, in differentiated mouse dental cells.
Methods:
Odontoblast activity of differentiated dental pulp cells was evaluated by Alizarin Red and expression and localization of odontoblast markers (DSPP and DMP-1). By Western blot and immunofluorescence we evaluated the expression of Cdk5/p35 and its regulation by TNF-α or LPS in dental pulp cells and in human teeth slices.
Results: We found that differentiated dental pulp cells have increased odontoblast activity and Cdk5/p35 expression and activity. TNF-α or LPS treatment also increased Cdk5/p35 expression and Cdk5 activity in dental pulp cells. Interestingly, we showed for first time expression of Cdk5/p35 and Cdk5-mediated-TRPV1 phosphorylation in odontoblast layer of human teeth section.

Conclusions:
Together our results demonstrate that dental cells express Cdk5/p35, and inflammatory mediators increased Cdk5 activity, suggesting that Cdk5 might be implicated in dental pain.