Notch Signaling in the Dental Pulp

Objectives: Notch signaling is one of the fundamental factors for the development and functions of various cells and tissues through its complex actions. For some cells and tissues, their development and/or functions are regulated positively by Notch signaling, while it is a negative regulator for others. We revealed that activation of Notch signaling, which was induced by transfection of osteoblastic cells with a constitutive active Notch-1 mutant (Notch-IC), down-regulated the differentiation of osteoblasts. Although pulpal mesenchymal cells are possible candidates for the progenitor cells of odontoblasts, precise roles of Notch signaling in odontoblast differentiation are still unknown. The purpose of this study was to examine the expression profile of Notch in the dental pulp.

Methods: RNA was extracted from the rat incisor pulp tissues, primary cultured dental pulp cells, and cloned dental pulp cells: OLC. All cells were cultured in alpha-modified minimal essential medium in the presence of 10% FBS and antibiotics. Real time RT-PCR with specific primers was used to evaluate the expression of Notch related gene expression.

Results: The rat and human dental pulp cells possessed high alkaline phosphatase activity and dentin sialoprotein expression. Expression of Notch1-3, Hes1, Hey1 and other Notch signaling molecules was detected in pulpal cells and pulpal tissues.

Conclusion: Notch signaling may be one of the essential modulators in pulpal cell differentiation and function.