Critical Role of Trps1 in Mineralization of 17IIA11 Predontoblastic Cells

Objective: Mutations in the TRPS1 gene cause tricho-rhino-phalangeal syndrome (TRPS) and Ambras syndrome that manifest with skeletal, dental and hair abnormalities. The TRPS1 gene codes for the transcription factor that has been shown to regulate endochondral bone development. Recently, growing evidence suggests TRPS1 involvement in the mineralization process. During endochondral bone formation Trps1 is expressed in perichondrial cells prior to their mineralization. An analogous expression pattern is observed in developing teeth, where Trps1 is highly expressed in preodontoblasts. Based on the Trps1 expression pattern and clinical presentation of TRPS we hypothesize that TRPS1 plays important role in the development of cells that are destined to produce mineralizing matrix. In these studies we address the role of Trps1 in the differentiation of odontoblasts.

Method: The 17IIA11 preodontoblastic cell line, which expresses odontoblast markers and is capable of producing mineralizing matrix (when cultured in differentiation conditions) was used to generate a Trps1-deficient line by shRNA-mediated knockdown. Effects of Trps1 deficiency on mineralization were evaluated by alkaline phosphatase and alizarin red staining. Changes in gene expression pattern were analyzed by an Affimetrix Mouse Exon 1.0 ST Array and confirmed by qRT-PCR. In addition, expression of selected genes was analyzed in teeth of Trps1 mutant mice by IHC.

Result: Trps1 deficiency in the 17IIA11 preodontoblastic cell line results in loss of their mineralization potential. Several genes required for dentin formation and the mineralization process were significantly downregulated in Trps1 deficient cells.

Conclusion: Our studies demonstrate that Trps1 is required for expression of genes critical for mineralization and may be important for odontoblast terminal differentiation.