Local regulation of tooth mineralization by sphingomyelin phosphodiesterase 3.

Z Khavandgar, S Alebrahim, H Eimar, F Tamimi, M D McKee, M Murshed

Faculty of Dentistry, McGill University, Montreal, Quebec, Canada.

Journal of dental research 2013 Apr

filter terms:

Sphingomyelin phosphodiesterase 3 (Smpd3) encodes a membrane-bound enzyme that cleaves sphingomyelin to generate several bioactive metabolites. A recessive mutation called fragilitas ossium (fro) in the Smpd3 gene leads to impaired mineralization of bone and tooth extracellular matrix (ECM) in fro/fro mice. In teeth from fro/fro mice at various neonatal ages, radiography and light and electron microscopy showed delayed mantle dentin mineralization and a consequent delay in enamel formation as compared with that in control +/fro mice. These tooth abnormalities progressively improved with time. Immunohistochemistry showed expression of SMPD3 by dentin-forming odontoblasts. SMPD3 deficiency, however, did not affect the differentiation of these cells, as shown by osterix and dentin sialophosphoprotein expression. Using a transgenic mouse rescue model (fro/fro; Col1a1-Smpd3) in which Smpd3 expression is driven by a murine Col1a1 promoter fragment active in osteoblasts and odontoblasts, we demonstrate a complete correction of the tooth mineralization delays. In conclusion, analysis of these data demonstrates that Smpd3 expression in odontoblasts is required for tooth mineralization.

Citation

Z Khavandgar, S Alebrahim, H Eimar, F Tamimi, M D McKee, M Murshed. Local regulation of tooth mineralization by sphingomyelin phosphodiesterase 3. Journal of dental research. 2013 Apr;92(4):358-64