Genetic evidence for key roles of decorin and biglycan in dentin mineralization.

Targeted disruption of the dentin sialophosphoprotein (DSPP) gene in the mice (Dspp(-/-)) results in dentin mineralization defects with enlarged predentin phenotype similar to human dentinogenesis imperfecta type III. Using DSPP/biglycan (Dspp(-/-)Bgn(-/0)) and DSPP/decorin (Dspp(-/-)Dcn(-/-)) double knockout mice, here we determined that the enlarged predentin layer in Dspp(-/-) teeth is rescued in the absence of decorin, but not in the absence of biglycan. However, Fourier transform infrared (FTIR) spectroscopy analysis reveals similar hypomineralization of dentin in both Dspp(-/-)Bgn(-/0) and Dspp(-/-)Dcn(-/-) teeth.

Dentin sialoprotein and dentin phosphoprotein have distinct roles in dentin mineralization.

Dentin sialophosphoprotein (DSPP), a major non-collagenous matrix protein of odontoblasts, is proteolytically cleaved into dentin sialoprotein (DSP) and dentin phosphoprotein (DPP). Our previous studies revealed that DSPP null mice display a phenotype similar to human autosomal dominant dentinogenesis imperfecta, in which teeth have widened predentin and irregular dentin mineralization resulting in sporadic unmineralized areas in dentin and frequent pulp exposure. Earlier in vitro studies suggested that DPP, but not DSP, plays a significant role in initiation and maturation of dentin mineralization.