DSPP

DSPP, or dentin sialophosphoprotein, is a secreted extracellular matrix protein produced by odontoblasts and a major component of dentin. In humans, the DSPP gene encodes this protein and is located on chromosome 4. The DSPP protein is synthesized as a single precursor that is proteolytically cleaved into two mature products: dentin sialoprotein (DSP) and dentin phosphoprotein (DPP). These two fragments, though processed from a common precursor, participate in dentin formation in complementary ways and remain associated within the dentin matrix.

DSPP belongs to the SIBLING family of noncollagenous extracellular matrix proteins involved in mineralized tissues. The DSP and DPP fragments have distinct biochemical properties; DPP is highly acidic and heavily phosphorylated, which supports calcium binding and interaction with hydroxyapatite, while DSP contributes to matrix organization. The precise processing and function of these fragments are active areas of dental research, with evidence that the DSPP-derived proteins regulate mineral deposition and dentin matrix integrity.

Expression of DSPP is strongest in odontoblasts during dentinogenesis, the process of dentin formation in teeth. Animal studies, including DSPP knockout models, show dentin defects and altered mineralization when DSPP function is disrupted, underscoring its essential role in normal dentin development.

Clinical significance of DSPP mutations is primarily linked to dentinogenesis imperfecta, particularly types II and III, which are inherited in an autosomal dominant pattern. Affected teeth often display opalescent discoloration, reduced dentin with abnormal tubule structure, and increased susceptibility to wear and fracture. Ongoing research aims to elucidate how specific variants alter DSPP processing and dentin mineralization.