sialophosphoprotein

Sialophosphoprotein, commonly referred to as dentin sialophosphoprotein (DSPP), is a secreted member of the secretory calcium-binding phosphoprotein (SCPP) family. It is synthesized as a single precursor that is proteolytically cleaved to yield two mature dentin matrix proteins: dentin sialoprotein (DSP) and dentin phosphoprotein (DPP). The DSPP gene encodes this precursor and is expressed primarily by odontoblasts during dentin formation, with lower levels detected in bone and other mineralizing tissues.

Functionally, DSPP is involved in dentin mineralization. It is a highly phosphorylated, acidic protein, and DPP is thought to promote hydroxyapatite nucleation and regulate crystal growth, while DSP may modulate mineralization and matrix organization. Proteolytic processing into DSP and DPP appears essential for full activity, and the two mature proteins likely perform complementary roles in the mineralization process within dentin.

Clinical significance is linked to DSPP mutations. Pathogenic variants in DSPP cause dentinogenesis imperfecta types II and III and dentin dysplasia type II, disorders characterized by abnormal dentin structure, opalescent dentin, and increased tooth attrition. Genetic and experimental studies, including analyses in humans and animal models, support a critical role for DSPP in proper dentin formation and mineralization.