Dentin sialoprotein (DSP) and dentin phosphoprotein (DPP) play distinct
roles during dentinogenesis. Both dentin extracellular matrix proteins are cleaved
products of dentin sialophosphoprotein (DSPP), an important odontoblastic
differentiation marker. Mutations of the DSPP gene in human and mouse cause
mineralization defects in teeth. During odontogenesis, DSPP is predominantly
expressed in developing teeth whereas its expression is much lower in other tissues.
Therefore, DSPP serves as a unique model to study the mechanisms of spatial-temporal
and tissue-specific gene regulation associated with dentinogenesis. Both in vitro and in
vivo promoter analysis studies have shown that DSPP transcription is controlled by a
series of growth factors and transcriptional factors as well as local factors. Some factors
up-regulate DSPP expression whereas others down-regulate its transcription. Spatialtemporal
DSPP expression at different stages of tooth developmental is mediated by a
complex network of growth factors and transcription factors. Beyond the role of
biomineralization, recent studies have demonstrated that both DSP and DPP may
function as intracellular transductors. DPP is able to induce tooth- and bone-related
gene expressions via the MAPK and Smad signaling pathways while DSP binds to cell
membrane proteins, resulting in activation of intracellular protein kinases. This data
may provide novel insights into the roles of DSP and DPP in cell proliferation and
differentiation besides biomineralization.
Keywords: DSP, DPP, mineralization defects, dentinogenesis, transcription
factors, MAPK, Smad signaling, intracellular protein kinases, cell differentiation.
