Expression of Dentin Sialophosphoprotein in Non-mineralized Tissues

Abstract

SummaryDentin sialophosphoprotein (DSPP) and its cleaved products, dentin phosphoprotein (DPP) and dentin sialoprotein (DSP), play important roles in biomineralization. Believed to be tooth specific, the authors' group revealed its expression in bone, and more recently, they and other groups also showed its expression in a few types of soft tissues. In this study, the authors systematically examined the expression of DSPP in a variety of non-mineralized tissues using reverse-transcription polymerase chain reaction (RT-PCR), real-time PCR, Western immunoblotting, and immunohistochemistry analyses in wildtype mice as well as β-galactosidase assays in the Dspp lacZ knock-in mice. These approaches showed the presence of DSPP in the salivary glands, cartilage, liver, kidney, and brain and its absence in the heart and spleen. Real-time PCR showed that the expression levels of DSPP mRNA in salivary glands, cartilage, liver, and kidney were higher than in the bone. Interestingly, DSPP was observed in the pericytes of blood vessels in the dental pulp, which are believed to be able to differentiate into odontoblasts. On the basis of these observations, the authors conclude that DSPP and/or its cleaved products may fulfill important functions in certain non-mineralized tissues in addition to its role in biomineralization. (J Histochem Cytochem 59:1009-1021, 2011

Proteolytic Processing of Dentin Sialophosphoprotein (DSPP) Is Essential to Dentinogenesis

“…In addition to dentin and bone, DSPP has also been found in certain soft tissues such as the salivary glands, cartilage, liver, kidney, and brain (41,47). It appears that the DSPP-derived products in the non-mineralized tissues may have posttranslational modifications different from those in the dentin.…”

The Rescue of Dentin Matrix Protein 1 (DMP1)-deficient Tooth Defects by the Transgenic Expression of Dentin Sialophosphoprotein (DSPP) Indicates That DSPP Is a Downstream Effector Molecule of DMP1 in Dentinogenesis

“…Detailed descriptions of the primers, protocols, and PCR reaction conditions were provided in our previous reports (20,21,23).…”

Dentin Phosphoprotein Binds Annexin 2 and Is Involved in Calcium Transport in Rat Kidney Ureteric Bud Cells

“…In the DSPP Ϫ/Ϫ knock-out mouse, presumably other calcium channels compensate for the lack of DPP, leading to only a retardation in maturation. Finally, it is worth pointing out that in the adult kidney, DPP is present in the proximal and distal convoluted tubule (20,22), both sites known to be involved in calcium transport (48).…”

“…Having been first isolated from bone or tooth, expression of the SIBLINGs in adults was generally thought to be limited to mineralizing tissues and to playing a role in mineralization. However, recent reports have shown that various members of this family, such as DMP1, osteopontin, and DPP, are present in other tissues where they conceivably modulate additional biological processes including signaling (15)(16)(17)(18)(19)(20)(21)(22). DPP has been implicated to be a coactivator in BMP2 signaling (18) and has also been shown to modulate cell differentiation through integrin signaling and activation of p38, ERK1/2, and JNK, three components of the MAPK pathway (17) and the Smad pathway (23).…”