Gene Expression Patterns of Murine Dentin Matrix Protein 1 (Dmp1) and Dentin Sialophosphoprotein (DSPP) Suggest Distinct Developmental Functions In Vivo

• Published in: Journal of bone and mineral research Vol. 12; no. 12; pp. 2040 - 2049
• Main Authors: D'souza, R. N., Cavender, A., Sunavala, G., Alvarez, J., Ohshima, T., Kulkarni, A. B., MacDougall, M.
• Format: Journal Article
• Language: English
• Published: Washington, DC John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR) 01-12-1997; American Society for Bone and Mineral Research
• Subjects: Animals; Biological and medical sciences; Extracellular Matrix Proteins; Fundamental and applied biological sciences. Psychology; Gene Expression - genetics; Gene Expression - physiology; Gene Expression Regulation, Developmental - genetics; Gene Expression Regulation, Developmental - physiology; In Situ Hybridization; Mice; Minerals - metabolism; Mouth. Exocrine and endocrine salivary glands. Teeth. Esophagus; Odontogenesis - genetics; Odontogenesis - physiology; Osteogenesis - genetics; Osteogenesis - physiology; Phosphoproteins - genetics; Polymerase Chain Reaction; Pulmonary Alveoli - chemistry; Pulmonary Alveoli - embryology; Pulmonary Alveoli - metabolism; RNA - analysis; RNA - genetics; RNA Probes; Time Factors; Vertebrates: digestive system; Dentin; Rodentia; Gene expression; Vertebrata; Mammalia; Sialoproteins; Mouse; Phosphoproteins; Dentinogenesis; Secretory protein; Development; Extracellular matrix; Tooth
• ISSN: 0884-0431; 1523-4681
• DOI: 10.1359/jbmr.1997.12.12.2040

Although the precise mechanisms of the conversion of predentin to dentin are not well understood, several lines of evidence implicate the noncollagenous proteins (NCPs) as important regulators of dentin biomineralization. Here we compared the in vivo temporospatial expression patterns of two dentin NCP genes, dentin matrix protein 1 (Dmp1), and dentin sialophosphoprotein (DSPP) in developing molars. Reverse transcription‐polymerase chain reaction was performed on embryonic day 13 to 1‐day‐old first molars using Dmp1‐ and DSPP‐specific primer sets. Dmp1 transcripts appeared at the late bud stage, while DSPP mRNA was seen at the cap stage. Expression of both genes was sustained throughout odontogenesis. In situ hybridization analysis revealed interesting differences in the expression patterns of these genes. While Dmp1 and DSPP showed coexpression in young odontoblasts before the start of mineralization, the expression of these genes was notably distinct at later stages. Dmp1 expression decreased in secretory odontoblasts after the appearance of mineral, while high levels of DSPP were sustained in odontoblasts. In early secretory ameloblasts, DSPP expression was transient and down‐regulated with the appearance of dentin matrix. Interestingly, Dmp1 expression became evident in ameloblasts during the maturative phase of amelogenesis. In contrast to Dspp expression that was tooth‐specific, Dmp1 was expressed by osteoblasts throughout ossification in the skeleton. Probes directed to the “DSP” and “DPP” regions of the DSPP gene showed identical patterns of mRNA expression. These data show that the developmental expression patterns of Dmp1 and DSPP are distinct, implying that these molecules serve different biological functions in vivo.