Biochemistry of Dentin Matrix Proteins

Sponsored by: Craniofacial Biology

Description: During dentinogenesis, odontoblasts secrete an unmineralized, type I collagen-rich extracellular matrix (ECM), termed predentin. Predentin is transformed to dentin when apatite crystals are deposited. This process of biomineralization is dynamic, involving multiple changes that occur within the window of time that predentin is formed and it is converted to dentin. In addition to type I collagen, the ECM of dentin contains a number of non-collagenous proteins (NCPs). One category of NCPs is the SIBLING family, which includes dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), bone sialoprotein and osteopontin. These polyanionic SIBLING proteins are believed to play key biological roles in the mineralization of dentin, although we do not know their precise involvement in controlling mechanisms of dentin mineralization. Some functions of these phosphorylated glycoproteins in the SIBLING family are dependent on the nature and extent of posttranslational modifications such as proteolytic processing, phosphorylation and glycosylation. Realizing the importance of these modifications, our laboratory has performed studies on ECM proteins extracted from dentin that represent the actual in vivo forms. We strongly feel that a full understanding of dentin matrix proteins depends on testing “native” forms. A clear illustration of this position is the findings that DSPP and DMP1 are present in dentin ECM in the form of proteolytically processed fragments, a fact that could only be ascertained using protein chemistry approach. Thus, the biochemical analysis of dentin matrix proteins remains a powerful means in elucidating the mechanisms of dentin formation.


		12:15 PM	Biochemistry of Dentin Matrix Proteins C. QIN, Baylor College of Dentistry, Dallas, TX, USA

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