The Roles of Dentin Matrix Protein 1 in Osteogenesis

Dentin matrix protein 1(DMP1) is an acidic phosphoprotein of the SIBLING family of noncollagenous proteins(NCPs).DMP1 is abundant in dentin,and is also distributed in bones as an essential control factor for osteogenesis.Fragmented DMP1 exists within the extracellular matrix of bone,including a 57 kD N-terminal,a 37 kD C-terminal fragment and DMP1-PG.The localization of these DMP1 forms are found in different the bone compartments and cell types suggesting their different roles in osteogenesis.DMP1 contains multiple acidic domains riched in Ser,Glu,and Asp,and many of the Ser reside in the consensus motif of hypothetical phosphorylation sites of casein kinases I and II.The acidic property of DMP1 may allow a high calcium ion-binding capacity that is necessary for mineralization.The proteolytic processing of DMP1,which releases N-DMP1 and C-DMP1,may be important for the formation and mineralization of bones.Experiments indicate a dual biological function for DMP1 both as a transcriptional signal during early differentiation of osteoblasts and as an initiator of mineralization during the terminal differentiation of osteoblasts.Human DMP1 mutations are linked to the condition known as autosomal recessive hypophosphatemic rickets.This review summarizes the late progress in understanding the role of DMP1 in osteogenesis.