The NH₂-terminal and COOH-terminal Fragments of Dentin Matrix Protein 1 (DMP1) Localize Differently in the Compartments of Dentin and Growth Plate of Bone

Izabela Maciejewska ^1*, Cameron Cowan ¹, Kathy Svoboda ¹, William T. Butler ¹, Rena D’Souza ¹ and Chunlin Qin ¹

¹ Department of Biomedical Sciences, Texas A&M Health Science Center, Baylor College of Dentistry, Dallas, Texas

^* To whom correspondence should be addressed. E-mail: imaciejewska{at}bcd.tamhsc.edu.

Submitted on September 3, 2008
Accepted on 1 October 2008

	Abstract

Multiple studies have demonstrated that dentin matrix protein 1 (DMP1) is essential for bone and dentin mineralization. After posttranslational proteolitic cleavage Dmp1 exists within the extracellular matrix of bone and dentin as: an NH₂-terminal fragment, a COOH-terminal fragment and the proteoglycan form of the NH₂-terminal fragment (DMP1-PG). To begin to assess the biological function of each fragment we evaluated the distribution of both fragments in the rat tooth and bone using antibodies specific to the NH₂-terminal and COOH-terminal regions of DMP1 and confocal microscopy. In rat first molar organs, the NH₂-terminal fragment localized to predentin, whereas the COOH-terminal fragment was mainly restricted to mineralized dentin. In the growth plate of bone, the NH₂-terminal fragment appeared in the proliferation and hypertrophic zones, while the COOH-terminal fragment occupied the ossification zone. FRET analysis showed colocalization of both fragments of DMP1 in odontoblasts and predentin as well as hypertrophic chondrocytes within the growth plates of bone. The biochemical analysis of bovine teeth revealed that predentin is rich in DMP1-PG, whereas mineralized dentin primarily contains the COOH-terminal fragment. We conclude that the differential patterns of expression of NH₂-terminal and COOH-terminal fragments of DMP1 reflect their potentially distinct roles in the biomineralization of dentin and bone matrices.

Key Words: dentin matrix protein 1, immunolocalization, dentinogenesis, osteogenesis, Forster resonance energy transfer

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				A. Gericke, C. Qin, Y. Sun, R. Redfern, D. Redfern, Y. Fujimoto, H. Taleb, W.T. Butler, and A.L. Boskey Different Forms of DMP1 Play Distinct Roles in Mineralization Journal of Dental Research, April 1, 2010; 89(4): 355 - 359. [Abstract] [Full Text] [PDF]

Guidelines | Subscriptions | About | exPRESS - Current - Archive | Business Information | Contact

The Journal of Histochemistry & Cytochemistry is owned, published, and licensed by The Histochemical Society © 2008