The process of biomineralization has been widespread in both vertebrates for several hundred million years. Although the strategies used are complex and diverse, some aspects of mineralization may have been universally conserved throughout evolution in a very diverse range of organisms. Invertebrates comprise about 95% of animal species, yet a substantial body of work relates to mineralization in vertebrates. In vertebrate bone and dentine, apatite crystals are specifically grown within type I collagen matrices. The basic working hypothesis has been that certain acid, phosphorylated, non-collagenous extracellular matrix proteins (NCP) are localized by an interaction with collagen I fibril surfaces, and then direct the nucleation of crystal deposition and orientation of the crystal axes relative to the fibril axes. Further interactions of the NCPs with the growing crystals are postulated to specifically regulate crystal growth in terms of habit, shape, and size. Although bone and dentin share many NCPs, dentin appears to contain several unique, NCPs (e.g., DMP1, phosphophoryns [PP, DSP) that play a role in mineralization. The mineralized compartments of invertebrates do not contain collagen, but do have polymeric components that play an equivalent role. Moreover, several studies have shown that invertebrate mineralized tissues may have acid proteins which are the counterparts of the vertebrate NCPs. Teeth and exoskeletal denticles are among the most primitive vertebrate mineralized tissues. With the molecular tools now available, probes for specific acidic proteins could be used to explore relationships between various vertebrate and invertebrate species. We have chosen to investigate the phosphoryns of invertebrate (sea urchin) teeth, bichir scales and human dentin in order to enhance our comprehension of evolutionary processes that may reveal a similarity and/or diversity of NCPs throughout time. mRNA extract from human teeth, bichir scales and different portions of the sea urchin tooth will be used to create cDNA libraries. These libraries will be probed for the expression of DMP1, DMP2, and DMP3. The libraries will also be probed for bone NCPs such as ON, OPN, BGP and BSP. Antibodies for phosphophoryn will be used to relate expression of phosphophoryn or related proteins in human dentin, bichir scales and different portions of the sea urchin tooth. In addition, the biochemistry of the proteins found in these tooth related organs will be compared through extraction, purification and acidic protein content and composition.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08DE000424-02
Application #
6379685
Study Section
NIDCR Special Grants Review Committee (DSR)
Program Officer
Lipton, James A
Project Start
2000-05-01
Project End
2003-04-30
Budget Start
2001-05-01
Budget End
2002-04-30
Support Year
2
Fiscal Year
2001
Total Cost
$122,394
Indirect Cost
Name
Northwestern University at Chicago
Department
Dentistry
Type
Schools of Dentistry
DUNS #
005436803
City
Chicago
State
IL
Country
United States
Zip Code
60611
Sarlani, Eleni; Farooq, Naila; Greenspan, Joel D (2003) Gender and laterality differences in thermosensation throughout the perceptible range. Pain 106:9-18
Stock, S R; Barss, J; Dahl, T et al. (2003) Synchrotron X-ray studies of the keel of the short-spined sea urchin Lytechinus variegatus: absorption microtomography (microCT) and small beam diffraction mapping. Calcif Tissue Int 72:555-66
Stock, S R; Ignatiev, K; Dahl, T et al. (2003) Multiple microscopy modalities applied to a sea urchin tooth fragment. J Synchrotron Radiat 10:393-7
Stock, S R; Barss, J; Dahl, T et al. (2002) X-ray absorption microtomography (microCT) and small beam diffraction mapping of sea urchin teeth. J Struct Biol 139:1-12
Veis, Arthur; Barss, Joseph; Dahl, Thomas et al. (2002) Mineral-related proteins of sea urchin teeth: Lytechinus variegatus. Microsc Res Tech 59:342-51