Diekwisch Lab: Enamel Formation and Evolution

Our lab is interested in determining the molecular mechanisms that govern enamel formation. Early on, we discovered the functional significance of supramolecular enamel matrix organization for enamel development (Diekwisch et al. 1993). We also demonstrated the independence of enamel deposits from adjacent dentin (Diekwisch et al. 1995). In a series of evolutionary biology studies, we cloned and characterized a number of novel amelogenin genes, including frogs, salamanders, and iguanas in reptiles and amphibians (Wang et al. 2005, Diekwisch et al. 2006, Wang et al. 2006, Diekwisch et al. 2009, Wang et al. 2014). Based on these studies, we established polyproline repeat elongation as a mechanism for amelogenin aggregate compaction and enamel crystal elongation (Jin et al. 2009, PLoS Biology). Finally our lab reported the first complete 3D structure of the major tooth enamel protein, amelogenin (Zhang et al. 2011). Currently, we are asking how mineral ions are transported toward the enamel layer and what factors govern the nucleation and elongation of enamel crystals. Using an evolutionary biology approach, we are now studying the relationship between the amelogenin molecule and enamel mechanical properties.

Decussating enamel rods. Tooth enamel is a tissue of extraordinary three-dimensional architecture. The electron micrograph illustrates the packing of groups of parallel oriented enamel crystals into cylindrical rods, which in turn are organized into an amazing decussating pattern that greatly contributes to resilience and strength.

 

Contributions to Journals

Lucas, P.W., Casteren, A.v., Al-Fadhalah, K., Almusallam, A.S., Henry, A.G., Michael, S., Watzke, J., Reed, D.A., Diekwisch, T.G.H., Strait, D.S. and Atkins, A.G. (2014). The role of dust, grit and phytoliths in tooth wear. Annales Zoologici Fennici 51, 143-152.

Wang, X., Xing, Z., Zhang, X., and Diekwisch, T.G.H. (2013). Alternative splicing of the amelogenin gene in a caudate amphibian Plethodon cinereus. PLoS ONE 8(6): e68965. doi:10.1371/journal.pone.0068965.

Atsawasuwan, P., Lu, X., Ito, Y., Chen, Y., Evans, C.A., Kulkarni, A.B., Gibson, C.W., Luan, X., and Diekwisch, T.G.H. (2013). Enamel-related gene products in calvarial development. J. Dent. Res. 92, 622-628.

Lu, X., Ito, Y, Kulkarni, A., Gibson, C., Luan, X., and Diekwisch, T.G.H. (2011). Ameloblastin-rich enamel matrix favors short and randomly oriented apatite crystals. Eur. J Oral Sci 119, 254-260. Journal Cover.

Zhang, X., Diekwisch, T.G.H., and Luan, X. (2011). Structure and function of ameloblastin as an extracellular matrix protein: Adhesion, calcium binding, and CD63-interaction in human and mouse. Eur. J Oral Sci 119, 270-279.

Zhang, X., Ramirez, B., Liao, X., and Diekwisch, T.G.H. (2011). Amelogenin Supramolecular Assembly in Nanospheres Defined by a Complex Helix-Coil-PPII helix 3D-Structure. PLoS ONE 6(10): e24952. doi:10.1371/journal.pone.0024952.

Wright, T, and Diekwisch, T.G.H. (2011). Foreword, Enamel VIII. Eur J Oral Sci 119,x-xi.

Diekwisch, T.G.H. (2011). Evolution and ameloblastin. Edited Discussion, Enamel VIII. Eur J Oral Sci 119, 293-297.

Jin, T.*, Ito, Y.*, Luan, X., Dangaria, S., Walker, C., Allen, M., Kulkarni A., Gibson, C., Braatz, R., Liao, X., and Diekwisch, T.G.H. (2009). Supramolecular compaction through polyproline motif elongation as a mechanism for vertebrate enamel evolution. PLoS Biology 7(12): e1000262. doi:10.1371/journal.pbio.1000262. Featured in Science: ScienceNOW/ScienceShots December 2009.

Diekwisch, T.G.H., Jin, T., Wang, X., Ito, Y., Schmidt, M.K., Druzinsky, R., Yamane, A., and Luan, X. (2009). Amelogenin evolution and tetrapod enamel structure. Frontiers of Oral Biology 13, 74-79.

Wang, X., Fan, J.-L., Ito, Y., Luan, X., and Diekwisch, T.G.H. (2006). Identification and characterization of a squamate reptilian amelogenin gene: Iguana iguana. J. Exp. Zool. Mol. Dev. Evol. 305B, 393-406.

Diekwisch, T.G.H., Wang, X., Fan, J.-L., Ito, Y., and Luan, X. (2006). Expression and characterization of a Rana pipiens amelogenin protein. Eur. J. Oral Sci. 114, 86-92.

Wang, X., Ito Y., Luan, X., Yamane, A., and Diekwisch, T.G.H. (2005). Amelogenin sequence and enamel biomineralization in Rana pipiens. J. Exp. Zool. Mol. Dev. Evol. 304B:1-10.

Diekwisch, T.G.H., Berman, B.J., Anderton, X., Gurinsky, B., Ortega A.J., Satchell P.G., Williams, M., Arumugham C., Luan X., McIntosh J.E., Yamane A., Carlson, D.S., Sire, J.-Y., Simmer J.P., and Shuler, C.F. (2002). Membranes, minerals, and proteins of developing vertebrate enamel. Microscopy Research Technique 59, 373-395.

Satchell, P.G., Anderton, X., Ryu, O.H., Luan, X., Ortega, A.J., Opamen, R., Berman, B.J., Witherspoon, D.E., Gutmann, J.L., Yamane, A., Zeichner-David, M., Simmer, J.P., Shuler, C.F., and Diekwisch, T.G.H. (2002). Conservation and variation in enamel protein distribution during tooth development across vertebrates. Mol. Dev. Evol. J. Exp. Zool. 294, 91-106.

Satchell, P.G., Shuler, C.F., and Diekwisch, T.G.H. (2000). True enamel covering in teeth of the Australian lungfish Neoceratodus forsteri. Cell & Tiss. Res. 299, 27-37. Journal Cover.

Thieberg, R.H., Yamauchi, M., Satchell, P.G., and Diekwisch, T.G.H. (1999). Sequential distribution of keratan sulfate and chondroitin sulfate epitopes during ameloblast differentiation. Histochem. J. 31, 573-578.

Diekwisch, T.G.H. (1998). Subunit compartments of secretory stage enamel matrix. Conn. Tiss. Res. 38, 101-111.

Zeichner-David, M., Vo. H., Tan, H., Diekwisch, T., Berman, B., Thiemann, F., Alcocer, M.D., Hsu, P., Wang, T., Reyna, J., Caton, J., Slavkin, H.C., and MacDougall, M. (1997). Timing of the expression of enamel gene products during mouse tooth development. Int. J. Dev. Biol. 41, 27-38.

Diekwisch, T.G.H., Ware, J., Fincham, A.G., and Zeichner-David, M. (1997). Immunohistochemical similarities and differences between amelogenin and tuftelin gene products during tooth development. J. Histochem. Cytochem. 40, 859-866.

Slavkin, H.C. and Diekwisch, T.G. (1997). Molecular strategies of tooth enamel formation are highly conserved during vertebrate evolution. Ciba Found Symp. 205, 73-80.

Slavkin, H.C. and Diekwisch, T. (1996). Evolution in tooth developmental biology: of morphology and molecules. Anat. Rec. 245, 131-150.

Fincham, A.G., Moradian-Oldak, J., Diekwisch, T.G.H., Lyaruu, D.M., Wright, J.T., Bringas, P., Jr., and Slavkin, H.C. (1995). Evidence for amelogenin “nanospheres” as functional components of secretory-stage enamel matrix. J. Struct. Biol. 115, 50-59.

Moradian-Oldak, J., Simmer, J.P., Lau, E.C., Diekwisch, T., Slavkin, H.C., and Fincham, A.G. (1995). A review of the aggregation properties of a recombinant amelogenin. Connect. Tiss. Res. 32, 125-130.

Zeichner-David, M., Diekwisch, T., Fincham, A., Lau, E., Mac Dougall, M., Moradian-Oldak, J., Simmer, J., Snead, M., and Slavkin, H.C. (1995). Control of Ameloblast Differentiation. J.-V. Ruch (Ed.), Odontogenesis: Embryonic dentition as a tool for developmental biology. Int. J. Dev. Biol. 39, 69-92.

Diekwisch, T.G.H., Berman, B.J., Gentner, S., and Slavkin, H.C. (1995). Initial enamel crystals are spatially not associated with mineralized dentine. Cell & Tissue 279, 149-167. Journal Cover.

Diekwisch, T.G.H., Marches, F., Spears, R., and Dechow, P. (1995). Effect of enamel protein expression on enamel crystal formation: a phylogenetic study. R.J. Radlanski and H. Renz (Eds.) Proc. 10th Int. Symp. Dent. Morph., Berlin 1995, pp. 82-87

Fincham, A.G., Moradian-Oldak, J. Simmer, J.P., Sarte, P., Lau, E.C., Diekwisch, T., and Slavkin, H.C. (1994). Self-assembly of a recombinant amelogenin protein generates supramolecular structures. J. Struct. Biol. 112, 103-109.

Diekwisch, T., David, S., Bringas, P., Santos, V. and Slavkin, H.C. (1993). Antisense inhibition of AMEL translation demonstrates supramolecular controls for enamel HAP crystal growth during embryonic mouse molar development. Development 117, 471-482.

Diekwisch, T. (1989). Localization of microfilaments and microtubules during dental Development in the rat. Acta histochemica 37, 209-212.

 

Architecture of the amelogenin gene. Amelogenin is the principle protein within the enamel matrix. It is encoded by a number of exons, the largest of which, exon 6, contributes to about one half of the protein and contains the central hydrophobic core of the molecule. The hydrophobic core is flanked by a tyrosine-rich N-terminus and a hydrophilic C-terminus. The amelogenin gene is one of the textbook examples of alternative splicing, and spliced products are subject to further posttranslational modifications and processing, resulting in the TRAP and LRAP peptides which are abundant in the enamel matrix.