The Origin and Evolution of Enamel Mineralization Genes

Abstract

Background/Aims: Enamel and enameloid were identified in early jawless vertebrates, about 500 million years ago (MYA). This suggests that enamel matrix proteins (EMPs) have at least the same age. We review the current data on the origin, evolution and relationships of enamel mineralization genes. Methods and Results: Three EMPs are secreted by ameloblasts during enamel formation: amelogenin (AMEL), ameloblastin (AMBN) and enamelin (ENAM). Recently, two new genes, amelotin (AMTN) and odontogenic ameloblast associated (ODAM), were found to be expressed by ameloblasts during maturation, increasing the group of ameloblast-secreted proteins to five members. The evolutionary analysis of these five genes indicates that they are related: AMEL is derived from AMBN, AMTN and ODAM are sister genes, and all are derived from ENAM. Using molecular dating, we showed that AMBN/AMEL duplication occurred >600 MYA. The large sequence dataset available for mammals and reptiles was used to study AMEL evolution. In the N- and C-terminal regions, numerous residues were unchanged during >200 million years, suggesting that they are important for the proper function of the protein. Conclusion: The evolutionary analysis of AMEL led to propose a dataset that will be useful to validate AMEL mutations leading to X- linked AI.

FAM20C Plays an Essential Role in the Formation of Murine Teeth

“…The SCPP proteins include SIBLINGs (small integrin-binding ligand, N-linked glycoproteins) (18), which comprise osteopontin, DMP1, BSP, matrix extracellular phosphoglycoprotein, and DSPP. The SCPP family also includes the enamel matrix proteins: ODAM, AMTN, AMBN, and ENAM (19). In this study, we characterized the teeth of the Sox2-Cre-mediated Fam20C knock-out mice; the teeth of these mice showed severe defects in dentin, enamel, and cementum, which might be attributed to failures in the posttranslational phosphorylations of some secretory proteins in the SCPP family.…”

Targeting the Sonic Hedgehog Pathway in Keratocystic Odontogenic Tumor

“…We also showed that these KCOT-derived cells express major dental epithelial cell markers: AMELX, ENAM, AMBN, and AMTN. These major EMPs have been shown to have preferential expression in dental tissues, in particular the developing enamel producing ameloblasts (24). Prior studies have determined the localization of apoptosis and proliferation markers and an invasion-associated enzyme heparanase (25,26).…”

Expression of Odontogenic Ameloblast-Associated Protein (ODAM) in Dental and Other Epithelial Neoplasms

“…Seemingly, this short ODAM protein would be deficient in a secretory signal sequence and presumably would remain within the cell where it could have a more restrictive or differing functional role from that of the larger ODAM product. Notably, the gene encoding ODAM has been predicted to evolve from those specifying enamelin and other evolutionarily-derived dental components, for example, amelogenin and amelotin, where alternative splicing occurs (29)(30)(31); this phenomenon has been documented in over 60% of human and mouse genes (32).…”