The origin and evolution of enamel mineralization genes.
OBJECTIVE
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.


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.


CONCLUSIONS
The evolutionary analysis of AMEL led to propose a dataset that will be useful to validate AMEL mutations leading to X- linked AI.
Sire
Jean-Yves
JY
UMR 7138, Université Pierre et Marie Curie-Paris 6, Paris, France. sire@ccr.jussieu.fr
Davit-Béal
Tiphaine
T
Delgado
Sidney
S
Gu
Xun
X
D053523:Amelogenin / Q000145:classification / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D002874:Chromosome Mapping; D003743:Dental Enamel / Q000254:growth & development* / Q000378:metabolism; D003746:Dental Enamel Proteins / Q000145:classification / Q000235:genetics / Q000502:physiology*; D019143:Evolution, Molecular; D020440:Gene Duplication; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D020539:Sequence Analysis, Protein; D014074:Tooth Calcification / Q000235:genetics*
C490889:AMBN protein, human; D053523:Amelogenin; D003746:Dental Enamel Proteins; C038456:tuftelin