The amelogenin "enamel proteins" and cells in the periodontium

This overview will examine the multifunctional nature of a group of proteins known as the amelogenins. These secreted proteins were named in the 1960s because of their expected role during development of dental enamel [Eastoe JE. Adv Fluorine Res. 1965;21:5-17]. As gene expression assays became more sensitive, expression was also noted in tissues not involved with enamel formation leading to hypotheses concerning additional roles for these proteins. In vitro approaches led to the discovery that some of the amelogenins are able to regulate gene expression and to participate in cellular signaling. An extract containing predominately amelogenins has been used clinically in treatment of certain forms of pcriodontal disease with regenerative results noted originally in animal models, but later in human patients as well. Much literature has been devoted to the roles of amelogenins during mineral formation, and therefore this topic will be covered primarily in the Introduction. The goal of this review will be to focus on strategies that have been used to uncover roles of amelogenins related to gene expression and development apart from the roles in enamel mineral, and the possible functions that these proteins could have if delivered to normally nonexpressing tissues for therapeutic approaches.