Expression pattern of odontogenic ameloblast-associated and amelotin during formation and regeneration of the junctional epithelium

Abstract

The junctional epithelium (JE) adheres to the tooth surface, and seals off periodontal tissues from the oral environment. This incompletely differentiated epithelium is formed initially by the fusion of the reduced enamel organ with the oral epithelium (OE). Two proteins, odontogenic ameloblast-associated (ODAM) and amelotin (AMTN), have been identified in the JE. The objective of this study was to evaluate their expression pattern during formation and regeneration of the JE. Cytokeratin 14 was used as a differentiation marker for oral epithelial cells, and Ki67 for cell proliferation. Immunohistochemistry was carried out on erupting rat molars, and in regenerating JE following gingivectomy. In the reducing enamel organ and in established JE, ODAM and AMTN were present at the celltooth interface while only ODAM and CK14 were found throughout the JE. Both were also conspicuously present in cell clusters situated between the erupting tooth and OE. During JE regeneration, ODAM was detected first at the leading wound edge and then in the regenerating JE. Some cell clusters in the subjacent connective tissue were also positive for ODAM. AMTN appeared later and both AMTN and ODAM accumulated at the interface with the tooth. Cytokeratin 14 gradually appeared in the regenerating JE but the cell clusters showed variable labeling. Cells associated with JE formation and regeneration exhibited higher division activity than adjacent epithelial cells. These findings suggest that ODAM and AMTN have a role at the cell-tooth interface, and that ODAM is likely also implicated in cellular events during formation and regeneration of the JE.

Proinflammatory cytokines induce amelotin transcription in human gingival fibroblasts

“…It is of particular interest that AMTN and ODAM were upregulated to a similar extent; a recent study (20) showed that AMTN and ODAM are re-expressed during gingival regeneration, and both proteins have been shown to interact (21). Therefore it is conceivable that the regulation of AMTN and ODAM in gingival cells is not independent.…”

“…The JE adheres to the tooth surface, and seals off periodontal tissues from the oral environment. It is formed initially by fusion of the reduced enamel epithelium with the oral epithelium (20), and is connected to the enamel via an inner basal lamina and hemidesmosomes (22). Two proteins, AMTN and ODAM/APIN, have been identified in the JE (9)(10)(11).…”

Odontogenic ameloblast-associated and amelotin are novel basal lamina components

“…During regeneration of JE after gingivectomy, ODAM appears first and localizes at the interface as well as among cells. Expression of AMTN is protracted and the protein appears restricted to the interface (Nishio et al 2010). Odam and Amtn genes are members of the SCPP gene cluster which has arisen from a common ancestor-the secreted protein acidic rich in cysteine like 1 (SPARCL1) gene (Kawasaki and Weiss 2008).…”

“…Both are expressed mainly in the tooth where they are localized at cell-tooth interfaces (Moffatt et al 2006b(Moffatt et al , 2008Nishio et al 2010;Iwasaki et al 2005;Park et al 2007;SomogyiGanss et al 2011). ODAM was also shown to be highly expressed in some epithelial malignancies but not in corresponding healthy tissues Kestler et al 2008;Siddiqui et al 2009).…”

The junctional epithelium originates from the odontogenic epithelium of an erupted tooth

“…Several studies have reported that the JE originates not from the oral epithelium but from the reduced enamel epithelium, which is the odontogenic epithelium that remains around the enamel surface of an erupting tooth10111213141516. Similarly, Nanci et al showed that both odontogenic ameloblast-associated and amelotin were expressed in the JE171819. Therefore, it seems acceptable that the origin of JE is the reduced enamel epithelium at the initial stage of tooth eruption.…”