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Ameloblastin

Enamel (E) is missing in mice that do not make ameloblastin (right).

Like dentures, real teeth also need some adhesive, according to Fukumoto et al. (page 973). Without this dental glue, teeth do not develop their protective enamel coating.

Enamel is made by ameloblasts, which differentiate from oral epithelial precursors. Most of the enamel matrix consists of amelogenin, but ameloblasts also secrete several other matrix proteins, including ameloblastin. Fukumoto et al. show that ameloblastin is a cellular adhesive needed to maintain ameloblast differentiation.

In mice lacking ameloblastin, ameloblasts formed as usual at early stages. But they later detached from their matrix at a time when the surface is normally replaced with enamel matrix proteins. The detached ameloblasts lost their cell polarity and returned to a less differentiated, proliferative state. The epithelium-derived oral tumors that were found in the adult mutant mice probably formed from these proliferative cells.

The cells detached because ameloblastin was not there to substitute for the basement membrane that was degraded during enamel secretion. Ameloblast precursors used the basement membrane as adhesive, but the differentiated ameloblasts bound only to ameloblastin. If the authors can identify the cell receptor for ameloblastin, they may be able to determine the signaling pathways that maintain differentiation in the matrix-adhered cells.

Nicole LeBrasseur

lebrasn{at}rockefeller.edu

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Related Article

Ameloblastin is a cell adhesion molecule required for maintaining the differentiation state of ameloblasts

Satoshi Fukumoto, Takayoshi Kiba, Bradford Hall, Noriyuki Iehara, Takashi Nakamura, Glenn Longenecker, Paul H. Krebsbach, Antonio Nanci, Ashok B. Kulkarni, and Yoshihiko Yamada
J. Cell Biol. 2004 167: 973-983. [Abstract] [Full Text] [PDF]

This Article Full Text (PDF, 641K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by LeBrasseur, N. Search for Related Content PubMed Articles by LeBrasseur, N. Related Collections Related Article Social Bookmarking                            What's this?