Ameloblastin-rich enamel matrix favors short and randomly oriented apatite crystals. Academic Article uri icon


  • Molecular evolution studies suggest that amelogenin (AMELX), the principal component of the mammalian enamel matrix, emerged considerably later than ameloblastin (AMBN), and enamelin. Here, we created a transgenic mouse model to ask the question how a conceivable basal enamel lacking AMELX and enriched in the more basal AMBN might compare with recent mouse enamel. To answer this question we overexpressed AMBN using a keratin 14 (K14) promoter and removed AMELX from the genetic background by crossbreeding with amelx(-/-) mice. Enamel coverings of amelx(-/-) mice and of the squamate Iguana iguana were used for comparison. Scanning electron microscopic analysis documented that AMBN transgenic (TG) amelx(-/-) mouse molars were covered by a 5 m thin 'enameloid' layer resembling the thin enamel of the Iguana squamate. Transmission electron microscopy revealed that the enamel of developing AMBN TG amelx(-/-) mouse molars contained short (approximately 70 nm) and randomly oriented crystals, while WT controls, AMBN overexpressors, and AMELX(-/-) mice all featured elongated and parallel oriented crystals measuring between 300 and 600 nm in average length. Together, these studies illustrate that AMBN promotes the growth of a crystalline enamel layer with short and randomly oriented crystals, but lacks the ability to facilitate the formation of long and parallel oriented apatite crystals.

published proceedings

  • Eur J Oral Sci

author list (cited authors)

  • Lu, X., Ito, Y., Kulkarni, A., Gibson, C., Luan, X., & Diekwisch, T.

citation count

  • 18

complete list of authors

  • Lu, Xuanyu||Ito, Yoshihiro||Kulkarni, Ashok||Gibson, Carolyn||Luan, Xianghong||Diekwisch, Thomas GH

publication date

  • January 2011