Seminars and Special Events

Redesign of enamel biomineralization by protein engineering of amelogenin

Malcolm Snead, DDS, PhD
School of Dentistry
University of Southern California

Friday, November 11, 2005
3pm
Searle Foundation Room
Robert H. Lurie Medical Research Center

To create a bioceramic with unique materials properties, biomineralization exploits a tissue-specific protein matrix to control the crystal habit, timing and position of the mineral phase. The biomineralized covering of vertebrate teeth is enamel, a distinctive tissue of ectodermal origin that is collagen-free. Amelogenin is the abundant protein in forming enamel that undergoes self-assembly to contribute to a matrix that guides its replacement by mineral. Conserved domains in amelogenin suggest their importance to biomineralization. We used gene targeting in mice to replace native amelogenin with one of two engineered amelogenins. Replacement changed enamel organization by altering protein-to-crystallite interactions and crystallite stacking, while diminishing the ability of the ameloblast to interact with the matrix. These data demonstrate that ameloblasts must continuously interact with the developing matrix to provide amelogenin-specific protein to protein, protein to mineral and protein to membrane interactions critical to biomineralization and enamel architecture while suggesting that mutations within conserved amelogenin domains could account for enamel variations preserved in the fossil record.

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