Relationships between protein and mineral during enamel development in normal and genetically altered mice

Authors

  • Charles E. Smith,

    1. Facility for Electron Microscopy Research, Department of Anatomy & Cell Biology, and Faculty of Dentistry, McGill University, Montreal, QC, Canada
    2. Dental Research Laboratory, Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
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  • Yuanyuan Hu,

    1. Dental Research Laboratory, Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
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  • Amelia S. Richardson,

    1. Dental Research Laboratory, Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
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  • John D. Bartlett,

    1. Department of Cytokine Biology, Forsyth Institute and Department of Developmental Biology, Harvard School of Dental Medicine, Cambridge, MA, USA
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  • Jan C-C. Hu,

    1. Dental Research Laboratory, Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
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  • James P. Simmer

    1. Dental Research Laboratory, Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
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Charles E. Smith. Department of Anatomy & Cell Biology, McGill University, 3640 University Street, Montreal, QC, Canada H3A 2B2
Telefax: +1–514–3985047
E-mail: charles.smith@mcgill.ca

Abstract

Smith CE, Hu Y, Richardson AS, Bartlett JD, Hu JC-C, Simmer JP. Relationships between protein and mineral during enamel development in normal and genetically altered mice.
Eur J Oral Sci 2011; 119 (Suppl. 1): 125–135. © 2011 Eur J Oral Sci

The purpose of this study was to quantify and compare the amounts of volatiles (mostly protein) and mineral present in developing incisor enamel in normal mice and in those genetically engineered for absence of intact enamelin, ameloblastin, matrix metalloproteinase 20 (MMP20) or kallikrein-related peptidase 4 (KLK4). Data indicated that all mice showed peaks in the gross weight of volatiles and a similar weight of mineral at locations on incisors normally associated with early maturation. Thereafter, the content of volatiles on normal incisors declined rapidly by as much as 62%, but not by 100%, over 2 mm, accompanied by increases of ∼threefold in mineral weights. Enamelin heterozygous mice (lower incisors) showed a decrease in volatile content across the maturation stage, yet mineral failed to increase significantly. Mmp20 null mice showed no significant loss of volatiles from maturing enamel, yet the amount of mineral increased. Klk4 null mice showed normal mineral acquisition up to early maturation, but the input of new volatiles in mid to late maturation caused the final mineralization to slow below normal levels. These results suggest that it is not only the amount of protein but also the nature or type of protein or fragments present in the local crystallite environment that affects their volumetric expansion as they mature.

Ancillary