Moradian-Oldak J
Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, 2250 Alcazar St., Los Angeles, CA 90033, USA.
Matrix Biol. 2001 Sep;20(5-6):293-305. doi: 10.1016/s0945-053x(01)00154-8.
The remarkable properties of enamel crystals and their arrangements in an extraordinary micro-architecture are clear indications that the processes of crystal nucleation and growth in the extracellular matrix are highly controlled. The major extracellular events involved in enamel formation are: (a) delineation of space by the secretory ameloblasts and the dentino-enamel junction; (b) self-assembly of amelogenin proteins to form the supramolecular structural framework; (c) transportation of calcium and phosphate ions by the ameloblasts resulting in a supersaturated solution; (d) nucleation of apatite crystallites; and (e) elongated growth of the crystallites. Finally, during the 'maturation' step, rapid growth and thickening of the crystallites take place, which is concomitant with progressive degradation and eventual removal of the enamel extracellular matrix components (mainly amelogenins). This latter stage during which physical hardening of enamel occurs is perhaps unique to dental enamel. We have focused our in vitro studies on three major extracellular events: matrix assembly, matrix processing and control of crystal growth. This paper summarizes current knowledge on the assembly, processing and effect on crystal morphology by amelogenin proteins. The correlation between these three events and putative functional roles for amelogenin protein are discussed.
牙釉质晶体的显著特性及其在非凡微观结构中的排列清楚地表明，细胞外基质中晶体的成核和生长过程受到高度控制。牙釉质形成过程中涉及的主要细胞外事件包括：(a) 分泌性成釉细胞和牙本质-牙釉质界划定空间；(b) 釉原蛋白自组装形成超分子结构框架；(c) 成釉细胞运输钙和磷酸根离子形成过饱和溶液；(d) 磷灰石微晶成核；(e) 微晶的伸长生长。最后，在“成熟”阶段，微晶快速生长和增厚，同时牙釉质细胞外基质成分（主要是釉原蛋白）逐渐降解并最终被去除。牙釉质发生物理硬化的这一后期阶段可能是牙釉质所特有的。我们的体外研究集中在三个主要的细胞外事件上：基质组装、基质加工和晶体生长控制。本文总结了目前关于釉原蛋白在组装、加工及对晶体形态影响方面的知识。讨论了这三个事件与釉原蛋白假定功能作用之间的相关性。
