Matrix Protein Regulation of Enamel Mineral Formation

本项目的目的是阐明釉基质蛋白高阶集合体的结构和形成机制，以及它们对体外矿化和晶体结构的影响。我们认为，有组织的矿物结构是在基质蛋白质的有组织的超级组装中与其他指导晶体生长和形状的大分子合作产生的。我们的工作假设是，全长釉原蛋白的高阶集合与可溶性酸性蛋白(如釉蛋白和成釉蛋白)结合，调节初始釉质矿物晶体的成核、生长、形状和排列。在适当的成矿条件下，这种集合体支持形成非常薄的珐琅矿物带的平行阵列。这些釉质带在厚度和宽度上的生长立即被吸附在生长晶体的特定表面上的可溶性疏水性釉质蛋白(例如，稀有的可溶性釉质原蛋白)所抑制。进一步假设，这些矿物质带在组织中随后开始生长 成熟度是由特定的釉质蛋白酶降解这些釉质蛋白抑制物控制的。为了更好地理解基质蛋白如何调节牙釉质等组织中的矿化，我们建议根据特定的釉质基质成分形成最终调节有序矿化的高阶集合的能力来表征它们的特征。具体地说，我们建议表征关键的釉质基质蛋白与矿物表面结合的能力(目标1)，调节晶体形状和晶体生长的动力学(目标2)， 并在体外诱导磷酸钙形成(目标3)。重要的是，这些发现将与生物物理研究相结合，以确定拟议的全长釉质原蛋白的高阶集合体的结构和形成机制(目标4)，以及这种集合体调节类似于牙釉质的有序矿物结构的形成的机制(目标5)。从长远来看，这些信息应该为开发仿生材料和矿化组织修复和修复的新方法提供新的见解 再生。

The purpose of this project is to elucidate the structure and mechanism of formation of higher order assemblies of enamel matrix proteins and their influence on mineralization and crystal organization in vitro. We propose that organized mineral stuctures are generated within organized super-assemblies of matrix proteins in cooperation with other macromolecules that guide crystal growth and shape. Our working hypothesis is that higher order assemblies of full-length amelogenin, in association with soluble acidic proteins (e.g., enamelin and ameloblasrin), regulate the nucleation, growth, shape, and arrangement of initial enamel mineral crystals. Under appropriate mineralizing conditions, such assemblies support the formation of parallel arrays of very thin ribbons of enamel mineral. The growth of these enamel ribbons in thickness and width is immediately inhibited by soluble hydrophobic enamel proteins (e.g. sparingly soluble amelogenins) which adsorb onto specific faces of the growing crystals. It is further hypothesized that the subsequent onset of growth of these mineral ribbons during tissue maturation is controlled by the degradation of these enamel protein inhibitors by specific enamel proteinases. To improve our understanding of how matrix proteins regulate mineralization in tissues like enamel, we propose to characterize specific enamel matrix components with respect to their ability to form higher-order assemblies that ultimately regulate organized mineralization. Specifically, we propose to characterized the ability of key enamel matrix proteins to bind to mineral surfaces (Aim 1), to regulate crystal shape and kinetics of crystal growth (Aim 2), and to induce calcium phosphate formation in vitro (Aim 3). Importanly, these findings; will be integrated with biophysical studies to determine the structure and mechanism of formation of proposed higher order assemblies of the full-length amelogenin (Aim 4) and the mechanism by which such assemblies regulate the formation of organized mineral structures, similar to that of dental enamel (Aim 5). Long term, such information should provide new insights for the development of bio-inspired materials and novel approaches for mineralized tissue repair and regeneration.