Matrix Protein Regulation of Enamel Mineral Formation

本课题的目的是阐明釉基质蛋白的高级组装体的结构和形成机制，以及它们对体外矿化和晶体组织的影响。我们提出，有组织的矿物结构内产生有组织的超组装的基质蛋白质与其他大分子，指导晶体生长和形状的合作。我们的工作假设是，全长釉原蛋白的高阶组装体，与可溶性酸性蛋白（例如，釉质蛋白和成釉蛋白）调节初始釉质矿物晶体的成核、生长、形状和排列。在适当的矿化条件下，这种组装支持釉质矿物质的非常薄的条带的平行阵列的形成。这些釉质条带的厚度和宽度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釉质蛋白（例如，微溶的釉原蛋白）抑制。进一步假设，这些矿物带在组织生长过程中随后开始生长， 成熟是通过特定的釉质蛋白酶降解这些釉质蛋白抑制剂来控制的。为了提高我们对基质蛋白如何调节釉质等组织中矿化的理解，我们建议表征特定的釉质基质成分，以确定其形成最终调节有组织矿化的高阶组装体的能力。具体而言，我们提出表征关键釉质基质蛋白结合矿物表面的能力（目标1），调节晶体形状和晶体生长动力学的能力（目标2）， 并在体外诱导磷酸钙形成（目的3）。重要的是，这些发现;将与生物物理学研究相结合，以确定所提出的全长釉原蛋白的高级组装体的结构和形成机制（目标4），以及这些组装体调节类似于牙釉质的有组织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生物启发材料和矿化组织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.