Matrix Protein Regulation of Enamel Mineral Formation

本项目旨在阐明牙釉质基质蛋白高阶组装体的结构、形成机制及其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是在基质蛋白的有组织的超级组装中与其他大分子合作产生的，这些大分子指导晶体生长和形状。我们的工作假设是全长釉原蛋白的高阶组合，与可溶性酸性蛋白（如釉素和成釉蛋白）结合，调节初始釉质矿物晶体的成核、生长、形状和排列。在适当的矿化条件下，这种组合支持形成非常薄的搪瓷矿物带的平行阵列。这些珐琅带在厚度和宽度上的生长立即被可溶性疏水性珐琅蛋白（例如，少量可溶性淀粉原蛋白）所抑制，这些蛋白吸附在生长晶体的特定表面上。进一步的假设是，这些矿物带在组织中随后开始生长

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.