Enamel Mineral Formation during Murine Odontogenesis

描述（由申请人提供）：淀粉原蛋白在正常牙釉质的发育中起着重要作用。这方面的证据来自于淀粉原蛋白（AMELX）基因突变的患者，他们患有珐琅质缺陷淀粉原性不完全性（AI），以及AMELX缺失小鼠，它们的情况与x连锁型AI类似。与人类患者中发现的各种类型的AI相对应的Null和转基因小鼠模型已经开始揭示正常和突变的牙釉质蛋白的作用。缺乏基质金属蛋白酶-20 （MMP-20）的小鼠也有类似于人类AI的牙釉质缺陷，这是由于在发育过程中缺乏淀粉原蛋白和其他牙釉质蛋白的蛋白水解加工。这些动物模型提供了关于人类发育基本过程的信息，因为啮齿动物和人类牙釉质蛋白质、矿物质和牙齿发育在总体上存在相似性。在这一竞争性更新应用中，我们提出了以下目标：(i)利用光镜、扫描电镜和透射电镜分析具有Amelx null基因组突变的转基因小鼠的修复釉质表型，以确定180和59个氨基酸的amelogenin蛋白的作用；（ii）对正常和突变的Amelx null、MMP20 null和Amelx null小鼠的釉质厚度、结构、晶体尺寸和取向进行评价，以了解Amelx原蛋白c端在体内的作用；（iii）确定遗传背景在观察到的空白小鼠牙釉质表型异质性中的作用；（iv）采用跨学科方法，利用不同牙釉质缺陷分类的小鼠模型，研究不同牙釉质基因突变患者的牙釉质粘接治疗方法。在这项工作的结论中，更好地了解单个淀粉原蛋白在牙釉质发育过程中的功能，并深入了解其他蛋白质在疾病严重程度中所起的作用，将导致针对不同AI突变个体设计新的治疗方法。这种基础和临床方法的结合将产生基础知识以及转化应用，通过提供与基因改变相对应的治疗方法，从而改善牙齿/口腔健康，从而使公众受益。项目描述：牙釉质缺陷患者经常因为牙齿的外观而延长临床治疗，疼痛和社交焦虑。了解遗传基因突变是如何导致牙釉质缺陷的，将有助于了解牙釉质是如何发展的，并为如何防止结构缺陷的发展提供更多的线索。小鼠模型模拟人类缺陷，可用于将个体基因突变与适当的临床干预相关联。项目的叙述

DESCRIPTION (provided by applicant): The amelogenin proteins have a fundamental role in development of normal dental enamel. Evidence for this comes from patients with mutations in the amelogenin (AMELX) gene, who have the enamel defect amelogenesis imperfecta (AI), and from Amelx null mice, which have a condition similar to the X-linked form of AI. Null and transgenic murine models that correspond to various types of AI identified in human patients have begun to reveal roles of both the normal and mutated enamel proteins. Mice null for matrix metalloproteinase-20 (MMP-20) also have an enamel defect similar to a human AI, due to deficiency in proteolytic processing of amelogenins and other enamel proteins during development. These animal models provide information concerning basic processes in human development because of similarities between rodent and human enamel proteins, mineral and dental development in general. In this competitive renewal application, we propose the following aims: (i) To analyze the rescued enamel phenotype in transgenic mice with an Amelx null genomic mutation to determine roles of the 180 and 59 amino acid amelogenin proteins, using light, scanning and transmission electron microscopy; (ii) To evaluate enamel thickness, structure and crystal dimensions and orientation in the Amelx null, MMP20 null, and Amelx null mice with normal and mutated amelogenin transgenes for fundamental information about the role of the amelogenin C-terminus in vivo; (iii) To determine the role of genetic background in the observed enamel phenotypic heterogeneity in null mice; and (iv) To use murine models with different classifications of enamel defects in an interdisciplinary approach to develop enamel bonding treatments for AI in patients with different enamel gene mutations. At the conclusion of this work, a better understanding of the function of individual amelogenins during enamel development, and insight into the role that other proteins play in disease severity, will lead to new treatments designed for individuals with different AI mutations. This combination of basic and clinical approaches will generate fundamental knowledge as well as translational application that will benefit the public by providing therapeutic approaches that correspond to genetic alterations, leading to improved dental/oral health. Project Narrative: Patients with defective enamel frequently have prolonged clinical treatment, pain and social anxiety because of the appearance of their teeth. An understanding of how inherited gene mutations cause enamel defects will lead to insight into how enamel develops and shed more light on how to prevent structural defects from developing. Mouse models mimic the human defects and can be used to correlate individual gene mutations with appropriate clinical intervention. Project Narrative Patients with defective enamel frequently have prolonged clinical treatment, pain and social anxiety because of the appearance of their teeth. An understanding of how inherited gene mutations cause enamel defects will lead to insight into how enamel develops and shed more light on how to prevent structural defects from developing. Mouse models mimic the human defects and can be used to correlate individual gene mutations with appropriate clinical intervention.