Enamel Mineral Formation during Murine Odontogenesis

描述（由申请人提供）：釉原蛋白在正常牙釉质发育中具有重要作用。这一点的证据来自于有釉原蛋白（AMELX）基因突变的患者，他们患有釉质缺陷性成釉障碍（AI），以及来自Amelx缺失小鼠，它们的状况类似于X连锁形式的AI。与人类患者中鉴定的各种类型AI相对应的转基因小鼠模型已经开始揭示正常和突变的釉质蛋白的作用。基质金属蛋白酶-20（MMP-20）无效的小鼠也具有类似于人类AI的釉质缺陷，这是由于在发育期间缺乏釉原蛋白和其他釉质蛋白的蛋白水解加工。这些动物模型提供了有关人类发育基本过程的信息，因为啮齿动物和人类的釉质蛋白、矿物质和牙齿发育之间具有相似性。在这个竞争性更新应用中，我们提出了以下目的：（i）使用光学、扫描和透射电子显微镜分析具有Amelx无效基因组突变的转基因小鼠中的获救釉质表型，以确定180和59个氨基酸的釉原蛋白蛋白的作用;（ii）评价Amelx null、MMP 20 null、和具有正常和突变的釉原蛋白转基因的Amelx缺失小鼠，以获得关于釉原蛋白C-末端在体内作用的基本信息;（iii）确定遗传背景在无效小鼠中观察到的釉质表型异质性中的作用;及（iv）以跨学科的方法使用具有不同分类的釉质缺损的小鼠模型来开发针对具有不同釉质基因突变的患者的AI的釉质粘结治疗。在这项工作的结论中，更好地了解个体釉原蛋白在釉质发育过程中的功能，以及了解其他蛋白质在疾病严重程度中的作用，将导致为具有不同AI突变的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翻译应用，通过提供与遗传改变相对应的治疗方法使公众受益，从而改善牙齿/口腔健康。项目叙述：由于牙齿的外观，有缺陷的牙釉质患者通常会延长临床治疗，疼痛和社交焦虑。了解遗传性基因突变如何导致釉质缺陷将有助于深入了解釉质如何发育，并为如何防止结构缺陷的发展提供更多信息。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。

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.