MMP-20 AND MMP-20 DOMAIN FUNCTION IN FORMING ENAMEL

描述(由申请人提供)：本申请的目标是 基质金属蛋白酶釉质溶解蛋白(MMP20)的作用 在牙釉质和牙齿发育过程中发挥作用。釉质蛋白 (成釉蛋白、成釉蛋白、釉质蛋白)在分泌后不久即被切割 进入牙釉质基质。釉质溶血素与釉质同时表达 蛋白质和重组釉原蛋白将在 几乎所有以前在活体内观察到的精确位置。因此， 釉质溶素是一种重要的釉原蛋白加工酶。至于所有的MMP， 釉质溶素含有一种必须被切割的前肽，如果该酶 变得活跃起来。釉质溶素也有一个没有功能的血凝蛋白结构域 定义得很清楚。一种釉质溶蛋白基因敲除(-/-)小鼠被设计成 釉质溶解蛋白对牙齿和釉质发育的贡献(目标1)。这个 釉质溶素-/-鼠是唯一一只具有深刻表型的基质金属蛋白酶-/-鼠 存活下来繁衍后代。因此，我们可以定义釉解素启动子的界限。 (目的2)以使其可用于在-/-中表达釉溶素转基因 背景，并将-/-表型恢复到正常。此外，因为 -/-小鼠具有深刻的表型并能繁殖，我们拥有 唯一可以用来描述这种机制的基质金属蛋白酶-/-鼠 基质金属蛋白酶前肽和/或血凝蛋白结构域的功能。因此，我们建议 将两个釉质溶素启动子转基因到-/-背景中。第一 转基因将使釉质溶素以活性酶(前肽)的形式分泌 细胞内去除)，以便我们可以表征釉质裂解素的作用 牙齿发育中的前肽(目标3)。第二个转基因将编码 釉质溶血素没有其‘Hopexin结构域，因此对 牙齿发育中的血凝蛋白结构域可被描述(目标4)。这个 该项目的长期目标是促进对 釉质形成，最终合成釉质可以被设计用于 修复受损(龋齿)或患病(釉质形成不全)的牙齿 珐琅。此应用程序构建在高效R29拨款的结果之上 (DE12098)。

DESCRIPTION (provided by applicant): The goal of this application is to characterize the role that the matrix metalloproteinase enamelysin (MMP-20) plays during dental enamel and tooth development. The enamel proteins (amelogenin, ameloblastin, enamelin) are cleaved soon after they are secreted into the enamel matrix. Enamelysin is expressed simultaneously with the enamel proteins and recombinant enamelysin will cleave recombinant amelogenin at virtually all of the precise sites previously observed in vivo. Thus, enamelysin is an important amelogenin processing enzyme. As for all MMPs, enamelysin contains a propeptide that must be cleaved if the enzyme is to become active. Enamelysin also has a hemopexin domain that is not functionally well defined. An enamelysin knockout (-/-) mouse was engineered to characterize the contribution of enamelysin to tooth and enamel development (Aim 1). The enamelysin -/-mouse is the only MMP -/- mouse with a profound phenotype that survives to breed. Thus, we can define the limits of the enamelysin promoter (Aim 2) so that it may be used to express an enamelysin transgene in the -/- background and revert the -/- phenotype back to normal. Furthermore, because the -/- mouse has a profound phenotype and can breed, we are in possession of the only MMP -/- mouse that can be utilized to characterize the mechanistic function of the MMP propeptide and/or hemopexin domain. So, we propose to introduce two enamelysin promoter transgenes into the -/-background. The first transgene will allow enamelysin to be secreted as an active enzyme (propeptide removed intracellularly) so that we may characterize the role of the enamelysin propeptide in tooth development (Aim 3). The second transgene will encode enamelysin without its' hemopexin domain so that the contribution of the hemopexin domain in tooth development may be characterized (Aim 4). The long-term goals of this project are to contribute to the understanding of enamel formation so that eventually synthetic enamel can be engineered for the repair of damaged (dental caries) or diseased (amelogenesis imperfecta) dental enamel. This application builds on results from a highly productive R29 grant (DE12098).