ENAMEL MINERAL FORMATION DURING MURINE ODONTOGENESIS

釉原蛋白是由成釉细胞产生的细胞外基质蛋白 在牙釉质形成期间。 这些蛋白质是釉质所特有的， 是釉质矿物质正常发育所必需的。 本申请旨在研究X- 染色体釉原蛋白基因，通过分析3.5 KB片段， 在转基因小鼠中成釉细胞中直接表达报告基因， 序列分析和测试选定的活动片段， 转基因小鼠 我们还将在体内产生小鼠无效突变， 釉原蛋白基因，并表达富含亮氨酸釉原蛋白（RAP）， 转基因小鼠釉质，以确定过表达是否会干扰 釉原蛋白的正常功能。 击倒的交配 而LRAP小鼠将产生分泌LRAP的后代， 釉原蛋白在发育中的釉质中的作用。 具体目标是：（1） 表征X染色体釉原蛋白的调节序列 基因，使用转基因小鼠;（2）构建一个“敲除”小鼠， X染色体釉原蛋白基因;（3）构建转基因小鼠， 在成釉细胞中在釉原蛋白的控制下过表达LRAP 调节序列;和（4）用LRAP替换釉原蛋白蛋白 在老鼠牙釉质中。 在这些实验中，从基因上看， 将对改变的小鼠品系进行组织学比较， 蚀变，以及矿物晶体的质量和成分， 为了更好地了解有机基质在矿化中的作用， 过程

The amelogenins are extracellular matrix proteins, produced by ameloblasts during tooth enamel formation. These proteins are unique to enamel and are required for normal development of enamel mineral. The purpose of this application is to investigate regulation of expression of the X- chromosomal amelogenin gene, by analyzing the 3.5 KB fragment able to direct expression of a reporter gene to ameloblasts in transgenic mice, by sequence analysis and testing selected segments for activity using transgenic mice. We will also create in vivo a murine null mutation for the amelogenin gene, and express leucine rich amelogenin protein (RAP) in transgenic mouse enamel to determine whether overexpression will interfere with the normal function of amelogenin proteins. Mating of the knockout and LRAP mice will yield offspring which secrete LRAP as the only amelogenin protein in developing enamel. The specific aims are: (1) to characterize the regulatory sequences of the X-chromosomal amelogenin gene, using transgenic mice; (2) to construct a "knockout" mouse for the X-chromosomal amelogenin gene; (3) to construct a transgenic mouse that overexpresses LRAP in ameloblasts under control of the amelogenin regulatory sequence; and (4) to replace the amelogenin protein with LRAP in mouse tooth enamel. In these experiments, teeth from the 3 genetically altered mouse lines will be compared histologically for tissue alterations, and for quality and composition of mineral crystal, in order to better understand the role of the organic matrix in the mineralization process.