Genetic Variations Related to Fluorosis Susceptibility

描述（由申请人提供）：牙釉质氟中毒是牙釉质发育的缺陷，在牙齿形成过程中暴露于过量的氟化物。关于氟化物影响牙釉质形成的机制，特别是氟化物对成釉细胞功能的影响，还有很多有待研究。对人类种群和小鼠品系的研究表明，个体对氟牙釉质中毒的易感性存在遗传因素。在这些研究中，我们将使用已知的氟化物敏感（A/J）或氟化物抗性（129P3/J）小鼠模型来确定对氟化物的这种可变反应负责的基因。这些研究将测试的总体假设是，牙釉质氟中毒是由在牙釉质发育过程中改变淀粉原蛋白和MMP-20相对水平的因素引起的。这一假设将通过以下具体目标进行检验。特异性目的1：确定候选基因在A/J和129P3/J小鼠品系中表达与氟化牙釉质严重程度的相关性。特异性目的2：确定氟对A/J和129P3/J小鼠品系JNK和cJun磷酸化的影响是否存在差异。特异性目的3：比较A/J和129P3/J小鼠品系中淀粉原蛋白基因的调控区域，并确定这种差异与氟斑牙的易感性/抗性之间的关系。我们将使用激光显微解剖显微镜从饮用氟化物的小鼠门牙中分离分泌和成熟阶段的成釉细胞。实时荧光定量PCR将用于定量淀粉原蛋白、MMP-20和其他候选基因的相对表达，以确定遗传多样性小鼠品系对氟化物的可变反应。通过测量两种小鼠模型中JNK/c-Jun合成和磷酸化的相对差异，将进一步研究MMP-20调节因子的遗传差异。将通过比较两种小鼠模型中的启动子序列来研究淀粉原蛋白基因的多态性。我们预计这些研究将导致确定候选基因，这将形成R01应用的基础，以进一步确定人类氟中毒的遗传易感性。

DESCRIPTION (provided by applicant): Enamel fluorosis is a defect in enamel development seen after exposure to excess fluoride during tooth formation. Much remains to be learned about the mechanisms by which fluoride affects enamel formation, and in particular the effect of fluoride on ameloblast function. Studies of human populations and mouse strains suggest that a genetic component to individual susceptibility to enamel fluorosis. In these studies we will use mouse models known to be either fluoride sensitive (A/J) or fluoride resistant (129P3/J) to identify genes responsible for this variable response to fluoride. The overall hypothesis that will be tested in these studies is that enamel fluorosis results from factors that alter the relative levels of amelogenin and MMP-20 during enamel development. This hypothesis will be tested by the following Specific Aims. Specific Aim 1: To determine the correlation between the expression of the candidate genes and severity of fluorosed enamel in the A/J and 129P3/J mouse strains. Specific Aim 2: To determine whether fluoride differentially effects phosphorylation of JNK and cJun, in A/J and 129P3/J mouse strains. Specific Aim 3: To compare the regulatory regions of the amelogenin gene in both A/J and 129P3/J mouse strains and determine how the differences relate to susceptibility/resistance to Dental fluorosis. We will use laser microdissection microscopy to separate secretory and maturation stage ameloblasts from incisors of mice given fluoride in drinking water. Real-time PCR will be used to quantitate relative expression of amelogenin, MMP-20, and other candidate genes to identify variable response to fluoride in the genetically diverse mouse strains. Genetic differences in regulators of MMP-20 will be further investigated by measuring relative differences in JNK/c-Jun synthesis and phosphorylation in the two mouse models. Polymorphisms in the amelogenin gene will be investigated by comparing promoter sequences in the two mouse models. We anticipate that these studies will result in the identification of candidate genes that will form the basis an R01 application to further determine genetic susceptibility to fluorosis in humans.