Genetic Variations Related to Fluorosis Susceptibility

描述（由申请人提供）：牙釉质氟中毒是牙齿形成过程中暴露于过量氟化物后出现的牙釉质发育缺陷。关于氟化物影响釉质形成的机制，特别是氟化物对成釉细胞功能的影响，仍有许多问题有待研究。对人群和小鼠品系的研究表明，个体对氟牙釉质症的易感性与遗传因素有关。在这些研究中，我们将使用已知的氟敏感（A/J）或氟抗性（129 P3/J）小鼠模型来鉴定负责这种对氟的可变反应的基因。在这些研究中将检验的总体假设是，釉质氟中毒是由在釉质发育过程中改变釉原蛋白和MMP-20的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。具体目标1：目的探讨A/J和129 P3/J小鼠氟斑牙釉质病变程度与候选基因表达的相关性。具体目标2：确定氟化物是否对A/J和129 P3/J小鼠品系中JNK和cJun的磷酸化产生差异影响。具体目标3：比较A/J和129 P3/J小鼠釉原蛋白基因调控区的差异，并确定其与氟斑牙易感性/抗性的关系。我们将使用激光显微切割显微镜分离分泌和成熟阶段的成釉细胞从小鼠切牙氟饮用水。实时PCR将被用来定量釉原蛋白，MMP-20，和其他候选基因的相对表达，以确定在遗传多样性的小鼠品系的可变响应氟。MMP-20调节因子的遗传差异将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来进一步研究。通过比较两种小鼠模型的启动子序列，研究釉原蛋白基因的多态性。我们预计，这些研究将导致候选基因的识别，将形成R 01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.