CaN-NFATc1通路与小鼠氟骨症发生的关系及其分子作用机理研究

Endemic fluorosis has been found and is popular differently in over 50 countries and areas in the world. China is one of the most popular areas of endemic fluorosis in where over 100 million people are threatened by fluorosis. There are 28.823 million people with dental fluorosis and 5.637 million people with skeletal fluorosis. However the pathogenesis of fluorosis is still unclear and this disease can be prevented rather than be cured. Recent research showed that calcineurin(CaN)-nuclear factor of active T cells c1(NFATc1) pathway plays an important role in bone metabolism. The applicant's team firstly found that fluoride reduced the bone resorption activity of osteoclast through the inhibition of NFATc1 and its downstream genes expression. So we speculate that NFATc1 may be associated with the pathogenesis of skeletal fluorosis. At present, there is no report about the relationship between the gene function and molecular mechanism of CaN-NFATc1 pathway and the pathogenesis of skeletal fluorosis. Based on previous work, techniques such as animal model of fluorosis and stem cell technique will be used in this study in order to investigate the relationship between CaN-NFATc1 pathway and skeletal fluorosis. Secondly, NFATc1 recombination gene and its inhibitor CsA will be apply to study gene function and molecular mechanism of CaN-NFATc1 pathway on osteoblast and osteoclast treated with fluoride. This study has an important significance which not only further reveal the molecular mechanism of pathogenesis of skeletal fluorosis but also discover the effective molecular target against fluoride toxic effect.

地方性氟中毒在全世界50多个国家和地区有不同程度流行。我国为地氟病流行严重的地区之一，受威胁人口1亿多人，现有氟斑牙患者2882.3万人，氟骨症病人563.7万人。目前由于氟中毒的发病机制仍不清楚，导致该病可防而不可治。近年研究表明CaN-NFATc1在骨代谢中具有重要作用，申请人所在课题组新近研究发现氟能够显著抑制NFATc1及其下游功能基因的表达而减弱破骨细胞骨吸收活性，我们推测CaN-NFATc1与氟骨症发病有一定联系，但目前尚无人对CaN-NFATc1通路与氟骨症发生的关系及其分子机制进行研究。本研究拟在前期工作的基础上，利用氟中毒动物模型、干细胞定向分化、基因重组等技术，探讨CaN-NFATc1通路与氟骨症之间的关系以及该通路在氟对成（或破）骨细胞毒性作用中的基因功能及分子机制。本研究对进一步揭示氟骨症发病的分子作用机理，寻找有效拮抗氟毒性作用的分子靶点具有重要意义。

氟骨症是一种病因明确的骨代谢疾病，但由于其发病机制不清，导致该病可防而不可治。研究表明，地氟病病区居民血清钙水平与氟骨症发生呈负相关，低钙能加强氟对实验动物的骨骼毒性作用，提示钙在氟骨症发生中具有重要作用。目前，钙参与氟骨症发生的分子机制仍不清楚。新近研究发现，受钙离子调节的CaN-NFATc1 信号通路与骨细胞生长发育密切相关。本研究在动物活体和细胞水平，观察了氟中毒小鼠骨组织病理形态改变和骨代谢标志物表达的变化，并分析了不同浓度氟暴露下小鼠骨组织中CaN和NFATc1及其上游调节因素钙、钙调蛋白、AP-1等的蛋白表达变化，较系统地研究了CaN-NFATc1 信号通路与氟骨症的关系。.本项目的主要结果：.1.小鼠氟斑牙检出率和严重程度随着氟暴露浓度的升高而增加。.2.氟能导致骨细胞微观结构受损和骨病理形态出现异常改变，主要表现为骨小梁增粗、骨质融合等骨量增多样改变。.3.氟中毒小鼠骨组织中破骨细胞形成数量增多，但与氟暴露无剂量反应关系。.4.过量氟中毒小鼠骨组织中骨形成和骨吸收标志物表达均有升高，BGP是反映氟暴露水平较为敏感的骨形成标志物，TRAP和MMP-9是反映氟暴露水平较为敏感的骨吸收标志物，且TRAP更加敏感。.5.氟对小鼠骨组织中钙和钙调蛋白含量无影响，钙参与氟骨症的机制还有待进一步研究。.6.氟中毒小鼠骨组织中破骨细胞形成增多的分子机制可能和骨组织中c-fos、c-jun、CaN和NFATc1蛋白高表达有关，CaN-NFATc1信号通路参与氟骨症发生的具体分子机制仍需深入研究。