铅通过ATF4调控RANKL和Sclerostin在成骨细胞内表达的机制研究

The individual lead overdose exposure in environment or in occupational workplace cause multi-system damage including the skeletal tissue, leads to bone disease such as osteoporosis. However, the underlie mechanism for lead induced osteoporosis is still unclear. Bone remodeling, which depends on the coupling between osteoblast and the other bone cells such as osteoclast, plays key role in pathogenesis of osteoporosis and needs RANKL and Sclerostin, both are secreted mainly by osteoblast lineage cells and essential for osteoblast-osteoclast coupling and osteoblast-osteoblast coupling respectively. With the findings that lead exposure induced RANKL and Sclerostin expression via ER stress transducer ATF4, in present project with the molecular biology strategies, the underlie mechanisms for lead induced RANKL and Sclerostin expression will be revealed in cellular and mouse model of lead exposure and in occupational population , which would enhance our knowledge about the toxicity of lead on bone and further provide the evidence for the prevention and treatment of lead induced osteoporosis in occupational population.

环境或职业因素所致的铅过量暴露造成机体的多系统损害，其中骨骼是最为常见的损伤器官之一，可引起骨质疏松等骨骼疾病，但其机制尚未完全明确。骨骼重塑依赖于成骨细胞和其它骨骼细胞间的信号耦联。骨骼重塑过程紊乱是骨质疏松等骨骼疾病的重要病理基础。RANKL和Sclerostin是由成骨细胞系细胞分泌的分别介导成骨细胞-破骨细胞、成骨细胞-成骨细胞信号耦联的必需分子。前期发现铅暴露通过内质网应激途径刺激成骨细胞中RANKL和Sclerostin表达，本项目在此基础上进一步采用铅暴露的成骨细胞模型、小鼠模型及职业性暴露人群样本结合分子细胞生物学实验手段探讨铅暴露通过内质网应激蛋白ATF4调节RANKL和Sclerostin表达的具体分子机制。本项目研究成果对于完善铅暴露骨骼毒性机制的认识以及职业人群铅暴露所致骨质疏松疾病的预防和治疗具有重要意义。

环境或职业因素所致的铅过量暴露造成机体的多系统损害，其中骨骼是最为常见的损伤器官之一，可引起骨质疏松等骨骼疾病，但其机制尚未完全明确。本项目发现成骨细胞铅暴露促进成骨细胞内参与调节成骨-破骨耦联的重要分子RANKL的表达，进一步研究发现铅暴露通过激活内质网应激信号PERK-eIF2-ATF4影响RANKL在成骨细胞内的表达，通过ATF4-siRNA、ISRIB、AMG’44等调节因子抑制PERK-eIF2-ATF4支路活性能显著降低铅暴露下RANKL的表达、分泌并抑制共培养体系中破骨细胞的生成。在铅暴露小鼠模型中，500ppm铅暴露能升高血清中RANKL表达水平并降低小鼠股骨的骨密度，而采用ISRIB抑制PERK-eIF2活性则能降低血清中RANKL表达同时缓解铅暴露对骨密度的影响。项目研究结果表明铅暴露通过激活PERK-eIF2-ATF4信号促进RANKL在成骨细胞内的表达并促进破骨细胞形成，导致成骨-破骨耦联失调，引起骨质疏松的发生。项目研究结果揭示了一种新的铅暴露致骨质疏松的分子机制，为开发有效的铅暴露人群骨骼健康防护策略提供了实验基础。.