miRNA的表达在职业镉暴露致肾功能损伤中的作用

Some studies reported the changes in expression of miRNA have been associated with diseases caused by heavy metals. Epidemiology investigations have associated Cd exposure with the increasing risks of renal dysfunction. The mechanisms are largely undetermined. The workers exposed to different levels of Cd were selected as subjects. MiRNA microarray and quantitative real-time PCR will be used to measure and verify the differential expression of miRNA in blood leukocyte RNA．The research is to explore the relationship between nephrotoxicity caused by Cd and the differential expression of miRNA, and look for the earlier effect biomarkers that are able to predict the renal injury induced by occupational cadmium exposure. Through the establishment of rat model of renal injury caused by cadmium exposure, for the purpose of exploring the impact that different periods, different doses of cadmium exposure has on rat kidney miRNA expression, apoptosis, oxidative stress. Provide a basis to investigate cadmium exposure due to epigenetic mechanisms of renal injury. Using the gene transfection technology enables the expression of miRNA selected by epidemiology investigation and animal tests to be high or low in HEK-293,which evaluate the effects on the relative indexes of HEK-293 cells that cadmium exposure has, and reveal the miRNA targets point of cadmium nephrotoxicity. In this study, studying from molecular and cellular level to the population studies, we want to explore the role of miRNA expression changes playing on cadmium renal toxicity, and to find the effective biological monitoring indicators and the basis for the elucidation of the mechanism of miRNA .

在重金属暴露所致疾病发生中miRNA表达的改变发挥着重要的调节作用。有关miRNA在镉肾毒性中的作用和机制还不清楚。本研究拟采用miRNA芯片技术和RT-PCR结合筛查职业镉暴露与非暴露人群外周血差异表达的miRNA，探讨镉肾毒性与miRNA 差异表达的关系，寻找能够预测镉暴露所致肾功能损伤的早期效应标志物。建立镉暴露所致肾功能损伤的大鼠模型，探讨不同时期、不同剂量镉暴露对大鼠肾脏组织miRNA的表达、细胞凋亡、氧化应激反应等的影响，为探讨镉暴露所致肾功能损伤的表观遗传机制提供依据。利用基因转染技术，使与镉肾毒性密切相关的miRNA在人胚肾细胞（HEK-293细胞）不表达或高表达的情况下，评价镉暴露对HEK-293细胞相关指标的影响，揭示miRNA在镉肾毒性中的作用靶点。本研究从分子细胞水平到人群研究，探寻miRNA表达与镉肾毒性的关系，为寻找有效的生物监测指标和阐明作用机制提供依据。

镉污染是近年来在我国频发的污染事件，严重危害着人类的健康。目前关于镉对人体健康效应的机制尚未研究清楚，也无有效的排除方法，因此寻找预测镉暴露和疾病发生早期的分子标志物具有十分重要的意义。本研究采用miRNA芯片技术，筛选并验证了镉暴露和非镉暴露所致外周血差异表达的miRNA，探讨其与镉暴露所致肾功能损伤的关系。获得以下的研究结果：（1）暴露于2.0mg/kg•bw镉组大鼠肾脏已出现肾功能改变，并显示机体的氧化与抗氧化动态平衡被破坏; （2）镉暴露所致肾功能损伤大鼠肾脏组织中miRNA-21、miR-29b、miR-21c表达上调；且经miRNA生物信息学分析结果显示，miRNA的表达改变可能参与MAPK信号通路、TGF-β等信号通路的调控。（3）采用miRNA转染技术，对人胚肾细胞（HEK细胞）经miRNA mimic和miRNA inhibitor转染后，显示细胞凋亡率增加；氧化应激指标发生改变，其中经miRNA-21 mimic转染后，细胞中MDA和ROS含量增加，SOD和GSH-PX活性降低，而经inhibitor转染后，细胞MDA和ROS含量降低，SOD和GSH-PX活性增加；提示miRNA能够影响细胞的氧化应激状态。（4）细胞经miRNA转染后染镉，显示与对照相比，mimic使细胞凋亡率增加，MDA和ROS含量增加，SOD和GSH-PX活性降低，而inhibitor转染后导致细胞凋亡率降低，MDA和ROS含量降低，SOD和GSH-PX活性增加，提示miRNA在镉所致毒效应中发挥一定的调控作用。（5）进一步以人群小样本筛选镉暴露所致肾功能损伤miRNA差异表达情况，并经Real-time PCR验证，结果显示不同镉暴露水平导致miRNA的差异表达，其中miR-21和miR-29表达上调。由此我们发现miRNA参与镉暴露所致肾功能损伤的过程，并发挥着一定的作用，可能会作为镉暴露致机体健康效应的早期生物标志。