核受体FXR介导的石斛调节血脂机制的系统生物学研究

High serum lipid levels impact the public health for years. Although lots of synthetic medicines are developed to treat high serum lipids, the side effects are significant. A bright strategy is to screen new agents from known safe medicines, either synthetic chemicals or natural products. Traditional Chinese medicines (TCM) were applied in China for thousands of years. Although non-toxic are not guaranteed in TCM, Chinese people still summarized a series safe herbs in ancient medical books. Dendrobium is one of the important herb used for healthcare without significant side effect. The key lab of the ministry of education in Zunyi Medical College has studied Dendrobium for decades. Applicant in this lab found that Dendrobium lowers the serum lipid level significantly. Dendrobium also inhibited the gene expression of CYP7A1 in applicant’s preliminary studies. The binding of FXR on SHP promoter region was observed. As FXR is an important nuclear receptor regulating lipids, we suppose that Dendrobium regulate lipid homeostasis via FXR signaling pathways. In this proposal, we designed three parts of experiments to confirm our hypothesis. At first, we will check the effect of Dendrobium in wild type mice and FXR gene knockout mice. The role of FXR will be directly proved by this experiment. Second, the bile acids, and bile acids-related genes and proteins will be checked. This experiments will tell the mechanism that how Dendrobium regulates FXR. Finally, a high throughput transcriptome data will be analyzed to find out the significantly changed gene expressions at mRNA level. Moreover, a chromatin immunoprecipitation coupled with DNA sequencing (ChIP) will reveal the change of all FXR binding at genome-wide level. It was supposed that transcriptome and ChIP-Seq data together would figure out how Dendrobium regulate lipid homeostasis via FXR signaling pathway.

高血脂是影响健康的重要因素之一。目前的降脂药长期服用具有显著的毒副作用隐患。在安全药物中寻找降脂药物是研究的新型策略之一。石斛是《神农本草经》中记载的上品药物，养生无毒。本实验室长期研究证实石斛具有显著的降血脂活性。同时，前期研究也证明石斛可调控CYP7A1的基因表达，可增强FXR对其下游基因SHP启动子的结合。由于FXR是一类重要的脂质调控核受体，上述结果证明了石斛降血脂机制与FXR密切相关。本课题的目的在于：1）采用FXR基因敲除小鼠进一步明确FXR在石斛降血脂机制中的关键作用；2）通过对多种胆汁酸分子的高通量分析，对胆汁酸通路上46种关键因子的基因和蛋白水平的分析，研究石斛调控FXR的机制；3）通过转录组学、染色质免疫共沉淀结合DNA测序的基因组分析，研究石斛通过FXR调控脂质稳态的新机制。本研究将明确石斛降血脂作用机制及作用靶点，为降脂新药研发及石斛创新制剂研究明确方向。

高血脂是影响健康的重要因素之一。目前的降脂药长期服用具有显著的毒副作用隐患，寻找安全的降脂药物是研究热点之一。本研究通过高脂饮食诱导建立高脂血症动物模型，证明了金钗石斛调控脂质平衡的药理作用。利用UPLC-MS系统建立血清、胆汁、肝脏样本中胆汁酸的检测方法，进行胆汁酸组学的研究，揭示金钗石斛对FXR的调控。进行转录组学的研究，观察金钗石斛作用的宏观效果，快速发现受其调控的下游通路和基因，探索金钗石斛降血脂的系统生物学机制。建立肝脏样本蛋白组学检测方法，对提取纯化的蛋白进行全谱解析，并采用Western-blot方法检验相关重要蛋白表达的变化，结合胆汁酸组学、转录组学的结果，揭示金钗石斛调控核受体FXR的生物机制。建立FXR基因敲除动物高脂血症模型，验证了核受体FXR在金钗石斛降血脂机制中的重要性。针对FXR核受体，对肝脏样本的DNA进行检测及分析，捕捉FXR在基因组水平结合的位点，探索金钗石斛对FXR直接调控基因和通路的影响。本研究证明了金钗石斛具有调控脂质平衡的药理作用，揭示了金钗石斛通过核受体FXR介导产生降脂作用的机制，利用FXR基因敲除动物模型验证了核受体FXR在金钗石斛降血脂机制中的重要性。本研究为金钗石斛的开发提供了药理学依据。