基于Tyk2/STAT3信号通路介导的棕色脂肪细胞分化及能量代谢探讨根皮苷抑制肥胖的机制研究

Obesity occurs when caloric intake exceeds energy expenditure with excess nutrients stored as fat. Brown adipose tissue (BAT) is responsible for energy expenditure in the form of thermogenesis. Many researches have indicated that BAT is a potential target for the treatment of obesity which is effective in reducing the excessive accumulation of body energy. Tyk2/STAT3 signaling pathway plays an essential role in regulating BAT differentiation and obesity. Our previous studies found that phlorizin exerted antiobesity effect in high-fat-diet induced obese animals. It decreased adipose mass and body weight and with no impact on appetite. The mechanisms underlying these effects are associated with the promotion of the energy metabolism, improvement of the p-STAT3 protein expression in adipose tissue significantly. So we hypothesize that the phlorizin promotes the energy metabolism of obese subjects by mediating Tyk2/STAT3 signaling pathway and inducing the differentiation of BAT. In this study the mechanism of phlorizin's promotion on energy metabolism through regulating Tyk2/STAT3 signaling pathway, is to be evaluated at the levels of general, cell and molecular. Animal models are including Tyk2-/- and Tyk2-/- mice, high fat diet induced obese mouse. Energy metabolism improvement inducing by phlorizin will be detected on these animals with the application of infrared thermal imaging technology. Cell lines are involving original cells isolated from newborn Tyk2+/+ and Tyk2-/- mice, C57BL/6j mice and the techniques of siRNA. Light microscope and electron microscope will be also used to study the differentiation of BAT accompanying with western blot and RT-PCR to determine the expression of Tyk2/STAT3 signaling pathway in BAT. The outcomes of this study will throw lights on the knowledge of regulative effect of phlorizin on BAT and prompt the development of indigenous innovative drugs.

棕色脂肪是耗能型脂肪组织，能够有效减少机体能量的过度堆积；促进棕色脂肪细胞分化是研发治疗肥胖药物的热门靶点。Tyk2/STAT3信号通路是调节棕色脂肪细胞分化的关键途径。我们前期研究发现根皮苷显著抑制肥胖大鼠白色脂肪的堆积，促进机体能量代谢及脂肪组织p-STAT3蛋白的表达。基于此，本项目提出"根皮苷通过调节Tyk2/STAT3信号通路活性，促进棕色脂肪细胞分化及能量代谢，从而抑制肥胖"的假说。本研究将以棕色脂肪细胞分化为突破点，采用红外热成像、电镜等技术跟踪根皮苷干预下，饮食诱导的肥胖小鼠、Tyk2-/-小鼠棕色脂肪组织的分化及能量代谢特点；体外采用正常棕色脂肪细胞及Tyk2-/-棕色脂肪细胞，结合siRNA干扰技术、阻断剂等进一步验证根皮苷对Tyk2/STAT3信号通路、细胞分化的影响，探讨Tyk2/STAT3信号通路介导的棕色脂肪细胞分化及能量代谢在根皮苷抑制肥胖中的作用。

棕色脂肪是耗能型脂肪组织，能够有效减少机体能量的过度堆积;促进棕色脂肪细胞分化 是研发治疗肥胖药物的热门靶点。Tyk2/STAT3信号通路是调节棕色脂肪细胞分化的关键途径。我们前期研究发现根皮苷显著抑制肥胖大鼠白色脂肪的堆积，促进机体能量代谢及脂肪组织p-STAT3蛋白的表达。基于此，本项目提出"根皮苷通过调节Tyk2/STAT3信号通路活性，促进棕色脂肪细胞分化及能量代谢，从而抑制肥胖"的假说。本研究将以棕色脂肪细胞分化为突破点，采用红外热成像、电镜等技术跟踪根皮苷干预下，饮食诱导的肥胖小鼠 、Tyk2-/-小鼠棕色脂肪组织的分化及能量代谢特点;体外采用正常棕色脂肪细胞及Tyk2- /-棕色脂肪细胞，结合siRNA干扰技术、阻断剂等进一步验证根皮苷对Tyk2/STAT3信号通路、细胞分化的影响，探讨Tyk2/STAT3信号通路介导的棕色脂肪细胞分化及能量代谢在根皮苷抑制肥胖中的作用。研究结果显示：根皮苷通过改善棕色脂肪细胞线粒体的形态功能从而促进产热；但是根皮苷未能诱导白色脂肪棕色化；根皮苷可促进棕色脂肪组织Tyk2/STAT3信号通路的表达，但是Tyk2/STAT3信号通路并非根皮苷的靶通路。