弓状核神经元中Argonaute2蛋白调控能量代谢和肥胖发展的作用机制

Obesity is related to energy imbalance between intake and expenditure. The neurons in the arcuate nuclei of the hypothalamus play key role in the energy homeostasis. As a core element of RNA-induced silencing complex, Ago2 has been involved in many physiological and pathological processes and is strongly linked to the obesity. In our previous study, mice with elimination of Ago2 in Vglut2 excitatory neurons have decreased body weight, improved overall insulin sensitivity and increased energy expenditure. While, deletion of Ago2 in Vgat inhibitory neurons has no effect on the energy homeostasis. Furthermore, mice with conditional deletion of Ago2 in POMC neurons exhibit increased insulin sensitivity and energy expenditure, and decreased body weight. Based on those results, we hypothesized that Ago2 expressing in the hypothalamic Arc neurons play an important role in the energy balance and lipid metabolism. In present project, we will use several genetically engineered mice and different advanced bio-techniques, such as genetic engineering, TSE Phenomaster metabolic cages, immunofluorescence, immunoprecipitation, electron microscope and electrophysiology. We will investigate the function of Ago2 in the POMC and AgRP neurons. This project will explore the functional mechanisms of Ago2 on the obesity and further provide basic research data for the potential clinic treatment of obesity.

肥胖发生与能量稳态的失衡有关，下丘脑弓状核神经元是调节能量平衡的关键部位。Ago2作为RISC的核心元件，参与机体重要的生理及病理过程,与肥胖症的发生密切相关。我们前期研究显示，在小鼠Vglut2兴奋性神经元中特异敲除Ago2基因，小鼠变瘦，胰岛素敏感性提高，能量消耗增加，提高机体产热；在Vgat抑制性神经元中特异敲除Ago2基因并不影响体能代谢；进一步在下丘脑POMC神经元中特异敲除Ago2基因，提高小鼠对胰岛素的敏感性，增加机体能耗，起到减轻体重的效果。由此，我们推测Ago2在下丘脑弓状核神经元中对于能量平衡和脂质代谢具有重要功能。本项目将利用多种基因工程小鼠，结合基因重组、TSE小鼠能量代谢监测、免疫荧光染色、免疫沉淀、扫描电镜、电生理等方法，研究POMC和AgRP神经元中Ago2的功能，揭示Ago2对于肥胖及代谢疾病的影响和作用机制，将为进一步发现肥胖的病因与治疗提供重要理论基础。

肥胖的发生与能量稳态的失衡有关，下丘脑弓状核神经元是调节机体能量平衡的关键部位。本课题通过基因重组技术、TSE小鼠能量代谢监测分析、免疫沉淀、qRT-PCR、Western blot以及细胞代谢分析等技术，从机体系统性差异和内源性基因调控两个方面研究下丘脑神经元中Ago2的功能。通过我们的研究发现：1）Ago2在POMC神经元中能够提高机体敏感性，调节机体能耗；2）特异性敲除POMC神经元中的Ago2基因能够提高机体脂肪褐色化；3）特异性敲除在AgRP神经元中的Ago2并不影响机体代谢平衡；4）免疫沉淀证实，Ago2能与多种不同的miRNAs结合，以此调控神经元的形态结构和生理活性；5）Seahorse XF24细胞代谢呼吸动态分析表明，敲除神经元中的Ago2基因，会导致线粒体功能紊乱，明显增加细胞的能量代谢。综合以上结果，证实Ago2在下丘脑中主要通过对POMC神经元的调控来参与到机体的代谢平衡过程，揭示Ago2对于肥胖及其代谢疾病的影响和作用机制，将为进一步发现肥胖的病因与治疗提供重要理论基础。