生（干）姜及其主要活性成分改善非酒精性脂肪肝过程中对肝ChREBP的分子调控

Fatty liver is the hallmark of nonalcoholic fatty liver disease, which has become an important public health problem due to its high prevalence, potential progression to severe liver disease, and association with the metabolic syndrome, diabetes and cardiometabolic abnormalities. Fatty liver belongs to "Phlegm-dampness" due to dysfunction of spleen and stomach in TCM. Ginger is one of the most commonly used spices and medicinal plants around the world. Ginger is attributed to spleen and stomach channels, functions as a spleen-stomach-regulating herb, and widely used in the formulas for Phlegm-dampness syndrome in TCM. It has been well demonstrated that ginger improves dietary-induced fatty liver in rodents. However, the molecular mechanisms underlying the anti-steatotic effect of ginger are still unknown. Recently, Our research team has found that ginger improves fructose overconsumption-induced fatty liver via the hepatic pathway of ChREBP, an attractive molecular target for lipid-lowering therapies in obesity and diabetes. Based on this important finding, we in the proposed project will investigate how ginger and its prominent active components regulate hepatic ChREBP O-GlcNAcylation, phosphorylation and their 'Yin-Yang' relationship at "nuclear translocation" and "DNA banding/transcription activities" level using the well-accepted rat model of fructose-induced fatty liver and the specific HepG2 cell model of fructose-activated ChREBP. The findings of this project will not only supply with molecular pharmacological basis for developing new potent medicine for fatty liver from ginger, but also provide new insight into the spleen and stomach-regulating property of ginger in the prevention and treatment of Phlegm-dampness syndrome. Thus, this project has novelty and significance.

非酒精性脂肪肝是非酒精性脂肪肝病的标志，可发展成严重的肝病，近年来发病率猛增，严重危害国民健康。脂肪肝属痰湿范畴，与脾胃功能失调密切相关。生（干）姜为最常用的中药和调味料之一，主要取其调理脾胃、治疗痰湿的功效，其防治脂肪肝的疗效已为现代研究所证实。但其作用机制尚不清楚。我们最新研究结果证明，调节糖脂代谢的关键因子――碳水化合物反应元件结合蛋白(ChREBP)是姜提取物改善脂肪肝的重要靶标。基于此重要发现，本项目采用模拟人类非酒精性脂肪肝的细胞和动物模型，通过观察在"核转位"和"DNA结合／转录活性的激活"两个水平上对ChREBP磷酸化、糖基化，及二者的"阴阳"关系平衡的调节作用，从蛋白质修饰这一新视点，进一步探讨姜提取物及其主要活性成分对肝ChREBP的分子调控。此项目的顺利实施将为从生（干）姜中开发新型防治脂肪肝的高效低毒药物提供分子药理学依据，并有助于揭示其调理脾胃、防治痰湿证的本质。

非酒精性脂肪肝是非酒精性脂肪肝病的标志，可发展成严重的肝病，近年来发病率猛增，严重危害国民健康。脂肪肝属痰湿范畴，与脾胃功能失调密切相关。生（干）姜为最常用的中药和调味料之一，主要取其调理脾胃、治疗痰湿的功效，其防治脂肪肝的疗效已为现代研究所证实。但其作用机制尚不清楚。本课题在既往研究的基础上，应用高果糖致大鼠脂肪肝模型、自然衰老相关的大鼠脂肪肝模型和db/db小鼠等动物模型，以及油酸致HepG2细胞甘油三酯沉积细胞模型，主要围绕本课题的研究目标：姜提取物及其主要活性成分6-姜辣素和6-姜烯酚改善脂肪肝中对肝碳水化合物反应元件结合蛋白 (ChREBP) 磷酸化和糖基化的影响进行研究。我们研究证明，ChREBP是姜提取物改善脂肪肝的重要靶标；姜提取物 (50mg/kg) 可选择性激活PKA，使ChREBP发生磷酸化而停留在胞浆中，逆转果糖引起的肝细胞ChREBP核转位，从而改善脂肪肝。出乎预料的是，姜提取物及其主要活性成分6-姜辣素和6-姜烯酚改善脂肪肝中对肝OGT、OGA没有影响、ChREBP的糖基化变化不明显，但它们均能逆转脂肪肝DGAT2的过表达，这是一个值得注意的新发现；另外，6-姜辣素 (0.2mg/kg) 可降低老年大鼠肝ChREBPmRNA的水平，但是对其在胞核、胞浆蛋白的表达水平没有影响，其下游LPK也未发生变化；6-姜辣素能逆转老年大鼠肝脏PPARα和CPT-1α的降低从而增加脂肪酸氧化，并且升高了TCA中Cs的表达水平，增加了柠檬酸盐及ATP含量；降低了ROS产物，升高了SDH、NOX的含量，从而增强了肝脏线粒体功能；6-姜烯酚也能降低db/db小鼠肝脏PKC1mRNA的过表达。再者，在连续多批的果糖致脂肪肝动物实验中，我们发现一个很有意义的现象，SCD1基因可以不依赖上游转录因子 (ChREBP和SREBP1c) 的调控发挥作用，在果糖所致脂肪肝中扮演非常重要的角色。这些研究结果，一方面为脂肪肝的病理生理机制提供了新认识；同时也为生(干)姜防治脂肪肝提供了新证据，丰富了中医药调理脾胃以防痰湿从而改善脂肪肝的理论内涵。