异甘草素缓解2型糖尿病小鼠能量代谢紊乱分子机制研究

Isoliquiritigenin alleviates energy metabolism imbalance in type 2 diabetic mice

异甘草素(isoliquiritigenin,ISL)是从甘草中分离得到的类黄酮化合物,具有良好的抗氧化、降血糖活性,本文旨在探究ISL缓解2型糖尿病(type 2 diabetes mellitus,T2DM)引起的能量代谢紊乱的分子机制。体内实验以8周龄C57BL/6J雄性小鼠为实验动物,采用高脂高糖饮食饲养合并腹腔注射链脲佐菌素的方法构建T2DM动物模型,实验操作和动物福利均遵循北京中医药大学实验动物伦理委员会规定;体外实验以人肝癌细胞HepG2为实验细胞系。采用酶联免疫吸附法(enzyme-linked immunosorbent assay,ELISA)和实时荧光定量PCR法(real-time quantitative polymerase chain reaction,RT-qPCR)检测线粒体功能相关靶点的蛋白和mRNA水平;采用流式细胞术检测线粒体活性氧(reactive oxygen species,ROS)和线粒体膜电位(mitochondrial membrane potential,MMP)水平;利用分子对接对ISL和部分靶点的相互作用进行验证。结果表明,ISL可显著抑制小鼠肝脏和HepG2细胞中线粒体呼吸链复合物I的活性,并提高解偶联蛋白2(uncoupling protein 2,UCP2)的水平;ISL还可显著降低ROS水平,并提高MMP水平。此外,ISL可通过激活过氧化物酶体增殖物激活受体γ辅激活子1α(proliferator-activatedreceptor gamma co-activator 1α,PGC-1α)促进线粒体生物发生;通过上调Parkin的转录和蛋白水平促进线粒体自噬;通过提高线粒体融合素2(mitofusin 2,MFN2)的转录和蛋白水平促进线粒体融合。综上,ISL可抑制T2DM小鼠肝脏线粒体过度氧化磷酸化,并通过促进线粒体生物发生、自噬和融合来缓解T2DM引起的能量代谢紊乱。

Isoliquiritigenin(ISL)is a flavonoid compound isolated from licorice.It possesses excellent antioxidant and anti-diabetic activities.This study aims to investigate the molecular mechanism underlying the alleviatory effect of ISL on energy metabolism imbalance caused by type 2 diabetes mellitus(T2DM).8-week-old male C57BL/6J mice were used in in vivo experiments.The high-fat-high-glucose diet combined with intraperitoneal injection of streptozotocin was applied to establish T2DM animal model.All animal experiments were performed in accordance with the Institutional Guidelines of Laboratory Animal Administration issued by the Committee of Ethics at Beijing University of Chinese Medicine.HepG2 cells were used in in vitro experiments.Enzyme-linked immunosorbent assay(ELISA)and real-time quantitative polymerase chain reaction(RT-qPCR)were used to examine the protein and mRNA levels of mitochondrial function-related targets.The levels of reactive oxygen species(ROS)and mitochondrial membrane potential(MMP)in HepG2 cells were measured by the flow cytometry.Additionally,the molecular docking of ISL and key target proteins was analyzed.It was found that ISL significantly inhibited the activity of mitochondrial respiratory chain complex I and increased the protein levels of uncoupling protein 2(UCP2)in the livers of mice and HepG2 cells.It also obviously decreased the ROS levels and increased the MMP levels in cultured HepG2 cells.In addition,ISL promoted mitochondrial biogenesis by activating proliferator-activated receptor gamma co-activator 1α(PGC-1α)and enhanced mitophagy by upregulating Parkin.It also improved mitochondrial fusion by increasing the mRNA and protein levels of mitofusin 2(MFN2).In conclusion,ISL alleviates energy metabolism imbalance caused by T2DM through suppression of excessive mitochondrial oxidative phosphorylation and promotion of mitochondrial biogenesis,mitophagy,and fusion.