Sun Chao, Liu Wei, Lu Zhiqiang, Li Yan, Liu Shengnan, Tang Zhili, Yan Ying, Li Zhiyang, Feng Hua, Zhang Duo, Liu Yun, Fang Zhong-Ze, Jiang Changtao, Ding Qiurong, Jiang Jingjing, Ying Hao
CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai 200032, China.
Theranostics. 2021 Feb 25;11(9):4363-4380. doi: 10.7150/thno.53624. eCollection 2021.
An improved understanding of thyroid hormone (TH) action on cholesterol metabolism will facilitate the identification of novel therapeutic targets for hypercholesterolemia. TH-regulated microRNAs (miRNAs) have been implicated in TH-controlled biological processes; however, whether and how TH-regulated miRNAs mediate the cholesterol-lowering effect of TH remains unclear. Our aim was to identify TH-regulated microRNAs that have cholesterol-lowering effects and explore the underlying mechanism. Microarray and RNA-seq were performed to identify TH-regulated microRNAs and the genes regulated by mmu-miR-378-3p (miR-378) in the liver of mice, respectively. Recombinant adenoviruses encoding miR-378, , and shRNA for , antagomiR-378, liver-specific miR-378 transgenic mice, and miR-378 knockout mice were employed to investigate the roles of hepatic miR-378 and MAFG in cholesterol and bile acid homeostasis. The levels of bile salt species were determined by using UFLC-Triple-time of flight/MS. Here, we show that hepatic miR-378 is positively regulated by TH. Transient overexpression of miR-378 in the liver of mice reduces serum cholesterol levels, accompanied with an increase in the expression of key enzymes in primary bile acid synthetic pathways and corresponding increases in biliary and fecal bile acid levels. Consistently, liver-specific miR-378 transgenic mice with moderate overexpression of hepatic miR-378 display decreased serum cholesterol levels and resistance to diet-induced hypercholesterolemia, while mice lacking miR-378 exhibit defects in bile acid and cholesterol homeostasis. Mechanistically, hepatic miR-378 regulates the expression of key enzymes in both classic and alternative bile acid synthetic pathways through MAFG, a transcriptional repressor, thereby modulating bile acid and cholesterol metabolism. TH-responsive hepatic miR-378 is capable of modulating serum cholesterol levels by regulating both the classic and alternative BA synthetic pathways. Our study not only identifies a previously undescribed role of hepatic miR-378 but also provides new cholesterol-lowering approaches.
对甲状腺激素（TH）作用于胆固醇代谢的深入了解将有助于确定高胆固醇血症的新治疗靶点。TH调控的微小RNA（miRNA）已被证明参与TH控制的生物学过程；然而，TH调控的miRNA是否以及如何介导TH的降胆固醇作用仍不清楚。我们的目的是鉴定具有降胆固醇作用的TH调控的微小RNA，并探索其潜在机制。分别进行微阵列和RNA测序以鉴定TH调控的微小RNA以及小鼠肝脏中受mmu-miR-378-3p（miR-378）调控的基因。使用编码miR-378、针对MAFG的短发夹RNA（shRNA）、抗miR-378、肝脏特异性miR-378转基因小鼠和miR-378基因敲除小鼠的重组腺病毒来研究肝脏miR-378和MAFG在胆固醇和胆汁酸稳态中的作用。使用超高效液相色谱-三重四极杆飞行时间质谱法测定胆汁盐种类的水平。在此，我们表明肝脏miR-378受TH正向调控。在小鼠肝脏中瞬时过表达miR-378可降低血清胆固醇水平，同时初级胆汁酸合成途径中关键酶的表达增加，胆汁和粪便中胆汁酸水平相应升高。同样，肝脏miR-378适度过表达的肝脏特异性miR-378转基因小鼠血清胆固醇水平降低，对饮食诱导的高胆固醇血症具有抗性，而缺乏miR-378的小鼠在胆汁酸和胆固醇稳态方面存在缺陷。机制上，肝脏miR-378通过转录抑制因子MAFG调节经典和替代胆汁酸合成途径中关键酶的表达，从而调节胆汁酸和胆固醇代谢。TH反应性肝脏miR-378能够通过调节经典和替代胆汁酸合成途径来调节血清胆固醇水平。我们的研究不仅确定了肝脏miR-378以前未被描述的作用，还提供了新的降胆固醇方法。
