Farnesoid X receptor (FXR) is a metabolic nuclear receptor, which protects liver from many endogenous and exogenous injuries. Metallothioneins (MTs) belong to a low-molecular-weight protein family involved in metal homeostasis and the regulation of hepatic oxidative stress. In the present study, we aimed to investigate the effect of FXR on hepatic MT1 expression and the underlying mechanism. C57BL/6 mice or primary cultured mouse hepatocytes were treated with the synthetic FXR ligand GW4064 or natural ligand CDCA. RNA-Sequencing (RNA-seq) analysis was performed to identify gene expression profile in the livers of mice treated with GW4064. Real-time PCR and Western blot were applied to determine the expression of MT1 and other FXR target genes in the livers of mice and primary hepatocytes treated with GW4064 and CDCA. Cellular and subcellular locations of MT1 in the livers of mice treated with GW4064 were examined using immunohistochemistry assay. FXR small interfering RNAs (siRNA) was transfected to silence FXR. Luciferase reporter and chromatin immunoprecipitation (ChIP) assays were utilized to confirm the regulation of MT1 gene promoter activity by FXR. RNA-seq analysis revealed that GW4064 treatment significantly induced MT1 expression in mouse liver. Consistently, MT1 expression in the hepatocytes of mouse livers and cultured hepatocytes was upregulated by GW4064 as well as CDCA. In addition, adenovirus-mediated overexpression of FXR markedly increased, while siRNA-mediated FXR silencing significantly suppressed MT1expression in cultured hepatocytes. Luciferase reporter and ChIP assays further confirmed that the MT1 gene was under the direct control of FXR. Collectively, our findings demonstrate that MT1 is a novel target gene of FXR and may contribute to antioxidative capacity of FXR in liver diseases.

法尼醇X受体（FXR）是一种代谢核受体，可以保护肝脏免受许多内源性和外源性伤害。金属硫蛋白（MTs）属于低分子量蛋白家族，参与金属稳态和肝氧化应激的调节。在本研究中，我们旨在研究FXR对肝MT1表达的影响及其潜在机制。用合成的FXR配体GW4064或天然配体CDCA处理C57BL / 6小鼠或原代培养的小鼠肝细胞。进行RNA测序（RNA-seq）分析以鉴定用GW4064处理的小鼠肝脏中的基因表达谱。应用实时荧光定量PCR和Western印迹法测定MT1和其他FXR靶基因在用GW4064和CDCA处理的小鼠肝脏和原代肝细胞中的表达。使用免疫组织化学测定法检查了用GW4064处理的小鼠肝脏中MT1的细胞和亚细胞位置。FXR小干扰RNA（siRNA）被转染以沉默FXR。萤光素酶报告基因和染色质免疫沉淀（ChIP）分析用于确认FXR对MT1基因启动子活性的调节。RNA-seq分析显示，GW4064处理可明显诱导小鼠肝脏MT1表达。一致地，GW4064和CDCA上调了小鼠肝脏和培养的肝细胞中MT1的表达。此外，腺病毒介导的FXR过表达显着增加，而siRNA介导的FXR沉默则显着抑制了培养的肝细胞中MT1的表达。萤光素酶报告基因和ChIP分析进一步证实了MT1基因在FXR的直接控制之下。总的来说，我们的发现表明MT1是FXR的新型靶基因，可能有助于FXR在肝脏疾病中的抗氧化能力。