苯并芘通过AhR影响肝脏脂质合成的分子机制研究

目的研究苯并芘(BaP)对肝脏脂质合成的影响及其分子机制。方法用低、中和高剂量的BaP给小鼠灌胃,检测谷草转氨酶(AST)、谷丙转氨酶(ALT)的水平,油红O染色法检测脂质含量,qPCR法和Western blot法检测脂肪生成及转运相关基因过氧化物酶体增殖剂激活受体γ(PPARγ)、硬脂酰辅酶A去饱和酶1(SCD1)和脂肪酸转运酶(CD36)的mRNA和蛋白表达。在HepG2细胞中加多环芳经受体(AhR)抑制剂CH223191观察BaP对以上各指标的影响。结果与溶剂对照组相比,低、中和高剂量组的BaP可以显著升高小鼠肝脏中ALT水平(P<0.05,P<0.01,P<0.001),中、高剂量组的BaP可以升高AST水平(P<0.05,P<0.001);中、高剂量组的BaP能够显著增加小鼠肝脏脂质聚集(P<0.01,P<0.001);三种剂量的BaP均可使HepG2细胞中脂质聚集增加(P<0.01,P<0.001);三种剂量的Ba P均可使小鼠肝脏的PPARγ、SCD1和CD36的蛋白表达和CD36的m RNA表达升高(P<0.05,P<0.01,P<0.001);中、高剂量组的BaP均可使小鼠肝脏的PPARγ、SCD1的mRNA表达升高(P<0.01,P<0.001)。中、高剂量的BaP均可使HepG2细胞中的PPARγ、SCD1和CD36的mRNA和蛋白表达增加(P<0.05,P<0.01,P<0.001)。加AhR抑制剂后,脂质含量明显降低,并可显著降低PPARγ、SCD1和CD36的m RNA和蛋白表达(P<0.05,P<0.01)。结论BaP可能通过AhR促进肝脏组织中脂肪生成及转运相关基因的表达进而促进肝脏脂质合成。

mi R-192-5p regulates lipid synthesis in non-alcoholic fatty liver disease through SCD-1

AIM To evaluate the levels of mi R-192-5 p in non-alcoholic fatty liver disease(NAFLD) models and demonstrate the role of mi R-192-5 p in lipid accumulation. METHODS Thirty Sprague Dawley rats were randomly divided into three groups, which were given a standard diet, a high-fat diet(HFD), and an HFD with injection of liraglutide. At the end of 16 weeks, hepatic mi R-192-5 p and stearoyl-Co A desaturase 1(SCD-1) levels were measured. Mi R-192-5 p mimic and inhibitor and SCD-1 si RNA were transfected into Huh7 cells exposed to palmitic acid(PA). Lipid accumulation was evaluated by oil red O staining and triglyceride assays. Direct interaction was validated by dual-luciferase reporter gene assays.RESULTS The HFD rats showed a 0.46-fold decrease and a 3.5-fold increase in hepatic mi R-192-5 p and SCD-1 protein levels compared with controls, respectively, which could be reversed after disease remission by liraglutide injection(P < 0.01). The Huh7 cells exposed to PA also showed down-regulation and up-regulation of mi R-192-5 p and SCD-1 protein levels, respectively(P < 0.01). Transfection with mi R-192-5 p mimic and inhibitor in Huh7 cells induced dramatic repression and promotion of SCD-1 protein levels, respectively(P < 0.01). Luciferase activity was suppressed and enhanced by mi R-192-5 p mimic and inhibitor, respectively, in wild-type SCD-1(P < 0.01) but not in mutant SCD-1. Mi R-192-5 p overexpression reduced lipid accumulation significantly in PA-treated Huh7 cells, and SCD-1 si RNA transfection abrogated the lipid deposition aggravated by mi R-192-5 p inhibitor(P < 0.01).CONCLUSION This study demonstrates that mi R-192-5 p has a negative regulatory role in lipid synthesis, which is mediated through its direct regulation of SCD-1.

延边黄牛SREBP1和SCD1基因表达的发育性变化及与肌间脂肪含量的关联分析

文章旨在研究延边黄牛不同生长阶段固醇调节元件结合蛋白1（Sterol regulatory ele-ment binding factor 1,SREBP1）和硬脂酰辅酶A去饱和酶1（Stearoyl Co A desaturease 1,SCD1）基因表达的发育性变化与IMF含量的相关性以及这两个基因表达水平的关联性。试验选取12月龄的延边黄牛公牛（去势）8头,利用微量微创活体采样枪（韩国忠北大学提供）,分别在12月龄,16月龄,20月龄,采集肌肉组织（臀肌）;利用实时荧光定量PCR方法分析SREBP1和SCD1基因在延边黄牛不同生长阶段肌肉组织中的m RNA发育性变化。结果表明：1延边黄牛SREBP1基因相对表达水平在12、16、20月龄具有极其显著差异（P〈0.01）,其中20月龄时SREBP1基因表达量相对最高;SCD1基因相对表达水平在12、16、20月龄具有显著差异（P〈0.05）,其中20月龄时SCD1基因表达量相对最高。2肌肉组织中SREBP1基因的表达量在12~20月龄期间与IMF含量具有正向相关性,相关系数为0.910（P〈0.05）;SCD1基因的表达量在12~20月龄期间与IMF含量具有正向相关性,相关系数为0.934（P〈0.05）。结果表明,SREBP1和SCD1基因在延边黄牛不同生长阶段存在显著或极显著差异,SREBP1和SCD1基因的协同表达对延边黄牛不同生长阶段肌内脂肪的沉积有一定的正向调控作用。