低氧训练通过HIF-1α-miR-122-5p-SREBP-1c调节肥胖大鼠肝脏脂代谢的机制研究

The Mechanism of Hypoxic Training Regulating Lipid Metabolism by HIF-1α-miR-122-5p-SREBP-1c in Obese Rat Liver

目的:探讨低氧训练对肥胖大鼠肝脏中mi R-122-5p及其上下游调节因子在转录水平表达的影响,并在细胞中验证mi R-122-5p的表达对下游脂代谢相关基因的调节。方法:雄性SD大鼠经10周高脂饮食诱导建立肥胖大鼠模型,适应性训练后随机分为常氧安静组(N组)和低氧训练组(H组)。4周后测量体重、体脂、血清脂类含量,利用实时荧光定量PCR检测肝脏中mi R-122-5p及上下游调节因子转录水平的相对表达。将大鼠正常肝细胞BRL-3A分为未转染组(C组)、过表达mi R-122-5p组(Up组)、抑制表达mi R-122-5p组(Down组)和空载体组(Nc组),慢病毒转染建立稳定转染细胞系,利用实时荧光定量PCR检测mi R-122-5p及下游脂代谢调节因子转录水平的相对表达。结果:与N组相比,H组大鼠体重、体脂显著降低(P<0.01),血清脂类含量显著改善(P<0.05或P<0.01),肝脏mi R-122-5p及C/EBPα、SREBP-1c、FASN、ACC1 m RNA的相对表达水平显著降低(P<0.05或P<0.01),HIF-1α、CPT1A m RNA的相对表达水平显著升高(P<0.05或P<0.01)。在BRL-3A细胞中过表达或抑制表达mi R-122-5p,导致SREBP-1c、FASN、ACC1 m RNA相对表达水平显著升高或降低(P<0.05或P<0.01),CPT1A m RNA的相对表达水平显著降低或升高(P<0.05或P<0.01)。结论:低氧训练可能通过HIF-1α-mi R-122-5p-SREBP-1c途径调节肥胖大鼠肝脏脂代谢,低氧训练诱导HIF-1α的表达升高,依次下调C/EBPα和mi R-122-5p的表达,进而通过升高SREBP-1c、FASN、ACC1和降低CPT1A的表达,抑制肝脏中脂肪酸的合成,促进脂肪酸的氧化,改善肝脏脂类的代谢。

Objective： To investigate the effects of hypoxic training on the expression of miR-122-5 p and the transcriptional levels of lipid metabolism regulatory factors in the liver of obese rats, and to verify the role of miR-122-5 p on the expression of lipid metabolism related genes in vitro, to investigate the mechanism of miR-122-5 p in regulating liver lipid metabolism during hypoxic training.Methods： Male Sprague-Dawley（SD） rats were induced to establish obese rat model by high-fat diet for 10 weeks. After adaptive training, obese rats were randomly divided into two groups： normoxic sedentary group（N group） and hypoxic training group（H group）. 4 weeks later, body weight, body fat and serum lipid content of rats were measured, and the relative expression of miR-122-5 p and transcription level of lipid metabolism important regulatory factors in liver were detected by real-time quantitative PCR. The BRL-3 A cells were divided into four groups： untransfected group（C group）,overexpression miR-122-5 p group（Up group）, suppressive expression miR-122-5 p group（Down group） and empty vector group（Nc group）. The cells were transfected with lentivirus to establish stable transfection cell lines. Real-time quantitative PCR was used to detect the relative expression levels of miR-122-5 p and lipid metabolism regulating factors. Results： Compared with N group, the body weight and body fat of rats in H group decreased significantly（P〈0.01）, and the serum lipid concentration significantly improved（P〈0.05 or P〈0.01）. The relative expression levels of miR-122-5 p andC/EBPα, SREBP-1 c, FASN, ACC1 m RNA were significantly down-regulated（P〈0.05 or P〈0.01）,and the relative expression levels of HIF-1α and CPT1 A m RNA were significantly up-regulated（P〈0.05 or P〈0.01） in H group. Overexpression or inhibition of miR-122-5 p in BRL-3 A cell resulted in a significant increase or decrease in the relative expression levels of SREBP-1 c, FASN, ACC1 m RNA（P〈0.05 or P〈0.01）, while the relative expression level of CPT1 A m RNA was significantly decreased or increased（P〈0.05 or P〈0.01）. Conclusions： Hypoxic training may regulate lipid metabolism by HIF-1α-miR-122-5 p-SREBP-1 c in obese rat liver. Hypoxic training increased the expression of HIF-1α in the liver of obese rats, and down-regulated the expression of C/EBPα and miR-122-5 p in turn,then inhibited the synthesis of fatty acids by decreasing the expression of SREBP-1 c, FASN and ACC1,and promoted the oxidation of fatty acids by increasing the expression of CPT1 A, to play a role in regulating lipid metabolism in the liver.