Li Bo, Zhang Zhiguo, Zhang Huizhi, Quan Kai, Lu Yan, Cai Dongsheng, Ning Guang
Shanghai Institute of Endocrine and Metabolic DiseasesShanghai Clinical Center for Endocrine and Metabolic Diseases, RuiJin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai 200025, ChinaDepartment of NeurosurgeryHuashan Hospital of Fudan University, Shanghai 200040, ChinaDepartment of Molecular PharmacologyAlbert Einstein College of Medicine, Bronx, New York 10461, USA.
Shanghai Institute of Endocrine and Metabolic DiseasesShanghai Clinical Center for Endocrine and Metabolic Diseases, RuiJin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai 200025, ChinaDepartment of NeurosurgeryHuashan Hospital of Fudan University, Shanghai 200040, ChinaDepartment of Molecular PharmacologyAlbert Einstein College of Medicine, Bronx, New York 10461, USA
J Mol Endocrinol. 2014 Dec;53(3):393-403. doi: 10.1530/JME-14-0127. Epub 2014 Oct 13.
The prevalence of non-alcoholic fatty liver disease (NAFLD), a condition characterized by an excessive accumulation of triglycerides (TGs) in hepatocytes, has dramatically increased globally during recent decades. MicroRNAs (miRs) have been suggested to play crucial roles in many complex diseases and lipid metabolism. Our results indicated that miR199a-5p was remarkably upregulated in free fatty acid (FA)-treated hepatocytes. To investigate the role of miR199a-5p in the pathogenesis of fatty liver and the potential mechanism by which miR199a-5p regulates NAFLD, we first transfected two hepatocyte cell lines, HepG2 and AML12 cells, with agomiR199a-5p or antagomiR199a-5p. Our results indicated that miR199a-5p overexpression exacerbated deposition of FA and inhibited ATP levels and mitochondrial DNA (mtDNA) contents. Consistently, suppression of miR199a-5p partially alleviated deposition of FA and increased ATP levels and mtDNA contents. Moreover, miR199a-5p suppressed the expression of mitochondrial FA β-oxidation-related genes through inhibition of caveolin1 (CAV1) and the related peroxisome proliferator-activated receptor alpha (PPARα) pathway. Furthermore, suppression of CAV1 gene expression by CAV1 siRNA inhibited the PPARα signalling pathway. Finally, we examined the expression of miR199a-5p in liver samples derived from mice fed a high-fat diet, db/db mice, ob/ob mice and NAFLD patients, and found that miR199a-5p was upregulated while CAV1 and PPARA were downregulated in these systems, which was strongly indicative of the essential role of miR199a-5p in NAFLD. In summary, miR199a-5p plays a vital role in lipid metabolism, mitochondrial activity and mitochondrial β-oxidation in liver. Upregulated miR199a-5p in hepatocytes may contribute to impaired FA β-oxidation in mitochondria and aberrant lipid deposits, probably via CAV1 and the PPARα pathway.
非酒精性脂肪性肝病（NAFLD）是一种以肝细胞内甘油三酯（TGs）过度蓄积为特征的疾病，近几十年来在全球范围内的患病率急剧上升。微小RNA（miRs）已被认为在许多复杂疾病和脂质代谢中起关键作用。我们的结果表明，miR199a - 5p在游离脂肪酸（FA）处理的肝细胞中显著上调。为了研究miR199a - 5p在脂肪肝发病机制中的作用以及miR199a - 5p调节NAFLD的潜在机制，我们首先用agomiR199a - 5p或antagomiR199a - 5p转染两种肝细胞系，HepG2和AML12细胞。我们的结果表明，miR199a - 5p过表达加剧了FA的沉积，并抑制了ATP水平和线粒体DNA（mtDNA）含量。一致地，抑制miR199a - 5p可部分减轻FA的沉积，并增加ATP水平和mtDNA含量。此外，miR199a - 5p通过抑制小窝蛋白1（CAV1）和相关的过氧化物酶体增殖物激活受体α（PPARα）途径，抑制线粒体FAβ - 氧化相关基因的表达。此外，CAV1 siRNA抑制CAV1基因表达可抑制PPARα信号通路。最后，我们检测了高脂饮食喂养的小鼠、db/db小鼠、ob/ob小鼠和NAFLD患者肝脏样本中miR199a - 5p的表达，发现这些模型中miR199a - 5p上调，而CAV1和PPARA下调，这强烈表明miR199a - 5p在NAFLD中起重要作用。总之，miR199a - 5p在肝脏脂质代谢、线粒体活性和线粒体β - 氧化中起重要作用。肝细胞中miR199a - 5p上调可能通过CAV1和PPARα途径导致线粒体中FAβ - 氧化受损和异常脂质沉积。
