Modulation of miRNA Expression by Dietary Polyphenols in apoE Deficient Mice: A New Mechanism of the Action of Polyphenols

BackgroundPolyphenols are the most abundant antioxidants in the human diet and are widespread constituents of fruits and beverages, such as tea, coffee or wine. Epidemiological, clinical and animal studies support a role of polyphenols in the prevention of various diseases, such as cardiovascular diseases, cancers or neurodegenerative diseases. Recent findings suggest that polyphenols could interact with cellular signaling cascades regulating the activity of transcription factors and consequently affecting the expression of genes. However, the impact of polyphenol on the expression of microRNA, small non-coding RNAs, has not yet been studied. The aim of this study was to investigate the impact of dietary supplementation with polyphenols at nutritional doses on miRNA expression in the livers of apolipoprotein E-deficient mice (apoE−/−) jointly with mRNA expression profiling. Methodology/Principal FindingsUsing microarrays, we measured the global miRNA expression in the livers of wild-type (C57B6/J) mice or apoE−/− mice fed diets supplemented with one of nine different polyphenols or a control diet. This analysis revealed that knock-out of the apoE gene induced significant modulation in the expression of miRNA. Moreover, changes in miRNA expression were observed after polyphenol supplementation, and five miRNAs (mmu-miR-291b-5p, mmu-miR-296-5p, mmu-miR-30c-1*, mmu-miR-467b* and mmu-miR-374*) were identified as being commonly modulated by these polyphenols. We also observed that these polyphenols counteracted the modulation of miRNA expression induced by apoE mutation. Pathway analyses on these five miRNA-target genes revealed common pathways, some of which were also identified from a pathway analysis on mRNA profiles. ConclusionThis in vivo study demonstrated for the first time that polyphenols at nutritional doses modulate the expression of miRNA in the liver. Even if structurally different, all polyphenols induced a similar miRNA expression profile. Common pathways were identified from both miRNA-target and mRNA analysis, revealing cellular functions that could be regulated by polyphenols at both the miRNA and mRNA level.

研究背景
多酚是人类膳食中含量最为丰富的抗氧化剂，同时也是水果、茶、咖啡、葡萄酒等饮品的常见组成成分。流行病学、临床及动物实验研究均证实，多酚在预防心血管疾病、癌症、神经退行性疾病等多种疾病中发挥关键作用。近期研究表明，多酚可与调控转录因子活性的细胞信号级联反应相互作用，进而影响基因表达。然而，目前尚未有研究探讨多酚对微小RNA（microRNA, miRNA）——一类小型非编码RNA——表达的影响。
本研究旨在探讨以营养剂量膳食补充多酚，对载脂蛋白E敲除小鼠（apolipoprotein E-deficient mice, apoE−/−）肝脏中miRNA表达的影响，并联合开展mRNA表达谱分析。

研究方法与主要结果
我们利用基因芯片（microarrays）检测了野生型（C57B6/J）小鼠与apoE−/−小鼠的肝脏全局miRNA表达水平，这些小鼠分别喂食添加了9种不同多酚的饲料或对照饲料。分析结果显示，敲除apoE基因可显著调控miRNA的表达。此外，多酚补充后可观察到miRNA表达发生改变，其中5种miRNA（mmu-miR-291b-5p、mmu-miR-296-5p、mmu-miR-30c-1*、mmu-miR-467b*及mmu-miR-374*）被证实可被上述多酚共同调控。我们还发现，这些多酚可抵消apoE突变所诱导的miRNA表达改变。对这5种miRNA的靶基因进行通路分析，结果显示存在共同的调控通路，其中部分通路也在mRNA表达谱的通路分析中被鉴定到。

结论
此项体内研究首次证实，以营养剂量补充的多酚可调控肝脏中miRNA的表达。尽管各类多酚的化学结构存在差异，但所有受试多酚均可诱导相似的miRNA表达谱。通过miRNA靶基因与mRNA表达谱分析共同鉴定得到的调控通路，揭示了多酚可同时在miRNA与mRNA层面调控的细胞功能。