Epigenetic changes induced by in utero dietary challenge result in phenotypic variability in successive generations of mice [BS-seq]. Epigenetic changes induced by in utero dietary challenge result in phenotypic variability in successive generations of mice [BS-seq]

Transmission of epigenetic information between generations occurs in nematodes, flies and plants, mediated by specialised small RNA pathways, modified histones and DNA methylation. In mammals, evidence supports similar trans- and inter-generational effects although the underlying mechanisms are incompletely understood. Here a luciferase knock-in reporter mouse for the imprinted Dlk1 locus was generated to visualise and track epigenetic fidelity across generations. Exposure to high-fat diet (HFD) in pregnancy provoked sustained re-expression of the normally silent maternal Dlk1 allele in offspring (a loss of imprinting) and increased DNA methylation at the sDMR. In the next generation heterogeneous Dlk1 mis-expression was seen exclusively among animals born to F1-exposed females. Oocytes from these females showed altered gene and miR expression without changes in DNA methylation, and correct imprinting was restored in subsequent generations. Our results illustrate how diet impacts the foetal epigenome, disturbing canonical and non-canonical imprinting mechanisms to modulate the properties of two successive generations of offspring. Overall design: A total of 78 MII oocytes, 41 from F1 mat-CD mice and 37 from F1 mat-HFD mice.

跨代表观遗传信息传递现象存在于线虫、果蝇与植物中，其介导机制包括特异性小RNA通路、修饰组蛋白以及DNA甲基化。在哺乳动物中，已有证据支持存在类似的跨代与代间效应，但相关潜在机制尚未完全阐明。本研究构建了针对印记型Dlk1基因座的荧光素酶（Luciferase）敲入报告小鼠，用于可视化追踪跨代表观遗传保真度。孕期暴露于高脂饮食（high-fat diet, HFD）可引发后代中原本沉默的母源Dlk1等位基因持续重新表达（即印记丢失），并使sDMR区域的DNA甲基化水平升高。在下一代中，仅在经高脂饮食暴露的F1代母鼠所产后代中观察到异质性的Dlk1异常表达。这些母鼠的卵母细胞呈现基因与微小RNA（miR）表达异常，但DNA甲基化水平未发生改变，且后续世代的印记状态可恢复正常。本研究结果阐明了饮食如何影响胎儿表观组，通过干扰经典与非经典印记调控机制，从而调控连续两代后代的表型特征。
实验整体设计：共收集78枚MII期卵母细胞，其中41枚来自F1代母源对照饮食组（F1 mat-CD）的小鼠，37枚来自F1代母源高脂饮食组（F1 mat-HFD）的小鼠。