Background miRNA has an important role in cell differentiation, biological development, and physiology. Milk production is an important quantitative trait in livestock and miRNA plays a role in the amount of milk produced. Methods The role of regulatory miRNAs involved in equine milk production is not fully understood. We constructed two miRNA libraries for Kazakh horse milk production from higher-producing (H group) and lower-producing (L group) individuals, and used RNA-Seq technology to identify the differentially expressed miRNAs between the two milk phenotypes of Kazakh horses. Results A total of 341 known and 333 novel miRNAs were detected from the H and L groups, respectively. Eighty-three differentially expressed miRNAs were identified between the H and L group s, of which 32 were known miRNAs (27 were up-regulated, five were down-regulated) and 51 were novel miRNAs (nine were up-regulated, 42 were down-regulated). A total of 2,415 genes were identified. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that these genes were annotated to mammary gland development, mammary gland morphogenesis, tissue development and PI3K-Akt signaling pathways, insulin signaling pathway and TGF-beta signaling pathway, among others. Five miRNAs (miR-199a-3p, miR143, miR145, miR221, miR486-5p) were identified as affecting horse milk production and these five miRNAs were validated using qRT-PCR. Conclusions We described a methodology for the transcriptome-wide profiling of miRNAs in milk, which may help the design of new intervention strategies to improve the milk yield of Kazakh horses.

中文翻译：

---

使用 RNA 测序评估哈萨克马早期妊娠期间的关键 miRNA

背景 miRNA 在细胞分化、生物发育和生理学中具有重要作用。产奶量是家畜的重要数量性状，miRNA在产奶量中起作用。方法 调节性 miRNA 在马奶生产中的作用尚不完全清楚。我们构建了两个用于生产高产（H 组）和低产（L 组）个体的哈萨克马奶的 miRNA 文库，并使用 RNA-Seq 技术鉴定了哈萨克马两种奶表型之间差异表达的 miRNA。结果H组和L组分别检测到341个已知miRNA和333个新miRNA。在 H 组和 L 组之间鉴定出 83 个差异表达的 miRNA，其中 32 个是已知的 miRNA（27 个上调，5 个被下调），51 个是新的 miRNA（9 个被上调，42 个被下调）。共鉴定了 2,415 个基因。基因本体论（GO）和京都基因和基因组百科全书（KEGG）通路分析表明，这些基因被注释到乳腺发育、乳腺形态发生、组织发育和PI3K-Akt信号通路、胰岛素信号通路和TGF-β信号通路。通路等。五种 miRNA（miR-199a-3p、miR143、miR145、miR221、miR486-5p）被确定为影响马奶产量，并使用 qRT-PCR 验证了这五种 miRNA。结论 我们描述了一种对牛奶中 miRNA 进行全转录组分析的方法，这可能有助于设计新的干预策略以提高哈萨克马的产奶量。