MicroRNAs (miRNAs) are small non-coding RNAs that are involved in mammary gland development and lactation in livestock. Little is known about the roles of miRNAs in ovine mammary gland development, hence in this study the expression profiles of miRNAs of the mammary gland tissues of ewes at peak-lactation and during the non-lactating period were investigated using RNA sequencing. A total of 147 mature miRNAs were expressed in the two periods. Compared with peak-lactation, eight miRNAs in the non-lactating ewe mammary gland were significantly up-regulated, whereas fifteen miRNAs were down-regulated. A KEGG analysis revealed that the target genes of the up-regulated miRNAs were significantly enriched in lysosome, Wnt and MAPK signaling pathways, while the target genes of down-regulated miRNAs were significantly enriched in the PI3K-Akt signaling pathway, protein processing in endoplasmic reticulum and axon guidance. These results suggest that further study of the differentially expressed miRNAs could provide a better understanding of the molecular mechanisms of mammary development and lactation in sheep.

MicroRNAs (miRNAs) 是参与家畜乳腺发育和泌乳的小型非编码 RNA。关于 miRNA 在绵羊乳腺发育中的作用知之甚少，因此在本研究中，使用 RNA 测序研究了母羊乳腺组织在哺乳高峰期和非哺乳期的 miRNA 表达谱。两个时期共表达了147个成熟的miRNA。与哺乳高峰期相比，非哺乳期母羊乳腺中的 8 个 miRNA 显着上调，而 15 个 miRNA 下调。KEGG分析显示上调miRNA的靶基因在溶酶体、Wnt和MAPK信号通路中显着富集，而下调的miRNA的靶基因在PI3K-Akt信号通路、内质网蛋白加工和轴突引导中显着富集。这些结果表明，进一步研究差异表达的 miRNA 可以更好地理解绵羊乳腺发育和泌乳的分子机制。