CircRNA is a specific type of non-coding RNA that has been shown to have an important role in mammary gland (MG) activity, but no study of MG circRNA activity in sheep so far. In this study, the expression profile of circRNAs was investigated using RNA-Seq in MG parenchyma at peak lactation from Small-Tailed Han sheep and Gansu Alpine Merino sheep with phenotypic differences in milk yield and components. A total of 4, 906 circRNAs were found and 33 of these were differentially expressed between breeds. GO and KEGG results showed that the parental genes of differentially expressed circRNAs were mainly enriched in heterocyclic compound binding, kinase activity, adherens junction, the TGF-β signaling pathway, and the MAPK signaling pathway. This study provides an overview of circRNA expression in the ovine MG and the interaction between some key circRNAs and their target miRNAs. It improves our knowledge of the role of circRNA in sheep milk synthesis.

CircRNA是非编码RNA的一种特殊类型，已显示在乳腺（MG）活性中具有重要作用，但到目前为止，尚未对绵羊MG circRNA活性进行研究。在这项研究中，研究了在小尾寒羊和甘肃高山美利奴羊泌乳高峰时，MG薄壁组织中RNA序列在MG薄壁组织中的表达情况，其中奶产量和成分存在表型差异。总共发现了4906个circRNA，其中33个在不同品种之间差异表达。GO和KEGG结果表明，差异表达的circRNA的亲本基因主要富集杂环化合物结合，激酶活性，粘附连接，TGF-β信号通路和MAPK信号通路。这项研究概述了绵羊MG中circRNA的表达以及一些关键circRNA及其靶标miRNA之间的相互作用。它提高了我们对circRNA在羊乳合成中作用的认识。