Abstract
Simple SummaryLong non-coding RNAs (lncRNAs) play a key role in regulating the expression level of mRNAs. The expression profiles of ovine mammary gland were investigated in two sheep breeds with divergent milk phenotype using RNA-Seq. A total of 1894 lncRNAs were found to be expressed and 68 of these were differentially expressed between the two breeds. Some important Gene Ontogeny (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were related to lactation and mammary gland morphogenesis were found for the target genes of differentially expressed lncRNAs. This study can improve our understanding of the functions of lncRNAs in the regulation of lactation, milk yield, and milk components in sheep.Long non-coding RNAs (lncRNAs) are a kind of non-coding RNA with >200 nucleotides in length. Some lncRNAs have been proven to have clear regulatory functions in many biological processes of mammals. However, there have been no reports on the roles of lncRNAs in ovine mammary gland tissues. In the study, the expression profiles of lncRNAs were studied using RNA-Seq in mammary gland tissues from lactating Small-Tailed Han (STH) ewes and Gansu Alpine Merino (GAM) ewes with different milk yield and ingredients. A total of 1894 lncRNAs were found to be expressed. Compared with the GAM ewes, the expression levels of 31 lncRNAs were significantly up-regulated in the mammary gland tissues of STH ewes, while 37 lncRNAs were remarkably down-regulated. Gene Ontogeny (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found that the target genes of differentially expressed lncRNAs were enriched in the development and proliferation of mammary epithelial cells, morphogenesis of mammary gland, ErbB signaling pathway, and Wnt signaling pathway. Some miRNA sponges of differentially expressed lncRNAs, reported to be associated with lactation and mammary gland morphogenesis, were found in a lncRNA-miRNA network. This study reveals comprehensive lncRNAs expression profiles in ovine mammary gland tissues, thereby providing a further understanding of the functions of lncRNAs in the lactation and mammary gland development of sheep.
Highlights
Long non-coding RNAs are a type of non-coding RNA that have more than 200 nucleotides [1]
Using a cut-off of FPKM > 0.1 to define expressed Long non-coding RNAs (lncRNAs), a total of 1770 and 1742 lncRNA were detected in ovine mammary gland tissues of Gansu Alpine Merino (GAM) and Small-Tailed Han (STH) ewes, respectively (Figure 1B)
Compared with the expression level of all lncRNAs identified in the study, it was found that the expression of MSTRG.75623.1 was the most abundant in both GAM and STH ewes
Summary
Long non-coding RNAs (lncRNAs) are a type of non-coding RNA that have more than 200 nucleotides [1]. The majority of lncRNAs were found to regulate the mRNAs expression, and lead to the change of phenotype in different ways [4]. Some lncRNAs can act as ‘sponges’ for microRNAs (miRNAs) to inhibit or relieve the repression of target mRNAs by miRNAs, with an accompanying increase in the expression level of mRNAs in mammals [5,6]. Some lncRNAs are transcribed from enhancer regions of mRNAs and can enhance the expression levels of nearby genes in cis [7], while the others can bind and sequester transcription factors, thereby resulting in a reduction in their transcriptional activity [8,9]. LncRNAs can be involved in chromatin modification by forming lncRNA-ribonucleoprotein complexes with ribonucleic acid proteins, and regulate the expression of the target genes [10,11]
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