Integrated analysis of lncRNAs and mRNA expression profiles reveals the potential role of lncRNAs in different bovine lactation stages

Long non-coding RNAs (lncRNAs) play a critical role in mammary development and breast cancer biology. Despite their important role in the mammary gland, little is known on the roles of lncRNAs in bovine lactation, particularly regarding the molecular processes underlying it. To characterize the role of lncRNAs in bovine lactation, four samples of Holstein cow mammary gland tissue at peak and late lactation stages were examined after biopsy. We then profiled the transcriptome of mammary gland using RNA sequencing technology. Further, functional lncRNA-mRNA co-expression pairs were constructed to infer the function of lncRNAs using a generalized linear model, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Over 1000 putative lncRNAs were identified, 117 of which were differentially expressed between peak and late lactation stages. Bovine lncRNAs were shorter, with fewer exon numbers, and expressed at significantly lower levels than protein-coding genes. Seventy-two differentially expressed lncRNAs (DE-lncRNAs) were co-expressed with 340 different protein-coding genes. The KEGG pathway analysis showed that target mRNAs for DE-lncRNAs were mainly related to lipid and glucose metabolism, including the peroxisome proliferator-activated receptors (PPAR) and 5' adenosine monophosphate-activated protein kinase (AMPK) signaling pathways. Further bioinformatics and integrative analyses revealed that 12 DE-lncRNAs potentially played important roles in bovine lactation. Our findings provide a valuable resource for future bovine transcriptome studies, facilitate the understanding of bovine lactation biology, and offer functional information for cattle lactation.Keywords: Long non-coding RNA, bovine lactation, mammary gland, co-expression, RNA sequencing