Long Non-Coding RNA- Occurrence and Emerging Roles in the Bovine Genome

The vast majority of mammalian non-coding RNA transcripts are long non-coding RNA (lncRNA). Emerging research indicates roles for lncRNAs in many biological processes, tissue specificity and association with disease as well as a myriad of functions. While extensive work has been done on the identification and functional characterization of lncRNA in the human genome, the lncRNA repertoire of the bovine genome and other farm animal species is less explored. Recently, we have characterized the lncRNA transcriptome of the bovine mammary gland and gastro-intestinal-tract (GIT) of calves. We identified 4955 lncRNAs in the mammary gland of mi-lactation Holstein cows including 32 lncRNAs that were differentially expressed (DE) following dietary supplementation with 5% linseed oil. Some DE lncRNAs were collocated with reported QTL for fat and lactation traits. Enrichment of positional genes nearby DE lncRNAs revealed metabolic pathways and biological processes (cytokines, immunological and hormone responses) significant for regulatory networks of lncRNAs. Weighted correlation network analysis identified important modules and key lncRNAs for milk fat, protein and urea, and blood triglyceride and non-esterified fatty acid. Additionally, we identified 1991 and 4244 lncRNAs in the ileum and colon tissues of calves, respectively. Moreover, 12 and 500 lncRNAs were DE between ileum and rumen tissues, respectively, collected during the pre-weaning and the post-weaning periods. Furthermore, 19 lncRNAs were common between ileum and mammary gland tissue, 43 between ileum and rumen and one between rumen and mammary gland tissue. This data suggest roles for lncRNA in mammary lipogenesis, lipid synthesis/metabolism, and in the growth and development of the GIT.