MicroRNA transcriptome in weaning and sucking porcine intestines. Sus scrofa

MicroRNAs (miRNAs) play important roles in intestinal diseases; however, the role of miRNAs during weaning stress is unknown. In our study, six jejunal small RNA libraries constructed from weaning piglets at 1, 4 and 7 d after weaning (libraries W1, W4 and W7, respectively) and from suckling piglets on the same days as the weaning piglets (libraries S1, S4 and S7, respectively) were sequenced using Solexa high-throughput sequencing technology. Overall, 260 known swine miRNAs and 317 novel candidate miRNA precursors were detected in the six libraries. The results revealed that 16 differentially expressed miRNAs were found between W1 and S1; 98 differentially expressed miRNAs were found between W4 and S4 (ssc-mir-146b had the largest difference and ssc-mir-215 had the highest expression level); and 22 differentially expressed miRNAs were found between W7 and S7. Sequencing miRNA results were validated using RT-qPCR. Approximately 12,819 miRNA-mRNA interactions corresponding to 4,250 target genes were predicted. The biological analyses revealed that the differentially expressed miRNAs regulated small intestinal metabolism, stressful responses, cellular and immune functions and miRNA biosynthesis in piglets. Therefore, the small intestine miRNA transcriptome was significantly different between weaning and suckling piglets; the difference varied with the number of days after weaning. Overall design: six small RNA libraries from weaning piglets at 1, 4 and 7 d after weaning and from suckling piglets on the same days as the weaning piglets, respectively. For every small RNA library construction, 4 biological total RNA samples isolated from each treatment and control were separately pooled with equal contribution.