Identification of Differentially Expressed MicroRNAs and Their Potential Target Genes in Adipose Tissue from Pigs with Highly Divergent Backfat Thickness

SIMPLE SUMMARY: The role of microRNA in fat deposition is very important and not clearly understood. We detected 318 pig microRNAs (miRNAs), among high and low backfat tissue samples, by high throughput sequencing. Among them, 18 miRNAs were differentially expressed between the high and low backfat groups. Some of the differentially expressed miRNAs were involved mainly in lipid and carbohydrate metabolism, and glycan biosynthesis and metabolism. In addition, in silico analysis of the mRNA and miRNA transcriptomes, revealed possible regulatory relationships for fat deposition. In particular, three miRNA–mRNA pairs, miR-137–PPARGC1A, miR-141–FASN, and miR-122-5p–PKM, were identified as candidate key regulators of fat deposition. Our findings provide an important insight into miRNA expression patterns in backfat tissue of pig and new insights into the regulatory mechanisms of fat deposition in pig. ABSTRACT: Fatty traits are very important in pig production. However, the role of microRNAs (miRNAs) in fat deposition is not clearly understood. In this study, we compared adipose miRNAs from three full-sibling pairs of female Landrace pigs, with high and low backfat thickness, to investigate the associated regulatory network. We obtained an average of 17.29 million raw reads from six libraries, 62.27% of which mapped to the pig reference genome. A total of 318 pig miRNAs were detected among the samples. Among them, 18 miRNAs were differentially expressed (p-value < 0.05, |log(2)fold change| ≥ 1) between the high and low backfat groups; 6 were up-regulated and 12 were down-regulated. Functional enrichment of the predicted target genes of the differentially expressed miRNAs, indicated that these miRNAs were involved mainly in lipid and carbohydrate metabolism, and glycan biosynthesis and metabolism. Comprehensive analysis of the mRNA and miRNA transcriptomes revealed possible regulatory relationships for fat deposition. Negatively correlated mRNA–miRNA pairs included miR-137–PPARGC1A, miR-141–FASN, and miR-122-5p–PKM, indicating these interactions may be key regulators of fat deposition. Our findings provide important insights into miRNA expression patterns in the backfat tissue of pig and new insights into the regulatory mechanisms of fat deposition in pig.