Hepatic microRNAome reveals potential microRNA-mRNA pairs association with lipid metabolism in pigs

Objective: As one of the most important metabolic organs, the liver plays vital roles in modulating the lipid metabolism. This study was to compare miRNA expression profiles of the Large White liver between two different developmental periods and to identify candidate miRNAs for lipid metabolism. Methods: Eight liver samples were collected from White Large of 70-day fetus (P70) and of 70-day piglets (D70) (with 4 biologocal repeats at each development period) to construct sRNA libraries. Then the eight prepared sRNA libraries were sequenced using Illumina next-generation sequencing techonogy on HiSeq 2500 platform. Results: As a result, we obtained 346 known and 187 novel miRNAs. Compared with the D70, 55 down- and 61 up-regulated miRNAs were shown to be significantly differentially expressed (DE). GO and KEGG enrichment analysis indicated that these DE miRNAs were mainly involved in growth, development and diverse metabolic processes. They were predicted to regulate lipid metabolism through Adipocytokine signaling pathway, MAPK, AMPK, cAMP, PI3K-AKT, and Notch signaling pathway. miR-122, miR-26a and miR-30a-5p, which play important roles in lipid metabolism, were the most abundantly expressed (miR-122 only in P70). Integration analysis (details of mRNAs sequencing data were shown in another unpublished paper) revealed that many target genes of the DE miRNAs (miR-181b, miR-145-5p, miR-199a-5p and miR-98) might be critical regulators in lipid metabolic process, including ACSL4, ABCA4 and SCD. Thus, these miRNAs were considered to be the promising candidates for lipid metabolism. Conclusion: Our study provides the main differences in the Large White at miRNA level between two different developmental stages. It supplies a valuable database for the further function and mechanism elucidation of miRNAs in porcine liver development and lipid metabolism.