Liver miRNA profiles of laying hens before and after reaching sexual maturity with a high energy feed during the maturation period

【Objective】In the current study,the liver miRNA profiles of sexually immature and sexually mature laying hens fed with a high energy feed during the maturation period were compared to clarify which liver miRNAs in liver influenced sexual maturity with high energy feed. The study laid a foundation for improving egg production.【Method】High-energy feed with 12.14 MJ/kg metabolic energy was used to feed laying hens during the maturation period. Liver miRNAs were detected by small RNA sequencing with the Illumina NextSeq500 platform in sexually mature (R) and sexually immature(N) laying hens. miRNA expression was analyzed using the bioinformatics software DESeq and validated using qRT-PCR. Target genes and target sites of differentially expressed miRNAs were predicted by miRanda and the differentially targeted genes were analyzed for GO and KEGG enrichment using a hypergeometric distribution.【Result】More than 300 miRNAs could be annotated in each of the 6 samples(3 R and 3 N),accounting for about 30.00% of the identified chicken miRNAs in miRBase. The results from precursor identification showed that some annotated miRNAs in each sample were located on the same precursor. Compared with the N group,the expression levels of 9 miRNAs in the R group were up-regulated and 3 miRNAs were down-regulated,among which gga-miR-132c-5p,gga-miR-132b-5p, gga-miR-2184a-5p,gga-miR-132c-3p,gga-miR-132b-3p and gga-miR-2184a-3p were in a miRNA cluster. In addition,3 upregulated miRNAs in the R group,including gga-miR-1682,gga-miR-132b-3p and gga-miR-2184a-3p,were not expressed in the N group. A total of 129 target genes of the differentially expressed genes were predicted by miRanda. The number of target genes predicted for gga-miR-203a was the highest(32), gga-miR-2184a-5p,gga-miR-148a-5p and ggamiR-12211-5p showed a smaller number(30,25 and 23,respectively) and miR-132c-5p the lowest(only 9). GO analysis of the 129 differentially targeted genes showed that there were 8 significantly enriched GO terms,including 7 biological processes:lipid metabolism,cellular lipid metabolism,lipid biosynthesis,phospholipid biosynthesis,phospholipid metabolism,glycerophospholipid biosynthesis and anatomical structure development. No cellular component terms were found and only 1 molecular function term was detected:natriuretic peptide receptor activity. In the 8 enriched GO items,6 were related to lipid metabolism,and 22 target genes were involved,accounting for 17.10% of the 129 genes. KEGG analysis showed that there were 7 significant enriched KEGG terms,of which fatty acid degradation,fatty acid biosynthesis,synthesis and degradation of ketone bodies and PPAR signaling pathway were related to lipid metabolism.【Conclusion】A total of 12 miRNAs are differentially expressed between sexually immature and sexually mature laying hens under a high energy feeding regime during the maturation period,involving 129 potential differentially expressed genes,which are mainly enriched in processes and pathways related to lipid metabolism in the liver. The data suggests that miRNAs affect sexual maturity of laying hens by regulating lipid metabolism and related genes.