Identification of key miRNAs regulating fat metabolism based on RNA-seq from fat-tailed sheep and F2 of wild Argali

Abstract

The evolution mechanism of sheep tail fat has not yet been clear, many researches focus on this issue, yet there still many gaps to be filled in the targets and non-coding RNA regulation. In our study, the differential expression mRNAs and miRNAs were detected by RNA-seq and constructed a mRNA-miRNA network related to the lipid deposition in tail of fat-tailed sheep and F2 of Argali with domestic sheep (thin-tailed). Then 6 kinds of tissues from thin-tailed and control group were extracted for function validation of candidate genes and its regulator miRNAs. 125 differentially expressed miRNAs were identified by RNA-seq, and enrichment analysis of their target genes revealed 10 significantly enriched pathways related to lipid metabolism. In these pathways, 126 DE-miRNA target genes were also differentially expression in the same tissues in our previous transcriptomic data. In PPI network, 6 hubgenes (SCD, ACACA, GPD2, ELOVL6, ELOVL5, GPAM) were extracted using the cytoHubba application, and they may be target genes for 3 candidate DE-miRNAs (miR-320d, miR-151b, miR-6715). The validation results of RT-qPCR show: the expression trend of miR-320d is opposite to the target gene SCD, and that of miR-151b and the target gene ACACA are also opposite in 6 tissues, implying that they may have direct targeting relationships. Moreover, the expression of miR-320d in F2 tail fat was significantly higher than that in fat-tailed sheep (P < 0.05), and the expression of SCD in F2 tail fat was extremely significantly lower than that in fat-tailed sheep (P < 0.01). The expression of miR-151b in F2 tail fat and subcutaneous fat was significantly higher than that in fat-tailed sheep (P < 0.05), and the expression of ACACA in F2 subcutaneous fat was significantly lower than that in fat-tailed sheep. miR-320d may directly and negatively regulate tail fat deposition by targeting SCD, while miR-151b may indirectly and negatively regulate tail fat deposition by targeting ACACA.

Keywords: Expression patterns; RNA-seq; Tail fat; Wild Argali; miRNAs.