MicroRNA-mRNA regulatory network related to lipid metabolism in bovine mammary epithelial cells

Abstract Milk fat percentage is an important factor of milk quality in dairy cattle. Functional microRNAs and genes can affect lipid synthesis and metabolism through differential expression in bovine mammary epithelial cells (BMECs). It is necessary to screening the crucial candidate gene and miRNA on milk fat percentage. In this study, we extract total RNA of BMECs isolated from Chinese Holstein cows with high and low milk fat percentages for the conjoint analysis of RNA-seq and Solexa sequencing data. 190 differentially expressed genes and 33 differentially expressed microRNAs (DERs) were enriched in 488 GO terms and 12 KEGG pathways significantly (p <0.05) based on the conjoint analysis. The detection of triglyceride production in BMECs showed that bta-miR-21-3p and bta-miR-148a promote triglyceride synthesis, whereas bta-miR-124a, bta-miR-877, bta-miR-2382-5p and bta-miR-2425-5p inhibit triglyceride synthesis. Meanwhile, the target relationships between PDE4D and bta-miR-148a, PEG10 and bta-miR-877, SOD3 and bta-miR-2382-5p, and ADAMTS1 and bta-miR-2425-5p were verified using luciferase reporter assays and quantitative RT-PCR. The conjoint analysis can more accurately screen candidate regulator related to milk fat percentage at the molecular level, which provided a scientific research method screening functional miRNA and gene for the breeding of new high-quality dairy cows.