Abstract
MicroRNAs (miRNAs) are mRNA suppressors that regulate a variety of cellular and physiological processes, including cell proliferation, apoptosis, triglyceride synthesis, fat formation, and lipolysis, by post-transcriptional processing. In previous studies, we isolated and sequenced miRNAs from mammary epithelial cells from Chinese Holstein cows with high and low milk fat percentages. MiR-485 was one of the significantly differentially expressed miRNAs that were identified. In the present study, the relationship between the candidate target gene DTX4 and miR-485 was validated by bioinformatics and real-time fluorescent quantitative PCR (qRT-PCR) and Western blot (WB) analyses in bovine mammary epithelial cells (bMECs). The results indicated that miR-485 negatively regulated the mRNA expression of the target gene DTX4. Furthermore, an shRNA interference vector for the target gene DTX4 was constructed successfully, and it increased the triglyceride content and reduced the cholesterol content of transfected cells. These results suggest that miR-485 may affect the contents of triglycerides (TGs) and cholesterol (CHOL) by targeting the DTX4 gene. This study indicates that miR-485 has a role in regulating milk fat synthesis and that miR-485 targets the DTX4 gene to regulate lipid metabolism in bMECs. These findings contribute to the understanding of the functional significance of miR-485 in milk fat synthesis.