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MicroRNA-141 participates in milk lipid metabolism by targeting SIRT1 in bovine mammary epithelial cells

Context The regulation of milk lipids is important for the evaluation of dairy cows’ performance. Lipids are produced and secreted by mammary gland under the regulation of steroid hormones, growth factors and microRNAs (miRNAs). MicroRNAs have been verified to be involved in numerous biological processes. Previous studies have shown that miR-141 is expressed at higher levels in dairy cows at peak lactation than in those at early lactation. However, the roles of miR-141 in bovine mammary epithelial cells (BMECs) and the mechanisms how it affects lipid metabolism are as yet unknown. Aims The aims of this study were to clarify (i) the molecular mechanisms of miR-141 in milk lipid metabolism, and (ii) how miR-141 affects milk lipid metabolism in BMECs. Methods Triglycerides were observed in BMECs using triglyceride analysis after overexpression or inhibition of miR-141; selected potential candidate genes that are targeted by miR-141 using TargetScan. The regulatory relationship among miR-141, SIRT1 gene and lipid metabolism-related genes (SREBF1, FASN and PPARγ) by using the dual luciferase assay, quantitative real-time PCR and western blotting. Key results Through overexpression or inhibition of miR-141 expression, we found that miR-141 promoted lipid metabolism in BMECs and an increase in triglycerides was observed in these cells. Further, miR-141 targets the 3′UTR of SIRT1 mRNA, and negative regulates the expression of SIRT1 gene in BMECs. Also, the expression levels of SREBF1, FASN and PPARγ, which are related to milk lipid metabolism, were also altered after overexpression miR-141. Conclusions Our results have revealed that miR-141 could promote milk lipid metabolism in BMECs by means of negative regulates SIRT1 gene and positive effects lipid metabolism-related genes (SREBF1, FASN and PPARγ) in BMECs. Implications Our research indicates that miR-141 could be considered a marker in cattle breeding to obtain high quality dairy products. It would be useful to study the function of miRNAs in milk lipid metabolism and synthesis. In the long term these findings might be helpful in developing practical means to improve the quality of ruminant milk.