title: miR-27a controls triacylglycerol synthesis in bovine mammary epithelial cells by targeting peroxisome proliferator-activated receptor gamma.
abstract: Growing evidence has revealed that microRNA are central elements in milk fat synthesis in mammary epithelial cells. A negative regulator of adipocyte fat synthesis, miR-27a has been reported to be involved in the regulation of milk fat synthesis in goat mammary epithelial cells; however, the regulatory role of miR-27a in bovine milk fat synthesis remains unclear. In the present study, primary bovine mammary epithelial cells (BMEC) were harvested from mid-lactation cows and cultured in Dulbecco's modified Eagle's medium/F-12 medium with 10% fetal bovine serum, 5 μg/mL of insulin, 1 μg/mL of hydrocortisone, 2 μg/mL of prolactin, 1 μg/mL of progesterone, 100 U/mL of penicillin, and 100 μg/mL of streptomycin. We found that the overexpression of miR-27a significantly suppressed lipid droplet formation and decreased the cellular triacylglycerol (TAG) levels, whereas inhibition of miR-27a resulted in a greater lipid droplet formation and TAG accumulation in BMEC. Meanwhile, overexpression of miR-27a inhibited mRNA expression of peroxisome proliferator-activated receptor gamma (PPARG), CCAAT/enhancer-binding protein beta (C/EBPβ), perilipin 2 (PLIN2), and fatty acid binding protein 3 (FABP3), whereas miR-27a downregulation increased PPARG, C/EBPβ, FABP3, and CCAAT enhancer binding protein alpha (C/EBPα) mRNA expression. Furthermore, Western blot analysis revealed the protein level of PPARG in miR-27a mimic and inhibitor transfection groups to be consistent with the mRNA expression response. Moreover, luciferase reporter assays verified that PPARG was the direct target of miR-27a. In summary, these results indicate that miR-27a has the ability to control TAG synthesis in BMEC via targeting PPARG, suggesting that miR-27a could potentially be used to improve beneficial milk components in dairy cows.
authors.affiliation: College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors.forename: K Q
authors.initials: KQ
authors.lastname: Tang
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors.forename: Y N
authors.initials: YN
authors.lastname: Wang
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China. Electronic address: zanlinsen@163.com.
authors.forename: L S
authors.initials: LS
authors.lastname: Zan
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China. Electronic address: yangwucai111@163.com.
authors.forename: W C
authors.initials: WC
authors.lastname: Yang
mesh_terms: D000818:Animals; D002417:Cattle; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D050155:Lipogenesis / Q000235:genetics; D008321:Mammary Glands, Animal / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics; D047495:PPAR gamma / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
chemical_list: D035683:MicroRNAs; D047495:PPAR gamma; D014280:Triglycerides
keywords: PPARG; bovine mammary epithelial cell; miRNA-27a; triacylglycerol synthesis