miR-27a suppresses triglyceride accumulation and affects gene mRNA expression associated with fat metabolism in dairy goat mammary gland epithelial cells

• A correlation exists between miR-27a and milk triglyceride accumulation in goat.
• miR-27a expression correlates with lactation cycle and prolactin concentration.
• Over-expression of miR-27a decreases triglyceride and fatty acid contents.
• Over-expressed miR-27a suppresses the ratio of unsaturated/saturated fatty acid.
• miR-27a significantly affects gene mRNA expression related to milk fat metabolism.

MicroRNAs (miRNAs), a well-defined group of small RNAs containing about 22 nucleotides, participate in various biological metabolic processes. miR-27a is a miRNA that is known to regulate fat synthesis and differentiation in preadipocyte cells. However, little is known regarding the role that miR-27a plays in regulating goat milk fat synthesis. In this study, we determined the miR-27a expression profile in goat mammary gland and found that miR-27a expression was correlated with the lactation cycle. Additionally, prolactin promoted miR-27a expression in goat mammary gland epithelial cells. Further functional analysis showed that over-expression of miR-27a down-regulated triglyceride accumulation and decreased the ratio of unsaturated/saturated fatty acid in mammary gland epithelial cells. miR-27a also significantly affected mRNA expression related to milk fat metabolism. Specifically, over-expression of miR-27a reduced gene mRNA expression associated with triglyceride synthesis by suppressing PPARγ protein levels. This study provides the first experimental evidence that miR-27a regulates triglyceride synthesis in goat mammary gland epithelial cells and improves our understanding about the importance of miRNAs in milk fat synthesis.