miR-25 modulates triacylglycerol and lipid accumulation in goat mammary epithelial cells by repressing PGC-1beta

Background: The goat (Caprahircus) is one of the most important livestock animals. Goat milk fat is an important component in the nutritional quality of goat milk. Growing evidence points to the critical roles of microRNAs (miRNAs) in lipid metabolism. Results: Using a highly sensitive method of S-poly(T) plus for miRNAs detection, we analyze the expression patterns of 715 miRNAs in goat mammary gland tissues at different stages of lactation. We observed that miR-25 expression had an inverse relationship with milk production. Overexpression of miR-25 significantly repressed triacylglycerol synthesis and lipid droplet accumulation. To explore the regulatory mechanism of miR-25 in milk lipid metabolism, we analyzed its putative target genes with bioinformatics analysis followed by 3'-UTR assays. Peroxisome proliferative activated receptor gamma coactivator 1 beta (PGC-1beta), a key regulator of lipogenics was identified as a direct target of miR-25 with three specific sites within its 3'-UTR, In addition, miR-25 mimics in goat mammary epithelial cells reduced the expressions of genes involved in lipid metabolism. Conclusions: Taken together, our results show miR-25 is potentially involved in lipid metabolism and we reveal the function of the miR-25/PGC-1beta regulatory axis during lactation.