Abstract：Fatty acid compositions are crucial indicators of milk quality in dairy cow. Long chain fatty acid (LCFA), especially polyunsaturated fatty acids (PUFA) are beneficial in reducing the risk of cardiovascular disease, cancer, and type 2 diabetes in humans (Homo sapiens). However, the metabolic mechanism of LCFA in mammary gland is still unknown. Solute carrier family 27 member 6 (SLC27A6) is a transmembrane protein that could enhance the uptake of LCFA into cells, thus regulating downstream fatty acid (FA) metabolic pathways. But the relationship between SLC27A6 and fatty acid metabolic genes is still unclear. In this study, SLC27A6 knockdown in bovine (Bos taurus) mammary epithelial cells (BMECs) was accomplished by RNA interference to further assess the function of SLC27A6. The relative mRNA expression level of genes related to lipid metabolism after SLC27A6 knockdown in BMECs was analyzed by real-time quantitative PCR, and the protein level of SLC27A6 was analyzed by Western blot. The effect of SLC27A6 knockdown on triglyceride (TG) content and FA composition in BMECs were determined.The result showed that the mRNA and protein levels of SLC27A6 were decreased in SLC27A6-Bos-915 group compared with the control group. And knockdown of SLC27A6 dramatically downregulated the mRNA abundance of genes associated with FA activation long-chain acyl-CoA synthetase 4 (ACSL4), fatty acid transporter CD36 and oxidation carnitine palmitoyl transferase 1A (CPT1A), while abundance of genes associated with transcription regulation peroxisome proliferative activated receptor gamma (PPARG), fatty acid binding protein 3 (FABP3), and fatty acid desaturase 2 (FADS2) were upregulated. In addition, SLC27A6 was silenced, the intracellular content of TG and the percentage of oleic acid (C18∶1cis9) and arachidonic acid (C20∶4cis5,8,11,14) were higher, whereas that of palmitic acid (C16∶0) and stearic acid (C18∶0) were lower. Overall, these results could provide strong support for a central role of SLC27A6 in the regulation of lipid metabolism in BMECs, and have an important guiding significance to improving milk quality by breeding programs.
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