Effects of Genetic Polymorphism in the Gene on Milk Fat Traits and Relevance to Lipid Metabolism in Bovine Mammary Epithelial Cells.

Milk fat is an important indicator for evaluating milk quality and a symbol of the core competitiveness of the dairy industry. It can be improved through genetic and feed management factors. Interferon alpha-inducible protein 27 () was found to be differentially expressed when comparing the transcriptome in high- and low-fat bovine mammary epithelial cells (bMECs) in our previous research. Therefore, this study aimed to investigate whether the IFI27 gene had a regulatory effect on lipid metabolism.We detected six SNPs in the gene (UTR-(-127) C>A, UTR-(-105) T>A, UTR-(-87) G>A, I1-763 G>T, E2-77 G>A, E2-127 G>T) in a Chinese Holstein cow population. Association analysis of the polymorphism of and milk quality traits showed that the AG and GG genotype of E2-77 G>A, and the GG and TT genotypes of E2-127 G>T were connected to milk fat ( < 0.05). Haplotype frequency analysis showed that H5H5 was associated with lower milk fat content ( < 0.05), while milk from H5H6 animals had a higher fat content ( < 0.05). Subsequently, overexpression vectors (PBI-CMV3-) and interference vectors (Pb7sk-GFP-shRNA) were constructed. Overexpression of the gene in bMECs caused a significant increase in triglycerides (TGs) content ( < 0.05) and decreases in cholesterol (CHOL) and nonestesterified fatty acid (NEFA) content ( < 0.05), while interference with expression produced opposing changes ( < 0.05). In summary, E2-77 G>A and E2-127 G>T may be useful as molecular markers in dairy cattle to measure milk fat, and the gene may play an important role in milk lipid metabolism.