DNA polymorphisms in SREBF1 and FASN genes affect fatty acid composition in Korean cattle (Hanwoo)

Sterol regulatory element binding factor 1 (SREBFI) and fatty acid synthase (FASN) genes play an important role in the biosynthesis of fatty acids and cholesterol, and in lipid metabolism. This study used polymorphisms in the intron 5 of bovine SREBF1 and in the thioesterase (TE) domain of FASN genes to evaluate their associations with beef fatty acid composition. A previously identified 84-bp indel (L: insertion/long type and S: deletion/short type) of the SREBFI gene in Korean cattle had significant associations with the concentration of stearic (C18:0), linoleic (C18:2) and polyunsaturated fatty acids (PUFA). The stearic acid concentration was 6.30% lower in the SS than the LL genotype (p<0.05), but the linoleic and PUFA contents were 11.06% and 12.20% higher in SS compared to LL (p<0.05). Based on the sequence analysis, five single nucleotide polymorphisms (SNPs) g.l7924G>A, g. 18043C>T, g. 18440G>A, g. 18529G>A and g. 18663C>T in the TE domain of the FASN gene were identified among the different cattle breeds studied. Among these, only g. 17924 G>A and g.l8663C>T SNPs were segregating in the Hanwoo population. The g.l7924G>A SNP is a non-synonymous mutation (thr2264ala) and was significantly associated with the contents of palmitic (C16:0) and oleic acid (C18:1). The oleic acid concentration was 3.18% and 2.79% higher in Hanwoo with the GG genotype than the AA and AG genotypes, respectively (p<0.05), whereas the GG genotype had 3.8% and 4.01% lower palmitic acid than in those cattle with genotype AA and AG respectively (p<0.05). Tissue expression data showed that SREBFI and FASN genes were expressed in a variety of tissues though they were expressed preferentially in different muscle tissues. In conclusion, the 84-bp indel of SREBFI and g.l7924G>A SNP of the FASN gene can be used as DNA markers to select Hanwoo breeding stock for fatty acid composition.