Abstract
BackgroundThe ELOVL fatty acid elongase 6 (ELOVL6), the only elongase related to de novo lipogenesis, catalyzes the rate-limiting step in the elongation cycle by controlling the fatty acid balance in mammals. It is located on pig chromosome 8 (SSC8) in a region where a QTL affecting palmitic, and palmitoleic acid composition was previously detected, using an Iberian x Landrace intercross. The main goal of this work was to fine-map the QTL and to evaluate the ELOVL6 gene as a positional candidate gene affecting the percentages of palmitic and palmitoleic fatty acids in pigs.Methodology and Principal FindingsThe combination of a haplotype-based approach and single-marker analysis allowed us to identify the main, associated interval for the QTL, in which the ELOVL6 gene was identified and selected as a positional candidate gene. A polymorphism in the promoter region of ELOVL6, ELOVL6:c.-533C>T, was highly associated with the percentage of palmitic and palmitoleic acids in muscle and backfat. Significant differences in ELOVL6 gene expression were observed in backfat when animals were classified by the ELOVL6:c.-533C>T genotype. Accordingly, animals carrying the allele associated with a decrease in ELOVL6 gene expression presented an increase in C16:0 and C16:1(n-7) fatty acid content and a decrease of elongation activity ratios in muscle and backfat. Furthermore, a SNP genome-wide association study with ELOVL6 relative expression levels in backfat showed the strongest effect on the SSC8 region in which the ELOVL6 gene is located. Finally, different potential genomic regions associated with ELOVL6 gene expression were also identified by GWAS in liver and muscle, suggesting a differential tissue regulation of the ELOVL6 gene.Conclusions and SignificanceOur results suggest ELOVL6 as a potential causal gene for the QTL analyzed and, subsequently, for controlling the overall balance of fatty acid composition in pigs.
Highlights
Food fatty acid (FA) composition is a critical aspect in human health and it is relevant for meat quality
We characterized the porcine ELOVL6 gene and we presented several pieces of evidence confirming that this lipogenic enzyme is highly associated with fatty acid composition in pigs
The characterization of the coding and proximal promoter regions of the porcine ELOVL6 gene allowed for the identification of several mutations, especially the ELOVL6:c.-533C.T polymorphism strongly associated with muscle and backfat percentages of palmitic and palmitoleic acids
Summary
Food fatty acid (FA) composition is a critical aspect in human health and it is relevant for meat quality. It determines important sensorial and technological aspects of meat due to the variability in the melting point of fatty acids. The ELOVL fatty acid elongase 6 (ELOVL6), the only elongase related to de novo lipogenesis, catalyzes the ratelimiting step in the elongation cycle by controlling the fatty acid balance in mammals. It is located on pig chromosome 8 (SSC8) in a region where a QTL affecting palmitic, and palmitoleic acid composition was previously detected, using an Iberian x Landrace intercross. The main goal of this work was to fine-map the QTL and to evaluate the ELOVL6 gene as a positional candidate gene affecting the percentages of palmitic and palmitoleic fatty acids in pigs
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