Abstract
The bulk of body fat in mammals is in the form of triacylglycerol. Diacylglycerol O-acyltransferase 2 (DGAT2) catalyses the terminal step in triacylglycerol synthesis. The proximity of DGAT2 with stearoyl-CoA desaturase (SCD) in the endoplasmic reticulum may facilitate provision of de novo SCD-mediated fatty acids as substrate for DGAT2. Here, we first searched for sequence variants in the DGAT2 gene to then validate their effect on fat content and fatty acid composition in muscle, subcutaneous fat and liver of 1129 Duroc pigs. A single nucleotide polymorphism in exon 9 (ss7315407085 G > A) was selected as a tag variant for the 33 sequence variants identified in the DGAT2 region. The DGAT2-G allele increased DGAT2 expression in muscle and had a positive impact on muscular C14 and C16 fatty acids at the expense of C18 fatty acids. Although there was no evidence for an interaction of DGAT2 with functional SCD genotypes, pigs carrying the DGAT2-G allele had proportionally more palmitoleic acid relative to palmitic acid. Our findings indicate that DGAT2 preferentially uptakes shorter rather than longer-chain fatty acids as substrate, especially if they are monounsaturated, and confirm that fatty acid metabolism in pigs is subjected to subtle tissue-specific genetic regulatory mechanisms.
Highlights
Meat fat content and composition are important attributes that contribute to the nutritional quality and the consumer perception of meat products
Recent findings indicate that Diacylglycerol O-acyltransferase 2 (DGAT2) is engaged in de novo lipogenesis by favouring both the synthesis of TG from glycerol 3-phosphate and the incorporation of endogenous fatty acids into TG, the monounsaturated fatty acids (MUFA) that result from the desaturation of palmitate (C16:0) and stearate (C18:0) through the action of stearoyl-CoA desaturase (SCD)[19]
A sequence variant in the porcine DGAT2 influences muscular gene expression and fatty acid composition, with changes mostly limited to swapping C18 fatty acids for C14 and C16 fatty acids of the same degree of saturation
Summary
Meat fat content and composition are important attributes that contribute to the nutritional quality and the consumer perception of meat products. As a result of a genome-wide association study (GWAS) for fatty acid composition in Duroc pigs, we found that the region on SSC9 where DGAT2 lies was associated with MUFA content Using this Duroc line as a model, we investigate the role of DGAT2 variants on fat metabolism in pigs. We first searched for sequence variants in the promoter, coding, and 3′-untranslated regions of porcine DGAT2 and validated their effect on fat content and composition using data and samples from a large biorepository[23] Given that this line segregates for a functional variant in the SCD gene[24], potential interactions of DGAT2 with SCD were assessed
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