A Functional Variant in the Stearoyl-CoA Desaturase Gene Promoter Enhances Fatty Acid Desaturation in Pork

Abstract

There is growing public concern about reducing saturated fat intake. Stearoyl-CoA desaturase (SCD) is the lipogenic enzyme responsible for the biosynthesis of oleic acid (18∶1) by desaturating stearic acid (18∶0). Here we describe a total of 18 mutations in the promoter and 3′ non-coding region of the pig SCD gene and provide evidence that allele T at AY487830:g.2228T>C in the promoter region enhances fat desaturation (the ratio 18∶1/18∶0 in muscle increases from 3.78 to 4.43 in opposite homozygotes) without affecting fat content (18∶0+18∶1, intramuscular fat content, and backfat thickness). No mutations that could affect the functionality of the protein were found in the coding region. First, we proved in a purebred Duroc line that the C-T-A haplotype of the 3 single nucleotide polymorphisms (SNPs) (g.2108C>T; g.2228T>C; g.2281A>G) of the promoter region was additively associated to enhanced 18∶1/18∶0 both in muscle and subcutaneous fat, but not in liver. We show that this association was consistent over a 10-year period of overlapping generations and, in line with these results, that the C-T-A haplotype displayed greater SCD mRNA expression in muscle. The effect of this haplotype was validated both internally, by comparing opposite homozygote siblings, and externally, by using experimental Duroc-based crossbreds. Second, the g.2281A>G and the g.2108C>T SNPs were excluded as causative mutations using new and previously published data, restricting the causality to g.2228T>C SNP, the last source of genetic variation within the haplotype. This mutation is positioned in the core sequence of several putative transcription factor binding sites, so that there are several plausible mechanisms by which allele T enhances 18∶1/18∶0 and, consequently, the proportion of monounsaturated to saturated fat.

A polymorphism in the stearoyl-CoA desaturase gene promoter influences monounsaturated fatty acid content of Duroc × Iberian hams

“…ness and juiciness (Ruiz-Carrascal et al, 2000). In this study the SCD genotype did not affect fat content, in agreement with what has been reported in Estany et al (2014) for IMF in three distinct raw muscles. Similarly, the fat content was not affected by the gender, which is in accordance with what has been observed by some authors using Duroc × Iberian crossbred barrows and castrated and intact females (Serrano et al, 2008;Cordero et al, 2010), but not all.…”

“…The substitution of MUFA for PUFA is a side effect that indirectly may benefit the quality of the ham, since it is known that PUFA increase susceptibility to oxidative processes and off-flavors . The substitution effect of the T allele for C18:1n-9 and MUFA (0.69% and 0.95%) was very close to the values obtained by Estany et al (2014) for C18:1 (C18:1n-9+C18:1n-7, 0.70%) and MUFA (1.02%), thereby confirming that the favorable effect of the T allele on fat desaturation observed in purebred Duroc raw muscles is maintained in Duroc × Iberian dry-cured hams. The favorable effect of allele T on MUFA in Duroc × Iberian had already been reported in raw muscle .…”

“…The single nucleotide polymorphism AY487830: g.2228T>C, which was selected as a tag SNP to evaluate the effect of alternate haplotypes, was genotyped using an allelic discrimination assay with the primers and probes indicated in Estany et al (2014). The reaction mix contained 1x Universal TaqMan master mix acid content is positively correlated with pork flavor, flavor liking and overall acceptability (Cameron et al, 2000;Tikk et al, 2007).…”

“…A relevant part of the variation in MUFA and oleic acid has a genetic origin and thus can be attributed to differences between breeds (Wood et al, 2004;Reixach et al, 2008) and individuals within breed (Ros-Freixedes et al, 2012). A recent research of Estany et al (2014) has shown that a haplotype in the promoter region of the stearoyl-CoA desaturase (SCD) gene, which enhances fat desaturation and, as a result, MUFA and oleic acid in muscle and subcutaneous fat, segregates in Duroc. This beneficial effect is maintained in purebred dry-cured Duroc hams (Henriquez-Rodriguez et al, 2015), despite the fatty acid compositional changes occurring through lipolysis and oxidation in the curing process (Narváez-Rivas et al, 2008;Gandemer, 2009).…”

A WUR SNP is associated with European Porcine Reproductive and Respiratory Virus Syndrome resistance and growth performance in pigs

“…Briefly, the data set included 617 Duroc and 53 LW × LS commercial pigs with data on live body weight at 80, 160, 180, and 205 days used for other studies (Estany et al, 2014). Pigs were from nine different batches raised in PRRSV negative farms.…”