Expression analysis of candidate genes for fatty acid composition in adipose tissue and identification of regulatory regions

The aim of this work was to study the genetic basis of the backfat expression of lipid-related genes associated with meat quality traits in pigs. We performed a genome-wide association study with the backfat gene expression measured in 44 genes by qPCR and the PorcineSNP60 BeadChip genotypes in 115 Iberian x Landrace backcross animals. A total of 193 expression-associated SNPs located in 19 chromosomal regions were associated with expression levels of ACSM5, ELOVL6, FABP4, FADS2, and SLC27A4 genes. Three expression quantitative trail loci (eQTLs) corresponding to ACSM5, FABP4, and FADS2 were classified as cis-acting eQTLs, whereas the remaining 16 eQTLs have trans-regulatory effects. Remarkably, a SNP in the ACSM5 promoter region and a SNP in the 3′UTR region of FABP4 were the most associated polymorphisms with the ACSM5 and FABP4 expression levels, respectively. Moreover, relevant lipid-related genes mapped in the trans-eQTLs regions associated with the ACSM5, FABP4, FADS2, and SLC27A4 genes. Interestingly, a trans-eQTL hotspot on SSC13 regulating the gene expression of ELOVL6, ELOLV5, and SCD, three important genes implicated in the elongation and desaturation of fatty acids, was identified. These findings provide new data to further understand the functional regulatory mechanisms implicated in the variation of fatty acid composition in pigs.This work has been funded by the MINECO AGL2014-56369-C2-R and AGL2017-82641-R grants. MR was funded by a Formació i Contractació de Personal Investigador Novell (FI-DGR) PhD grant from Generalitat de Catalunya (ECO/1639/2013). MB was financially supported by a Ramon y Cajal contract (RYC-2013-12573) from the Spanish Ministry of Economy and Competitiveness, APO was funded by a Personal Investigador en Formación (PIF) PhD grant from the Universitat Autònoma de Barcelona (458-01-1/2011), DCP by a Formació i Contractació de Personal Investigador Novell (FI-DGR) PhD grant from Generalitat de Catalunya (ECO/1788/2014) and LCM was funded by a FPI PhD grant from the Spanish Ministry of Economy and Competitiveness (BES-2015-075403). Funded by grant INIA CPE03-010-C3. We acknowledge financial support from the “Severo Ochoa Programme for Centres of Excellence in R&D” 2016-2019 (SEV‐2015‐0533) and the CERCA Programme / Generalitat de Catalunya.Peer reviewe