Novel polymorphisms in the 5′UTR of FASN, GPAM, MC4R and PLIN1 ovine candidate genes: Relationship with gene expression and diet

• We analyzed the 5′cis-regulatory regions of four genes involved in lipid metabolism in sheep.
• We identified 10 novel polymorphisms in the 5′regulatory regions in FASN, GPAM, MC4R and PLIN1 genes.
• The polymorphisms fall into the core sequence of transcription factor binding sites.
• The adipogenic genes are over expressed in the intensive group (ING- GRE and IND).

We have analyzed the 5′cis-regulatory regions of four genes coding for key proteins involved in lipid metabolism and energy homeostasis in Rasa Aragonesa, Assaf and Roja Mallorquina sheep breeds. We identified 10 novel polymorphisms in the 5′regulatory regions in fatty acid synthase (FASN), glycerol-3-phosphate acyltransferase mitochondrial (GPAM), melanocortin-4 receptor (MC4R) and perilipin (PLIN1) genes. Due to the involvement of these genes in fat quantitative traits and the effect of all polymorphic positions on transcription factors binding sites, we tested all of them in two relevant meat reared breeds which were subjected to different feeding systems. Although no relationship was detected between the mRNA expression level of the candidate genes and the genotypes, additional studies must be conducted in older individuals, since these polymorphisms have been detected by in silico studies to be putatively involved in transcriptional or posttranscriptional regulatory mechanisms. The expression level of GPAM, MC4R and PLIN1 genes was analyzed and compared between feeding groups detecting over expression of adipogenic genes in the intensive groups. These results suggest that nutritional stimulation affects the expression of candidates genes involved in lipid metabolic processes, and therefore the fat quality in meat ruminant-derived food products.