Comparative transcriptomic analysis of dorsal subcutaneous fat from Portuguese local pig breeds

Abstract

Portuguese local Alentejano (AL) and Bísaro (BI) pig breeds have a higher potential for subcutaneous and intramuscular fat (IMF) deposition than modern lean-type breeds. AL pig belongs to the Iberian branch, presenting many of the characteristics of this group such as a low growth rate, a precociously high adipogenic activity and a high level of unsaturated fatty acids (FA). BI pig is related to the Celtic group, sharing ancestors with breeds such as Large White and Landrace, and generally presents a poor but higher growth than AL, a reasonable amount of IMF and a good unsaturated/saturated FA ratio. Set within the framework of the TREASURE project, this work intended to explore the genetic diversity of AL and BI pig breeds to help better understanding the underlying physiological mechanisms associated with body fat accretion and lean muscle tissue deposition and therefore, meat quality of these breeds. Dorsal subcutaneous fat (DSF) samples were collected from adult AL and BI pigs with ~150kg body weight at slaughter. Total RNA was obtained and sequenced for transcriptome analysis. A total of 375 genes were found to be differentially expressed (DE) in DSF samples (q<0.05). 335 DE genes were overexpressed in AL (|FC|=0.81 to 6.47) and 40 in BI (|FC|=0.91 to 7.11). Preliminary results also demonstrate that genes related to lipid metabolism such as ACACA, FASN, SCD, LEP and ME1 are significantly overexpressed in AL when compared with BI which agrees with the higher lipid content of the AL breed. A functional enrichment analysis (metabolic pathways and GO enrichment) was performed of the DE genes, which showed that the main involved functions include lipid metabolism (synthesis of lipids and release of FA), inflammatory response, amino acid and carbohydrate metabolism. Potential regulators such as MYD88, IL1, IL15, NR1D1 and PPARGC1A were also able to be predicted for these functions.