Adipose tissue transcriptome profiles of local Krškopolje pig and modern hybrids receiving reduced protein diets

Compared to lean pig genotypes, the local Krškopolje pig is characterised by a greater capacity for lipid and lower capacity for protein deposition, along with lower dietary protein requirements. The aim of the present study was to unravel the transcriptomic differences in subcutaneous adipose tissue between the local Krškopolje pig and modern hybrids, as well as to study the impact of the reduced protein diet in both genotypes. Differential gene expression analysis between local and modern pigs revealed 375 differentially expressed genes, with 189 upregulated and 186 downregulated in Krškopolje pig. Among the upregulated genes, several suggested more pronounced adipogenesis (SLC7A10, ADIRF, INHBB, and SFRP2) in the Krškopolje pig. In addition, genes encoding collagen proteins and extracellular matrix remodelling (e.g., COL6A5, COL4A5, COL2A1), calcium signalling (TRPV4, CAMK2A, CALML5), pro-inflammatory cytokines (e.g., IL1A, TNFSF9, CXCL8, PTGS2 etc.) and cholesterol metabolism (CYP1A1, CYP2A19, CES1 etc.) were differentially expressed. The reduced protein diet induced only minor changes in gene expression at the individual gene level. However, gene set enrichment analysis revealed that, in Krškopolje pigs, dietary effects were associated with biological processes related to immune response, intracellular protein transport, and extracellular matrix organisation. In the case of modern hybrids, a reduced protein diet resulted in enrichment of gene sets related to oxidative phosphorylation, mitochondrial function, and energy metabolism. In conclusion, this study demonstrated that the adipose tissue of Krškopolje pigs compared with modern hybrids exhibited greater adipogenic potential, being also supported by higher expression of genes involved in extracellular matrix remodelling and inflammation. The impact of a reduced protein diet on adipose-tissue gene expression was relatively small in both breeds, particularly in Krškopolje pig, suggesting a metabolic adaptability of this breed.