Comparative proteomic study of muscle tissue of wild boars and domestic pig breeds.

In the modern conditions, there is a growing consumer interest in products from local (autochthonous) breeds of animals raised in extensive animal husbandry systems. Meat of such animals is often associated with high quality characteristics; however, its molecular foundations remain to be studied insufficiently. Comparative analysis of proteomic profiles of such breeds and their wild ancestor — wild boar — is of particular interest for understanding the fundamental consequences of domestication and selection as well as for revealing key marker proteins determining meat product properties. A comparative proteomic analysis of muscle tissue (M. longissimus dorsi) of wild boar and four pig breeds (Livny breed, Altai meat-type breed, Landrace, Mangalitsa) was carried out to reveal breed-specific molecular patterns associated with key meat quality characteristics. Proteomic profile was studied by two-dimensional electrophoresis (2-DE) and mass spectrometry (MALDI-TOF/TOF). Functional analysis of protein-protein interactions and gene ontology (GO) enrichment were carried out using the STRING database. Twenty one proteins forming a functionally linked network were identified. Significant breed related differences in the composition and modifications of proteins of the contractile apparatus (products of MYL1, MYL2, MYL3, MYL6B, TNNT3, TNNI2 genes), energy metabolism (products of ENO3, ALDOA, CKM, AK1, ATP5F1A genes) and stress response (products of CRYAB, HSPB6 genes) were revealed. The highest degree of proteome transformation was noticed in the Livny breed, which demonstrated a significant similarity with wild boar in terms of several parameters including appearance of atypical myosin light chain MYL6B and a decrease in the level of muscle enolase (products of ENO3 gene). For Mangalitsa, a unique modification of the pattern of expression of myosin light chains and a significant increase in the level of small chaperons were characteristic, which correlates with the conditions of its free-range keeping. Bioinformatics analysis in STRING corroborated statistically significant formation of functional clusters responsible for muscle contraction, metabolism and maintenance of proteostasis. The data obtained suggest that both gene pool (breed) and environmental factors (keeping conditions) exert a complex effect on the proteomic landscape. The revealed protein signatures and their network interactions not only deepen the understanding of the biological foundations of meat quality but also open new prospects for the development of molecular markers in breeding and meat industry aimed at production of products with target properties.