The activity of calpains, in particular μ-calpain, is associated with several processes occurring in muscle tissue postmortem and influences meat quality parameters. Therefore, the CAPN1 gene coding for large subunit of μ-calpain is considered as a candidate gene associated with meat quality traits. The aim of our study was to identify new polymorphisms in regulatory regions of the porcine CAPN1 gene and to estimate their impact on CAPN1 transcript abundance. In the present study, 7 polymorphisms in the porcine CAPN1 gene were identified, of which 5 were localized in introns (g.1195_1197insCCT; g.1429G>A; g. [4479A>G; 4526A>T; 4529_4530delAG]), one in 3’ untranslated region (g.25676C>T) and one microsatellite sequence in promoter region (c.-155- AGGG [3_5]). The analysed populations (a total of 451 gilts representing three pure breeds: Pietrain, P lish Landrace, Polish Large White and one conservation breed Pu.awska) were not in Hardy-Weinberg equilibrium according to mutation g.25676C>T in 3’ untranslated region (all breeds), g.1429G>A (Pu.awska pigs) and g. [4479A>G; 4526A>T; 4529_4530delAG] (PLW pigs). Furthermore, the analysed SNPs in the porcine CAPN1 gene were in linkage disequilibrium (P≤0.05). The CAPN1 transcript abundance was also estimated in two important muscles (m. longissimus dorsi, m. semimembranosus). In longissimus dorsi muscle, a significant effect of c.-155- AGGG [3_5] polymorphism in promoter region on CAPN1 expression levels was determined. The c.-155AGGG [3/3] pigs showed a statistically higher (P≤0.05) expression level of the CAPN1 gene when compared to c.-155AGGG [4/4] homozygotes. The results obtained suggested that detected SNPs within regulatory regions of the CAPN1 gene could be related to transcript level and activity of μ-calpain. The selected polymorphisms areproposed to be associated with meat production traits.
