The pig p160 co-activator family: Full length cDNA cloning, expression and effects on intramuscular fat content in Longissimus Dorsi muscle

Evidence has shown in mouse that the p160 co-activator family, consisting of nuclear receptor co-activators 1 (NCOA1), 2 (NCOA2) and 3 (NCOA3) plays a critical role in adipogenesis. In the present study, we cloned these three porcine genes, identified their transcript variants and analyzed their expression level in relation to intramuscular fat (IMF) content in Longissimus Dorsi (LD) muscle. Both in silico cloning and PCR amplification revealed a full length cDNA sequence of 6591 bp for NCOA1 (EU346671), 7628 bp for NCOA2 (EU346672) and 5005 bp for NCOA3 (EU346674) in pigs, respectively. Interestingly, three transcript variants were identified for the porcine NCOA1 and two for the porcine NCOA2 gene. In addition, the deduced amino acid sequences indicated that isoform 2 of NCOA2 lacks the fourth LXXLL motif, the number of which has been shown to influence the selectivity and affinity for different nuclear receptors. Finally, 15 animals with high IMF content and fifteen animals with low IMF content (p < 0.05) selected from 60 individuals were used to investigate how the family members and their variants affect the phenotype in pigs using real-time PCR. Our results showed that both NCOA1 transcript variant 2 (r = −0.554, p < 0.01) and total NCOA1 (r = −0.516, p < 0.01) expression levels were negatively correlated with IMF contents, while NCOA2 transcript variant 1 (r = 0.605, p < 0.01) and NCOA3 (r = 0.435, p < 0.05) were positively associated with IMF content in LD muscle. Overall, the present study provides evidence for the first time that the p160 co-activator family might have a concordant effect on lipid metabolism in mammals.