Tissues Expression, Polymorphisms of IFN Regulatory Factor 6 (IRF6) Gene and Their Associated with Immune Traits in Three Pig Populations

Interferon regulatory factor 6 (IRF6) gene is a member of the IRF-family, and plays functionally diverse roles in the regulation of the immune system. In this report, the 13,720 bp porcine IRF6 genomic DNA structure was firstly identified with a putative IRF6 protein of 467 amino acids. Alignment and phylogenetic analysis of the porcine IRF6 amino acid sequences with their homologies to other species showed high identity (over 96%). Tissues expression of IRF6 mRNA was observed by RT-PCR, the results revealed IRF6 expressed widely in eight tissues. One SNP (HQ026023:1383 G>C) in exon7 and two SNPs (HQ026023:130 G>A; 232 C>T) in the 5 ′ promoter region of porcine IRF6 gene were demonstrated b y DNA sequencing analysis. A further analysis of SNP genotypes associated with immune traits including IFN-γ and IL10 concentrations in serum was carried out in three pig populations including Large White, Landraces and Songliao Black pig (a Chinese indigenous breed). The results showed that the SNP (HQ026023:1383 G>C) was significantly associated with the level of IFN-γ (d 20) in serum (p = 0.038) and the ratio of IFN-γ to IL10 (d 20) in serum (p = 0.041); The other two SNPs (HQ026023:130 G>A; 232 C>T) were highly significantly associated with IL10 level in serum both at the day 20 (p = 0.005; p = 0.001) and the day 35 (p = 0.004; p = 0.006). Identification of the porcine IRF6 gene will help our further understanding of the molecular basis of the IFN regulation pathway in the porcine immune response. All these results should indicate that the IRF6 gene can be regarded as a molecular marker associated with the IL10 level in serum and used for genetic selection in the pig breeding.