Expression Profiles of IGF-1R Gene and Polymorphisms of its Regulatory Regions in Different Pig Breeds

Insulin like growth factor 1 receptor (IGF-1R) is a candidate gene for growth and carcass traits in regulating animal growth, metabolism and endocrine. It is widely expressed in liver, muscle, bone tissues where the IGF-1R functions as a factor that promotes cell growth. In this study, the protein expression level of IGF-1R gene in liver and muscle tissues of three periods (birth, weaning and adult) of three pig breeds (BamaXiang pigs (BM), Tibetan pigs (TM) and Junmu No.1 pigs (JM)) were tested by western blot. SNPs within the regulatory region of pig IGF-1R gene were detected using direct sequencing and then the genotypes were identified through AS-PCR approach. Results showed expression profiles of IGF-1R gene between liver and muscle tissues were different and significant differences were also found among pig breeds. In the same time, four SNPs were detected in the regulatory region of IGF-1R gene, among which the genotype frequency of three (g.-1468G > C, g.-1192 C > T and g.330,424 C > T) were significantly different among the pig breeds. BM tended to heterozygous (GC/CT) of the anterior two loci, while TM and JM preferred the other two homozygotes respectively. For the g.330,424 C > T, all pig breeds were tended to be the heterozygous. In conclusion, the SNPs with different genotype distribution among the three pig breeds may explain the gene expression difference between the different pig breeds.