Differential tissue expression of porcine IGF-1R, cloning and genetic polymorphisms of the 5′regulatory region.
An analysis of differential mRNA expression levels in respective eleven tissues of exotic and local pig breeds were carried out by using Real-time PCR. To further study the differential expression mechanism of the gene, the 5′regulatory region fragment of IGF-1 gene was amplified by PCR and the primers were designed based on the conserved sequences of the 5′regulatory regions in human being and rodent, and genetic polymorphisms between Landrace × Yorkshire and Dahuabai pigs were studied by PCR-direct sequencing technology. Then, three CpG islands in the 5′regulatory region were predicted by using bioinformatics. The results showed that there was the highest expression levels in hearts in both of the two breeds and no differences in livers between the two breeds. The expression of IGF-1R mRNA were significantly higher in heart, lungs, M. longissimus, brain and cerebellum, pituitary in Landrace × Yorkshire cross than that in Dahuabai, and the folds of its expression levels between the two breeds were 6.06, 52.56, 7.70, 2.43, 3.63 and 41.38, respectively. However, its expression in the stomach, spleen, lung, expression was significantly lower than that in. Dahuabai. The 1 356 bp 5′ regulatory region sequence was obtained and there were not any polymorphisms in this region in the two pig breeds. Three CpG islands, which lengths respective 353 bp, 603 bp and 264 bp, were found in the 5′regulatory region.