The Functional SNPs in the 5' Regulatory Region of the Porcine PPARd Gene have Significant Association with Fat Deposition Traits

Peroxisome proliferator-activated receptor delta (PPARδ) is a key regulator of lipid metabolism, insulin sensitivity, cell proliferation and differentiation. In this study, we identified two SNPs (-655A/G and -652T/C）in the 5’ regulatory region of porcine PPARδ gene with four haplotypes (GT, GC, AC and AT). Functional analysis of the four haplotypes showed that the transcriptional activity of the PPARδ promoter fragment carrying haplotype AC was significantly lower than that of the other haplotypes in 3T3-L1, C2C12 and PK-15 cells, and haplotype AC had the lowest binding capacities to the nuclear extracts. Transcription factor 7-like 2 (TCF7L2) could improve the transcription activities of promoter fragments of PPARδ gene carrying haplotypes GT, GC and AT in C2C12 and 3T3-L1 cells, and increase the protein expression of PPARδ gene in C2C12 myoblasts. TCF7L2 could differentially bind to the four haplotypes, and the binding capacity of TCF7L2 to haplotype AC was the lowest. There were significant associations between 655A/G and fat deposition traits in three pig populations including the Large White × Meishan F₂ pigs, France and American Large White pigs. These results strongly supported the SNPs in 5’ regulatory region of PPARδ genes had significant effects on pig fat deposition traits.