| PPAR gene family (PPARs) is a group of receptors that regulate the expression of fatty acid and its derivatives, including alpha, beta (or delta) and gamma three subtypes. In poultry, PPARs was found to be related to the subcutaneous fat, fatty liver and immune resistance, and other important economic traits, but the regulation of PPARs in the same biological process showed a difference in function. These differences may be related to the differences in evolution and expression of PPARs. This article carries on the analysis to the PPAR gene family evolutionary divergence, explicating the evolutionary relationships among the members of the, understanding the reason for the differences of the family members. Through the analysis of the structural differences of the PPAR gene family, we selected the active components related to the differential regulation of PPARs, and verified the relationship between the active components and gene expression regulation. By means of these studies, the regulation of duck PPARs gene expression, as well as the mechanism to regulate the formation of important economic traits of PPARs in poultry, lay the foundation for the study. Research results show that:The divergences of PPAR family appeared in fish firstly, followed by birds and mammals. The phylogenetic tree showed ?,? and ? three genotypes of significant differences, including ? and other two subtype differences earlier. Most species have ZnF_C4 and HOLI domains in the amino acid sequence of PPARs. HOLI and the ZnF_C4 domain of Ka/Ks, and the promoter element number, support ? and ? in evolution closer, more primitive ?.We cloned and obtained duck PPAR?, PPAR? and PPAR?, whose promoter fragment length was 2526bp,1631 bp and 2942bp respectively, with the chicken homology were 70%, 71% and 75%. Duck PPARs promoter region contains CAAT-box, TATA-box site, no CpG island.We constructed the duck PPARs members Luciferase report gene vector, which had 7 a and ?,6 ?. At the cell level experiment we screened to duck PPARa gene promoter fragment upstream of -150bp?-66bp and fragment -1059bp?-876bp, and ? fragment upstream of 675bp?-540bp and y upstream fragment -580bp?-360bp have the positive regulatory regions, but ? upstream fragment -1267bp?-1036bp contains the area of negative regulation region. Through the promoter activity region analysis, we screened out a total of 3 transcription factors of PPARs, including NF-1, Sp1 and C/EBPa.The expression pattern of NF-1, Sp1, C/EBP? and PPARs in the skeletal muscle development during embryonic period of duck showed that the 3 transcription factors expressed in the skeletal muscle of duck embryo. Two way cluster analysis showed that there was a high homology between PPAR? and PPAR? at Sp1, and NF-1 had a high homology with PPAR?. NF-1 may be one of the reasons for the functional differences between the PPAR? and the other 2 family members, and Sp1 may lead to differences in function of PPAR? and PPAR?.To sum up, PPAR? is probably the original ancestral gene of PPAR gene family, and the degree of PPAR? gene is the highest in the process of PPAR gene family evolution. The length of PPAR?, PPAR? and PPAR? promoter fragments are 2526bp,1631bp and 2942bp, respectively. Screening to PPAR? gene promoter fragment upstream of -150bp?-66bp and fragment -1059bp?-876bp, and ? fragment upstream of 675bp?-540bp and ? upstream fragment -580bp?-360bp have the positive regulatory regions, but ? upstream fragment-1267bp?-1036bp contains the area of negative regulation region. Each member of PPARs has 3 transcription factors, including NF-1, Sp1 and C/EBP?. There is a high homology between PPAR? and PPAR? at Sp1, and NF-1 has a high homology with PPAR?. NF-1 may be one of the reasons for the functional differences between the PPAR? and the other 2 family members, and Sp1 may lead to differences in function of PPAR? and PPAR?. |
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