Molecular Cloning, Tissue Expression Analysis And Agonist-induced Activation Of Peroxisome Proliferator-activated Receptor (PPAR) Genes In Grass Carp(Ctenopharyngodon Idellus)

Peroxisome proliferator activated receptor (PPAR) is a member of the family of nuclear hormone receptors and there are three isotypes:PPARα, PPAR P and PPAR y. PPAR has many biological effects, such as it can regulate the various genes involved in lipid metabolism. And the research on PPAR will help reveal the rule and its mechanism about the use of nutrients of the herbivorous fish. Eventually used in aquaculture, could regulate the metabolic balance of nutrients in grass carp cultivation, reduce lipid depositions to improve the quality of the meat. We cloned and analysed the cDNA fragments of PPARα, PPARβand PPARγfrom the liver of grass carp. Investigate the tissue distribution patterns of PPARs in liver, brain, spleen, muscle, fat and heart of grass carp. Finally grass carp were intraperitoneally injected with different concentrations of clofibrate,2-bromo palmitate and 15-deoxy-Δ12,14 prostaglandin J2 (15d-PGJ2), respectively. And the relative changes of the mRNA abundance of PPARs in liver, fat and muscle were analyzed by real-time PCR, to investigate the ligand specificities of PPARs in grass carp. The cloned grass carp PPARα, PPARβand PPARγcDNAs were 631bp,604bp and 1331bp in length, encoding 210,201 and 337 amino acids, respectively. Search results revealed that the deduced amino acid sequences of grass carp PPARs were highly (65.0%-96.1%) homologous with mammals, amphibians and other Species of fish. The tissue distribution patterns result suggested that the mRNA constitutive expression level of PPARa predominated in liver, but was weak in other tested tissues. PPARβwas present in all tested organs, and was relative abundant in heart, liver, and muscle. PPARγwas only detected in liver and, to a lesser extent, in brain, muscle and lipid. Ultimately, the results indicate that clofibrate,2-bromo palmitate and 15d-PGJ2 could be applied as the activators of grass carp PPARs.50 mg kg-1 body weight (bwt) dose of clofibrate was able to increase the expression of both PPARαandβ, but was not able to for PPARγ.42 mg kg-1 body weight (bwt) dose of 2-bromo palmitate could affect the expression of both PPARβandγ, but was not able to for PPARα.1 mg kg-1 body weight (bwt) dose of 15d-PGJ2 was able to induce PPARβexpression, but PPARa and y were not enhanced.