Molecular cloning and characterization of olive flounder (Paralichthys olivaceus) peroxisome proliferator-activated receptor γ

Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that play key roles in lipid and energy homeostasis. Olive flounder (Paralichthys olivaceus) PPARγ cDNA (olPPARγ) was isolated by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The full-length cDNA is 1667-bp long and encodes a polypeptide with 532 amino acids containing a C4-type zinc finger and a ligand-binding domain. Quantitative RT-PCR revealed that olPPARγ transcription was detected from 7 days post-hatching, and its expression was increased under a starved condition. Overexpression of olPPARγ stimulated PPAR response element (PPRE) activity, and treatment with rosiglitazone, a PPARγ agonist, augmented olPPARγ-stimulated PPRE activity in HINAE olive flounder cells. Cotransfection of olPPARγ and olRXRβ, in the absence or presence of rosiglitazone and ciglitazone, produced a synergistic effect on PPRE transactivation in 3T3L1 adipocytes. Moreover, olPPARγ, in the presence or absence of rosiglitazone, regulated the expression of lipid synthesis- and adipogenesis-related proteins in NIH3T3 and 3T3L1 cells. Taken together, these results suggest that olPPARγ is functionally and evolutionarily conserved in olive flounder and mammals.