Molecular characterization and functional analysis of PPARα promoter in yellow catfish Pelteobagrus fulvidraco

Peroxisome proliferator-activated receptor α (PPARα) is a ligand-activated transcription factor that plays critical roles in the regulation of many important physiological processes. In the present study, the 1686-bp PPARα promoter for yellow catfish Pelteobagrus fulvidraco was first cloned and characterized. The transcription start site (TSS) of PPARα gene was mapped using RLM-5'RACE method. The luciferase vectors were constructed and transiently transfected into HepG₂ cells and HEK293 cells, respectively, for functional analysis of promoters. Bioinformatics analysis revealed the putative core promoter regions including a TATA-box and a CAAT-box located at -35bp and -75bp upstream of the TSS, respectively. A cluster of putative binding sites of several transcription factors, such as AP1, C₂H₂ZFP, E-box, HNF4α, NF-κB, PPAR, Sp1 and STAT1, were identified. Deletion analysis indicated that these transcriptional factor binding sites were essential to the basal promoter activity. Subsequent mutation analysis showed that the PPARα promoter activity was down-regulated following mutation of the TFBSs including NF-κB, PPAR and HNF4α, indicating that these TFBSs were responsible for PPARα activation. Furthermore, the transcription activity of the PPARα promoter was increased and PPARα mRNA expression was up-regulated after fenofibrate treatment. Overall, the present study provided new insights into the mechanisms for transcriptional regulation of PPARα in fish.