Structural and functional characterization of turbot pparγ: Activation during high temperature and regulation of lipid metabolism

Transcription factors of the peroxisome proliferator-activated receptor gamma (ppar gamma) is a ligand-activated receptor that plays key roles in lipid metabolism and inflammation. In this study, we cloned the ppar gamma cDNA of turbot (Scophthalmus maximus). It has a 1659 bp coding sequence (CDS) and encodes 552 amino acids. The deduced PPAR gamma protein of turbot contains two highly conserved domains, a C4-type zinc finger, a nuclear hormone receptor DNA-binding region signature, and a HOLI domain (ligand-binding domain of hormone receptors) identical to that of in other species. qPCR results showed that the expression level of ppar gamma and the expression of the fatty acid transporters fatp and cd36 were significantly increased under high-temperature stress. This indicates that high temperatures activate the transcriptional activity of ppar gamma, and lipid metabolism plays an important role in turbot under high-temperature stress. In addition, RNA interference was used to explore the regulation of ppar gamma on lipid metabolism of turbot at high temperatures. The results showed that the mRNA level of ppar gamma was significantly decreased. After the expression level of ppar gamma was inhibited, the expression levels of fatp and cd36 were significantly decreased. At the same time, GW9662 (a ppar gamma antagonist) was used to inhibit ppar gamma activity in turbot kidney cells, and fatp and cd36 gene expressions were detected. The mRNA expression levels of ppar gamma, fatp, and cd36 were significantly decreased. Our results suggest that high temperatures activate ppar gamma in turbot and that ppar gamma regulates lipid transport and maintains lipid metabolism homeostasis through positive regulation of the expression of downstream genes fatp and cd36. This study further elucidates that the ppar gamma- mediated signaling pathway may play an important role in regulating lipid metabolism during heat stress in teleost fish.

Automated summary

This study cloned the ppar gamma gene of turbot and found that ppar gamma transcriptional activity was enhanced under high-temperature stress, indicating its important role in lipid metabolism during turbot's adaptation to high temperatures. RNA interference experiments demonstrated that ppar gamma regulates lipid metabolism by positively regulating the expression of downstream genes fatp and cd36. This study further deepens our understanding of the role of the ppar gamma-mediated signaling pathway in regulating lipid metabolism during heat stress in fish.