Molecular characterization and transcriptional regulation between PPAR and CPT1 in freshwater bivalve Hyriopsis cumingii.

Peroxisome proliferator activated receptors (PPARs) exert their roles in lipid metabolism and adaptive immunity by transactivating carnitine palmitoyltransferase 1 (CPT1). However, it remains unclear whether the PPAR-CPT1 signaling pathway exists in mollusks that only carry out innate immunity. This study cloned and characterized PPAR and CPT1 genes from Hyriopsis cumingii for the first time, designated as HcPPARs and HcCPT1s, respectively. The bioinformatics analysis revealed conservative molecular characteristics of these genes across species. Real-time quantitative PCR results indicated that higher expression levels of HcPPARs and HcCPT1s in the blood, mantle, and intestine suggested their potential involvement in lipid metabolism and innate immunity of mollusks. Treatments with agonists and inhibitors demonstrated a correlation in the expression of HcPPARs and HcCPT1s. Dual luciferase reporter assay identified regions with high transcriptional activities on promoters of HcCPT1s and potential binding sites for HcPPARs through prediction and mutation sites. These results suggested that the PPAR-CPT1 signaling might exist in H. cumingii. This research provides a necessary foundation for exploring the role of the PPAR-CPT1 signaling in innate immunity, and offers new theoretical evidence for the molecular regulatory mechanism of mollusks and the treatment of metabolic disorders and inflammatory diseases.