Immunomodulatory Effects of SPHK1 and Its Interaction with TFAP2A in Yellow Drum ().

Sphingosine kinases (SPHKs) are essential enzymes that catalyze the phosphorylation of sphingosine to produce sphingosine-1-phosphate (S1P), which plays pivotal roles in inflammation and immune regulation. In this study, genome-wide association analysis (GWAS) identified the gene as closely associated with the resistance of yellow drum () to . Structural prediction showed that YDSPHK1 contains a typical diacylglycerol kinase catalytic (DAGKc) domain (154-291 aa). By constructing and transfecting expression plasmids into yellow drum kidney cells, we found that YDSPHK1 is localized in the cytoplasm. Subsequent RNA-Seq analysis of an overexpression plasmid identified 25 differentially expressed genes (DEGs), including 13 upregulated and 12 downregulated. Notably, and were significantly upregulated, while and were downregulated. Promoter analysis indicated that the core regulatory regions of are located between -1931-1679 bp and -419+92 bp, with two predicted TFAP2A binding sites in the -419~+92 bp region. Further studies demonstrated that varying concentrations of TFAP2A significantly reduced promoter activity. These findings underscore the pivotal role of in regulating immune responses in yellow drum, particularly through its impact on key immune-related genes and pathways such as NF-κB signaling and ferroptosis. The identification of as a mediator of immune regulation provides valuable insights into the molecular mechanisms of immune defense and highlights its potential as a target for enhancing pathogen resistance in aquaculture practices. This study lays a strong foundation for future research aimed at developing innovative strategies for disease management in aquaculture species.