tgfβ1a/vegfa gene expression and methylation in response to acute hypoxia in Japanese flounder (Paralichthys olivaceus)

The physiological response and molecular mechanism of the immune response of Japanese flounder under hypoxia stress remain unclear. In this study, we examined the immune-related physiological indexes and the molecular mechanisms of Japanese flounders under acute hypoxia stress. The results showed that the levels of serum ALT, ALP, AST and LDH in hypoxia stress group were significantly increased (P < 0.01). Through quantitative real-time PCR and double in situ hybridization, we found acute hypoxia stress induced immune response of skeletal muscle and gill filaments. The transcriptional regulation mechanism of this immune signaling pathway was investigated by dual luciferase assay. In addition, DNA methylation levels of genes were detected to explore epigenetic modifications of this pathway. As a transcription factor, Foxo1a can interact tgfβ1a(AGATGTTTTTT) and vegfa(TTCTTTTTATA, TACTGTTGCTA) sequences of the promoter regions. The DNA methylation levels of tgfβ1a and vegfa genes were significantly affected by hypoxia and negatively correlated with their expression. These experiments showed that the expression of immune related genes tgfβ1a and vegfa were regulated by transcription factor Foxo1a and DNA methylation. Our study provides theoretical foundations for acute hypoxia stress induced immune response of Japanese flounder.