Cloning and expression analysis of the nuclear factor erythroid 2-related factor 2 (Nrf2) gene of grass carp (Ctenopharyngodon idellus) and the dietary effect of Eucommia ulmoides on gene expression

Abstract

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an important transcription factor in the regulation of redox homeostasis, which plays a vital role in metabolism, the cell cycle, and cell protection. In this study, the complete cDNA sequence of Nrf2 gene of grass carp was obtained by rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR), and the characteristics of Nrf2 proteins predicted from gene sequencing were analyzed by bioinformatics methods. Tissue differential expression patterns were also detected by Real-time Fluorescence quantitative PCR (qRT-PCR). Then, Eucommia ulmoides (EU), a traditional Chinese medicine, was added into diet with an inclusion of 2% to feed grass carp for 3 months to investigate the effects on the expression of Nrf2 gene in tissues. The results showed that the full-length of Nrf2 gene of grass carp is 2760 bp, encoding 593 amino acids, and the predicted Nrf2 protein is a hydrophilic and non-secretory protein. Grass carp Nrf2 gene showed higher expression in kidney, gill, liver, spleen, and blood tissues than in other tissues. In the feeding trial, dietary EU significantly promoted the Nrf2 mRNA expression in kidney, gill, and liver tissues after three months feeding. The results suggest that Nrf2 plays an important role in the anti-oxidative capacity of grass carp and its expression is enhanced by dietary EU.