The Nrf2 (nuclear factor erythroid 2-related factor 2) plays a central role in cell protection against a wide variety of environmental stressors through the Nrf2-Keap1 (Kelch-like ECH-associated protein 1) pathway, but its involvement in modulation of antioxidant system of fish cell is still largely unexplored. The present study focused on the molecular cloning and silencing of the Nrf2 in the fathead minnow muscle cell line (FHM) in response to the oxidative stress induced by H₂O₂. A full-length cDNA of coding Nrf2 was cloned from FHM cells by RT-PCR and RACE approaches. The obtained cDNA covered 2578 bp with an open reading frame (1770 bp) of encoding 589 amino acids. Sequence alignment and phylogenetic analysis revealed a high degree of conservation (51–86%) among 16 fishes. Based on the cloned Nrf2 sequence, the siRNA-242 of targeting Nrf2 with the best knocking down efficiency was designed and detected. Then, the mRNA levels of Keap1, Nrf2, Maf (musculoaponeurotic fibrosarcoma oncogene), and HO-1 (haemoxygenase-1); the activities of T-SOD (total superoxide dismutase), CAT (catalase), and GSH-PX (glutathione peroxidase); the levels of GSH (glutathione) and MDA (malonaldehyde); and the cell cycle and apoptosis were analyzed to investigate the molecular responses after H₂O₂ exposure. These results showed a coordinated transcriptional regulation of Keap1, Maf, and HO-1 and antioxidants (T-SOD, GSH, CAT, and GSH-PX) and MDA levels after H₂O₂ exposure, leading to oxidative damage and apoptosis. These findings provided an insight to understand the mechanisms of Nrf2 against oxidative stress in fish.

该Nrf2的（核因子红系2相关因子2）起到了保护细胞抵抗多种通过的Nrf2 Keap1的环境压力的重要作用（KELCH样ECH相关蛋白1）途径，但其抗氧化的调制参与鱼细胞的系统仍未开发。本研究的重点是响应H ₂ O ₂诱导的氧化应激，在黑头min鱼肌肉细胞系（FHM）中Nrf2的分子克隆和沉默。编码Nrf2的全长cDNA通过RT-PCR和RACE方法从FHM细胞中克隆了H.P.R。获得的cDNA覆盖了2578 bp，具有一个编码589个氨基酸的开放阅读框（1770 bp）。序列比对和系统发育分析表明，在16条鱼中具有高度的保守性（51–86％）。基于克隆的Nrf2序列，设计并检测了具有最佳击倒效率的靶向Nrf2的siRNA-242 。然后，Keap1，Nrf2，Maf（肌腱膜纤维肉瘤癌基因）和HO-1的mRNA水平（haemoxygenase-1）；T-SOD（总超氧化物歧化酶），CAT（过氧化氢酶）和GSH-PX（谷胱甘肽过氧化物酶）的活性；GSH（谷胱甘肽）和MDA（丙二醛）的水平；并分析细胞周期和凋亡，以研究H ₂ O ₂暴露后的分子反应。这些结果表明，在暴露于H ₂ O ₂之后，Keap1，Maf和HO-1和抗氧化剂（T-SOD，GSH，CAT和GSH-PX）和MDA的转录调控协调一致，从而导致氧化损伤和细胞凋亡。这些发现为了解Nrf2抗鱼氧化应激的机制提供了见识。