Microcystin (MC) is a cyclic heptapeptide toxin. Nuclear factor erythocyte 2-related factor 2 (Nrf2) can enhance cellular survival by mediating phase 2 detoxification and antioxidant genes. In this study, CpNrf2 cDNA sequences were cloned from freshwater bivalve Cristaria plicata. The full-length CpNrf2 cDNA sequence was 4259 bp, and its homology was the highest with Mizuhopecten yessoensis, reaching 46%. CpNrf2 transcription levels were examined in all tested tissues, and the highest level was in hepatopancreas from C. plicata. The recombinant protein pET32-CpNrf2 was purified with the content of 1.375 mg/mL. The expression levels of CpNrf2 mRNA were raised in hepatopancreas after MC stimulation. After CpNrf2 knockdown, CpNrf2 mRNA levels were significantly down-regulated after 24 h. Compared with control group, the expression levels of ARE-driven enzymes (CpMnSOD, CpCuZnSOD, CpTRX, CpPrx, CpSe-GPx and Cpsigma-GST) were significantly increased, and those enzyme activities were also significantly up-regulated in MC-stimulated group. However, in CpNrf2-iRNA group, they were significantly down-regulated. The results revealed that Nrf2/ARE pathway is very crucial to protect molluscs from MC.

微囊藻毒素（MC）是一种环状七肽毒素。核因子红细胞2相关因子2（Nrf2）可以通过介导2期排毒和抗氧化剂基因来提高细胞存活率。在这项研究中，CpNrf2 cDNA序列是从淡水双壳C Cristaria plicata克隆的。CpNrf2 cDNA的全长为4259 bp，与Mizuhopecten yessoensis的同源性最高，达到46％。在所有测试的组织中检查了CpNrf2的转录水平，最高的水平是来自C. plicata的肝胰腺。纯化的重组蛋白pET32-CpNrf2的含量为1.375 mg / mL。MC刺激后，肝胰腺中CpNrf2 mRNA的表达水平升高。CpNrf2敲低后，CpNrf2 mRNA水平在24小时后显着下调。与对照组相比，MC刺激组的ARE驱动酶（CpMnSOD，CpCuZnSOD，CpTRX，CpPrx，CpSe-GPx和Cpsigma-GST）的表达水平显着升高，并且这些酶的活性也显着上调。但是，在CpNrf2-iRNA组中，它们显着下调。结果表明，Nrf2 / ARE通路对于保护软体动物免受MC侵害至关重要。