The nuclear factor-κB (NF-κB) signaling pathway plays a crucial role in regulating many physiological processes such as development, inflammation, apoptosis, cell proliferation, differentiation and immune responses. And the NF-κB/Rel family members were considered as the most important transcription factors in the NF-κB signaling pathway. In this study, we cloned a Rel homolog gene (named as CgRel2) from the Pacific oyster, Crassostrea gigas. The 2115-bp open reading frame (ORF) encodes 704 amino acids and CgRel2 possesses a conserved Rel Homology Domain (RHD) at the N-terminus. Phylogenetic analysis revealed that CgRel2 is most closely related to Pinctada fucata dorsal protein. CgRel2 transcripts are widely expressed in all tested tissues, with the highest expression observed in the labial palp and the gill. Moreover, the expression of CgRel2 is significantly upregulated after lipopolysaccharide (LPS), peptidoglycan (PGN), and polyinosinic-polycytidylic acid [poly(I:C)] challenge. CgRel2 transfection into human cell lines activated NF-κB, TNFα and oyster IL-17 (CgIL-17) reporter genes in a dose-dependent manner, while CgRel2 overexpression cannot induce ISRE (Interferon stimulation response element) reporter gene's transcriptional activity. Additionally, the results of co-immunoprecipitation showed that CgRel2 or CgRel1 could interact with oyster IκB1, IκB2 and IκB3 proteins strongly, which may be critical for the immune signaling transduction and the regulation of its immune functions. Together, these results suggest that CgRel2 could respond to pathogenic infection, participate in the immune signal transduction and activate NF-κB, TNFα and CgIL-17 reporter genes. Thus, CgRel2 could play an important role in the oyster immune system.

中文翻译：

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太平洋牡蛎中Rel基因的分子表征和功能分析。

核因子-κB（NF-κB）信号通路在调节许多生理过程（如发育，炎症，凋亡，细胞增殖，分化和免疫反应）中起着至关重要的作用。NF-κB/ Rel家族成员被认为是NF-κB信号通路中最重要的转录因子。在这项研究中，我们从太平洋牡蛎Crassostrea gigas克隆了一个Rel同源基因（名为CgRel2）。2115 bp的开放阅读框（ORF）编码704个氨基酸，CgRel2在N端具有保守的相对同源结构域（RHD）。系统发育分析表明，CgRel2与Pinctada fucata背蛋白关系最密切。CgRel2转录本在所有测试组织中广泛表达，在唇lab和and中观察到最高的表达。此外，脂多糖（LPS），肽聚糖（PGN）和聚肌苷酸-聚胞苷酸[poly（I：C）]攻击后，CgRel2的表达显着上调。CgRel2转染到人细胞系中以剂量依赖的方式激活了NF-κB，TNFα和牡蛎IL-17（CgIL-17）报告基因，而CgRel2过表达不能诱导ISRE（干扰素刺激反应元件）报告基因的转录活性。另外，免疫共沉淀的结果表明，CgRel2或CgRel1可以与牡蛎IκB1，IκB2和IκB3蛋白强烈相互作用，这可能对免疫信号转导及其免疫功能的调节至关重要。总之，这些结果表明CgRel2可以对病原体感染做出反应，参与免疫信号转导并激活NF-κB，TNFα和CgIL-17报告基因。因此，CgRel2可以在牡蛎免疫系统中发挥重要作用。