Interferons play an important role in the fish innate immune system against viral infection by inducing the interferon stimulated genes, such as Mx gene. We cloned the MxII gene promoter from orange-spotted grouper and found three MxII gene promoters. All of them contained two interferon stimulated response elements (ISREs), and three dinucleotide repeat sequences located at 5' end of ISREs. Interestingly, there is a polymorphic GT repeat element located upstream of these ISREs. The three MxII gene promoters respectively contained 27, 29, and 31 GT repeats, namely EcMx_27, EcMx_29, and EcMx_31. To determine whether GT repeat element influence the MxII gene expression, the MxII gene promoters were subcloned into promoterless reporter plasmid and transfected into grouper kidney (GK) cells. The results showed that a significant induction by poly(I:C) was detected in GK cells transfected with pEcMx_31 (2.65 folds) whereas there was no induction in GK cells transfected with pEcMx_27 and pEcMx_29. However, the significant induction by nervous necrosis virus (NNV) infection was found in GK cells separately transfected with three reporter plasmids. These results suggest that the GT repeat element plays an important role in modulation of MxII gene expression and the induction by poly(I:C) and NNV may be mediated through different signal transduction pathways.

中文翻译：

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GT重复多态性对GK细胞中石斑鱼MxII基因启动子的聚（I：C）诱导的影响。

干扰素通过诱导受干扰素刺激的基因（例如Mx基因）在鱼类先天免疫系统抵抗病毒感染中发挥重要作用。我们从橙色斑点石斑鱼中克隆了MxII基因启动子，发现了三个MxII基因启动子。它们全部包含两个干扰素刺激的应答元件（ISRE），和三个位于ISRE 5'末端的二核苷酸重复序列。有趣的是，在这些ISRE的上游有一个多态的GT重复单元。三个MxII基因启动子分别包含27、29和31个GT重复序列，即EcMx_27，EcMx_29和EcMx_31。为了确定GT重复元件是否影响MxII基因表达，将MxII基因启动子亚克隆到无启动子的报告质粒中，并转染到石斑鱼肾（GK）细胞中。结果表明，在用pEcMx_31转染的GK细胞中检测到了由poly（I：C）引起的显着诱导（2.65倍），而在用pEcMx_27和pEcMx_29转染的GK细胞中没有诱导。但是，在分别用三种报告质粒转染的GK细胞中发现了由神经坏死病毒（NNV）感染引起的显着诱导。这些结果表明，GT重复元件在MxII基因表达的调节中起着重要作用，而poly（I：C）和NNV的诱导可能通过不同的信号转导途径介导。在分别用三种报告质粒转染的GK细胞中发现了神经坏死病毒（NNV）感染的显着诱导作用。这些结果表明，GT重复元件在MxII基因表达的调节中起着重要作用，而poly（I：C）和NNV的诱导可能通过不同的信号转导途径介导。在分别用三种报告质粒转染的GK细胞中发现了神经坏死病毒（NNV）感染的显着诱导作用。这些结果表明，GT重复元件在MxII基因表达的调节中起着重要作用，而poly（I：C）和NNV的诱导可能通过不同的信号转导途径介导。