MicroRNA-34介导的NF-κB调节JAK/STAT通路的分子机制

NF-κB and JAK-STAT signaling pathway play a critical role in the regulation of innate immunity. We have identified miR-34 in Pacific white shrimp (Litopenaeus vannamei). Bioinformatics prediction demonstrated that miR-34 could target JAK which is the key components of the JAK/STAT signaling pathway. The transcription of miR-34 was also predicted to be regulated by Dorsal, a member of the NF-κB family in shrimp, and signal transducer and activator of transcriptions (STAT), respectively. In this project, through studying the following issues: identification of miR-34 molecules and its promoter, verification JAK targeted by miR-34, and explain the mechanism of miR-34 transcriptionally regulated by Dorsal and STAT, we revealed a miR-34 mediated mechanism for regulation of the JAK/STAT signaling pathway by NF-κB, analyzed its regulatory effect on shrimp anti-pathogen immunity, and identified its critical role to maintain the immune balance between different immune responses of shrimp. This research can provide an in-depth insight into the immune regulatory mechanism of shrimp, make a theoretical foundation for preventing diseases, and help to further reveal the mutual regulatory mechanism of the invertebrate NF-κB and JAK/STAT signaling pathway.

NF-κB和JAK-STAT通路在先天性免疫调控中发挥关键作用。我们鉴定了凡纳滨对虾的microRNA-34（miR-34）分子，预测其靶向JAK/STAT通路关键信号转导蛋白JAK，且其自身启动子存在Dorsal（NF-κB家族蛋白）和STAT的调控位点。本项目拟通过开展miR-34分子及启动子鉴定、miR-34对JAK基因的表达调控、Dorsal及STAT调控miR-34表达的机制等方面的研究，揭示一种由miR-34介导的对虾NF-κB与JAK/STAT通路之间的调控途径，并进一步解析该调控途径影响对虾抗病免疫的机理，阐明其在对虾不同免疫反应均衡调节过程中的作用。通过本研究能够深入了解对虾免疫系统的调控机制，为病害防治提供理论基础，并有助于进一步揭示无脊椎动物NF-κB和JAK/STAT信号通路的互作机制。

microRNAs是一类进化保守的长约18~26 nt的单链非编码小子RNA，通过与靶标基因mRNA不完全互补结合，在转录后水平抑其表达，广泛参与调控多种生物学过程。NF-κB和JAK-STAT是两条重要的信号通路，在生物体先天性免性调控过程中发挥着关键作。本项目在凡纳滨对虾体内鉴定了miR-34分子，其与人（Homo sapiens）、小鼠（Mus musculus）和果蝇（Drosophila melanogaster ）等生物的miR-34具有高度同源性，并以前体和成熟体的形式广泛存在于对虾各个组织中，在弧菌、WSSV等不同免疫源刺激后，均出现不同水平的上调，表明其在对虾抗病免疫过程中发挥着重要调控作用。靶标鉴定结果显示，miR-34能够靶向抑制JAK的表达，抑制STAT磷酸化形成二聚体进入细胞核，从而激活其下游抗脂多糖因子（ALF）、凝集素（CTL）、溶菌酶（Lys）和抗菌肽（PEN）等免相关基因的转录，进而抑制对虾的抗病毒和抗细菌能力。miR-34转录调控研究结果显示，其启动子中分别存在一个STAT和一个Relish（对虾NF-κB同源蛋白）结合位点，对虾STAT和Relish能分别通过与这两个位点结合，激活miR-34的转录，进而在对虾体内形成了STAT/miR-34/JAK负反馈调节环路，且Relish能够能过该反馈环路，抑制JAK-STAT通路的活性。本项目通过深入解析miR-34的调控和被调控机制，鉴定了由miR-34介导的NF-κB通路调控JAK-STAT通路分子机制，解析了对虾抗细菌和抗病毒通路之间相互调节以均衡分配能源物质并形成动态平衡的生物学过程。本项目有助于深入了解无脊椎动物的免疫调节机理，为对虾病防治提供理论基础。