Immune regulatory role of N-Myc and STAT Interactor (Nmi) and its interaction with the N protein of Siniperca chuatsi rhabdovirus in regulating interferon expression
干扰素（interferon，IFN）是一类具有抗病毒、抗细菌和免疫调节等多种功能的细胞因子。根据其分子结构、受体、信号通路以及生物学功能等，脊椎动物IFNs被分为I型、II型、III型和IV型。鱼类属于低等脊椎动物，是脊椎动物中种类最多的一个类群，也是最早拥有完善且复杂IFN系统的脊椎动物，是研究IFN系统组成、功能和演化的重要对象。根据系统发育关系，鱼类I型IFNs被分成8个亚群，分别为IFNa – IFNf以及IFNh和IFNi。不同亚群可选择性利用不同的受体复合物，通过保守的JAK/STAT信号通路诱导干扰素诱导基因（interferon stimulated genes, ISGs）的表达，从而发挥抗病毒等功能。鱼类II型IFNs有2个成员，即IFN-γ和IFN-γrel，它们可分别利用CRFB13/CRFB6和CRFB17受体，通过STAT1传递信号。目前，在硬骨鱼类中还未鉴定到III型IFNs，但软骨鱼类中已鉴定到了III型IFNs及其受体亚基。IV型IFN是我国学者近期在鱼类和原始哺乳动物中鉴定到的一类新IFN基因，具有显著的抗病毒功能，受体由CRFB12和CRFB4组成。本文从基因结构、分类和命名、受体组成、信号传导以及生物学功能等方面总结了鱼类的I型、II型、III型和IV型IFNs的最新研究进展，重点介绍了我国学者在鱼类IFN系统的组成与命名、受体与信号传导、晶体结构、功能、新型IFN等方面所取得的研究成绩。本文不仅为今后鱼类IFN系统的研究提供了可能的方向，也能增强我们对鱼类IFN研究进展的系统性认识，同时也为IFN在鱼类抗病毒和抗细菌感染中的应用提供参考。
Interferons (IFNs) are a class of cytokines with pleiotropic immunological and biological functions, such as antiviral, antibacterial and immunomodulatory functions. In vertebrates, IFNs play pivotal roles in innate immune system, and can also coordinate effective adaptive immunity. Up to now, four types of IFNs, i.e., type I, type II, type III and type IV IFNs, have been reported in vertebrates. As a diversified lineage of vertebrates, fish represents the earliest group of vertebrates to possess well-defined and complicated IFN systems, and they are considered as important for the study of composition, function, and evolution of IFN systems. According to phylogenetic relationships, fish type I IFNs are classified into eight subgroups, namely IFNa - IFNf, IFNh and IFNi, which selectively use different receptor complexes to induce the production of interferon stimulated genes (ISGs) through the conserved JAK/STAT signaling pathway, thereby exerting their biological functions, such as antiviral and antibacterial activities. Two members of type II IFNs, IFN-γ and IFN-γrel exist in fish, and they can use CRFB13/CRFB6 and CRFB17 to transfer signaling through STAT1, respectively. Type III IFNs and their receptor subunits have been identified in cartilaginous fish, although not in teleost fish. Type IV IFN is a new IFN identified recently in fish and primitive mammals, which has a significant antiviral function with receptors consisting of CRFB12 and CRFB4. In this report, the current achievements of type I, type II, type III and type IV IFNs in fish were reviewed in respect to gene structure, classification and nomenclature, receptor composition and usage, signaling pathway, and immunological function. Contributions from Chinese scientists on fish IFN composition and nomenclature, receptor usage and signaling, crystal structure, functional specialty, and new IFN finding were summarized. The possible future direction was also proposed in relation with the research on fish IFN systems in this article. It is expected that this article will contribute to systematic understanding of fish IFN system, and may also provide information for potential application of IFNs in antiviral and antibacterial practice in aquaculture.