The Small GTPase Rab5c Exerts Bi-Function in Singapore Grouper Iridovirus Infections and Cellular Responses in the Grouper, Epinephelus coioides
The Small GTPase Rab5c Exerts Bi-Function in Singapore Grouper Iridovirus Infections and Cellular Responses in the Grouper, Epinephelus coioides
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DOI：
10.3389/fimmu.2020.02133
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发表时间：
2020-09
影响因子：
7.3
通讯作者：
Liqun Wang;Chen Li;Xinyue Zhang;Min Yang;Shina Wei;Youhua Huang;Q. Qin;Shaowen Wang
中科院分区：
文献类型：
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作者：
Liqun Wang;Chen Li;Xinyue Zhang;Min Yang;Shina Wei;Youhua Huang;Q. Qin;Shaowen Wang
小的GTP酶Rab5是囊泡运输的主要调节者之一，参与内吞作用和内小体成熟等内吞途径的早期阶段。三种Rab5亚型(a、b和c)具有很高的序列同源性，并显示出复杂的功能。然而，Rab5c在病毒感染和细胞免疫反应中的作用仍然知之甚少。本研究在建立新加坡石斑鱼虹彩病毒(SGIV)感染石斑鱼脾(GS)细胞的病毒-细胞感染模型的基础上，探讨了Rab5c在病毒感染和宿主免疫应答中的作用。Rab5c是从斜带石斑鱼中克隆的，命名为EcRab5c。EcRab5c编码一个220个氨基酸的多肽，与东方鱼腥藻和智人的同源性分别为99%和91%。共聚焦成像显示EcRab5c定位于细胞质中的点状结构。然而，成分活性(CA)EcRab5c突变导致囊泡增大，而显性负性(DN)EcRab5c突变导致囊泡结构减少。SGIV感染后EcRab5c的表达水平显著升高。EcRab5c基因敲除或CA/dN EcRab5c过表达可显著抑制SGIV感染。通过单粒子成像分析，我们进一步观察到，EcRab5c的中断在单个病毒水平上损害了SGIV感染早期的关键事件，包括病毒结合、进入和从早期内体到晚期内体的运输。此外，首次对自噬所需的EcRab5c进行了研究。同样，EcRab5c正向调节干扰素相关因子和促炎细胞因子。综上所述，这些数据表明EcRab5c在鱼类虹彩病毒感染和宿主免疫中发挥着双功能作用，这加深了我们对病毒和宿主免疫相互作用的理解。
The small GTPase Rab5 is one of the master regulators of vesicular trafficking that participates in early stages of the endocytic pathway, such as endocytosis and endosome maturation. Three Rab5 isoforms (a, b, and c) share high sequence identity, and exhibit complex functions. However, the role of Rab5c in virus infection and cellular immune responses remains poorly understood. In this study, based on the established virus-cell infection model, Singapore grouper iridovirus (SGIV)-infected grouper spleen (GS) cells, we investigated the role of Rab5c in virus infection and host immune responses. Rab5c was cloned from the orange-spotted grouper, Epinephelus coioides, and termed EcRab5c. EcRab5c encoded a 220-amino-acid polypeptide, showing 99% and 91% identity to Anabas testudineus, and Homo sapiens, respectively. Confocal imaging showed that EcRab5c localized as punctate structures in the cytoplasm. However, a constitutively active (CA) EcRab5c mutant led to enlarged vesicles, while a dominant negative (DN) EcRab5c mutant reduced vesicle structures. EcRab5c expression levels were significantly increased after SGIV infection. EcRab5c knockdown, or CA/DN EcRab5c overexpression significantly inhibited SGIV infection. Using single-particle imaging analysis, we further observed that EcRab5c disruption impaired crucial events at the early stage of SGIV infection, including virus binding, entry, and transport from early to late endosomes, at the single virus level. Furthermore, it is the first time to investigate that EcRab5c is required in autophagy. Equally, EcRab5c positively regulated interferon-related factors and pro-inflammatory cytokines. In summary, these data showed that EcRab5c exerted a bi-functional role on iridovirus infection and host immunity in fish, which furthers our understanding of virus and host immune interactions.