1. A new subtype of type I IFN receptor, CRFB5b, plays an active role in host antiviral and antibacterial functions in Japanese eel (Anguilla japonica).
- Author
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Wang, Tianyu, Lin, Peng, Wang, Yilei, Lai, Xiaojian, Chen, Pengyun, Li, Fuyan, and Feng, Jianjun
- Subjects
ANGUILLA japonica ,RNA interference ,LIVER cells ,TRANSMEMBRANE domains ,SMALL interfering RNA - Abstract
IFNAR1 (type I IFN receptor) plays a crucial role in mammalian host immunity against virus invasion. However, the immune function of the fish teleost IFNAR1, which is also named CRFB5, remains largely unknown. Here, we report the successful cloning of the whole cDNA of the Japanese eel (Anguilla japonica) CRFB5 homolog AjCRFB5b. AjCRFB5b is similar in its three-dimensional structure to grass carp, zebrafish, and humans. It comprises typically two fibronectin-3 domains and a transmembrane region. Expression analysis revealed that AjCRFB5b was widely expressed in all tissues detected, especially in the liver. In vivo, AjCRFB5b was significantly induced in the liver by Aeromonas hydrophila and poly I:C. In vitro, enhanced expression of AjCRFB5b was found in Japanese eel liver cells upon Aeromonas hydrophila infection or poly I:C stimulation. Fluorescence microscopy results showed that EGFP-AjCRFB5b proteins were distributed in the cytoplasm, some in a condensed form in Japanese eel liver cells. Luciferase reporter assays demonstrated that AjCRFB5b overexpression not only significantly induced human IFN-β promoter activity in HEK293 cells and FHM cells but also strongly upregulated immune-related genes in Japanese eel liver cells, including IFN1 (Interferon1), IFN4, IRF5 (Interferon regulatory factor5), and IRF7 of the type I IFN signaling pathway, as well as one of the essential antimicrobial peptides LEAP-2. In addition, RNA interference (RNAi) results showed that knocking down AjCRFB5b caused all five genes to be significantly downregulated in Japanese eel liver cells. Our findings indicate that AjCRFB5b positively regulates host antiviral immune responses by the IRF5- and IRF7-mediated type I IFN signaling pathways and that it also participates in the host immune response to bacterial infection through the production of antimicrobial peptides mediated by LEAP-2. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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