AUTHOR=Hu Naina , Lian Shanshan , Zhu Xiaomei , Chen Xiaomei , Sun Fengzhi , Zhang Lingling , Wang Shi , Bao Zhenmin , Hu Jingjie 

TITLE=Interferon Regulatory Factors Functioned as Activators of the Interferon Pathway in the Scallop Chlamys farreri

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.865707

DOI=10.3389/fmars.2022.865707

ISSN=2296-7745

ABSTRACT=<p>Interferon regulatory factors (<italic>IRF</italic>s) are a family of transcription factors that control many facets during innate and adaptive immune responses. Vertebrate <italic>IRF</italic>s play important roles in regulating the expression of interferons (IFNs) and IFN-stimulated genes, while only limited studies were conducted on invertebrate <italic>IRF</italic>s. In the present study, four <italic>IRF</italic> family genes (<italic>CfIRF1, CfIRF1-like, CfIRF2</italic>, and <italic>CfIRF8</italic>) were identified from Zhikong scallop (<italic>Chlamys farreri</italic>) through whole-genome scanning. <italic>CfIRFs</italic> contain a highly conserved N-terminal DNA-binding domain and a variable C-terminal regulatory domain. <italic>CfIRFs</italic> were constitutively expressed during development as well as in adult tissues, especially in hepatopancreas, hemolymph, gill, and mantle. In hemolymph, qRT-PCR analysis revealed that <italic>CfIRF1, CfIRF1-like</italic>, and <italic>CfIRF2</italic> were significantly upregulated in response to <italic>Vibrio anguillarum</italic> infection, and their encoding proteins could translocate into nucleus. Dual-luciferase reporter assay on <italic>Cf</italic>IRF1, <italic>Cf</italic>IRF1-like, and <italic>Cf</italic>IRF2 showed that these three proteins were capable to induce a strong activation of ISRE promoters. Notably, in comparison with <italic>CfIRF1</italic> and <italic>CfIRF1-like</italic>, <italic>CfIRF2</italic> showed the most sensitive responses in coping with <italic>V. anguillarum</italic>, and consistently, <italic>Cf</italic>IRF2 exhibited the most significant activation on ISRE. This study would provide valuable information for the innate immune roles of the <italic>IRF</italic> gene family in bivalve molluscs.</p>