AUTHOR=Soponpong Suthinee , Amparyup Piti , Kawai Taro , Tassanakajon Anchalee 

TITLE=Penaeus monodon Interferon Regulatory Factor (PmIRF) Activates IFNs and Antimicrobial Peptide Expression via a STING-Dependent DNA Sensing Pathway

JOURNAL=Frontiers in Immunology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.818267

DOI=10.3389/fimmu.2021.818267

ISSN=1664-3224

ABSTRACT=<p>Interferon regulatory factors (IRFs) are transcription factors found in both vertebrates and invertebrates that were recently identified and found to play an important role in antiviral immunity in black tiger shrimp <italic>Penaeus monodon</italic>. In this study, we investigated the mechanism by which <italic>P. monodon</italic> IRF (<italic>Pm</italic>IRF) regulates the immune-related genes downstream of the cytosolic DNA sensing pathway. Depletion of <italic>Pm</italic>IRF by double-stranded RNA-mediated gene silencing significantly reduced the mRNA expression levels of the IFN-like factors <italic>Pm</italic>Vago1, <italic>Pm</italic>Vago4, and <italic>Pm</italic>Vago5 and antilipopolysaccharide factor 6 (ALF<italic>Pm</italic>6<italic>)</italic> in shrimp. In human embryonic kidney (HEK293T) cells transfected with <italic>Pm</italic>IRF or co-transfected with DEAD-box polypeptide (<italic>Pm</italic>DDX41) and simulator of IFN genes (<italic>Pm</italic>STING) expression plasmids, the promoter activity of IFN-β, nuclear factor (NF-κB), and ALF<italic>Pm</italic>6 was synergistically enhanced following stimulation with the nucleic acid mimics deoxyadenylic–deoxythymidylic acid sodium salt [poly(dA:dT)] and high molecular weight (HMW) polyinosinic–polycytidylic acid [poly(I:C)]. Both nucleic acid mimics also significantly induced <italic>Pm</italic>STING, <italic>Pm</italic>IRF, and ALF<italic>Pm</italic>6 gene expression. Co-immunoprecipitation experiments showed that <italic>Pm</italic>IRF interacted with <italic>Pm</italic>STING in cells stimulated with poly(dA:dT). <italic>Pm</italic>STING, <italic>Pm</italic>IRF, and <italic>Pm</italic>DDX41 were localized in the cytoplasm of unstimulated HEK293T cells and <italic>Pm</italic>IRF and <italic>Pm</italic>DDX41 were translocated to the nucleus upon stimulation with the nucleic acid mimics while <italic>Pm</italic>STING remained in the cytoplasm. These results indicate that <italic>Pm</italic>IRF transduces the pathogen signal <italic>via</italic> the <italic>Pm</italic>DDX41–<italic>Pm</italic>STING DNA sensing pathway to induce downstream production of interferon-like molecules and antimicrobial peptides.</p>