Identification of cellular microRNA-136 as a dual regulator of RIG-I-mediated innate immunity that antagonizes H5N1 IAV replication in A549 cells

Abstract

H5N1 influenza A virus (IAV) causes severe respiratory diseases and high mortality rates in animals and humans. MicroRNAs are being increasingly studied to evaluate their potential as therapeutic entities to combat viral infection. However, mechanistic studies delineating the roles of microRNAs in regulating host-H5N1 virus interactions remain scarce. Here, we performed microRNA microarray analysis using A549 human lung epithelial cells infected with a highly pathogenic avian influenza virus. The microRNA expression profile of infected cells identified a small number of microRNAs being dysregulated upon H5N1 influenza A virus infection. Of the differentially expressed microRNAs, miR-136 was up-regulated 5-fold and exhibited potent antiviral activity in vitro against H5N1 influenza A virus, as well as vesicular stomatitis virus. On the one hand, 3′-untranslated region (UTR) reporter analysis revealed a miR-136 binding site in the 3′ UTR of IL-6. However, on the other hand, we subsequently determined that miR-136 meanwhile acts as an immune agonist of retinoic acid-inducible gene 1 (RIG-I), thereby causing IL-6 and IFN-β accumulation in A549 cells. Overall, this study implicates the dual role of miRNA-136 in the regulation of host antiviral innate immunity and suggests an important role for the microRNA-activated pathway in viral infection via pattern recognition receptors.

Protection of macrophages from intracellular pathogens by miR‐182‐5p mimic—a gene expression meta‐analysis approach

“…Moreover, we observed only induction using the less sensitive approach of proteomic analysis. Some reports have indicated that certain transfected miRNAs can induce RIG-I (DDX58) gene expression in epithelial or mesenchymal stem cells, and trigger an antiviral response via specific TLR5 stimulation [67,68]. However, neither DDX58 nor TLR5 expression was induced by miR-182 transfection in this study, making this mechanism unlikely.…”

RIG-I-like receptors: their regulation and roles in RNA sensing

“…Concomitantly, non-coding cellular Y-rNAs were found to accumulate in their 5′-PPP-containing form and to bind to RIG-I in HIV-1-infected cells 59 . Moreover, endogenous RNAs lacking the canonical features of RIG-I agonists, including RNAs cleaved by RNase L 60 and microrNAs (miRNAs) 61 , have been suggested to activate RIG-I in virus-infected cells. Finally, endogenous retroviral elements were shown to activate RIG-I via de-SUMOylation of the host transcriptional repressor tripartite motif-containing 28 (TRIM28; also known as KAP1) 62 .…”

microRNAs in viral acute respiratory infections: immune regulation, biomarkers, therapy, and vaccines

“…Reports have demonstrated that miR-136 interacts at the post-translational level with RIG-I to increase proinflammatory cytokine production [21]. miRNAs, such as let-7, may also act directly on the mRNA of a pro-inflammatory cytokine, such as IL6, to prevent its translation [22].…”