MicroRNA regulation of IFN-beta protein expression: rapid and sensitive modulation of the innate immune response.
IFN-beta production is an inaugural event in the innate immune response to viral infections, with relatively small fold changes in IFN-beta expression resulting in the activation of important antiviral signaling cascades. In our rapid SIV/macaque model of HIV encephalitis, the virus enters the CNS within 4 d of infection, accompanied by a marked IFN-beta response that wanes as SIV replication is controlled. The centrality of IFN-beta to the innate antiviral response in the CNS combines with the potential inflammatory damage associated with long-term activation of this pathway to suggest that IFN-beta may be subject to regulatory fine-tuning in addition to well-established transcriptional and message stability mechanisms of regulation. In this paper, we present for the first time evidence that microRNAs (miRNAs), including miR-26a, -34a, -145, and let-7b, may directly regulate IFN-beta in human and macaque cells. In primary primate macrophages, the main cell type implicated in HIV and SIV infection in the CNS, specific miRNAs reduce, whereas miRNA inhibitors enhance, IFN-beta protein production. The potential biologic significance of this regulation is supported by evidence of an apparent negative feedback loop, with increased expression of three IFN-beta-regulating miRNAs by primate macrophages exposed to recombinant IFN-beta or stimulated to produce IFN-beta. Thus, miRNAs may contribute significantly to the regulation of IFN-beta in innate immune responses.
Witwer
Kenneth W
KW
Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, 733 North Broadway, Baltimore, MD 21205, USA.
Sisk
Jeanne M
JM
Gama
Lucio
L
Clements
Janice E
JE
D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology; D016899:Interferon-beta / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D008254:Macaca nemestrina; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D014176:Protein Biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014777:Virus Diseases / Q000276:immunology
D020413:3' Untranslated Regions; D016899:Interferon-beta; D035683:MicroRNAs; D012333:RNA, Messenger; C541010:MIRN145 microRNA, human; C528163:MIRN26 microRNA, human; C522425:MIRN34 microRNA, human; C487931:mirnlet7 microRNA, human