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J Biol Chem. 2014 Aug 22;289(34):23568-81. doi: 10.1074/jbc.M114.554147. Epub 2014 Jul 7.

Interferon γ-inducible protein (IFI) 16 transcriptionally regulates type i interferons and other interferon-stimulated genes and controls the interferon response to both DNA and RNA viruses.

Author information

1
From the Division of Infectious Disease and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605.
2
Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark, and.
3
Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115.
4
From the Division of Infectious Disease and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, evelyn.kurt-jones@umassmed.edu.

Abstract

The interferon γ-inducible protein 16 (IFI16) has recently been linked to the detection of nuclear and cytosolic DNA during infection with herpes simplex virus-1 and HIV. IFI16 binds dsDNA via HIN200 domains and activates stimulator of interferon genes (STING), leading to TANK (TRAF family member-associated NF-κB activator)-binding kinase-1 (TBK1)-dependent phosphorylation of interferon regulatory factor (IRF) 3 and transcription of type I interferons (IFNs) and related genes. To better understand the role of IFI16 in coordinating type I IFN gene regulation, we generated cell lines with stable knockdown of IFI16 and examined responses to DNA and RNA viruses as well as cyclic dinucleotides. As expected, stable knockdown of IFI16 led to a severely attenuated type I IFN response to DNA ligands and viruses. In contrast, expression of the NF-κB-regulated cytokines IL-6 and IL-1β was unaffected in IFI16 knockdown cells, suggesting that the role of IFI16 in sensing these triggers was unique to the type I IFN pathway. Surprisingly, we also found that knockdown of IFI16 led to a severe attenuation of IFN-α and the IFN-stimulated gene retinoic acid-inducible gene I (RIG-I) in response to cyclic GMP-AMP, a second messenger produced by cyclic GMP-AMP synthase (cGAS) as well as RNA ligands and viruses. Analysis of IFI16 knockdown cells revealed compromised occupancy of RNA polymerase II on the IFN-α promoter in these cells, suggesting that transcription of IFN-stimulated genes is dependent on IFI16. These results indicate a broader role for IFI16 in the regulation of the type I IFN response to RNA and DNA viruses in antiviral immunity.

KEYWORDS:

DNA; Host-Pathogen Interaction; Innate Immunity; Interferon; Pattern Recognition Receptor (PRR); RIG-I-like Receptor (RLR); RNA; Toll-like Receptor (TLR); Transcription Regulation; Virus

PMID:
25002588
PMCID:
PMC4156042
DOI:
10.1074/jbc.M114.554147
[Indexed for MEDLINE]
Free PMC Article

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