Viral Induction of the Zinc Finger Antiviral Protein Is IRF3-dependent but NF-κB-independent

Nan Wang,Qingming Dong,Jingjing Li,Rohit K Jangra,Meiyun Fan,Allan R Brasier,Stanley M Lemon,Lawrence M Pfeffer,Kui Li

doi:10.1074/jbc.m109.054486

Abstract

The zinc finger antiviral protein (ZAP) is an interferon-stimulated gene that restricts the replication of retroviruses, alphaviruses, and filoviruses. Relatively little is known, however, regarding the detailed mechanism of ZAP induction during viral infections. We show that, although being inducible by either interferon or virus, expression of ZAP is more efficiently activated by virus than are several other classical interferon-stimulated genes and that viral induction of ZAP occurs under the direct control of interferon regulatory factor 3 (IRF3) independent of interferon paracrine/autocrine signaling. ZAP was up-regulated in cells unresponsive to type I and III interferons upon engagement of TLR3, retinoic inducible gene I/melanoma differentiation-associated gene 5 pathways, or ectopic expression of a constitutively active IRF3 mutant. Conversely, induction of ZAP by virus or dsRNA was severely impaired in cells expressing a dominant-negative mutant IRF3 and completely abrogated in cells lacking IRF3. In contrast to IRF3, ZAP induction was independent of NF-kappaB activity. Mutational analysis of the human ZAP promoter revealed that multiple interferon-stimulated response elements far distal to the transcription start site serve redundantly to control IRF3-dependent induction of ZAP transcription. Chromatin immunoprecipitation assays demonstrated that IRF3 selectively binds the distal interferon-stimulated response elements in human ZAP promoter following viral infection. Collectively, these data suggest that ZAP is a direct target gene of IRF3 action in cellular antiviral responses.

Highlights

Mammalian cells respond to viral infections by the rapid induction of a family of pleiotropic cytokines known as interferons (IFNs).3 Once secreted, IFNs act in an autocrine and/or paracrine
IFN regulatory factor 3 (IRF3) Controls zinc finger antiviral protein (ZAP) Expression the virus-inducible genes were well known IFN-stimulated genes (ISGs), it was unclear whether the disruption of their induction was a direct result of inhibition of IRF3 activation by hepatitis C virus (HCV) or secondary to the blockade of induction of type I/III IFNs, which signal through the JAK-STAT pathway to regulate the expression of these genes
All Five Distal IFN-stimulated responsive elements (ISREs)/IRF element (IRF-E) in the Human ZAP Promoter Are Dispensable for IFN-induced ZAP Transcription—we investigated the role of the ISREs in induction of the human ZAP (hZAP) promoter by IFN␣

Summary

Introduction

Mammalian cells respond to viral infections by the rapid induction of a family of pleiotropic cytokines known as interferons (IFNs).3 Once secreted, IFNs act in an autocrine and/or paracrine. IRF3 Controls ZAP Expression the virus-inducible genes were well known ISGs, it was unclear whether the disruption of their induction was a direct result of inhibition of IRF3 activation by HCV or secondary to the blockade of induction of type I/III IFNs, which signal through the JAK-STAT pathway to regulate the expression of these genes.

Results

Conclusion