A20 Is a Negative Regulator of IFN Regulatory Factor 3 Signaling1

IFN regulatory factor 3 (IRF-3) is a critical transcription factor that regulates an establishment of innate immune status following detection of viral pathogens. Recent studies have revealed that two IκB kinase (IKK)-like kinases, NF-κB-activating kinase/Traf family member-associated NF-κB activator-binding kinase 1 and IKK-i/IKKε, are responsible for activation of IRF-3, but the regulatory mechanism of the IRF-3 signaling pathway has not been fully understood. In this study, we report that IRF-3 activation is suppressed by A20, which was initially identified as an inhibitor of apoptosis and inducibly expressed by dsRNA. A20 physically interacts with NF-κB-activating kinase/Traf family member-associated NF-κB activator-binding kinase 1 and IKK-i/IKKε, and inhibits dimerization of IRF-3 following engagement of TLR3 by dsRNA or Newcastle disease virus infection, leading to suppression of the IFN stimulation response element- and IFN-β promoter-dependent transcription. Importantly, knocking down of A20 expression by RNA interference results in enhanced IRF-3-dependent transcription triggered by the stimulation of TLR3 or virus infection. Our study thus demonstrates that A20 is a candidate negative regulator of the signaling cascade to IRF-3 activation in the innate antiviral response.

[1]  H. S. Warren,et al.  Toll-like receptors. , 2005, Critical care medicine.

[2]  E. Nishida,et al.  Direct triggering of the type I interferon system by virus infection: activation of a transcription factor complex containing IRF‐3 and CBP/p300 , 1998, The EMBO journal.

[3]  T. Taniguchi,et al.  IRF family of transcription factors as regulators of host defense. , 2001, Annual review of immunology.

[4]  S. Akira,et al.  TRAM is specifically involved in the Toll-like receptor 4–mediated MyD88-independent signaling pathway , 2003, Nature Immunology.

[5]  K. Honda,et al.  Essential role of IRF-3 in lipopolysaccharide-induced interferon-beta gene expression and endotoxin shock. , 2003, Biochemical and biophysical research communications.

[6]  K. Senger,et al.  Gene repression by coactivator repulsion. , 2000, Molecular cell.

[7]  G. Sen,et al.  Viruses and interferons. , 2001, Annual review of microbiology.

[8]  Guo-Ping Zhou,et al.  Triggering the Interferon Antiviral Response Through an IKK-Related Pathway , 2003, Science.

[9]  M. Karin,et al.  NAK is an IκB kinase-activating kinase , 2000, Nature.

[10]  T. Fujita,et al.  TIR-containing Adapter Molecule (TICAM)-2, a Bridging Adapter Recruiting to Toll-like Receptor 4 TICAM-1 That Induces Interferon-β* , 2003, Journal of Biological Chemistry.

[11]  J. Hiscott,et al.  The IRF-3 Transcription Factor Mediates Sendai Virus-Induced Apoptosis , 2000, Journal of Virology.

[12]  T. Saitoh,et al.  Lymphotoxin‐β receptor mediates NEMO‐independent NF‐κB activation , 2002 .

[13]  A. Ma,et al.  Failure to regulate TNF-induced NF-kappaB and cell death responses in A20-deficient mice. , 2000, Science.

[14]  P. Moynagh,et al.  Regulation of Toll-like receptor 4 signalling by A20 zinc finger protein. , 2003, Biochemical and biophysical research communications.

[15]  Charles A. Janeway,et al.  IRAK-M Is a Negative Regulator of Toll-like Receptor Signaling , 2002, Cell.

[16]  F. Martinon,et al.  RIP1 is an essential mediator of Toll-like receptor 3–induced NF-κB activation , 2004, Nature Immunology.

[17]  K. Taira,et al.  U6 promoter–driven siRNAs with four uridine 3′ overhangs efficiently suppress targeted gene expression in mammalian cells , 2002, Nature Biotechnology.

[18]  J. Hiscott,et al.  Lipopolysaccharide Inhibits Virus-mediated Induction of Interferon Genes by Disruption of Nuclear Transport of Interferon Regulatory Factors 3 and 7* , 1999, The Journal of Biological Chemistry.

[19]  Daniel R. Caffrey,et al.  LPS-TLR4 Signaling to IRF-3/7 and NF-κB Involves the Toll Adapters TRAM and TRIF , 2003, The Journal of experimental medicine.

[20]  M. Kubo,et al.  SOCS1/JAB is a negative regulator of LPS-induced macrophage activation. , 2002, Immunity.

[21]  R. Beyaert,et al.  A20 and A20-binding proteins as cellular inhibitors of nuclear factor-kappa B-dependent gene expression and apoptosis. , 2000, Biochemical pharmacology.

[22]  Kenji Nakanishi,et al.  SOCS-1 participates in negative regulation of LPS responses. , 2002, Immunity.

[23]  R. Contreras,et al.  The Zinc Finger Protein A20 Inhibits TNF-induced NF-κB–dependent Gene Expression by Interfering with an RIP- or TRAF2-mediated Transactivation Signal and Directly Binds to a Novel NF-κB–inhibiting Protein ABIN , 1999, The Journal of cell biology.

[24]  G. Gross,et al.  Platelet-derived growth factor isoforms AA, AB, and BB differentially activate poly r(I):r(C)-induced genes in human fibroblast FS4 cells. , 1992, DNA and cell biology.

[25]  H. Ploegh,et al.  Zinc-finger protein A20, a regulator of inflammation and cell survival, has de-ubiquitinating activity. , 2004, The Biochemical journal.

[26]  Shizuo Akira,et al.  Toll/IL-1 Receptor Domain-Containing Adaptor Inducing IFN-β (TRIF) Associates with TNF Receptor-Associated Factor 6 and TANK-Binding Kinase 1, and Activates Two Distinct Transcription Factors, NF-κB and IFN-Regulatory Factor-3, in the Toll-Like Receptor Signaling 1 , 2003, The Journal of Immunology.

[27]  Z. Zhai,et al.  ZNF216 Is an A20-like and IκB Kinase γ-Interacting Inhibitor of NFκB Activation* , 2004, Journal of Biological Chemistry.

[28]  R. Beyaert,et al.  Functional redundancy of the zinc fingers of A20 for inhibition of NF‐κB activation and protein–protein interactions , 2001, FEBS letters.

[29]  Shizuo Akira,et al.  TLR signaling pathways. , 2004, Seminars in immunology.

[30]  E. R. Taylor,et al.  Isolation and characterization of two novel A20-like proteins. , 2001, The Biochemical journal.

[31]  G Cantarella,et al.  Recruitment of the IKK signalosome to the p55 TNF receptor: RIP and A20 bind to NEMO (IKKgamma) upon receptor stimulation. , 2000, Immunity.

[32]  J. Hiscott,et al.  Multiple signaling pathways leading to the activation of interferon regulatory factor 3. , 2002, Biochemical pharmacology.

[33]  S. Akira,et al.  Cutting Edge: A Novel Toll/IL-1 Receptor Domain-Containing Adapter That Preferentially Activates the IFN-β Promoter in the Toll-Like Receptor Signaling1 , 2002, The Journal of Immunology.

[34]  F. Inagaki,et al.  Identification of Ser-386 of Interferon Regulatory Factor 3 as Critical Target for Inducible Phosphorylation That Determines Activation* , 2004, Journal of Biological Chemistry.

[35]  T. Maniatis,et al.  IKKε and TBK1 are essential components of the IRF3 signaling pathway , 2003, Nature Immunology.

[36]  N. Sonenberg,et al.  The protein kinase PKR: a molecular clock that sequentially activates survival and death programs , 2004, The EMBO journal.

[37]  F. Liew,et al.  ST2 is an inhibitor of interleukin 1 receptor and Toll-like receptor 4 signaling and maintains endotoxin tolerance , 2004, Nature Immunology.