Ataxia telangiectasia mutated kinase mediates NF-κB serine 276 phosphorylation and interferon expression via the IRF7-RIG-I amplification loop in paramyxovirus infection

J Virol. 2015 Mar;89(5):2628-42. doi: 10.1128/JVI.02458-14. Epub 2014 Dec 17.

Abstract

Respiratory syncytial virus (RSV) is a primary etiological agent of childhood lower respiratory tract disease. Molecular patterns induced by active infection trigger a coordinated retinoic acid-inducible gene I (RIG-I)-Toll-like receptor (TLR) signaling response to induce inflammatory cytokines and antiviral mucosal interferons. Recently, we discovered a nuclear oxidative stress-sensitive pathway mediated by the DNA damage response protein, ataxia telangiectasia mutated (ATM), in cytokine-induced NF-κB/RelA Ser 276 phosphorylation. Here we observe that ATM silencing results in enhanced single-strand RNA (ssRNA) replication of RSVand Sendai virus, due to decreased expression and secretion of type I and III interferons (IFNs), despite maintenance of IFN regulatory factor 3 (IRF3)-dependent IFN-stimulated genes (ISGs). In addition to enhanced oxidative stress, RSV replication enhances foci of phosphorylated histone 2AX variant (γH2AX), Ser 1981 phosphorylation of ATM, and IKKγ/NEMO-dependent ATM nuclear export, indicating activation of the DNA damage response. ATM-deficient cells show defective RSV-induced mitogen and stress-activated kinase 1 (MSK-1) Ser 376 phosphorylation and reduced RelA Ser 276 phosphorylation, whose formation is required for IRF7 expression. We observe that RelA inducibly binds the native IFN regulatory factor 7 (IRF7) promoter in an ATM-dependent manner, and IRF7 inducibly binds to the endogenous retinoic acid-inducible gene I (RIG-I) promoter. Ectopic IRF7 expression restores RIG-I expression and type I/III IFN expression in ATM-silenced cells. We conclude that paramyxoviruses trigger the DNA damage response, a pathway required for MSK1 activation of phospho Ser 276 RelA formation to trigger the IRF7-RIG-I amplification loop necessary for mucosal IFN production. These data provide the molecular pathogenesis for defects in the cellular innate immunity of patients with homozygous ATM mutations.

Importance: RNA virus infections trigger cellular response pathways to limit spread to adjacent tissues. This "innate immune response" is mediated by germ line-encoded pattern recognition receptors that trigger activation of two, largely independent, intracellular NF-κB and IRF3 transcription factors. Downstream, expression of protective antiviral interferons is amplified by positive-feedback loops mediated by inducible interferon regulatory factors (IRFs) and retinoic acid inducible gene (RIG-I). Our results indicate that a nuclear oxidative stress- and DNA damage-sensing factor, ATM, is required to mediate a cross talk pathway between NF-κB and IRF7 through mediating phosphorylation of NF-κB. Our studies provide further information about the defects in cellular and innate immunity in patients with inherited ATM mutations.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Ataxia Telangiectasia Mutated Proteins / metabolism*
  • Cell Line
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / metabolism*
  • Epithelial Cells / immunology
  • Epithelial Cells / virology
  • Gene Silencing
  • Humans
  • Interferon Regulatory Factor-7 / metabolism*
  • Interferons / biosynthesis*
  • NF-kappa B / metabolism*
  • Phosphorylation
  • Protein Processing, Post-Translational
  • Respiratory Syncytial Viruses / immunology*
  • Respiratory Syncytial Viruses / physiology
  • Ribosomal Protein S6 Kinases, 90-kDa / metabolism
  • Sendai virus / immunology*
  • Sendai virus / physiology
  • Virus Replication

Substances

  • IRF7 protein, human
  • Interferon Regulatory Factor-7
  • NF-kappa B
  • Interferons
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Ribosomal Protein S6 Kinases, 90-kDa
  • mitogen and stress-activated protein kinase 1
  • DDX58 protein, human
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases