title: IRAK-4 kinase activity-dependent and -independent regulation of lipopolysaccharide-inducible genes.
abstract: IRAK-4 kinase inactive (IRAK-4 KD) knock-in mice display defects in TLR- and IL-1 receptor signaling and are resistant to LPS-induced shock. In the present study we examined the LPS-induced response in IRAK-4 KD mice in more detail. We show that IRAK-4 kinase activity is required for certain aspects of TLR-mediated signaling but not for others. We found that IRAK-4 KD cells displayed reduced JNK and p38 signaling, while NF-kappaB was activated to a normal level but with delayed kinetics compared to wild-type cells. TLR4-mediated IRF3 activation was intact in these cells. Comprehensive analysis of expression of LPS-inducible genes by microarray demonstrated that IRAK-4 KD cells were severely impaired in the expression of many pro-inflammatory genes, suggesting their dependence on IRAK-4 kinase activity. In contrast, the expression of a subset of LPS-induced genes of anti-viral response was not affected by IRAK-4 kinase deficiency. Additionally, we demonstrate that LPS-activated early expression and production of some cytokines, e.g., TNF-alpha, is partially induced in the absence of IRAK-4 kinase activity. This suggests that the partially unaffected TLR4-mediated signaling could still drive expression of these genes in early phases and that IRAK-4 kinase activity is important for a more sustained anti-bacterial response.
authors.affiliation: Novartis Institutes for BioMedical Research, Basel, Switzerland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Koziczak-Holbro
authors.forename: Anton
authors.initials: A
authors.lastname: Glück
authors.forename: Claude
authors.initials: C
authors.lastname: Tschopp
authors.forename: John C
authors.initials: JC
authors.lastname: Mathison
authors.forename: Hermann
authors.initials: H
authors.lastname: Gram
mesh_terms: D000818:Animals; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000097:blood / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism; D050838:Interferon Regulatory Factor-3 / Q000235:genetics / Q000378:metabolism; D053592:Interleukin-1 Receptor-Associated Kinases / Q000235:genetics* / Q000378:metabolism; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D000072000:NF-KappaB Inhibitor alpha; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000235:genetics / Q000378:metabolism
chemical_list: C491768:Ccl2 protein, mouse; D018932:Chemokine CCL2; D016207:Cytokines; D020672:I-kappa B Proteins; D050838:Interferon Regulatory Factor-3; D015850:Interleukin-6; C494233:Irf3 protein, mouse; D008070:Lipopolysaccharides; C000606205:Nfkbia protein, mouse; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D053592:Interleukin-1 Receptor-Associated Kinases; C507774:Irak4 protein, mouse; D020928:Mitogen-Activated Protein Kinases