Identification of optineurin as an interleukin-1 receptor-associated kinase 1-binding protein and its role in regulation of MyD88-dependent signaling

J Biol Chem. 2017 Oct 20;292(42):17250-17257. doi: 10.1074/jbc.M117.813899. Epub 2017 Sep 7.


Upon stimulation of toll-like receptors with various microbial ligands, induction of a variety of inflammatory genes is elicited by activation of a myeloid differentiation primary-response protein 88 (MyD88)-dependent signaling pathway. Interleukin-1 (IL-1) receptor-associated kinase 1 (IRAK1) plays an essential role in this pathway by activating nuclear factor κB (NF-κB) and mitogen-activated kinases (MAPKs). Here, we identified optineurin (OPTN) as an IRAK1-binding protein by yeast two-hybrid screening using IRAK1 as bait. A C-terminal fragment of OPTN harboring a ubiquitin-binding domain was co-immunoprecipitated with IRAK1. In reporter analyses, overexpression of OPTN inhibited IL-1β-, IRAK1-, and LPS-induced NF-κB activation. Consistently, OPTN deficiency resulted in increased NF-κB activation in response to IL-1β/LPS stimulation. To address the mechanisms underlying the inhibitory effect of OPTN on NF-κB signaling, we focused on tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6), which is an adaptor protein of IRAK1 and upon polyubiquitination plays a crucial role during NF-κB activation. Overexpression of OPTN prevented TRAF6 polyubiquitination. Furthermore, OPTN H486R mutant, which is unable to recruit the deubiquitinase CYLD, failed to inhibit IRAK1-induced NF-κB activation. These results suggest that the IRAK1-binding protein OPTN negatively regulates IL-1β/LPS-induced NF-κB activation by preventing polyubiquitination of TRAF6.

Keywords: IRAK1; NF-kappaB (NF-κB); TRAF6; interleukin 1 (IL-1); myeloid differentiation primary response gene (88) (MYD88); signal transduction; yeast two-hybrid.

MeSH terms

  • Amino Acid Substitution
  • Animals
  • Cell Cycle Proteins
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / metabolism
  • Deubiquitinating Enzyme CYLD
  • Eye Proteins / genetics
  • Eye Proteins / metabolism*
  • HEK293 Cells
  • Humans
  • Interleukin-1 Receptor-Associated Kinases / genetics
  • Interleukin-1 Receptor-Associated Kinases / metabolism*
  • Intracellular Signaling Peptides and Proteins
  • Lipopolysaccharides / pharmacology
  • Membrane Transport Proteins
  • Mice
  • Mutation, Missense
  • Myeloid Differentiation Factor 88 / genetics
  • Myeloid Differentiation Factor 88 / metabolism*
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • RAW 264.7 Cells
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*
  • TNF Receptor-Associated Factor 6 / genetics
  • TNF Receptor-Associated Factor 6 / metabolism
  • Transcription Factor TFIIIA / genetics
  • Transcription Factor TFIIIA / metabolism*
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism
  • Ubiquitination / drug effects
  • Ubiquitination / physiology


  • Cell Cycle Proteins
  • Eye Proteins
  • Intracellular Signaling Peptides and Proteins
  • Lipopolysaccharides
  • MYD88 protein, human
  • Membrane Transport Proteins
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • OPTN protein, human
  • Optn protein, mouse
  • TNF Receptor-Associated Factor 6
  • Tifab protein, human
  • Transcription Factor TFIIIA
  • Tumor Suppressor Proteins
  • IRAK1 protein, human
  • Interleukin-1 Receptor-Associated Kinases
  • Irak1 protein, mouse
  • CYLD protein, human
  • CYLD protein, mouse
  • Deubiquitinating Enzyme CYLD
  • Cysteine Endopeptidases