TAK1-ECSIT-TRAF6 complex plays a key role in the TLR4 signal to activate NF-κB

J Biol Chem. 2014 Dec 19;289(51):35205-14. doi: 10.1074/jbc.M114.597187. Epub 2014 Nov 4.


ECSIT (evolutionarily conserved signaling intermediate in Toll pathways) is known as a multifunctional regulator in different signals, including Toll-like receptors (TLRs), TGF-β, and BMP. Here, we report a new regulatory role of ECSIT in TLR4-mediated signal. By LPS stimulation, ECSIT formed a high molecular endogenous complex including TAK1 and TRAF6, in which ECSIT interacted with each protein and regulated TAK1 activity, leading to the activation of NF-κB. ECSIT-knockdown THP-1 (ECSIT(KD) THP-1) cells exhibited severe impairments in NF-κB activity, cytokine production, and NF-κB-dependent gene expression, whereas those were dramatically restored by reintroduction of wild type (WT) ECSIT gene. Interestingly, ECSIT mutants, which lack a specific interacting domain for either TAK1 or TRAF6, could not restore these activities. Moreover, no significant changes in both NF-κB activity and cytokine production induced by TLR4 could be seen in TAK1(KD) or TRAF6(KD) THP-1 cells transduced by WT ECSIT, strongly suggesting the essential requirement of TAK1-ECSIT-TRAF6 complex in TLR4 signaling. Taken together, our data demonstrate that the ECSIT complex, including TAK1 and TRAF6, plays a pivotal role in TLR4-mediated signals to activate NF-κB.

Keywords: Cytokine; ECSIT; Inflammation; Innate Immunity; NF-kappaB; Signal Transduction; TNF Receptor-associated Factor 6; Toll-like Receptors; Transforming Growth Factor-β-activated Kinase 1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Blotting, Western
  • Cell Line, Tumor
  • Gene Expression Profiling
  • HEK293 Cells
  • Humans
  • Lipopolysaccharides / pharmacology
  • MAP Kinase Kinase Kinases / genetics
  • MAP Kinase Kinase Kinases / metabolism*
  • Multiprotein Complexes / metabolism
  • Mutation
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Oligonucleotide Array Sequence Analysis
  • Protein Binding / drug effects
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / drug effects
  • TNF Receptor-Associated Factor 6 / genetics
  • TNF Receptor-Associated Factor 6 / metabolism*
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / metabolism*


  • Adaptor Proteins, Signal Transducing
  • Ecsit protein, human
  • Lipopolysaccharides
  • Multiprotein Complexes
  • NF-kappa B
  • TLR4 protein, human
  • TNF Receptor-Associated Factor 6
  • Toll-Like Receptor 4
  • MAP Kinase Kinase Kinases
  • MAP kinase kinase kinase 7