NEMO ensures signaling specificity of the pleiotropic IKKβ by directing its kinase activity toward IκBα

Mol Cell. 2012 Jul 13;47(1):111-21. doi: 10.1016/j.molcel.2012.04.020. Epub 2012 May 24.


Besides activating NFκB by phosphorylating IκBs, IKKα/IKKβ kinases are also involved in regulating metabolic insulin signaling, the mTOR pathway, Wnt signaling, and autophagy. How IKKβ enzymatic activity is targeted to stimulus-specific substrates has remained unclear. We show here that NEMO, known to be essential for IKKβ activation by inflammatory stimuli, is also a specificity factor that directs IKKβ activity toward IκBα. Physical interaction and functional competition studies with mutant NEMO and IκB proteins indicate that NEMO functions as a scaffold to recruit IκBα to IKKβ. Interestingly, expression of NEMO mutants that allow for IKKβ activation by the cytokine IL-1, but fail to recruit IκBs, results in hyperphosphorylation of alternative IKKβ substrates. Furthermore IKK's function in autophagy, which is independent of NFκB, is significantly enhanced without NEMO as IκB scaffold. Our work establishes a role for scaffolds such as NEMO in determining stimulus-specific signal transduction via the pleiotropic signaling hub IKK.

Publication types

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

MeSH terms

  • 3T3 Cells
  • Animals
  • Autophagy / drug effects
  • Blotting, Western
  • HEK293 Cells
  • Humans
  • I-kappa B Kinase / genetics
  • I-kappa B Kinase / metabolism*
  • I-kappa B Proteins / genetics
  • I-kappa B Proteins / metabolism*
  • Interleukin-1 / pharmacology
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Microscopy, Fluorescence
  • Multiprotein Complexes / metabolism
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • Phosphorylation / drug effects
  • Protein Binding
  • Signal Transduction*


  • I-kappa B Proteins
  • Interleukin-1
  • Intracellular Signaling Peptides and Proteins
  • Multiprotein Complexes
  • NEMO protein, mouse
  • NF-kappa B
  • NFKBIA protein, human
  • Nfkbia protein, mouse
  • NF-KappaB Inhibitor alpha
  • I-kappa B Kinase