p47 Negatively Regulates IKK Activation by Inducing the Lysosomal Degradation of Polyubiquitinated NEMO

Nat Commun. 2012;3:1061. doi: 10.1038/ncomms2068.

Abstract

The persistent or excess activation of NF-κB causes various inflammatory and autoimmune diseases, but the molecular mechanisms that negatively regulate NF-κB activation are not fully understood. Here we show that p47, an essential factor for Golgi membrane fusion, associates with the NEMO subunit of the IκB kinase (IKK) complex upon TNF-α or IL-1 stimulation, and inhibits IKK activation. p47 binds to Lys63-linked and linear polyubiquitin chains, which are conjugated to NEMO upon such stimulation. The binding of p47 to polyubiquitinated NEMO triggers the lysosomal degradation of NEMO, thereby inhibiting IKK activation. The silencing of p47 results in enhanced TNF-α- or IL-1-induced IKK activation, and an increased expression of genes encoding inflammatory mediators. Taken together, our results suggest that p47 is critical for negatively regulating stimulation-induced IKK activation in a manner that is mechanistically distinct from the previously characterized negative regulators, such as A20 and CYLD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism
  • Cell Line
  • Electrophoretic Mobility Shift Assay
  • HeLa Cells
  • Humans
  • I-kappa B Kinase / genetics
  • I-kappa B Kinase / metabolism*
  • Immunoprecipitation
  • Jurkat Cells / metabolism
  • Lysosomes / metabolism*
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Polyubiquitin / metabolism*
  • Protein Binding
  • Real-Time Polymerase Chain Reaction
  • Sf9 Cells
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / genetics
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / metabolism*

Substances

  • IKBKG protein, human
  • NF-kappa B
  • Nsfl1c protein, rat
  • Nuclear Proteins
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
  • Polyubiquitin
  • I-kappa B Kinase
  • Adenosine Triphosphatases
  • p97 ATPase