Endosomal Nox2 Facilitates Redox-Dependent Induction of NF-kappaB by TNF-alpha

Antioxid Redox Signal. 2009 Jun;11(6):1249-63. doi: 10.1089/ars.2008.2407.

Abstract

Growing evidence suggests that NADPH oxidase (Nox)-derived reactive oxygen species (ROS) play important roles in regulating cytokine signaling. We have explored how TNF-alpha induction of Nox-dependent ROS influences NF-kappaB activation. Cellular stimulation by TNF-alpha induced NADPH-dependent superoxide production in the endosomal compartment, and this ROS was required for IKK-mediated activation of NF-kappaB. Inhibiting endocytosis reduced the ability of TNF-alpha to induce both NADPH-dependent endosomal superoxide and NF-kappaB, supporting the notion that redox-dependent signaling of the receptor occurs in the endosome. Molecular analyses demonstrated that endosomal H(2)O(2) was critical for the recruitment of TRAF2 to the TNFR1/TRADD complex after endocytosis. Studies using both Nox2 siRNA and Nox2-knockout primary fibroblasts indicated that Nox2 was critical for TNF-alpha-mediated induction of endosomal superoxide. Redox-active endosomes that form after TNF-alpha or IL-1 beta induction recruit several common proteins (Rac1, Nox2, p67(phox), SOD1), while also retaining specificity for ligand-activated receptor effectors. Our studies suggest that TNF-alpha and IL-1 beta signaling pathways both can use Nox2 to facilitate redox activation of their respective receptors at the endosomal level by promoting the redox-dependent recruitment of TRAFs. These studies help to explain how cellular compartmentalization of redox signals can be used to direct receptor activation from the plasma membrane.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Catalase / pharmacology
  • Cell Line, Tumor
  • Cells, Cultured
  • Dynamins / metabolism
  • Endocytosis / physiology
  • Endosomes / enzymology
  • Endosomes / metabolism*
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Glutathione Peroxidase / genetics
  • Glutathione Peroxidase / physiology
  • Humans
  • Immunoprecipitation
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • NADPH Oxidases / genetics
  • NADPH Oxidases / metabolism*
  • NF-kappa B / metabolism*
  • Oxidation-Reduction / drug effects
  • RNA, Small Interfering
  • Reactive Oxygen Species / metabolism
  • Superoxide Dismutase / pharmacology
  • Superoxide Dismutase-1
  • Superoxides / metabolism
  • TNF Receptor-Associated Factor 2 / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology*

Substances

  • NF-kappa B
  • RNA, Small Interfering
  • Reactive Oxygen Species
  • SOD1 protein, human
  • TNF Receptor-Associated Factor 2
  • Tumor Necrosis Factor-alpha
  • Superoxides
  • glutathione peroxidase GPX1
  • Catalase
  • Glutathione Peroxidase
  • Sod1 protein, mouse
  • Superoxide Dismutase
  • Superoxide Dismutase-1
  • NADPH Oxidases
  • Dynamins