1. Endosomal Nox2 Facilitates Redox-Dependent Induction of NF-κB by TNF-α
- Author
-
Netanya Y. Spencer, Garry R. Buettner, Qiang Li, John F. Engelhardt, and Fredrick D. Oakley
- Subjects
Dynamins ,Physiology ,Endosome ,Clinical Biochemistry ,Blotting, Western ,Endosomes ,Endocytosis ,Biochemistry ,Superoxide dismutase ,chemistry.chemical_compound ,Mice ,Superoxide Dismutase-1 ,Glutathione Peroxidase GPX1 ,Superoxides ,Cell Line, Tumor ,Animals ,Humans ,Immunoprecipitation ,RNA, Small Interfering ,Molecular Biology ,Cells, Cultured ,General Environmental Science ,chemistry.chemical_classification ,Mice, Knockout ,Reactive oxygen species ,Forum Original Research Communications ,Glutathione Peroxidase ,NADPH oxidase ,biology ,Superoxide ,Superoxide Dismutase ,Tumor Necrosis Factor-alpha ,NF-kappa B ,NADPH Oxidases ,Cell Biology ,Fibroblasts ,Catalase ,TNF Receptor-Associated Factor 2 ,TRADD ,Cell biology ,Mice, Inbred C57BL ,chemistry ,biology.protein ,General Earth and Planetary Sciences ,Signal transduction ,Reactive Oxygen Species ,Oxidation-Reduction - 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.
- Published
- 2009