title: A differential role for endocytosis in receptor-mediated activation of Nox1.
abstract: Internalization of activated receptors to a compartment enriched with NAPDH oxidase and associated signaling molecules is expected to facilitate regulation of redox-mediated signal transduction. The aim of this study was to test the hypothesis that endocytosis is necessary for generation of reactive oxygen species (ROS) by Nox1 and for redox-dependent signaling in smooth muscle cells (SMCs). Within minutes of treatment with tumor necrosis factor (TNF)-alpha or thrombin, SMCs increased cellular levels of ROS that was inhibited by shRNA to Nox1. Treatment of SMC with TNF-alpha induced a dynamin-dependent endosomal generation of ROS, whereas thrombin-mediated ROS production did not occur within endosomes and was not prevented by dominant-negative dynamin (dn-dynamin), but instead required transactivation of the epidermal growth factor receptor (EGFR). Activation of the phosphatidylinositol 3-kinase (PI3K)-Akt-activating transcription factor-1 (ATF-1) pathway by TNF-alpha and thrombin were both Nox1- and dynamin-dependent. In conclusion, we show that formation of specific ligand-receptor complexes results in spatially distinct mechanisms of Nox1 activation and generation of ROS. These findings provide novel insights into the role of compartmentalization for integrating redox-dependent cell signaling.
authors.affiliation: Department of Medicine, University of Iowa, Iowa City, USA. francis-miller@uiowa.edu
authors.forename: Francis J
authors.initials: FJ
authors.lastname: Miller
authors.forename: Xi
authors.initials: X
authors.lastname: Chu
authors.forename: Bojana
authors.initials: B
authors.lastname: Stanic
authors.forename: Xin
authors.initials: X
authors.lastname: Tian
authors.forename: Ram V
authors.initials: RV
authors.lastname: Sharma
authors.forename: Robin L
authors.initials: RL
authors.lastname: Davisson
authors.forename: Fred S
authors.initials: FS
authors.lastname: Lamb
mesh_terms: D051697:Activating Transcription Factor 1 / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D034281:Dynamins / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013917:Thrombin / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D051697:Activating Transcription Factor 1; D007527:Isoenzymes; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D013917:Thrombin; D034281:Dynamins