title: Regulation of Nox1 activity via protein kinase A-mediated phosphorylation of NoxA1 and 14-3-3 binding.
abstract: Nox activator 1 (NoxA1) is a homologue of p67(phox) that acts in conjunction with Nox organizer 1 (NoxO1) to regulate reactive oxygen species (ROS) production by the NADPH oxidase Nox1. The phosphorylation of cytosolic regulatory components by multiple kinases plays important roles in assembly and activity of the phagocyte NADPH oxidase (Nox2) system, but little is known about regulation by phosphorylation in the Nox1 system. Here we identify Ser(172) and Ser(461) of NoxA1 as phosphorylation sites for protein kinase A (PKA). A consequence of this phosphorylation was the enhancement of NoxA1 complex formation with 14-3-3 proteins. Using both a transfected human embryonic kidney 293 cell Nox1 model system and endogenous Nox1 in colon cell lines, we showed that the elevation of cAMP inhibits, whereas the inhibition of PKA enhances, Nox1-dependent ROS production through effects on NoxA1. Inhibition of Nox1 activity was intensified by the availability of 14-3-3zeta protein, and this regulatory interaction was dependent on PKA-phosphorylatable sites at Ser(172) and Ser(461) in NoxA1. We showed that phosphorylation and 14-3-3 binding induce the dissociation of NoxA1 from the Nox1 complex at the plasma membrane, suggesting a mechanism for the inhibitory effect on Nox1 activity. Our data establish that PKA-phosphorylated NoxA1 is a new binding partner of 14-3-3 protein(s) and that this forms the basis of a novel mechanism regulating the formation of ROS by Nox1 and, potentially, other NoxA1-regulated Nox family members.
authors.affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: Jun-Sub
authors.initials: JS
authors.lastname: Kim
authors.forename: Becky A
authors.initials: BA
authors.lastname: Diebold
authors.forename: Bernard M
authors.initials: BM
authors.lastname: Babior
authors.forename: Ulla G
authors.initials: UG
authors.lastname: Knaus
authors.forename: Gary M
authors.initials: GM
authors.lastname: Bokoch
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D005981:Glutathione Synthase / Q000378:metabolism; D006801:Humans; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases / Q000378:metabolism / Q000502:physiology*; D010586:Phagocytes / Q000378:metabolism; D010766:Phosphorylation; D017382:Reactive Oxygen Species; D013997:Time Factors
chemical_list: D048948:14-3-3 Proteins; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; C476420:NOXA1 protein, human; D017382:Reactive Oxygen Species; D000242:Cyclic AMP; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases; C402799:NOX1 protein, human; D017868:Cyclic AMP-Dependent Protein Kinases; D005981:Glutathione Synthase