title: Nox1 activation by βPix and the role of Ser-340 phosphorylation.
abstract: Rac is an activating factor for Nox1, an O2(-)-generating NADPH oxidase, expressed in the colon and other tissues. Rac requires a GDP-GTP exchange factor for activation. Nox1 activation by βPix has been demonstrated in cell lines. We examined the effects of βPix and its phosphomimetic mutant on endogenous Nox1 in Caco-2 cells transfected with Noxo1 and Noxa1. βPix expression enhanced O2(-) production in resting cells and cells stimulated with EGF or phorbol ester. βPix(S340E) further enhanced O2(-) production, while βPix(S340A) eliminated the βPix effect. βPix(S340E), but not βPix(S340A), had higher affinity and GEF activity for Rac than wild-type βPix. These results suggest that βPix phosphorylation at Ser-340 upregulates Nox1 through Rac activation, confirming Rac as a trigger for acute Nox1-dependent ROS production.
authors.affiliation: Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Kaito
authors.affiliation: Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Kataoka
authors.affiliation: Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Kento
authors.initials: K
authors.lastname: Takechi
authors.affiliation: Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Mihara
authors.affiliation: Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan. Electronic address: tamura@ehime-u.ac.jp.
authors.forename: Minoru
authors.initials: M
authors.lastname: Tamura
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D018938:Caco-2 Cells; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000502:physiology; D006160:Guanosine Triphosphate / Q000737:chemistry; D006801:Humans; D006868:Hydrolysis; D016297:Mutagenesis, Site-Directed; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D064067:Rho Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000737:chemistry
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; C476420:NOXA1 protein, human; C476419:NOXO1 protein, human; D064067:Rho Guanine Nucleotide Exchange Factors; D013481:Superoxides; D012694:Serine; D004815:Epidermal Growth Factor; D006160:Guanosine Triphosphate; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases; C402799:NOX1 protein, human; D020744:rac GTP-Binding Proteins
keywords: Nox1; Noxa1; Noxo1; Phosphorylation; Superoxide; βPix