Abstract
The generation of reactive oxygen species (ROS) in cells stimulated with growth factors requires the activation of phosphatidylinositol 3-kinase (PI3K) and the Rac protein. We report here that the COOH-terminal region of Nox1, a protein related to gp91(phox) (Nox2) of phagocytic cells, is constitutively associated with beta Pix, a guanine nucleotide exchange factor for Rac. Both growth factor-induced ROS production and Rac1 activation were completely blocked in cells depleted of beta Pix by RNA interference. Rac1 was also shown to bind to the COOH-terminal region of Nox1 in a growth factor-dependent manner. Moreover, the depletion of Nox1 by RNA interference inhibited growth factor-induced ROS generation. These results suggest that ROS production in growth factor-stimulated cells is mediated by the sequential activation of PI3K, beta Pix, and Rac1, which then binds to Nox1 to stimulate its NADPH oxidase activity.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Base Sequence
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COS Cells
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Caco-2 Cells
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Cell Line
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Epidermal Growth Factor / pharmacology*
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Guanine Nucleotide Exchange Factors / genetics
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Guanine Nucleotide Exchange Factors / metabolism*
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Humans
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Hydrogen Peroxide / metabolism*
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Mutation
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NADPH Oxidase 1
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NADPH Oxidases / genetics
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NADPH Oxidases / metabolism*
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Phosphatidylinositol 3-Kinases / metabolism*
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RNA, Small Interfering / genetics
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Reactive Oxygen Species / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Rho Guanine Nucleotide Exchange Factors
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Transfection
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rac1 GTP-Binding Protein / genetics
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rac1 GTP-Binding Protein / metabolism*
Substances
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ARHGEF7 protein, human
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Cell Cycle Proteins
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Guanine Nucleotide Exchange Factors
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RNA, Small Interfering
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Reactive Oxygen Species
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Recombinant Fusion Proteins
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Rho Guanine Nucleotide Exchange Factors
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Epidermal Growth Factor
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Hydrogen Peroxide
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NADPH Oxidase 1
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NADPH Oxidases
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NOX1 protein, human
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Phosphatidylinositol 3-Kinases
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rac1 GTP-Binding Protein