Abstract
Glutathione peroxidase-1 (GPx-1) is a crucial antioxidant enzyme, the deficiency of which promotes atherogenesis. Accordingly, we examined the mechanisms by which GPx-1 deficiency enhances endothelial cell activation and inflammation. In human microvascular endothelial cells, we found that GPx-1 deficiency augments intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression by redox-dependent mechanisms that involve NFκB. Suppression of GPx-1 enhanced TNF-α-induced ROS production and ICAM-1 expression, whereas overexpression of GPx-1 attenuated these TNF-α-mediated responses. GPx-1 deficiency prolonged TNF-α-induced IκBα degradation and activation of ERK1/2 and JNK. JNK or NFκB inhibition attenuated TNF-α induction of ICAM-1 and VCAM-1 expression in GPx-1-deficient and control cells, whereas ERK1/2 inhibition attenuated only VCAM-1 expression. To analyze further signaling pathways involved in GPx-1-mediated protection from TNF-α-induced ROS, we performed microarray analysis of human microvascular endothelial cells treated with TNF-α in the presence and absence of GPx-1. Among the genes whose expression changed significantly, dual specificity phosphatase 4 (DUSP4), encoding an antagonist of MAPK signaling, was down-regulated by GPx-1 suppression. Targeted DUSP4 knockdown enhanced TNF-α-mediated ERK1/2 pathway activation and resulted in increased adhesion molecule expression, indicating that GPx-1 deficiency may augment TNF-α-mediated events, in part, by regulating DUSP4.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Cells, Cultured
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Dual-Specificity Phosphatases / biosynthesis
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Dual-Specificity Phosphatases / genetics
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Endothelial Cells / enzymology*
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Enzyme Activation / genetics
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Gene Expression Regulation, Enzymologic / genetics
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Gene Knockdown Techniques
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Glutathione Peroxidase / genetics
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Glutathione Peroxidase / metabolism*
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Glutathione Peroxidase GPX1
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Humans
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I-kappa B Kinase / genetics
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I-kappa B Kinase / metabolism
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Intercellular Adhesion Molecule-1 / biosynthesis
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Intercellular Adhesion Molecule-1 / genetics
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MAP Kinase Signaling System*
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Mitogen-Activated Protein Kinase 1 / genetics
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Mitogen-Activated Protein Kinase 1 / metabolism
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Mitogen-Activated Protein Kinase 3 / genetics
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Mitogen-Activated Protein Kinase 3 / metabolism
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Mitogen-Activated Protein Kinase Phosphatases / biosynthesis
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Mitogen-Activated Protein Kinase Phosphatases / genetics
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Oxidation-Reduction
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Reactive Oxygen Species / metabolism
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Tumor Necrosis Factor-alpha / genetics
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Tumor Necrosis Factor-alpha / metabolism*
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Vascular Cell Adhesion Molecule-1 / biosynthesis
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Vascular Cell Adhesion Molecule-1 / genetics
Substances
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Reactive Oxygen Species
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Tumor Necrosis Factor-alpha
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Vascular Cell Adhesion Molecule-1
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Intercellular Adhesion Molecule-1
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Glutathione Peroxidase
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I-kappa B Kinase
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MAPK1 protein, human
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinase Phosphatases
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DUSP4 protein, human
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Dual-Specificity Phosphatases
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Glutathione Peroxidase GPX1
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GPX1 protein, human