title: Overexpression of gamma-glutamylcysteine synthetase suppresses tumor necrosis factor-induced apoptosis and activation of nuclear transcription factor-kappa B and activator protein-1.
abstract: Tumor necrosis factor (TNF) is a highly pleiotropic cytokine whose activity is at least partially regulated by the redox status of the cell. The cellular redox status is controlled primarily by glutathione, a major cellular antioxidant, whose synthesis is regulated by the rate-limiting enzyme gamma-glutamylcysteine synthetase (gamma-GCS). In the present report we investigated the effect of gamma-GCS overexpression on the TNF-induced activation of nuclear transcription factors NF-kappa B and AP-1, stress-activated protein kinase/c-Jun amino-terminal kinase (JNK) and apoptosis. Transfection of cells with gamma-GCS cDNA blocked TNF-induced NF-kappa B activation, cytoplasmic I kappa B alpha degradation, nuclear translocation of p65, and NF-kappa B-dependent gene transcription. gamma-GCS overexpression also completely suppressed NF-kappa B activation induced by phorbol ester and okadaic acid, whereas that induced by H2O2, ceramide, and lipopolysaccharide was minimally affected. gamma-GCS also abolished the activation of AP-1 induced by TNF and inhibited TNF-induced activation of JNK and mitogen-activated protein kinase kinase. TNF-mediated cytotoxicity and activation of caspase-3 were both abrogated in gamma-GCS-overexpressing cells. Overall, our results indicate that most of the pleiotropic actions of TNF are regulated by the glutathione-controlled redox status of the cell.
authors.affiliation: Department of Molecular Oncology, University of Texas MD Anderson Cancer Center, Houston 77030, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Manna
authors.forename: M T
authors.initials: MT
authors.lastname: Kuo
authors.forename: B B
authors.initials: BB
authors.lastname: Aggarwal
mesh_terms: D000818:Animals; D017209:Apoptosis; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015972:Gene Expression Regulation, Neoplastic; D005721:Glutamate-Cysteine Ligase / Q000378:metabolism*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B / Q000378:metabolism*; D051381:Rats; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D020298:U937 Cells
chemical_list: D016328:NF-kappa B; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D005721:Glutamate-Cysteine Ligase