title: Tumor necrosis factor-alpha (TNF-alpha) signal transduction through ceramide. Dissociation of growth inhibitory effects of TNF-alpha from activation of nuclear factor-kappa B.
abstract: Tumor necrosis factor-alpha (TNF-alpha) exerts pleiotropic biologic effects. Although TNF-alpha appears to activate a number of signal transduction pathways, the role of second messengers in mediating the different effects of TNF-alpha are not well defined. In this study, we investigated the role of ceramide as an intracellular mediator of TNF-alpha action. In Jurkat T cells, TNF-alpha caused early activation of the sphingomyelin cycle with peak hydrolysis of sphingomyelin observed at 30 min following addition of TNF-alpha. In this cell line, TNF-alpha caused potent activation of nuclear factor-kappa B (NF-kappa B) and exerted potent cytostatic/cytocidal activity. C2-ceramide mimicked the effects of TNF-alpha on cell growth in a dose-dependent manner, but C2-ceramide was unable to induce activation of NF-kappa B under multiple conditions investigated. C2-ceramide, however, enhanced activation of NF-kappa B in response to TNF-alpha with peak effects observed at a concentration of C2-ceramide of 5 microM. Thus, ceramide functions as a selective mediator of the cytostatic/cytotoxic effects of TNF-alpha and plays a positive feedback role in activation of NF-kappa B. TNF-alpha signaling, therefore, involves multiple second-messenger pathways that function independently or coordinately to transduce distinct functions of TNF-alpha.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
authors.forename: G S
authors.initials: GS
authors.lastname: Dbaibo
authors.forename: L M
authors.initials: LM
authors.lastname: Obeid
authors.forename: Y A
authors.initials: YA
authors.lastname: Hannun
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D015459:Leukemia-Lymphoma, Adult T-Cell; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D015345:Oligonucleotide Probes; D011401:Promoter Regions, Genetic; D015375:Receptors, Interleukin-2 / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013109:Sphingomyelins / Q000378:metabolism*; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D002518:Ceramides; D016328:NF-kappa B; D015345:Oligonucleotide Probes; D015375:Receptors, Interleukin-2; D013109:Sphingomyelins; D014409:Tumor Necrosis Factor-alpha