The NF-kappa B cascade is important in Bcl-xL expression and for the anti-apoptotic effects of the CD28 receptor in primary human CD4+ lymphocytes.
We explored the role of the NF-kappa B pathway in the survival of primary human CD4+ T lymphocytes during CD28 costimulation. Transduction of proliferating CD4+ T cells with a tetracycline-regulated retrovirus encoding for a dominant-interfering, degradation-resistant I-kappaBalpha (inhibitor of kappa B alpha factor) mutant induced apoptosis. Using DNA arrays, we show that Bcl-xL features as a prominent anti-apoptotic member among a number of early CD28-inducible genes. A 1.2-kb segment of the proximal Bcl-xL promoter, linked to a luciferase reporter, responded to CD3/CD28 stimulation in Jurkat cells. Mutation of an NF-kappa B site around -840 decreased, while ectopic expression of I-kappa B kinase-beta (IKK beta) enhanced reporter gene activity. Na+-salicylate and cyclopentenone PGs, direct inhibitors of IKK beta, interfered in the activation of the Bcl-xL promoter and induced apoptosis in CD28-costimulated CD4+ T cells. Moreover, salicylate blocked nuclear localization of NF-kappa B factors that bind to the NF-kappa B binding site in the Bcl-xL promoter, as well as the expression of Bcl-xL protein. HuT-78, a lymphoblastoid T cell line with constitutive NF-kappa B activity, contained elevated levels of Bcl-xL protein and, similar to proliferating CD4+ T cells, was resistant to apoptotic stimuli such as anti-Fas and TNF-alpha. In contrast, the same stimuli readily induced apoptosis in a Jurkat T cell clone with no detectable Bcl-xL expression. Jurkat BMS2 cells also differed from HuT-78 in collapse of mitochondrial membrane potential and superoxide generation in the mitochondrium. Taken together, these data demonstrate that CD3/CD28-induced activation of IKK beta and expression of Bcl-xL promote the survival of primary human CD4+ T lymphocytes.
Division of Clinical Immunology and Allergy, Department of Medicine, University of California, Los Angeles, CA 90095, USA.
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Khoshnan
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Tindell
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Laux
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Bae
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Bennett
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D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D018106:CD28 Antigens / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D020672:I-kappa B Proteins; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D012097:Repressor Proteins / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D013752:Tetracycline / Q000494:pharmacology; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; D018106:CD28 Antigens; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D012097:Repressor Proteins; D051020:bcl-X Protein; C034811:tetracycline resistance-encoding transposon repressor protein; D000072000:NF-KappaB Inhibitor alpha; D013752:Tetracycline