Signal requirements for interleukin 4 promoter activation in human T cells.
We have studied the signal requirements for human IL-4 promoter activation in Jurkat T cells by the use of DNA transfection assays with vectors carrying the IL-4 promoter linked to a reporter gene. Stimulation with calcium (Ca2+) ionophores (ionomycin), but not with phorbol esters (phorbol myristate acetate, PMA) or cyclic AMP elevating agents (prostaglandin E2, PGE2), induced the transcriptional activity of the IL-4 promoter by approximately 3-fold. Costimulation with ionomycin and PGE2 resulted in the same level of IL-4 promoter activity as the stimulation with ionomycin alone. In contrast, costimulation with ionomycin and PMA decreased the activity of the IL-4 promoter by approximately 40% compared to stimulation with ionomycin alone. Induction of Il-4 promoter by ionomycin was partially inhibited (approximately 50% inhibition) in the presence of as high as 2 microgram/ml cyclosporin A (CsA), an inhibitor of the Ca+/calmodulin-dependent phosphatase calcineurin. Under the same conditions, only 0.1 microgram/ml of CsA inhibited by >95% the transactivation of the IL-2 promoter in response to ionomycin and PMA. Transfection of a deletion mutant of the calcineurin catalytic subunit (delta CaM-AI) known to have Ca2+-independent, constitutive phosphatase activity increased IL-4 promoter activity by approximately 14-fold. Stimulation with ionomycin of cells transfected with low doses of delta CaM-AI, further induced IL-4 promoter activity by approximately 2-fold. These results identify the Ca2+-signaling system as a key component of the signal transduction pathway leading to IL-4 promoter activation in Jurkat T cells and suggest a major role of calcineurin in its regulation.
Paliogianni
F
F
Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892-1268, USA.
Hama
N
N
Mavrothalassitis
G J
GJ
Thyphronitis
G
G
Boumpas
D T
DT
D019703:Calcineurin; D002118:Calcium / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D015847:Interleukin-4 / Q000096:biosynthesis / Q000235:genetics*; D016399:Lymphoma, T-Cell; D010749:Phosphoprotein Phosphatases / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D002148:Calmodulin-Binding Proteins; D015847:Interleukin-4; D017868:Cyclic AMP-Dependent Protein Kinases; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D002118:Calcium