Nuclear factor-kappaB does not mediate the inhibitory effects of dexamethasone on granulocyte-macrophage colony-stimulating factor expression.
Human granulocyte-macrophage colony-stimulating factor (GM-CSF) reporter constructs containing up to 3.3 kb of upstream promoter sequence were transiently transfected into both Jurkat and HUT78 human T-cell lines. In Jurkat cells, stimulation with phorbol 12-myristate 13-acetate (PMA) plus phytohemaglutinin (PHA) produced robust increases in reporter activity, whereas HUT78 cells showed low levels of reporter induction attributable to constitutive nuclear factor (NF)-kappaB activity. Following mutation of either the proximal NF-kappaB site (-85/-76) or the activator protein1 (AP-1) motif within the conserved lymphokine element 0 (CLE0) site (-54/-31), reporter activity was markedly reduced in both cell lines. Despite this dependence on NF-kappaB and CLE0/AP-1, GM-CSF reporter activity was unaffected by dexamethasone in either cell line. Similarly, an NF-kappaB-dependent reporter was also not repressed by dexamethasone, yet GM-CSF release from HUT78 T cells was inhibited. These data therefore confirm a critical role for both NF-kappaB and CLE0 sites in GM-CSF promoter activation and indicate that NF-kappaB may not mediate glucocorticoid-dependent repression of GM-CSF in these cells.
Bergmann
Martin W
MW
Department of Thoracic Medicine, National Heart & Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
Staples
Karl J
KJ
Barnes
Peter J
PJ
Newton
Robert
R
D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001483:Base Sequence; D003907:Dexamethasone / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000502:physiology; D005938:Glucocorticoids / Q000494:pharmacology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D019169:Jurkat Cells; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured
D000893:Anti-Inflammatory Agents; D005938:Glucocorticoids; D007166:Immunosuppressive Agents; D016328:NF-kappa B; D003907:Dexamethasone; D016178:Granulocyte-Macrophage Colony-Stimulating Factor