Down-regulation of human granzyme B expression by glucocorticoids. Dexamethasone inhibits binding to the Ikaros and AP-1 regulatory elements of the granzyme B promoter.
The serine protease granzyme B is an essential component of the granule exocytosis pathway, a major apoptotic mechanism used by cytotoxic T lymphocytes and natural killer cells to induce target cell apoptosis. Granzyme B gene transcription is induced in activated lymphocytes upon antigenic stimulation, and several regulatory regions including CBF, AP-1, and Ikaros binding sites have been shown to be essential in the control of granzyme B promoter activation. Dexamethasone, a glucocorticoid that is widely used as an immunomodulatory and anti-inflammatory agent, inhibits granzyme B mRNA transcript in phytohemagglutinin-activated peripheral blood mononuclear cells. Transfection of a reporter construct containing the -148 to +60 region of the human granzyme B promoter demonstrated that this region was the target for dexamethasone repression. Mutation of Ikaros or AP-1 binding sites in the context of the granzyme B promoter demonstrated that both sites participate in dexamethasone-mediated inhibition of the granzyme B promoter activity. Electromobility shift assay revealed that dexamethasone abolished the binding of nuclear transcription factors to the Ikaros binding site and reduced AP-1 binding activity. These results indicate that dexamethasone is able to abrogate the transcriptional activity of the human granzyme B gene promoter by inhibiting the binding of nuclear factors at the AP-1 and Ikaros sites.
Wargnier
A
A
INSERM U462, Institut d'Hématologie, 75010 Paris, France.
Lafaurie
C
C
Legros-Maïda
S
S
Bourge
J F
JF
Sigaux
F
F
Sasportes
M
M
Paul
P
P
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D015536:Down-Regulation; D005938:Glucocorticoids / Q000494:pharmacology*; D053804:Granzymes; D006801:Humans; D051740:Ikaros Transcription Factor; D007108:Immune Tolerance; D007963:Leukocytes, Mononuclear / Q000187:drug effects*; D009687:Nuclear Proteins / Q000378:metabolism*; D010835:Phytohemagglutinins / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D012697:Serine Endopeptidases / Q000096:biosynthesis* / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D005938:Glucocorticoids; C497239:IKZF1 protein, human; D009687:Nuclear Proteins; D010835:Phytohemagglutinins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D051740:Ikaros Transcription Factor; D003907:Dexamethasone; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases