A regulatory element in the CD95 (APO-1/Fas) ligand promoter is essential for responsiveness to TCR-mediated activation.
Expression of the CD95 (APO-1/Fas) ligand (CD95L) in activated T cells is a major cause of T cell activation-induced apoptosis. To study the molecular mechanisms of transcriptional control of CD95L expression in T cells, we investigated the human CD95L promoter in Jurkat T cells. Deletion studies revealed that the CD95L proximal promoter sequence from -220 to the transcription start site is essential for T cell stimulation-induced expression of CD95L. In this study, we discovered a novel regulatory element located at -120 of the CD95L promoter which contains DNA binding sites for SP-1 and a yet unknown inducible factor. Mutation analysis demonstrated that binding of the inducible factor to the -120 region is crucial for the biological function of the CD95L promoter upon T cell stimulation. The DNA sequence at -120 also contains two DNA motifs homologous to the binding site for NF-AT. NF-AT does not directly bind to this element. However, cotransfection studies with an NF-AT expression vector showed that NF-AT may confer a strong inducible activity to the CD95L promoter at this regulatory region. Our data also show that the immunosuppressive agent cyclosporin A down-regulates CD95L transcription by inhibiting the function of this positive regulatory element.
Li-Weber
M
M
Tumor Immunology Program, German Cancer Research Center, Heidelberg. m.li-weber@dkfz-heidelberg.de
Laur
O
O
Hekele
A
A
Coy
J
J
Walczak
H
H
Krammer
P H
PH
D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D016572:Cyclosporine / Q000494:pharmacology; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D053222:Fas Ligand Protein; D005786:Gene Expression Regulation; D005809:Genes, Regulator; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D019169:Jurkat Cells; D008024:Ligands; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000276:immunology*; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D019014:fas Receptor / Q000378:metabolism*
D004268:DNA-Binding Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008024:Ligands; D008562:Membrane Glycoproteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011948:Receptors, Antigen, T-Cell; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D019014:fas Receptor; D015759:Ionomycin; D016572:Cyclosporine; D004247:DNA; D013755:Tetradecanoylphorbol Acetate