In vivo regulation of interleukin-2 receptor alpha gene transcription by the coordinated binding of constitutive and inducible factors in human primary T cells.
IL-2R alpha transcription is developmentally restricted to T cells and physiologically dependent on specific stimuli such as antigen recognition. To analyse the mechanisms used to activate IL-2R alpha transcription as well as those used to block it in non-expressing cells, we determined the protein-DNA interactions at the IL-2R alpha locus in three different cell types using the DMS/LMPCR genomic footprinting method. CD25/IL-2R alpha can be efficiently induced in primary human T cells since approximately 100% express this gene when receiving an appropriate combination of mitogenic stimuli. To understand why IL-2R alpha is not expressed in other haematopoietic cell types, we analysed BJAB B lymphoma cells which do not express the IL-2R alpha gene and contain constitutively active nuclear NF-kappa B. Primary fibroblasts from embryo and adult skin were selected to examine the mechanisms that may be used to keep the IL-2R alpha gene inactive in non-haematopoietic cells. The three main results are: (i) the stable in vivo occupancy of IL-2R alpha kappa B element in resting T cells, most probably by constitutive NF-kappa B p50 homodimer that could impair SRF binding to the flanking SRE/CArG box; (ii) its inducible occupancy by NF-kappa B p50-p65 associated with the binding of an SRE/CArG box DNA-binding factor upon mitogenic stimulation; and (iii) a correlation between the precommitment of T cells to activation and the presence of stable preassembled protein-DNA complexes in contrast with the bare IL-2R alpha locus in non-T cells.
Algarté
M
M
INSERM U119, Marseille, France.
Lécine
P
P
Costello
R
R
Plet
A
A
Olive
D
D
Imbert
J
J
D000970:Antineoplastic Agents / Q000494:pharmacology; D001483:Base Sequence; D001692:Biological Transport; D002451:Cell Compartmentation; D002454:Cell Differentiation; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D006801:Humans; D008213:Lymphocyte Activation; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D009687:Nuclear Proteins / Q000378:metabolism; D011392:Proline / Q000031:analogs & derivatives / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015375:Receptors, Interleukin-2 / Q000235:genetics*; D026362:Serum Response Factor; D013601:T-Lymphocytes / Q000378:metabolism*; D013859:Thiocarbamates / Q000494:pharmacology; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D009687:Nuclear Proteins; D015375:Receptors, Interleukin-2; D026362:Serum Response Factor; D013859:Thiocarbamates; C066229:prolinedithiocarbamate; D011392:Proline