In vivo regulation of interleukin‐2 receptor alpha gene transcription by the coordinated binding of constitutive and inducible factors in human primary T cells

• Published in: The EMBO journal 1995-10, Vol.14 (20), p.5060-5072
• Main Authors: Algarté, M., Lécine, P., Costello, R., Plet, A., Olive, D., Imbert, J.
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents - pharmacology; Base Sequence; Biochemistry, Molecular Biology; Biological Transport; Cell Compartmentation; Cell Differentiation; DNA Footprinting; DNA-Binding Proteins - metabolism; Enhancer Elements, Genetic; Gene Expression Regulation; Humans; Life Sciences; Lymphocyte Activation; Models, Genetic; Molecular Sequence Data; NF-kappa B - metabolism; NF-kappa B p50 Subunit; Nuclear Proteins - metabolism; Proline - analogs & derivatives; Proline - pharmacology; Promoter Regions, Genetic; Protein Binding; Receptors, Interleukin-2 - genetics; Serum Response Factor; T-Lymphocytes - metabolism; Thiocarbamates - pharmacology; Transcription, Genetic; Tumor Cells, Cultured
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1995.tb00188.x

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.