The immediate-early gene product Egr-1 regulates the human interleukin-2 receptor beta-chain promoter through noncanonical Egr and Sp1 binding sites.
The interleukin-2 IL-2 receptor beta-chain (IL-2Rbeta) is an essential component of the receptors for IL-2 and IL-15. Although IL-2Rbeta is constitutively expressed by lymphocytes, its expression can be further induced by a number of stimuli, including phorbol 12-myristate 13-acetate (PMA). We have now characterized factors that bind to an enhancer region located between nucleotides -170 and -139 of the human IL-2Rbeta promoter. Both Sp1 and Sp3 bound to the 5' portion of this region, whereas a PMA-inducible factor (PIF) mainly bound to its 3' portion and bound to the Sp binding motifs as well. In Jurkat T cells, induction of PIF DNA binding activity was rapidly induced, required de novo protein synthesis, and was sustained at a high level for at least 23 h. Interestingly, PIF was constitutively activated in human T-cell leukemia virus type 1-transformed MT-2 cells. In this paper, we demonstrate that PIF is Egr-1 based on its recognition by anti-Egr-1 antisera in gel mobility shift assays, even though the IL-2Rbeta DNA binding motif differed substantially from the canonical Egr-1 binding site. In addition, Egr-1 bound to the Sp binding site. In Jurkat cells, both sites were required for maximal IL-2Rbeta promoter activity, and in HeLaS3 cells, transfection of Egr-1 could drive activity of a reporter construct containing both sites. Moreover, Sp1 and Egr-1 could form a complex with kinetics that correlated with the production of Egr-1 in Jurkat cells upon PMA stimulation. Thus, Sp1 and Egr-1 physically and functionally cooperate to mediate maximal IL-2Rbeta promoter activity.
Lin
J X
JX
Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-1674, USA.
Leonard
W J
WJ
D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D051766:Early Growth Response Protein 1; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D017874:Immediate-Early Proteins; D011401:Promoter Regions, Genetic; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2 / Q000235:genetics*; D016329:Sp1 Transcription Factor / Q000378:metabolism; D051705:Sp3 Transcription Factor; D013601:T-Lymphocytes; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*
D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C508024:IL15RA protein, human; D017874:Immediate-Early Proteins; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; D013755:Tetradecanoylphorbol Acetate