Definition of a GC-rich motif as regulatory sequence of the human IL-3 gene: coordinate regulation of the IL-3 gene by CLE2/GC box of the GM-CSF gene in T cell activation.
The human IL-3 gene, located on chromosome 5, contains several cis-acting DNA sequences, i.e. CLE (conserved lymphokine element) and a GC-rich region, similar to the GM-CSF gene. To investigate the role of these elements, the 5' flanking region of the IL-3 gene was attached to a bacterial chloramphenicol acetyltransferase (CAT) gene. The fusion plasmids were analyzed by an in vitro transcription system using Jurkat cell nuclear extract prepared from cells stimulated with phorbol-12-myristate-13-acetate and calcium ionophore (PMA/A23187), introduced into Jurkat cells, expressed transiently, and stimulated by co-transfection of human T cell leukemia virus type I (HTLV-I) encoded transactivator, p40tax. The GC-rich region enhanced TATA-dependent transcription in the in vitro transcription system and also strongly responded to p40tax stimulation in the in vivo cotransfection assay. Using this GC-rich region as a probe, we identified a constitutive DNA-protein complex, alpha, whose binding specificity correlates with transcription activity. However, this element is not sufficient for the expression of the IL-3 gene in response to T cell activation signals (PMA/A23187) and no sequence was found within the IL-3 gene which mediates the response to PMA/A23187. The enhancer sequence which responds to T cell activation signals may be located outside the IL-3 gene and may be shared by other lymphokines, possibly by GM-CSF. We propose that the GM-CSF enhancer (CLE2/GC box) which mediates the response to T cell activation signals may stimulate the expression of the IL-3 gene.
Nishida
J
J
Department of Molecular Biology, DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, CA 94304-1104.
Yoshida
M
M
Arai
K
K
Yokota
T
T
D001482:Base Composition; D001483:Base Sequence; D000001:Calcimycin / Q000494:pharmacology; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D016356:Gene Products, tax / Q000494:pharmacology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics*; D006801:Humans; D007377:Interleukin-3 / Q000235:genetics*; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012689:Sequence Homology, Nucleic Acid; D013601:T-Lymphocytes / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic
D016356:Gene Products, tax; D007377:Interleukin-3; D000001:Calcimycin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D013755:Tetradecanoylphorbol Acetate