The same 50-kDa cellular protein binds to the negative regulatory elements of the interleukin 2 receptor alpha-chain gene and the human immunodeficiency virus type 1 long terminal repeat.
We have investigated the biochemical basis for negative regulation of interleukin 2 receptor alpha-chain (IL-2R alpha) gene expression. Transient transfection studies employing internally deleted forms of the IL-2R alpha promoter localized a negative regulatory element (NRE) between nucleotides -400 and -368 relative to the major distal transcription start (cap) site. This 31-base-pair (bp) element is involved in the attenuation of both basal and inducible IL-2R alpha promoter activity. Comparison of this IL-2R alpha NRE with other known regulatory motifs revealed an 11-bp core element (TTCATCCCAGG) that was strikingly similar to a protein-binding domain within the long terminal repeat of the type 1 human immunodeficiency virus (HIV-1). This viral domain has been previously implicated in the negative control of HIV-1 gene expression. In vitro protein-DNA binding studies demonstrated that the same constitutively expressed approximately 50-kDa protein (SP-50) specifically bound to both the IL-2R alpha and HIV-1 NRE core elements. Mutation of the 11-bp IL-2R alpha NRE core element, which disrupted protein binding, significantly augmented basal as well as Tax protein- or phorbol ester-induced IL-2R alpha promoter activity in vivo, suggesting that SP-50 functions as a transcriptional silencer.
Smith
M R
MR
Howard Hughes Medical Institut, Department of Medicine, Duke University Medical Center, Durham, NC 27710.
Greene
W C
WC
D001483:Base Sequence; D002460:Cell Line; D002872:Chromosome Deletion; D004247:DNA / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D005796:Genes; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D046911:Macromolecular Substances; D008970:Molecular Weight; D009154:Mutation; D015375:Receptors, Interleukin-2 / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D013601:T-Lymphocytes / Q000276:immunology
D004279:DNA, Viral; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D015375:Receptors, Interleukin-2; D004247:DNA