Kappa B binding proteins are constitutively expressed in an IL-2 autocrine human T cell line.
The IL-2 and the IL-2-R alpha genes are both expressed transiently in normal T lymphocytes after Ag or mitogen activation. In contrast, the human T cell line, IARC 301, expresses these two genes constitutively and we have previously demonstrated that its growth depends on the autocrine production of this T cell growth factor and high affinity IL-2R. To dissect the molecular basis for the unusual persistent expression of the IL-2 and IL-2-R alpha genes in these IARC 301 T cells, we have analyzed the interactions of constitutively expressed nuclear proteins with the 5' flanking regions of the IL-2 and IL-2-R alpha genes using both DNase I footprinting and gel retardation techniques. We have found that a region in both genes (-276 to -250 for IL-2-R alpha and -203 to -183 for IL-2), which corresponds to a kappa B enhancer element, is specifically protected by nuclear proteins from IARC 301. In agreement with this finding, both the IL-2 and IL-2-R alpha promoters are active in transient transfection assays in IARC 301 cells. In contrast, mutation of the kappa B enhancer results in markedly attenuated activities of both promoters. Two proteins binding the kappa B sequence, NF-kappa B and KBF1, are constitutively expressed in IARC 301 nuclei and induced by PMA and PHA in Jurkat. They bind to the kappa B motifs with different relative affinities that may reflect their different contribution in the expression of various promoters.
Hémar
A
A
Unité de Génétique Somatique, Institut Pasteur, Paris, France.
Cereghini
S
S
Cornet
V
V
Blank
V
V
Israël
A
A
Greene
W C
WC
Dautry-Varsat
A
A
D001483:Base Sequence; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000502:physiology; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics*; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D015345:Oligonucleotide Probes / Q000737:chemistry; D011401:Promoter Regions, Genetic; D015375:Receptors, Interleukin-2 / Q000235:genetics*; D013601:T-Lymphocytes / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; D007376:Interleukin-2; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; C489548:NFKB1 protein, human; D015345:Oligonucleotide Probes; D015375:Receptors, Interleukin-2; D014157:Transcription Factors