One base pair change abolishes the T cell-restricted activity of a kB-like proto-enhancer element from the interleukin 2 promoter.
The inducible, T cell-specific enhancers of murine and human Interleukin 2 (Il-2) genes contain the kB-like sequence GGGATTTCACC as an essential cis-acting enhancer motif. When cloned in multiple copies this so-called TCEd (distal T cell element) acts as an inducible proto-enhancer element in E14 T lymphoma cells, but not in HeLa cells. In extracts of induced, Il-2 secreting El4 cells three individual protein factors bind to TCEd DNA. The binding of the most prominent factor, named TCF-1 (T cell factor 1), is correlated with the proto-enhancer activity of TCEd. TCF-1 consists of two polypeptides of about 50 kD and 105 kD; the former seems to be related to the 50 kD polypeptide of NF-kB. Purified NF-kB is also able to bind to the TCEd, but TCF-1 binds stronger than NF-kB to TCEd DNA. The conversion of the TCEd to a 'perfect' NF-kB binding site leads to a tighter binding of NF-kB to TCEd DNA and, as a functional consequence, to the activity of the 'converted' TCEd motifs in HeLa cells. Thus, the substitution of the underlined A residue to a C within the GGGATTTCACC motif abolishes its T cell-restricted activity and leads to its functioning in both El4 cells and HeLa cells. These results indicate that lymphocyte-specific factors binding to the TCEd are involved in the control of T cell specific-transcription of the Il-2 gene.
Briegel
K
K
Institut für Virologie und Immunbiologie, Universität Würzburg, FRG.
Hentsch
B
B
Pfeuffer
I
I
Serfling
E
E
D000818:Animals; D001482:Base Composition / Q000235:genetics*; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D006367:HeLa Cells; D051538:Hepatocyte Nuclear Factor 1-alpha; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics*; D051821:Lymphoid Enhancer-Binding Factor 1; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D051822:T Cell Transcription Factor 1; D013601:T-Lymphocytes / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection / Q000235:genetics; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D051538:Hepatocyte Nuclear Factor 1-alpha; C496488:Hnf1a protein, mouse; D007376:Interleukin-2; D051821:Lymphoid Enhancer-Binding Factor 1; D046911:Macromolecular Substances; D016328:NF-kappa B; D051822:T Cell Transcription Factor 1; C497576:TCF7 protein, human; D014157:Transcription Factors; D015500:Chloramphenicol O-Acetyltransferase