Cooperative transcriptional activity of Jun and Stat3 beta, a short form of Stat3.
To identify proteins that regulate the transcriptional activity of c-Jun, we have used the yeast two-hybrid screen to detect mammalian polypeptides that might interact functionally with the N-terminal segment of c-Jun, a known regulatory region. Among the proteins identified is a short form of Stat3 (designated Stat3 beta). Stat3 beta is missing the 55 C-terminal amino acid residues of the long form (Stat3 alpha) and has 7 additional amino acid residues at its C terminus. In the absence of added cytokines, expression of Stat3 beta (but not Stat3 alpha) in transfected cells activated a promoter containing the interleukin 6 responsive element of the rat alpha 2-macroglobulin gene; coexpression of Stat3 beta and c-Jun led to enhanced cooperative activation of the promoter. Nuclear extracts of cells transfected with a Stat3 beta expression plasmid formed a complex with an oligonucleotide containing a Stat3 binding site, whereas extracts of cells transfected with a Stat3 alpha plasmid did not. We conclude that there is a short form of Stat3 (Stat3 beta), that Stat3 beta is transcriptionally active under conditions where Stat3 alpha is not, and that Stat3 beta and c-Jun are capable of cooperative activation of certain promoters.
Schaefer
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Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185, USA.
Sanders
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Nathans
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015850:Interleukin-6 / Q000494:pharmacology / Q000502:physiology; D008322:Mammals; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D055503:Protein Multimerization; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D050796:STAT3 Transcription Factor; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D017384:Sequence Deletion; D013937:Thymidine Kinase / Q000235:genetics; D015534:Trans-Activators / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D020798:Two-Hybrid System Techniques; D000511:alpha-Macroglobulins / Q000096:biosynthesis* / Q000235:genetics
D004268:DNA-Binding Proteins; D015850:Interleukin-6; D009838:Oligodeoxyribonucleotides; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011994:Recombinant Proteins; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D000511:alpha-Macroglobulins; D015500:Chloramphenicol O-Acetyltransferase; D013937:Thymidine Kinase