Transcriptional activation by Oct-3: evidence for a specific role of the POU-specific domain in mediating functional interaction with Oct-1.
Oct-3, a member of the POU family of transcription factors, is expressed in pluripotent cells of early mammalian embryos and in undifferentiated embryonal carcinoma cell lines. Using a variety of Oct-3 mutants, we have identified two different domains of Oct-3 which activate transcription in transfected mammalian cells. One of these domains, located in the C-terminal part of the protein, plays a major role in transcriptional activation when Oct-3 is bound to its cognate site, the octamer motif. An Oct-3 mutant containing a single amino acid substitution in the POU homeodomain is unable to bind the octamer target in vitro, yet is still able to activate transcription in an octamer-dependent manner. We provide evidence that transactivation by this mutant involves protein-protein interactions with the ubiquitous octamer binding factor Oct-1. This interaction requires the POU-specific domain of Oct-3 and allows recruitment of Oct-3 to the target promoter even in the absence of Oct-3 DNA binding.
Vigano
M A
MA
DIBIT-Istituto Scientifico H.S. Raffaele, Milano, Italy.
Staudt
L M
LM
D016475:3T3 Cells; D000818:Animals; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D004347:Drug Interactions; D005656:Fungal Proteins / Q000235:genetics; D015870:Gene Expression; D006367:HeLa Cells; D051863:Host Cell Factor C1; D006801:Humans; D051379:Mice; D016297:Mutagenesis, Site-Directed; D050811:Octamer Transcription Factor-1; D050814:Octamer Transcription Factor-3; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation; D014162:Transfection
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; C497692:HCFC1 protein, human; C497693:Hcfc1 protein, mouse; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; D050814:Octamer Transcription Factor-3; C494165:POU2F1 protein, human; C494173:POU5F1 protein, human; C494166:Pou2f1 protein, mouse; C494174:Pou5f1 protein, mouse; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors