The carboxy-terminal transactivation domain of Oct-4 acquires cell specificity through the POU domain.
The POU transcription factor Oct-4 is expressed in totipotent and pluripotent cells of the early mouse embryo and the germ cell lineage. Transactivation capacities of regions flanking the DNA binding domain of Oct-4 were analyzed in undifferentiated and differentiated cell lines. The amino- and carboxy-terminal regions (N domain and C domain) fused to the Gal4 DNA binding domain both functioned as transactivation domains in all cell lines tested. However, the C domain failed to activate transcription in some cell lines in the context of the native protein. The underlying regulatory mechanism appears to involve the POU domain of Oct-4 and can discriminate between different POU domains, since constructs in which the C domain was instead fused to the POU domain of Pit-1 were again equally active in all cell lines. These results indicate that the C domain is subject to cell-type-specific regulation mediated by the Oct-4 POU domain. Phosphopeptide analysis revealed that the cell-type-specific difference of C-domain activity correlates with a difference in Oct-4 phosphorylation status. Since Oct-4 is expressed in a variety of distinct cell types during murine embryogenesis, these results suggest an additional regulatory mechanism for determining Oct-4 function in rapidly changing cell types during development.
Brehm
A
A
Gene Expression Programme, EMBL, Heidelberg, Germany.
Ohbo
K
K
Schöler
H
H
D016475:3T3 Cells; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D054278:Embryonal Carcinoma Stem Cells; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006367:HeLa Cells; D006801:Humans; D007668:Kidney / Q000196:embryology; D051379:Mice; D014411:Neoplastic Stem Cells; D050814:Octamer Transcription Factor-3; D010748:Phosphopeptides / Q000032:analysis; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000235:genetics*; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D050814:Octamer Transcription Factor-3; D010748:Phosphopeptides; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; C052130:GAL4 protein, S cerevisiae; C494187:POU1F1 protein, human; C494173:POU5F1 protein, human; C494185:Pou1f1 protein, mouse; C494174:Pou5f1 protein, mouse