Binding of Sp1 and Sp3 transcription factors to the Oct-4 gene promoter.
Oct-4 is expressed in embryonic stem cells and is one of the first transcription factors differentially regulated during mouse development. Recent ablation of Oct-4 function in vivo has demonstrated that its expression is essential for preventing embryonic cell differentiation. Several studies have indicated that activation of the Oct-4 TATA-less promoter is mediated by a GC-box representing a high affinity binding site for the transcription factor Sp1. In this study, we have analyzed Oct-4 expression and the activity of the Oct-4 promoter GC box in Sp1 deficient ES cells. We found that in these cells, Oct-4 RNA and protein levels were comparable to wt ES cells and the activity of the Oct-4 promoter GC-box was even increased. Furthermore, the pattern of Oct-4 down-regulation in Sp1 deficient ES cells was unchanged compared to wt cells. Analysis of GC-box binding proteins in extracts from Sp1-/- ES cells revealed that Sp3, another member of the Sp1 transcription factors family, efficiently bound to Sp1 site. These results show that in ES cells Sp1 is not essential for Oct-4 gene activity. Thus, Sp1 function in undifferentiated embryonic cells may be complemented by Sp3 and/or by other GC-box binding transcription factors.
Pesce
M
M
Gene Expression Programme, Germ Cell Biology Group, European Molecular Biology Laboratory, Heidelberg, Germany. m.pesce@med.uniroma2.it
Marin Gomez
M
M
Philipsen
S
S
Schöler
H R
HR
D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004586:Electrophoresis; D020869:Gene Expression Profiling; D051379:Mice; D050814:Octamer Transcription Factor-3; D011401:Promoter Regions, Genetic; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D051705:Sp3 Transcription Factor; D013234:Stem Cells; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D004268:DNA-Binding Proteins; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse; D016329:Sp1 Transcription Factor; C497122:Sp3 protein, mouse; D014157:Transcription Factors; D051705:Sp3 Transcription Factor