Retinoic acid-mediated down-regulation of Oct3/4 coincides with the loss of promoter occupancy in vivo.
Oct3/4, a hallmark of the earliest stages of embryogenesis, is expressed in undifferentiated embryonal carcinoma (EC) and embryonic stem (ES) cells. Oct3/4 gene expression is dependent on the promoter region, the proximal enhancer and the newly identified distal enhancer. We have analysed in vivo occupancy of these elements. In undifferentiated EC and ES cells, strong footprints were detected at specific sites of all three regulatory elements. These were promptly lost upon RA treatment in ES cells and in P19 EC cells, in parallel with sharply reduced Oct3/4 mRNA levels. Thus, the occupancy of regulatory elements is coupled with Oct3/4 expression, and RA treatment causes coordinated factor displacement, leading to extinction of gene activity. In F9 EC cells, footprint was first abolished at the proximal enhancer. However, this loss of binding site occupancy did not result in a decrease in Oct3/4 mRNA levels. The partial factor displacement seen in F9 EC cells, combined with the observation that EC and ES cells utilize the proximal and distal enhancers in differential manner, indicate the complex pattern of Oct3/4 gene regulation, which could reflect a cell type- and lineage-specific expression of the gene in vivo.
Minucci
S
S
Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
Botquin
V
V
Yeom
Y I
YI
Dey
A
A
Sylvester
I
I
Zand
D J
DJ
Ohbo
K
K
Ozato
K
K
Scholer
H R
HR
D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015536:Down-Regulation; D005786:Gene Expression Regulation; D005796:Genes; D007739:L Cells; D051379:Mice; D008969:Molecular Sequence Data; D050814:Octamer Transcription Factor-3; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D004268:DNA-Binding Proteins; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse; D012333:RNA, Messenger; D014157:Transcription Factors; D014212:Tretinoin