Retinoic acid-mediated activation of HNF-3 alpha during EC stem cell differentiation.
We present evidence demonstrating that the liver-enriched transcription factor HNF-3 alpha is activated upon retinoic acid-induced differentiation of mouse F9 embryonal carcinoma cells. We have detected increases in the DNA binding activity and mRNA level of HNF-3 alpha. Both are reflections of the actual activation mechanism at the level of transcriptional initiation, which we showed with the help of HNF-3 alpha promoter constructs. Time course studies clearly show that HNF-3 alpha activation is a transient event. Employing Northern blots, HNF-3 alpha mRNA can be detected between 16 and 24 hours post-differentiation, reaches its zenith at approximately 1 day, and then declines to virtually undetectable levels. F9 cells can give rise to three distinct differentiated cell types; visceral endoderm, parietal endoderm, and primitive endoderm. We have clearly shown that HNF-3 alpha stimulation occurs upon primitive endoderm formation. In addition, the transcription factor is also activated during the induction of cell lineages that give rise to parietal and visceral endoderm. HNF-3 alpha stimulation upon visceral endoderm differentiation is accompanied by the activation of HNF-3 target genes such as transthyretin, suggesting that HNF-3 alpha is involved in the developmental activation of this gene. In contrast, HNF-3 alpha target genes in parietal and primitive endoderm have yet to be identified. However, the stimulation of HNF-3 alpha during primitive endoderm formation, which is an extremely early event during murine embryogenesis, points towards a role for the factor in crucial determination processes that occur early during development.
Department of Pharmacology and Molecular Biology, Chicago Medical School, IL 60064.
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A
Jacob
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S
Budhiraja
X
X
Qian
D
D
Clevidence
R H
RH
Costa
R R
RR
Reichel
D000818:Animals; D001483:Base Sequence; D018236:Carcinoma, Embryonal; D002454:Cell Differentiation; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D051541:Hepatocyte Nuclear Factor 3-alpha; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000032:analysis; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014212:Tretinoin / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C496500:Foxa1 protein, mouse; D051541:Hepatocyte Nuclear Factor 3-alpha; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D014212:Tretinoin; D004247:DNA