Delayed activation of HNF-3 beta upon retinoic acid-induced teratocarcinoma cell differentiation.
We have investigated the retinoic acid-mediated activation of the transcriptional regulator HNF-3 beta during differentiation of mouse F9 embryonal carcinoma cells. Using gel shifts, HNF-3 beta DNA binding activity was clearly detected in differentiated cells, while F9 stem cells were devoid of this activity. We also demonstrated that HNF-3 beta mRNA is specific for differentiated cells. Addition of retinoic acid to F9 stem cells results in delayed activation of HNF-3 beta mRNA which can be detected 1-2 days after the initiation of differentiation. HNF-3 beta mRNA concentrations are maximal at approximately 4 days postdifferentiation and stay at elevated levels for at least 4 additional days. Nuclear run-on experiments clearly show that HNF-3 beta is activated at the level of transcriptional initiation, suggesting that the increases of beta-specific DNA binding activity and mRNA concentration are merely a reflection of this activation mechanism. F9 cells can give rise to three distinct differentiated cell types, visceral endoderm, parietal endoderm, and primitive endoderm, and we have observed HNF-3 beta stimulation during the formation of all three tissues. HNF-3 beta stimulation upon visceral endoderm differentiation is accompanied by the activation of HNF-3 target genes such as transthyretin, suggesting that HNF-3 beta is involved in the developmental activation of this gene. In contrast, HNF-3 beta target genes in parietal and primitive endoderm have yet to be identified. However, the stimulation of HNF-3 beta during primitive endoderm formation, which is an extremely early event during murine embryogenesis, points toward a role for the factor in crucial determination processes that occur early during development.
Reichel
R R
RR
Department of Pharmacology and Molecular Biology, Chicago Medical School, Illinois 60064.
Budhiraja
S
S
Jacob
A
A
D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004707:Endoderm / Q000502:physiology; D005786:Gene Expression Regulation / Q000187:drug effects; D051542:Hepatocyte Nuclear Factor 3-beta; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D018243:Teratocarcinoma / Q000473:pathology*; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C496503:Foxa2 protein, mouse; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D051542:Hepatocyte Nuclear Factor 3-beta; D014212:Tretinoin