Functions of HNF1 family members in differentiation of the visceral endoderm cell lineage.
The two members of the hepatocyte nuclear factor 1 (HNF1) transcription factor family, HNF1 and variant HNF1 (vHNF1), show a strong homology in their atypical POU-homeodomain and dimerization domain but differ in their transactivation domains. Moreover, two vHNF1 isoforms generated by alternative splicing are present in all tissues expressing this gene. vHnf1-deficient mouse embryos die soon after implantation due to defective visceral endoderm formation, an extraembryonic tissue essential for development and survival of the embryo proper. In contrast, invalidation of Hnf1, which is expressed at later developmental stages than vHnf1, does not lead to embryonic lethality or developmental defects. To examine the specific or potential equivalent functions of vHNF1 isoforms and HNF1 during the process of visceral endoderm differentiation, we stably reexpressed these factors in vHnf1-deficient embryonic stem cells. Analysis of these embryonic stem cells upon differentiation into embryoid bodies shows that vHNF1 isoforms exhibit specific behaviors depending on particular target genes and cooperate in the establishment of a functional visceral endoderm. Furthermore, forced expression of HNF1 in vHnf1-deficient embryonic stem cells fully restores the formation of a mature visceral endoderm with the correct expression profile of early and late markers of this lineage. Thus, in this context, HNF1 functionally replaces both vHNF1 isoforms, suggesting that the different developmental functions of these transcription factors are mainly due to the acquisition of novel expression patterns.
Haumaitre
Cécile
C
Unité 423 INSERM, Hôpital Necker-Enfants Malades, 149 Rue de Sèvres, 75015 Paris, France.
Reber
Michaël
M
Cereghini
Silvia
S
D017398:Alternative Splicing; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D045744:Cell Line, Tumor; D019070:Cell Lineage; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D018274:Electroporation; D004707:Endoderm / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D009687:Nuclear Proteins; D010957:Plasmids / Q000378:metabolism; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D019076:Transgenes
D004268:DNA-Binding Proteins; C496487:HNF1A protein, human; C496495:HNF1B protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; C496488:Hnf1a protein, mouse; C496489:Hnf1a protein, rat; C496496:Hnf1b protein, mouse; D009687:Nuclear Proteins; D020033:Protein Isoforms; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D012313:RNA