Objective
1- Characterization of new members of the forkhead family in rodents and their homologues in fish. 2-Determination of the biological role of individual members of the forkhead family and vHNF1 by targeted mutation in mice. 3- Transcriptional regulation and promoter analysis in cell-culture systems and in transgenic animals. 4- Three dimensional structural analysis of the forkhead DNA binding domain. 5- Autoregulatory and cross regulatory circuits between HNF3 and HNFI families.
We have isolated and generated mutations of several different genes of the HNF3 family and the vHNFI gene through homologous recombination. The mouse homologs of Drosophila spalt and Tailess were also characterized and mutant mice lacking Tailess were generated. Interestingly, these mice display a severe agressive behaviour, show a variety of defects in the cerebral hemisphere, thalamus and hippocampus and have impaired spatial learning abilities. Analysis of the expression pattern of members of the forkhead familly revealed that HNF3alpha, beta and gamma are differentially expressed during early differentiation of the endoderm and alpha and beta are also expessed in the developing nervous system. Other members characterized in detail, comprise fkh2, expressed in the notochord, and anterior endoderm and neuroectoderm and fkh6, expressed in mesodermal components of the developing gut and in adult kidney and intestine. HNF-3alpha mutant mice are hypoglycaemic and die within the first week of life, even though the hormonal activation of hepatic gluconeogenic enzyme occurs normally. Intestinal brush border enzymes such as lactase and phosphatase are reduced. Mice lacking Fkh6 show reduced postnatal viability and defective regulation of epithelial cell proliferation in the stomach and small intestine resulting in an increased number of dividing intestinal epithelial cells and marked expansion of the proliferative zone. Studies on transcriptional regulation of vHNF1 led to the identification of an indirect mechanism of activation of vHNF1 by the orphan receptors CoupTFs. The salmon HNF1 promoter is controlled synergistically by both CoupTFI and HNF4 orphan receptors binding with different affinity to three closely located sites.Transcriptional regulation of Hnf3gamma by transgenesis and mutagenesis in mice using a 170 kb YAC, indicate that the 3'-flanking region is necessary and sufficient to direct reporter expresssion in organs derived from the endoderm. This enhancer contains a HNF1 binding site crucial for its function, suggesting that vHNF1 rather than HNF1 may be directly involved in the early developmental activation of Hnf3gamma. Analysis of transferrin regulation in transgenic mice indicate that it is an early marker of hepatic differentiation and its expression correlates with postnatal development of oligodendrocytes. Finally, the forkhead/winged helix DNA binding domain has been purified to homogeneity and its interaction with its target sequence examined by different biophysical techniques.
MAJOR SCIENTIFIC BREAKTHROUGS
Our results increased the knowledge of the cross-regulatory circuits that link the HNF3 and HNF1 families as well as with members of the receptors superfamily during differentiation of endodem derived organs. Importantly, several of the mutant mice generated provide interesting models not only of a particular differentiation process (i.e mesenchyme to epithelium signaling and gastrointestinal proliferation in Fk6-/- mice) but also for genetic lessions of the limbic cortex and development of aggressive behavior in humans (i.e. theTailess -/- mutant mice)
Fields of science (EuroSciVoc)
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CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques.
- natural sciencesbiological sciencesneurobiology
- natural sciencesbiological sciencesgeneticsDNA
- natural sciencesbiological sciencesgeneticsmutation
- natural sciencesmathematicspure mathematicsmathematical analysisfunctional analysis
- natural sciencesbiological sciencesbiochemistrybiomoleculesproteinsenzymes
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Call for proposal
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CSC - Cost-sharing contractsCoordinator
75724 PARIS
France