Research objectives and content
During vertebrate development gastrulation leads to the formation of three germlayers, the ectoderm, mesoderm and endoderm. So far very little is known about the differentiation of the endoderm, the germ layer giving rise to the 1ining of the gut and associated organs like liver and pancreas as well as the lining of the lungs. There is strong evidence that transcription factors of the GATA family are functionally involved in endoderm specification. The Drosophila gene serpent, which is essential for normal patterning of the gut is a homologue of the GATA family and targeted mutation of mouse GATA4 has been shown to block visceral endoderm formation. In zebrafish GATA5 and 6 are expressed in cells fated to be endoderm prior to gastrulation, Very recent results demonstrate that ectopically expressed GATA5 induces an endodermal marker gene in Xenopus animal cap explants. In the proposed project the function of GATA4, 5 and 6 in endoderm formation will be analyzed. Therefore the background knowledge and use of explants in the frog Xenopus laevis will be exploited as well as the availability of mutants in zebrafish. The expression pattern of GATA4, 5 and 6 will be characterized with respect to the well known cell fates in Xenopus. More importantly GATA4, 5 and 6 will be used as early molecular markers to investigate the signalling pathways that give rise to endoderm. Zebrafish mutants will be analyzed for early effects on endoderm formation and GATA-expression. By ectopic expression of GATA family members, and use of their dominant negative forms in Xenopus and zebrafish the function of these factors in endoderm specification will be analyzed. The designed experiments will improve the currently poor understanding of endoderm formation in vertebrates.
Training content (objective, benefit and expected impact)
Working in my chosen host institution will enable me to extend the line of inquiries started during my Ph.D. but at the same time to graft on new approaches and systems. The proposed project gives me the opportunity to learn a wide range of new techniques, including in situ hybridization on sections, endoderm explants, RNAse protection analysis and targeted RNA injections. Most importantly I will be introduced to work on zebrafish, a newly established vertebrate system getting more and more important for the studies of developmental genetics. As the DBRC is excellently equipped and molecular as well es embryological methods are well established in Roger Patient's group, efficient work on the proposed project will be guaranteed.The DBRC consists of 11 groups working on vertebrate development in many different organisms. This provides a very collaborative environment and my learning experience will be greatly expanded.
Links with industry / industrial relevance (22)
The planned experiments are part of a basic research project. without direct link to industry. However the DBRC as a whole has very good contacts to a broad range of companies, so that potential applications will be fully exploited.