Research interests

Research in our group is concerned with Development and Evolution. We want to understand the basic genetic mechanisms leading to the origin and evolution of the nervous system and animal body plan. We are working with freshwater polyps (Hydra) and sea anemones (Nematostella). Both animals are members of the >500 Mill years old cnidarians (corals and jelly fish), a phylum that developed the first nervous system. Hydra is also a model system to study regeneration and stem cell differentiation, since it can regenerate intact animals even from suspension of dissociated single cells. Genome projects in Hydra and Nematostella have now revealed the existence of a surprisingly complete set of conserved gene families and pathways regulating development and embryogenesis from cnidarians to vertebrates. Our work is focused on Wnt and BMP signalling. Wnt/Wingless secreted proteins act as short-range inducers and long-range organizers in axis formation, organogenesis, stem cell differentiation and tumorigenesis of vertebrates. Both pathways play also a pivotal role in cnidarian embryogenesis and regeneration. Wnt genes are required for setting up the signalling center (organizer) during gastrulation and regeneration. Notably, also antagonists to Wnt and BMP proteins are acting in cnidarian development and have conserved function (Dkk1/2/4 and Chordin). Our data reveal that Wnts are also required for neuronal differentiation in these early multi-cellular animals. Thus, In combination with the sequenced genomes of Hydra and Nematostella cnidarians can yield important new insights into the function of Wnt and BMP pathways in regulating neurogenesis, regeneration and stem cell differentiation. In a further project we study nematocysts. The exocytosis of these secretory organelles is one of the fastest events in biology, and the forces sustained during explosive discharge require material of extraordinary strength. We identified major structural components (minicollagens) and now analyze their assembly process in a proteome project.

 

Methods applied

We use the complete tool-kit of gain-of-function and loss-of function experiments. We are constructing transgenic lines and perform promotor analyses for wnt, dkk, and bmp genes. We also express recombinant Hydra and Nematostella proteins. We use our stable transgenes and GFP constructs of Hydra interstitial stem cells to analyze neuronal differentiation in embryos, intact polyps, and aggregates by confocal laser scanning microscopy (CLSM), spinning disc confocal microscopy, and 2-photon microscopy. Nematocysts are analyzed by Proteomics and Biochemistry. "