Knospung-steuernde Gene in Hydra vulgaris: Ein evolutionsgeschichtlich alter FGFR kontrolliert die Knopsenablösung

By expression screening we have identified a fibroblast growth factor receptor (FGFR)-like tyrosine kinase (Kringelchen) from Hydra vulgaris. The highly dynamic expression pattern during budding suggested that kringelchen plays an important role during the asexual propagation of Hydra. After treatment with SU5402, a specific inhibitor of FGFR activity, as well as with antisense-oligonucleotides against kringelchen, polyps developed a branched phenotype. Bud detachment failed. This led to the hypothesis that Kringelchen is essential for bud detachment. The detailed analysis of kringelchen expression pattern during head- and foot regeneration as well as during development of cell aggregates furthermore suggests an involvement in general patterning and axis formation. The isolation of a cDNA-fragment encoding an FGF-like protein in Hydra indicates that Kringelchen binds to FGFs.