Die Rolle der Transmembrandomäne von ADAM17 für die Substratproteolyse
A Disintegrin And Metalloproteinase 17 (ADAM17) is the most important sheddase of epidermal growth factor receptor (EGFR)-ligands. The protease releases, inter alia, tumor growth-factor-alpha and amphiregulin. Therefore, this enzyme is a key regulator of epithelial homeostasis, migration and proliferation. Accordingly, lack of ADAM17 in mice results in embryonic lethality accompanied by severe skin defects. Recently, first human patients were described suffering from a loss-of-function mutation in the ADAM17 gene leading to resembling epithelial defects. Dysregulation of ADAM17 is linked to diverse cutaneous diseases and disturbed epidermal barrier function. The aim of this work was to deepen the understanding of the shedding event, in particular with regard to the domain structure of ADAM17. One aspect of the ADAM-dependent substrate cleavage is that both, enzyme and substrate, need to be in close proximity. Analyzing the structure of ADAM17 and its substrates, a potential role of their transmembrane-domains can be postulated. To find out, whether there is a potential protein-interaction site within the transmembrane region, we used mutagenesis studies and analyzed the release of different EGFR-ligands. Indeed, we identified a potential interaction motif for some substrates. However, our data indicate that there is not one common motif for all substrates. Instead, we propose that the ADAM17 transmembrane region contributes to the recognition of specific substrates such as amphiregulin, while other domains might be responsible for the binding of other EGFR-ligands. Increased knowledge about the substrate selectivity of ADAM17 could lead to deeper insights into epithelial diseases caused by dysregulation of this important protease.