kuzbanian is required cell autonomously during Notch signalling in the Drosophila wing

The kuzbanian gene encodes a metalloprotease of the ADAM family that is involved in Notch signalling. However, its precise role is a matter of controversy. While original reports concluded that kuz is required on the receiving side of the Notch signalling pathway, a more recent report suggests that Kuz is required on the signal-emitting side for the generation of an active secreted form of the ligand Delta. In this scenario, kuz should act cell non-autonomously. A third possibility is that Kuz is required on the signal-emitting as well as the receiving side. Here I present the clonal analysis of kuz in Drosophila wing. The results show that Kuz acts on the receiving side of the pathway and is not required for Delta signalling. This further confirms the hypothesis that Kuz is required for the release of the intracellular domain of Notch that transduces the signal to the nucleus. The presented results complement recent data that indicate that Kuz can perform the S2 proteolytic cleavage of the Notch receptor that is required for its activation.