Drosophila Wg Signalling pathway

In the absence of WG, the protein complex composed by Axin, Shaggy (SGG or ZW3) and APC sequesters and ubiquitinilates Armadillo, leading to a Slmb-dependant degradation by the proteasome. In the absence of ARM, PAN binds to GRO to repress WG targets. Binding of Wingless to Arrow (ARR) or Frizzled (FZ) triggers a set of reactions, starting with the activation of Dishevelled, which in turn inhibits the AXN-SGG-APC complex. This leads (with the help of HIPK) to the accumulation and the stabilisation of ARM. Next, ARM translocates into the nucleus and binds Pangolin (PAN). Then, the ARM/PAN complex with the help of other cofactors (LGS, Nej, Pygo and Hyx) activates the transcription of WG targets. During some patterning processes as in wing disc, Nemo can inhibit PAN and thereby controls the level of WG signalling. To study dynamically the WG signalling pathway, we define two initial states corresponding to the binding of WG ligand and to the absence of binding condition. From these two initial states, we compute the resulting stable states recapitulating the activation or the non activation of the pathway, respectively. For more details on Dpp signalling pathway regulation see [1]; [2]; [3]; [4]; [5].

References