Modelling the control of Vestigial and Dll expression by Dpp and Wingless in the Drosophila wing disc

This case presentation explores how two key Drosophila morphogens, Decapentaplegic (Dpp) and Wingless (Wg), control the expression of two wing disc transcription factors, Vestigial (Vg) and Distalless (Dll). Two simple models for the potential control of Vg and Dll expression by Dpp and Wg in the mature steady state Drosophila wing pouch are explored. Firstly, a model based on the activation mechanism for Dll in the leg disc was evaluated and dismissed. Secondly, a simple caricature model of Vg activation, based on different thresholds for the contribution of Dpp and Wg to Vg activation, is explored. Although it is limited to modelling the effects of Dpp and Wg, and ignores many other elements later identified as critical to the Vg regulatory pathway, initial analysis suggests that it may be possible to model Vg distribution in the mature wing pouch relatively well using such a simplified steady state model. Further analysis is required to validate the model as it has so far only been assessed against the data used to fit the model parameters. A fuller system of Vg development is then described and the implications for modelling this more complex system discussed.