Can morphogen activity be enhanced by its inhibitors

Publisher Summary Morphogen form a gradient of concentration and determine the fate of responding cells according to the different concentrations of the morphogen perceived by the cells. Some of the most interesting and best-analyzed examples are the morphogen-mediated events that occur during Drosophila development. This chapter presents two ligand-receptor models for morphogen activity in Drosophila, first with Decapentaplegic (DPP) alone, then with the addition of its inhibitor short gastrulation (SOG). Biological experiments show that the DPP inhibitor SOG actually increases DPP activity along the midline of the Drosophila embryo. It is shown that these simple models provide a mathematical explanation for the effect of SOG: DPP ligand is stored and transported as bound DPP–SOG complex then released near the midline to create the observed peaked morphogen activity.