From patterning signals to growth and back

During development, pattern formation and tissue growth must be coordinated, suggesting that feedback mechanisms exist between these two processes. Indeed, in some systems, the signals that control pattern formation have been found to be required for growth. Tissue growth is also regulated by dedicated - local and systemic - signals that convey information about tissue architecture and nutritional status. We propose to investigate how these pro-growth signals are integrated. As a first step, we will uncover how patterning signals link molecularly with the cellular growth control machinery. As a model system, we will use Drosophila wing imaginal discs. To overcome the delays associated with traditional genetic analysis, we will develop optogenetic and thermo-sensitive means of controlling signal transduction, focusing on Wingless, a Wnt, and Dpp, a TGF-ß. These tools will be used to identify the patterning signals’ immediate early targets that promote growth, perhaps through regulation of known transducers of systemic signals. In addition, we will investigate whether the activity of patterning signals might be affected by the growth rate, as this could account for scaling. These experiments will uncover, in molecular detail, how various signals are integrated to ensure that tissues grow in a timely and proportionate manner.