Seminar

How Nutrition Regulates Adult Body Size: Lessons from Fruit Flies

CHRISTEN MIRTH, PhD

Our lab focuses on understanding how environmental cues, such as nutrition, affect larval growth to produce a correctly sized adult. We use the fruit fly, Drosophila melanogaster, to elucidate the signalling pathways involved in determining final size. Nutrition regulates body size by controlling larval growth rates and the duration of the larval growth period. Nutrition-sensitive signalling, via the insulin and target of rapamycin (TOR) signalling pathways, regulates the rate of growth. Our work, and that of others, has determined that insulin and TOR act to control the duration of growth by regulating the production of the steroid hormone ecdysone. Our current work examines the molecules responsible for crosstalk between the IIS and ecdysone signalling pathway. Our recent studies suggest that the Forkhead Box O (FoxO) transcription factor, a negative regulator of insulin and TOR signalling, binds directly to a component of the ecdysone receptor, a heterodimeric complex of Ecdysone Receptor (EcR) and Ultraspiracle (Usp). These exciting new results suggest a mechanism that allows the nutrition-dependent signalling pathways and ecdysone signalling to interact to regulate growth and developmental timing.