Nutrient-regulated neuronal circuits and insulin signaling

In Drosophila, there are 14 neurosecretory neurons located in the pars intercerebralis (the fly hypothalamus) that synthesize and secrete 3 of the 8 Drosophila insulin-like peptides (Dilps). Dilps bind to and activate the single Insulin-like tyrosine kinase receptor, which leads to downstream activation of the evolutionarily conserved PI3-kinase growth signaling pathway. Axon terminals of these 14 neurosecretory neurons, known as the Insulin-producing cells (IPCs) contact tissues outside the brain, including the dorsal vessel (heart), esophagus, and prothoracic gland. Dorsal vessel contact allows for systemic distribution of Dilps to peripheral tissues. We are working to determine whether IPCs contact other neurons within the brain, allowing for local Dilp signaling.