Stem cell-specific ecdysone signaling regulates the development and function of aDrosophilasleep homeostat

Abstract

Complex behaviors arise from neural circuits that are assembled from diverse cell types. Sleep is a conserved and essential behavior, yet little is known regarding how the nervous system generates neuron types of the sleep-wake circuit. Here, we focus on the specification ofDrosophilasleep-promoting neurons—long-field tangential input neurons that project to the dorsal layers of the fan-shaped body neuropil in the central complex (CX). We use lineage analysis and genetic birth dating to identify two bilateral Type II neural stem cells that generate these dorsal fan-shaped body (dFB) neurons. We show that adult dFB neurons express Ecdysone-induced protein E93, and loss of Ecdysone signaling or E93 in Type II NSCs results in the misspecification of the adult dFB neurons. Finally, we show that E93 knockdown in Type II NSCs affects adult sleep behavior. Our results provide insight into how extrinsic hormonal signaling acts on NSCs to generate neuronal diversity required for adult sleep behavior. These findings suggest that some adult sleep disorders might derive from defects in stem cell-specific temporal neurodevelopmental programs.

Seven-up acts in neuroblasts to specify adult central complex neuron identity and initiate neuroblast decommissioning

“…This is supported by recent work reporting knockdown of Imp levels in T2NB lineages results in altered CX neurons; however, it is unclear if this is due to the role of Imp at the NB or INP level (Hamid et al, 2023). Additionally, loss of T2NB temporal factors EcR and E93 are required for specifying the CX neuron subtype dFB neurons (Wani et al, 2023). Our data do not distinguish between a model for a temporal transcription factor cascade and/or temporal gradients.…”