Ecdysone acts through cortex glia to regulate sleep in Drosophila

Area of Science:

• Neuroendocrinology
• Molecular Biology
• Behavioral Neuroscience

Background:

• Steroid hormones, derived from cholesterol, are lipid-soluble signaling molecules.
• Nuclear hormone receptors (NHRs) function as transcription factors, mediating hormone action.
• NHRs are potential regulators of complex behaviors, including sleep.

Purpose of the Study:

• To investigate the role of NHRs in regulating sleep:wake cycles in Drosophila.
• To identify specific NHRs and their cellular targets involved in sleep regulation.

Main Methods:

• Knockdown of 18 conserved NHRs in adult Drosophila.
• Localization of ecdysone receptor (EcR) in brain glia.
• Functional screening of glial subtypes for EcR activity.
• Analysis of lipid droplets (LDs) in glia.
• Assessment of sleep in mutant flies with altered lipid metabolism.

Main Results:

• Ecdysone receptor (EcR) and Eip75B (E75) act in glia to regulate sleep rhythm and amount.
• Ecdysone appears to be a long-distance signal, with increased brain entry at night.
• EcR is localized to cortex glia, which are involved in lipid metabolism.
• Ecdysone treatment mobilizes LDs; glial EcR knockdown increases LDs.
• Sleep effects of ecdysone are reduced in lipid-deficient mutant flies.

Conclusions:

• Ecdysone acts as a systemic factor modulating sleep through lipid metabolism in cortex glia.
• This study identifies a novel role for steroid hormone signaling in glial regulation of sleep.
• The findings highlight the interplay between systemic hormones, brain lipid metabolism, and sleep behavior.