Developmentally programmed remodeling of the Drosophila olfactory circuit

Area of Science:

• Neuroscience
• Developmental Biology
• Insect Models

Background:

• Neural circuits undergo significant remodeling after initial formation.
• The coordination mechanisms of synaptically connected neuron reorganization remain largely unknown.
• Drosophila olfactory projection neurons (PNs) are crucial for olfactory information processing.

Purpose of the Study:

• To investigate the remodeling processes of embryonic-born PNs in Drosophila.
• To determine if synaptically connected neurons coordinate their structural reorganization during metamorphosis.
• To elucidate the molecular mechanisms underlying PN and mushroom body (MB) gamma neuron pruning.

Main Methods:

• Developmental tracing of embryonic-born PNs.
• Analysis of PN innervation patterns in larval and adult stages.
• Electron microscopy to examine synaptic structures.
• Genetic analysis of ecdysone signaling in pruning.

Main Results:

• Embryonic-born PNs persist from larval to adult olfactory circuits, with distinct innervation patterns.
• PNs undergo stereotyped pruning of dendrites and axon terminals during metamorphosis.
• Synaptic profiles between PNs and MB gamma neurons are engulfed by glia.
• PN pruning, similar to MB gamma neurons, requires cell-autonomous ecdysone signaling.

Conclusions:

• Embryonic-born PNs are dynamically remodeled during Drosophila development.
• PNs and their synaptic partners prune independently but are coordinated by developmental timing and hormonal cues.
• Ecdysone acts cell-autonomously to regulate pruning in both PNs and MB gamma neurons, ensuring circuit reorganization.