Hormonal control of postmitotic neuronal identity

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• The Drosophila central complex coordinates complex behaviors via precisely wired neuronal circuits.
• Dorsal fan-shaped body (dFB) neurons regulate sleep, feeding, and energy homeostasis, but their subtype specification and maintenance are poorly understood.
• The role of developmental transcription factors in maintaining neuronal identity post-mitosis is unclear.

Purpose of the Study:

• To investigate the developmental origin and post-mitotic regulation of neuronal identity in specific dFB neuron subtypes (84C10 driver).
• To determine the role of the transcription factor E93 in maintaining the survival, connectivity, and function of these dFB neurons.
• To understand how developmental programs are repurposed for adult behavioral circuit function.

Main Methods:

• Lineage tracing, clonal analysis, and birth-dating to determine the developmental origin of 84C10 dFB neurons.
• Analysis of the temporal expression window of dFB neuron generation.
• Selective post-mitotic knockdown of E93 in mature 84C10 neurons to assess its function.

Main Results:

• 84C10 dFB neurons originate from DL1 type II neural stem cells during a late larval temporal window (after ~48 h ALH).
• These neurons maintain E93 expression into adulthood.
• Post-mitotic knockdown of E93 leads to neuronal loss, aberrant axonal projections, reduced vGLUT expression, and impaired metabolic adaptation to high-sugar diets.

Conclusions:

• The late temporal transcription factor E93 is retained post-mitotically to ensure the survival, layer-specific connectivity, and neurotransmitter identity of behaviorally relevant dFB neurons.
• Developmental transcription factors can be repurposed to sustain the long-term function of adult neural circuits.
• E93 plays a critical role in maintaining neuronal homeostasis and metabolic regulation in adult Drosophila.