Dynamic modulation of the motor neuron translatome during developmental synapse elimination

Area of Science:

• Neuroscience
• Developmental Biology
• Molecular Biology

Background:

• Neuromuscular junction (NMJ) development involves synapse elimination, where excess axon inputs are pruned to ensure single innervation per muscle fiber.
• This critical process refines motor circuitry during early postnatal development.

Purpose of the Study:

• To investigate the molecular pathways governing synapse elimination at the NMJ.
• To characterize cell type-specific changes in motor neuron gene expression during this developmental period.

Main Methods:

• Utilized a ChAT-RiboTag mouse model to isolate ribosome-bound mRNAs from motor neurons.
• Employed translating ribosome affinity purification followed by RNA sequencing (TRAP-seq) to analyze the motor neuron translatome.
• Performed bioinformatic analysis to identify temporal transcriptomic changes and therapeutic targets.

Main Results:

• Revealed dynamic, time-specific changes in the motor neuron translatome during the first two weeks of postnatal life.
• Observed that these translational changes were largely independent of transcriptional alterations.
• Identified specific transcript clusters associated with neural metabolism that, when targeted by small molecules, accelerated synapse elimination in vivo.

Conclusions:

• Provides a cell type-specific temporal map of motor neuron translatome modifications during synapse elimination.
• Demonstrates that targeting neural metabolism pathways can modulate the rate of synapse elimination.
• Highlights the importance of post-transcriptional regulation in refining neuromuscular circuitry.