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New Study Links Motor Neuron Size to ALS Vulnerability Through Proteostasis Burden

Single-cell imaging in transparent zebrafish pinpoints a constant protein-clearance load in the largest spinal neurons most prone to degeneration.

Overview

  • A Nature Communications paper from Kazuhide Asakawa’s group reports that large spinal motor neurons maintain persistently elevated autophagy, proteasome activity, and unfolded protein response.
  • Using single-cell–resolution measurements, the team found higher degradation activity in large spinal neurons than in smaller spinal neurons and in ALS-resistant ocular motor neurons.
  • Genetic inactivation of TDP-43 further accelerated autophagy and proteasome-mediated degradation, intensifying cellular stress in the large, ALS-vulnerable population.
  • The accelerated degradation initially supported axon outgrowth but became unsustainable over time, aligning with selective motor neuron degeneration observed in ALS.
  • The authors suggest reducing the intrinsic degradation burden as a therapeutic strategy, while noting the results are preclinical in zebrafish and need validation in mammalian models.