2025-07-16 ミシガン大学
Graphic abstract of the study Pyruvate kinase deficiency links metabolic perturbations to neurodegeneration and axonal protection. Image credit: © 2025 The Author(s), CC 4.0 BY license
<関連情報>
- https://news.umich.edu/metabolism-may-unlock-the-secret-to-a-deeper-understanding-of-neurodegeneration/
- https://www.sciencedirect.com/science/article/pii/S2212877825000948?via%3Dihub
ピルビン酸キナーゼ欠損は代謝擾乱を神経変性と軸索保護に関連付ける Pyruvate kinase deficiency links metabolic perturbations to neurodegeneration and axonal protection
Thomas J Waller, Catherine A Collins, Monica Dus
Molecular Metabolism Available online: 10 June 2025
DOI:https://doi.org/10.1016/j.molmet.2025.102187
Highlights
- Loss of pyruvate kinase (PyK) induces progressive axon degeneration and synapse loss in motor neurons.
- The synaptic degeneration caused by PyK disruption is dependent on DLK and SARM1.
- PyK loss delays injury-induced axon degeneration (Wallerian degeneration).
- Delayed Wallerian degeneration of PyK-deficient axons is partially dependent on DLK and Fos.
- SARM1 axonal localization is diminished following PyK loss and its overexpression restores Wallerian degeneration speed.
Abstract
Objective
Metabolic disruption is a central feature to many neurodegenerative diseases. Despite this, many gaps exist in our understanding of how these perturbations link to the mechanisms of neural disease. In this study, we sought to understand how genetically-controlled, cell-specific loss of pyruvate kinase (PyK) impacts motor neuron synaptic integrity and how the canonical neurodegenerative proteins DLK and SARM1 respond to this break in homeostasis.
Methods
This study made use of the genetically-tractable Drosophila melanogaster to cell-specifically express proteins (via the GAL4/UAS binary system), knockdown gene transcripts (via RNA interference), and knockout gene loci (via guide RNA-directed Cas9). Synaptic and axonal degeneration were measured through immunohistochemistry, microscopy, and blinded scoring of fly larvae at both early and later 3rd instar stages to test for progressive phenotypes. Nervous system injury through a physical nerve crush assay was used to assay functional outcomes of protective stress responses.
Results
We found that knockdown or knockout of PyK results in progressive axonal and synaptic degeneration, dependent on signaling through DLK and SARM1. This degeneration is preceded by nuclear transcriptional activation by DLK and the downstream AP-1 transcription factor Fos. We also found evidence of a neuroprotective response through injury of PyK-deficient axons (before progressive degeneration has occurred), which results in delayed Wallerian degeneration. This delay shows dependence on DLK and Fos, and coincides with reduced axonal localization of SARM1 whose overexpression fully restores degeneration speed.
Conclusions
These data support a rheostat model of DLK signaling that both promotes and inhibits axon degeneration in response to metabolic disruption. This rheostat likely converges on regulation of SARM1, which is required for the progressive synapse loss following PyK, but also abolishes the protective delay in injury-induced Wallerian degeneration when overexpressed. Overall, we conclude that metabolic signaling through PyK is essential for the integrity of motor neuron axons and synapses, and that its disruption activates both neurodegenerative and neuroprotective mechanisms
