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Updated: Jun 4, 2025
Morphological and Functional Evaluation of Axons and their Synapses during Axon Death in Drosophila melanogaster
Published on: March 16, 2020
DLK-dependent axonal mitochondrial fission drives degeneration after axotomy
Jorge Gómez-Deza1, Matthew Nebiyou1, Mor R Alkaslasi1
1Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
Abstract:
Currently there are no effective treatments for an array of neurodegenerative disorders to a large part because cell-based models fail to recapitulate disease. Here we develop a reproducible human iPSC-based model where laser axotomy causes retrograde axon degeneration leading to neuronal cell death. Time-lapse confocal imaging revealed that damage triggers an apoptotic wave of mitochondrial fission proceeding from the site of injury to the soma. We demonstrate that this apoptotic wave is locally initiated in the axon by dual leucine zipper kinase (DLK). We find that mitochondrial fission and resultant cell death are entirely dependent on phosphorylation of dynamin related protein 1 (DRP1) downstream of DLK, revealing a mechanism by which DLK can drive apoptosis. Importantly, we show that CRISPR mediated Drp1 depletion protects mouse retinal ganglion neurons from degeneration after optic nerve crush. Our results provide a platform for studying degeneration of human neurons, pinpoint key early events in damage related neural death and provide potential focus for therapeutic intervention.
Insights
Researchers developed a human iPSC model of neurodegeneration. They found dual leucine zipper kinase (DLK) initiates an apoptotic wave via dynamin-related protein 1 (DRP1) phosphorylation, leading to neuronal death.
Area of Science:
- Neuroscience
- Cell Biology
- Genetics
Background:
- Neurodegenerative disorders lack effective treatments due to inadequate disease models.
- Current models fail to accurately recapitulate human neuronal degeneration.
Purpose of the Study:
- To develop a reproducible human induced pluripotent stem cell (iPSC)-based model for studying neurodegeneration.
- To identify key molecular mechanisms driving neuronal cell death after injury.
Main Methods:
- Laser axotomy was used to induce retrograde axon degeneration in human iPSC-derived neurons.
- Time-lapse confocal imaging tracked cellular events following injury.
- CRISPR-Cas9 technology was employed to deplete dynamin-related protein 1 (DRP1).
Main Results:
- Laser axotomy triggered an apoptotic wave of mitochondrial fission from the injury site to the soma.
- Dual leucine zipper kinase (DLK) was identified as the initiator of this apoptotic wave in the axon.
- Mitochondrial fission and cell death were dependent on DLK-mediated phosphorylation of DRP1.
- CRISPR-mediated DRP1 depletion protected mouse retinal ganglion neurons from degeneration after optic nerve crush.
Conclusions:
- The developed human iPSC model provides a platform for studying neurodegeneration.
- DLK-mediated DRP1 phosphorylation is a critical mechanism in damage-induced neuronal apoptosis.
- Targeting DLK or DRP1 may offer therapeutic strategies for neurodegenerative diseases.
