Abstract
Amyotrophic lateral sclerosis (ALS) is a synaptopathy accompanied by the presence of cytoplasmic aggregates containing TDP-43, an RNA-binding protein linked to ∼97% of ALS cases. Using a Drosophila model of ALS, we show that TDP-43 overexpression (OE) in motor neurons results in decreased expression of the Hsc70-4 chaperone at the neuromuscular junction (NMJ). Mechanistically, mutant TDP-43 sequesters hsc70-4 mRNA and impairs its translation. Expression of the Hsc70-4 ortholog, HSPA8, is also reduced in primary motor neurons and NMJs of mice expressing mutant TDP-43. Electrophysiology, imaging, and genetic interaction experiments reveal TDP-43-dependent defects in synaptic vesicle endocytosis. These deficits can be partially restored by OE of Hsc70-4, cysteine-string protein (Csp), or dynamin. This suggests that TDP-43 toxicity results in part from impaired activity of the synaptic CSP/Hsc70 chaperone complex impacting dynamin function. Finally, Hsc70-4/HSPA8 expression is also post-transcriptionally reduced in fly and human induced pluripotent stem cell (iPSC) C9orf72 models, suggesting a common disease pathomechanism. Amyotrophic lateral sclerosis (ALS) is a fatal disease characterized by synaptic failure. Coyne et al. show that in multiple models of ALS, ranging from Drosophila to mice to patient-derived motor neurons, deficits in synaptic vesicle cycling can be explained by dysregulation of the Hsc70-4/HSPA8 chaperone.
Original language | English (US) |
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Pages (from-to) | 110-125 |
Number of pages | 16 |
Journal | Cell Reports |
Volume | 21 |
Issue number | 1 |
DOIs | |
State | Published - Oct 3 2017 |
Keywords
- C9orf72
- Drosophila
- RNA processing
- TDP-43
- amyotrophic lateral sclerosis
- endocytosis
- iPSC
- neuromuscular junction
- synaptic vesicle cycle
- translation
ASJC Scopus subject areas
- General Biochemistry, Genetics and Molecular Biology