Gel-like inclusions of C-terminal fragments of TDP-43 sequester stalled proteasomes in neurons
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Aggregation of the multifunctional RNA-binding protein TDP-43 defines large subgroups of amyotrophic lateral sclerosis and frontotemporal dementia and correlates with neurodegeneration in both diseases. In disease, characteristic C-terminal fragments of ~25 kDa ("TDP-25") accumulate in cytoplasmic inclusions. Here, we analyze gain-of-function mechanisms of TDP-25 combining cryo-electron tomography, proteomics, and functional assays. In neurons, cytoplasmic TDP-25 inclusions are amorphous, and photobleaching experiments reveal gel-like biophysical properties that are less dynamic than nuclear TDP-43. Compared with full-length TDP-43, the TDP-25 interactome is depleted of low-complexity domain proteins. TDP-25 inclusions are enriched in 26S proteasomes adopting exclusively substrate-processing conformations, suggesting that inclusions sequester proteasomes, which are largely stalled and no longer undergo the cyclic conformational changes required for proteolytic activity. Reporter assays confirm that TDP-25 impairs proteostasis, and this inhibitory function is enhanced by ALS-causing TDP-43 mutations. These findings support a patho-physiological relevance of proteasome dysfunction in ALS/FTD.
Original language | English |
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Article number | e53890 |
Journal | EMBO Reports |
Volume | 23 |
Issue number | 6 |
ISSN | 1469-221X |
DOIs | |
Publication status | Published - 2022 |
Externally published | Yes |
Bibliographical note
© 2022 The Authors. Published under the terms of the CC BY 4.0 license.
- Amyotrophic Lateral Sclerosis/genetics, DNA-Binding Proteins/genetics, Frontotemporal Dementia/genetics, Humans, Inclusion Bodies/metabolism, Neurons/metabolism, Peptide Fragments/genetics, Proteasome Endopeptidase Complex/metabolism
Research areas
ID: 331591188