Gel-like inclusions of C-terminal fragments of TDP-43 sequester stalled proteasomes in neurons

Riemenschneider, Henrick; Guo, Qiang; Bader, Jakob; Frottin, Frederic; Farny, Daniel; Kleinberger, Gernot; Haass, Christian; Mann, Matthias; Hartl, F. Ulrich; Baumeister, Wolfgang; Hipp, Mark S.; Meissner, Felix; Fernandez-Busnadiego, Ruben und Edbauer, Dieter (2022): Gel-like inclusions of C-terminal fragments of TDP-43 sequester stalled proteasomes in neurons. In: EMBO Reports, Bd. 23, Nr. 6, e53890

Abstract

Aggregation of the multifunctional RNA-binding protein TDP-43 defines large subgroups of amyotrophic lateral sclerosis and fronto-temporal dementia and correlates with neurodegeneration in both diseases. In disease, characteristic C-terminal fragments of similar to 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 265 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 pathophysiological relevance of proteasome dysfunction in ALS/FTD.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Medizin ; Medizin > Munich Cluster for Systems Neurology (SyNergy)
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• ISSN: 1469-221X
• Sprache: Englisch
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 390729940
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 390857198