TY - JOUR
T1 - Gel-like inclusions of C-terminal fragments of TDP-43 sequester stalled proteasomes in neurons
AU - Riemenschneider, Henrick
AU - Guo, Qiang
AU - Bader, Jakob
AU - Frottin, Frédéric
AU - Farny, Daniel
AU - Kleinberger, Gernot
AU - Haass, Christian
AU - Mann, Matthias
AU - Hartl, F. Ulrich
AU - Baumeister, Wolfgang
AU - Hipp, Mark S.
AU - Meissner, Felix
AU - Fernández-Busnadiego, Rubén
AU - Edbauer, Dieter
N1 - Funding Information:
We thank Philipp Erdmann, Günter Pfeifer, Jürgen Plitzko and Miroslava Schaffer for electron microscopy support. We thank Ina Wendland and the Imaging Facility of the Max Planck Institute of Biochemistry for technical support. We thank Christian Behrends, Mareike Czuppa, Dorothee Dormann, Bettina Schmid, Ali Rezaei and Qihui Zhou for critical comments to the manuscript. This work was supported by NOMIS foundation (D.E.). M.S.H., F.U.H., Q.G., W.B., and R.F.‐B. have received funding from the European Commission (FP7 GA ERC‐2012‐SyG_318987‐ToPAG). D.E., C.H., M.S.H., F.U.H., and R.F.‐B. acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through Germany’s Excellence Strategy ‐ EXC 2067/1‐ 390729940 (R.F.‐B.) and EXC 2145 – 390857198 (C.H., F.U.H., M.S.H., and D.E.). The synopsis image has been created with BioRender (adapted from “Ubiquitin Proteasome System,” by BioRender.com (2021), retrieved from https://app.biorender.com/biorender‐templates ). Open Access funding enabled and organized by Projekt DEAL.
Publisher Copyright:
© 2022 The Authors. Published under the terms of the CC BY 4.0 license.
PY - 2022/6
Y1 - 2022/6
N2 - 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.
AB - 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.
KW - ALS
KW - neurodegeneration
KW - phase separation
KW - proteasome
KW - TDP-43
U2 - 10.15252/embr.202153890
DO - 10.15252/embr.202153890
M3 - Article
C2 - 35438230
AN - SCOPUS:85129071363
SN - 1469-221X
VL - 23
JO - Embo Reports
JF - Embo Reports
IS - 6
M1 - e53890
ER -