Structural insights into the multi-determinant aggregation of TDP-43 in motor neuron-like cells.
TDP-43 is aggregated in patients with ALS and FLTD through mechanisms still incompletely understood. Since aggregation in the cytosol is most probably responsible for the delocalization and loss of proper RNA-binding function of TDP-43 in the nucleus, interception of the formation of aggregates may represent a useful therapeutic option. In this study, we investigated the relative importance of the N-terminal and C-terminal moieties of TDP-43 in the aggregation process and the weight of each of the six cysteine residues in determining unfolding and aggregation of the different domains. We report that cytoplasmic inclusions formed by WT and mutant TDP-43 in motor neuron-like NSC34 cells are redox-sensitive only in part, and contain at least two components, i.e. oligomers and large aggregates, that are made of different molecular species. The two N-terminal cysteine residues contribute to the seeding for the first step in oligomerization, which is then accomplished by mechanisms depending on the four cysteines in the RNA-recognition motifs. Cysteine-independent large aggregates contain unfolded isoforms of the protein, held together by unspecific hydrophobic interactions. Interestingly, truncated isoforms are entrapped exclusively in oligomers. Ab initio modeling of TDP-43 structure, molecular dynamics and molecular docking analysis indicate a differential accessibility of cysteine residues that contributes to aggregation propensity. We propose a model of TDP-43 aggregation involving cysteine-dependent and cysteine-independent stages that may constitute a starting point to devise strategies counteracting the formation of inclusions in TDP-43 proteinopathies.
Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy; Fondazione Santa Lucia IRCCS, c/o CERC, 00143 Rome, Italy.
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Bozzo
Fondazione Santa Lucia IRCCS, c/o CERC, 00143 Rome, Italy.
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Salvatori
Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy; Interuniversity Consortium, National Institute of Biostructure and Biosystem (INBB), Italy.
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Iacovelli
Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy; Fondazione Santa Lucia IRCCS, c/o CERC, 00143 Rome, Italy.
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Mirra
Institute of Translational Pharmacology, CNR, 00133 Rome, Italy.
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Rossi
Fondazione Santa Lucia IRCCS, c/o CERC, 00143 Rome, Italy; Institute of Translational Pharmacology, CNR, 00133 Rome, Italy.
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Cozzolino
Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy; Interuniversity Consortium, National Institute of Biostructure and Biosystem (INBB), Italy.
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Falconi
Fondazione Santa Lucia IRCCS, c/o CERC, 00143 Rome, Italy; Institute for Cell Biology and Neurobiology, CNR, c/o CERC, 00143 Rome, Italy. Electronic address: cvalle@ibc.cnr.it.
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Valle
Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy; Fondazione Santa Lucia IRCCS, c/o CERC, 00143 Rome, Italy. Electronic address: carri@bio.uniroma2.it.
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Carrì
D000690:Amyotrophic Lateral Sclerosis / Q000378:metabolism*; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D002479:Inclusion Bodies / Q000378:metabolism*; D051379:Mice; D062105:Molecular Docking Simulation / Q000379:methods; D056004:Molecular Dynamics Simulation; D009046:Motor Neurons / Q000378:metabolism*
D004268:DNA-Binding Proteins; C578077:Tardbp protein, mouse
ALS; Amyotrophic lateral sclerosis; Cysteine; Large aggregates; N-terminal domain; Neurodegeneration; Oligomers; Protein aggregation; TDP-43