bims-proned 2024-02-04 papers

bims-proned

Biomed News

on Proteostasis in neurodegeneration

Issue of 2024–02–04
nine papers selected by
Verena Kohler, Umeå University

Target Identification of a Class of Pyrazolone Protein Aggregation Inhibitor Therapeutics for Amyotrophic Lateral Sclerosis.
Pathological α-synuclein detected by real-time quaking-induced conversion in synucleinopathies.
Effects of α7 nicotinic acetylcholine receptor agonist against α-synuclein-induced neurotoxicity.
Nuclear α-synuclein regulates transcription and affects neuronal differentiation.
Assessing polyglutamine tract aggregation in the nematode Caenorhabditis elegans.
Axonal distribution of mitochondria maintains neuronal autophagy during aging via eIF2β.
Mechanistic modeling of amyloid oligomer and protofibril formation in bovine insulin.
Genetically encoded lysine photocage for spatiotemporal control of TDP-43 nuclear import.
Identification of potential aggregation hotspots on Aβ42 fibrils blocked by the anti-amyloid chaperone-like BRICHOS domain.

ACS Cent Sci. 2024 Jan 24. 10(1): 87-103

Target Identification of a Class of Pyrazolone Protein Aggregation Inhibitor Therapeutics for Amyotrophic Lateral Sclerosis.

Pathum M Weerawarna, Isaac T Schiefer, Pedro Soares, Susan Fox, Richard I Morimoto, Rafael D Melani, Neil L Kelleher, Chi-Hao Luan, Richard B Silverman.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with no cure, and current treatment options are very limited. Previously, we performed a high-throughput screen to identify small molecules that inhibit protein aggregation caused by a mutation in the gene that encodes superoxide dismutase 1 (SOD1), which is responsible for about 25% of familial ALS. This resulted in three hit series of compounds that were optimized over several years to give three compounds that were highly active in a mutant SOD1 ALS model. Here we identify the target of two of the active compounds (6 and 7) with the use of photoaffinity labeling, chemical biology reporters, affinity purification, proteomic analysis, and fluorescent/cellular thermal shift assays. Evidence is provided to demonstrate that these two pyrazolone compounds directly interact with 14-3-3-E and 14-3-3-Q isoforms, which have chaperone activity and are known to interact with mutant SOD1G93A aggregates and become insoluble in the subcellular JUNQ compartment, leading to apoptosis. Because protein aggregation is the hallmark of all neurodegenerative diseases, knowledge of the target compounds that inhibit protein aggregation allows for the design of more effective molecules for the treatment of ALS and possibly other neurodegenerative diseases.

DOI: https://doi.org/10.1021/acscentsci.3c00213
Exp Gerontol. 2024 Jan 25. pii: S0531-5565(24)00008-1. [Epub ahead of print] 112366

Pathological α-synuclein detected by real-time quaking-induced conversion in synucleinopathies.

Juan Huang, Xingxing Yuan, Lin Chen, Binbin Hu, Hui Wang, Ye Wang, Wei Huang.

  synucleinopathies are diseases characterized by the aggregation of α-synuclein (α-syn), which forms fibrils through misfolding and accumulates in a prion-like manner. To detect the presence of these α-syn aggregates in clinical samples, seed amplification assays (SAAs) have been developed. These SAAs are capable of amplifying the α-syn seeds, allowing for their detection. αSyn-SAAs have been reported under the names 'protein misfolding cyclic amplification' (αSyn-PMCA) and 'real-time quaking-induced conversion'α-Syn-RT-QuIC. The α-Syn RT-QuIC, in particular, has been adapted to amplify and detect α-syn aggregates in various biospecimens, including cerebrospinal fluid (CSF), skin, nasal brushing, serum and saliva. The α-syn RT-QuIC assay has demonstrated good sensitivity and specificity in detecting pathological α-syn, particularly in Parkinson's disease (PD) and dementia with Lewy bodies (DLB) cases, with an accuracy rate of up to 80 %. Additionally, differential diagnosis between DLB and PD, as well as PD and multiple system atrophy (MSA), can be achieved by utilizing certain kinetic thioflavin T (ThT) parameters and other parameters. Moreover, the positive detection of α-syn in the prodromal stage of synucleinopathies provides an opportunity for early intervention and management. In summary, the development of the α-syn RT-QuIC assay has greatly contributed to the field of synucleinopathies. Therefore, we review the development of α-syn RT-QuIC assay and describe in detail the recent advancements of α-syn RT-QuIC assay for detecting pathological α-syn in synucleinopathies.

Keywords:  Aggregated α-synuclein; Seed amplification assays; Self-propagation; Synucleinopathies; α-Syn RT-QuIC

DOI:  https://doi.org/10.1016/j.exger.2024.112366
Neurosci Lett. 2024 Jan 26. pii: S0304-3940(24)00031-4. [Epub ahead of print]823 137654

Effects of α7 nicotinic acetylcholine receptor agonist against α-synuclein-induced neurotoxicity.

Shinnosuke Takizawa, Kazuki Ohuchi, Ayaka Fujimaki, Taisei Ito, Takanori Murakami, Hisaka Kurita, Masatoshi Inden.

  The α7 neuronal nicotinic acetylcholine receptor (α7 nAChR) is a potential target for the development of Parkinson's disease (PD) therapeutics. α-Synuclein (α-Syn), a principal component of Lewy bodies (cytoplasmic inclusions), is a major contributor to PD pathophysiology. Previous studies have demonstrated that activating α7 nAChR protects against nigrostriatal dopamine degeneration in acute and chronic PD animal models induced by 6-hydroxydopamine and rotenone, respectively. In the present study, we investigated the effects of PNU282987, a selective α7 nAChR agonist, against α-Syn-induced neurotoxicity in α-SynWT-, α-SynA30P-, and α-SynE46K-N2a cells. PNU282987 exhibited substantial neuroprotection against both wild-type and mutant-type α-Syn-induced toxicity. Furthermore, PNU282987 promoted transcription factor EB activity and reduced intracellular α-Syn protein levels through autophagy induction. These results highlight the therapeutic potential of α7 nAChR activation in diseases characterized by α-Syn aggregation, such as PD.

Keywords:  Autophagy; Neuroprotection; α7 nicotinic acetylcholine receptor

DOI:  https://doi.org/10.1016/j.neulet.2024.137654
FEBS J. 2024 Jan 31.

Nuclear α-synuclein regulates transcription and affects neuronal differentiation.

Andrei Surguchov.

  α-Synuclein is a member of the synuclein family well known for its involvement in Parkinson's disease and other synucleinopathies. Most studies investigate the mechanism of its involvement in pathology within the cell cytoplasm and extracellular space. However, despite a continuing interest in α-synuclein, two questions about this protein remain poorly understood. What is the normal physiological function of α-synuclein, and what does it do in the cell nucleus? A recent article by Takaaki Nakamura and colleagues contains at least a partial answer to both questions. The authors identified previously unknown α-synuclein-interacting proteins in the nucleus and showed that the protein complex containing α-synuclein modulates transcriptional profiles controlling the process of epigenetic alterations and neural differentiation.

Keywords:  arginine methyltransferase 5; epigenomic regulation; histones; transcriptomic analysis; α-synuclein

DOI:  https://doi.org/10.1111/febs.17072
Methods Cell Biol. 2024 ;pii: S0091-679X(22)00144-3. [Epub ahead of print]181 1-15

Assessing polyglutamine tract aggregation in the nematode Caenorhabditis elegans.

Aggeliki Sotiriou, Christina Ploumi, Nikolaos Charmpilas, Nektarios Tavernarakis.

  Proteome integrity is a prerequisite for cellular functionality and organismal viability. Its compromise is considered an inherent part of the aging process and has been associated with the onset of age-related, neurodegenerative pathologies. Although the molecular underpinnings of protein homeostasis (proteostasis) have been extensively studied, several aspects of its regulation remain elusive. The nematode Caenorhabditis elegans has emerged as a versatile, heterologous model organism to study the dynamics of aggregation-prone human proteins in vivo. Here, we describe an experimental pipeline for the analysis of polyglutamine (polyQ) tract aggregation, as a measure of the state of proteostasis, during aging.

Keywords:  Aging; Caenorhabditis elegans; Polyglutamine diseases; Protein aggregation; Proteostasis

DOI:  https://doi.org/10.1016/bs.mcb.2022.09.003
bioRxiv. 2024 Jan 20. pii: 2024.01.20.576435. [Epub ahead of print]

Axonal distribution of mitochondria maintains neuronal autophagy during aging via eIF2β.

Kanako Shinno, Yuri Miura, Koichi M Iijima, Emiko Suzuki, Kanae Ando.

Neuronal aging and neurodegenerative diseases are accompanied by proteostasis collapse, while cellular factors that trigger it are not identified. Impaired mitochondrial transport in the axon is another feature of aging and neurodegenerative diseases. Using Drosophila , we found that genetic depletion of axonal mitochondria causes dysregulation of translation and protein degradation. Axons with mitochondrial depletion showed abnormal protein accumulation, and autophagic defects. Lowering neuronal ATP levels by blocking glycolysis did not reduce autophagy, suggesting that autophagic defects are associated with mitochondrial distribution. We found eIF2β was upregulated by depletion of axonal mitochondria via proteome analysis. Phosphorylation of eIF2α, another subunit of eIF2, was lowered, and global translation was suppressed. Neuronal overexpression of eIF2β phenocopied the autophagic defects and neuronal dysfunctions, and lowering eIF2β expression rescued those perturbations caused by depletion of axonal mitochondria. These results indicate the mitochondria-eIF2β axis maintains proteostasis in the axon, of which disruption may underly the onset and progression of age-related neurodegenerative diseases.
Highlights: Loss of axonal mitochondria impairs autophagy and accumulates proteins in the axonLoss of axonal mitochondria upregulates eIF2β and downregulates p-eIF2αNeuronal upregulation of eIF2β induces autophagic defects and locomotor dysfunctionLowering eIF2β rescues autophagic defects caused by loss of axonal mitochondria.

DOI: https://doi.org/10.1101/2024.01.20.576435
J Mol Biol. 2024 Jan 30. pii: S0022-2836(24)00027-5. [Epub ahead of print] 168461

Mechanistic modeling of amyloid oligomer and protofibril formation in bovine insulin.

Keisuke Yuzu, Hiroshi Imamura, Takuro Nozaki, Yuki Fujii, Shaymaa Mohamed Mohamed Badawy, Ken Morishima, Aya Okuda, Rintaro Inoue, Masaaki Sugiyama, Eri Chatani.

  Early phase of amyloid formation, where prefibrillar aggregates such as oligomers and protofibrils are often observed, is crucial for understanding pathogenesis. However, the detailed mechanisms of their formation have been difficult to elucidate because they tend to form transiently and heterogeneously. Here, we found that bovine insulin protofibril formation proceeds in a monodisperse manner, which allowed us to characterize the detailed early aggregation process by light scattering in combination with thioflavin T (ThT) fluorescence and Fourier transform infrared (FTIR) spectroscopy. The protofibril formation was specific to bovine insulin, whereas no significant aggregation was observed in human insulin. The kinetic analysis combining static and dynamic light scattering data revealed that the protofibril formation process in bovine insulin can be divided into two steps based on fractal dimension. When modeling the experimental data based on Smoluchowski aggregation kinetics, an aggregation scheme consisting of initial fractal aggregation forming spherical oligomers and their subsequent end-to-end association forming protofibrils was clarified. Furthermore, the analysis of temperature and salt concentration dependencies showed that the end-to-end association is the rate-limiting step, involving dehydration. The established model for protofibril formation, wherein oligomers are incorporated as a precursor provides insight into the molecular mechanism by which protein molecules assemble during the early stage of amyloid formation.

Keywords:  amyloid; oligomer; protein aggregation; protein misfolding; protofibril

DOI:  https://doi.org/10.1016/j.jmb.2024.168461
Biophys Chem. 2024 Jan 23. pii: S0301-4622(24)00020-6. [Epub ahead of print]307 107191

Genetically encoded lysine photocage for spatiotemporal control of TDP-43 nuclear import.

Jared A Shadish, Jennifer C Lee.

  Intracellular aggregation of transactive response DNA binding protein of 43 kDa (TDP-43) is a hallmark of neurodegenerative diseases such as amyotrophic lateral sclerosis. While primarily a nuclear protein, TDP-43 translocates to the cytosol during cellular stress. Consequences of cytosolic accumulation of TDP-43 is difficult to evaluate in the absence of exogenous toxins. Here, we demonstrate spatiotemporal control over the nuclear import of TDP-43 by installing a photocage (ortho-nitrobenzyl ester) on a single lysine residue (K84) through amber codon suppression in HEK293T cells. Translocation of this cytosolic construct is photo-triggerable in a dose-dependent manner with 355 nm light. Interestingly, both fluid- and solid-like puncta were found based on fluorescence recovery after photobleaching experiments, similar to what is expected of stress granules and intracellular aggregates, respectively. This optogenetic method is advantageous as it is minimally perturbative and broadly applicable to other studies of protein translocation between cellular compartments.

Keywords:  Amyotrophic lateral sclerosis; FRAP; O-nitrobenzyl-oxycarbonyl-Nε-l-lysine; Optogenetics; Stress granules

DOI:  https://doi.org/10.1016/j.bpc.2024.107191
Nat Commun. 2024 Feb 01. 15(1): 965

Identification of potential aggregation hotspots on Aβ42 fibrils blocked by the anti-amyloid chaperone-like BRICHOS domain.

Rakesh Kumar, Tanguy Le Marchand, Laurène Adam, Raitis Bobrovs, Gefei Chen, Jēkabs Fridmanis, Nina Kronqvist, Henrik Biverstål, Kristaps Jaudzems, Jan Johansson, Guido Pintacuda, Axel Abelein.

Protein misfolding can generate toxic intermediates, which underlies several devastating diseases, such as Alzheimer's disease (AD). The surface of AD-associated amyloid-β peptide (Aβ) fibrils has been suggested to act as a catalyzer for self-replication and generation of potentially toxic species. Specifically tailored molecular chaperones, such as the BRICHOS protein domain, were shown to bind to amyloid fibrils and break this autocatalytic cycle. Here, we identify a site on the Aβ42 fibril surface, consisting of three C-terminal β-strands and particularly the solvent-exposed β-strand stretching from residues 26-28, which is efficiently sensed by a designed variant of Bri2 BRICHOS. Remarkably, while only a low amount of BRICHOS binds to Aβ42 fibrils, fibril-catalyzed nucleation processes are effectively prevented, suggesting that the identified site acts as a catalytic aggregation hotspot, which can specifically be blocked by BRICHOS. Hence, these findings provide an understanding how toxic nucleation events can be targeted by molecular chaperones.

DOI: https://doi.org/10.1038/s41467-024-45192-4