bims-proned 2025-07-20 papers

bims-proned

Biomed News

on Proteostasis in neurodegeneration

Issue of 2025–07–20
24 papers selected by
Verena Kohler, Umeå University

Amyloid-β modulates the phase separation and aggregation of α-synuclein.
Photochemically synthesized gold nanoparticles conjugated with Boswellic acid inhibit alpha synuclein aggregation and delay fibrillation kinetics.
Phenolic Acids Commonly Found in Natural Products Modulate Protein Aggregation in Caenorhabditis elegans Neurodegeneration Models.
Capturing α-synuclein aggregation interactors using UltraID-LIPA.
UBQLN2 in neurodegenerative disease: mechanistic insights and emerging therapeutic potential.
Protein and RNA chaperones.
Human TDP-43 overexpression in zebrafish motor neurons triggers MND-like phenotypes through gain-of-function mechanism.
Scouring the human Hsp70 network uncovers diverse chaperone safeguards buffering TDP-43 toxicity.
Investigating the Stability, Flexibility, and Phase Separation Properties of H46R and H80R Disease Mutants of SOD1: Insights into ALS Pathogenesis.
DCPS modulates TDP-43 mediated neurodegeneration through P-body regulation.
TDP-43 toxic gain of function links ALS, FTD and Alzheimer's Disease through splicing dysregulation.
Random peptide mixtures of tryptophan and lysine suppress the aggregation of a cancer-related mutant of the Axin protein.
A genetically encoded selection for amyloid-β oligomer binders.
Pathological α-Synuclein Perturbs Nuclear Integrity.
Single particle dynamics of protein aggregation and disaggregation in the presence of the sHsp proteins IbpAB.
Anti-Amyloid Aggregation Effects of Gobaishi (Galla chinensis) and Its Active Constituents.
TNF-α-NF-κB activation through pathological α-Synuclein disrupts the BBB and exacerbates axonopathy.
Polyglycine-mediated aggregation of FAM98B disrupts tRNA processing in GGC repeat disorders.
Tau Clearance Reverses Neuronal Dysfunction in Both Young and Aged C. elegans.
Microtubule-associated protein 4 forms aggregates consisting of helical filaments.
The Emerging Role of the Molecular Chaperone Clusterin in Parkinson's Disease.
Impact of sex and glial tau expression on heat shock protein induction in a Drosophila model of tauopathy.
Accumulation of LRRK2-associated phospho-Rab12 degenerative lysosomes in tauopathies.
Lysosomal Protease-Mediated APP Degradation is pH-Dependent, Mutation-Sensitive, and Facilitates Tau Proteolysis.

Proc Natl Acad Sci U S A. 2025 Jul 22. 122(29): e2501987122

Amyloid-β modulates the phase separation and aggregation of α-synuclein.

Alexander Röntgen, Zenon Toprakcioglu, Owen M Morris, Michele Vendruscolo.

  The aggregation of amyloid-β (Aβ) and α-synuclein (αSyn) into insoluble proteinaceous deposits is a hallmark of Alzheimer's and Parkinson's diseases. Recent evidence suggests that these amyloidogenic proteins act in synergy, with their coaggregation frequently observed in these disorders. In this study, we investigate the interaction of Aβ and αSyn using various biophysical tools. In particular, we explore the cocondensation of Aβ with αSyn, elucidating the pathways through which Aβ modulates αSyn phase separation. We studied different variants of Aβ, focusing on the most prominent species, namely Aβ42 and Aβ40. We found that Aβ42 and Aβ40 have fundamentally different mechanistic effects on the kinetics of αSyn condensation. Aβ42 initially forms large aggregates that act as heterogeneous nucleation sites which initiate the phase separation of αSyn. In contrast, Aβ40 is sequestered into αSyn condensates where it accelerates the liquid-to-solid transition of αSyn into amyloid aggregates. All other Aβ variants we probed fell into one of these two mechanistic pathways, with Aβ37, Aβ39, and Aβ35-25 exhibiting similar behavior to Aβ40, whereas Aβ43 triggered nucleation processes similar to Aβ42. Given the complexity behind amyloid formation, it is key to understand how molecular partners can interact with one another. Our results thus illustrate the extreme sensitivity of protein mixtures and shed light on some of the mechanisms involved in the cocondensation and aggregation of Aβ with αSyn.

Keywords:  chemical kinetics; liquid-liquid phase separation; protein aggregation; protein condensation

DOI:  https://doi.org/10.1073/pnas.2501987122
Sci Rep. 2025 Jul 17. 15(1): 25886

Photochemically synthesized gold nanoparticles conjugated with Boswellic acid inhibit alpha synuclein aggregation and delay fibrillation kinetics.

Masoumeh Gharb, Farima Mozafari, Payam Arghavani, Ali Akbar Saboury, Gholamhossein Riazi.

  Neurodegenerative disorders are characterised by the gradual degeneration and death of neurons in distinct brain regions. In Parkinson's disease (PD), a key pathological hallmark is the aggregation of misfolded α-synuclein (α-Syn) into neurotoxic fibrils. Although natural products such as Boswellic acids (BAs) from Boswellia serrata exhibit therapeutic potential, their clinical application is limited by poor pharmacokinetic properties. To address this, we investigated BAs conjugated to gold nanoparticles (GNPs) to enhance bioavailability and therapeutic potential. Both covalent and noncovalent β-Boswellic acid to GNPs (GNP-BA) conjugates were synthesized and evaluated for their effects on α-Syn fibrillation in vitro. The spherical GNPs (< 32 nm) were successfully characterized via high-resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FESEM). Conjugation of BA was confirmed by UV-Visible and Fourier-transform infrared (FTIR) spectroscopies. Thioflavin T (ThT) assay and atomic force microscopy (AFM) analyses demonstrated that noncovalently bound GNP-BAs significantly inhibited α-Syn fibril formation. Our findings reveal that both synthesis and conjugation strategies significantly influence the anti-aggregation behaviour of GNPs. Notably, photochemically synthesised GNP-BAs exhibited superior biofunctionality. This work introduces a dual-functional nanoplatform that enhances BA bioavailability while effectively inhibiting α-Syn aggregation, offering translational potential for real-world therapeutic development in PD and related synucleinopathies.

Keywords:  Boswellic acids; Gold nanoparticle; Protein fibrillation; α-synuclein

DOI:  https://doi.org/10.1038/s41598-025-11107-6
ACS Omega. 2025 Jul 08. 10(26): 27861-27868

Phenolic Acids Commonly Found in Natural Products Modulate Protein Aggregation in Caenorhabditis elegans Neurodegeneration Models.

Xareni Valle-Jiménez, Ixchel Osorio-Paz, Silvestre Alavez.

Abnormal protein accumulation is frequently associated with the gradual degeneration of the central nervous system, which results in the development and progression of several neurodegenerative diseases (NDs). Since the incidence of ND is on the rise, their effects represent a substantial psychological and economic burden. As we advance in understanding human aging mechanisms, it is desirable to accelerate the discovery of molecules that can modulate human aging and perhaps postpone the onset of age-related disease. Therefore, uncovering compounds that can prevent the formation of protein aggregates should be a priority in the aging research field. Phenolic acids are organic compounds found in many natural products, such as vegetables and fruits. These compounds have been shown to have potential neuroprotective benefits. However, its effects on protein aggregation related to neurodegeneration processes are still not clear. In this study, we thoroughly explored the ability of four phenolic acids: caffeic (CA), p-coumaric (p-CoA), ferulic (FA), and gallic (GA) acids to prevent protein aggregation in three models of human neurodegeneration, such as Alzheimer's disease, Huntington's disease, and Parkinson's disease. We found that high CA, p-CoA, FA, and GA concentrations reduce the β-amyloid-aggregation-induced paralysis phenotype by up to 32%. Also, high CA, FA, and GA concentrations decreased paralysis percentage and polyQ aggregations by 25, 26, and 47%, respectively. Interestingly, high concentrations of p-CoA reduced polyQ aggregation but not the percentage of protein aggregation-induced paralysis. Additionally, only high concentrations of CA, along with lower concentrations of FA and GA, demonstrated the potential to reduce α-synuclein aggregation. Our findings suggest that CA, FA, and GA are worthy candidates for acting as neuroprotectors in mammals.

DOI: https://doi.org/10.1021/acsomega.5c00695
Trends Neurosci. 2025 Jul 10. pii: S0166-2236(25)00144-4. [Epub ahead of print]

Capturing α-synuclein aggregation interactors using UltraID-LIPA.

Kreesan Reddy, Birger Victor Dieriks.

  Teixeira et al. present UltraID-light-inducible protein aggregation (UltraID-LIPA), a technique that combines optogenetic induction of α-synuclein aggregation with proximity-based proteomics. This system enables high-resolution capture of early aggregation events in live cells and implicates known and novel endolysosomal proteins, offering a robust framework for dissecting early pathogenic mechanisms in synucleinopathies and guiding future innovations.

Keywords:  Parkinson’s disease; disease heterogeneity; protein interactome; protein misfolding; strain diversity; synucleinopathies

DOI:  https://doi.org/10.1016/j.tins.2025.07.002
Biochem Soc Trans. 2025 Jul 14. pii: BST20253053. [Epub ahead of print]

UBQLN2 in neurodegenerative disease: mechanistic insights and emerging therapeutic potential.

Autumn M Matthews, Alexandra M Whiteley.

  Ubiquilins (UBQLNs) regulate cellular protein turnover by shuttling proteins, or 'clients', to the proteasome or autophagy pathways for degradation. Of the five different UBQLN genes in humans, UBQLN2 is the most highly expressed in the nervous system and muscle tissue and has been linked to multiple neurodegenerative diseases. In particular, point mutations of UBQLN2 cause an X-linked, dominant form of amyotrophic lateral sclerosis (ALS), ALS with frontotemporal dementia (ALS/FTD), or FTD. Failed protein degradation is a hallmark of many neurodegenerative diseases, including ALS and FTD; however, it is not clear exactly how ALS/FTD-associated UBQLN2 mutations contribute to pathogenesis. Recent studies have revealed the complexity of UBQLN2 biology and allow deeper understanding as to how UBQLN2 dysfunction may contribute to neurodegenerative disease. UBQLN2 is necessary for mitochondrial protein degradation and for regulating mitochondrial turnover, both of which are essential for motor neurons and have been implicated in the pathogenesis of ALS. Stress granule (SG) formation and regulation are also affected by UBQLN2 mutations, and their dysregulation may contribute to the toxic protein aggregation and SG changes observed in neurodegenerative disease. Finally, there are compelling links connecting UBQLN2 dysfunction with changes to downstream neuronal morphology, function, and behavior. This review will detail the emerging consensus on how UBQLN2 protects against neurodegenerative disease and will provide insights into potential therapeutic approaches.

Keywords:  ALS; PEG10; Ubiquilin 2; mitochondria; neurodegenerative disease; protein degradation; stress granules

DOI:  https://doi.org/10.1042/BST20253053
Mol Aspects Med. 2025 Jul 14. pii: S0098-2997(25)00048-2. [Epub ahead of print]104 101384

Protein and RNA chaperones.

Bikash R Sahoo, James Ca Bardwell.

Cells preserve macromolecular homeostasis by utilizing molecular chaperones that prevent aggregation or promote correct folding of protein and RNA. Here we discuss non-traditional proteinaceous chaperones like RNA-binding chaperones that work by modulating RNA structure, preventing aberrant interactions, and regulating intracellular granule dynamics. We also discuss the chaperone functions of other macromolecules such as nucleic acids, and in particular G-quadruplexes, which are very effective at preventing protein aggregation and accelerating protein folding. These chaperones are particularly important in G-quadruplex linked amyloid aggregation and repeat-expansion diseases such as Parkinson's disease and amyotrophic lateral sclerosis, where RNA aggregation and misfolded protein accumulation co-occur. By comparing protein and non-protein chaperone systems, we highlight the principles that underlie chaperone action across molecular classes.

DOI: https://doi.org/10.1016/j.mam.2025.101384
bioRxiv. 2025 Jul 07. pii: 2025.07.06.663393. [Epub ahead of print]

Human TDP-43 overexpression in zebrafish motor neurons triggers MND-like phenotypes through gain-of-function mechanism.

Alison L Hogan, Madison Kane, Patrick Chiu, Grant Richter, Cindy Maurel, Sharlynn Wu, Natalie M Scherer, Emily K Don, Albert Lee, Ian Blair, Roger Chung, Marco Morsch.

Dysregulation of the TAR DNA-binding protein 43 (TDP-43), including intraneuronal cytoplasmic mislocalisation and aggregation is a feature of multiple neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), frontotemporal lobar dementia (FTLD), limbic-predominant age-related TDP-43 encephalopathy (LATE) and alzheimers disease (AD). Unravelling the causes and functional consequences of TDP-43 dysregulation is paramount to understanding disease mechanisms as well as identifying effective therapeutic targets. Here we present a comprehensive in vivo characterisation of three stable transgenic zebrafish models that express human TDP-43 variants in motor neurons. We demonstrate that overexpression of predominantly nuclear wildtype TDP-43, cytoplasm-targeted TDP-43, and an ALS-linked variant (G294V) each induce toxic gain-of-function effects, leading to impaired motor function, motor neuron loss, and muscle atrophy. Importantly, these models reveal distinct phenotypes, with the ALS-linked mutant exhibiting axonal transport deficits and neuromuscular junction disruption, while cytoplasmic mislocalised TDP-43 heightened susceptibility to oxidative stress. Two FDA-approved drugs used to treat ALS, edaravone and riluzole, were examined in these models and revealed that edaravone, but not riluzole, was effective in rescuing motor deficits associated with cytoplasmic TDP-43 expression and, to a lesser extent, mutant TDP-43 G294V . Collectively, these findings reveal distinct pathological consequences of TDP-43 dysregulation, providing neuron-centric mechanistic insights, and establish the humanised TDP-43 zebrafish as an efficient system for preclinical therapeutic testing.
Graphical abstract:

DOI: https://doi.org/10.1101/2025.07.06.663393
bioRxiv. 2025 May 10. pii: 2025.05.10.653282. [Epub ahead of print]

Scouring the human Hsp70 network uncovers diverse chaperone safeguards buffering TDP-43 toxicity.

Edward M Barbieri, Miriam Linsenmeier, Katherine R Whiteman, Yan Cheng, Sylvanne Braganza, Katie E Copley, Paola Miranda-Castrodad, Brennen Lewis, Kevin Villafañe, Defne A Amado, Beverly L Davidson, James Shorter.

Cytoplasmic aggregation and concomitant dysfunction of the prion-like, RNA-binding protein TDP-43 underpin several fatal neurodegenerative diseases, including amyotrophic lateral sclerosis. To elucidate endogenous defenses, we systematically scoured the entire human Hsp70 network for buffers of TDP-43 toxicity. We identify 30 J-domain proteins (2 DNAJAs, 10 DNAJBs, 18 DNAJCs), 6 Hsp70s, and 5 nucleotide-exchange factors that mitigate TDP-43 toxicity. Specific chaperones reduce TDP-43 aggregate burden and detoxify diverse synthetic or disease-linked TDP-43 variants. Sequence-activity mapping unveiled unexpected, modular mechanisms of chaperone-mediated protection. Typically, DNAJBs collaborate with Hsp70 to suppress TDP-43 toxicity, whereas DNAJCs act independently. In human cells, specific chaperones increase TDP-43 solubility and enhance viability under proteotoxic stress. Strikingly, spliceosome-associated DNAJC8 and DNAJC17 retain TDP-43 in the nucleus and promote liquid-phase behavior. Thus, we disambiguate a diverse chaperone arsenal embedded in the human proteostasis network that counters TDP-43 toxicity and illuminate mechanistic gateways for therapeutic intervention in TDP-43 proteinopathies.

DOI: https://doi.org/10.1101/2025.05.10.653282
Biochemistry. 2025 Jul 17.

Investigating the Stability, Flexibility, and Phase Separation Properties of H46R and H80R Disease Mutants of SOD1: Insights into ALS Pathogenesis.

Ahana Banerjee, Dwipanjan Sanyal, Krishnananda Chattopadhyay.

Human Cu, Zn superoxide dismutase (SOD1) is the primary enzyme in the cellular antioxidant defense system. Mutations in SOD1 are associated with amyotrophic lateral sclerosis (ALS), where protein misfolding and aggregation contribute to the disease pathology. Recently, SOD1 mutants have been shown to undergo phase separation, forming protein-rich droplets that can serve as precursors to the fibrillar aggregates, the pathological hallmarks of ALS. Protein phase separation is a critical process for membraneless organelle formation and the regulation of cellular activities, and its disruption is associated with neurodegeneration. In this study, we investigated two ALS-associated SOD1 mutants, H46R and H80R, and compared them to the wild-type (WT) and Apo forms to elucidate the relationship between phase separation and SOD1's biophysical properties. Using computational studies, chemical denaturation, in vitro condensate formation assays, and analyzing their dynamic behavior, we explored how these mutants influence protein phase separation propensity. Our findings demonstrate that altered secondary structures, stability, and inherent disorder in these mutants directly impact their phase separation behaviors. This study provides new insights into the role of phase separation in ALS pathogenesis and its potential as a therapeutic target.

DOI: https://doi.org/10.1021/acs.biochem.5c00289
bioRxiv. 2025 Jun 15. pii: 2025.06.13.659508. [Epub ahead of print]

DCPS modulates TDP-43 mediated neurodegeneration through P-body regulation.

Yingzhi Ye, Zhe Zhang, Yu Xiao, Chengzhang Zhu, Noelle Wright, Julie Asbury, Yongxin Huang, Weiren Wang, Laura Gomez-Isaza, Juan C Troncoso, Chuan He, Shuying Sun.

The proteinopathy of the RNA-binding protein TDP-43, characterized by nuclear clearance and cytoplasmic inclusion, is a hallmark of multiple neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Alzheimer's disease (AD). Through CRISPR interference (CRISPRi) screening in human neurons, we identified the decapping enzyme scavenger (DCPS) as a novel genetic modifier of TDP-43 loss-of-function (LOF)-mediated neurotoxicity. Our findings reveal that TDP-43 LOF leads to aberrant mRNA degradation, via disrupting the properties and function of processing bodies (P-bodies). TDP-43 interacts with P-body component proteins, potentially influencing their dynamic equilibrium and assembly into ribonucleoprotein (RNP) granules. Reducing DCPS restores P-body integrity and RNA turnover, ultimately improving neuronal survival. Overall, this study highlights a novel role of TDP-43 in RNA processing through P-body regulation and identifies DCPS as a potential therapeutic target for TDP-43 proteinopathy-related neurodegenerative diseases.

DOI: https://doi.org/10.1101/2025.06.13.659508
bioRxiv. 2025 May 05. pii: 2025.04.20.648873. [Epub ahead of print]

TDP-43 toxic gain of function links ALS, FTD and Alzheimer's Disease through splicing dysregulation.

Welmoed Van Zuiden, Thea D Meimoun, Chen Bar, Aviad Siany, Lihi Moshe, Nancy S Yacovzada, Eviatar Weizman, Manuela Neumann, Aron S Buchman, Yanling Wang, David A Bennett, Jonathan D Glass, Adam N Trautwig, Nicholas T Seyfried, Johnathan Cooper-Knock, Eran Hornstein.

Loss of nuclear TDP-43 splicing activity is a common feature across neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), but its relevance to Alzheimer's disease (AD) remains unclear. Here, we show that TDP-43 pathology in AD is broadly associated with splicing abnormalities, including aberrant splicing of amyloid precursor protein (APP). TDP-43 drives the formation of elongated APP isoforms, disrupting alternative splicing across ALS, FTLD-TDP and AD, providing a compelling mechanism for a long-standing observation of APP isoform dysregulation. We further establish a mechanistic link between TDP-43, APP splicing, and A-beta pathology. Surprisingly, the disruption to alternative APP splicing is mediated by a toxic gain of cytoplasmic TDP-43 function, rather than loss of its nuclear role. Using proximity proteomics and base editing in human iPSC-derived neurons, we show that TDP-43 pathology causes cytoplasmic co-sequestration of splicing regulators SCAF11, SRSF5, and TIAL1. Knockdown of these regulators also results in APP mis-splicing and increased A-beta burden, without affecting other TDP-43 targets such as STMN2 or UNC13A. Together, our findings suggest that TDP-43-mediated splicing dysfunction upstream of APP contributes to the pathogenesis of seemingly disparate neurodegenerative diseases, uniting AD and ALS/FTLD-TDP through a shared molecular mechanism.

DOI: https://doi.org/10.1101/2025.04.20.648873
RSC Chem Biol. 2025 Jul 10.

Random peptide mixtures of tryptophan and lysine suppress the aggregation of a cancer-related mutant of the Axin protein.

Tommaso Garfagnini, Zvi Hayouka, Assaf Friedler.

Aggregation of dysfunctional proteins can lead to a variety of diseases including cancer. We have previously developed chaperone-derived peptides that inhibit aggregation of the cancer-related L106R mutant of Axin RGS. Here we show that significantly improved inhibition was achieved using random peptide mixtures (RPMs) designed to mimic the chemical characteristics of the chaperone-like peptides. 20-mer RPMs of tryptophan and lysine suppressed aggregation of Axin RGS L106R with up to 50-fold improved activity compared to parent inhibitors. Conversely, peptides derived from the lead hotspot of Axin RGS aggregation that were designed to be specific, were unable to prevent aggregation of the protein. RPMs constitute the most efficient strategy to date to magnify peptide inhibitory activity against Axin RGS L106R aggregation, as they contain multiple active species and conformations that cover a larger inhibitory space and shield multiple hotspots at once. Our results demonstrate that the chemical composition of the peptide, and not the specific sequence, is the key factor for inhibitory activity.

DOI: https://doi.org/10.1039/d5cb00141b
Nat Chem Biol. 2025 Jul 15.

A genetically encoded selection for amyloid-β oligomer binders.

ByungUk Lee, John A Mannone, Tina Wang.

Soluble amyloid-β oligomers (AβOs) are a hypothesized source of neurotoxicity in Alzheimer disease. Binding proteins that recognize these species may have high utility in diagnostic and therapeutic applications. However, identifying binders to AβOs directly generated from the aggregation cascade is challenging because of the short lifetime and low concentrations of oligomer populations. We report a strategy to detect binding to AβOs formed during Aβ42 aggregation using a genetically encoded biosensor. We show that our method enables rapid, highly reproducible measurement of the activity of existing AβO binders and can be used to select for new binders with improved potency. We uncover hits that are >20-fold more effective than reported binders at delaying secondary nucleation, the step in Aβ aggregation thought to generate the highest number of toxic oligomers. Our approach may greatly accelerate the discovery and characterization of binding proteins that target AβOs.

DOI: https://doi.org/10.1038/s41589-025-01975-4
bioRxiv. 2025 May 01. pii: 2025.03.04.641384. [Epub ahead of print]

Pathological α-Synuclein Perturbs Nuclear Integrity.

Michael Millett, Allison Comite, Elisabeth Martin Castosa, Anika Heuberger, Preston Wagner, Ignacio Gallardo, Jessica Reinhardt, Nicole Chambers, Dominic Hall, Evan Miller, Douglas Nabert, Barbara Balsamo, Stefan Prokop, Mark Moehle.

Pathological aggregates of α-synuclein are a hallmark of a group of neurodegenerative disorders collectively termed synucleinopathies. The physiological function of α-synuclein, and the detrimental effects of the pathological variants of α-synuclein have been widely debated, but recent evidence has suggested an emerging consensus on a critical role for α-synuclein in regulating synaptic function. However, a controversial role for α-synuclein in nuclear function in both normal and pathogenic states has been proposed, and the degree to which α-synuclein localizes within the nucleus and subsequent impact on the nucleus are poorly understood. To begin to address this controversy, we employed synucleinopathy murine and cell culture models, as well as postmortem human Lewy Body Dementia tissue to elucidate the extent to which pathological α-synuclein localizes within the nuclear compartments, and the downstream consequences of this localization. We observed pathological aggregation of α-synuclein within the nucleus in both murine models and human postmortem Lewy Body Dementia cortex via quantitative super resolution microscopy. In both mouse and human brain tissue the presence of α-synuclein in the nucleus correlated with abnormal morphology of nuclei. This pathological accumulation of α-synuclein in the nucleus was not observed in control mice, human tissue without pathology, or control cells. We subsequently examined the mechanistic consequences of pathological accumulation of α-synuclein in the nucleus. Synucleinopathy models displayed increased levels of the DNA damage marker 53BP1. Furthermore, cells with pathological α-synuclein exhibited elevated markers of nuclear envelope damage and abnormal expression of nuclear envelope repair markers. Our cell culture data also suggests altered RNA localization in response to pathological α-synuclein accumulation within the nucleus. Lastly, we show that nuclear Lewy-like pathology leads to increased sensitivity to nuclear targeted toxins. Taken together, these results rigorously illustrate nuclear localization of pathological α-synuclein with super resolution methodology and provide novel insight into the ensuing impact on nuclear integrity and function.

DOI: https://doi.org/10.1101/2025.03.04.641384
bioRxiv. 2025 May 07. pii: 2025.05.07.652671. [Epub ahead of print]

Single particle dynamics of protein aggregation and disaggregation in the presence of the sHsp proteins IbpAB.

Andrew Roth, Jason Puchalla, Hays S Rye.

The small heat shock proteins (sHsps) are a key class of molecular chaperones that can inhibit protein aggregation and enhance protein recovery from aggregates. However, the mechanisms sHsps employ to carry out these roles are not well understood, in part because the highly heterogeneous and dynamic particles they form with aggregating proteins are difficult to study with traditional biophysical tools. Here we have applied a novel single particle fluorescence technique known as Burst Analysis Spectroscopy (BAS) to the study of the E. coli sHsps IbpA and IbpB (IbpAB). We show that in the presence of IbpAB, two different model proteins converge toward similar, limited aggregate particle size distributions. Additionally, while IbpAB dramatically accelerates the disassembly of protein aggregates by the bacterial KJEB bi-chaperone disaggregase, this enhancement does not appear to be strongly influenced by aggregate particle size. Rather, it is the ability of IbpAB to alter aggregate structure during particle formation that appears to be essential for stimulated disassembly. These observations support a model of aggregate recognition by IbpAB that is not only highly adaptable but capable of shaping aggregate particles into a specialized range of physical properties that are necessary for efficient protein disaggregation.

DOI: https://doi.org/10.1101/2025.05.07.652671
Molecules. 2025 Jun 24. pii: 2720. [Epub ahead of print]30(13):

Anti-Amyloid Aggregation Effects of Gobaishi (Galla chinensis) and Its Active Constituents.

Sharmin Akter, Takayuki Tohge, Sahithya Hulimane Ananda, Masahiro Kuragano, Kiyotaka Tokuraku, Koji Uwai.

  Alzheimer's disease (AD) is a chronic neurodegenerative disorder that leads to memory loss and changes in mental and behavioral functions in elderly individuals. A major pathological feature of AD is the aggregation of amyloid-beta (Aβ) peptides, along with oxidative stress, inducing neurocellular apoptosis in the brain. Gobaishi (Galla chinensis), a traditional herbal medicine, has gained considerable attention for its constituents and potent therapeutic properties, particularly its strong inhibitory activity against Aβ fibril formation. In this study, we investigated the anti-Aβ aggregation effects of Gobaishi and its active constituents. We isolated two compounds by employing Thioflavin T (ThT) assay-guided fractionation, which were identified through various spectroscopic methods as pentagalloyl glucose (PGG) and methyl gallate (MG). Evaluation of their anti-Aβ aggregation effects revealed that PGG and MG contribute 1.5% and 0.7% of the activity of Gobaishi, respectively. In addition, PGG demonstrated significantly stronger DPPH radical scavenging activity (EC50 = 1.16 µM) compared to MG (EC50 = 6.44 µM). At a concentration of 30 µM, PGG significantly reduced the Aβ-induced cytotoxicity in SH-SY5Y cell lines compared to MG. Based on these findings, both Gobaishi and its active compound PGG are proposed as promising candidates for further investigation as potent anti-amyloidogenic agents in AD management.

Keywords:  Gobaishi; amyloid-beta; antioxidant; methyl gallate; pentagalloyl glucose

DOI:  https://doi.org/10.3390/molecules30132720
Cell Rep. 2025 Jul 12. pii: S2211-1247(25)00772-7. [Epub ahead of print]44(7): 116001

TNF-α-NF-κB activation through pathological α-Synuclein disrupts the BBB and exacerbates axonopathy.

Min-Tae Jeon, Sinnead Anne Cogill, Kyu-Sung Kim, Yongjin Kim, Hyerin Kim, Chung-Yeol Lee, Suji Kim, Suhyeon Son, Jeongyeon Kim, Jaehyeok Lee, Inyeong Park, Mookyung Cheon, Do-Geun Kim.

  Dysfunction of the blood-brain barrier (BBB) is recognized as a key factor in the progression of neurodegenerative diseases (NDs), but the detailed mechanisms behind its pathogenesis and impact on neurodegeneration remain elusive. This study aimed to reveal the pathological effects of α-Synuclein (α-Syn), an aggregation protein in synucleinopathy, on BBB integrity and function and identify therapeutic targets for α-Syn-related vasculopathy. Using a brain endothelial cell model, we investigated the pathological effect of preformed fibril α-Syn (PFF) on BBB integrity, employing generative adversarial network (GAN) deep learning to analyze pathological changes. We found that PFF activates immune responses, increasing endothelial monolayer permeability via the TNF-α-NF-κB pathway. Further in vivo studies with PFF induced α-synucleinopathy, and a transgenic animal model (G2-3) revealed that α-Syn aggregation disrupts the BBB, leading to axonal degeneration that was mitigated by treatment with a non-BBB-penetrating TNF-α inhibitor, etanercept. These findings suggest that targeting brain endothelial TNF-α signaling could be a potential therapeutic approach for synucleinopathy-related NDs.

Keywords:  BBB; CP: Neuroscience; TNF-α signaling pathway; axonal degeneration; blood-brain barrier; brain endothelial cells; vasculopathy; α-synucleinopathy

DOI:  https://doi.org/10.1016/j.celrep.2025.116001
Science. 2025 Jul 17. 389(6757): eado2403

Polyglycine-mediated aggregation of FAM98B disrupts tRNA processing in GGC repeat disorders.

Jason Yang, Yunhan Xu, David R Ziehr, Martin S Taylor, Max L Valenstein, Evgeni M Frenkel, Jack R Bush, Kate Rutter, Igor Stevanovski, Charlie Y Shi, Maheswaran Kesavan, Ricardo Mouro Pinto, Ira Deveson, David P Bartel, David M Sabatini, Raghu R Chivukula.

Aggregation-prone polyglycine-containing proteins produced from expanded GGC repeats are implicated in an emerging family of neurodegenerative disorders. In this study, we showed that polyglycine itself forms aggregates that incorporate endogenous glycine-rich proteins, including FAM98B, a component of the transfer RNA (tRNA) ligase complex (tRNA-LC) that harbors the most glycine-rich sequence in the human proteome. Through this glycine-rich intrinsically disordered region (IDR), polyglycine sequesters and depletes the tRNA-LC, disrupting tRNA processing. Accordingly, patient tissues revealed aggregate-associated FAM98B depletion and accumulation of aberrant tRNA splicing intermediates. Furthermore, Fam98b depletion in adult mice caused progressive motor coordination deficits and hindbrain pathology. Our data suggest that the FAM98B glycine-rich IDR mechanistically links previously disparate neurodegenerative disorders of protein aggregation and tRNA processing.

DOI: https://doi.org/10.1126/science.ado2403
bioRxiv. 2025 Jun 25. pii: 2025.06.23.661052. [Epub ahead of print]

Tau Clearance Reverses Neuronal Dysfunction in Both Young and Aged C. elegans.

T Carroll, G V W Johnson, K Nehrke.

Alzheimer's Disease (AD) is an age-related dementia and presents a growing medical and economic burden as the average human lifespan continues to rise. AD is classically diagnosed via the accumulation and aggregation of two major proteins: amyloid-β and tau. To date, potential and FDA-approved therapies designed to clear these aggregates at best delay rather than prevent disease, indicating that the root cause of AD lay upstream of aggregate formation. Tau protein's phosphorylation is critical for AD progression, and phosphorylation at Threonine 231 is thought to be an early disease-associated, "gatekeeper" event. Previously, we showed that genomic, single-copy insertion of phosphomimetic human tau (T231E) into C. elegans mechanosensory neurons induced age-dependent deficits in light-touch sensation. Herein, we have generated new C. elegans models which express pan-neuronal human tau to assess the idea of selective vulnerability and whether specific neuronal behaviors might be impacted preferentially. We also tested whether tau clearance via an Auxin Inducible Degron (AID) could reverse these deficits. Despite our hypothesis that prolonged stress in older animals would induce irreversible metabolic rewiring or maladaptation, tau depletion rescued known behavioral deficits at all ages tested, including in old worms which displayed the most overt phenotypes. Taken together, our data suggest that neuronal dysfunction induced by phosphorylated tau is reversible and provides reassurance that current early-phase therapeutic efforts aimed at reducing soluble tau levels in AD patients may prove effective.

DOI: https://doi.org/10.1101/2025.06.23.661052
Biochem Biophys Rep. 2025 Sep;43 102118

Microtubule-associated protein 4 forms aggregates consisting of helical filaments.

Shuto Miura, Eisuke Ishibashi, Takuto Nakamichi, Koji Uwai, Masahiro Kuragano, Kiyotaka Tokuraku.

  We previously reported that microtubule-associated protein (MAP) 4 was detected in the cytoplasm as abnormal "puncta" in post-ischemic mouse cardiomyocytes. MAP4, a member of the MAP superfamily, has a repeat region consisting of multiple microtubule-binding sequences in its microtubule-binding domain (MBD), like tau. The tau forms aggregates composed of amyloid fibrils and grows into neurofibrillary tangles in neurons. Therefore, we hypothesized that MAP4 also forms amyloid fibrils in cells. Here, we observed whether MAP4 forms aggregates composed of amyloid fibrils using fluorescence microscopy and transmission electron microscopy with quantum dot (QD) nanoprobes. Since we had previously succeeded in real-time 3D imaging of tau MBD fragment aggregate formation using QD nanoprobes, we attempted to observe aggregates using human MAP4 MBD fragments under the same conditions. Fluorescence microscopy showed that 10 μM MAP4 formed aggregates at a rate similar to that of tau. Time-laps 3D imaging by confocal laser microscopy revealed that MAP4 aggregate grains were smaller in size and the deposits were thinner than tau aggregates. Transmission electron microscopy of the MAP4 aggregates revealed that they consisted of helical filaments with a width of 22.6 ± 2.8 nm and a helical pitch length of 48.2 ± 8.4 nm. The helical filaments of MAP4 were shorter in width and longer in helical pitch than those of tau. Furthermore, MAP4 aggregates did not increase the fluorescence intensity of thioflavin T (ThT), and the circular dichroism (CD) spectrum slightly differed from that of tau. These findings suggest that while MAP4 forms aggregates composed of helical filaments similar to those of tau, the structural properties of these filaments are somewhat distinct.

Keywords:  Amyloid fibril; Microtubule-associated protein 4; Myocardial infarction; Protein aggregation; Quantum dot; Tau

DOI:  https://doi.org/10.1016/j.bbrep.2025.102118
Int J Mol Sci. 2025 Jul 01. pii: 6351. [Epub ahead of print]26(13):

The Emerging Role of the Molecular Chaperone Clusterin in Parkinson's Disease.

Giulia Carini, Salihu Mohammed, Alice Filippini, Ileana Ramazzina, Isabella Russo.

  Clusterin (CLU) is a heterodimeric, ATP-independent molecular chaperone that exhibits high expression in the brain. While CLU primarily functions in the extracellular environment, its chaperone activity in the intracellular compartment under different stress conditions, as well as its involvement in various signaling networks, has been demonstrated. CLU has been extensively associated with Alzheimer's Disease; however, increasing evidence links this chaperone to Parkinson's Disease (PD) as well. Thus, in this review we will discuss evidence concerning the involvement of CLU in the pathogenesis of PD with a particular focus on molecular mechanisms leading to the formation and the spreading of alpha-Synuclein (α-Syn) aggregates. Specifically, the role of CLU will be discussed in neurons and in glial cells, taking into account that the neuron-glia cross-talk is an essential and dynamic interplay that is compromised in neurodegenerative disorders. Moreover, the possible role of CLU as a biomarker in different biological fluids, such as cerebrospinal fluid, plasma, and serum, and its therapeutic potential will be addressed. In this regard, the past years have seen huge efforts to discover molecules able to mitigate α-Syn burden and its related toxicity. Overall, this overview highlights CLU as an intriguing target that can affect biochemical events underlying PD pathology.

Keywords:  Clusterin; Parkinson’s disease; astrocytes; neurons; α-Synuclein

DOI:  https://doi.org/10.3390/ijms26136351
bioRxiv. 2025 Jul 13. pii: 2025.07.10.664197. [Epub ahead of print]

Impact of sex and glial tau expression on heat shock protein induction in a Drosophila model of tauopathy.

Margot Whitmore, Maeve Coughlan, Martha A Kahlson, Jaasiel Alvarez, Louisa Zebrowski, Kenneth J Colodner, Kathryn A McMenimen.

Heat shock proteins (Hsps) are central components of the cellular stress response and serve as the first line of defense against protein misfolding and aggregation. Disruption of this proteostasis network is a hallmark of neurodegenerative diseases, including tauopathies - a class of neurodegenerative diseases characterized by intracellular tau accumulation in neuronal and glial cells. Although specific Hsps are enriched in glial cells, and some have been shown to directly bind tau and influence its aggregation, the broader interplay between Hsps and tau remains poorly understood. In particular, it is unclear whether tau expression affects the heat shock response, and whether this interaction is modulated in a sex-specific fashion. Here, we used a Drosophila model of tauopathy to examine both inducible and constitutive Hsp expression in response to heat stress in the context of glial tau expression. We found that Hsp expression displays sexually dimorphic expression patterns at basal levels and in response to heat stress. Moreover, tau expression in glia disrupts the normal induction of specific heat shock proteins following heat stress. This work provides new insight into how tau interacts with the cellular stress response, and highlights sex-specific differences in Hsp regulation. Understanding these molecular connections is crucial to understanding how the presence of tau in glial cells influences the stress response, and potentially contributes to tauopathy pathogenesis.

DOI: https://doi.org/10.1101/2025.07.10.664197
bioRxiv. 2025 Jun 09. pii: 2025.06.06.658328. [Epub ahead of print]

Accumulation of LRRK2-associated phospho-Rab12 degenerative lysosomes in tauopathies.

Silas A Buck, Tuyana Malankhanova, Eileen B Ma, Sarah Yim, Harrison W Pratt, John Ervin, Shih-Hsiu J Wang, Todd J Cohen, Andrew B West, Laurie H Sanders.

Parkinson's disease (PD) pathogenic mutations in leucine-rich repeat kinase 2 ( LRRK2 ) are associated with endolysosomal dysfunction across cell types, and carriers of LRRK2 mutations variably present with phosphorylated tau and α-synuclein deposits in post-mortem analysis. LRRK2 mutations increase the phosphorylation of Rab substrates including Rab12. Rab12 is expressed in neuronal and non-neuronal cells with localization to membranes in the endolysosomal compartment. Under lysosomal stress, LRRK2 interaction with Rab12 upregulates LRRK2 kinase activity. In this study, using a recently developed monoclonal antibody directed to the LRRK2-mediated phosphorylation site on Rab12 at amino acid Ser106 (pS106-Rab12), we test whether aberrant LRRK2 phosphorylation is associated with tau and/or α-synuclein pathology across clinically distinct neurodegenerative diseases. Analysis of brain tissue lysates and immunohistochemistry of pathology-susceptible brain regions demonstrate that pS106-Rab12 levels are increased in Dementia with Lewy bodies (DLB), Alzheimer's disease (AD), and PD, and in LRRK2 mutation carriers. In early pathological stages, phosphorylated Rab12 localizes to granulovacuolar degeneration bodies (GVBs), which are thought to be active lysosomal-like structures, in neurons. pS106-Rab12-positive GVBs accumulate with pathological tau across brain tissues in DLB, AD, and PD, and in LRRK2 mutation carriers. In a mouse model of tauopathy, pS106-Rab12 localizes to GVBs during early tau deposition in an age-dependent manner. While GVBs are largely absent in neurons with mature protein pathology, subsets of both tau and α-synuclein inclusions appear to incorporate pS106-Rab12 at later pathological stages. Finally, pS106-Rab12 labels GVBs in neurons and shows widespread co-pathology with tau inclusions in primary tauopathies including Pick's disease, progressive supranuclear palsy and corticobasal degeneration. These results implicate LRRK2 kinase activity and Rab phosphorylation in endolysosomal dysfunction in both tau and α-synuclein-associated neurodegenerative diseases.

DOI: https://doi.org/10.1101/2025.06.06.658328
Res Sq. 2025 Jul 10. pii: rs.3.rs-6978813. [Epub ahead of print]

Lysosomal Protease-Mediated APP Degradation is pH-Dependent, Mutation-Sensitive, and Facilitates Tau Proteolysis.

Caroline Ackley, Zoe Liau, Shruti Arya, Tara Antee, Giselle M Knudsen, Courtney Lane-Donovan, Paul J Sampognaro, Aimee W Kao.

Background: The accumulation and aggregation of amyloid beta (A$\beta$)---a peptide fragment derived from the proteolytic processing of amyloid precursor protein (APP)---is a central pathological feature of Alzheimer's disease (AD) and a current target for disease-modifying therapies. Mutations in APP can also drive early-onset AD. While the roles of $\alpha$-, $\beta$-, and $\gamma$-secretases and their respective cleavage sites in APP processing are well characterized, much less is understood about the routine degradation of APP within sub-cellular compartments like the lysosome. Methods: We applied Multiplexed Substrate Profiling by Mass Spectrometry (MSP-MS) to map cleavage sites within APP that may be targeted by lysosomal proteases, also known as cathepsins. We then employed cell-based and in vitro assays to examine the degradation of both wild-type and mutant APP by these enzymes. Results: Our findings confirm that APP is enriched in the endo-lysosomal compartment, where it is processed by many, but not all, cathepsins. Our experiments reveal that cleavages at several mapped APP sites are sensitive to both changes in pH and the presence of pathogenic variants E693G and E693Q. Additionally, we discovered that the large soluble domain of APP (sAPP) enhances tau cleavage by cathepsin G in vitro. Conclusions: Collectively, these results underscore the importance of lysosomal processing of APP, identify a link between APP and tau, and suggest new avenues for exploring AD pathogenesis. They also point to potential therapeutic targets related to the lysosomal function of APP and its impact on neurodegenerative disease.

DOI: https://doi.org/10.21203/rs.3.rs-6978813/v1