bims-proned 2025-10-19 papers

bims-proned

Biomed News

on Proteostasis in neurodegeneration

Issue of 2025–10–19
twenty papers selected by
Verena Kohler, Umeå University

Ubiquilin-2 liquid droplets catalyze α-synuclein fibril formation.
Photoactivatable Ru(ii) polypyridyl complexes as dual action modulators of amyloid-beta peptide aggregation and Cu redox cycling.
Self-consistent analytical solutions to the kinetics of lipid-induced protein aggregation.
The role of small GTPases in Alzheimer's disease tau pathologies.
Protein Recognition of Linear and Cyclic Peptides of Homologous Sequences Implicated in the Aggregation of α-Synuclein.
Molecular Pathways and Recent Therapeutic Strategies for Polyglutamine Diseases.
Spectral Profiling of Early αsyn Aggregation in HEK293 Cells Modified to Stably Express Human WT and A53T-αsyn.
Nano-conjugation of small molecule modulators of protein aggregation: Enhancing the therapeutic precision.
Rapamycin and Autophagy: Potential Therapeutic Approach for Parkinson's Disease Treatment.
Multiscale Simulations Elucidate the Mechanism of Polyglutamine Aggregation and the Role of Flanking Domains in Fibril Polymorphism.
Lactobacilli Probiotics Prevent Amyloid-Beta Fibril Formation In Vitro.
Lon/Pim1 mediated degradation of presequence translocase-associated motor components Pam16 and Pam18 in Saccharomyces cerevisiae.
Impact of Sex and Glial Tau Expression on Heat Shock Protein Induction in a Drosophila Model of Tauopathy.
Multi-Fused S,N-Heterocyclic Compounds for Targeting α-Synuclein Aggregates.
Effect of temperature on the aggregation of an Fc-fusion protein under agitation.
Direct interaction between TDP-43 and Tau promotes their co-condensation, while suppressing Tau fibril formation and seeding.
Multicomponent Synthesis of Multi-Target Quinazolines Modulating Cholinesterase, Oxidative Stress, and Amyloid Aggregation Activities for the Therapy of Alzheimer's Disease.
Kinetic Mechanism of Heparin-Induced Fibrillation of α-Synuclein.
Optofluidic Waveguides for the Label-Free Study of Silk Protein Aggregates.
Temporal Interactome Mapping of Human Tau in Drosophila Reveals Progressive Mitochondrial Engagement and Porin/VDAC1-Dependent Modulation of Toxicity.

EMBO J. 2025 Oct 14.

Ubiquilin-2 liquid droplets catalyze α-synuclein fibril formation.

Tomoki Takei, Yukiko Sasazawa, Daisuke Noshiro, Mitsuhiro Kitagawa, Tetsushi Kataura, Hiroko Hirawake-Mogi, Emi Kawauchi, Yuya Nakano, Etsu Tashiro, Tsuyoshi Saitoh, Shigeru Nishiyama, Seiichiro Ogawa, Soichiro Kakuta, Saiko Kazuno, Yoshiki Miura, Daisuke Taniguchi, Viktor I Korolchuk, Nobuo N Noda, Shinji Saiki, Masaya Imoto, Nobutaka Hattori.

  Liquid-liquid phase separation (LLPS) and subsequent liquid-gel/solid transition are considered common aggregation mechanisms of proteins linked to neurodegenerative diseases. α-synuclein (α-syn), the main factor in Parkinson's disease pathology, has been reported to undergo LLPS, thereby accelerating aggregate formation. However, the precise molecular events involved in the early stages of α-syn aggregation remain controversial. In this study, we show that α-syn aggregation is promoted by droplets formed by ubiquilin-2 (UBQLN2), rather than by α-syn LLPS itself. During the liquid-gel/solid transition of UBQLN2 droplets, α-syn within the droplets transforms into pathogenic fibrils both in vitro and in cells. Immunohistochemistry of brain sections from sporadic Parkinson's disease patients revealed UBQLN2 in substantia nigra Lewy bodies, implicating UBQLN2 in α-syn aggregation in vivo. Furthermore, the small compound SO286 inhibited both UBQLN2 self-association and its interaction with α-syn by binding to the STI1 domain, thereby suppressing α-syn aggregation. These findings demonstrate that UBQLN2 droplets catalyze α-syn fibrillization and suggest that small molecules targeting fibril-catalyzing proteins such as UBQLN2 may represent a promising therapeutic approach for neurodegenerative diseases.

Keywords:  Liquid–liquid Phase Separation; Parkinson’s Disease; Ubiquilin-2; α-synuclein

DOI:  https://doi.org/10.1038/s44318-025-00591-1
Chem Sci. 2025 Oct 01.

Photoactivatable Ru(ii) polypyridyl complexes as dual action modulators of amyloid-beta peptide aggregation and Cu redox cycling.

Grace Leech, Alfredo Lopez Acosta, Samyadeb Mahato, Patrick C Barrett, Rachel O Hodges, Sherri A McFarland, Tim Storr.

The misfolding and aggregation of the amyloid-β (Aβ) peptide is a major hallmark of Alzheimer's disease (AD), yet therapeutic strategies targeting this process have faced long-standing challenges related to efficacy and specificity. Here, we investigate two photoactivatable Ru(ii) polypyridyl complexes (RuP) that operate as dual-action modulators of AD pathology by addressing both Aβ aggregation and Cu-Aβ associated ROS generation. The RuP contain an extended planar imidazo[4,5-f] [1,10]phenanthroline ligand, which is important for pre-association with the Aβ peptide via hydrophobic and π-π interactions, as well as sterically hindered ligands 6,6'-dimethyl-2,2'-bipyridyl (6,6'-dmb) for RuP1 and 2,9-dimethyl-1,10-phenanthroline (2,9-dmp) for RuP2, which cause steric strain at the metal center. Photoactivation of the RuP results in loss of either a 6,6'-dmb or 2,9-dmp ligand exposing cis-exchangeable coordination sites for binding to the Aβ peptide, which immediately redirects the Aβ peptide away from its β-sheet-rich fibrillization pathway, promoting the formation of amorphous, off-pathway aggregates that exhibit increased sensitivity to proteolytic degradation. We find that the photoactivated RuP are closely associated with the amorphous aggregates, and that this is a common endpoint regardless of Aβ peptide aggregation state (monomer, oligomer, or fibril). Importantly, we show that the ejected ligands also inhibit the redox cycling and ROS generation of Cu-Aβ species. Together, these results highlight the potential of photoactivatable RuP as multifunctional therapeutic candidates, offering a rational approach to intercepting Aβ aggregation and Cu-mediated oxidative stress, and advancing the design of light-responsive treatments for neurodegenerative diseases.

DOI: https://doi.org/10.1039/d5sc05593h
J Chem Phys. 2025 Oct 14. pii: 144905. [Epub ahead of print]163(14):

Self-consistent analytical solutions to the kinetics of lipid-induced protein aggregation.

Alisdair Stevenson, David Voderholzer, Thomas C T Michaels.

The aggregation of proteins into amyloid fibrils is a hallmark of several neurodegenerative disorders, including Parkinson's disease. A growing body of experimental evidence highlights the significant role lipid membranes play in modulating this aggregation process, particularly for proteins such as α-synuclein. Despite this, there has been a lack of quantitative theoretical frameworks capable of describing the kinetics of lipid-induced protein aggregation. In this work, we develop an analytical theoretical model that explicitly incorporates lipid-mediated interactions into the aggregation kinetics. By formulating rate equations in terms of lipid surface coverage and applying a fixed-point analysis, we derive self-consistent solutions for the full timecourse of aggregation. Our model captures both one-step and two-step nucleation mechanisms and enables the prediction of key kinetic observables, including half-times and maximal growth rates. These results provide a quantitative foundation for interpreting experimental data and offer new mechanistic insights into how lipids influence the self-assembly of amyloidogenic proteins.

DOI: https://doi.org/10.1063/5.0279601
Front Cell Neurosci. 2025 ;19 1650400

The role of small GTPases in Alzheimer's disease tau pathologies.

Peter Hoegy, Yan-Hua Chen, Qun Lu.

  Microtubule-associated protein (MAP) tau stabilizes neuronal microtubules in axonal transport and contributes to healthy synapses. In Alzheimer's disease (AD), tau proteins become hyperphosphorylated, reduce microtubule binding, and aggregate into paired helical filaments (PHFs) in neurofibrillary tangles (NFTs). Although the steps of this dysregulation of tau are well established, the mechanisms by which each step is regulated remain incompletely understood. Misfolded protein aggregates, such as amyloid β-peptides (Aβ), are degraded by autophagy and lysosomal pathways, in which small GTPases play essential roles. However, how tau aggregates and spreads from nerve cells and whether small GTPases similarly play pivotal roles are not as clear. Here we review the recent evidence to propose that small GTPases are important in tau protein posttranslational phosphorylation, aggregation, and clearance. As such, small GTPases may prove to be important therapeutic targets that can reduce the AD tau burden.

Keywords:  Alzheimer’s disease; aggregation; clearance; hyperphosphorylation; microtubule-associated protein tau; neurofibrillary tangles; propagation; small GTPases

DOI:  https://doi.org/10.3389/fncel.2025.1650400
J Phys Chem B. 2025 Oct 13.

Protein Recognition of Linear and Cyclic Peptides of Homologous Sequences Implicated in the Aggregation of α-Synuclein.

Gabriel F Martins, Cristiano Rocha, Nuno Galamba.

Various amino acid sequences have been suggested to play key roles in the aggregation of α-synuclein (α-syn), implicated in Parkinson's disease and other synucleinopathies. A drug development strategy is, therefore, the design of molecules that bind to these sequences in the monomer. The latter, either alone or coupled with antiaggregation groups, could preclude homogeneous and/or heterogeneous primary nucleation by either blocking protein-protein interactions or stabilizing the monomer in its solution and/or membrane-bound conformations, respectively. Here, using molecular dynamics simulations, we assessed the specificity of in trans linear peptides (P1, NACore, and NACterm) and their cyclic counterparts toward homologous sequences in the N-terminal and NAC domains of α-syn, which have been experimentally shown to play key roles in aggregation. The results suggest that, despite some differences, both linear and cyclic peptides display specificity toward their homologous sequences in α-syn. Hence, these peptides have the potential to serve as recognition elements coupled with amyloid aggregation modulators or inhibitors. Additionally, most peptides stabilize the α-helices in the NAC region of α-syn when in a membrane-bond-like conformation and some induce more extended conformations when in a disordered form. However, our results also show that some peptides might eliminate intramolecular interactions with potential protective roles against aggregation. The results are further compared with the monomer at high temperatures, at which the protein adopts a more compact structure, and exhibits increased intramolecular β-sheet content, associated with an increase of the hydrophobic effect.

DOI: https://doi.org/10.1021/acs.jpcb.5c05501
Curr Mol Med. 2025 Oct 08.

Molecular Pathways and Recent Therapeutic Strategies for Polyglutamine Diseases.

Sagor Kumar Roy, Ashima Barman, Seidu A Richard, Bijal Arvinkumar Lacmane.

  The abnormal expansion of trinucleotide cytosine-adenine-guanine [CAG] repeats within disease-associated genes is the primary cause of polyglutamine [polyQ] diseases. This study aims to evaluate the pathological threshold at which the polyglutamine [polyQ] tract, following mutation, leads to neurotoxic effects and to explore emerging therapeutic strategies targeting these mechanisms. The formation of protein aggregates comprising pathogenic polyQ proteins, which induce cellular cytotoxicity, is a key hallmark of polyQ diseases. Despite extensive research, the molecular pathways responsible for the cellular toxicity caused by mutant polyQ proteins remain untreatable. However, strategies to reduce the abnormal expansion of CAG repeats, inhibit the accumulation and aggregation of toxic polyQ-expanded proteins, and promote protein refolding, degradation, or prevention of proteolytic cleavage have shown promise. Additionally, therapeutic approaches such as induced autophagy and stem cell therapies represent promising avenues for intervention. Current treatment modalities for polyQ diseases primarily focus on temporarily alleviating symptoms and slowing disease progression. Continued research into targeted therapeutic strategies is essential to address the underlying pathophysiology of these disorders effectively.

Keywords:  CAG; Polyglutamine disease; autophagy; protein aggregation; stem cell therapy.; therapeutic strategies

DOI:  https://doi.org/10.2174/0115665240393446250829084646
Cells. 2025 Oct 02. pii: 1542. [Epub ahead of print]14(19):

Spectral Profiling of Early αsyn Aggregation in HEK293 Cells Modified to Stably Express Human WT and A53T-αsyn.

Priyanka Swaminathan, Karsten Sættem Godø, Eline Bærøe Bjørn, Therése Klingstedt, Debdeep Chatterjee, Per Hammarström, Rajeevkumar Raveendran Nair, Mikael Lindgren.

  Alpha-synuclein (αsyn) misfolding and aggregation underlie several neurodegenerative disorders, including Parkinson's disease. Early oligomeric intermediates are particularly toxic yet remain challenging to detect and characterize within cellular systems. Here, we employed the luminescent conjugated oligothiophene h-FTAA to investigate early aggregation events of human wildtype (huWT) and A53T-mutated αsyn (huA53T) both in vitro and in HEK293 cells stably expressing native human-αsyn. Comparative fibrillation assays revealed that h-FTAA detected αsyn aggregation with higher sensitivity and earlier onset than Thioflavin T, with the A53T variant displaying accelerated fibrillation. HEK293 cells stably expressing huWT- or huA53T-αsyn were exposed to respective pre-formed fibrils (PFFs), assessed via immunocytochemistry, h-FTAA staining, spectral emission profiling, and fluorescence lifetime imaging microscopy (FLIM). Notably, huA53T PFFs promoted earlier aggregation patterns and yielded narrower fluorescence lifetime distributions compared with huWT PFFs. Spectral imaging showed h-FTAA emission maxima (~550-580 nm) red-shifted and broadened in cells along with variable lifetimes (0.68-0.87 ns), indicating heterogeneous aggregate conformations influenced by cellular milieu. These findings demonstrate that h-FTAA is useful for distinguishing early αsyn conformers in living systems and, together with stable αsyn-expressing HEK293 cells, offers a platform for probing early αsyn morphotypes. Taken together, this opens for further discovery of biomarkers and drugs that can interfere with αsyn aggregation.

Keywords:  A53T mutation; HEK293 cells; Parkinson’s disease; ThT; alpha-synuclein; fibrillation kinetics assay; fluorescence lifetime imaging; h-FTAA; pre-formed fibrils; spectral imaging; stable αsyn

DOI:  https://doi.org/10.3390/cells14191542
Int J Biol Macromol. 2025 Oct 13. pii: S0141-8130(25)08850-6. [Epub ahead of print] 148293

Nano-conjugation of small molecule modulators of protein aggregation: Enhancing the therapeutic precision.

Syed Ifrah Manzoor, Ishfaq Ahmad Ahanger, Majid Rasool Kamli, Maqsood Ahmad Malik, Tanveer Ali Dar.

  Protein aggregation is a central hallmark of several neurodegenerative and systemic diseases, including Alzheimer's, Parkinson's, cataract and type 2 diabetes. Consequently, targeting protein aggregation is emerging as a promising therapeutic strategy for these diseases. Small molecule modulators have exhibited considerable potential in stabilizing native protein conformations and promoting the dissolution of toxic aggregates, leading to delayed disease progression. Some also target proteostatic pathways, promoting clearance of misfolded proteins to prevent further aggregation. Despite being promising, their clinical efficacy often faces challenges due to poor bioavailability, limited stability, and lack of specificity. Recent advances in nanotechnology have introduced nano-conjugation as a potential strategy for maximizing the therapeutic efficacy of these small molecule modulators. By ensuring targeted delivery, increased availability, improved stability and controlled tissue release, nano-conjugation has not only overcome the limitations but also acts as a future pathway to precision medicine in protein aggregation diseases. The present review article provides a comprehensive overview of small molecule modulators of protein aggregation and explores how nano-conjugation enhances their therapeutic efficacy. Moreover, it highlights emerging clinical trials and explores future directions in the application of nano-conjugated small molecule modulators as a potential treatment strategy for protein aggregation diseases.

Keywords:  Drug delivery; Nanomedicine; Osmolyte; Phytochemicals; Protein misfolding; Protein stability

DOI:  https://doi.org/10.1016/j.ijbiomac.2025.148293
CNS Neurol Disord Drug Targets. 2025 Oct 14.

Rapamycin and Autophagy: Potential Therapeutic Approach for Parkinson's Disease Treatment.

Ahsas Goyal, Anshika Kumari, Aanchal Verma, Neetu Agrawal.

  Parkinson's disease (PD) is a chronic, progressive neurodegenerative disorder marked by the degeneration of dopaminergic neurons in the substantia nigra, leading to characteristic motor symptoms such as bradykinesia, tremor, and rigidity, as well as a range of non-motor manifestations including cognitive impairment, mood disturbances and autonomic dysfunction. Among the multiple cellular mechanisms implicated in PD, the dysregulation of autophagy has gained significant attention in recent years. Autophagy is a crucial intracellular degradation pathway responsible for the removal of misfolded proteins and damaged organelles, processes that are particularly relevant in neurodegenerative diseases. Impairment of autophagic flux contributes to the accumulation of toxic protein aggregates and cellular stress in PD. Rapamycin, a compound originally isolated from Streptomyces hygroscopicus, is a well-established inhibitor of the mechanistic target of rapamycin (mTOR), a central regulator of autophagy. Preclinical studies have shown that rapamycin can stimulate autophagic pathways by suppressing mTOR signalling, leading to increased expression of autophagy markers. These effects have been associated with reduced neuronal damage, improved motor performance and decreased accumulation of pathological proteins in PD models. This review provides an overview of current preclinical research on rapamycin's neuroprotective potential in PD through autophagy enhancement. Although findings are promising, translating these outcomes into clinical practice necessitates a thorough understanding of rapamycin's pharmacodynamics, optimal dosing strategies, potential side effects and long-term safety. Further research is essential to establish its therapeutic viability in human populations.

Keywords:  Rapamycin; autophagy; mTOR and Parkinson's disease.; neuroprotection

DOI:  https://doi.org/10.2174/0118715273401017250918141227
J Phys Chem B. 2025 Oct 15.

Multiscale Simulations Elucidate the Mechanism of Polyglutamine Aggregation and the Role of Flanking Domains in Fibril Polymorphism.

Avijeet Kulshrestha, Tien Minh Phan, Azamat Rizuan, Priyesh Mohanty, Jeetain Mittal.

Protein aggregation, which is implicated in aging and neurodegenerative diseases, typically involves a transition from soluble monomers and oligomers to insoluble fibrils. Polyglutamine (polyQ) tracts in proteins can form amyloid fibrils, which are linked to polyQ diseases, including Huntington's disease (HD), where the length of the polyQ tract inversely correlates with the age of onset. Despite significant research on the mechanisms of Httex1 aggregation, atomistic information regarding the intermediate stages of its fibrillation and the morphological characteristics of the end-state amyloid fibrils remains limited. Recently, molecular dynamics (MD) simulations based on a hybrid multistate structure-based model, Multi-eGO, have shown promise in capturing the kinetics and mechanism of amyloid fibrillation with high computational efficiency while achieving qualitative agreement with experiments. Here, we utilize the Multi-eGO simulation methodology to study the mechanism and kinetics of polyQ fibrillation and the effect of the N17 flanking domain of the huntingtin protein. Aggregation simulations of polyQ produced highly heterogeneous amyloid fibrils with variable-width branched morphologies by incorporating combinations of β-turn, β-arc, and β-strand structures, while the presence of the N17 flanking domain reduced amyloid fibril heterogeneity by favoring β-strand conformations. Our simulations reveal that the presence of the N17 domain enhanced aggregation kinetics by promoting the formation of large, structurally stable oligomers. Furthermore, the early-stage aggregation process involves two distinct mechanisms: backbone interactions driving β-sheet formation and side-chain interdigitation. Overall, our study provides detailed insights into the fibrillation kinetics, mechanisms, and end-state polymorphism associated with Httex1 amyloid aggregation.

DOI: https://doi.org/10.1021/acs.jpcb.5c06627
Probiotics Antimicrob Proteins. 2025 Oct 13.

Lactobacilli Probiotics Prevent Amyloid-Beta Fibril Formation In Vitro.

Sanaa Harrass, Michael Quansah, Sachin Kumar, Michael Radzieta, Bhawantha Jayawardena, Christopher Jones, Monique David, Benjamin Heng, Liam D H Elbourne, Seth Amanquah, Patrick Adjei, Mario Capunzo, Silvana Mirella Aliberti, Slade O Jensen, Mourad Tayebi.

  Alzheimer's disease (AD) is characterized by the buildup of extracellular aggregated amyloid-β (Aβ) peptides, following sequential enzymatic cleavage of amyloid precursor protein, along with intraneuronal accumulation of hyperphosphorylated Tau proteins and subsequent neuronal loss. Despite extensive research, the precise mechanisms underlying Aβ and Tau-mediated neurodegeneration remain elusive. Inhibiting protein aggregation has been a primary focus for mitigating neuronal toxicity. Probiotics have emerged as a promising preventative measure against cognitive decline in AD, with several in vivo and clinical trials demonstrating the efficacy of select bacterial strains in slowing AD progression. However, these studies lack direct molecular evidence on the effects of probiotics on Aβ aggregation kinetic. Inhibiting protein aggregation is key to reducing neuronal toxicity. While probiotics have shown promise in preventing cognitive decline in Alzheimer's disease, supported by in vivo and clinical studies, direct molecular evidence of their impact on Aβ aggregation kinetics remains lacking. In this study, we conducted bioinformatic and physicochemical assessments, including molecular docking of proteins derived from 13 probiotic strains against Aβ and Tau, identifying four strains predicted to efficiently inhibit Aβ aggregation. Kinetic studies confirmed that both the probiotic formulation and its derived supernatant significantly inhibited the conversion of monomeric Aβ and Tau into aggregated forms. To explore bioavailability, we administered the probiotic formulation to healthy individuals and detected its presence in stool samples, demonstrating survival through the gastrointestinal tract. These findings suggest that specific probiotic strains may serve as therapeutic candidates for targeting Aβ and/or Tau aggregation, with further studies warranted to assess their potential clinical utility in AD.

Keywords:  Alzheimer’s disease; Amyloid β; Lactobacilli probiotics; Microbiome; Molecular docking; Protein aggregation; Tau protein

DOI:  https://doi.org/10.1007/s12602-025-10776-z
Biochem J. 2025 Oct 10. pii: BCJ20243016. [Epub ahead of print]

Lon/Pim1 mediated degradation of presequence translocase-associated motor components Pam16 and Pam18 in Saccharomyces cerevisiae.

Yerranna Boggula, Arpan Chatterjee, Gaurav Simaiya, Amita Pal, Akash Srinivasan, Naresh Babu Sepuri.

  Mitochondrial protein homeostasis depends mainly on the efficient import and folding of nuclear-encoded proteins, and defects in this process can lead to proteotoxicity, which is harmful to the cell. Mitochondrial chaperones and proteases are essential defense mechanisms that ensure dysfunctional proteins' proper concentration, folding, and degradation. Lon protease 1 (Pim1 in yeast) is the mitochondrial matrix protease known to prevent protein aggregation by degrading unfolded proteins. Here, we show that two essential components of ATP-dependent presequence translocase and associated motor (PAM complex)- Pam18 and Pam16 are specifically targeted for degradation by the proteolytically active Lon/Pim1, both in vitro and in vivo. Further, overexpression of Pam18 and Pam16 exacerbates the growth defect of the delta pim1 strain. Hence, our study reveals, for the first time, that components involved in protein import are substrates of Pim1, which could have potential implications for regulating mitochondrial protein import and proteostasis.

Keywords:  Lon/Pim1 protease; Mitochondria; Protein turnover; Proteolysis; Proteostasis; Saccharomyces cerevisiae; mitochondrial protein import; presequence translocase-associated motor

DOI:  https://doi.org/10.1042/BCJ20243016
ACS Omega. 2025 Oct 07. 10(39): 45921-45932

Impact of Sex and Glial Tau Expression on Heat Shock Protein Induction in a Drosophila Model of Tauopathy.

Marguerite 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/10.1021/acsomega.5c06686
Cells. 2025 Sep 30. pii: 1531. [Epub ahead of print]14(19):

Multi-Fused S,N-Heterocyclic Compounds for Targeting α-Synuclein Aggregates.

Chao Zheng, Jeffrey S Stehouwer, Goverdhan Reddy Ummenthala, Yogeshkumar S Munot, Neil Vasdev.

  The development of positron emission tomography (PET) tracers targeting α-synuclein (α-syn) aggregates is critical for the early diagnosis, differential classification, and therapeutic monitoring of synucleinopathies such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy. Despite recent advances, challenges including the low abundance of α-syn aggregates (10-50× lower than amyloid-beta (Aβ) or Tau), structural heterogeneity (e.g., flat fibrils in PD vs. cylindrical forms in DLB), co-pathology with Aβ/Tau, and poor metabolic stability have hindered PET tracer development for this target. To optimize our previously reported pyridothiophene-based radiotracer, [18F]asyn-44, we present the synthesis and evaluation of novel S,N-heterocyclic scaffold derivatives for α-syn. A library of 49 compounds was synthesized, with 8 potent derivatives (LMD-006, LMD-022, LMD-029, LMD-044, LMD-045, LMD-046, LMD-051, and LMD-052) demonstrating equilibrium inhibition constants (Ki) of 6-16 nM in PD brain homogenates, all of which are amenable for radiolabeling with fluorine-18. This work advances the molecular toolkit for synucleinopathies and provides a roadmap for overcoming barriers in PET tracer development, with lead compounds that can be considered for biomarker-guided clinical trials and targeted therapies.

Keywords:  PET; Parkinson’s disease; structure-activity relationships; α-Synuclein

DOI:  https://doi.org/10.3390/cells14191531
Eur J Pharm Sci. 2025 Oct 10. pii: S0928-0987(25)00318-5. [Epub ahead of print]215 107320

Effect of temperature on the aggregation of an Fc-fusion protein under agitation.

Zekun Wang, Arni Gambe-Gilbuena, Satoru Unzai, Susumu Uchiyama, Tetsuo Torisu.

  Mitigating protein aggregation remains a challenge in the development of biopharmaceuticals, and agitation is well known as a stress that can induce protein aggregation. However, the temperature dependence of agitation-induced aggregation is not well understood. In this study, the aggregation of an Fc-fusion protein under agitation stress was investigated at 5, 25, and 40 °C. Soluble and insoluble aggregates were quantified by size-exclusion liquid chromatography and flow imaging microscopy, respectively. Both the aggregation level and the aggregate clusters were temperature dependent. The threshold for the orbital shaking that induced protein aggregation was temperature independent. Although thermal stress at 40 °C increased the number of oligomers, it did not lead to a higher monomer loss in a subsequent agitation at 25 °C. The aggregation induced by agitation stress was suppressed by adding a surfactant or removing the vial headspace, indicating that the aggregation occurred via an interface-mediated pathway. Thus, the observed temperature dependence was attributed to the protein adsorption to the interface and the following interfacial unfolding and aggregation was affected by the temperature. The results emphasized the importance of temperature control during shipping to ensure the quality of drug products. Agitation stability studies at a controlled temperature also provide a deep understanding of the protein aggregation mechanism, which is important for formulation development.

Keywords:  Agitation stress; Fc-fusion protein; Protein aggregation; Protein stability; Thermal stress

DOI:  https://doi.org/10.1016/j.ejps.2025.107320
EMBO J. 2025 Oct 17.

Direct interaction between TDP-43 and Tau promotes their co-condensation, while suppressing Tau fibril formation and seeding.

Francesca Simonetti, Weijia Zhong, Saskia Hutten, Federico Uliana, Martina Schifferer, Ali Rezaei, Lisa Marie Ramirez, Janine Hochmair, Rithika Sankar, Anusha Gopalan, Fridolin Kielisch, Henrick Riemenschneider, Viktoria Ruf, Carla Schmidt, Mikael Simons, Markus Zweckstetter, Susanne Wegmann, Tammaryn Lashley, Magdalini Polymenidou, Dieter Edbauer, Dorothee Dormann.

  Neuronal aggregates of Tau are a hallmark of Alzheimer's disease (AD), but more than half of the patients exhibit additional TDP-43 inclusions, while some have co-aggregates of the two proteins. The presence of such co-aggregates is associated with increased disease severity, although whether there is a causal relationship remains unclear. Here, we demonstrate that Tau and TDP-43 mutually promote each other's condensation through direct interaction in vitro, forming irregularly-shaped or multiphasic co-condensates with lower TDP-43 mobility, but higher Tau mobility. While Tau promotes TDP-43 aggregation in vitro, TDP-43 suppresses formation of Tau fibrils and instead causes formation of oligomeric Tau and Tau/TDP-43 species. These co-assemblies hinder Tau seeding in a biosensor assay specific for proteopathic Tau seeds. Consistent with these data, insoluble material extracted from AD patient brains with Tau/TDP-43 co-aggregates exhibits reduced Tau seeding compared to AD patient brains with Tau aggregates only. In contrast, patient-derived extracts from AD patient brains with Tau/TDP-43 co-aggregates are highly potent in seeding new TDP-43 aggregates in a TDP-43 reporter cell line. Our results suggest that direct interaction between TDP-43 and Tau may suppress Tau pathology, while promoting TDP-43 pathology in Alzheimer's disease patients.

Keywords:  Alzheimer’s Disease; Phase Separation; Seeding; TDP-43; Tau

DOI:  https://doi.org/10.1038/s44318-025-00590-2
Molecules. 2025 Sep 30. pii: 3930. [Epub ahead of print]30(19):

Multicomponent Synthesis of Multi-Target Quinazolines Modulating Cholinesterase, Oxidative Stress, and Amyloid Aggregation Activities for the Therapy of Alzheimer's Disease.

Saida Chakhari, José Marco-Contelles, Isabel Iriepa, Maria do Carmo Carreiras, Fakher Chabchoub, Lhassane Ismaili, Bernard Refouvelet.

  Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder characterized by extracellular accumulation of amyloid-beta (Aβ) peptide, intracellular neurofibrillary tangles (NFTs), severe neuronal loss, and a marked decline in cholinergic function. Due to the limited efficacy of currently available therapies, the search for new chemical scaffolds able to target multiple pathological mechanisms remains an urgent priority. Among the most promising strategies are heterocyclic frameworks that can simultaneously interact with cholinesterase (ChE) enzymes and inhibit amyloid-β (Aβ) aggregation while also exhibiting antioxidant activity. In this context, we report a series of quinazoline derivatives synthesized via a sequential, one-pot multicomponent reaction, in good yields. Several of these compounds demonstrated notable antioxidant properties, as well as inhibitory effects on ChE activity and Aβ1-42 self-aggregation, highlighting their potential as multifunctional agents for the treatment of neurodegenerative disorders. Notably, 2-ethyl-4-(3,4-Dimethoxyphenyl)aminoquinazoline (3h) demonstrated the most balanced biological profile among the tested compounds, exhibiting an ORAC value of 5.73 TE, an acetylcholinesterase (AChE) inhibition IC50 = 6.67 μM, and 36.68% inhibition of Aβ1-42 aggregation, closely approaching the activity of curcumin. These findings highlight compound 3h as a promising quinazoline-based hit for the development of multifunctional agents targeting AD.

Keywords:  ORAC; antioxidants; cholinesterase inhibitors; quinazoline

DOI:  https://doi.org/10.3390/molecules30193930
ACS Chem Neurosci. 2025 Oct 12.

Kinetic Mechanism of Heparin-Induced Fibrillation of α-Synuclein.

Takashi Ohgita, Norihiro Namba, Nao Minami, Hiroyuki Saito.

  Deposition of fibrillar aggregates of α-synuclein (αS) in the brain is a hallmark of αS-associated neurodegenerative diseases. Heparin, a structural analog of cell-surface heparan sulfate, modulates the kinetics of αS fibrillation and the morphology of the resulting fibrils. In this study, we investigated the kinetic mechanism of heparin-induced αS fibrillation using physicochemical techniques. Thioflavin T fluorescence and fibril-pelleting assays demonstrated that heparin greatly induces αS fibril formation and increases the mass of fibrillar αS in a concentration-dependent manner. Atomic force microscopy revealed that higher concentrations of heparin promote the formation of longer fibrils. These findings suggest that elongation of αS fibrils reaches a dynamic equilibrium during the plateau phase and that heparin shifts this equilibrium toward elongation. Considering the fibril dissociation process, we developed a kinetic model for heparin-induced αS fibrillation based on the process by which fibrillar αS inversely converts to a monomeric state. This model successfully captured the kinetic behavior of heparin-induced αS fibrillation and indicated that heparin promotes fibril growth by favoring elongation over dissociation. Overall, our study suggests the potential mechanism by which heparin promotes fibrillation of αS, highlighting the critical role of the equilibrium between fibril elongation and dissociation in αS fibrillation.

Keywords:  Amyloid fibrils; Fibril dissociation; Finke−Watzky model; Heparin; Neurodegenerative diseases; α-Synuclein

DOI:  https://doi.org/10.1021/acschemneuro.5c00489
ACS Omega. 2025 Oct 07. 10(39): 46115-46123

Optofluidic Waveguides for the Label-Free Study of Silk Protein Aggregates.

Jan R Heck, Zenon Toprakcioglu, Tobias E Naegele, Michael H Frosz, Tuomas P J Knowles, Tijmen G Euser.

Methods for studying protein aggregation are crucial to understanding the associated disease pathologies and for functional biomaterial synthesis in nature and in the laboratory. The ideal measurement platform is low-volume, label-free, and noncontact, as well as easily integrated into continuous-flow microfluidic experiments to provide scalability. Current approaches realize only a subset of these requirements. Here, we demonstrate a new technique for studying protein aggregates and in situ aggregation within hollow-core photonic crystal fibers. These optofluidic waveguides allow us to perform continuous-flow microfluidic label-free analysis of silk fibroin protein in the form of preformed nanofibrillar aggregates and on the native protein as it undergoes aggregation in situ in the optofluidic waveguide. We demonstrate label-free ultraviolet absorbance measurements on both calibration-standard nanospheres and silk fibroin aggregates as well as monitoring the aggregation of native silk fibroin protein solution via simultaneous ultraviolet absorbance and intrinsic fluorescence measurements in situ. This technique forms a platform for the study of protein aggregation that is low volume, label-free, and optical, thereby providing a valuable optofluidic tool for a range of protein biophysics.

DOI: https://doi.org/10.1021/acsomega.5c07826
Int J Mol Sci. 2025 Oct 07. pii: 9741. [Epub ahead of print]26(19):

Temporal Interactome Mapping of Human Tau in Drosophila Reveals Progressive Mitochondrial Engagement and Porin/VDAC1-Dependent Modulation of Toxicity.

Eleni Tsakiri, Martina Samiotaki, Efthimios M C Skoulakis, Katerina Papanikolopoulou.

  Tau protein misfolding and aggregation are central to Tauopathies, yet the temporal dynamics of Tau interactions in vivo remain poorly understood. Here, we applied quantitative proteomics to demonstrate that the interactome of human Tau in adult Drosophila brains changes dynamically over a 12-day time course, revealing a progressive shift from early cytosolic and ribosomal associations to late enrichment of mitochondrial and synaptic partners. Notably, the mitochondrial pore protein Porin/VDAC1 was identified as a late-stage interactor and functional analyses demonstrated that Tau overexpression impairs mitochondrial respiration, elevates oxidative damage, and disrupts carbohydrate homeostasis. To validate this temporally specific interaction, Porin was downregulated, resulting in reduced Tau mitochondrial association, phosphorylation and aggregation. Paradoxically, however, Porin attenuation exacerbated Tau-induced toxicity, including shortened lifespan, locomotor deficits, and impaired learning. These findings indicate that while Porin facilitates pathological Tau modifications, it is also essential for neuronal resilience, highlighting a complex role in modulating Tau toxicity. Our study provides a temporal map of Tau-associated proteome changes in vivo and identifies mitochondria as critical mediators of Tau-driven neurodegeneration.

Keywords:  Drosophila; Tau protein; mitochondria; porin; proteomics

DOI:  https://doi.org/10.3390/ijms26199741