bims-proned Biomed News
on Proteostasis in neurodegeneration
Issue of 2025–02–02
twenty papers selected by
Verena Kohler, Umeå University
  1. Peptide-based amyloid-beta aggregation inhibitors.
  2. Roles of C/EBPβ/AEP in Neurodegenerative Diseases.
  3. Interplay of p23 with FKBP51 and their chaperone complex in regulating tau aggregation.
  4. Novel Poly-Arginine Peptide R18D Reduces α-Synuclein Aggregation and Uptake of α-Synuclein Seeds in Cortical Neurons.
  5. Chaperones as Potential Pharmacological Targets for Treating Protein Aggregation Illness.
  6. Monoaminergic neurotransmitters are bimodal effectors of tau aggregation.
  7. Natural products against tau hyperphosphorylation-induced aggregates: Potential therapies for Alzheimer's disease.
  8. Tracing TMEM106B fibril deposition in aging and Parkinson's disease with dementia brains.
  9. Dehydroamino acids and their crosslinks in Alzheimer's disease aggregates.
  10. SynPull: An advanced method for studying neurodegeneration-related aggregates in synaptosomes using super-resolution microscopy.
  11. Distinct CSF α-synuclein aggregation profiles associated with Alzheimer's disease phenotypes and MCI-to-AD conversion.
  12. TDP-43 nuclear retention is antagonized by hypo-phosphorylation of its C-terminus in the cytoplasm.
  13. Small-molecule activators of NRF1 transcriptional activity prevent protein aggregation.
  14. Evaluating polyglutamine protein aggregation and toxicity in transgenic Caenorhabditis elegans models of Huntington's disease.
  15. A role for mitochondria-ER crosstalk in amyotrophic lateral sclerosis 8 pathogenesis.
  16. Sensitive detection and propagation of brain-derived tau assemblies in HEK293 based wild-type tau seeding assays.
  17. The ubiquitin-conjugating enzyme UBE2D maintains a youthful proteome and ensures protein quality control during aging by sustaining proteasome activity.
  18. Impact of Weak Vibration Generated by a Refrigerator on Protein Aggregation.
  19. Amyloid capture and aggregation inhibition by human serum albumin.
  20. Inhibition of Aβ Aggregation by Cholesterol-End-Modified PEG Vesicles and Micelles.
  1. RSC Med Chem. 2024 Dec 31.
    Peptide-based amyloid-beta aggregation inhibitors.
    Naina Sehra, Rajesh Parmar, Rahul Jain.
      Aberrant protein misfolding and accumulation is considered to be a major pathological pillar of neurodegenerative disorders, including Alzheimer's and Parkinson's diseases. Aggregation of amyloid-β (Aβ) peptide leads to the formation of toxic amyloid fibrils and is associated with cognitive dysfunction and memory loss in Alzheimer's disease (AD). Designing molecules that inhibit amyloid aggregation seems to be a rational approach to AD drug development. Over the years, researchers have utilized a variety of therapeutic strategies targeting different pathways, extensively studying peptide-based approaches to understand AD pathology and demonstrate their efficacy against Aβ aggregation. This review highlights rationally designed peptide/mimetics, including structure-based peptides, metal-peptide chelators, stapled peptides, and peptide-based nanomaterials as potential amyloid inhibitors.
    DOI:  https://doi.org/10.1039/d4md00729h
  2. Curr Top Med Chem. 2025 Jan 27.
    Roles of C/EBPβ/AEP in Neurodegenerative Diseases.
    Jing Guo, Xin-Yi Liu, Sha-Sha Yang, Qiang Li, Yang Duan, Shan-Shan Zhu, Ke Zhou, Yi-Zhi Yan, Peng Zeng.
      In recent years, an increasing number of studies have shown that increased activation of aspartic endopeptidases (AEPs) is a common symptom in neurodegenerative diseases (NDDs). AEP cleaves amyloid precursor protein (APP), tau (microtubule-associated protein tau), α- synuclein (α-syn), SET (a 39-KDa phosphoprotein widely expressed in various tissues and localizes predominantly in the nucleus), and TAR DNA-binding protein 43 (TDP-43), and promotes their aggregation, contributing to Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD) pathogenesis. Abundant evidence supports the notion that CCAAT/enhancer-binding protein β (C/EBPβ)/AEP may play an important role in NDDs. Developing its small molecule inhibitors is a promising treatment of NDDs. However, current research suggests that the pathophysiological mechanism of the C/EBPβ/AEP pathway is very complex in NDDs. This review summarizes the structure of C/EBPβ and AEP, their major physiological functions, potential pathogenesis, their small molecule inhibitors, and how C/EBPβ/AEP offers a novel pathway for the treatment of NDDs.
    Keywords:  C/EBPβ; Neurodegenerative diseases; asparagine endopeptidase; pathogenesis; small molecule inhibitors.
    DOI:  https://doi.org/10.2174/0115680266357822250119172351
  3. Nat Commun. 2025 Jan 14. 16(1): 669
    Interplay of p23 with FKBP51 and their chaperone complex in regulating tau aggregation.
    Pijush Chakraborty, Markus Zweckstetter.
      The pathological deposition of tau and amyloid-beta into insoluble amyloid fibrils are pathological hallmarks of Alzheimer's disease. Molecular chaperones are important cellular factors contributing to the regulation of tau misfolding and aggregation. Here we reveal an Hsp90-independent mechanism by which the co-chaperone p23 as well as a molecular complex formed by two co-chaperones, p23 and FKBP51, modulates tau aggregation. Integrating NMR spectroscopy, SAXS, molecular docking, and site-directed mutagenesis we reveal the structural basis of the p23-FKBP51 complex. We show that p23 specifically recognizes the TPR domain of FKBP51 and interacts with tau through its C-terminal disordered tail. We further show that the p23-FKBP51 complex binds tau to form a dynamic p23-FKBP51-tau trimeric complex that delays tau aggregation and thus may counteract Hsp90-FKBP51 mediated toxicity. Taken together, our findings reveal a co-chaperone mediated Hsp90-independent chaperoning of tau protein.
    DOI:  https://doi.org/10.1038/s41467-025-56028-0
  4. Biomedicines. 2025 Jan 07. pii: 122. [Epub ahead of print]13(1):
    Novel Poly-Arginine Peptide R18D Reduces α-Synuclein Aggregation and Uptake of α-Synuclein Seeds in Cortical Neurons.
    Emma C Robinson, Anastazja M Gorecki, Samuel R Pesce, Vaishali Bagda, Ryan S Anderton, Bruno P Meloni.
       BACKGROUND/OBJECTIVES: The role of α-synuclein (α-syn) pathology in Parkinson's disease (PD) is well established; however, effective therapies remain elusive. Two mechanisms central to PD neurodegeneration are the intracellular aggregation of misfolded α-syn and the uptake of α-syn aggregates into neurons. Cationic arginine-rich peptides (CARPs) are an emerging class of molecule with multiple neuroprotective mechanisms of action, including protein stabilisation. This study characterised both intracellular α-syn aggregation and α-syn uptake in cortical neurons in vitro. Thereafter, this study examined the therapeutic potential of the neuroprotective CARP, R18D (18-mer of D-arginine), to prevent the aforementioned PD pathogenic processes through a cell-free thioflavin-T (ThT) assay and in cortical neurons.
    METHODS: To induce intracellular α-syn aggregation, rat primary cortical neurons were exposed to α-syn seed (0.14 μM) for 2 h to allow uptake of the protein, followed by R18D treatment (0.0625, 0.125, 0.25, 0.5 μM), and a subsequent measurement of α-syn aggregates 48 h later using a homogenous time-resolved fluorescence (HTRF) assay. To assess neuronal uptake, α-syn seeds were covalently labelled with an Alexa-Fluor 488 fluorescent tag, pre-incubated with R18D (0.125, 0.25, 0.5 μM), and then exposed to cortical neurons for 24 h and assessed via confocal microscopy.
    RESULTS: It was demonstrated that R18D significantly reduced both intracellular α-syn aggregation and α-syn seed uptake in neurons by 37.8% and 77.7%, respectively. Also, R18D reduced the aggregation of α-syn monomers in the cell-free assay.
    CONCLUSIONS: These findings highlight the therapeutic potential of R18D to inhibit key α-syn pathological processes and PD progression.
    Keywords:  Parkinson’s disease; R18D; cationic arginine-rich peptides; primary cortical neurons; α-synuclein; α-synuclein seeds
    DOI:  https://doi.org/10.3390/biomedicines13010122
  5. Curr Protein Pept Sci. 2025 Jan 27.
    Chaperones as Potential Pharmacological Targets for Treating Protein Aggregation Illness.
    Shikha Rani, Minkal Tuteja.
      The three-dimensional structure of proteins, achieved through the folding of the nascent polypeptide chain in vivo, is largely facilitated by molecular chaperones, which are crucial for determining protein functionality. In addition to aiding in the folding process, chaperones target misfolded proteins for degradation, acting as a quality control system within the cell. Defective protein folding has been implicated in a wide range of clinical conditions, including neurodegenerative and metabolic disorders. It is now well understood that the pathogenesis of neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, Huntington's disease, Amyotrophic Lateral Sclerosis, and Creutzfeldt-Jakob disease shares a common mechanism: the accumulation of misfolded proteins, which aggregate and become toxic to cells. Among the family of molecular chaperones, Heat Shock Proteins (HSPs) are highly expressed in response to cellular stress and play a pivotal role in preventing protein aggregation. Specific chaperones, particularly HSPs, are now recognized as critical in halting the accumulation and aggregation of misfolded proteins in these conditions. Consequently, these chaperones are increasingly considered promising pharmacological targets for the treatment of protein aggregation-related diseases. This review highlights research exploring the potential roles of specific molecular chaperones in disorders characterized by the accumulation of misfolded proteins.
    Keywords:  Protein folding; aggregates; and therapeutic targets; chaperone therapy; conformational disorders; misfolding
    DOI:  https://doi.org/10.2174/0113892037338028241230092414
  6. Sci Adv. 2025 Jan 31. 11(5): eadr8055
    Monoaminergic neurotransmitters are bimodal effectors of tau aggregation.
    Xinmin Chang, Amanda M Tse, Marina Fayzullina, Angela Albanese, Minchan Kim, Conner F Wang, Zipeng Zheng, Ruchira V Joshi, Christopher K Williams, Shino D Magaki, Harry V Vinters, Jeremy O Jones, Ian S Haworth, Paul M Seidler.
      Neurotransmitters (NTs) mediate trans-synaptic signaling, and disturbances in their levels are linked to aging and brain disorders. Here, we ascribe an additional function for NTs in mediating intracellular protein aggregation by interaction with cytosolic protein fibrils. Cell-based seeding experiments revealed monoaminergic NTs as inhibitors of tau. Seeding is a disease-relevant mechanism involving catalysis by fibrils, leading to the aggregation of proteins in Alzheimer's disease and other neurodegenerative diseases. Chemotyping small molecules with varied backbone structures revealed determinants of aggregation inhibitors and catalysts. Among those identified were monoaminergic NTs. Dose titrations revealed bimodal effects indicative of fibril disaggregation, with aggregation catalysis occurring at low ratios of NTs and inhibited seeding ensuing at higher concentrations. Bimodal effects by NTs extend from in vitro systems to dopaminergic neurons, suggesting that pharmacotherapies that modify intracellular NT levels could shape the neuronal protein aggregation environment.
    DOI:  https://doi.org/10.1126/sciadv.adr8055
  7. Arch Pharm (Weinheim). 2025 Jan;358(1): e2400721
    Natural products against tau hyperphosphorylation-induced aggregates: Potential therapies for Alzheimer's disease.
    Gustavo Basurto-Islas, Maximiliano Caye Diaz, Lizeth M Zavala Ocampo, Melchor Martínez-Herrera, Perla Y López-Camacho.
      Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline and memory impairments and is considered the most prevalent form of dementia. Among the contributing factors to AD lies the hyperphosphorylation of the microtubule-associated protein tau. Phosphorylated tau reduces its affinity for microtubules and triggers other posttranslational modifications that result in its aggregation and assembly into filaments. These structures progressively accumulate within neurons leading to neurodegeneration. While current AD medications often involve undesirable side effects, the exploration of natural products as a potential therapeutic alternative has gained considerable attention. Numerous compounds have shown potential capacity for reducing tau pathology through different mechanisms, such as inhibiting kinases to reduce tau hyperphosphorylation, enhancing phosphatase activity, and blocking fibril formation. Since tau hyperphosphorylation-induced aggregation is pivotal in AD onset, this review aims to elucidate the potential of natural products in modulating this crucial molecular mechanism.
    Keywords:  Alzheimer's disease; dementia; plant extract; tau fibrils; tau phosphorylation
    DOI:  https://doi.org/10.1002/ardp.202400721
  8. Life Med. 2024 Feb;3(1): lnae011
    Tracing TMEM106B fibril deposition in aging and Parkinson's disease with dementia brains.
    Wanbing Zhao, Yun Fan, Qinyue Zhao, Zhen Fan, Jue Zhao, Wenbo Yu, Wensheng Li, Dan Li, Cong Liu, Jian Wang.
      Transmembrane protein 106B (TMEM106B), previously identified as a risk factor in frontotemporal lobar degeneration, has recently been detected to form fibrillar aggregates in the brains of patients with various neurodegenerative diseases (NDs) and normal elders. While the specifics of when and where TMEM106B fibrils accumulate in human brains, as well as their connection to aging and disease progression, remain poorly understood. Here, we identified an antibody (NBP1-91311) that directly binds to TMEM106B fibrils extracted from the brain in vitro and to Thioflavin S-positive TMEM106B fibrillar aggregates in brain sections. We discovered that TMEM106B fibrils deposit in the human brain in an age-dependent manner. Notably, the TMEM106B fibril load in the brains of Parkinson's disease with dementia patients was significantly higher than in age-matched elders. Additionally, we found that TMEM106B fibrils predominantly accumulate in astrocytes and neurons and do not co-localize with the pathological deposition formed by other amyloid proteins such as α-synuclein, Aβ, and Tau. Our work provides a comprehensive analysis of the burden and cellular distribution of TMEM106B fibrils in human brains, underscoring the impact of both aging and disease conditions on TMEM106B fibril deposition. This highlights the potential significance of TMEM106B fibrils in various age-related NDs.
    Keywords:  Parkinson’s disease with dementia; TMEM106B fibril; aging; amyloid aggregation; neurodegenerative disease
    DOI:  https://doi.org/10.1093/lifemedi/lnae011
  9. Brain Commun. 2025 ;7(1): fcaf019
    Dehydroamino acids and their crosslinks in Alzheimer's disease aggregates.
    Samuel W Markovich, Brian L Frey, Mark Scalf, Michael R Shortreed, Lloyd M Smith.
      Alzheimer's disease (AD) is characterized by the accumulation of protein aggregates, which are thought to be influenced by posttranslational modifications (PTMs). Dehydroamino acids (DHAAs) are rarely observed PTMs that contain an electrophilic alkene capable of forming protein-protein crosslinks, which may lead to protein aggregation. We report here the discovery of DHAAs in the protein aggregates from AD, constituting an unknown and previously unsuspected source of extensive proteomic complexity. We used mass spectrometry-based proteomics to discover 404 sites of DHAA formation in 171 proteins from protein aggregate-enriched human brain samples, 6-fold more sites than observed in the soluble protein fractions. The DHAA modifications are observed both directly and in the form of conjugates after reacting with abundant cellular nucleophiles or crosslinking to nucleophilic amino acid residues. We report 11 such crosslinks, including three in the Tau protein, which are 10-fold more abundant in AD samples compared with age-matched controls. Many of the proteins found to contain DHAAs and their conjugates are involved in protein aggregation or pathways dysregulated in AD. DHAAs are prevalent modifications in the AD brain proteome and give rise to protein crosslinks that may contribute to protein aggregation.
    Keywords:  Tau; myelin; neurofibrillary tangles; posttranslational modification; protein aggregation
    DOI:  https://doi.org/10.1093/braincomms/fcaf019
  10. Cell Chem Biol. 2025 Jan 23. pii: S2451-9456(25)00001-7. [Epub ahead of print]
    SynPull: An advanced method for studying neurodegeneration-related aggregates in synaptosomes using super-resolution microscopy.
    Shekhar Kedia, Emre Fertan, Yunzhao Wu, Yu P Zhang, Georg Meisl, Jeff Y L Lam, Frances K Wiseman, William A McEwan, Annelies Quaegebeur, Maria Grazia Spillantini, John S H Danial, David Klenerman.
      Synaptic dysfunction is a primary hallmark of both Alzheimer's and Parkinson's disease, leading to cognitive and behavioral decline. While alpha-synuclein, beta-amyloid, and tau are involved in the physiological functioning of synapses, their pathological aggregation has been linked to synaptopathology. The methodology for studying the small-soluble protein aggregates formed by these proteins is limited. Here we describe SynPull, a method combining single-molecule pull-down, super-resolution microscopy, and advanced computational analyses to characterize the protein aggregates in human and mouse synaptosomes. We show that AT8-positive tau aggregates are the predominant aggregate type in synaptosomes from postmortem Alzheimer's disease brain, although the aggregate size does not change in disease. Meanwhile, the relatively smaller amount of alpha-synuclein and beta-amyloid aggregates found in the synapses are larger than the extra-synaptic ones. Collectively, these results show the utility of SynPull to study pathological aggregates in neurodegeneration, elucidating the disease mechanisms causing synaptic dysfunction.
    Keywords:  Alzheimer's disease; Parkinson's disease; dSTORM; data modelling; dementia; mouse model; single-molecule detection; soluble aggregates; super-resolution microscopy; synapse
    DOI:  https://doi.org/10.1016/j.chembiol.2025.01.001
  11. J Prev Alzheimers Dis. 2025 Feb;pii: S2274-5807(24)00632-0. [Epub ahead of print]12(2): 100040
    Distinct CSF α-synuclein aggregation profiles associated with Alzheimer's disease phenotypes and MCI-to-AD conversion.
    Alzheimer's Disease Neuroimaging Initiative (ADNI)
       BACKGROUND: α-Synuclein (α-Syn) pathology is present in 30-50 % of Alzheimer's disease (AD) patients, and its interactions with tau proteins may further exacerbate pathological changes in AD. However, the specific role of different aggregation forms of α-Syn in the progression of AD remains unclear.
    OBJECTIVES: To explore the relationship between various aggregation types of CSF α-Syn and Alzheimer's disease progression.
    DESIGN: We conducted a retrospective analysis of data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) to examine the association between different α-Syn aggregation forms-Syn0 (no detectable α-Syn aggregates) and Syn1 (α-Syn aggregates detected, resembling those found in Parkinson's disease)-with the pathological and clinical features of AD. Additionally, we evaluated their potential as predictors of conversion from mild cognitive impairment (MCI) to AD.
    SETTING: The ADNI database.
    PARTICIPANTS: A total of 250 participants, including 70 cognitively normal controls, 119 patients diagnosed with MCI, and 61 patients diagnosed with AD.
    MEASUREMENTS: Pearson correlation was employed to assess the relationship between α-Syn levels and cerebrospinal fluid (CSF) biomarkers, including total tau (T-tau), phosphorylated tau (p-tau), and amyloid-β42 (Aβ42). Multivariate Cox proportional hazards models were applied, adjusting for APOE4 status, age, and sex, to determine the association between α-Syn forms and AD-related pathological and clinical outcomes. Kaplan-Meier curves were used to evaluate the prognostic value of different α-Syn aggregation states in predicting the conversion from MCI to AD.
    RESULTS: Compared with controls, overall MCI and AD patients had elevated α-Syn levels. Notably, in the α-Syn0 group, α-Syn levels were increased in the MCI patients and further increased in AD patients, whereas in the α-Syn1 group, α-Syn levels did not significantly differ across diagnostic groups. Both in the α-Syn0 and α-Syn1 groups, α-Syn levels were found to correlate more strongly with CSF tau levels than with Aβ42, indicating a possible role for α-Syn in tau-related pathology in AD. Importantly, α-Syn0-AD patients exhibited more rapid cognitive decline and greater hippocampal atrophy than α-Syn1-AD patients. However, MCI patients with CSF α-Syn1 aggregation status had an increased risk of conversion to AD.
    CONCLUSIONS: CSF α-Syn is associated with tau pathology and neurodegeneration in Alzheimer's disease. The distinct aggregation profiles of α-Syn serve as valuable biomarkers, offering insights into differing prognoses in AD and aiding in the prediction of early disease progression.
    Keywords:  Alzheimer's disease; Cerebrospinal fluid; Mild cognitive impairment; α-Synuclein
    DOI:  https://doi.org/10.1016/j.tjpad.2024.100040
  12. Commun Biol. 2025 Jan 28. 8(1): 136
    TDP-43 nuclear retention is antagonized by hypo-phosphorylation of its C-terminus in the cytoplasm.
    Célia Rabhi, Nicolas Babault, Céline Martin, Bénédicte Desforges, Alexandre Maucuer, Vandana Joshi, Serhii Pankivskyi, Yitian Feng, Guillaume Bollot, Revital Rattenbach, David Pastré, Ahmed Bouhss.
      Protein aggregation is a hallmark of many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), in which TDP-43, a nuclear RNA-binding protein, forms cytoplasmic inclusions. Here, we have developed a robust and automated method to assess protein self-assembly in the cytoplasm using microtubules as nanoplatforms. Importantly, we have analyzed specifically the self-assembly of full-length TDP-43 and its mRNA binding that are regulated by the phosphorylation of its self-adhesive C-terminus, which is the recipient of many pathological mutations. We show that C-terminus phosphorylation prevents the recruitment of TDP-43 in mRNA-rich stress granules only under acute stress conditions because of a low affinity for mRNA but not under mild stress conditions. In addition, the self-assembly of the C-terminus is negatively regulated by phosphorylation in the cytoplasm which in turn promotes TDP-43 nuclear import. We anticipate that reducing TDP-43 C-terminus self-assembly in the cytoplasm may be an interesting strategy to reverse TDP-43 nuclear depletion in neurodegenerative diseases.
    DOI:  https://doi.org/10.1038/s42003-025-07456-7
  13. Biomed Pharmacother. 2025 Jan 28. pii: S0753-3322(25)00058-7. [Epub ahead of print]183 117864
    Small-molecule activators of NRF1 transcriptional activity prevent protein aggregation.
    Jindrich Sedlacek, Zuzana Smahelova, Michael Adamek, Dominika Subova, Lucie Svobodova, Alena Kadlecova, Pavel Majer, Ales Machara, Klara Grantz Saskova.
      Intracellular protein aggregation causes proteotoxic stress, underlying highly debilitating neurodegenerative disorders in parallel with decreased proteasome activity. Nevertheless, under such stress conditions, the expression of proteasome subunits is upregulated by Nuclear Factor Erythroid 2-related factor 1 (NRF1), a transcription factor that is encoded by NFE2L1. Activating the NRF1 pathway could accordingly delay the onset of neurodegenerative and other disorders with impaired cell proteostasis. Here, we present a series of small-molecule compounds based on bis(phenylmethylen)cycloalkanones and their heterocyclic analogues, identified via targeted library screening, that can induce NRF1-dependent downstream events, such as proteasome synthesis, heat shock response, and autophagy, in both model cell lines and Caenorhabditis elegans strains. These compounds increase proteasome activity and decrease the size and number of protein aggregates without causing any cellular stress or inhibiting the ubiquitin-proteasome system (UPS). Therefore, our compounds represent a new promising therapeutic approach for various protein conformational diseases, including the most debilitating neurodegenerative diseases.
    Keywords:  DDI2; NGLY1; NRF1(NFE2L1); Proteasome; Protein aggregates; Small molecules
    DOI:  https://doi.org/10.1016/j.biopha.2025.117864
  14. Methods Cell Biol. 2025 ;pii: S0091-679X(24)00168-7. [Epub ahead of print]192 115-130
    Evaluating polyglutamine protein aggregation and toxicity in transgenic Caenorhabditis elegans models of Huntington's disease.
    Larissa Marafiga Cordeiro, Félix Alexandre Antunes Soares, Leticia Priscilla Arantes.
      Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by a repeat of the cytosine-adenine-guanine trinucleotide (CAG) in the huntingtin gene (HTT). This results in the translation of a mutant huntingtin (mHTT) protein with an abnormally long polyglutamine (polyQ) repeat. The pathology of HD leads to neuronal cell loss, motor abnormalities, and dementia. Currently, the pathogenesis of HD remains incompletely understood, and available treatments only address symptoms. Caenorhabditis elegans has been used as a model for neurodegenerative diseases, enabling the exploration of the molecular, cellular, and physiological mechanisms underlying HD pathogenesis. It also facilitates the investigation of potential therapeutic targets and interventions. Here, we describe common experiments employed to assess polyQ aggregation and toxicity in transgenic C. elegans models of HD, utilizing fluorescent markers to detect protein aggregation and neuron degeneration, in addition to specific behavioral assays (thrash frequency, nose touch response, and octanol response).
    Keywords:  Animal model; Drug discovery; Genetic screening; Huntingtin; Neurodegenerative disease
    DOI:  https://doi.org/10.1016/bs.mcb.2024.06.002
  15. Life Sci Alliance. 2025 Apr;pii: e202402907. [Epub ahead of print]8(4):
    A role for mitochondria-ER crosstalk in amyotrophic lateral sclerosis 8 pathogenesis.
    Cathal Wilson, Laura Giaquinto, Michele Santoro, Giuseppe Di Tullio, Valentina Morra, Wanda Kukulski, Rossella Venditti, Francesca Navone, Nica Borgese, Maria Antonietta De Matteis.
      Protein aggregates in motoneurons, a pathological hallmark of amyotrophic lateral sclerosis, have been suggested to play a key pathogenetic role. ALS8, characterized by ER-associated inclusions, is caused by a heterozygous mutation in VAPB, which acts at multiple membrane contact sites between the ER and almost all other organelles. The link between protein aggregation and cellular dysfunction is unclear. A yeast model, expressing human mutant and WT-VAPB under the control of the orthologous yeast promoter in haploid and diploid cells, was developed to mimic the disease situation. Inclusion formation was found to be a developmentally regulated process linked to mitochondrial damage that could be attenuated by reducing ER-mitochondrial contacts. The co-expression of the WT protein retarded P56S-VAPB inclusion formation. Importantly, we validated these results in mammalian motoneuron cells. Our findings indicate that (age-related) damage to mitochondria influences the propensity of the mutant VAPB to form aggregates via ER-mitochondrial contacts, initiating a series of events leading to disease progression.
    DOI:  https://doi.org/10.26508/lsa.202402907
  16. J Biol Chem. 2025 Jan 27. pii: S0021-9258(25)00092-4. [Epub ahead of print] 108245
    Sensitive detection and propagation of brain-derived tau assemblies in HEK293 based wild-type tau seeding assays.
    Melissa Huang, William A McEwan.
      The assembly of tau into filaments defines tauopathies, a group of neurodegenerative diseases including Alzheimer's disease (AD), Pick's disease (PiD), corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP). The seeded aggregation of tau has been modelled in cell culture using pro-aggregant modifications such as truncation of N- and C-termini and point-mutations within the microtubule-binding repeat domain. This limits the applicability of research findings to sporadic disease, where aggregates contain wild-type, full-length tau. We aimed to develop sensitive and specific biosensor assays for brain-derived tau species utilizing 0N3R and 0N4R tau expressed in HEK293 cells. We further generate a cell line that propagates insoluble tau which is hyperphosphorylated at disease relevant sites and retains a seeding profile similar to AD. We propose these systems as an advance over existing cell-based seeding assays, as they display specificity to the conformation and isoform composition of sporadic human disease.
    DOI:  https://doi.org/10.1016/j.jbc.2025.108245
  17. PLoS Biol. 2025 Jan;23(1): e3002998
    The ubiquitin-conjugating enzyme UBE2D maintains a youthful proteome and ensures protein quality control during aging by sustaining proteasome activity.
    Liam C Hunt, Michelle Curley, Kudzai Nyamkondiwa, Anna Stephan, Jianqin Jiao, Kanisha Kavdia, Vishwajeeth R Pagala, Junmin Peng, Fabio Demontis.
      Ubiquitin-conjugating enzymes (E2s) are key for protein turnover and quality control via ubiquitination. Some E2s also physically interact with the proteasome, but it remains undetermined which E2s maintain proteostasis during aging. Here, we find that E2s have diverse roles in handling a model aggregation-prone protein (huntingtin-polyQ) in the Drosophila retina: while some E2s mediate aggregate assembly, UBE2D/effete (eff) and other E2s are required for huntingtin-polyQ degradation. UBE2D/eff is key for proteostasis also in skeletal muscle: eff protein levels decline with aging, and muscle-specific eff knockdown causes an accelerated buildup in insoluble poly-ubiquitinated proteins (which progressively accumulate with aging) and shortens lifespan. Mechanistically, UBE2D/eff is necessary to maintain optimal proteasome function: UBE2D/eff knockdown reduces the proteolytic activity of the proteasome, and this is rescued by transgenic expression of human UBE2D2, an eff homolog. Likewise, human UBE2D2 partially rescues the lifespan and proteostasis deficits caused by muscle-specific effRNAi and re-establishes the physiological levels of effRNAi-regulated proteins. Interestingly, UBE2D/eff knockdown in young age reproduces part of the proteomic changes that normally occur in old muscles, suggesting that the decrease in UBE2D/eff protein levels that occurs with aging contributes to reshaping the composition of the muscle proteome. However, some of the proteins that are concertedly up-regulated by aging and effRNAi are proteostasis regulators (e.g., chaperones and Pomp) that are transcriptionally induced presumably as part of an adaptive stress response to the loss of proteostasis. Altogether, these findings indicate that UBE2D/eff is a key E2 ubiquitin-conjugating enzyme that ensures protein quality control and helps maintain a youthful proteome composition during aging.
    DOI:  https://doi.org/10.1371/journal.pbio.3002998
  18. AAPS J. 2025 Jan 27. 27(1): 34
    Impact of Weak Vibration Generated by a Refrigerator on Protein Aggregation.
    Shinji Kizuki, Zekun Wang, Satoru Yamauchi, Tetsuo Torisu, Susumu Uchiyama.
      Protein aggregates and particles in biopharmaceuticals can induce adverse immune responses in patients. Thus, suppression of the formation of protein aggregates and particles is important for the successful development of therapeutic proteins. Mechanical stresses, including agitation, are widely recognized as stress factors that generate protein aggregates and particles. However, although refrigerators and storage chambers generate weak vibration, there have been no studies of the impact of such weak vibration on aggregate and particle formation during storage. In this study, monomer loss and aggregate formation of a CTLA4-Ig were evaluated during storage in a refrigerator (having a vibration acceleration less than 0.006 G) with or without three vibration isolators. The vibration isolators reduced the vibration acceleration, thereby decreasing the rate of monomer loss and nanometer-sized aggregate formation. The increase in the aggregation rate due to the weak vibration was not mitigated by adding poloxamer 188 or eliminating the air-liquid interface, which are processes known to be effective in preventing protein aggregation due to mechanical stresses. Thus, reducing vibration should be an effective way to mitigate the risk of aggregate formation.
    Keywords:  biopharmaceutical characterization; physical stability; protein aggregation; vibration
    DOI:  https://doi.org/10.1208/s12248-025-01014-z
  19. Int J Biol Macromol. 2025 Jan 27. pii: S0141-8130(25)00916-X. [Epub ahead of print]301 140367
    Amyloid capture and aggregation inhibition by human serum albumin.
    Diego Cora, Wajih Al-Soufi, Mercedes Novo.
      Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by amyloid-beta (Aβ) aggregation, primarily involving the peptides Aβ40 and Aβ42. Human serum albumin (HSA) has emerged as a potential therapeutic agent due to its ability to bind Aβ, inhibit aggregation, and promote disaggregation. This study quantitatively examined the interactions of HSA with both monomeric and aggregated forms of Aβ40 and Aβ42 using fluorescence techniques, including bulk steady-state fluorescence, fluorescence anisotropy, time-resolved fluorescence, and Fluorescence Correlation Spectroscopy (FCS). The binding constants determined from these methods were 4.45 × 104 M-1 for Aβ42 and 1.8 × 104M-1 for Aβ40, indicating strong but differential affinities. FCS demonstrated that HSA effectively dissociates Aβ aggregates, shifting the equilibrium toward monomeric states, with the disaggregation capacity positively correlated with HSA concentration. These findings support HSA's utility in therapies like plasma exchange to reduce the cerebral Aβ burden, providing critical insights into its mechanistic role and therapeutic potential.
    Keywords:  Aggregation; Alzheimer's disease; Amyloid; FCS; Fluorescence; Fluorescence correlation spectroscopy; HSA; Human serum albumin; Supramolecular association
    DOI:  https://doi.org/10.1016/j.ijbiomac.2025.140367
  20. Pharmaceutics. 2024 Dec 24. pii: 1. [Epub ahead of print]17(1):
    Inhibition of Aβ Aggregation by Cholesterol-End-Modified PEG Vesicles and Micelles.
    Shota Watanabe, Motoki Ueda, Shoichiro Asayama.
      Background/Objectives: This study aimed to design and evaluate Chol-PEG2000 micelles and Chol-PEG500 vesicles as drug delivery system (DDS) carriers and inhibitors of amyloid-β (Aβ) aggregation, a key factor in Alzheimer's disease (AD). Methods: The physical properties of Chol-PEG assemblies were characterized using dynamic light scattering (DLS), electrophoretic light scattering (ELS), and transmission electron microscopy (TEM). Inhibitory effects on Aβ aggregation were assessed via thioflavin T (ThT) assay, circular dichroism (CD) spectroscopy, and native polyacrylamide gel electrophoresis (native-PAGE). Results: Chol-PEG2000 micelles and Chol-PEG500 vesicles were found to exhibit diameters of 20-30 nm and 70-80 nm, respectively, with neutral surface charges and those physical properties indicated the high affinity for Aβ. At a 10-fold molar ratio, thioflavin T (ThT) assay revealed that Chol-PEG2000 delayed Aβ fibril elongation by 20 hours, while Chol-PEG500 delayed it by 40 hours against Aβ peptide. At a 50-fold molar ratio, both Chol-PEG2000 and Chol-PEG500 significantly inhibited Aβ aggregation, as indicated by minimal fluorescence intensity increases over 48 hours. CD spectroscopy indicated that Aβ maintained its random coil structure in the presence of Chol-PEG assemblies at a 50-fold molar ratio. Native-PAGE analysis demonstrated a retardation in Aβ migration immediately after mixing with Chol-PEG assemblies, suggesting complex formation. However, this retardation disappeared within 5 min, implying rapid dissociation of the complexes. Conclusions: This study demonstrated that Chol-PEG500 vesicles more effectively inhibit Aβ aggregation than Chol-PEG2000 micelles. Chol-PEG assemblies perform as DDS carriers to be capable of inhibiting Aβ aggregation. Chol-PEG assemblies can deliver additional therapeutics targeting other aspects of AD pathology. This dual-function platform shows promise as both a DDS carrier and a therapeutic agent, potentially contributing to a fundamental cure for AD.
    Keywords:  Alzheimer’s disease; Aβ aggregation; cholesterol-end-modified PEG (Chol-PEG); drug delivery carrier; micelle; vesicle
    DOI:  https://doi.org/10.3390/pharmaceutics17010001
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