bims-amyloi 2026-08-02 papers

bims-amyloi

Biomed News

on Amyloid

Issue of 2026–08–02
twenty papers selected by
Alexander Röntgen, University of Cambridge

FAIM Inhibits Insulin Amyloidogenesis through a Noncanonical Aggregation Pathway.
Shrinking of Extracellular Space During Metabolic Stress Accelerates Amyloid-β Aggregation.
From Hummingbird to Elephant: Amyloid Formation in Natural Transthyretin Variants.
Leveraging Supramolecular Polymers to Induce the Targeted Protein Degradation of α-Synuclein.
Aggregation of Amyloid-like Peptides in Different Solvents.
Cholesterol at the Center of Alzheimer's Disease: A Unifying Hypothesis on the Pathogenic Mechanism.
Psoralen and Seselin Stabilize the α-helix Structure in Lysozyme and Inhibit the α-helix to β-sheet Exchange: An Efficient Anti-Amyloidogenic Mechanism.
Distinctive properties of the prion protein in the brain and retina in the amyloidosis associated with the PRNP F198S Mutation.
Mass Spectrometric Characterization of Native Insulin Hexamers and Non-Native Heptamers: Formation and Stability Across Insulin Analogs.
Antiamyloid Antibody Effects on Aβ-42 Protein Aggregates Profiled Using Nanospectroscopy.
Low-Intensity Focused Ultrasound Alters Alzheimer's Disease Pathology, In Vivo, as a Function of Ultrasound Dose and Age.
Munc18 reprograms the intrinsic neuronal SNARE complex assembly pathway.
A New Anatomy of Autophagic Clearance: On the Roles of Intrinsic Disorder in the Membrane-Less on Membrane-Encapsulated Mechanism.
α-Synuclein pathology differentially alters T-type calcium currents in vulnerable and resilient substantia nigra dopaminergic subpopulations.
Where does excessive beta in Parkinson's disease originate? Insights from a case of unilateral cortico-pallidal pathway dysfunction.
MicroRNA-223 Enhances Microglia-Dependent Clearance of Amyloid Beta Plaques and Ameliorates Behavioral Deficits in a Mouse Model of Alzheimer's Disease.
Astrocyte-driven small vessel disease is an early, amyloid-independent feature of PSEN1 E280A familial Alzheimer's disease.
Structural Transitions of β-lactoglobulin Aggregates Observed Under Controlled Heat Treatment.
Polyphenolic Imidazopyridines as Multifunctional Modulators of Oxidative Stress, Metal Dyshomeostasis, and β1-42 Amyloid Aggregation in an In Vitro Model of Alzheimer's Disease.
Neuroinflammation in Alzheimer's and Parkinson's diseases: pathogenic mechanisms and therapeutic strategies.

bioRxiv. 2026 Jul 14. pii: 2026.07.13.738277. [Epub ahead of print]

FAIM Inhibits Insulin Amyloidogenesis through a Noncanonical Aggregation Pathway.

Dana Wolfe, Jhinuk Saha, Joshua Mitchell, Sam McCalpin, Michael Gutknecht, Charles L Brooks, Thomas L Rothstein, Ayyalusamy Ramamoorthy.

Insulin can misfold and assemble into amyloid fibrils, a process linked not only to complications of insulin therapy but also to proteotoxic stress in pancreatic β-cells. Despite growing interest in the pathological consequences of insulin aggregation, prevention efforts are limited by an incomplete understanding of the endogenous mechanisms that counteract it. Here, we identify Fas apoptosis inhibitory molecule (FAIM) as an endogenous suppressor of insulin amyloid formation. FAIM reduces β-sheet formation and redirects insulin toward disordered, growth-incompetent assemblies. Further, FAIM attenuates the cytotoxicity of insulin aggregates in vitro . We hypothesize that this effect arises from masking aggregation-prone regions of insulin and show through structural modeling that FAIM interacts with both insulin chains. These findings extend the anti-aggregation function of FAIM to insulin and suggest a mechanism for endogenous suppression of insulin amyloid formation. More broadly, our results provide insight into the regulation of insulin assembly and highlight FAIM as a candidate modulator of proteostasis in metabolic disease.
Statement for a broader audience: Insulin can clump together into harmful aggregates, contributing to complications of insulin therapy and potentially damaging the insulin-producing cells of the pancreas. This study identifies the naturally occurring protein FAIM as a protective factor that inhibits the formation of these harmful aggregates and reduces their toxicity. These findings improve our understanding of how cells protect insulin from harmful aggregation and may open new avenues for developing therapies to combat diabetes-related protein aggregation.

DOI: https://doi.org/10.64898/2026.07.13.738277
Biomolecules. 2026 Jul 18. pii: 1053. [Epub ahead of print]16(7):

Shrinking of Extracellular Space During Metabolic Stress Accelerates Amyloid-β Aggregation.

Laura F De Oliveira, Kanchana Karunarathne, Dalton Zona, Martin Muschol, Ghanim Ullah.

  Pathological states associated with metabolic stress, such as traumatic brain injury (TBI), hypoxia, ischemic stroke, and migraine, are considered elevated risk factors for developing Alzheimer's disease (AD). However, the mechanism underlying the effect of these conditions on the progression of AD remains largely unknown. Here, we determine how metabolic stress associated with spreading depolarization (SD)-a hallmark of stroke, hypoxia, TBI, and migraine-modulates amyloid β (Aβ42) aggregation kinetics through dynamic changes in extracellular space (ECS). To achieve this, we used ThT fluorescence to determine how the formation of different Aβ42 aggregate species depends on Aβ42 concentrations. Based on this input, we build a multiscale computational framework that integrates volume regulation, including its dependence on neuronal ion homeostasis, and Aβ42 aggregation kinetics. Our model predicts that neuronal swelling during SD accelerates aggregation, where the impact of metabolic stress is highly dependent on the timing relative to aggregation progression and the initial monomer concentration. At low monomer concentrations, early SD events promote off-pathway oligomer formation, while at higher concentrations they rapidly drive fibril formation to saturation. In the absence of mature fibrils, recurrent metabolic stress events further amplify oligomer accumulation, whereas pre-existing fibril nuclei suppress oligomer formation at the expense of fibril nucleation and growth. Increasing the intensity of metabolic stress prolongs ECS shrinkage and enhances oligomer formation. These findings reveal a mechanistic link between SD-induced microenvironmental changes and Aβ aggregation dynamics, providing a quantitative framework for understanding how acute brain injury and metabolic stress may contribute to early AD pathogenesis.

Keywords:  Alzheimer’s disease; Amyloid β; aggregation; metablic stress; spreading depolarization

DOI:  https://doi.org/10.3390/biom16071053
bioRxiv. 2026 Jul 15. pii: 2026.07.09.737598. [Epub ahead of print]

From Hummingbird to Elephant: Amyloid Formation in Natural Transthyretin Variants.

Irina Ritsch, Daniel Scholl, Maria Rafiq, Maria A Martinez-Yamout, Gabriel C Lander, H Jane Dyson, Peter E Wright.

Transthyretin (TTR) is a secreted protein associated with cardiac and other amyloid diseases via misfolding. We have previously shown that agitation of human TTR solutions at neutral pH results in aggregation and fibril formation. Here we report that agitation-induced aggregation of TTR from species with very different heart rates (Anna's hummingbird, hbTTR, and African elephant, aeTTR) differs from that of human TTR (huTTR). Aggregation of hbTTR is slow and favors formation of smaller, fibrillar aggregates, while aeTTR aggregation is rapid and favors larger, more amorphous particles. Spherical, early-stage oligomeric intermediates were found for all variants by mass photometry and electron microscopy. The slow aggregation of hbTTR matches its resistance to denaturation by 8 M urea. The widely different aggregation behavior exhibited by these naturally occurring TTR variants in response to mechanical agitation under close to physiological conditions provides insight into how small sequence differences can contribute to the evolutionary fitness of different animals.

DOI: https://doi.org/10.64898/2026.07.09.737598
bioRxiv. 2026 Jul 23. pii: 2026.07.20.739556. [Epub ahead of print]

Leveraging Supramolecular Polymers to Induce the Targeted Protein Degradation of α-Synuclein.

Windfield S Swetman, Malay Mondal, Ashe M Davis, Vijay Rangachari, Tristan D Clemons.

Halting the progression of neurodegenerative diseases remains one of the foremost challenges in medicinal chemistry due to the complex biology that drives disease progression. For example, a hallmark of synucleinopathies, such as Parkinson's disease, is the misfolding and aggregation of the protein α-Synuclein (α-Syn), driving the formation of toxic oligomers and fibrils that avoid natural intracellular clearance mechanisms, participate in unusual protein-protein interactions, and ultimately contribute to the death of dopaminergic neurons. The field of targeted protein degradation (TPD) has emerged as an innovative therapeutic route to selectively degrade proteins of interest that leverage natural intracellular protein degradation machinery. First generation TPD therapeutics have traditionally been designed as bifunctional, chimeric compounds in which a short covalent linker tethers a ligand designed to bind target proteins to a ligand that initiates an either proteosome- or lysosome-dependent protein degradation cascade. While initial studies have indicated the promise of these approaches, translation to the clinical setting has been challenging due to difficulties in achieving cellular internalization, long-term stability, and establishment of a generalizable strategy. To overcome these obstacles, this work has focused on adding modularity and dynamic capability to this classical model by leveraging a multivalent macromolecular approach to TPD. Specifically, peptide amphiphiles (PAs) were designed to self-assemble into high-aspect-ratio supramolecular nanofibers and present peptide epitopes on the surface of the fibers to target simultaneous binding of α-Syn and recruitment of enzymes that facilitate entry into the lysosome-dependent chaperone-mediated autophagy protein degradation pathway. In vitro application of these bioactive PA nanofibers has demonstrated the ability to independently internalize in cells and reduce α-Syn protein levels selectively and effectively. While further optimization of this model has the potential to be a viable therapeutic against α-Syn aggregation, the modularity of these supramolecular nanofibers through facile monomer design and incorporation illustrates the potential of establishing a platform technology for targeting a diverse range of pathologic proteins.

DOI: https://doi.org/10.64898/2026.07.20.739556
J Mol Liq. 2026 Sep 01. pii: 129765. [Epub ahead of print]457

Aggregation of Amyloid-like Peptides in Different Solvents.

Siwaporn Sungted, Warin Rangubpit, Saree Phongphanphanee, Norio Yoshida, Cristiano L Dias, Jirasak Wong-Ekkabut.

The aggregation of amphipathic peptides into β-sheet rich structures is a hallmark of several neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. At the molecular level, the toxic mechanism of these peptides involves an increase in the permeation of the cellular membrane, which starts with the partition of nonpolar and polar residues at the water-lipid interface that facilitates aggregation. Here, we study this process using all-atom molecular dynamics simulations in four model peptides composed of 4 phenylalanine (F), 2 lysine (K), and 2 glutamic acid (E) under three solvent conditions. In two sequences, nonpolar and charged amino acids alternate along the chain (FKFEFKFE and FFKKFFEE), and, in the other two sequences (FFFKFEKE and FFFFKKEE), they are segregated to the N- and C-terminals. Peptides are solvated in water and octane to study aggregation in hydrophilic and hydrophobic solvents, respectively. In all simulations, peptides aggregate promptly, adopting mostly random coil conformations; except for FKFEFKFE, which spontaneously forms β-sheet conformations in water that resemble the cross-beta structures found in amyloid diseases. Aggregation takes place with a lower free energy of dimerization in octane compared to water. Simulations are also performed in a water-octane to mimic the water-lipid interface where amyloid peptides aggregate before damaging cell membranes. All peptides are spontaneously attracted to this polar-nonpolar interface which corresponds to a minimum in the free energy profile. At the interface, peptides generally exhibit low backbone interaction energies with a high content of secondary structure. The types of secondary structure formed in the system depend on the sequence pattern. In addition, the arrangement of polar and nonpolar residues modulates the free energy profile of peptide transfer from water to octane, and monomers adsorb at the interface more preferentially than the β-sheet dimer. These findings provide insights into how sequence pattern and solvent environment influence peptide aggregation, secondary structure formation, and interfacial behavior.

DOI: https://doi.org/10.1016/j.molliq.2026.129765
Molecules. 2026 Jul 09. pii: 2418. [Epub ahead of print]31(14):

Cholesterol at the Center of Alzheimer's Disease: A Unifying Hypothesis on the Pathogenic Mechanism.

Bao Ting Zhu.

  It is hypothesized that in most cases of sporadic late-onset Alzheimer's disease (LOAD), the abnormally elevated cholesterol level in brain neurons represents a critical causative factor that drives the pathogenic processes of LOAD. Specifically, it is hypothesized that the abnormally elevated neuronal cholesterol will disrupt mitochondrial structure and metabolic activity, resulting in ATP deficiency as well as reduced formation of neuroactive metabolic intermediates (such as mevalonate and geranylgeraniol) along the cholesterol synthesis pathway in brain neurons. In addition, the abnormally elevated neuronal cholesterol will cause direct neuronal damage as well as other pathogenic changes in the brain, including increased formation and deposition of amyloid β (Aβ) plaques. It is speculated that Aβ accumulation and plaque formation in most LOAD cases only represent characteristic secondary pathological changes and are usually not the main force driving the pathogenesis of LOAD. As discussed in detail in this paper, abnormally elevated neuronal cholesterol in conjunction with ATP deficiency and lack of neuroactive metabolic intermediates will not only cause learning and memory impairment, but will also induce tauopathy and reduce the formation of cholinergic vesicles. It is expected that these pathogenic changes are more readily seen initially in ischemia-sensitive neurons in hippocampus and posterior parietal cortex, which are then followed by neurodegenerative and atrophic changes in other brain regions along with progressive cognitive decline. As explained in this paper, ApoE4 is a major risk factor in LOAD because it has a drastically reduced ability than ApoE2 and ApoE3 to efflux excess cholesterol out of neurons. Overall, there is a large body of direct, indirect and circumstantial clinical and experimental evidence which jointly offers strong support for the cholesterol-centered hypothesis on the etiology and pathogenesis of LOAD. Considerable efforts are made to apply the proposed hypothesis to offer a better mechanistic explanation for many of the poorly understood experimental and/or clinical observations related to AD (mostly LOAD).

Keywords:  Alzheimer’s disease; amyloid β; apolipoprotein E; cholesterol; neuronal cholesterol dysregulation; pathogenic mechanism; tauopathy

DOI:  https://doi.org/10.3390/molecules31142418
Adv Pharm Bull. 2026 May;16(1): 119-128

Psoralen and Seselin Stabilize the α-helix Structure in Lysozyme and Inhibit the α-helix to β-sheet Exchange: An Efficient Anti-Amyloidogenic Mechanism.

Parisa Panah-Amand, Leila Sadeghi, Arezu Marefat, Gholamreza Dehghan.

   Purpose: More than thirty human proteins have natural propensity to misfold and amyloid fibril formation that are important in the initiation and development of neurodegenerative disease. Therefore, preventing or reversing amyloid aggregation by using drugs or plant-based small molecules such as coumarin compounds could be useful. This study aimed to investigate the anti-amyloidogenic potential of psoralen and seselin, two types of coumarin compounds, on hen egg white lysozyme (HEWL) as a model system.
Method: ThioflavinT (ThT), Congo red and ANS fluorescence, electron microscopy and circular dichroism were used to fibrillogenesis assay and structural analysis in the presence and absence of the compounds. Interaction of HEWL and coumarins evaluated by using surface plasmon resonance (SPR) and molecular docking and simulation.
Results: The results indicated the ThT and ANS fluorescence intensities decreased in the presence of psoralen and seselin in a dose-dependent dependent manner, suggesting a strong inhibitory effect of compounds on HEWL fibril formation. The results confirmed coumarins could destabilize the pre-formed fibrils. Furthermore, Fluorescence analysis confirmed that coumarin interaction induces conformational changes in HEWL, evidenced by formation of non-fluorescent complexes and altered microenvironments around Tyr and Trp residues. CD spectrum revealed that coumarins can inhibit the α-helix to β-sheet exchange. SPR results showed psoralen could bind to HEWL more tightly.
Conclusion: In agreement with experimental results, the molecular docking studies confirmed the conformational changes of HEWL upon interaction with psoralen and seselin. This study adds to the body of knowledge about rational drug design against the amyloidogenesis process.

Keywords:  Anti-amyloidogenic; Coumarin compounds; Fibril formation; Fibrillation reversion; Hen egg white lysozyme

DOI:  https://doi.org/10.34172/apb.025.40838
Res Sq. 2026 Jul 16. pii: rs.3.rs-9441514. [Epub ahead of print]

Distinctive properties of the prion protein in the brain and retina in the amyloidosis associated with the PRNP F198S Mutation.

Bernardino Ghetti, Bradley S Glazier, Michele Fiorini, Kathy L Newell, José M Bonnin, Jill R Murrell, Leah Rie Varner, Max Jacobsen, James F Striebel, Suzette A Priola, Gianluigi Zanusso.

  Prion protein (PrP) deposits in the form of diffuse and cored plaques occur in most gray matter areas of the brain of individuals affected by Gerstmann-Strässler-Scheinker disease (GSS) associated with the F198S mutation in PRNP; however, the PrP deposits in the retina have not been characterized. Furthermore, a comparative analysis of PrP deposits occurring in the brain and in the retina in GSS has not been carried out. We hypothesize that the PrP aggregation and seeding properties in the brain and retina differ. The aim of this study was to analyze PrP from brains and retinas of individuals affected by GSS, all carriers of the PRNP F198S mutation from the same pedigree. Postmortem tissues from these patients were analyzed using neuropathologic and biochemical methods including Real-Time Quaking Induced Conversion assay. PrP deposits in the retina were found only in the outer plexiform layer, did not have tinctorial property of amyloid and were immunopositive using nine antibodies of epitopes throughout the PrP sequence. The biochemical analysis showed that PrP-F198S in the retina is partially detergent-insoluble, is assembled in large-size aggregates, and has seeding property. In addition, the glycosylation of full-length PrP in the retina was more complex than that of control PrP. Furthermore, the homogenates of retina did not contain the 8 kDa PrP internal fragments (PrPIF) as brain homogenates do; however, a PrPIF was experimentally generated using proteinase K. In conclusion, we report for the first time the neuropathologic and biochemical properties of PrP in the retina of individuals carrying F198S and compare them with those in the brain of the same individuals. The fact that in GSS F198S, PrPIF is constitutive only in the brain points to the need of identifying whether there is a difference in proteolytic mechanisms between the retina and brain.

Keywords:  Gerstmann-Sträussler-Scheinker disease; PRNP F198S mutation; PRNP gene; prion; retina

DOI:  https://doi.org/10.21203/rs.3.rs-9441514/v1
J Mass Spectrom. 2026 Aug;61(8): e70098

Mass Spectrometric Characterization of Native Insulin Hexamers and Non-Native Heptamers: Formation and Stability Across Insulin Analogs.

Emmanuel Dare, Colton G Dixon, Kenneth W Lee.

Insulin aggregation and oligomerization present significant challenges in both therapeutic formulation and fundamental studies of amyloid formation, particularly due to the transient and heterogeneous nature of early-stage oligomers. Here, we employ ion mobility-mass spectrometry (IM-MS) to characterize the oligomeric distributions of human insulin and two clinically relevant analogs, aspart (rapid-acting) and glargine (long-acting), in excipient-containing solutions designed to stabilize native forms of insulin and under aggregation-inducing conditions. Comparison of insulin analogs revealed distinct aggregation propensities that correlate with each analog's therapeutic design. In general, stable zinc-coordinated hexamers formed most readily in the presence of excipients, and various oligomers formed under aggregation-inducing conditions, with a noticeable prevalence of heptamer formation. We further investigated the structure and stability of native hexamers and non-native heptamers using collision-induced dissociation and collision-induced unfolding experiments. Although the expected single-monomer ejection was the main dissociation pathway for both species, zinc-coordinated hexamers also dissociated into two zinc-adducted trimers, whereas heptamers dissociated into dimer/pentamer and trimer/tetramer pairs. Gas-phase unfolding indicated conservation of subunit tertiary structure in hexamers and no distinct folded structures in heptamer subunits. Overall, this work demonstrates the utility of IM-MS as a rapid, high-resolution platform for probing insulin aggregation pathways and evaluating current and future insulin analog formulations.

DOI: https://doi.org/10.1002/jms.70098
Chem Biomed Imaging. 2026 Jul 27. 4(7): 1379-1389

Antiamyloid Antibody Effects on Aβ-42 Protein Aggregates Profiled Using Nanospectroscopy.

Nico Kummer, Martina Cihova, Peter Niraj Nirmalraj.

  Anti-amyloid-β (Aβ) monoclonal antibodies are designed to selectively target protein biomarkers and promote amyloid clearance in Alzheimer's disease. Yet the effects of antibodies on individual Aβ protein aggregates remain to be fully clarified. The work presented here employs nanospectroscopy (atomic force microscopy combined with infrared spectroscopy) to resolve morphological and secondary structural changes in Aβ-42 protein aggregates upon treatment with aducanumab and lecanemab antibodies (biosimilars). The treatment of Aβ-42 peptides with aducanumab resulted in reduction of oligomer prevalence and formation of larger-diameter fibril bundles confirmed from the AFM height maps and infrared spectral readouts recorded at nanometer-scale spatial resolution. Conversely, lecanemab treatment of Aβ-42 peptides did not suppress oligomer generation but was observed to preferentially bind along the full length of the nodular-shaped protofibril surface. Importantly, neither aducanumab nor lecanemab was observed to induce any surface adsorption-driven disassembly of Aβ-42 protofibrils or elongated mature fibrils. Thus, nanospectroscopy enables direct characterization of antibody-amyloid interfacial interactions and provides insights into the distinct modes of action of emerging anti-Aβ therapeutics through label-free chemical imaging.

Keywords:  Alzheimer’s disease; aducanumab; lecanemab; nanospectroscopy; protofibrils

DOI:  https://doi.org/10.1021/cbmi.5c00188
Brain Sci. 2026 Jul 18. pii: 757. [Epub ahead of print]16(7):

Low-Intensity Focused Ultrasound Alters Alzheimer's Disease Pathology, In Vivo, as a Function of Ultrasound Dose and Age.

Alissa Phutirat, Kahte A Culevski, Hannah Mach, Jamie Kwon, Henry Tan, Gabe Koh, Caren Marzban, Pierre D Mourad.

   BACKGROUND/OBJECTIVES: Alzheimer's Disease (AD) and vascular dementia contribute up to ~75% of dementia cases, as determined via autopsy. AD arises in part due to the buildup of aberrant proteins (amyloid beta (Aβ) and Tau); vascular dementia is caused by reduced cerebral blood flow. Each dementia mechanisms damages brain. Bobola et al. found that their low-intensity focused ultrasound (FUS) protocol applied to the brains of the 5XFAD mouse model of AD reduced Aβ by 50% through activation of microglia. Eguchi et al. found that their own FUS protocol applied to the brains of the same mouse model reduced Aβ by 15% and increased cerebral blood flow by 50% through an increase in endothelial nitric oxide synthase (eNOS). Here, we sought to test a combined version of those two FUS protocols, expecting both a decrease in Aβ burden and an increase in eNOS.
METHODS: Using a diagnostic ultrasound probe, we applied our combined FUS protocol primarily to the left hippocampus of anesthetized 5XFAD mice, for an hour a day, for three days for younger mice and for five days for older mice. On day three or five, respectively, we harvested their brains and performed histological analysis to assess Aβ burden, microglial activation and their co-localization with Aβ, as well as the burden of eNOS within neuronal nuclei (here called intra-neuronal eNOS) and outside of neurons.
RESULTS: Relative to untreated mice, the treated younger mice had more activated microglia co-localized with Aβ and reduced Aβ burden for large plaques, as well as no change in each measure of eNOS. In contrast, the treated older AD mice had no change in activated microglia co-localized with Aβ, and no change in Aβ burden. However, relative to untreated older AD mice, FUS decreased total and extra-neuronal eNOS and increased intra-neuronal eNOS.
CONCLUSIONS: The ability of our FUS protocol to reduce Aβ burden and alter the eNOS distribution depends critically upon the age of the AD mice (more Aβ plaques for a comparable number of microglia for older mice relative to younger mice) and duration of the treatment. The observed decrease in extra-neuronal eNOS distribution in older AD mice caused by FUS raises the concern that our protocol may increase ischemia, while the increase in intra-neuronal eNOS may counteract that effect via protection of synaptic function. These findings also identify two candidate therapeutic windows for our FUS treatment protocol, each requiring more research before translation to humans. One window is early intervention to maximize Aβ plaque removal via activation of microglia. The second is later intervention to protect synaptic function if it is possible to mitigate the potential ischemic risk caused by the differential effects of FUS on eNOS.

Keywords:  Alzheimer’s disease; FUS; focused ultrasound; vascular dementia

DOI:  https://doi.org/10.3390/brainsci16070757
bioRxiv. 2026 Jul 22. pii: 2026.07.21.739636. [Epub ahead of print]

Munc18 reprograms the intrinsic neuronal SNARE complex assembly pathway.

Vicky Vishvakarma, Edwin R Chapman.

The SNARE proteins syntaxin/SNAP-25B (t-SNAREs) and synaptobrevin (v-SNARE) contain motifs that assemble into four-helix bundles to drive synaptic vesicle exocytosis; SNAP-25B contributes two helices, D1 and D2. The sequence in which these motifs interact remains unresolved. To address this, we used fluorescence anisotropy of SNARE motifs to conduct real-time order-of-addition experiments and found that the order in which components are mixed can determine whether on- or off-pathway complexes are formed. Beginning with soluble SNARE fragments alone, the first step in assembly is the binding of D1 to syntaxin, followed by the binding of synaptobrevin and D2, where the latter motif acts as a gatekeeper to control v-SNARE•t-SNARE interactions. We then examined the impact of two regulatory factors, Munc18 and the MUN domain of Munc13-1. Strikingly, in the presence of Munc18, all four isolated SNARE motifs must be present at the same time for assembly to occur, revealing a concerted mechanism, while the Munc13-1 fragment was without effect. We created C-SCORE, which reports assembly of the two SNARE motifs of SNAP-25B via FRET, and confirmed that in the presence of Munc18, SNARE assembly becomes concerted. Munc18 also disaggregated syntaxin, potentially contributing to its activation. Finally, our findings regarding SNARE motif folding were well-correlated with function using full-length SNAREs in in vitro lipid mixing assays. Hence, Munc18 acts as a molecular chaperone that directly promotes the concurrent assembly of SNARE proteins into functional fusion machines.

DOI: https://doi.org/10.64898/2026.07.21.739636
Membranes (Basel). 2026 Jul 06. pii: 234. [Epub ahead of print]16(7):

A New Anatomy of Autophagic Clearance: On the Roles of Intrinsic Disorder in the Membrane-Less on Membrane-Encapsulated Mechanism.

Vladimir N Uversky, Hana Popelka, Daniel J Klionsky.

  Autophagy is a carefully regulated catabolic process that utilizes assemblies of specific sets of macromolecules operating at multiple stages of the pathway. Discoveries in recent years show that autophagy markedly relies on liquid-liquid phase separation (LLPS). Here, we present parameters that indicate the plasticity of autophagy proteins and their probability to undergo LLPS in macroautophagy and microautophagy. We show that microautophagy is an extremely LLPS-friendly pathway. Several mechanisms involving proteins in the autophagy machinery that drive LLPS on various types of membranes to regulate this process or that undergo LLPS as autophagic cargo are described in detail. We also summarize the factors that modulate the LLPS potential of autophagy proteins. A high probability of autophagy-related proteins to undergo spontaneous LLPS shown here can direct future research on the role of protein droplets in autophagy.

Keywords:  autophagy; intrinsically disordered protein; intrinsically disordered region; liquid-liquid phase separation; macroautophagy; microautophagy; posttranslational modification; protein1protein interaction

DOI:  https://doi.org/10.3390/membranes16070234
bioRxiv. 2026 Jul 14. pii: 2026.07.10.737840. [Epub ahead of print]

α-Synuclein pathology differentially alters T-type calcium currents in vulnerable and resilient substantia nigra dopaminergic subpopulations.

Megan L Beaver, Pallavi Bommareddy, Natalie Z McLean, Valerie J Lewitus, Kathleen Maguire-Zeiss, Rebekah C Evans.

Aggregation of α-synuclein protein is a characteristic of Parkinson's disease pathology that relates to the degeneration of vulnerable dopaminergic neurons and motor symptoms of the disease. However, α-synuclein pathology can contribute to neuronal dysfunction by disrupting several processes within the cell, including intracellular calcium balance, mitochondrial function, and synaptic function. Here, we use a preformed fibril (PFF) model of synucleinopathy to examine effects of striatal α-synuclein seeding on dopamine neurons of the substantia nigra pars compacta (SNc). The SNc is heterogeneous and contains dopaminergic neurons with differential vulnerability to Parkinson's disease pathology. We found that intrastriatal injections of PFFs differentially affect these SNc neuron subtypes by increasing the excitability of resilient SNc neurons, while altering tonic firing patterns and T-type calcium currents in vulnerable SNc neurons. In addition, we performed comprehensive electrophysiological analyses and neural morphology reconstructions on SNc neurons from PFF and monomer injected mice. These findings provide insights to the selective vulnerability of SNc neuron subtypes and further our understanding of the role of α-synuclein in Parkinson's disease progression and circuit dysfunction.

DOI: https://doi.org/10.64898/2026.07.10.737840
J Parkinsons Dis. 2026 Jul 30. 1877718X261471025

Where does excessive beta in Parkinson's disease originate? Insights from a case of unilateral cortico-pallidal pathway dysfunction.

Leonardo Rigon, Valentina D'Onofrio, Laura Ludovica Grassi, Dario Ciprietti, Andrea Landi, Angelo Antonini, Andrea Guerra.

Plain language summaryDetecting the source of abnormal beta oscillations in Parkinson's Disease: evidence from a case of impaired connection between cerebral cortex and basal ganglia.In Parkinson's Disease, a key feature is an exaggerated, oscillatory activity in the brain called the "beta rhythm", which occurs in the circuit, particularly relevant for motor functions, connecting the cortex (the outer brain layer) and the basal ganglia (the deeper structures). Scientists have long debated whether the exact source of this pathological activity was located in the cortex or in the basal ganglia. This report describes a critical clue from an unexpected event: a person with Parkinson's disease developed temporary swelling (edema) that affected both the sensorimotor cortex and the basal ganglia. Notably, this event was limited to one side of the brain and occurred in a subject who carried a medical device that enables recordings of the beta rhythm from inside the basal ganglia. In this peculiar case, the excessive beta rhythm on the affected side was completely suppressed and only returned once the swelling in the overlying sensorimotor cortex had resolved, even though the edema in the basal ganglia itself had recovered earlier. This unique observation suggests that the integrity of the cortex is essential for the pathological beta rhythm to occur in Parkinson's Disease, lending strong support to the theory that this disruptive electrical rhythm is generated in the cortex before spreading to deeper brain structures such as the basal ganglia.

DOI: https://doi.org/10.1177/1877718X261471025
bioRxiv. 2026 Jul 23. pii: 2026.07.20.738977. [Epub ahead of print]

MicroRNA-223 Enhances Microglia-Dependent Clearance of Amyloid Beta Plaques and Ameliorates Behavioral Deficits in a Mouse Model of Alzheimer's Disease.

Andre Krunic, Nikkitha Umesh Ganesh, Ugur Coskun, William Brennan, Chandani Patel, Ojasi Joshi, Jane Lee, Tori Shiyang Gu, Jaclyn Caruso, Aoife O'Connell, Charles Lisboa, Nicholas Crossland, Margareta Kurkela, Tcw Julia, Abigail Fowler, Tuan Leng Tay, Andre Fischer, Ivana Delalle, Jan K Blusztajn, Tiffany J Mellott.

The Alzheimer's disease (AD) brain is characterized by dysregulated expression of multiple microRNAs (miRNA), positioning them as promising diagnostic and therapeutic targets. The levels of glia-enriched miR-223 are abnormal in the brains and plasma of AD patients and miR-223 is neuroprotective in models of stroke. However, whether miR-223 can be beneficial in AD is not known. Here, we report that intracerebroventricular (ICV) injection of miR-223 oligonucleotide mimic alleviated cognitive impairment, reduced amyloid beta (Aβ) pathology, and ameliorated the defects in synaptic marker expression in App NL-G-F AD model mice. Mechanistically, miR-223 induced microglial clustering around Aβ plaques with a concomitant upregulation of microglial phagocytic receptors AXL, TREM2 and CD11c, while pharmacological microglial depletion abolished the plaque-clearance phenotype. Moreover, in human iPSC-derived microglia miR-223 directly targeted multiple genes in the endo-lysosomal pathway, including AD risk gene SPPL2A , indicating that it acts as a major regulator of microglial phenotype. Lastly, long-term AAV-mediated overexpression of miR-223 recapitulates its beneficial effects on cognition, pathology, and synaptic marker expression. Our study demonstrates a novel approach for the treatment of AD using miR-223 and highlights the potential of RNAi-based therapeutics in neurodegenerative disease.

DOI: https://doi.org/10.64898/2026.07.20.738977
bioRxiv. 2026 Jul 22. pii: 2026.07.17.739026. [Epub ahead of print]

Astrocyte-driven small vessel disease is an early, amyloid-independent feature of PSEN1 E280A familial Alzheimer's disease.

Jessica Lisa Villalba-Moreno, Yassir El-Amri, Keun-Young Kim, Nelson David Villalba-Moreno, Mohsin Shafiq, Carolina Ortiz-Cordero, Shiwei Wang, J Alejandro Ossa, Isaura Suarez-Uribe, Duvan Cardona-Madrigal, Andres Villegas, Markus Glatzel, Susanne Krasemann, Rafael Posada-Duque, Laura L Kiessling, Francisco Lopera, Joseph Arboleda-Velasquez, Rajesh Kalaria, Mark Ellisman, Diego Sepulveda-Falla.

Cerebral Small vessel disease (cSVD) is a prevalent feature of Alzheimer's disease (AD) pathology. Whether this pathology is a late consequence of amyloid and tau accumulation or an early, direct effect of PSEN1 dysfunction has remained unresolved. We found that it is more severe in familial AD (FAD) caused by E280A mutation in presenilin 1 (PSEN1). These cases present with a distinctive proteomic signature, associated with pathological features, more dysregulated in the occipital cortex (OC) compared to the frontal cortex (FC), and characterized by multiple dysregulated proteins involved in extracellular matrix (ECM) and RNA-associated processes. This proteomic fingerprint was associated with abnormal collagen build up, ECM disorganization, and signatures of aberrant angiogenesis. Six months old transgenic knock-in mice homozygous for Psen1 E280A mutation (PSEN1Ki) also showed a similar phenotype with microvascular tortuosity and proteomic changes. Critically, these mice develop neither Aβ plaques nor tau tangles, indicating that the shared microvascular and RNA-associated changes are direct consequences of PSEN1 dysfunction rather than downstream effects of amyloid pathology. Remarkably, dysregulated RNA-associated protein networks overlapped between FAD and PSEN1Ki mice. Cerebral microvessels microstructure in PSEN1Ki mice at two months and six months showed abnormal astrocytic end-feet with lamellar deposits implicating blood-brain barrier damage. Finally, single nuclei transcriptomic analysis of AD patients and controls showed similar abnormal astrocytes in both sporadic and familial variants, but FAD astrocytes expressed dysregulated genes identified in the proteomic analyses, such as GLUL, APOE, and CLU. Our findings suggest that cSVD is an early pathological event in PSEN1 FAD and that is driven by abnormal RNA-associated processes and astrocytic dysfunction.

DOI: https://doi.org/10.64898/2026.07.17.739026
Curr Protein Pept Sci. 2026 Jul 24.

Structural Transitions of β-lactoglobulin Aggregates Observed Under Controlled Heat Treatment.

Miraclin Prasanna A, Priyankar Sen.

   INTRODUCTION: β-Lactoglobulin (β-Lg), the major whey protein in bovine milk, readily undergoes structural transitions leading to amyloid fibril formation under acidic conditions and elevated temperatures. This study investigated the influence of different thermal treatment conditions on the aggregation and fibrillation behavior of β-Lg at pH 2.
METHODS: β-Lg solutions were subjected to three different thermal conditions: stepwise heating from 35o C to 90o C for 12h (Sample A), cyclic heating and cooling from 35o C to 90o C for 24h (Sample B), and constant heating at 90o C for 24h (Sample F). Untreated β-Lg served as the control (Sample M). Structural and morphological changes induced by these treatments were characterized by using intrinsic tryptophan fluorescence spectroscopy, Thioflavin T (ThT) fluorescence assay, circular dichroism (CD) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM).
RESULTS: Spectroscopic and microscopic analyses revealed that stepwise heating (Sample A) promoted amyloid fibril formation, whereas constant heating (Sample F) resulted in extensive aggregation and the development of highly ordered β-sheet-rich fibrillar structures. In contrast, cyclic heating and cooling (Sample B) produced reduced fibril formation, partial retention of native β-Lg structural changes, and distinct aggregate morphologies. Fluorescence, CD, FTIR, and microscopic analyses consistently indicate that Sample F represents the most advanced fibrillar state, while Sample B remained in a partially unfolded and hydrated state with limited changes in the structure.
DISCUSSION: The observed differences in aggregation and fibrillation behavior demonstrated that thermal treatment strongly influences the balance between structural rearrangement and irreversible protein aggregation. Controlled thermal cycling appears to modulate the aggregation pathway by stabilizing intermediate conformational states and limiting the formation of highly ordered amyloid assemblies.
CONCLUSION: The method of heating plays a critical role in determining the structural change of βLg. While prolonged heating promotes extensive fibrillation and aggregation, controlled heatingcooling cycles reduce the extent of amyloid formation and preserve partially native-like structural characteristics. These findings provide valuable insights into the thermal regulation of β-Lg aggregation and may contribute to the development of processing strategies for controlling protein selfassembly in food and biomaterial applications.

Keywords:  amyloid aggregation; dairy processing; protein stability; structural transitions; thermal treatment; β-Lactoglobulin

DOI:  https://doi.org/10.2174/0113892037474248260716172451
Antioxidants (Basel). 2026 Jul 08. pii: 857. [Epub ahead of print]15(7):

Polyphenolic Imidazopyridines as Multifunctional Modulators of Oxidative Stress, Metal Dyshomeostasis, and β1-42 Amyloid Aggregation in an In Vitro Model of Alzheimer's Disease.

Lidia Ciccone, Giovanni Petrarolo, Ilaria D'Agostino, Fabio Scianò, Bianca Laura Bernardoni, Manuela Leri, Jihyae Ann, Susanna Nencetti, Jeewoo Lee, Monica Bucciantini, Concettina La Motta.

  Alzheimer's disease (AD) involves oxidative stress, metal dyshomeostasis, and toxic oligomers of the amyloid-β peptide (Aβ1-42), calling for multifunctional agents. We investigated a panel of imidazo[1,2-a]pyridines bearing catechol or resorcinol motifs previously designed as SIRT1-activating agents. Their antioxidant profile was evaluated using in vitro DPPH and ABTS assays, which revealed promising radical scavenging activities, and TBARS assays on rat brain homogenates showing inhibition of lipid peroxidation, strictly dependent on the phenolic pattern. UV-Vis studies revealed metal-binding properties, particularly Cu2+ and Fe2+ interactions. In Aβ1-42 aggregation assays, the most active derivatives appeared to promote fibril maturation and the growth of large, ThT-low aggregates with distinct morphological features observed by TEM. Notably, Aβ1-42 aggregates generated in the presence of these compounds exhibited reduced cytotoxicity, preserved cell viability, and induced lower ROS levels in RA-differentiated SH-SY5Y cells compared to aggregates formed in their absence. Imaging and FRET analyses further indicated reduced formation of membrane-binding toxic species. Overall, our data suggest that polyphenolic imidazo[1,2-a]pyridines can remodel Aβ1-42 aggregation, redirecting it toward structurally distinct and less toxic assemblies, while also counteracting oxidative and metal-associated damage. These findings highlight their potential as multifunctional agents capable of addressing several pathological hallmarks of AD.

Keywords:  Alzheimer’s disease; Amyloid-β1-42 aggregation; Imidazo[1,2-a]pyridines; metal chelation; oxidative stress; polyphenolic compounds

DOI:  https://doi.org/10.3390/antiox15070857
Transl Neurodegener. 2026 Jul 29. pii: 34. [Epub ahead of print]15(1):

Neuroinflammation in Alzheimer's and Parkinson's diseases: pathogenic mechanisms and therapeutic strategies.

Qin-Qin Wang, Qing-Qing Sun, Yong-Shun Guo, Shu Yin, Jia-Wei Zhou.

  Neuroinflammation is increasingly recognized as a key contributor and amplifier associated with the pathogenesis of Alzheimer's disease (AD) and Parkinson's disease (PD). Neuroinflammation occurs throughout various stages of these diseases with expanding complexity. Currently, no effective therapies exist that specifically target neuroinflammatory processes in these disorders. In this review, we synthesize current understanding of central and peripheral inflammatory mechanisms implicated in both diseases. We illustrate how endogenous pathological triggers, such as amyloid-β (Aβ) peptide, hyperphosphorylated tau, and α-synuclein, activate glial cells, contributing to chronic neuroinflammation that exacerbates neurodegeneration. Additionally, peripheral factors, including systemic inflammation, environmental exposures, and gut-brain axis interactions, are discussed for their roles in modulating neuroinflammatory responses. Notably, the underappreciated roles of oligodendrocyte precursor cells and oligodendrocytes in neuroimmune crosstalk are also highlighted. Advanced methodologies, including glial cell imaging, single-cell transcriptomics, and human induced pluripotent stem cell-derived organoid models, are providing unprecedented insights into the molecular and cellular mechanisms underlying neuroinflammation. Finally, we evaluate emerging therapeutic strategies and ongoing clinical trials targeting neuroinflammatory pathways and analyze the potential of immunomodulatory approaches to slow disease progression. This comprehensive review emphasizes that precise targeting of neuroinflammation represents a tractable strategy for developing effective disease‑modifying treatments for AD and PD.

Keywords:  Advanced methodologies; Alzheimer’s disease; Glial cells; Neuroinflammation; Parkinson’s disease; Therapeutic strategies

DOI:  https://doi.org/10.1186/s40035-026-00571-3