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1.
Mol Cell ; 82(5): 933-949.e9, 2022 03 03.
Article in English | MEDLINE | ID: mdl-35120587

ABSTRACT

BAX and BAK are key apoptosis regulators that mediate the decisive step of mitochondrial outer membrane permeabilization. However, the mechanism by which they assemble the apoptotic pore remains obscure. Here, we report that BAX and BAK present distinct oligomerization properties, with BAK organizing into smaller structures with faster kinetics than BAX. BAK recruits and accelerates BAX assembly into oligomers that continue to grow during apoptosis. As a result, BAX and BAK regulate each other as they co-assemble into the same apoptotic pores, which we visualize. The relative availability of BAX and BAK molecules thereby determines the growth rate of the apoptotic pore and the relative kinetics by which mitochondrial contents, most notably mtDNA, are released. This feature of BAX and BAK results in distinct activation kinetics of the cGAS/STING pathway with implications for mtDNA-mediated paracrine inflammatory signaling.


Subject(s)
DNA, Mitochondrial , Mitochondria , bcl-2 Homologous Antagonist-Killer Protein/metabolism , bcl-2-Associated X Protein/metabolism , Animals , Apoptosis/genetics , Cell Line, Tumor , DNA, Mitochondrial/genetics , DNA, Mitochondrial/metabolism , Humans , Inflammation/genetics , Inflammation/metabolism , Mitochondria/genetics , Mitochondria/metabolism , Protein Multimerization , bcl-2 Homologous Antagonist-Killer Protein/genetics , bcl-2-Associated X Protein/genetics
2.
EMBO J ; 43(19): 4274-4297, 2024 Oct.
Article in English | MEDLINE | ID: mdl-39143238

ABSTRACT

Gasdermin D (GSDMD) executes the cell death program of pyroptosis by assembling into oligomers that permeabilize the plasma membrane. Here, by single-molecule imaging, we elucidate the yet unclear mechanism of Gasdermin D pore assembly and the role of cysteine residues in GSDMD oligomerization. We show that GSDMD preassembles at the membrane into dimeric and trimeric building blocks that can either be inserted into the membrane, or further assemble into higher-order oligomers prior to insertion into the membrane. The GSDMD residues Cys39, Cys57, and Cys192 are the only relevant cysteines involved in GSDMD oligomerization. S-palmitoylation of Cys192, combined with the presence of negatively-charged lipids, controls GSDMD membrane targeting. Simultaneous Cys39/57/192-to-alanine (Ala) mutations, but not Ala mutations of Cys192 or the Cys39/57 pair individually, completely abolish GSDMD insertion into artificial membranes as well as into the plasma membrane. Finally, either Cys192 or the Cys39/Cys57 pair are sufficient to enable formation of GSDMD dimers/trimers, but they are all required for functional higher-order oligomer formation. Overall, our study unveils a cooperative role of Cys192 palmitoylation-mediated membrane binding and Cys39/57/192-mediated oligomerization in GSDMD pore assembly. This study supports a model in which Gasdermin D oligomerization relies on a two-step mechanism mediated by specific cysteine residues.


Subject(s)
Cell Membrane , Cysteine , Lipoylation , Phosphate-Binding Proteins , Phosphate-Binding Proteins/metabolism , Phosphate-Binding Proteins/genetics , Cysteine/metabolism , Humans , Cell Membrane/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Intracellular Signaling Peptides and Proteins/genetics , Protein Multimerization , HEK293 Cells , Animals , Gasdermins
3.
PLoS Biol ; 22(7): e3002727, 2024 Jul.
Article in English | MEDLINE | ID: mdl-39042667

ABSTRACT

Reduction of amyloid beta (Aß) has been shown to be effective in treating Alzheimer's disease (AD), but the underlying assumption that neurons are the main source of pathogenic Aß is untested. Here, we challenge this prevailing belief by demonstrating that oligodendrocytes are an important source of Aß in the human brain and play a key role in promoting abnormal neuronal hyperactivity in an AD knock-in mouse model. We show that selectively suppressing oligodendrocyte Aß production improves AD brain pathology and restores neuronal function in the mouse model in vivo. Our findings suggest that targeting oligodendrocyte Aß production could be a promising therapeutic strategy for treating AD.


Subject(s)
Alzheimer Disease , Amyloid beta-Peptides , Disease Models, Animal , Mice, Transgenic , Neurons , Oligodendroglia , Animals , Female , Humans , Male , Mice , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Alzheimer Disease/genetics , Amyloid beta-Peptides/metabolism , Brain/metabolism , Brain/pathology , Gene Knock-In Techniques , Neurons/metabolism , Oligodendroglia/metabolism
4.
Mol Psychiatry ; 29(2): 369-386, 2024 02.
Article in English | MEDLINE | ID: mdl-38102482

ABSTRACT

Understanding the role of small, soluble aggregates of beta-amyloid (Aß) and tau in Alzheimer's disease (AD) is of great importance for the rational design of preventative therapies. Here we report a set of methods for the detection, quantification, and characterisation of soluble aggregates in conditioned media of cerebral organoids derived from human iPSCs with trisomy 21, thus containing an extra copy of the amyloid precursor protein (APP) gene. We detected soluble beta-amyloid (Aß) and tau aggregates secreted by cerebral organoids from both control and the isogenic trisomy 21 (T21) genotype. We developed a novel method to normalise measurements to the number of live neurons within organoid-conditioned media based on glucose consumption. Thus normalised, T21 organoids produced 2.5-fold more Aß aggregates with a higher proportion of larger (300-2000 nm2) and more fibrillary-shaped aggregates than controls, along with 1.3-fold more soluble phosphorylated tau (pTau) aggregates, increased inflammasome ASC-specks, and a higher level of oxidative stress inducing thioredoxin-interacting protein (TXNIP). Importantly, all this was detectable prior to the appearance of histological amyloid plaques or intraneuronal tau-pathology in organoid slices, demonstrating the feasibility to model the initial pathogenic mechanisms for AD in-vitro using cells from live genetically pre-disposed donors before the onset of clinical disease. Then, using different iPSC clones generated from the same donor at different times in two independent experiments, we tested the reproducibility of findings in organoids. While there were differences in rates of disease progression between the experiments, the disease mechanisms were conserved. Overall, our results show that it is possible to non-invasively follow the development of pathology in organoid models of AD over time, by monitoring changes in the aggregates and proteins in the conditioned media, and open possibilities to study the time-course of the key pathogenic processes taking place.


Subject(s)
Alzheimer Disease , Amyloid beta-Peptides , Down Syndrome , Induced Pluripotent Stem Cells , Organoids , tau Proteins , Humans , Organoids/metabolism , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Alzheimer Disease/genetics , tau Proteins/metabolism , Down Syndrome/metabolism , Down Syndrome/genetics , Down Syndrome/pathology , Induced Pluripotent Stem Cells/metabolism , Amyloid beta-Peptides/metabolism , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/metabolism , Neurons/metabolism , Brain/metabolism , Brain/pathology , Carrier Proteins/metabolism , Carrier Proteins/genetics , Trisomy/genetics , Oxidative Stress , Plaque, Amyloid/metabolism , Plaque, Amyloid/pathology , Culture Media, Conditioned , Microscopy, Fluorescence/methods
5.
Br J Clin Psychol ; 63(2): 197-212, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38214135

ABSTRACT

OBJECTIVES: Assessment of autism-related behaviours (ARBs) in children has generally been limited to direct observations in clinical settings or informant-based reports. The widespread availability of video-streaming devices has made home observations of children's ARBs feasible. This approach could enable assessment of the generalization and durability of interventions and may be able to overcome methodological limitations of predominant current assessment approaches (response biases, limited sensitivity to treatment). DESIGN AND METHODS: Forty-four autistic children and their families participated in a repeated-measures study with a correlational design. Approximately 10 hr of unprompted behaviour at home were videorecorded over the course of a week (2 hr per day) for each participant. Gold standard measures of ARBs were also administered (ADOS-2 and ADI-R). Two home-based observational measures of ARBs utilizing streaming video were developed and evaluated: the ARCHER and the CHEERS. Trained independent evaluators made ratings on the ARCHER, CHEERS and an observational measure of parental responsiveness. RESULTS: Correlations with the ADOS-2 and ADI-R were .47 and .34 for ARCHER scores and .51 and .48 for CHEERS scores, respectively. In linear mixed models, more responsive parenting was associated with fewer ARBs on a daily basis. Children spent their afternoons engaged in many typical activities including electronics, homework and games with family members, and ARBs were more prominent in some of these contexts (e.g., electronics) than others (e.g., family games). CONCLUSIONS: Home-based observational assessment of ARBs may be useful for clinical and descriptive research.


Subject(s)
Psychometrics , Video Recording , Humans , Male , Female , Child , Psychometrics/instrumentation , Child, Preschool , Parent-Child Relations , Autistic Disorder/psychology , Parents/psychology , Child Behavior/psychology , Parenting/psychology , Autism Spectrum Disorder/psychology , Behavior Observation Techniques/methods
6.
Angew Chem Int Ed Engl ; 63(21): e202317756, 2024 05 21.
Article in English | MEDLINE | ID: mdl-38523073

ABSTRACT

Hyperphosphorylation and aggregation of the protein tau play key roles in the development of Alzheimer's disease (AD). While the molecular structure of the filamentous tau aggregates has been determined to atomic resolution, there is far less information available about the smaller, soluble aggregates, which are believed to be more toxic. Traditional techniques are limited to bulk measures and struggle to identify individual aggregates in complex biological samples. To address this, we developed a novel single-molecule pull-down-based assay (MAPTau) to detect and characterize individual tau aggregates in AD and control post-mortem brain and biofluids. Using MAPTau, we report the quantity, as well as the size and circularity of tau aggregates measured using super-resolution microscopy, revealing AD-specific differences in tau aggregate morphology. By adapting MAPTau to detect multiple phosphorylation markers in individual aggregates using two-color coincidence detection, we derived compositional profiles of the individual aggregates. We find an AD-specific phosphorylation profile of tau aggregates with more than 80 % containing multiple phosphorylations, compared to 5 % in age-matched non-AD controls. Our results show that MAPTau is able to identify disease-specific subpopulations of tau aggregates phosphorylated at different sites, that are invisible to other methods and enable the study of disease mechanisms and diagnosis.


Subject(s)
Alzheimer Disease , Protein Aggregates , tau Proteins , Humans , Alzheimer Disease/metabolism , Alzheimer Disease/diagnosis , tau Proteins/metabolism , tau Proteins/chemistry , tau Proteins/analysis , Phosphorylation , Single Molecule Imaging/methods , Brain/metabolism , Brain/diagnostic imaging , Brain/pathology
7.
J Phys Chem A ; 127(15): 3490-3496, 2023 Apr 20.
Article in English | MEDLINE | ID: mdl-37023388

ABSTRACT

Single molecule fluorescence microscopy has the unique advantage to provide real-time information on the spatiotemporal assembly of individual protein complexes in cellular membranes. This includes the assembly of proteins into oligomer species of numerous copy numbers. However, there is a need for improved tracing analysis of the real-time growth kinetics of these assemblies in cells with single molecule resolution. Here, we present an automated analysis software to accurately measure the real-time kinetics of assembly of individual high-order oligomer complexes. Our software comes with a simple Graphical User Interface (GUI), is available as a source code and an executable, and can analyze a full data set of several hundred to thousand molecules in less than 2 minutes. Importantly, this software is suitable for the analysis of intracellular protein oligomers, whose stoichiometry is usually more difficult to quantify due to variability in signal detection in the different areas of the cell. We validated our method with simulated ground-truth data and time-lapse images of diffraction-limited oligomeric assemblies of BAX and BAK proteins on mitochondria of cells undergoing apoptosis. Our approach provides the broad community of biologists with a fast, user-friendly tool to trace the compositional evolution of macromolecular assemblies, and potentially model their growth for a deeper understanding of the structural and biophysical mechanisms underlying their functions.


Subject(s)
Software , Kinetics
8.
Nat Methods ; 16(8): 711-714, 2019 08.
Article in English | MEDLINE | ID: mdl-31263253

ABSTRACT

Super-resolution microscopy allows imaging of cellular structures with high throughput and detail. However, the efficient and quantitative analysis of images generated is challenging with existing tools. Here, we develop ASAP (automated structures analysis program) to enable rapid and automated detection, classification and quantification of super-resolved structures. We validate ASAP on ground truth data and demonstrate its broad applicability by analyzing images of nucleoporins, TORC1 complexes, endocytic vesicles and Bax pores.


Subject(s)
Endosomes/metabolism , Mechanistic Target of Rapamycin Complex 1/analysis , Microscopy, Fluorescence/methods , Molecular Imaging/methods , Nuclear Pore Complex Proteins/analysis , Transport Vesicles/metabolism , bcl-2-Associated X Protein/analysis , Humans
9.
Bioinformatics ; 37(21): 3998-4000, 2021 11 05.
Article in English | MEDLINE | ID: mdl-33964131

ABSTRACT

MOTIVATION: Imaging single molecules has emerged as a powerful characterization tool in the biological sciences. The detection of these under various noise conditions requires the use of algorithms that are dependent on the end-user inputting several parameters, the choice of which can be challenging and subjective. RESULTS: In this work, we propose DeepSinse, an easily trainable and useable deep neural network that can detect single molecules with little human input and across a wide range of signal-to-noise ratios. We validate the neural network on the detection of single bursts in simulated and experimental data and compare its performance with the best-in-class, domain-specific algorithms. AVAILABILITYAND IMPLEMENTATION: Ground truth ROI simulating code, neural network training, validation code, classification code, ROI picker, GUI for simulating, training and validating DeepSinse as well as pre-trained networks are all released under the MIT License on www.github.com/jdanial/DeepSinse. The dSTORM dataset processing code is released under the MIT License on www.github.com/jdanial/StormProcessor. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.


Subject(s)
Biological Science Disciplines , Deep Learning , Humans , Neural Networks, Computer , Algorithms , Signal-To-Noise Ratio
10.
Neurobiol Dis ; 153: 105327, 2021 06.
Article in English | MEDLINE | ID: mdl-33705938

ABSTRACT

The aggregation of misfolded proteins is a fundamental pathology in neurodegeneration which remains poorly understood due to its exceptional complexity and lack of appropriate characterization tools that can probe the role of the low concentrations of heterogeneous protein aggregates formed during the progression of the disease. In this review, we explain the principles underlying the operation of single molecule microscopy, an imaging method that can resolve molecules one-by-one, its application to imaging and characterizing individual protein aggregates in human samples and in vitro as well as the important questions in neurobiology this has answered and can answer.


Subject(s)
Dementia/pathology , Neurodegenerative Diseases/pathology , Protein Aggregation, Pathological/pathology , Single Molecule Imaging/methods , Humans , In Vitro Techniques , Protein Aggregates
11.
Proc Natl Acad Sci U S A ; 112(40): 12299-303, 2015 Oct 06.
Article in English | MEDLINE | ID: mdl-26401022

ABSTRACT

Lipid rafts are submicron proteolipid domains thought to be responsible for membrane trafficking and signaling. Their small size and transient nature put an understanding of their dynamics beyond the reach of existing techniques, leading to much contention as to their exact role. Here, we exploit the differences in light scattering from lipid bilayer phases to achieve dynamic imaging of nanoscopic lipid domains without any labels. Using phase-separated droplet interface bilayers we resolve the diffusion of domains as small as 50 nm in radius and observe nanodomain formation, destruction, and dynamic coalescence with a domain lifetime of 220±60 ms. Domain dynamics on this timescale suggests an important role in modulating membrane protein function.


Subject(s)
Lipid Bilayers/chemistry , Membrane Lipids/chemistry , Membrane Microdomains/chemistry , Nanostructures/chemistry , Diffusion , Kinetics , Light , Microscopy, Interference/methods , Nanotechnology/methods , Scattering, Radiation , Solubility , Surface Properties , Temperature
12.
Soft Matter ; 13(9): 1788-1793, 2017 03 01.
Article in English | MEDLINE | ID: mdl-28165095

ABSTRACT

Changes in local lipid composition are thought to play a key role in regulating many complex cellular processes. By studying lipid organization in artificial lipid bilayers the physical principles underlying these process can be studied in detail. However, such in vitro measurements are often hindered by heterogeneities in the lipid composition of individual bilayers prepared by current bulk methods. Here, the lipid composition of an individual droplet interface bilayer is varied by lipid titration into the bilayer from the oil phase in a microfluidic device. Control of lipid composition allows the reversible switching between single- and two-phase regions and sampling of specific lipid compositions in an individual bilayer. This method enables controlled modulation of composition-sensitive processes in a single lipid membrane.

13.
Soft Matter ; 13(13): 2550, 2017 03 29.
Article in English | MEDLINE | ID: mdl-28317973

ABSTRACT

Correction for 'On demand modulation of lipid composition in an individual bilayer' by John S. H. Danial et al., Soft Matter, 2017, 13, 1788-1793.

14.
Nat Commun ; 15(1): 4695, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38824138

ABSTRACT

Which isoforms of apolipoprotein E (apoE) we inherit determine our risk of developing late-onset Alzheimer's Disease (AD), but the mechanism underlying this link is poorly understood. In particular, the relevance of direct interactions between apoE and amyloid-ß (Aß) remains controversial. Here, single-molecule imaging shows that all isoforms of apoE associate with Aß in the early stages of aggregation and then fall away as fibrillation happens. ApoE-Aß co-aggregates account for ~50% of the mass of diffusible Aß aggregates detected in the frontal cortices of homozygotes with the higher-risk APOE4 gene. We show how dynamic interactions between apoE and Aß tune disease-related functions of Aß aggregates throughout the course of aggregation. Our results connect inherited APOE genotype with the risk of developing AD by demonstrating how, in an isoform- and lipidation-specific way, apoE modulates the aggregation, clearance and toxicity of Aß. Selectively removing non-lipidated apoE4-Aß co-aggregates enhances clearance of toxic Aß by glial cells, and reduces secretion of inflammatory markers and membrane damage, demonstrating a clear path to AD therapeutics.


Subject(s)
Alzheimer Disease , Amyloid beta-Peptides , Apolipoprotein E4 , Apolipoproteins E , Alzheimer Disease/metabolism , Alzheimer Disease/genetics , Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Humans , Apolipoproteins E/metabolism , Apolipoproteins E/genetics , Animals , Apolipoprotein E4/metabolism , Apolipoprotein E4/genetics , Protein Isoforms/metabolism , Protein Isoforms/genetics , Mice , Female , Protein Aggregates , Male , Protein Aggregation, Pathological/metabolism , Mice, Transgenic , Neuroglia/metabolism
15.
Cell Rep Methods ; 3(6): 100499, 2023 06 26.
Article in English | MEDLINE | ID: mdl-37426747

ABSTRACT

We developed the aggregate characterization toolkit (ACT), a fully automated computational suite based on existing and widely used core algorithms to measure the number, size, and permeabilizing activity of recombinant and human-derived aggregates imaged with diffraction-limited and super-resolution microscopy methods at high throughput. We have validated ACT on simulated ground-truth images of aggregates mimicking those from diffraction-limited and super-resolution microscopies and showcased its use in characterizing protein aggregates from Alzheimer's disease. ACT is developed for high-throughput batch processing of images collected from multiple samples and is available as an open-source code. Given its accuracy, speed, and accessibility, ACT is expected to be a fundamental tool in studying human and non-human amyloid intermediates, developing early disease stage diagnostics, and screening for antibodies that bind toxic and heterogeneous human amyloid aggregates.


Subject(s)
Alzheimer Disease , Protein Aggregates , Humans , Alzheimer Disease/diagnosis , Amyloid , Amyloidogenic Proteins , Algorithms
16.
Nat Protoc ; 17(11): 2570-2619, 2022 11.
Article in English | MEDLINE | ID: mdl-36002768

ABSTRACT

Single-molecule localization microscopy (SMLM) leverages the power of modern optics to unleash ultra-precise structural nanoscopy of complex biological machines in their native environments as well as ultra-sensitive and high-throughput medical diagnostics with the sensitivity of a single molecule. To achieve this remarkable speed and resolution, SMLM setups are either built by research laboratories with strong expertise in optical engineering or commercially sold at a hefty price tag. The inaccessibility of SMLM to life scientists for technical or financial reasons is detrimental to the progress of biological and biomedical discoveries reliant on super-resolution imaging. In this work, we present the NanoPro, an economic, high-throughput, high-quality and easy-to-assemble SMLM for super-resolution imaging. We show that our instrument performs similarly to the most expensive, best-in-class commercial microscopes and rivals existing open-source microscopes at a lower price and construction complexity. To facilitate its wide adoption, we compiled a step-by-step protocol, accompanied by extensive illustrations, to aid inexperienced researchers in constructing the NanoPro as well as assessing its performance by imaging ground-truth samples as small as 20 nm. The detailed visual instructions make it possible for students with little expertise in microscopy engineering to construct, validate and use the NanoPro in <1 week, provided that all components are available.


Subject(s)
Microscopy , Single Molecule Imaging , Humans , Single Molecule Imaging/methods
17.
Biophys Rep (N Y) ; 2(1): None, 2022 Mar 09.
Article in English | MEDLINE | ID: mdl-35299715

ABSTRACT

Super-resolution microscopy allows complex biological assemblies to be observed with remarkable resolution. However, the presence of uneven Gaussian-shaped illumination hinders its use in quantitative imaging or high-throughput assays. Methods developed to circumvent this problem are often expensive, hard to implement, or not applicable to total internal reflection fluorescence imaging. We herein demonstrate a cost-effective method to overcome these challenges using a small square-core multimodal optical fiber as the coupler. We characterize our method with synthetic, recombinant, and cellular systems imaged under total internal reflection fluorescence and highly inclined and laminated optical sheet illuminations to demonstrate its ability to produce highly uniform images under all conditions.

18.
J Phys Chem Lett ; 13(3): 822-829, 2022 Jan 27.
Article in English | MEDLINE | ID: mdl-35044771

ABSTRACT

Analysis of single-molecule brightness allows subunit counting of high-order oligomeric biomolecular complexes. Although the theory behind the method has been extensively assessed, systematic analysis of the experimental conditions required to accurately quantify the stoichiometry of biological complexes remains challenging. In this work, we develop a high-throughput, automated computational pipeline for single-molecule brightness analysis that requires minimal human input. We use this strategy to systematically quantify the accuracy of counting under a wide range of experimental conditions in simulated ground-truth data and then validate its use on experimentally obtained data. Our approach defines a set of conditions under which subunit counting by brightness analysis is designed to work optimally and helps in establishing the experimental limits in quantifying the number of subunits in a complex of interest. Finally, we combine these features into a powerful, yet simple, software that can be easily used for the analysis of the stoichiometry of such complexes.


Subject(s)
Single Molecule Imaging
19.
ACS Nano ; 15(8): 13591-13603, 2021 Aug 24.
Article in English | MEDLINE | ID: mdl-34347438

ABSTRACT

Hexagonal boron nitride (hBN) is a promising host material for room-temperature, tunable solid-state quantum emitters. A key technological challenge is deterministic and scalable spatial emitter localization, both laterally and vertically, while maintaining the full advantages of the 2D nature of the material. Here, we demonstrate emitter localization in hBN in all three dimensions via a monolayer (ML) engineering approach. We establish pretreatment processes for hBN MLs to either fully suppress or activate emission, thereby enabling such differently treated MLs to be used as select building blocks to achieve vertical (z) emitter localization at the atomic layer level. We show that emitter bleaching of ML hBN can be suppressed by sandwiching between two protecting hBN MLs, and that such thin stacks retain opportunities for external control of emission. We exploit this to achieve lateral (x-y) emitter localization via the addition of a patterned graphene mask that quenches fluorescence. Such complete emitter site localization is highly versatile, compatible with planar, scalable processing, allowing tailored approaches to addressable emitter array designs for advanced characterization, monolithic device integration, and photonic circuits.

20.
Brain Commun ; 3(3): fcab147, 2021.
Article in English | MEDLINE | ID: mdl-34396107

ABSTRACT

Protein aggregation likely plays a key role in the initiation and spreading of Alzheimer's disease pathology through the brain. Soluble aggregates of amyloid beta are believed to play a key role in this process. However, the aggregates present in humans are still poorly characterized due to a lack of suitable methods required for characterizing the low concentration of heterogeneous aggregates present. We have used a variety of biophysical methods to characterize the aggregates present in human Alzheimer's disease brains at Braak stage III. We find soluble amyloid beta-containing aggregates in all regions of the brain up to 200 nm in length, capable of causing an inflammatory response. Rather than aggregates spreading through the brain as disease progresses, it appears that aggregation occurs all over the brain and that different brain regions are at earlier or later stages of the same process, with the later stages causing increased inflammation.

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