Cryo-EM structures of amyloid-β 42 filaments from human brains

Science ◽  
2022 ◽  
Vol 375 (6577) ◽  
pp. 167-172
Author(s):  
Yang Yang ◽  
Diana Arseni ◽  
Wenjuan Zhang ◽  
Melissa Huang ◽  
Sofia Lövestam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Animal Models ◽  
Human Brain ◽  
Amyloid Β ◽  
Aβ Peptides ◽  
Cryo Electron Microscopy ◽  
Specificity And Sensitivity ◽  
Human Brains ◽  
The Brain

Hi-res view of human Aβ42 filaments Alzheimer’s disease is characterized by a loss of memory and other cognitive functions and the filamentous assembly of Aβ and tau in the brain. The assembly of Aβ peptides into filaments that end at residue 42 is a central event. Yang et al . used electron cryo–electron microscopy to determine the structures of Aβ42 filaments from human brain (see the Perspective by Willem and Fändrich). They identified two types of related S-shaped filaments, each consisting of two identical protofilaments. These structures will inform the development of better in vitro and animal models, inhibitors of Aβ42 assembly, and imaging agents with increased specificity and sensitivity. —SMH

scholarly journals P-Glycoprotein and Breast Cancer Resistance Protein Restrict Apical-to-Basolateral Permeability of Human Brain Endothelium to Amyloid-β

2009 ◽  
Vol 29 (6) ◽  
pp. 1079-1083 ◽  
Author(s):  
Leon M Tai ◽  
A Jane Loughlin ◽  
David K Male ◽  
Ignacio A Romero
Keyword(s):  
Breast Cancer ◽  
Human Brain ◽  
Breast Cancer Resistance Protein ◽  
Amyloid Β ◽  
Cancer Resistance ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Resistance Protein ◽  
The Brain

The clearance of amyloid beta (Aβ) from the brain represents a novel therapeutic target for Alzheimer's disease. Conflicting data exist regarding the contribution of adenosine triphosphatebinding cassette transporters to the clearance of Aβ through the blood-brain barrier. Therefore, we investigated whether Aβ could be a substrate for P-glycoprotein (P-gp) and/or for breast cancer resistance protein (BCRP) using a human brain endothelial cell line, hCMEC/D3. Inhibition of P-gp and BCRP increased apical-to-basolateral, but not basolateral-to-apical, permeability of hCMEC/D3 cells to 125l Aβ 1–40. Our in vitro data suggest that P-gp and BCRP might act to prevent the blood-borne Aβ 1–40 from entering the brain.

scholarly journals Fluorescent indolizine derivative YI-13 detects amyloid-β monomers, dimers, and plaques in the brain of 5XFAD Alzheimer transgenic mouse model

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243041
Author(s):  
DaWon Kim ◽  
Jeong Hwa Lee ◽  
Hye Yun Kim ◽  
Jisu Shin ◽  
Kyeonghwan Kim ◽  
...  
Keyword(s):  
Mouse Model ◽  
Transgenic Mouse ◽  
Neurodegenerative Disorder ◽  
Amyloid Β ◽  
Transgenic Mouse Model ◽  
Aβ Oligomers ◽  
Aβ Peptides ◽  
Soluble Aβ Oligomers ◽  
The Brain

Alzheimer disease (AD) is a neurodegenerative disorder characterized by the aberrant production and accumulation of amyloid-β (Aβ) peptides in the brain. Accumulated Aβ in soluble oligomer and insoluble plaque forms are considered to be a pathological culprit and biomarker of the disorder. Here, we report a fluorescent universal Aβ-indicator YI-13, 5-(4-fluorobenzoyl)-7,8-dihydropyrrolo[1,2-b]isoquinolin-9(6H)-one, which detects Aβ monomers, dimers, and plaques. We synthesized a library of 26 fluorescence chemicals with the indolizine core and screen them through a series of in vitro tests utilizing Aβ as a target and YI-13 was selected as the final imaging candidate. YI-13 was found to stain and visualize insoluble Aβ plaques in the brain tissue, of a transgenic mouse model with five familial AD mutations (5XFAD), by a histochemical approach and to label soluble Aβ oligomers within brain lysates of the mouse model under a fluorescence plate reader. Among oligomers aggregated from monomers and synthetic dimers from chemically conjugated monomers, YI-13 preferred the dimeric Aβ.

scholarly journals Modulation of β-Amyloid Fibril Formation in Alzheimer’s Disease by Microglia and Infection

2020 ◽  
Vol 13 ◽  
Author(s):  
Madeleine R. Brown ◽  
Sheena E. Radford ◽  
Eric W. Hewitt
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Fibril ◽  
Amyloid Β ◽  
Aβ Peptides ◽  
Aβ Amyloid ◽  
Aβ Fibrils ◽  
The Brain

Amyloid plaques are a pathological hallmark of Alzheimer’s disease. The major component of these plaques are highly ordered amyloid fibrils formed by amyloid-β (Aβ) peptides. However, whilst Aβ amyloid fibril assembly has been subjected to detailed and extensive analysis in vitro, these studies may not reproduce how Aβ fibrils assemble in the brain. This is because the brain represents a highly complex and dynamic environment, and in Alzheimer’s disease multiple cofactors may affect the assembly of Aβ fibrils. Moreover, in vivo amyloid plaque formation will reflect the balance between the assembly of Aβ fibrils and their degradation. This review explores the roles of microglia as cofactors in Aβ aggregation and in the clearance of amyloid deposits. In addition, we discuss how infection may be an additional cofactor in Aβ fibril assembly by virtue of the antimicrobial properties of Aβ peptides. Crucially, by understanding the roles of microglia and infection in Aβ amyloid fibril assembly it may be possible to identify new therapeutic targets for Alzheimer’s disease.

scholarly journals Amyloid Beta Peptides and Th1 Cytokines Modulate Human Brain Vascular Smooth Muscle Tonic Contractile Capacity In Vitro: Relevance to Alzheimer’s Disease?

2021 ◽  
Vol 28 (1) ◽  
pp. 64-75
Author(s):  
J. Winny Yun ◽  
Caretia Washington ◽  
Joi McCormick ◽  
Emily Stevenson ◽  
J. Steven Alexander
Keyword(s):  
Blood Flow ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Human Brain ◽  
Inflammatory Cytokines ◽  
Vascular Smooth Muscle Cells ◽  
Cerebral Autoregulation ◽  
Aβ Peptides ◽  
The Brain

Alzheimer’s Disease (AD) is a neurodegenerative condition characterized both by the presence of tau protein neurofibrillary tangles and amyloid beta (Aβ) containing extracellular “plaques”. The cleavage of amyloid precursor protein (APP) yields several Aβ peptides. Although Aβ toxicity to neurons has been described extensively, its effects on other components of the neurovasculature such as vascular smooth muscle cells have been less well characterized. AD is now also recognized as a neurovascular disease characterized by cerebral microbleeds and disturbances in autoregulation. AD is also a neuroinflammatory condition in which several proinflammatory cytokines are elevated and may contribute to the intensification of AD severity. Cerebral autoregulation (the mechanism by which brain blood flow is maintained despite changes in perfusion pressure) is extremely tightly controlled in the brain and shows disturbances in AD. The failure of autoregulation in AD may make the brain susceptible to cerebral microbleeds through a reduced capacity to limit blood flow when pressure is increased. Conversely, reduced vasodilation during low flow might could also exacerbate tissue hypoxia. Currently, whether and how Aβ peptides and inflammatory cytokines depress brain smooth muscle cell tonic contraction is not known, but could reveal important targets in the preservation of autoregulation which is disturbed in AD. We used a collagen gel contractility assay to evaluate the influence of Aβ 25-35, Aβ 1-40 and Aβ 1-42 peptides and inflammatory cytokines on the tonic contractility of human brain vascular smooth muscle cells (HBVSMC) as an in vitro model of cerebral autoregulation. We found that 5 and 10 μM Aβ1-42 significantly depressed HBVSM contractility, while Aβ1-40 5–20 μM had no effect on contractility. Conversely, Aβ25-35 (1–50 μM) increased contractility. Interestingly, the inflammatory cytokines TNF-α (20 ng/mL), IL-1β (20 ng/mL) and IFN- (1000 U/mL) also depressed HBVSM tonic contractility alone and in combination. These data suggest that both the inflammatory milieu in AD as well as the abundance of Aβ peptides may promote autoregulatory failure and increase brain susceptibility to dysregulated perfusion and microbleeds which are an important and devastating characteristic of AD.

scholarly journals If Human Brain Organoids Are the Answer to Understanding Dementia, What Are the Questions?

2020 ◽  
Vol 26 (5-6) ◽  
pp. 438-454 ◽  
Author(s):  
Lezanne Ooi ◽  
Mirella Dottori ◽  
Anthony L. Cook ◽  
Martin Engel ◽  
Vini Gautam ◽  
...  
Keyword(s):  
Cell Culture ◽  
Stem Cell ◽  
Animal Models ◽  
Human Brain ◽  
Ethical Issues ◽  
The Other ◽  
Cell Culture Systems ◽  
The Brain ◽  
In Vitro Modelling

Because our beliefs regarding our individuality, autonomy, and personhood are intimately bound up with our brains, there is a public fascination with cerebral organoids, the “mini-brain,” the “brain in a dish”. At the same time, the ethical issues around organoids are only now being explored. What are the prospects of using human cerebral organoids to better understand, treat, or prevent dementia? Will human organoids represent an improvement on the current, less-than-satisfactory, animal models? When considering these questions, two major issues arise. One is the general challenge associated with using any stem cell–generated preparation for in vitro modelling (challenges amplified when using organoids compared with simpler cell culture systems). The other relates to complexities associated with defining and understanding what we mean by the term “dementia.” We discuss 10 puzzles, issues, and stumbling blocks to watch for in the quest to model “dementia in a dish.”

scholarly journals Is There a Brain Microbiome?

2021 ◽  
Vol 16 ◽  
pp. 263310552110187
Author(s):  
Christopher D Link
Keyword(s):  
Animal Models ◽  
Human Brain ◽  
Neurodegenerative Diseases ◽  
Ground Truth ◽  
Healthy Human ◽  
Strong Motivation ◽  
The Many ◽  
The Brain

Numerous studies have identified microbial sequences or epitopes in pathological and non-pathological human brain samples. It has not been resolved if these observations are artifactual, or truly represent population of the brain by microbes. Given the tempting speculation that resident microbes could play a role in the many neuropsychiatric and neurodegenerative diseases that currently lack clear etiologies, there is a strong motivation to determine the “ground truth” of microbial existence in living brains. Here I argue that the evidence for the presence of microbes in diseased brains is quite strong, but a compelling demonstration of resident microbes in the healthy human brain remains to be done. Dedicated animal models studies may be required to determine if there is indeed a “brain microbiome.”

scholarly journals Human Islet Amyloid Polypeptide Fibril Binding to Catalase: A Transmission Electron Microscopy and Microplate Study

2010 ◽  
Vol 10 ◽  
pp. 879-893 ◽  
Author(s):  
Nathaniel G. N. Milton ◽  
J. Robin Harris
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Islet Amyloid Polypeptide ◽  
Amyloid Β ◽  
Human Islet ◽  
Islet Amyloid ◽  
Human Islet Amyloid Polypeptide ◽  
Transmission Electron

The diabetes-associated human islet amyloid polypeptide (IAPP) is a 37-amino-acid peptide that forms fibrilsin vitroandin vivo. Human IAPP fibrils are toxic in a similar manner to Alzheimer's amyloid-β (Aβ) and prion protein (PrP) fibrils. Previous studies have shown that catalase binds to Aβ fibrils and appears to recognize a region containing the Gly-Ala-Ile-Ile sequence that is similar to the Gly-Ala-Ile-Leu sequence found in human IAPP residues 24-27. This study presents a transmission electron microscopy (TEM)—based analysis of fibril formation and the binding of human erythrocyte catalase to IAPP fibrils. The results show that human IAPP 1-37, 8-37, and 20-29 peptides form fibrils with diverse and polymorphic structures. All three forms of IAPP bound catalase, and complexes of IAPP 1-37 or 8-37 with catalase were identified by immunoassay. The binding of biotinylated IAPP to catalase was high affinity with a KDof 0.77nM, and could be inhibited by either human or rat IAPP 1-37 and 8-37 forms. Fibrils formed by the PrP 118-135 peptide with a Gly-Ala-Val-Val sequence also bound catalase. These results suggest that catalase recognizes a Gly-Ala-Ile-Leu—like sequence in amyloid fibril-forming peptides. For IAPP 1-37 and 8-37, the catalase binding was primarily directed towards fibrillar rather than ribbon-like structures, suggesting differences in the accessibility of the human IAPP 24-27 Gly-Ala-Ile-Leu region. This suggests that catalase may be able to discriminate between different structural forms of IAPP fibrils. The ability of catalase to bind IAPP, Aβ, and PrP fibrils demonstrates the presence of similar accessible structural motifs that may be targets for antiamyloid therapeutic development.

scholarly journals Complex Activity and Short-term Memories in Reciprocally Connected Cerebral Organoids

2021 ◽  
Author(s):  
Tatsuya Osaki ◽  
Yoshiho Ikeuchi
Keyword(s):  
Human Brain ◽  
Three Dimensional ◽  
Oscillatory Activity ◽  
Cellular Functions ◽  
Complex Activity ◽  
Axonal Connections ◽  
Brain Organoid ◽  
External Stimuli ◽  
The Brain

AbstractMacroscopic axonal connections in the human brain distribute information and neuronal activity across the brain. Although this complexity previously hindered elucidation of functional connectivity mechanisms, brain organoid technologies have recently provided novel avenues to investigate human brain function by constructing small segments of the brain in vitro. Here, we describe the neural activity of human cerebral organoids reciprocally connected by a bundle of axons. Compared to conventional organoids, connected organoids produced significantly more intense and complex oscillatory activity. Optogenetic manipulations revealed that the connected organoids could re-play and recapitulate over time temporal patterns found in external stimuli, indicating that the connected organoids were able to form and retain temporal memories. Our findings suggest that connected organoids may serve as powerful tools for investigating the roles of macroscopic circuits in the human brain – allowing researchers to dissect cellular functions in three-dimensional in vitro nervous system models in unprecedented ways.

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