scholarly journals Mechanism of amyloid protein aggregation and the role of inhibitors

2019 ◽  
Vol 91 (2) ◽  
pp. 211-229 ◽  
Author(s):  
Sara Linse
Keyword(s):  
Total Concentration ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Aggregation Process ◽  
Secondary Nucleation ◽  
Toxic Species ◽  
Primary Nucleation ◽  
Effective Inhibition ◽  
Aβ Aggregation

Abstract Inhibition of amyloid β peptide (Aβ) aggregation is an important goal due to the connection of this process with Alzheimer’s disease. Traditionally, inhibitors were developed with an aim to retard the overall macroscopic aggregation. However, recent advances imply that approaches based on mechanistic insights may be more powerful. In such approaches, the microscopic steps underlying the aggregation process are identified, and it is established which of these step(s) lead to neurotoxicity. Inhibitors are then derived to specifically target steps involved in toxicity. The Aβ aggregation process is composed of at minimum three microscopic steps: primary nucleation of monomers only, secondary nucleation of monomers on fibril surface, and elongation of fibrils by monomer addition. The vast majority of toxic species are generated from the secondary nucleation process: this may be a key process to inhibit in order to limit toxicity. Inhibition of primary nucleation, which delays the emergence of toxic species without affecting their total concentration, may also be effective. Inhibition of elongation may instead increase the toxicity over time. Here we briefly review findings regarding secondary nucleation of Aβ, its dominance over primary nucleation, and attempts to derive inhibitors that specifically target secondary nucleation with an aim to limit toxicity.

Dementia-related Bri2 BRICHOS is a versatile molecular chaperone that efficiently inhibits Aβ42 toxicity in Drosophila

2016 ◽  
Vol 473 (20) ◽  
pp. 3683-3704 ◽  
Author(s):  
Helen Poska ◽  
Martin Haslbeck ◽  
Firoz Roshan Kurudenkandy ◽  
Erik Hermansson ◽  
Gefei Chen ◽  
...  
Keyword(s):  
Hippocampal Slices ◽  
Amyloid Β ◽  
Mushroom Bodies ◽  
Amyloid Β Peptide ◽  
Specific Expression ◽  
Efficient Inhibitor ◽  
Transgenic Expression ◽  
Aβ Aggregation

Formation of fibrils of the amyloid-β peptide (Aβ) is suggested to play a central role in neurodegeneration in Alzheimer's disease (AD), for which no effective treatment exists. The BRICHOS domain is a part of several disease-related proproteins, the most studied ones being Bri2 associated with familial dementia and prosurfactant protein C (proSP-C) associated with lung amyloid. BRICHOS from proSP-C has been found to be an efficient inhibitor of Aβ aggregation and toxicity, but its lung-specific expression makes it unsuited to target in AD. Bri2 is expressed in the brain, affects processing of Aβ precursor protein, and increased levels of Bri2 are found in AD brain, but the specific role of its BRICHOS domain has not been studied in vivo. Here, we find that transgenic expression of the Bri2 BRICHOS domain in the Drosophila central nervous system (CNS) or eyes efficiently inhibits Aβ42 toxicity. In the presence of Bri2 BRICHOS, Aβ42 is diffusely distributed throughout the mushroom bodies, a brain region involved in learning and memory, whereas Aβ42 expressed alone or together with proSP-C BRICHOS forms punctuate deposits outside the mushroom bodies. Recombinant Bri2 BRICHOS domain efficiently prevents Aβ42-induced reduction in γ-oscillations in hippocampal slices. Finally, Bri2 BRICHOS inhibits several steps in the Aβ42 fibrillation pathway and prevents aggregation of heat-denatured proteins, indicating that it is a more versatile chaperone than proSP-C BRICHOS. These findings suggest that Bri2 BRICHOS can be a physiologically relevant chaperone for Aβ in the CNS and needs to be further investigated for its potential in AD treatment.

scholarly journals Aggregation Mechanism of Alzheimer’s Amyloid β-Peptide Mediated by α-Strand/α-Sheet Structure

2020 ◽  
Vol 21 (3) ◽  
pp. 1094 ◽  
Author(s):  
Anand Balupuri ◽  
Kwang-Eun Choi ◽  
Nam Sook Kang
Keyword(s):  
Neuronal Damage ◽  
Experimental Studies ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Aggregation Mechanism ◽  
Toxic Species ◽  
Sheet Structure ◽  
Aβ Aggregation ◽  
Dynamics Simulations ◽  
Structural Insights

Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases and a widespread form of dementia. Aggregated forms of the amyloid β-peptide (Aβ) are identified as a toxic species responsible for neuronal damage in AD. Extensive research has been conducted to reveal the aggregation mechanism of Aβ. However, the structure of pathological aggregates and the mechanism of aggregation are not well understood. Recently, experimental studies have confirmed that the α-sheet structure in Aβ drives aggregation and toxicity in AD. However, how the α-sheet structure is formed in Aβ and how it contributes to Aβ aggregation remains elusive. In the present study, molecular dynamics simulations suggest that Aβ adopts the α-strand conformation by peptide-plane flipping. Multiple α-strands interact through hydrogen bonding to form α-sheets. This structure acts as a nucleus that initiates and promotes aggregation and fibrillation of Aβ. Our findings are supported by previous experimental as well as theoretical studies. This study provides valuable structural insights for the design of anti-AD drugs exploiting the α-strand/α-sheet structure.

scholarly journals Autocatalytic amplification of Alzheimer-associated Aβ42 peptide aggregation in human cerebrospinal fluid

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Rebecca Frankel ◽  
Mattias Törnquist ◽  
Georg Meisl ◽  
Oskar Hansson ◽  
Ulf Andreasson ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Amyloid Β ◽  
Peptide Aggregation ◽  
Secondary Nucleation ◽  
Aggregation Mechanism ◽  
Primary Nucleation ◽  
Aβ Aggregation ◽  
Aβ42 Peptide ◽  
The Brain

Abstract Alzheimer’s disease is linked to amyloid β (Aβ) peptide aggregation in the brain, and a detailed understanding of the molecular mechanism of Aβ aggregation may lead to improved diagnostics and therapeutics. While previous studies have been performed in pure buffer, we approach the mechanism in vivo using cerebrospinal fluid (CSF). We investigated the aggregation mechanism of Aβ42 in human CSF through kinetic experiments at several Aβ42 monomer concentrations (0.8–10 µM). The data were subjected to global kinetic analysis and found consistent with an aggregation mechanism involving secondary nucleation of monomers on the fibril surface. A mechanism only including primary nucleation was ruled out. We find that the aggregation process is composed of the same microscopic steps in CSF as in pure buffer, but the rate constant of secondary nucleation is decreased. Most importantly, the autocatalytic amplification of aggregate number through catalysis on the fibril surface is prevalent also in CSF.

scholarly journals Somatostatin binds to the human amyloid β peptide and favors the formation of distinct oligomers

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Hansen Wang ◽  
Lisa D Muiznieks ◽  
Punam Ghosh ◽  
Declan Williams ◽  
Michael Solarski ◽  
...  
Keyword(s):  
Amyloid Β ◽  
Systematic Investigation ◽  
Brain Extract ◽  
Amyloid Β Peptide ◽  
Nanoparticle Tracking Analysis ◽  
Quantitative Mass Spectrometry ◽  
Binding Interface ◽  
Aβ Aggregation ◽  
Somatostatin 14

The amyloid β peptide (Aβ) is a key player in the etiology of Alzheimer disease (AD), yet a systematic investigation of its molecular interactions has not been reported. Here we identified by quantitative mass spectrometry proteins in human brain extract that bind to oligomeric Aβ1-42 (oAβ1-42) and/or monomeric Aβ1-42 (mAβ1-42) baits. Remarkably, the cyclic neuroendocrine peptide somatostatin-14 (SST14) was observed to be the most selectively enriched oAβ1-42 binder. The binding interface comprises a central tryptophan within SST14 and the N-terminus of Aβ1-42. The presence of SST14 inhibited Aβ aggregation and masked the ability of several antibodies to detect Aβ. Notably, Aβ1-42, but not Aβ1-40, formed in the presence of SST14 oligomeric assemblies of 50 to 60 kDa that were visualized by gel electrophoresis, nanoparticle tracking analysis and electron microscopy. These findings may be relevant for Aβ-directed diagnostics and may signify a role of SST14 in the etiology of AD.

scholarly journals Astrocytes and neuroinflammation in Alzheimer's disease

2014 ◽  
Vol 42 (5) ◽  
pp. 1321-1325 ◽  
Author(s):  
Emma C. Phillips ◽  
Cara L. Croft ◽  
Ksenia Kurbatskaya ◽  
Michael J. O’Neill ◽  
Michael L. Hutton ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Inflammatory Responses ◽  
Amyloid Β ◽  
Synaptic Dysfunction ◽  
Amyloid Β Peptide ◽  
Substantial Evidence ◽  
Models Of Disease ◽  
Opposing Effects

Increased production of amyloid β-peptide (Aβ) and altered processing of tau in Alzheimer's disease (AD) are associated with synaptic dysfunction, neuronal death and cognitive and behavioural deficits. Neuroinflammation is also a prominent feature of AD brain and considerable evidence indicates that inflammatory events play a significant role in modulating the progression of AD. The role of microglia in AD inflammation has long been acknowledged. Substantial evidence now demonstrates that astrocyte-mediated inflammatory responses also influence pathology development, synapse health and neurodegeneration in AD. Several anti-inflammatory therapies targeting astrocytes show significant benefit in models of disease, particularly with respect to tau-associated neurodegeneration. However, the effectiveness of these approaches is complex, since modulating inflammatory pathways often has opposing effects on the development of tau and amyloid pathology, and is dependent on the precise phenotype and activities of astrocytes in different cellular environments. An increased understanding of interactions between astrocytes and neurons under different conditions is required for the development of safe and effective astrocyte-based therapies for AD and related neurodegenerative diseases.

scholarly journals Nano-assembly of amyloid β peptide: role of the hairpin fold

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Sibaprasad Maity ◽  
Mohtadin Hashemi ◽  
Yuri L. Lyubchenko
Keyword(s):  
Amyloid Β ◽  
Amyloid Β Peptide

Echinacoside ameliorates the memory impairment and cholinergic deficit induced by amyloid beta peptides via the inhibition of amyloid deposition and toxicology

2017 ◽  
Vol 8 (6) ◽  
pp. 2283-2294 ◽  
Author(s):  
Young-Ji Shiao ◽  
Muh-Hwan Su ◽  
Hang-Ching Lin ◽  
Chi-Rei Wu
Keyword(s):  
Amyloid Beta ◽  
Memory Impairment ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Protective Effects ◽  
Neuronal Function ◽  
Amyloid Beta Peptides ◽  
Beta Peptides ◽  
Amyloid Cascade

This study investigates the role of the amyloid cascade and central neuronal function on the protective effects of echinacoside in amyloid β peptide 1-42 (Aβ 1-42)-treated SH-SY5Y cells and an Aβ 1-42-infused rat.

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