scholarly journals Characterization of amyloid β fibril formation under microgravity conditions

2020 ◽  
Author(s):  
Maho Yagi-Utsumi ◽  
Saeko Yanaka ◽  
Chihong Song ◽  
Tadashi Satoh ◽  
Chiaki Yamazaki ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Protein Crystallization ◽  
Space Station ◽  
Amyloid Β ◽  
Fibril Formation ◽  
Formation Mechanisms ◽  
Amyloid Formation ◽  
Functional Roles ◽  
Solution Condition ◽  
Microgravity Conditions

AbstractAmyloid fibrils are self-assembled and ordered proteinaceous supramolecules structurally characterized by the cross-β spine. Amyloid formation is known to be related to various diseases typified by neurogenerative disorders and involved in a variety of functional roles. Whereas common mechanisms for amyloid formation have been postulated across diverse systems, the mesoscopic morphology of the fibrils is significantly affected by the type of solution condition in which it grows. Amyloid formation is also thought to share a phenomenological similarity with protein crystallization. While many studies have demonstrated the effect of gravity on protein crystallization, its effect on amyloid formation has not been reported. In this study, we conducted an experiment at the International Space Station (ISS) to characterize fibril formation of 40-residue amyloid β (Aβ(1-40)) under microgravity conditions. Our comparative analyses revealed that the Aβ(1-40) fibrilization progresses much more slowly on the ISS than on the ground, similarly to protein crystallization. Furthermore, microgravity promoted the formation of distinct morphologies of Aβ(1-40) fibrils. Our findings demonstrate that the ISS provides an ideal experimental environment for detailed investigations of amyloid formation mechanisms by eliminating the conventionally uncontrollable factors derived from gravity.

scholarly journals Zinc as chaperone-mimicking agent for retardation of amyloid β peptide fibril formation

2015 ◽  
Vol 112 (17) ◽  
pp. 5407-5412 ◽  
Author(s):  
Axel Abelein ◽  
Astrid Gräslund ◽  
Jens Danielsson
Keyword(s):  
Amyloid Fibrils ◽  
Profile Analysis ◽  
Amyloid Β ◽  
Nmr Relaxation ◽  
Fibril Formation ◽  
Relaxation Dispersion ◽  
Amyloid Β Peptide ◽  
Amyloid Formation ◽  
Aggregation Process ◽  
N Terminus

Metal ions have emerged to play a key role in the aggregation process of amyloid β (Aβ) peptide that is closely related to the pathogenesis of Alzheimer’s disease. A detailed understanding of the underlying mechanistic process of peptide–metal interactions, however, has been challenging to obtain. By applying a combination of NMR relaxation dispersion and fluorescence kinetics methods we have investigated quantitatively the thermodynamic Aβ–Zn2+ binding features as well as how Zn2+ modulates the nucleation mechanism of the aggregation process. Our results show that, under near-physiological conditions, substoichiometric amounts of Zn2+ effectively retard the generation of amyloid fibrils. A global kinetic profile analysis reveals that in the absence of zinc Aβ40 aggregation is driven by a monomer-dependent secondary nucleation process in addition to fibril-end elongation. In the presence of Zn2+, the elongation rate is reduced, resulting in reduction of the aggregation rate, but not a complete inhibition of amyloid formation. We show that Zn2+ transiently binds to residues in the N terminus of the monomeric peptide. A thermodynamic analysis supports a model where the N terminus is folded around the Zn2+ ion, forming a marginally stable, short-lived folded Aβ40 species. This conformation is highly dynamic and only a few percent of the peptide molecules adopt this structure at any given time point. Our findings suggest that the folded Aβ40–Zn2+ complex modulates the fibril ends, where elongation takes place, which efficiently retards fibril formation. In this conceptual framework we propose that zinc adopts the role of a minimal antiaggregation chaperone for Aβ40.

scholarly journals Fibrillogenesis in Alzheimer's disease of amyloid β peptides and apolipoprotein E

1995 ◽  
Vol 306 (2) ◽  
pp. 599-604 ◽  
Author(s):  
E M Castano ◽  
F Prelli ◽  
T Wisniewski ◽  
A Golabek ◽  
R A Kumar ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Apolipoprotein E ◽  
Late Onset ◽  
Senile Plaques ◽  
Amyloid Β ◽  
Fibril Formation ◽  
Tau Proteins ◽  
Amyloid Formation

A central event in Alzheimer's disease is the conformational change from normally circulating soluble amyloid beta peptides (A beta) and tau proteins into amyloid fibrils, in the form of senile plaques and neurofibrillary tangles respectively. The apolipoprotein E (apoE) gene locus has recently been associated with late-onset Alzheimer's disease. It is not know whether apoE plays a direct role in the pathogenesis of the disease. In the present work we have investigated whether apoE can affect the known spontaneous in vitro formation of amyloid-like fibrils by synthetic A beta analogues using a thioflavine-T assay for fibril formation, electron microscopy and Congo Red staining. Our results show that, under the conditions used, apoE directly promotes amyloid fibril formation, increasing both the rate of fibrillogenesis and the total amount of amyloid formed. ApoE accelerated fibril formation of both wild-type A beta-(1-40) and A beta-(1-40A), an analogue created by the replacement of valine with alanine at residue 18, which alone produces few amyloid-like fibrils. However, apoE produced only a minimal effect on A beta-(1-40Q), found in the Dutch variant of Alzheimer's disease. When recombinant apoE isoforms were used, apoE4 was more efficient than apoE3 at enhancing amyloid formation. These in vitro observations support the hypothesis that apoE acts as a pathological chaperone, promoting the beta-pleated-sheet conformation of soluble A beta into amyloid fibres, and provide a possible explanation for the association of the apoE4 genetic isoform with Alzheimer's disease.

scholarly journals Identification of Novel 1,3,5-Triphenylbenzene Derivative Compounds as Inhibitors of Hen Lysozyme Amyloid Fibril Formation

2019 ◽  
Vol 20 (22) ◽  
pp. 5558
Author(s):  
Hassan Ramshini ◽  
Reza Tayebee ◽  
Alessandra Bigi ◽  
Francesco Bemporad ◽  
Cristina Cecchi ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Amyloid Fibril ◽  
Inhibitory Effect ◽  
Fibril Formation ◽  
Amyloid Formation ◽  
Binding Assays ◽  
Egg White Lysozyme ◽  
Amyloid Fibril Formation ◽  
Activity Measurements ◽  
Model Protein

Deposition of soluble proteins as insoluble amyloid fibrils is associated with a number of pathological states. There is a growing interest in the identification of small molecules that can prevent proteins from undergoing amyloid fibril formation. In the present study, a series of small aromatic compounds with different substitutions of 1,3,5-triphenylbenzene have been synthesized and their possible effects on amyloid fibril formation by hen egg white lysozyme (HEWL), a model protein for amyloid formation, and of their resulting toxicity were examined. The inhibitory effect of the compounds against HEWL amyloid formation was analyzed using thioflavin T and Congo red binding assays, atomic force microscopy, Fourier-transform infrared spectroscopy, and cytotoxicity assays, such as the 3-(4,5-Dimethylthiazol)-2,5-Diphenyltetrazolium Bromide (MTT) reduction assay and caspase-3 activity measurements. We found that all compounds in our screen were efficient inhibitors of HEWL fibril formation and their associated toxicity. We showed that electron-withdrawing substituents such as –F and –NO2 potentiated the inhibitory potential of 1,3,5-triphenylbenzene, whereas electron-donating groups such as –OH, –OCH3, and –CH3 lowered it. These results may ultimately find applications in the development of potential inhibitors against amyloid fibril formation and its biologically adverse effects.

Sensing and modulation of amyloid fibrils by photo-switchable organic dots

Nanoscale ◽  
2020 ◽  
Vol 12 (32) ◽  
pp. 16805-16818
Author(s):  
Aslam Uddin ◽  
Bibhisan Roy ◽  
Gregor P. Jose ◽  
Sk Saddam Hossain ◽  
Partha Hazra
Keyword(s):  
Amyloid Fibrils ◽  
Amyloid Fibril ◽  
Early Stage ◽  
Fibril Formation ◽  
Amyloid Formation ◽  
Amyloid Fibril Formation

Our study demonstrates that organic dots can be used for the imaging and early stage detection of amyloid fibril formation and the modulation of amyloid formation pathways.

scholarly journals Characterization of amyloid β fibril formation under microgravity conditions

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Maho Yagi-Utsumi ◽  
Saeko Yanaka ◽  
Chihong Song ◽  
Tadashi Satoh ◽  
Chiaki Yamazaki ◽  
...  
Keyword(s):  
Amyloid Β ◽  
Fibril Formation ◽  
Microgravity Conditions

scholarly journals Kinetic Transition in Amyloid Assembly as a Screening Assay for Oligomer-Selective Dyes

Biomolecules ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 539 ◽  
Author(s):  
Jeremy Barton ◽  
D. Sebastian Arias ◽  
Chamani Niyangoda ◽  
Gustavo Borjas ◽  
Nathan Le ◽  
...  
Keyword(s):  
Crystal Violet ◽  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Fibril Formation ◽  
Thioflavin T ◽  
Screening Assay ◽  
Kinetic Transition ◽  
Amyloid Assembly

Assembly of amyloid fibrils and small globular oligomers is associated with a significant number of human disorders that include Alzheimer’s disease, senile systemic amyloidosis, and type II diabetes. Recent findings implicate small amyloid oligomers as the dominant aggregate species mediating the toxic effects in these disorders. However, validation of this hypothesis has been hampered by the dearth of experimental techniques to detect, quantify, and discriminate oligomeric intermediates from late-stage fibrils, in vitro and in vivo. We have shown that the onset of significant oligomer formation is associated with a transition in thioflavin T kinetics from sigmoidal to biphasic kinetics. Here we showed that this transition can be exploited for screening fluorophores for preferential responses to oligomer over fibril formation. This assay identified crystal violet as a strongly selective oligomer-indicator dye for lysozyme. Simultaneous recordings of amyloid kinetics with thioflavin T and crystal violet enabled us to separate the combined signals into their underlying oligomeric and fibrillar components. We provided further evidence that this screening assay could be extended to amyloid-β peptides under physiological conditions. Identification of oligomer-selective dyes not only holds the promise of biomedical applications but provides new approaches for unraveling the mechanisms underlying oligomer versus fibril formation in amyloid assembly.

scholarly journals Seminal Plasma Accelerates Semen-derived Enhancer of Viral Infection (SEVI) Fibril Formation by the Prostatic Acid Phosphatase (PAP248–286) Peptide

2012 ◽  
Vol 287 (15) ◽  
pp. 11842-11849 ◽  
Author(s):  
Joanna S. Olsen ◽  
John T. M. DiMaio ◽  
Todd M. Doran ◽  
Caitlin Brown ◽  
Bradley L. Nilsson ◽  
...  
Keyword(s):  
Acid Phosphatase ◽  
Viral Infection ◽  
Seminal Plasma ◽  
Amyloid Fibrils ◽  
Divalent Cations ◽  
Prostatic Acid Phosphatase ◽  
Fibril Formation ◽  
Amyloid Formation ◽  
Precursor Peptide

Amyloid fibrils contained in semen, known as SEVI, or semen-derived enhancer of viral infection, have been shown to increase the infectivity of HIV dramatically. However, previous work with these fibrils has suggested that extensive time and nonphysiologic levels of agitation are necessary to induce amyloid formation from the precursor peptide (a proteolytic cleavage product of prostatic acid phosphatase, PAP248–286). Here, we show that fibril formation by PAP248–286is accelerated dramatically in the presence of seminal plasma (SP) and that agitation is not required for fibrillization in this setting. Analysis of the effects of specific SP components on fibril formation by PAP248–286revealed that this effect is primarily due to the anionic buffer components of SP (notably inorganic phosphate and sodium bicarbonate). Divalent cations present in SP had little effect on the kinetics of fibril formation, but physiologic levels of Zn2+strongly protected SEVI fibrils from degradation by seminal proteases. Taken together, these data suggest that in thein vivoenvironment, PAP248–286is likely to form fibrils efficiently, thus providing an explanation for the presence of SEVI in human semen.

scholarly journals Designing transthyretin mutants affecting tetrameric structure: implications in amyloidogenicity

2000 ◽  
Vol 348 (1) ◽  
pp. 167-172 ◽  
Author(s):  
Clara REDONDO ◽  
Ana M. DAMAS ◽  
Maria João M. SARAIVA
Keyword(s):  
Molecular Mechanisms ◽  
Amyloid Fibrils ◽  
Hydrophobic Interactions ◽  
Fibril Formation ◽  
Amyloid Formation ◽  
Structural Determinants ◽  
Tetrameric Structure ◽  
Structural Subunit ◽  
The Stability

The molecular mechanisms that convert soluble transthyretin (TTR) tetramers into insoluble amyloid fibrils are still unknown; dissociation of the TTR tetramer is a pre-requisite for amyloid formation in vitro and involvement of monomers and/or dimers in fibril formation has been suggested by structural studies. We have designed four mutated proteins with the purpose of stabilizing [Ser117 → Cys (S117C) and Glu92 → Cys (E92C)] or destabilizing [Asp18 → Asn (D18N) and Leu110 → Ala (D110A)] the dimer/tetramer interactions in TTR, aiming at elucidating structural determinants in amyloidogenesis. The resistance of the mutated proteins to dissociation was analysed by HPLC studies of diluted TTR preparations. Both ‘stabilized’ mutants migrated as tetramers and, upon dilution, no other TTR species was observed, confirming the increased resistance to dissociation. For the ‘destabilized’ mutants, a mixture of tetrameric and monomeric forms co-existed at low dilution and the latter increased upon 10-fold dilution. Both of the destabilizing mutants formed amyloid in vitro when acidified. This result indicated that both the AB loop of TTR, destabilized in D18N, and the hydrophobic interactions affecting the dimer-dimer interfaces in L110A are implicated in the stability of the tetrameric structure. The stabilized mutants, which were dimeric in nature through disulphide bonding, were unable to polymerize into amyloid, even at pH 3.2. When the amyloid formation assay was repeated in the presence of 2-mercaptoethanol, upon disruption of the S-S bridges of these stable dimers, amyloid fibril formation was observed. This experimental evidence suggests that monomers, rather than dimers, are the repeating structural subunit comprising the amyloid fibrils.

scholarly journals The Aggregation Conditions Define Whether EGCG is an Inhibitor or Enhancer of α-Synuclein Amyloid Fibril Formation

2020 ◽  
Vol 21 (6) ◽  
pp. 1995 ◽  
Author(s):  
Rebecca Sternke-Hoffmann ◽  
Alessia Peduzzo ◽  
Najoua Bolakhrif ◽  
Rainer Haas ◽  
Alexander K. Buell
Keyword(s):  
Amyloid Fibrils ◽  
Amyloid Fibril ◽  
Epigallocatechin Gallate ◽  
Small Region ◽  
Fibril Formation ◽  
Oxidation Products ◽  
Relevant Parameter ◽  
Amyloid Formation ◽  
Experimental Conditions ◽  
Amyloid Fibril Formation

The amyloid fibril formation by α -synuclein is a hallmark of various neurodegenerative disorders, most notably Parkinson’s disease. Epigallocatechin gallate (EGCG) has been reported to be an efficient inhibitor of amyloid formation by numerous proteins, among them α -synuclein. Here, we show that this applies only to a small region of the relevant parameter space, in particular to solution conditions where EGCG readily oxidizes, and we find that the oxidation product is a much more potent inhibitor compared to the unmodified EGCG. In addition to its inhibitory effects, EGCG and its oxidation products can under some conditions even accelerate α -synuclein amyloid fibril formation through facilitating its heterogeneous primary nucleation. Furthermore, we show through quantitative seeding experiments that, contrary to previous reports, EGCG is not able to re-model α -synuclein amyloid fibrils into seeding-incompetent structures. Taken together, our results paint a complex picture of EGCG as a compound that can under some conditions inhibit the amyloid fibril formation of α -synuclein, but the inhibitory action is not robust against various physiologically relevant changes in experimental conditions. Our results are important for the development of strategies to identify and characterize promising amyloid inhibitors.

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