scholarly journals Aß40 displays amyloidogenic properties in the non-transgenic mouse brain but does not exacerbate Aß42 toxicity in Drosophila.

2020 ◽  
Author(s):  
Lorena de Mena ◽  
Michael A Smith ◽  
Jason Martin ◽  
Katie L Dunton ◽  
Carolina Ceballos-Diaz ◽  
...  
Keyword(s):  
Mouse Brain ◽  
Self Assembly ◽  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Model Systems ◽  
Amyloid Angiopathy ◽  
Amyloid Deposits ◽  
Amyloid Aggregates ◽  
Amyloid Cascade

Abstract Background Self-assembly of the amyloid-β (Aβ) peptide into aggregates, from small oligomers to amyloid fibrils, is fundamentally linked with Alzheimer’s disease (AD). However it is clear that not all forms of Aβ are equally harmful, and that linking a specific aggregate to toxicity also depends on the assays and model systems used [1, 2]. Though a central postulate of the amyloid cascade hypothesis, there remain many gaps in our understanding regarding the links between Aβ deposition and neurodegeneration. Methods In this study, we examined familial mutations of Aβ that increase aggregation and oligomerization, E22G and DE22, and induce cerebral amyloid angiopathy, E22Q and D23N. We also investigated synthetic mutations that stabilize dimerization, S26C, and a phospho-mimetic, S8E, and non-phospho-mimetic, S8A. To that end, we utilized BRI2-Aβ fusion technology and rAAV2/1 based somatic brain transgenesis in mice to selectively express individual mutant Aβ species in vivo. In parallel we generated PhiC31-based transgenic Drosophila melanogaster expressing wild type (WT) and Aβ40 and Aβ42 mutants, fused to the Argos signal peptide to assess the extent of Aβ42-induced toxicity as well as to interrogate the combined effect of different Aβ40 and Aβ42 species.Results When expressed in the mouse brain for 6 months, Aβ42 E22G, Aβ42 E22Q/D23N, and Aβ42WT formed amyloid aggregates consisting of some diffuse material as well as cored plaques, whereas other mutants formed predominantly diffuse amyloid deposits. Moreover, while Aβ40WT showed no distinctive phenotype, Aβ40 E22G and E22Q/D23N formed unique aggregates that accumulated in mouse brains. This is the first evidence that mutant Aβ40 overexpression leads to deposition under certain conditions. Interestingly, we found that mutant Aβ42 E22G, E22Q, and S26C, but not Aβ40, were toxic to the eye of Drosophila. In contrast, flies expressing a copy of Aβ40 (WT or mutants) in addition to Aβ42WT, showed improved phenotypes, suggesting possible protective qualities for Aβ40. Conclusions These studies suggest that while some Aβ40 mutants form unique amyloid aggregates in mouse brains, they do not exacerbate Aβ42 toxicity in Drosophila, which highlights the significance of using different systems for a better understanding of AD pathogenicity and more accurate screening for new potential therapies.

scholarly journals Aß40 displays amyloidogenic properties in the non-transgenic mouse brain but does not exacerbate Aß42 toxicity in Drosophila

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Lorena De Mena ◽  
Michael A. Smith ◽  
Jason Martin ◽  
Katie L. Dunton ◽  
Carolina Ceballos-Diaz ◽  
...  
Keyword(s):  
Mouse Brain ◽  
Self Assembly ◽  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Model Systems ◽  
Amyloid Angiopathy ◽  
Amyloid Deposits ◽  
Amyloid Aggregates ◽  
Amyloid Cascade

Abstract Background Self-assembly of the amyloid-β (Aβ) peptide into aggregates, from small oligomers to amyloid fibrils, is fundamentally linked with Alzheimer’s disease (AD). However, it is clear that not all forms of Aβ are equally harmful and that linking a specific aggregate to toxicity also depends on the assays and model systems used (Haass et al., J Biol. Chem 269:17741–17748, 1994; Borchelt et al., Neuron 17:1005–1013, 1996). Though a central postulate of the amyloid cascade hypothesis, there remain many gaps in our understanding regarding the links between Aβ deposition and neurodegeneration. Methods In this study, we examined familial mutations of Aβ that increase aggregation and oligomerization, E22G and ΔE22, and induce cerebral amyloid angiopathy, E22Q and D23N. We also investigated synthetic mutations that stabilize dimerization, S26C, and a phospho-mimetic, S8E, and non-phospho-mimetic, S8A. To that end, we utilized BRI2-Aβ fusion technology and rAAV2/1-based somatic brain transgenesis in mice to selectively express individual mutant Aβ species in vivo. In parallel, we generated PhiC31-based transgenic Drosophila melanogaster expressing wild-type (WT) and Aβ40 and Aβ42 mutants, fused to the Argos signal peptide to assess the extent of Aβ42-induced toxicity as well as to interrogate the combined effect of different Aβ40 and Aβ42 species. Results When expressed in the mouse brain for 6 months, Aβ42 E22G, Aβ42 E22Q/D23N, and Aβ42WT formed amyloid aggregates consisting of some diffuse material as well as cored plaques, whereas other mutants formed predominantly diffuse amyloid deposits. Moreover, while Aβ40WT showed no distinctive phenotype, Aβ40 E22G and E22Q/D23N formed unique aggregates that accumulated in mouse brains. This is the first evidence that mutant Aβ40 overexpression leads to deposition under certain conditions. Interestingly, we found that mutant Aβ42 E22G, E22Q, and S26C, but not Aβ40, were toxic to the eye of Drosophila. In contrast, flies expressing a copy of Aβ40 (WT or mutants), in addition to Aβ42WT, showed improved phenotypes, suggesting possible protective qualities for Aβ40. Conclusions These studies suggest that while some Aβ40 mutants form unique amyloid aggregates in mouse brains, they do not exacerbate Aβ42 toxicity in Drosophila, which highlights the significance of using different systems for a better understanding of AD pathogenicity and more accurate screening for new potential therapies.

scholarly journals Aß40 mutants protect Drosophila against Aß42 toxicity despite their amyloidogenic properties in the non-transgenic mouse brain

2020 ◽  
Author(s):  
Lorena de Mena ◽  
Michael A Smith ◽  
Jason Martin ◽  
Katie L Dunton ◽  
Carolina Ceballos-Diaz ◽  
...  
Keyword(s):  
Mouse Brain ◽  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Model Systems ◽  
Amyloid Angiopathy ◽  
Amyloid Deposits ◽  
Amyloid Aggregates ◽  
Amyloid Cascade ◽  
Transgenic Drosophila

Abstract BackgroundSelf-assembly of the amyloid-β (Aβ) peptide into aggregates, from small oligomers to amyloid fibrils, is fundamentally linked with Alzheimer’s disease (AD). However it is clear that not all forms of Aβ are equally harmful, and that linking a specific aggregate to toxicity also depends on the assays and model systems used [1, 2]. Though a central postulate of the amyloid cascade hypothesis, there remain many gaps in our understanding regarding the links between Aβ deposition and neurodegeneration.MethodsIn this study, we examined familial mutations of Aβ that increase aggregation and oligomerization, E22G and DE22, and induce cerebral amyloid angiopathy, E22Q and D23N. We also investigated synthetic mutations that stabilize dimerization, S26C, and a phospho-mimetic, S8E, and non-phospho-mimetic, S8A. To that end, we utilized BRI2-Aβ fusion technology and rAAV2/1 based somatic brain transgenesis in mice to selectively express individual mutant Aβ species in vivo . In parallel we generated PhiC31-based transgenic Drosophila melanogaster expressing wild type (WT) and Aβ40 and Aβ42 mutants, fused to the Argos signal peptide to assess the extent of Aβ42-induced toxicity as well as to interrogate the combined effect of different Aβ40 and Aβ42 species.ResultsWhen expressed in the mouse brain for 6 months, Aβ42 E22G, Aβ42 E22Q/D23N, and Aβ42WT formed amyloid aggregates consisting of some diffuse material as well as cored plaques, whereas other mutants formed predominantly diffuse amyloid deposits. Moreover, while Aβ40WT showed no distinctive phenotype, Aβ40 E22G and E22Q/D23N formed unique aggregates that accumulated in mouse brains. This is the first evidence that mutant Aβ40 overexpression leads to deposition under certain conditions. Interestingly, we found that mutant Aβ42 E22G, E22Q, and S26C, but not Aβ40, were toxic to the eye of Drosophila . In contrast, flies expressing a copy of Aβ40 (WT or mutants) in addition to Aβ42WT, showed improved phenotypes, suggesting possible protective qualities for Aβ40.ConclusionsThese studies suggest that some Aβ40 mutants form unique amyloid aggregates in mouse brains, despite protecting against Aβ42 toxicity in Drosophila , which highlights the significance of using different systems for a better understanding of AD pathogenicity and more accurate screening for new potential therapies.

scholarly journals Aß 40 Mutants Protect Drosophila Against aß 42 Toxicity Despite Their Amyloidogenic Properties in the Non-transgenic Mouse Brain

2020 ◽  
Author(s):  
Lorena de Mena ◽  
Michael Smith ◽  
Jason Martin ◽  
Katie L Dunton ◽  
Carolina Ceballos-Diaz ◽  
...  
Keyword(s):  
Mouse Brain ◽  
Amyloid Fibrils ◽  
Expression System ◽  
Amyloid Β ◽  
Model Systems ◽  
Amyloid Deposits ◽  
Amyloid Aggregates ◽  
Amyloid Cascade ◽  
Distinctive Phenotype

Abstract BackgroundSelf-assembly of the amyloid-β (Aβ) peptide into aggregates, ranging from small oligomers to amyloid fibrils, is fundamentally linked with Alzheimer’s disease (AD). However it is clear that not all forms of Aβ are equally harmful, and that linking a specific aggregate to toxicity also depends on the assays and model systems used [1, 2]. Indeed, though a central postulate of the amyloid cascade hypothesis, there remain many gaps in our understanding regarding the links between Aβ deposition and neurodegeneration.MethodsIn this study we utilized BRI2-Aβ fusion technology and rAAV2/1 based somatic brain transgenesis to examine Aβ aggregates that form from selective expression of individual mutant Aβ species in vivo. In parallel we generated PhiC31-based transgenic Drosophila melanogaster expressing WT and mutant Aβ40 and Aβ42, fused to the Argos signal peptide and placed under the GAL4-upstream activation sequence (UAS) expression system in order to assess the extent of Aβ42-induced toxicity as well as to interrogate the combined effect of different forms of Aβ40 and Aβ42 species.ResultsWhen expressed in the mouse brain for 6 months, Aβ42 E22G, Aβ42 E22Q/D23N, and Aβ42 WT formed amyloid aggregates consisting of some diffuse material as well as cored plaques, whereas other mutants formed predominantly diffuse amyloid deposits. Moreover, while Aβ40WT showed no distinctive phenotype, Aβ40 E22G and E22Q/D23N formed unique aggregates that accumulated in mouse brains. This is the first evidence that mutant Aβ40 overexpression leads to deposition under certain conditions. Interestingly, we found that mutant Aβ42 E22G, E22Q, and S26C, but not Aβ40, were toxic to the eye of the flies and exacerbated their behavior. In contrast, flies expressing a copy of Aβ40 (wild type [WT] or mutants) in addition to Aβ42 WT, showed improved phenotypes, suggesting possible protective qualities for Aβ40.ConclusionsThese studies suggest that some Aβ40 mutants form unique amyloid aggregates in mouse brains, despite being protective against Aβ42 toxicity in Drosophila, which highlights the significance of using different systems for a better understanding of AD pathogenicity and more accurate screening for new potential therapies.

Insights into amyloid disease from fly models

2014 ◽  
Vol 56 ◽  
pp. 69-83 ◽  
Author(s):  
Ko-Fan Chen ◽  
Damian C. Crowther
Keyword(s):  
Drosophila Melanogaster ◽  
Neurodegenerative Disorders ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Disease Pathogenesis ◽  
Amyloid Aggregates ◽  
Aβ Amyloid ◽  
Polypeptide Chains ◽  
Amyloid Diseases

The formation of amyloid aggregates is a feature of most, if not all, polypeptide chains. In vivo modelling of this process has been undertaken in the fruitfly Drosophila melanogaster with remarkable success. Models of both neurological and systemic amyloid diseases have been generated and have informed our understanding of disease pathogenesis in two main ways. First, the toxic amyloid species have been at least partially characterized, for example in the case of the Aβ (amyloid β-peptide) associated with Alzheimer's disease. Secondly, the genetic underpinning of model disease-linked phenotypes has been characterized for a number of neurodegenerative disorders. The current challenge is to integrate our understanding of disease-linked processes in the fly with our growing knowledge of human disease, for the benefit of patients.

scholarly journals The Amyloid Fibril-Forming β-Sheet Regions of Amyloid β and α-Synuclein Preferentially Interact with the Molecular Chaperone 14-3-3ζ

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6120
Author(s):  
Danielle M. Williams ◽  
David C. Thorn ◽  
Christopher M. Dobson ◽  
Sarah Meehan ◽  
Sophie E. Jackson ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Molecular Chaperones ◽  
Protein Unfolding ◽  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Parkinson’S Diseases ◽  
Amino Acid Form ◽  
Shock Proteins

14-3-3 proteins are abundant, intramolecular proteins that play a pivotal role in cellular signal transduction by interacting with phosphorylated ligands. In addition, they are molecular chaperones that prevent protein unfolding and aggregation under cellular stress conditions in a similar manner to the unrelated small heat-shock proteins. In vivo, amyloid β (Aβ) and α-synuclein (α-syn) form amyloid fibrils in Alzheimer’s and Parkinson’s diseases, respectively, a process that is intimately linked to the diseases’ progression. The 14-3-3ζ isoform potently inhibited in vitro fibril formation of the 40-amino acid form of Aβ (Aβ40) but had little effect on α-syn aggregation. Solution-phase NMR spectroscopy of 15N-labeled Aβ40 and A53T α-syn determined that unlabeled 14-3-3ζ interacted preferentially with hydrophobic regions of Aβ40 (L11-H21 and G29-V40) and α-syn (V3-K10 and V40-K60). In both proteins, these regions adopt β-strands within the core of the amyloid fibrils prepared in vitro as well as those isolated from the inclusions of diseased individuals. The interaction with 14-3-3ζ is transient and occurs at the early stages of the fibrillar aggregation pathway to maintain the native, monomeric, and unfolded structure of Aβ40 and α-syn. The N-terminal regions of α-syn interacting with 14-3-3ζ correspond with those that interact with other molecular chaperones as monitored by in-cell NMR spectroscopy.

Antibodies to β-Amyloid Decrease the Blood-to-Brain Transfer of β-Amyloid Peptide1

2002 ◽  
Vol 227 (8) ◽  
pp. 609-615 ◽  
Author(s):  
Weihong Pan ◽  
Beka Solomon ◽  
Lawrence M. Maness ◽  
Abba J. Kastin
Keyword(s):  
Ex Vivo ◽  
Amyloid Β ◽  
Brain Perfusion ◽  
Brain Parenchyma ◽  
Amyloid Angiopathy ◽  
Β Amyloid ◽  
Blocking Antibodies ◽  
The Brain

Amyloid-β peptides (Aβ) play an important role in the pathophysiology of dementia of the Alzheimer's type and in amyloid angiopathy. Aβ outside the CNS could contribute to plaque formation in the brain where its entry would involve interactions with the blood-brain barrier (BBB). Effective antibodies to Aβ have been developed in an effort to vaccinate against Alzheimer's disease. These antibodies could interact with Aβ in the peripheral blood, block the passage of Aβ across the BBB, or prevent Aβ deposition within the CNS. To determine whether the blocking antibodies act at the BBB level, we examined the influx of radiolabeled Aβ (125I-Aβ1-40) into the brain after ex-vivo incubation with the antibodies. Antibody mAb3D6 (élan Company) reduced the blood-to-brain influx of Aβ after iv bolus injection. It also significantly decreased the accumulation of Aβ in brain parenchyma. To confirm the in-vivo study and examine the specificity of mAb3D6, in-situ brain perfusion in serum-free buffer was performed after incubation of 125I-Aβ1-40 with another antibody mAbmc1 (DAKO Company). The presence of mAbmc1 also caused significant reduction of the influx of Aβ into the brain after perfusion. Therefore, effective antibodies to Aβ can reduce the influx of Aβ1-40 into the brain.

Studies with Radiolabelled Serum Amyloid P Component Provide Evidence for Turnover and Regression of Amyloid Deposits In Vivo

1994 ◽  
Vol 87 (3) ◽  
pp. 289-295 ◽  
Author(s):  
Philip N. Hawkins
Keyword(s):  
Amyloid Fibrils ◽  
Specific Binding ◽  
Serum Amyloid ◽  
Poor Correlation ◽  
Amyloid P Component ◽  
Serum Amyloid P ◽  
Serum Amyloid P Component ◽  
Amyloid Deposits ◽  
Amyloid P

1. Quantitative scintigraphic and turnover studies, utilizing the specific binding affinity of serum amyloid P component for amyloid fibrils, have been developed as a tool for evaluating amyloid deposits in vivo. 2. Serial studies in over 300 patients have shown characteristic, diagnostic tissue distributions of amyloid in different types of amyloidosis. There is generally a poor correlation between quantity of amyloid and associated organ dysfunction. 3. Contrary to previous expectations, regression of amyloid has been demonstrated systematically for the first time: AA, AL and variant transthyretin-associated amyloid deposits often regress rapidly, and sometimes completely, if the supply of fibril protein precursors is substantially reduced.

scholarly journals A serine protease secreted from Bacillus subtilis cleaves human plasma transthyretin to generate an amyloidogenic fragment

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Daniele Peterle ◽  
Giulia Pontarollo ◽  
Stefano Spada ◽  
Paola Brun ◽  
Luana Palazzi ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Human Plasma ◽  
Amyloid Fibrils ◽  
Wild Type ◽  
Senile Systemic Amyloidosis ◽  
Amyloid Deposits ◽  
Gut Mucosa ◽  
Standard Composition ◽  
Human Wild Type

AbstractAggregation of human wild-type transthyretin (hTTR), a homo-tetrameric plasma protein, leads to acquired senile systemic amyloidosis (SSA), recently recognised as a major cause of cardiomyopathies in 1–3% older adults. Fragmented hTTR is the standard composition of amyloid deposits in SSA, but the protease(s) responsible for amyloidogenic fragments generation in vivo is(are) still elusive. Here, we show that subtilisin secreted from Bacillus subtilis, a gut microbiota commensal bacterium, translocates across a simulated intestinal epithelium and cleaves hTTR both in solution and human plasma, generating the amyloidogenic fragment hTTR(59–127), which is also found in SSA amyloids in vivo. To the best of our knowledge, these findings highlight a novel pathogenic mechanism for SSA whereby increased permeability of the gut mucosa, as often occurs in elderly people, allows subtilisin (and perhaps other yet unidentified bacterial proteases) to reach the bloodstream and trigger generation of hTTR fragments, acting as seeding nuclei for preferential amyloid fibrils deposition in the heart.

scholarly journals Aβ(M1–40) and Wild-Type Aβ40 Self-Assemble into Oligomers with Distinct Quaternary Structures

Molecules ◽  
2019 ◽  
Vol 24 (12) ◽  
pp. 2242 ◽  
Author(s):  
Jacob L. Bouchard ◽  
Taylor C. Davey ◽  
Todd M. Doran
Keyword(s):  
Self Assembly ◽  
Quaternary Structure ◽  
Biological Activities ◽  
Amyloid Β ◽  
Long Term Potentiation ◽  
Wild Type ◽  
Molecular Weights ◽  
Term Potentiation ◽  
Quaternary Structures

Amyloid-β oligomers (AβOs) self-assemble into polymorphic species with diverse biological activities that are implicated causally to Alzheimer’s disease (AD). Synaptotoxicity of AβO species is dependent on their quaternary structure, however, low-abundance and environmental sensitivity of AβOs in vivo have impeded a thorough assessment of structure–function relationships. We developed a simple biochemical assay to quantify the relative abundance and morphology of cross-linked AβOs. We compared oligomers derived from synthetic Aβ40 (wild-type (WT) Aβ40) and a recombinant source, called Aβ(M1–40). Both peptides assemble into oligomers with common sizes and morphology, however, the predominant quaternary structures of Aβ(M1–40) oligomeric states were more diverse in terms of dispersity and morphology. We identified self-assembly conditions that stabilize high-molecular weight oligomers of Aβ(M1–40) with apparent molecular weights greater than 36 kDa. Given that mixtures of AβOs derived from both peptides have been shown to be potent neurotoxins that disrupt long-term potentiation, we anticipate that the diverse quaternary structures reported for Aβ(M1–40) oligomers using the assays reported here will facilitate research efforts aimed at isolating and identifying common toxic species that contribute to synaptic dysfunction.

scholarly journals Lipid membranes trigger misfolding and self-assembly of amyloid β 42 protein into aggregates

2019 ◽  
Author(s):  
Siddhartha Banerjee ◽  
Mohtadin Hashemi ◽  
Karen Zagorski ◽  
Yuri L. Lyubchenko
Keyword(s):  
Self Assembly ◽  
Lipid Membranes ◽  
Membrane Surface ◽  
Amyloid Β ◽  
Test Tube ◽  
Aggregation Process ◽  
Self Assembling ◽  
Nanoscale Aggregates

AbstractThe assembly of polypeptides and proteins into nanoscale aggregates is a phenomenon observed in a vast majority of proteins. Importantly, aggregation of amyloid β (Aβ) proteins is considered as a major cause for the development of Alzheimer’s disease. The process depends on various conditions and typical test-tube experiments require high protein concentration that complicates the translation of results obtained in vitro to understanding the aggregation process in vivo. Here we demonstrate that Aβ42 monomers at the membrane bilayer are capable of self-assembling into aggregates at physiologically low concentrations, and the membrane in this aggregation process plays a role of a catalyst. We applied all-atom molecular dynamics to demonstrate that the interaction with the membrane surface dramatically changes the conformation of Aβ42 protein. As a result, the misfolded Aβ42 rapidly assembles into dimers, trimers and tetramers, so the on-surface aggregation is the mechanism by which amyloid oligomers are produced and spread.

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