scholarly journals Effects of Aβ-derived peptide fragments on fibrillogenesis of Aβ

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Faisal Abedin ◽  
Nabin Kandel ◽  
Suren A. Tatulian
Keyword(s):  
Resonance Energy Transfer ◽  
Amyloid Β ◽  
Resonance Energy ◽  
Inhibitory Effect ◽  
Peptide Fragments ◽  
Drug Candidates ◽  
High Propensity ◽  
Peptide Interactions ◽  
Strong Inhibitory Effect ◽  
Β Sheet

AbstractAmyloid β (Aβ) peptide aggregation plays a central role in Alzheimer’s disease (AD) etiology. AD drug candidates have included small molecules or peptides directed towards inhibition of Aβ fibrillogenesis. Although some Aβ-derived peptide fragments suppress Aβ fibril growth, comprehensive analysis of inhibitory potencies of peptide fragments along the whole Aβ sequence has not been reported. The aim of this work is (a) to identify the region(s) of Aβ with highest propensities for aggregation and (b) to use those fragments to inhibit Aβ fibrillogenesis. Structural and aggregation properties of the parent Aβ1–42 peptide and seven overlapping peptide fragments have been studied, i.e. Aβ1–10 (P1), Aβ6–15 (P2), Aβ11–20 (P3), Aβ16–25 (P4), Aβ21–30 (P5), Aβ26–36 (P6), and Aβ31–42 (P7). Structural transitions of the peptides in aqueous buffer have been monitored by circular dichroism and Fourier transform infrared spectroscopy. Aggregation and fibrillogenesis were analyzed by light scattering and thioflavin-T fluorescence. The mode of peptide-peptide interactions was characterized by fluorescence resonance energy transfer. Three peptide fragments, P3, P6, and P7, exhibited exceptionally high propensity for β-sheet formation and aggregation. Remarkably, only P3 and P6 exerted strong inhibitory effect on the aggregation of Aβ1–42, whereas P7 and P2 displayed moderate inhibitory potency. It is proposed that P3 and P6 intercalate between Aβ1–42 molecules and thereby inhibit Aβ1–42 aggregation. These findings may facilitate therapeutic strategies of inhibition of Aβ fibrillogenesis by Aβ-derived peptides.

scholarly journals Live Cell FRET Imaging Reveals Amyloid β-Peptide Oligomerization in Hippocampal Neurons

2021 ◽  
Author(s):  
Yang Gao ◽  
Stefan Wennmalm ◽  
Bengt Winblad ◽  
Sophia Schedin-Weiss ◽  
Lars Tjernberg
Keyword(s):  
Hippocampal Neurons ◽  
Resonance Energy Transfer ◽  
Amyloid Β ◽  
Resonance Energy ◽  
Live Cell ◽  
Amyloid Β Peptide ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Late Endosomes ◽  
Aβ Oligomerization

Amyloid β-peptide (Aβ) oligomerization is believed to contribute to the neuronal dysfunction in Alzheimer disease (AD). Despite decades of research, many details of Aβ oligomerization in neurons still need to be revealed. Förster Resonance Energy Transfer (FRET) is a simple but effective way to study molecular interactions. Here we use a confocal microscope with a sensitive Airyscan detector for FRET detection. By live cell FRET imaging, we detect Aβ42 oligomerization in primary neurons. The neurons were incubated with fluorescently labelled Aβ42 in the cell culture medium for 24 hours. Aβ42 were internalized and oligomerized into the lysosomes/late endosomes in a concentration-dependent manner. Both the cellular uptake and intracellular oligomerization of Aβ42 were significantly higher than for Aβ40. These findings provide a better understanding of Aβ42 oligomerization in neurons.

scholarly journals Enhanced efficacy of endonuclease inhibitor baloxavir acid against orthobunyaviruses when used in combination with ribavirin

2020 ◽  
Vol 75 (11) ◽  
pp. 3189-3193
Author(s):  
Sebastiaan ter Horst ◽  
Yaiza Fernandez-Garcia ◽  
Marcella Bassetto ◽  
Stephan Günther ◽  
Andrea Brancale ◽  
...  
Keyword(s):  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Docking Simulation ◽  
Antiviral Effect ◽  
Inhibitory Effect ◽  
Surface Model ◽  
La Crosse Virus ◽  
Endonuclease Domain ◽  
Substrate Cleavage

Abstract Objectives Baloxavir acid is an endonuclease inhibitor approved for use against influenza. We evaluated whether this compound also targets the endonuclease domain of orthobunyaviruses and therefore could potentially be used against orthobunyavirus infections. Methods We performed a thermal shift assay and a fluorescence resonance energy transfer (FRET)-based nuclease monitoring assay using the La Crosse virus (LACV) endonuclease and baloxavir acid to prove their interaction and identify an inhibitory effect. Their interaction was further studied in a docking simulation using Glide SP. We show that baloxavir acid inhibits the viral replication of Bunyamwera virus (BUNV)–mCherry in vitro using high-content imaging and virus yield assay. Lastly, we investigated the use of baloxavir acid in combination with ribavirin in vitro by implementing the Zero Interaction Potency response surface model. Results We show that baloxavir acid augments LACV enzyme’s melting temperature with ΔTm 9.5 ± 0.4°C and inhibited substrate cleavage with IC50 0.39 ± 0.03 μM. Moreover, our docking simulation suggests that baloxavir acid is able to establish an efficient binding with the LACV endonuclease. In the cell-based assay, we observed that baloxavir acid and ribavirin inhibited BUNV–mCherry with an EC50 of 0.7 ± 0.2 μM and 26.6 ± 8.9 μM, respectively. When used in combination, we found a maximum synergistic effect of 8.64. Conclusions The influenza endonuclease inhibitor baloxavir acid is able to bind to and interfere with the endonuclease domain of orthobunyaviruses and yields a more potent antiviral effect than ribavirin against BUNV–mCherry. The combination of both compounds results in a more potent antiviral effect, suggesting that these molecules could potentially be combined to treat orthobunyavirus-infected patients.

scholarly journals Amyloid β-peptides interfere with mitochondrial preprotein import competence by a coaggregation process

2016 ◽  
Vol 27 (21) ◽  
pp. 3257-3272 ◽  
Author(s):  
Giovanna Cenini ◽  
Cornelia Rüb ◽  
Michael Bruderek ◽  
Wolfgang Voos
Keyword(s):  
Mitochondrial Protein ◽  
Amyloid Β ◽  
Inhibitory Effect ◽  
Cellular Damage ◽  
Aβ Peptides ◽  
Mitochondrial Functions ◽  
Major Species ◽  
Protein Biogenesis ◽  
Precursor Proteins ◽  
Strong Inhibitory Effect

Aβ peptides play a central role in the etiology of Alzheimer disease (AD) by exerting cellular toxicity correlated with aggregate formation. Experimental evidence has shown intraneuronal accumulation of Aβ peptides and interference with mitochondrial functions. Nevertheless, the relevance of intracellular Aβ peptides in the pathophysiology of AD is controversial. Here we found that the two major species of Aβ peptides, in particular Aβ42, exhibited a strong inhibitory effect on the preprotein import reactions essential for mitochondrial biogenesis. However, Aβ peptides interacted only weakly with mitochondria and did not affect the inner membrane potential or the structure of the preprotein translocase complexes. Aβ peptides significantly decreased the import competence of mitochondrial precursor proteins via an extramitochondrial coaggregation mechanism. Coaggregation and import inhibition were significantly stronger for the longer peptide Aβ42, correlating with its importance in AD pathology. Our results demonstrate that direct interference of aggregation-prone Aβ peptides with mitochondrial protein biogenesis represents a crucial aspect of the pathobiochemical mechanisms contributing to cellular damage in AD.

scholarly journals Interference with Amyloid-β Nucleation by Transient Ligand Interaction

Molecules ◽  
2019 ◽  
Vol 24 (11) ◽  
pp. 2129 ◽  
Author(s):  
Tao Zhang ◽  
Jennifer Loschwitz ◽  
Birgit Strodel ◽  
Luitgard Nagel-Steger ◽  
Dieter Willbold
Keyword(s):  
Amyloid Β ◽  
Intrinsically Disordered Protein ◽  
Amyloid Β Peptide ◽  
Amino Acid Residues ◽  
Ligand Interaction ◽  
Drug Candidates ◽  
Intrinsically Disordered ◽  
Disordered Protein ◽  
First Time ◽  
Β Sheet

Amyloid-β peptide (Aβ) is an intrinsically disordered protein (IDP) associated with Alzheimer’s disease. The structural flexibility and aggregation propensity of Aβ pose major challenges for elucidating the interaction between Aβ monomers and ligands. All-D-peptides consisting solely of D-enantiomeric amino acid residues are interesting drug candidates that combine high binding specificity with high metabolic stability. Here we characterized the interaction between the 12-residue all-D-peptide D3 and Aβ42 monomers, and how the interaction influences Aβ42 aggregation. We demonstrate for the first time that D3 binds to Aβ42 monomers with submicromolar affinities. These two highly unstructured molecules are able to form complexes with 1:1 and other stoichiometries. Further, D3 at substoichiometric concentrations effectively slows down the β-sheet formation and Aβ42 fibrillation by modulating the nucleation process. The study provides new insights into the molecular mechanism of how D3 affects Aβ assemblies and contributes to our knowledge on the interaction between two IDPs.

scholarly journals AlphaScreen HTS and Live-Cell Bioluminescence Resonance Energy Transfer (BRET) Assays for Identification of Tau–Fyn SH3 Interaction Inhibitors for Alzheimer Disease

2014 ◽  
Vol 19 (10) ◽  
pp. 1338-1349 ◽  
Author(s):  
J. Nicholas Cochran ◽  
Pauleatha V. Diggs ◽  
N. Miranda Nebane ◽  
Lynn Rasmussen ◽  
E. Lucile White ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Alzheimer Disease ◽  
High Throughput Screening ◽  
Resonance Energy Transfer ◽  
Amyloid Β ◽  
Resonance Energy ◽  
Live Cell ◽  
Dominant Negative ◽  
Bioluminescence Resonance Energy Transfer ◽  
Bret Assay

Alzheimer disease (AD) is the most common neurodegenerative disease, and with Americans’ increasing longevity, it is becoming an epidemic. There are currently no effective treatments for this disorder. Abnormalities of Tau track more closely with cognitive decline than the most studied therapeutic target in AD, amyloid-β, but the optimal strategy for targeting Tau has not yet been identified. On the basis of considerable preclinical data from AD models, we hypothesize that interactions between Tau and the Src-family tyrosine kinase, Fyn, are pathogenic in AD. Genetically reducing either Tau or Fyn is protective in AD mouse models, and a dominant negative fragment of Tau that alters Fyn localization is also protective. Here, we describe a new AlphaScreen assay and a live-cell bioluminescence resonance energy transfer (BRET) assay using a novel BRET pair for quantifying the Tau–Fyn interaction. We used these assays to map the binding site on Tau for Fyn to the fifth and sixth PXXP motifs to show that AD-associated phosphorylation at microtubule affinity regulating kinase sites increases the affinity of the Tau–Fyn interaction and to identify Tau–Fyn interaction inhibitors by high-throughput screening. This screen has identified a variety of chemically tractable hits, suggesting that the Tau–Fyn interaction may represent a good drug target for AD.

scholarly journals A Novel Role of Nectins in Inhibition of the E-Cadherin–induced Activation of Rac and Formation of Cell-Cell Adherens Junctions

2004 ◽  
Vol 15 (3) ◽  
pp. 1077-1088 ◽  
Author(s):  
Takashi Hoshino ◽  
Kazuya Shimizu ◽  
Tomoyuki Honda ◽  
Tomomi Kawakatsu ◽  
Taihei Fukuyama ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
G Protein ◽  
Adherens Junctions ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Inhibitory Effect ◽  
Small G Protein ◽  
E Cadherin ◽  
Cell Cell

Nectins are Ca2+-independent immunoglobulin (Ig)-like cell-cell adhesion molecules. The trans-interactions of nectins recruit cadherins to the nectin-based cell-cell adhesion, resulting in formation of cell-cell adherens junctions (AJs) in epithelial cells and fibroblasts. The trans-interaction of E-cadherin induces activation of Rac small G protein, whereas the trans-interactions of nectins induce activation of not only Rac but also Cdc42 small G protein. We showed by the fluorescent resonance energy transfer (FRET) imaging that the trans-interaction of E-cadherin induced dynamic activation and inactivation of Rac, which led to dynamic formation and retraction of lamellipodia. Moreover, we found here that the nectins, which did not trans-interact with other nectins (non–trans-interacting nectins), inhibited the E-cadherin–induced activation of Rac and reduced the velocity of the formation of the E-cadherin-based cell-cell AJs. The inhibitory effect of non–trans-interacting nectins was suppressed by the activation of Cdc42 induced by the trans-interactions of nectins. These results indicate a novel role of nectins in regulation of the E-cadherin–induced activation of Rac and formation of cell-cell AJs.

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