A rationally designed bicyclic peptide remodels Aβ42 aggregation in vitro and reduces its toxicity in a worm model of Alzheimer’s disease

Alzheimer’s disease, which is the most common form of dementia, is characterized by the aggregation of the amyloid β peptide (Aβ) and by an impairment of calcium homeostasis caused by excessive activation of glutamatergic receptors (excitotoxicity). Here, we studied the effects on calcium homeostasis caused by the formation of Aβ oligomeric assemblies. We found that Aβ oligomers cause a rapid influx of calcium ions (Ca 2+ ) across the cell membrane by rapidly activating extrasynaptic N -methyl- d -aspartate (NMDA) receptors and, to a lower extent, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. We also observed, however, that misfolded oligomers do not interact directly with these receptors. Further experiments with lysophosphatidylcholine and arachidonic acid, which cause membrane compression and stretch, respectively, indicated that these receptors are activated through a change in membrane tension induced by the oligomers and transmitted mechanically to the receptors via the lipid bilayer. Indeed, lysophosphatidylcholine is able to neutralize the oligomer-induced activation of the NMDA receptors, whereas arachidonic acid activates the receptors similarly to the oligomers with no additive effects. An increased rotational freedom observed for a fluorescent probe embedded within the membrane in the presence of the oligomers also indicates a membrane stretch. These results reveal a mechanism of toxicity of Aβ oligomers in Alzheimer’s disease through the perturbation of the mechanical properties of lipid membranes sensed by NMDA and AMPA receptors.

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“…The zinc-stabilized Aβ 40 oligomers morphology and size were routinely verified in our laboratories. 69 − 71 …”

Section: Materials and Methodsmentioning

confidence: 99%

Aβ Oligomers Dysregulate Calcium Homeostasis by Mechanosensitive Activation of AMPA and NMDA Receptors

Fani

Mannini

Vecchi

et al. 2021

ACS Chem. Neurosci.

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“…We employed the cascade method, a computational antibody discovery strategy (Sormanni et al, 2015a(Sormanni et al, , 2018Ikenoue et al, 2020), to generate six bicyclic peptides targeting different regions of the amino acid sequence of Aβ42 (section "Materials and Methods"). These six peptides (DesBP1-DesBP6) were designed to scan epitopes in the most amyloidogenic region of Aβ42 (residues 13-42) ( Figure 1A) (section "Materials and Methods").…”

Section: Rational Design and Synthesis Of Bicyclic Peptides Targetingmentioning

confidence: 99%

“…In order to investigate the effects of the DesBPs on Aβ42 aggregation, we carried out in vitro aggregation assays using the fluorescent dye thioflavin T (ThT) as amyloid-sensitive probe. We monitored Aβ42 fibril formation at the concentration of 2 µM in the presence of different molar ratios [Aβ42]:[DesBP] (from 0.05 to 16) at 37 • C under quiescent conditions, using a highly reproducible aggregation assay previously described (Hellstrand et al, 2010;Ikenoue et al, 2020).…”

Section: Characterization Of the Effects Of The Desbps On The Aggregamentioning

confidence: 99%

“…The obtained DesAbs in their monomeric forms were diluted with buffer to the desired concentration and supplemented with 20 µM ThT and 50 µM ANS from a 1 mM stock. ANS experiments were carried out as described previously (Ikenoue et al, 2020). Seeding experiments were performed in the presence of 10% (v/v) preformed fibrils, as described previously (Ikenoue et al, 2020).…”

Section: Tht and Ans Fluorescence Aggregation Assaymentioning

confidence: 99%

“…This method, however, may become time-consuming and at times ineffective, in particular when one aims at targeting aggregation-prone antigens or weakly immunogenic epitopes. To overcome these limitations, we have introduced a method for the rationally design of antibodies (Aprile et al, 2015(Aprile et al, , 2017Sormanni et al, 2015aSormanni et al, , 2018 and bicyclic peptides (Ikenoue et al, 2020), which enables the targeting of specific epitopes within intrinsically disordered proteins.…”

Section: Introductionmentioning

confidence: 99%

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Rationally Designed Bicyclic Peptides Prevent the Conversion of Aβ42 Assemblies Into Fibrillar Structures

et al. 2021

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There is great interest in drug discovery programs targeted at the aggregation of the 42-residue form of the amyloid β peptide (Aβ42), since this molecular process is closely associated with Alzheimer’s disease. The use of bicyclic peptides may offer novel opportunities for the effective modification of Aβ42 aggregation and the inhibition of its cytotoxicity, as these compounds combine the molecular recognition ability of antibodies with a relatively small size of about 2 kD. Here, to pursue this approach, we rationally designed a panel of six bicyclic peptides targeting various epitopes along the sequence of Aβ42 to scan its most amyloidogenic region (residues 13–42). Our kinetic analysis and structural studies revealed that at sub-stoichiometric concentrations the designed bicyclic peptides induce a delay in the condensation of Aβ42 and the subsequent transition to a fibrillar state, while at higher concentrations they inhibit such transition. We thus suggest that designed bicyclic peptides can be employed to inhibit amyloid formation by redirecting the aggregation process toward amorphous assemblies.

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Structural and biological aspects of natural bridged macrobicyclic peptides from marine resources

Dahiya

Kumar

et al. 2021

Archiv der Pharmazie

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Among peptide‐based drugs, naturally occurring bicyclic compounds have been established as molecules with unique therapeutic potential. The diverse pharmacological activities associated with bicyclic peptides from marine tunicates, sponges, and bacteria render them suitable to be employed as effective surrogate between complex and small therapeutic moieties. Bicyclic peptides possess greater conformational rigidity and higher metabolic stability as compared with linear and monocyclic peptides. The antibody‐like affinity and specificity of bicyclic peptides enable their binding to the challenging drug targets. Bridged macrobicyclic peptides from natural marine resources represent an underexplored class of molecules that provides promising platforms for drug development owing to their biocompatibility, similarity, and chemical diversity to proteins. The present review explores major marine‐derived bicyclic peptides including disulfide‐bridged, histidinotyrosine‐bridged, or histidinoalanine‐bridged macrobicyclic peptides along with their structural characteristics, synthesis, structure–activity relationship, and bioproperties.The comparison of these macrobicyclic congeners with linear/monocyclic peptides along with their therapeutic potential are also briefly discussed.

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A rationally designed bicyclic peptide remodels Aβ42 aggregation in vitro and reduces its toxicity in a worm model of Alzheimer’s disease

Cited by 16 publications

References 96 publications

Aβ Oligomers Dysregulate Calcium Homeostasis by Mechanosensitive Activation of AMPA and NMDA Receptors

Aβ Oligomers Dysregulate Calcium Homeostasis by Mechanosensitive Activation of AMPA and NMDA Receptors

Rationally Designed Bicyclic Peptides Prevent the Conversion of Aβ42 Assemblies Into Fibrillar Structures

Structural and biological aspects of natural bridged macrobicyclic peptides from marine resources

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