Detection of amyloid-β fibrils using the DNA-intercalating dye YOYO-1: Binding mode and fibril formation kinetics

Lindberg, David; Esbjörner, Elin K.

doi:10.1016/j.bbrc.2015.11.051

Cited by 11 publications

(9 citation statements)

References 32 publications

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“…To cover this pH range, a citrate-phosphate buffer was used, which required an increase in the ionic strength to 200 mM compared to the data presented in Figure 2 in order to obtain sufficient buffering capacity at pH 5.0. This in itself decreased the half-time of Aβ(1-42) aggregation from 0.82 ± 0.03 h (20 mM) to 0.20 ± 0.01 h (200 mM) ( Figure 3a), consistent with previous observations of salt effects [91,92] and a recent study demonstrating that increased electrostatic screening enhances several mechanistic steps in the self-assembly of Aβ(1-42) [93]. We found that Cu 2+ slows down Aβ(1-42) aggregation also in 200 mM salt, pH 8.0, (Figure 3b), but the effect is weaker (1.4 times increase in the half-time at 5.2 μM of Cu 2+ (Figure 3c) compared to a 4.6 times increase at 20 mM of salt (Figure 2a)).…”

Section: Ph and Salt Dependence Of The Cu 2+ -Mediated Inhibition Of supporting

confidence: 91%

Redox-Dependent Copper Ion Modulation of Amyloid-β (1-42) Aggregation In Vitro

et al. 2020

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Plaque deposits composed of amyloid-β (Aβ) fibrils are pathological hallmarks of Alzheimer’s disease (AD). Although copper ion dyshomeostasis is apparent in AD brains and copper ions are found co-deposited with Aβ peptides in patients’ plaques, the molecular effects of copper ion interactions and redox-state dependence on Aβ aggregation remain elusive. By combining biophysical and theoretical approaches, we here show that Cu2+ (oxidized) and Cu+ (reduced) ions have opposite effects on the assembly kinetics of recombinant Aβ(1-42) into amyloid fibrils in vitro. Cu2+ inhibits both the unseeded and seeded aggregation of Aβ(1-42) at pH 8.0. Using mathematical models to fit the kinetic data, we find that Cu2+ prevents fibril elongation. The Cu2+-mediated inhibition of Aβ aggregation shows the largest effect around pH 6.0 but is lost at pH 5.0, which corresponds to the pH in lysosomes. In contrast to Cu2+, Cu+ ion binding mildly catalyzes the Aβ(1-42) aggregation via a mechanism that accelerates primary nucleation, possibly via the formation of Cu+-bridged Aβ(1-42) dimers. Taken together, our study emphasizes redox-dependent copper ion effects on Aβ(1-42) aggregation and thereby provides further knowledge of putative copper-dependent mechanisms resulting in AD.

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Section: Ph and Salt Dependence Of The Cu 2+ -Mediated Inhibition Of supporting

confidence: 91%

Redox-Dependent Copper Ion Modulation of Amyloid-β (1-42) Aggregation In Vitro

et al. 2020

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“…They showed [239] that these dyes too would bind to β-amyloid fibrils, albeit not normally (but cf. [240]) with quite with the same fluorescence enhancement as shown by…”

Section: Thioflavin S Thioflavin T and Derivativessupporting

confidence: 76%

Substoichiometric molecular control and amplification of the initiation and nature of amyloid fibril formation: lessons from and for blood clotting

Pretorius

2016

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The chief and largely terminal element of normal blood clotting is considered to involve the polymerisation of the mainly α-helical fibrinogen to fibrin, with a binding mechanism involving ‘knobs and holes’ but with otherwise littl change in protein secondary structure. We recognise, however, that extremely unusual mutations, or mechanical stressing, can cause fibrinogen to adopt a conformation containing extensive β-sheets. Similarly, prions can change morphology from a largely alpha-helical to a largely β-sheet conformation, and the latter catalyses both the transition and the self-organising polymerisation of the β-sheet structures. Many other proteins can do this, where it is known as amyloidogenesis. When fibrin is formed in samples from patients harbouring different diseases it can have widely varying diameters and morphologies. We here develop the idea, and summarise the evidence, that in many cases the anomalous fibrin fibre formation seen in such diseases actually amounts to amyloidogenesis. In particular, fibrin can interact withthe amyloid-β (Aβ) protein that is misfolded in Alzheimer's disease. Seeing these unusual fibrin morphologies as true amyloids explains a great deal about fibrin(ogen) biology that was previously opaque, and provides novel strategies for treating such coagulopathies. The literature on blood clotting can usefully both inform and be informed by that on prions and on the many other widely recognised (β)-amyloid proteins.“Novel but physiologically important factors that affect fibrinolysis have seldom been discovered and characterized in recent years” [1]

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“…Hence, the two additional C-terminal hydrophobic residues in the primary sequence of the latter variant appear decisive for its superior uptake. We base this conclusion on that we observe differences in uptake already after 1 h; this time span is insufficient to lead to aggregation at the extracellular concentrations we supply (≤1 μM), even for Aβ(1–42) 52 which has an intrinsic higher amyloid formation propensity than Aβ(1–40) 53 . Moreover, we do not observe extensive accumulation of the Aβ variants at the cell surface prior to uptake; accelerated amyloid growth or oligomer formation in this vicinity 54 prior to uptake is thus unlikely.…”

Section: Discussionmentioning

confidence: 84%

Endocytic uptake of monomeric amyloid-β peptides is clathrin- and dynamin-independent and results in selective accumulation of Aβ(1–42) compared to Aβ(1–40)

Wesén

Jeffries

Dzebo

et al. 2017

Sci Rep

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104

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Intraneuronal accumulation of amyloid-β (Aβ) peptides represent an early pathological feature in Alzheimer’s disease. We have therefore utilized flow cytometry and confocal microscopy in combination with endocytosis inhibition to explore the internalisation efficiency and uptake mechanisms of Aβ(1–40) and Aβ(1–42) monomers in cultured SH-SY5Y cells. We find that both variants are constitutively internalised via endocytosis and that their uptake is proportional to cellular endocytic rate. Moreover, SH-SY5Y cells internalise consistently twice the amount of Aβ(1–42) compared to Aβ(1–40); an imaging-based quantification showed that cells treated with 1 µM peptide for 8 h contained 800,000 peptides of Aβ(1–42) and 400,000 of Aβ(1–40). Both variants co-localised to >90% with lysosomes or other acidic compartments. Dynasore and chlorpromazine endocytosis inhibitors were both found to reduce uptake, particularly of Aβ(1–42). Overexpression of the C-terminal of the clathrin-binding domain of AP180, dynamin2 K44A, or Arf6 Q67L did however not reduce uptake of the Aβ variants. By contrast, perturbation of actin polymerisation and inhibition of macropinocytosis reduced Aβ(1–40) and Aβ(1–42) uptake considerably. This study clarifies mechanisms of Aβ(1–40) and Aβ(1–42) uptake, pinpoints differences between the two variants and highlights a common and putative role of macropinocytosis in the early accumulation of intraneuronal Aβ in AD.

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Detection of amyloid-β fibrils using the DNA-intercalating dye YOYO-1: Binding mode and fibril formation kinetics

Cited by 11 publications

References 32 publications

Redox-Dependent Copper Ion Modulation of Amyloid-β (1-42) Aggregation In Vitro

Redox-Dependent Copper Ion Modulation of Amyloid-β (1-42) Aggregation In Vitro

Substoichiometric molecular control and amplification of the initiation and nature of amyloid fibril formation: lessons from and for blood clotting

Endocytic uptake of monomeric amyloid-β peptides is clathrin- and dynamin-independent and results in selective accumulation of Aβ(1–42) compared to Aβ(1–40)

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