Toxic effects of amyloid fibrils on cell membranes: the importance of ganglioside GM1

Bucciantini, Monica; Nosi, Daniele; Forzan, Mario; Russo, Edda; Calamai, Martino; Pieri, Laura; Formigli, Lucia; Quercioli, Franco; Soria, Silvia; Pavone, Francesco S.; Savistchenko, Jimmy; Melki, Ronald; Stefani, Massimo

doi:10.1096/fj.11-189381

Cited by 117 publications

(101 citation statements)

References 69 publications

(90 reference statements)

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“…In this case, a sharp point is also drawn out from the target membrane, as is observed with short β 2 m amyloid fibrils, but instead of destroying the liposome, the destabilized, extruded membrane region is fused to the viral membrane. The cryoelectron tomography images of β 2 m fibril-membrane interactions presented here suggest that the cellular dysfunction associated with these and other fibrils or fibril-like assemblies (16)(17)(18)(19)(20)(21)27) involves direct bilayer disruption. This membrane damage might arise by direct interaction with the fibril ends and/ or by the creation of new, toxic species by reaction of the fibril ends with the lipids.…”

Section: Discussionmentioning

confidence: 77%

“…In other cases, toxicity may reside with the amyloid fibrils themselves. Evidence that toxicity correlates with fibrillar assemblies has been reported for yeast and mammalian prion proteins (16,17), human lysozyme (18), Huntingtin exon 1, α-synuclein (19), and Amyloid-β (Aβ) (20,21). Furthermore, Aβ plaques have been shown to form rapidly in vivo and to precede neuropathological changes in a mouse model (22).…”

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confidence: 99%

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Direct three-dimensional visualization of membrane disruption by amyloid fibrils

Milanesi

Sheynis

Xue

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

169

177

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Protein misfolding and aggregation cause serious degenerative conditions such as Alzheimer's, Parkinson, and prion diseases. Damage to membranes is thought to be one of the mechanisms underlying cellular toxicity of a range of amyloid assemblies. Previous studies have indicated that amyloid fibrils can cause membrane leakage and elicit cellular damage, and these effects are enhanced by fragmentation of the fibrils. Here we report direct 3D visualization of membrane damage by specific interactions of a lipid bilayer with amyloid-like fibrils formed in vitro from β 2 -microglobulin (β 2 m). Using cryoelectron tomography, we demonstrate that fragmented β 2 m amyloid fibrils interact strongly with liposomes and cause distortions to the membranes. The normally spherical liposomes form pointed teardrop-like shapes with the fibril ends seen in proximity to the pointed regions on the membranes. Moreover, the tomograms indicated that the fibrils extract lipid from the membranes at these points of distortion by removal or blebbing of the outer membrane leaflet. Tiny (15-25 nm) vesicles, presumably formed from the extracted lipids, were observed to be decorating the fibrils. The findings highlight a potential role of fibrils, and particularly fibril ends, in amyloid pathology, and report a previously undescribed class of lipid-protein interactions in membrane remodelling.T he failure of molecular chaperones to prevent the accumulation of misfolded proteins results in protein aggregation and amyloid formation, processes associated with severe human degenerative diseases (1, 2). Despite the attention focused on these problems during the century since these disorders were first identified (3-5) and advances in understanding the structure of the cross-β conformation of amyloid fibrils in atomic detail (6, 7), the basic pathological mechanisms of amyloidosis remain poorly understood and therapeutic intervention is lacking. The identity of the toxic species and the mechanisms of cytotoxicity remain major unsolved problems. In some systems, there is evidence suggesting that prefibrillar oligomers, rather than the fully formed fibrils, are the source of toxicity (8, 9). In these cases, cytotoxicity is thought to result from the formation of specific membrane pores (10, 11) although alternative models including membrane destabilization or membrane thinning have also been proposed (12-15). In other cases, toxicity may reside with the amyloid fibrils themselves. Evidence that toxicity correlates with fibrillar assemblies has been reported for yeast and mammalian prion proteins (16, 17), human lysozyme (18), Huntingtin exon 1, α-synuclein (19), and Amyloid-β (Aβ) (20, 21). Furthermore, Aβ plaques have been shown to form rapidly in vivo and to precede neuropathological changes in a mouse model (22). The end surfaces of fibrils (herein termed "fibril ends") are unusually reactive entities: they play a key role in catalyzing recruitment and conformational conversion of amyloid-forming proteins (23, 24) and provide the sites for templated...

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Section: Discussionmentioning

confidence: 77%

mentioning

confidence: 99%

Direct three-dimensional visualization of membrane disruption by amyloid fibrils

Milanesi

Sheynis

Xue

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

169

177

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“…found to be cytotoxic [3][4][5][6] or to induce the dysfunction of neurons and neuronal loss [7]. The binding of anle138b might inhibit aggregate growth and/or could reduce the toxicity of the aggregates and hamper disease progression as observed in in vivo experiments [16].…”

Section: Tablementioning

confidence: 99%

“…These aggregates, located in the brain of infected individuals, are characterized by a cross-β-sheet protein structure and a fibrillar morphology under the electron microscope. The amyloid aggregates are considered to play an important role in the pathogenesis of neurodegenerative diseases [3][4][5][6][7]. Furthermore, recent experiments pointed out that not only the fibrillar structures but especially the formation of smaller, highly cytotoxic oligomeric forms [8] might lead to neuronal loss [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates

Deeg

Reiner

Schmidt

et al. 2015

Biochimica et Biophysica Acta (BBA) - General Subjects

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Background: Special diphenyl-pyrazole compounds and in particular anle138b were found to reduce the progression of prion and Parkinson's disease in animal models. The therapeutic impact of these compounds was attributed to the modulation of α-synuclein and prion-protein aggregation related to these diseases. Methods: Photophysical and photochemical properties of the diphenyl-pyrazole compounds anle138b, anle186b and sery313b and their interaction with monomeric and aggregated α-synuclein were studied by fluorescence techniques. Results: The fluorescence emission of diphenyl-pyrazole is strongly increased upon incubation with α-synuclein fibrils, while no change in fluorescence emission is found when brought in contact with monomeric α-synuclein. This points to a distinct interaction between diphenyl-pyrazole and the fibrillar structure with a high binding affinity (K d = 190 ± 120 nM) for anle138b. Several α-synuclein proteins form a hydrophobic binding pocket for the diphenyl-pyrazole compound. A UV-induced dehalogenation reaction was observed for anle138b which is modulated by the hydrophobic environment of the fibrils. Conclusion: Fluorescence of the investigated diphenyl-pyrazole compounds strongly increases upon binding to fibrillar α-synuclein structures. Binding at high affinity occurs to hydrophobic pockets in the fibrils. General significance: The observed particular fluorescence properties of the diphenyl-pyrazole molecules open new possibilities for the investigation of the mode of action of these compounds in neurodegenerative diseases. The high binding affinity to aggregates and the strong increase in fluorescence upon binding make the compounds promising fluorescence markers for the analysis of aggregation-dependent epitopes.

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“…It has been reported that the species formed during the aggregation reactions have a toxic effect on cells 5, 6, 7, 8. Several possible mechanisms of cellular damage have been identified with relative contributions that depend on both the concentrations and the types of aggregates present 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11. The aggregation process that results in the formation of oligomers may contribute to cellular damage 12, 13, 14, 15.…”

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confidence: 99%

Ultrasensitive Measurement of Ca²⁺ Influx into Lipid Vesicles Induced by Protein Aggregates

Flagmeier

Wirthensohn

et al. 2017

Angew Chem Int Ed

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To quantify and characterize the potentially toxic protein aggregates associated with neurodegenerative diseases, a high‐throughput assay based on measuring the extent of aggregate‐induced Ca2+ entry into individual lipid vesicles has been developed. This approach was implemented by tethering vesicles containing a Ca2+ sensitive fluorescent dye to a passivated surface and measuring changes in the fluorescence as a result of membrane disruption using total internal reflection microscopy. Picomolar concentrations of Aβ42 oligomers could be observed to induce Ca2+ influx, which could be inhibited by the addition of a naturally occurring chaperone and a nanobody designed to bind to the Aβ peptide. We show that the assay can be used to study aggregates from other proteins, such as α‐synuclein, and to probe the effects of complex biofluids, such as cerebrospinal fluid, and thus has wide applicability.

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Toxic effects of amyloid fibrils on cell membranes: the importance of ganglioside GM1

Cited by 117 publications

References 69 publications

Direct three-dimensional visualization of membrane disruption by amyloid fibrils

Direct three-dimensional visualization of membrane disruption by amyloid fibrils

Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates

Ultrasensitive Measurement of Ca²⁺ Influx into Lipid Vesicles Induced by Protein Aggregates

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Toxic effects of amyloid fibrils on cell membranes: the importance of ganglioside GM1

Cited by 117 publications

References 69 publications

Direct three-dimensional visualization of membrane disruption by amyloid fibrils

Direct three-dimensional visualization of membrane disruption by amyloid fibrils

Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates

Ultrasensitive Measurement of Ca2+ Influx into Lipid Vesicles Induced by Protein Aggregates

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Ultrasensitive Measurement of Ca²⁺ Influx into Lipid Vesicles Induced by Protein Aggregates