Fibril Fragmentation Enhances Amyloid Cytotoxicity

Xue, Wei‐Feng; Hellewell, Andrew L.; Gosal, Walraj S.; Homans, Steve W.; Hewitt, Eric W.; Radford, Sheena E.

doi:10.1074/jbc.m109.049809

Cited by 346 publications

(469 citation statements)

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“…Because these are known to be reactive sites, the above observations suggest a role for fibril ends in amyloid-lipid interaction and possibly in amyloid pathogenesis (23,24,27). Fragmented fibrils of all three proteins were also found to induce dye leakage from negatively charged liposomes, the most susceptible of which contain a mixture of the cellular lipids phosphatidylcholine (PC) and phosphatidylglycerol (PG), but liposomes with a variety of compositions were damaged by the fibrils in all cases (27).Here, we use β 2 m amyloid fibrils formed in vitro as a model system to investigate the structural basis of membrane damage by amyloid fibrils (27, 28). Previous studies have shown that these fibrils possess a parallel in register cross-β structure (29, 30) assembled into multidomain filaments coiled together, described by cryo-EM (28).…”

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confidence: 99%

“…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 elongation of amyloid fibril growth (25, 26). Recently, Xue et al (27) showed that short fibrils of β 2 -microglobulin (β 2 m), α-synuclein, and hen lysozyme, each prepared by fragmentation of longer fibrils, cause increased damage to membranes and disruption to cellular function compared with the initial long fibrils. Short and long fibril preparations differ in the number of fibril ends at a given protein concentration.…”

mentioning

confidence: 99%

“…Here, we use β 2 m amyloid fibrils formed in vitro as a model system to investigate the structural basis of membrane damage by amyloid fibrils (27,28). Previous studies have shown that these fibrils possess a parallel in register cross-β structure (29,30) assembled into multidomain filaments coiled together, described by cryo-EM (28).…”

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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.

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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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confidence: 99%

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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.

Self Cite

169

177

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“…2 At the same time, different fibril morphologies can result in different degrees of toxicity 3 and fibril fragmentation can enhance amyloid cytotoxicity. 4 Thus, detailed knowledge about the structure of amyloid fibrils is required to obtain insight into the toxicity of protein aggregates.…”

Section: Introductionmentioning

confidence: 99%

Determination of amyloid core structure using chemical shifts

Skora

Zweckstetter

2012

Protein Science

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Amyloid fibrils are the pathological hallmark of a large variety of neurodegenerative disorders. The structural characterization of amyloid fibrils, however, is challenging due to their non-crystalline, heterogeneous, and often dynamic nature. Thus, the structure of amyloid fibrils of many proteins is still unknown. We here show that the structure calculation program CS-Rosetta can be used to obtain insight into the core structure of amyloid fibrils. Driven by experimental solid-state NMR chemical shifts and taking into account the polymeric nature of fibrils CS-Rosetta allows modeling of the core of amyloid fibrils. Application to the Y145X stop mutant of the human prion protein reveals a left-handed b-helix.

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“…Stirring and shaking protein samples during aggregation can affect amyloid fibril formation and change the properties of the resulting aggregated species [13]. Therefore, we next examined the aggregation properties of Arctic and Rescue under conditions in which the samples were shaken.…”

Section: Characterization Of the Aggregation Process For Arctic And Rmentioning

confidence: 99%

Identification of distinct physiochemical properties of toxic prefibrillar species formed by Aβ peptide variants

Göransson

Nilsson

Kågedal

et al. 2012

Biochemical and Biophysical Research Communications

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The formation of amyloid-β peptide (Aβ) aggregates at an early stage during the selfassembly process is an important factor in the development of Alzheimer's disease. The toxic effect is believed to be exerted by prefibrillar species of Aβ. It is therefore important to identify which prefibrillar species are toxic and characterize their distinct properties. In the present study, we investigated the in vitro aggregation behavior of Aβ-derived peptides possessing different levels of neurotoxic activity, using fluorescence spectroscopy in combination with transmission electron microscopy. The toxicity of various Aβ aggregates was assessed by using cultures of human neuroblastoma cells. Through combined use of the fluorescence probe 8-anilino-1-napthalenesulfonate (ANS) and the novel luminescent probe pentamer formyl thiophene acetic acid (p-FTAA), we were able to identify those Aβ peptidederived prefibrillar species which exhibited cellular toxicity. In particular, species, which formed early during the aggregation process and showed strong p-FTAA and ANS fluorescence, were the species that possessed toxic activities. Moreover, by manipulating the aggregation conditions, it was possible to change the capacity of the Aβ peptide to form nontoxic versus toxic species.

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Fibril Fragmentation Enhances Amyloid Cytotoxicity

Cited by 346 publications

References 47 publications

Direct three-dimensional visualization of membrane disruption by amyloid fibrils

Direct three-dimensional visualization of membrane disruption by amyloid fibrils

Determination of amyloid core structure using chemical shifts

Identification of distinct physiochemical properties of toxic prefibrillar species formed by Aβ peptide variants

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