Membrane interactions and fibrillization of α‐synuclein play an essential role in membrane disruption

Chaudhary, Himanshu; Stefanovic, A.; Subramaniam, Vinod; Claessens, Mireille Maria Anna Elisabeth

doi:10.1016/j.febslet.2014.10.016

Cited by 42 publications

(54 citation statements)

References 48 publications

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“…The addition of α-syn monomers to the PFFs at the cell surface promotes the formation of a complex fibrillar network that compromises the plasma membrane integrity, as shown by the higher uptake of vital dyes with massive cell death as a consequence. Our data are in line with recent studies showing that interaction and aggregation of α-syn with lipid bilayers or vesicles in vitro leads to membrane disintegration 52,57 and in vivo accumulation of extracellular α-syn at the surface of primary neurons perforates the plasma membrane leading to synaptic transmission defects and neuronal cell loss. 58 Interestingly, newly formed α-syn aggregates following the addition of α-syn mixture to the culture media were internalized into M17 cells more rapidly than pure PFFs.…”

Section: F(2 μM) M(18μm) + F(2μm)supporting

confidence: 92%

“…Fibrillar α-syn species, but not α-syn monomers, bind tightly to the plasma membrane and serve as nucleation sites for the aggregation of extracellular monomeric α-syn. The accumulation of these newly formed aggregates could induce toxicity through the disruption of the membrane induced by fibril growth on the membrane, leading to membrane thinning 61 and disruption through sequestration of lipid molecules 52,57 (Supplementary Figure S12A) or pore formation 62 (Supplementary Figure S12B). It has been also postulated that secondary nucleation events could contribute to cellular toxicity by promoting the formation of highly toxic oligomeric species, [54][55][56] although the mechanisms by which these species induce toxicity and whether or not they act directly on membrane receptors remain unknown (Supplementary Figure S12C1).…”

Section: F(2 μM) M(18μm) + F(2μm)mentioning

confidence: 99%

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Fibril growth and seeding capacity play key roles in α-synuclein-mediated apoptotic cell death

et al. 2015

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The role of extracellular α-synuclein (α-syn) in the initiation and the spreading of neurodegeneration in Parkinson's disease (PD) has been studied extensively over the past 10 years. However, the nature of the α-syn toxic species and the molecular mechanisms by which they may contribute to neuronal cell loss remain controversial. In this study, we show that fully characterized recombinant monomeric, fibrillar or stabilized forms of oligomeric α-syn do not trigger significant cell death when added individually to neuroblastoma cell lines. However, a mixture of preformed fibrils (PFFs) with monomeric α-syn becomes toxic under conditions that promote their growth and amyloid formation. In hippocampal primary neurons and ex vivo hippocampal slice cultures, α-syn PFFs are capable of inducing a moderate toxicity over time that is greatly exacerbated upon promoting fibril growth by addition of monomeric α-syn. The causal relationship between α-syn aggregation and cellular toxicity was further investigated by assessing the effect of inhibiting fibrillization on α-syn-induced cell death. Remarkably, our data show that blocking fibril growth by treatment with known pharmacological inhibitor of α-syn fibrillization (Tolcapone) or replacing monomeric α-syn by monomeric β-synuclein in α-syn mixture composition prevent α-syn-induced toxicity in both neuroblastoma cell lines and hippocampal primary neurons. We demonstrate that exogenously added α-syn fibrils bind to the plasma membrane and serve as nucleation sites for the formation of α-syn fibrils and promote the accumulation and internalization of these aggregates that in turn activate both the extrinsic and intrinsic apoptotic cell death pathways in our cellular models. Our results support the hypothesis that ongoing aggregation and fibrillization of extracellular α-syn play central roles in α-syn extracellular toxicity, and suggest that inhibiting fibril growth and seeding capacity constitute a viable strategy for protecting against α-syn-induced toxicity and slowing the progression of neurodegeneration in PD and other synucleinopathies. 1 Nevertheless, the relationship between α-syn aggregation and neurodegeneration in PD remains elusive. 2A possible role for extracellular α-syn in the pathogenicity of PD emerged from the observation that newly grafted neurons in PD patients exhibit α-syn pathology similar to that of neighboring diseased cells. 3,4 Despite the consensus that α-syn is mainly an intracellular protein, α-syn has been detected in the cerebrospinal fluid under both pathological and healthy conditions. 5 In addition, in vivo rodent models and cellular studies have shown that monomers 6 and aggregated forms 6,7 of α-syn are secreted into the extracellular space via several mechanisms, 7,8 including the nonclassical endoplasmic reticulum/Golgi-independent exocytosis 8 or the exosomal route, 9,10 and are then internalized by neighboring cells. 7This suggests that extracellular α-syn may play a critical role in the spreading of α-syn pathology throughout the brai...

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Section: F(2 μM) M(18μm) + F(2μm)supporting

confidence: 92%

Section: F(2 μM) M(18μm) + F(2μm)mentioning

confidence: 99%

Fibril growth and seeding capacity play key roles in α-synuclein-mediated apoptotic cell death

et al. 2015

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“…No clear correlation has been found between the amount of α-syn inclusions and the stage of PD (Chaudhary et al 2014), although larger areas of the brain contain aggregated α-syn as the disease progresses (Braak et al 2002).…”

Section: Discussionmentioning

confidence: 98%

Secondary nucleation of monomers on fibril surface dominatesα-synuclein aggregation and provides autocatalytic amyloid amplification

Gaspar

Meisl

Buell

et al. 2017

Quart. Rev. Biophys.

194

220

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Abstract. Parkinson's disease (PD) is characterized by proteinaceous aggregates named Lewy Bodies and Lewy Neurites containing α-synuclein fibrils. The underlying aggregation mechanism of this protein is dominated by a secondary process at mildly acidic pH, as in endosomes and other organelles. This effect manifests as a strong acceleration of the aggregation in the presence of seeds and a weak dependence of the aggregation rate on monomer concentration. The molecular mechanism underlying this process could be nucleation of monomers on fibril surfaces or fibril fragmentation. Here, we aim to distinguish between these mechanisms. The nature of the secondary processes was investigated using differential sedimentation analysis, trap and seed experiments, quartz crystal microbalance experiments and super-resolution microscopy. The results identify secondary nucleation of monomers on the fibril surface as the dominant secondary process leading to rapid generation of new aggregates, while no significant contribution from fragmentation was found. The newly generated oligomeric species quickly elongate to further serve as templates for secondary nucleation and this may have important implications in the spreading of PD.

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“…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. Some of these mechanisms are thought to involve specific binding to receptors on the cell membrane1, 5, 9 while others appear to be the consequence of non‐specific membrane disruption 1, 3, 5, 9, 16.…”

mentioning

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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Membrane interactions and fibrillization of α‐synuclein play an essential role in membrane disruption

Cited by 42 publications

References 48 publications

Fibril growth and seeding capacity play key roles in α-synuclein-mediated apoptotic cell death

Fibril growth and seeding capacity play key roles in α-synuclein-mediated apoptotic cell death

Secondary nucleation of monomers on fibril surface dominatesα-synuclein aggregation and provides autocatalytic amyloid amplification

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

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Membrane interactions and fibrillization of α‐synuclein play an essential role in membrane disruption

Cited by 42 publications

References 48 publications

Fibril growth and seeding capacity play key roles in α-synuclein-mediated apoptotic cell death

Fibril growth and seeding capacity play key roles in α-synuclein-mediated apoptotic cell death

Secondary nucleation of monomers on fibril surface dominatesα-synuclein aggregation and provides autocatalytic amyloid amplification

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