α‐Synuclein Oligomers: A Study in Diversity

Diggelen, Femke van; Tepper, Armand W.J.W.; Apetri, Mihaela; Otzen, Daniel E.

doi:10.1002/ijch.201600116

Cited by 19 publications

(34 citation statements)

References 240 publications

(504 reference statements)

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“…Using sedimentation and gel filtration chromatography, the researchers identified spheres (range of heights: 2–6 nm), chains of spheres (protofibrils), and rings/annulars (heights: ~4 nm) from fibrils (~8 nm in diameter) by AFM. For a comprehensive account of αS oligomers and their in vitro preparation protocols, readers may refer to a recent review by van Diggelen et al 283 …”

Section: Alpha-synuclein and Parkinson’s Diseasementioning

confidence: 99%

Implications of peptide assemblies in amyloid diseases

et al. 2017

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Neurodegenerative disorders and type 2 diabetes are global epidemics compromising the quality of life of millions worldwide, with profound social and economic implications. Despite the significant differences in pathology – much of which are poorly understood – these diseases are commonly characterized by the presence of cross-β amyloid fibrils as well as the loss of neuronal or pancreatic β-cells. In this review, we document research progress on the molecular and mesoscopic self-assembly of amyloid-beta, alpha synuclein, human islet amyloid polypeptide and prions, the peptides and proteins associated with Alzheimer’s, Parkinson’s, type 2 diabetes and prions diseases. In addition, we discuss the toxicities of these amyloid proteins based on their self-assembly as well as their interactions with membranes, metal ions, small molecules and engineered nanoparticles. Through this presentation we show the remarkable similarities and differences in the structural transitions of the amyloid proteins through primary and secondary nucleation, the common evolution from disordered monomers to alpha-helices and then to β-sheets when the proteins encounter the cell membrane, and, the consensus (with a few exceptions) that off-pathway oligomers, rather than amyloid fibrils, are the toxic species regardless of the pathogenic protein sequence or physicochemical properties. In addition, we highlight the crucial role of molecular self-assembly in eliciting the biological and pathological consequences of the amyloid proteins within the context of their cellular environments and their spreading between cells and organs. Exploiting such structure-function-toxicity relationship may prove pivotal for the detection and mitigation of amyloid diseases.

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Section: Alpha-synuclein and Parkinson’s Diseasementioning

confidence: 99%

Implications of peptide assemblies in amyloid diseases

et al. 2017

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“…At present, pharmacological treatment is effective in the early stages of PD after diagnosis, but becomes inadequate as the disease progresses and new therapies are urgently needed . Aggregation of the presynaptic protein α‐synuclein (αSN) into oligomers (αSOs) is believed to play an important role in PD pathology and makes αSOs interesting therapeutic targets . However, there is no clear consensus on the molecular basis for toxicity, and a variety of toxic mechanisms have been proposed .…”

Section: Introductionmentioning

confidence: 99%

“…Aggregation of the presynaptic protein α‐synuclein (αSN) into oligomers (αSOs) is believed to play an important role in PD pathology and makes αSOs interesting therapeutic targets . However, there is no clear consensus on the molecular basis for toxicity, and a variety of toxic mechanisms have been proposed . These mechanisms include interactions with cellular components, such as membranes and synaptic proteins .…”

Section: Introductionmentioning

confidence: 99%

The interactome of stabilized α‐synuclein oligomers and neuronal proteins

et al. 2019

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While it is generally accepted that a-synuclein oligomers (aSOs) play an important role in neurodegeneration in Parkinson's disease, the basis for their cytotoxicity remains unclear. We have previously shown that docosahexaenoic acid (DHA) stabilizes aSOs against dissociation without compromising their ability to colocalize with glutamatergic synapses of primary hippocampal neurons, suggesting that they bind to synaptic proteins. Here, we develop a proteomic screen for putative aSO binding partners in rat primary neurons using DHA-stabilized human aSOs as a bait protein. The protocol involved co-immunoprecipitation in combination with a photoactivatable heterobifunctional sulfo-LC-SDA crosslinker which did not compromise neuronal binding and preserved the interaction between the aSOsbinding partners. We identify in total 29 proteins associated with DHA-aSO of which eleven are membrane proteins, including synaptobrevin-2B (VAMP-2B), the sodium-potassium pump (Na + /K + ATPase), the V-type ATPase, the voltage-dependent anion channel and calcium-/calmodulin-dependent protein kinase type II subunit gamma; only these five hits were also found in previous studies which used unmodified aSOs as bait. We also identified Rab-3A as a target with likely disease relevance. Three out of four selected hits were subsequently validated with dot-blot binding assays. In addition, likely binding sites on these ligands were identified by computational analysis, highlighting a diversity of possible interactions between aSOs and target proteins. These results constitute an important step in the search for disease-modifying treatments targeting toxic aSOs. AbbreviationsCo-IP, co-immunoprecipitation; LC-MS/MS, liquid chromatography coupled to mass spectrometric analysis and tandem mass spectrometry; NHS, N-hydroxysuccinimide; NMDA, N-methyl-D-aspartate; PD, Parkinson's disease; sulfo-LC-SDA, sulfo-linker carbon-succinimidyl-diazirine; aSOs, a-synuclein oligomers.Proteomic identification of aSN oligomer ligands F. van Diggelen et al.

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“…15 The shape, size, and conformation of various different oligomers, and their kinetics of formation, have been described in the literature, but a consensus on the most disease relevant species has not yet been reached. 15 Several groups have described the existence of two different types of oligomers on the pathway to fibril formation. 16−19 The earliest oligomers detectable in the pathway have been shown to be smaller and less compact than the subsequent ones.…”

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confidence: 99%

“…To date, it appears that no universal standard detection method for oligomer formation has been established. 15…”

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confidence: 99%

α-Synuclein–Confocal Nanoscanning (ASYN-CONA), a Bead-Based Assay for Detecting Early-Stage α-Synuclein Aggregation

et al. 2019

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α-Synuclein fibrils are considered a hallmark of Parkinson’s disease and other synucleinopathies. However, small oligomers that formed during the early stages of α-synuclein aggregation are thought to be the main toxic species causing disease. The formation of α-synuclein oligomers has proven difficult to follow, because of the heterogeneity and transient nature of the species formed. Here, a novel bead-based aggregation assay for monitoring the earliest stages of α-synuclein oligomerization, α-Synuclein–Confocal Nanoscanning (ASYN-CONA), is presented. The α-synuclein A91C single cysteine mutant is modified with a trifunctional chemical tag, which allows simultaneous fluorescent labeling with a green dye (tetramethylrhodamine, TMR) and attachment to microbeads. Beads with bound TMR-labeled α-synuclein are then incubated with a red dye (Cy5)-labeled variant of α-synuclein A91C, and EtOH (20%) to induce aggregation. Aggregation is detected by confocal scanning imaging, below the equatorial plane of the beads, which is known as the CONA technique. On-bead TMR-labeled α-synuclein and aggregated Cy5-labeled α-synuclein from the solution are quantitatively monitored in parallel by detection of fluorescent halos or “rings”. α-Synuclein on-bead oligomerization results in a linear increase of red bead ring fluorescence intensity over a period of 5 h. Total internal reflection fluorescence microscopy was performed on oligomers cleaved from the beads, and it revealed that (i) oligomers are sufficiently stable in solution to investigate their composition, consisting of 6 ± 1 monomer units, and (ii) oligomers containing a mean of 15 monomers bind Thioflavin-T. Various known inhibitors of α-synuclein aggregation were used to validate the ASYN-CONA assay for drug screening. Baicalein, curcumin, and rifampicin showed concentration-dependent inhibition of the α-synuclein aggregation and the IC50 (the concentration of the compound at which the maxiumum intensity was reduced by one-half) were calculated.

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α‐Synuclein Oligomers: A Study in Diversity

Cited by 19 publications

References 240 publications

Implications of peptide assemblies in amyloid diseases

Implications of peptide assemblies in amyloid diseases

The interactome of stabilized α‐synuclein oligomers and neuronal proteins

α-Synuclein–Confocal Nanoscanning (ASYN-CONA), a Bead-Based Assay for Detecting Early-Stage α-Synuclein Aggregation

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