scholarly journals Functional amyloids in the microbiomes of a rat Parkinson's disease model and wild-type rats

2021 ◽  
Author(s):  
Line F Christensen ◽  
Saeid H Alijanvand ◽  
Michał Burdukiewicz ◽  
Florian Alexander Herbst ◽  
Henrik Kjeldal ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Formic Acid ◽  
Proteinase K ◽  
Amyloid Formation ◽  
Wild Type ◽  
Amyloid Proteins ◽  
Fecal Matter ◽  
Functional Amyloid

Cross-seeding between amyloidogenic proteins in the gut is receiving increasing attention as a possible mechanism for initiation or acceleration of amyloid formation by aggregation-prone proteins such as αSN, which is central in the development of Parkinson's disease. This is particularly pertinent in view of the growing number of functional (i.e. benign and useful) amyloid proteins discovered in bacteria. Here we identify two functional amyloid proteins, Pr12 and Pr17, in fecal matter from Parkinson's disease transgenic rats and their wild type counterparts, based on their stability against dissolution by formic acid. Both proteins show robust aggregation into ThT-positive aggregates that contain higher-order b-sheets and have a fibrillar morphology, indicative of amyloid proteins. In addition, Pr17 aggregates formed in vitro showed significant resistance against formic acid, suggesting an ability to form highly stable amyloid. Treatment with proteinase K revealed a protected core of approx. 9 kDa. Neither Pr12 nor Pr17, however, affected αSN aggregation in vitro. Thus, amyloidogenicity does not per se lead to an ability to cross-seed fibrillation of αSN. Our results support the use of proteomics and formic acid to identify amyloid protein in complex mixtures and indicates the existence of numerous functional amyloid proteins in microbiomes.

scholarly journals Familial Parkinson's Disease Mutant E46K α-Synuclein Localizes to Membranous Structures, Forms Aggregates, and Induces Toxicity in Yeast Models

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Michael Fiske ◽  
Michael White ◽  
Stephanie Valtierra ◽  
Sara Herrera ◽  
Keith Solvang ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Plasma Membrane ◽  
Mutant Form ◽  
Phospholipid Membrane ◽  
Endomembrane System ◽  
Wild Type ◽  
Significant Toxicity ◽  
Familial Parkinson’S Disease

In Parkinson’s disease (PD), midbrain dopaminergic neuronal death is linked to the accumulation of aggregated α-synuclein. The familial PD mutant form of α-synuclein, E46K, has not been thoroughly evaluated yet in an organismal model system. Here, we report that E46K resembled wild-type (WT) α-synuclein in Saccharomyces cerevisiae in that it predominantly localized to the plasma membrane, and it did not induce significant toxicity or accumulation. In contrast, in Schizosaccharomyces pombe, E46K did not associate with the plasma membrane. Instead, in one strain, it extensively aggregated in the cytoplasm and was as toxic as WT. Remarkably, in another strain, E46K extensively associated with the endomembrane system and was more toxic than WT. Our studies recapitulate and extend aggregation and phospholipid membrane association properties of E46K previously observed in vitro and cell culture. Furthermore, it supports the notion that E46K generates toxicity partly due to increased association with endomembrane systems within cells.

scholarly journals Alpha-synuclein stepwise aggregation reveals features of an early onset mutation in Parkinson’s disease

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Guilherme A. P. de Oliveira ◽  
Jerson L. Silva
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Early Onset ◽  
Point Mutations ◽  
Alpha Synuclein ◽  
Amyloid Formation ◽  
Wild Type ◽  
Cryo Electron Microscopy ◽  
Familial Parkinson’S Disease ◽  
Direct Detector

Abstract Amyloid formation is a process involving interconverting protein species and results in toxic oligomers and fibrils. Aggregated alpha-synuclein (αS) participates in neurodegenerative maladies, but a closer understanding of the early αS polymerization stages and polymorphism of heritable αS variants is sparse still. Here, we distinguished αS oligomer and protofibril interconversions in Thioflavin T polymerization reactions. The results support a hypothesis reconciling the nucleation-polymerization and nucleation-conversion-polymerization models to explain the dissimilar behaviors of wild-type and the A53T mutant. Cryo-electron microscopy with a direct detector shows the polymorphic nature of αS fibrils formed by heritable A30P, E46K, and A53T point mutations. By showing that A53T rapidly nucleates competent species, continuously elongates fibrils in the presence of increasing amounts of seeds, and overcomes wild-type surface requirements for growth, our findings place A53T with features that may explain the early onset of familial Parkinson’s disease cases bearing this mutation.

scholarly journals The G2385R risk factor for Parkinson's disease enhances CHIP-dependent intracellular degradation of LRRK2

2017 ◽  
Vol 474 (9) ◽  
pp. 1547-1558 ◽  
Author(s):  
Iakov N. Rudenko ◽  
Alice Kaganovich ◽  
Rebekah G. Langston ◽  
Aleksandra Beilina ◽  
Kelechi Ndukwe ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Risk Factor ◽  
Steady State ◽  
Proteasomal Degradation ◽  
Wild Type ◽  
Intracellular Protein ◽  
Protein Levels ◽  
Intracellular Degradation

Autosomal dominant mutations in leucine-rich repeat kinase 2 (LRRK2) are associated with Parkinson's disease (PD). Most pathogenic LRRK2 mutations result in amino acid substitutions in the central ROC (Ras of complex proteins)–C-terminus of ROC–kinase triple domain and affect enzymatic functions of the protein. However, there are several variants in LRRK2, including the risk factor G2385R, that affect PD pathogenesis by unknown mechanisms. Previously, we have shown that G2385R LRRK2 has decreased kinase activity in vitro and altered affinity to LRRK2 interactors. Specifically, we found an increased binding to the chaperone Hsp90 (heat shock protein 90 kDa) that is known to stabilize LRRK2, suggesting that G2385R may have structural effects on LRRK2. In the present study, we further explored the effects of G2385R on LRRK2 in cells. We found that G2385R LRRK2 has lower steady-state intracellular protein levels compared with wild-type LRRK2 due to increased protein turnover of the mutant protein. Mechanistically, this is a consequence of a higher affinity of G2385R compared with the wild-type protein for two proteins involved in proteasomal degradation, Hsc70 and carboxyl-terminus of Hsc70-interacting protein (CHIP). Overexpression of CHIP decreased intracellular protein levels of both G2385R mutant and wild-type LRRK2, while short interfering RNA CHIP knockdown had the opposite effect. We suggest that the G2385R substitution tilts the equilibrium between refolding and proteasomal degradation toward intracellular degradation. The observation of lower steady-state protein levels may explain why G2385R is a risk factor rather than a penetrant variant for inherited PD.

scholarly journals Effects of the Toxic Metals Arsenite and Cadmium on α-Synuclein Aggregation In Vitro and in Cells

2021 ◽  
Vol 22 (21) ◽  
pp. 11455
Author(s):  
Emma Lorentzon ◽  
Istvan Horvath ◽  
Ranjeet Kumar ◽  
Joana Isabel Rodrigues ◽  
Markus J. Tamás ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Yeast Cells ◽  
Amyloid Formation ◽  
Amyloid Fibers ◽  
Force Microscopy ◽  
Atomic Force ◽  
In Vitro Characterization ◽  
Underlying Mechanisms

Exposure to heavy metals, including arsenic and cadmium, is associated with neurodegenerative disorders such as Parkinson’s disease. However, the mechanistic details of how these metals contribute to pathogenesis are not well understood. To search for underlying mechanisms involving α-synuclein, the protein that forms amyloids in Parkinson’s disease, we here assessed the effects of arsenic and cadmium on α-synuclein amyloid formation in vitro and in Saccharomyces cerevisiae (budding yeast) cells. Atomic force microscopy experiments with acetylated human α-synuclein demonstrated that amyloid fibers formed in the presence of the metals have a different fiber pitch compared to those formed without metals. Both metal ions become incorporated into the amyloid fibers, and cadmium also accelerated the nucleation step in the amyloid formation process, likely via binding to intermediate species. Fluorescence microscopy analyses of yeast cells expressing fluorescently tagged α-synuclein demonstrated that arsenic and cadmium affected the distribution of α-synuclein aggregates within the cells, reduced aggregate clearance, and aggravated α-synuclein toxicity. Taken together, our in vitro data demonstrate that interactions between these two metals and α-synuclein modulate the resulting amyloid fiber structures, which, in turn, might relate to the observed effects in the yeast cells. Whilst our study advances our understanding of how these metals affect α-synuclein biophysics, further in vitro characterization as well as human cell studies are desired to fully appreciate their role in the progression of Parkinson’s disease.

Potential treatment of Parkinson’s disease using new-generation carbon nanotubes: a biomolecular in silico study

Nanomedicine ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. 189-204
Author(s):  
Ehsan Alimohammadi ◽  
Arash Nikzad ◽  
Mohammad Khedri ◽  
Milad Rezaian ◽  
Ahmad Miri Jahromi ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Lewy Bodies ◽  
Inhibitory Effect ◽  
Strong Interactions ◽  
Amyloid Formation ◽  
Potential Treatment ◽  
Phosphorus Doped

Background: One of the underlying mechanisms of Parkinson’s disease is the aggregation of α-synuclein proteins, including amyloids and Lewy bodies in the brain. Aim: To study the inhibitory effect of doped carbon nanotubes (CNTs) on amyloid aggregation. Materials & methods: Molecular dynamics tools were utilized to simulate the influence of CNTs doped with phosphorus, nitrogen and bromine and nitrogen on the formation of α-synuclein amyloid. Results: The CNTs exhibited strong interactions with α-synuclein, with phosphorus-doped CNTs having the most substantial interactions. Conclusion: Doped-CNTs, especially phosphorus-doped carbon nanotube could effectively prevent α-synuclein amyloid formation, thus, it could be considered as a potential treatment for Parkinson’s disease. However, further in vitro and clinical investigations are required.

scholarly journals Parkinson’s disease recovery by GM1 oligosaccharide treatment in the B4galnt1+/− mouse model

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Elena Chiricozzi ◽  
Laura Mauri ◽  
Giulia Lunghi ◽  
Erika Di Biase ◽  
Maria Fazzari ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Therapeutic Potential ◽  
Physical Symptoms ◽  
Wild Type ◽  
Ganglioside Content ◽  
Sporadic Parkinson’S Disease ◽  
Specific Membrane ◽  
The Brain

AbstractGiven the recent in vitro discovery that the free soluble oligosaccharide of GM1 is the bioactive portion of GM1 for neurotrophic functions, we investigated its therapeutic potential in the B4galnt1+/− mice, a model of sporadic Parkinson’s disease. We found that the GM1 oligosaccharide, systemically administered, reaches the brain and completely rescues the physical symptoms, reduces the abnormal nigral α-synuclein content, restores nigral tyrosine hydroxylase expression and striatal neurotransmitter levels, overlapping the wild-type condition. Thus, this study supports the idea that the Parkinson’s phenotype expressed by the B4galnt1+/− mice is due to a reduced level of neuronal ganglioside content and lack of interactions between the oligosaccharide portion of GM1 with specific membrane proteins. It also points to the therapeutic potential of the GM1 oligosaccharide for treatment of sporadic Parkinson’s disease.

scholarly journals The α-synuclein hereditary mutation E46K unlocks a more stable, pathogenic fibril structure

2020 ◽  
Vol 117 (7) ◽  
pp. 3592-3602 ◽  
Author(s):  
David R. Boyer ◽  
Binsen Li ◽  
Chuanqi Sun ◽  
Weijia Fan ◽  
Kang Zhou ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Lewy Body ◽  
Lewy Body Dementia ◽  
Salt Bridge ◽  
Wild Type ◽  
Molecular Feature ◽  
Multiple Systems ◽  
Fibril Structure

Aggregation of α-synuclein is a defining molecular feature of Parkinson’s disease, Lewy body dementia, and multiple systems atrophy. Hereditary mutations in α-synuclein are linked to both Parkinson’s disease and Lewy body dementia; in particular, patients bearing the E46K disease mutation manifest a clinical picture of parkinsonism and Lewy body dementia, and E46K creates more pathogenic fibrils in vitro. Understanding the effect of these hereditary mutations on α-synuclein fibril structure is fundamental to α-synuclein biology. We therefore determined the cryo-electron microscopy (cryo-EM) structure of α-synuclein fibrils containing the hereditary E46K mutation. The 2.5-Å structure reveals a symmetric double protofilament in which the molecules adopt a vastly rearranged, lower energy fold compared to wild-type fibrils. We propose that the E46K misfolding pathway avoids electrostatic repulsion between K46 and K80, a residue pair which form the E46-K80 salt bridge in the wild-type fibril structure. We hypothesize that, under our conditions, the wild-type fold does not reach this deeper energy well of the E46K fold because the E46-K80 salt bridge diverts α-synuclein into a kinetic trap—a shallower, more accessible energy minimum. The E46K mutation apparently unlocks a more stable and pathogenic fibril structure.

scholarly journals Pharmacological inhibition of nSMase2 reduces brain exosome release and α-synuclein pathology in a Parkinson’s disease model

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Chunni Zhu ◽  
Tina Bilousova ◽  
Samantha Focht ◽  
Michael Jun ◽  
Chris Jean Elias ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Neurodegenerative Diseases ◽  
Motor Function ◽  
Cell Model ◽  
Extracellular Vesicle ◽  
Alpha Synuclein ◽  
Proteinase K ◽  
In Vivo Studies

Abstract Aim We have previously reported that cambinol (DDL-112), a known inhibitor of neutral sphingomyelinase-2 (nSMase2), suppressed extracellular vesicle (EV)/exosome production in vitro in a cell model and reduced tau seed propagation. The enzyme nSMase2 is involved in the production of exosomes carrying proteopathic seeds and could contribute to cell-to-cell transmission of pathological protein aggregates implicated in neurodegenerative diseases such as Parkinson’s disease (PD). Here, we performed in vivo studies to determine if DDL-112 can reduce brain EV/exosome production and proteopathic alpha synuclein (αSyn) spread in a PD mouse model. Methods The acute effects of single-dose treatment with DDL-112 on interleukin-1β-induced extracellular vesicle (EV) release in brain tissue of Thy1-αSyn PD model mice and chronic effects of 5 week DDL-112 treatment on behavioral/motor function and proteinase K-resistant αSyn aggregates in the PD model were determined. Results/discussion In the acute study, pre-treatment with DDL-112 reduced EV/exosome biogenesis and in the chronic study, treatment with DDL-112 was associated with a reduction in αSyn aggregates in the substantia nigra and improvement in motor function. Inhibition of nSMase2 thus offers a new approach to therapeutic development for neurodegenerative diseases with the potential to reduce the spread of disease-specific proteopathic proteins.

scholarly journals Defining an amyloid link Between Parkinson’s disease and melanoma

2020 ◽  
Vol 117 (37) ◽  
pp. 22671-22673 ◽  
Author(s):  
Dexter N. Dean ◽  
Jennifer C. Lee
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Protein A ◽  
Fibril Formation ◽  
Human Melanoma ◽  
Melanin Content ◽  
Functional Amyloid ◽  
Multiple Generations ◽  
Repeat Domain

An epidemiological connection exists between Parkinson’s disease (PD) and melanoma. α-Synuclein (α-syn), the hallmark pathological amyloid observed in PD, is also elevated in melanoma, where its expression is inversely correlated with melanin content. We present a hypothesis that there is an amyloid link between α-syn and Pmel17 (premelanosomal protein), a functional amyloid that promotes melanogenesis. Using SK-MEL 28 human melanoma cells, we show that endogenous α-syn is present in melanosomes, the organelle where melanin polymerization occurs. Using in vitro cross-seeding experiments, we show that α-syn fibrils stimulate the aggregation of a Pmel17 fragment constituting the repeat domain (RPT), an amyloidogenic domain essential for fibril formation in melanosomes. The cross-seeded fibrils exhibited α-syn−like ultrastructural features that could be faithfully propagated over multiple generations. This cross-seeding was unidirectional, as RPT fibrils did not influence α-syn aggregation. These results support our hypothesis that α-syn, a pathogenic amyloid, modulates Pmel17 aggregation in the melanosome, defining a molecular link between PD and melanoma.

scholarly journals Observation of an α-synuclein liquid droplet state and its maturation into Lewy body-like assemblies

2020 ◽  
Author(s):  
Maarten C. Hardenberg ◽  
Tessa Sinnige ◽  
Sam Casford ◽  
Samuel Dada ◽  
Chetan Poudel ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Lewy Body ◽  
Amyloid Fibrils ◽  
Liquid Droplet ◽  
Large Body ◽  
Lewy Bodies ◽  
Amyloid Formation ◽  
C Elegans

AbstractMisfolded α-synuclein is a major component of Lewy bodies, which are a hallmark of Parkinson’s disease. A large body of evidence shows that α-synuclein can self-assemble into amyloid fibrils, but the relationship between amyloid formation and Lewy body formation still remains unclear. Here we show, both in vitro and in a C. elegans model of Parkinson’s disease, that α-synuclein undergoes liquid-liquid phase separation by forming a liquid droplet state, which converts into an amyloid-rich hydrogel. This maturation process towards the amyloid state is delayed in the presence of model synaptic vesicles in vitro. Taken together, these results suggest that the formation of Lewy bodies is linked to the arrested maturation of α-synuclein condensates in the presence of lipids and other cellular components.

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