scholarly journals Brazilin Removes Toxic alpha-Synuclein and Seeding Competent Assemblies from Parkinson Brain by Altering Conformational Equilibrium

2020 ◽  
Author(s):  
George R. Nahass ◽  
Yuanzi Sun ◽  
Yong Xu ◽  
Mark Batchelor ◽  
Madeleine Reilly ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Amyloid Fibrils ◽  
Disease Patient ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Major Constituent ◽  
List Type ◽  
Natural Polyphenol ◽  
Β Sheet

ABSTRACTAlpha-synuclein (α-syn) fibrils, a major constituent of the neurotoxic Lewy Bodies in Parkinson’s disease, form via nucleation dependent polymerization and can replicate by a seeding mechanism. Brazilin, a small molecule derived from red cedarwood trees in Brazil, has been shown to inhibit the fibrillogenesis of amyloid-beta (Aβ) and α-syn, prompting our inquiry in its mechanism of action. Here we test the effects of Brazilin on both seeded and unseeded α-syn fibril formation and show that the natural polyphenol inhibits fibrillogenesis of α-syn by a unique mechanism that is distinct from other polyphenols and is also distinct from its effect on Aβ. Brazilin preserves the natively unfolded state of α-syn by stabilizing the compact conformation of the α-syn monomer over the aggregation-competent extended conformation. Molecular docking of Brazilin shows the molecule to interact both with unfolded α-syn monomers and with the cross-β sheet structure of α-syn fibrils. Brazilin eliminates seeding competence of α-syn assemblies from Parkinson’s disease patient brain tissue, and treatment of pre-formed fibril assemblies with Brazilin significantly reduces their toxicity in primary neurons. Our findings suggest that Brazilin has substantial potential as a neuroprotective and therapeutic agent for Parkinson’s Disease.Highlights- The natural polyphenol Brazilin binds to monomeric, oligomeric and fibrillar α-syn- Brazilin shifts the equilibrium away from aggregation-competent monomer conformations- Brazilin inactivates seeding-competent α-syn isolated from Parkinson patients’ brains- Brazilin detoxifies α-syn aggregation intermediates and stabilizes mature amyloid fibrilsGraphical Abstract

scholarly journals Parkinson’s disease is a type of amyloidosis featuring accumulation of amyloid fibrils of α-synuclein

2019 ◽  
Vol 116 (36) ◽  
pp. 17963-17969 ◽  
Author(s):  
Katsuya Araki ◽  
Naoto Yagi ◽  
Koki Aoyama ◽  
Chi-Jing Choong ◽  
Hideki Hayakawa ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Amyloid Fibrils ◽  
Lewy Bodies ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
X Ray ◽  
Β Sheet ◽  
The Brain

Many neurodegenerative diseases are characterized by the accumulation of abnormal protein aggregates in the brain. In Parkinson’s disease (PD), α-synuclein (α-syn) forms such aggregates called Lewy bodies (LBs). Recently, it has been reported that aggregates of α-syn with a cross-β structure are capable of propagating within the brain in a prionlike manner. However, the presence of cross-β sheet-rich aggregates in LBs has not been experimentally demonstrated so far. Here, we examined LBs in thin sections of autopsy brains of patients with PD using microbeam X-ray diffraction (XRD) and found that some of them gave a diffraction pattern typical of a cross-β structure. This result confirms that LBs in the brain of PD patients contain amyloid fibrils with a cross-β structure and supports the validity of in vitro propagation experiments using artificially formed amyloid fibrils of α-syn. Notably, our finding supports the concept that PD is a type of amyloidosis, a disease featuring the accumulation of amyloid fibrils of α-syn.

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

2021 ◽  
Author(s):  
Maarten C Hardenberg ◽  
Tessa Sinnige ◽  
Sam Casford ◽  
Samuel Dada ◽  
Chetan Poudel ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Self Assembly ◽  
Lewy Body ◽  
Amyloid Fibrils ◽  
Liquid Droplet ◽  
Large Body ◽  
Lewy Bodies ◽  
Cellular Components

Abstract Misfolded 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 aggregate into amyloid fibrils, but the relationship between α-synuclein self-assembly and Lewy body formation remains unclear. Here we show, both in vitro and in a Caenorhabditis 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 with Lewy-body-like properties. 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 may be linked to the arrested maturation of α-synuclein condensates in the presence of lipids and other cellular components.

scholarly journals Subcellular orchestration of alpha-synuclein variants in Parkinson’s disease brains revealed by 3D multicolor STED microscopy

2018 ◽  
Author(s):  
Tim E. Moors ◽  
Christina A. Maat ◽  
Daniel Niedieker ◽  
Daniel Mona ◽  
Dennis Petersen ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Lewy Bodies ◽  
Distribution Patterns ◽  
Alpha Synuclein ◽  
Label Free ◽  
Post Translational Modifications ◽  
Sted Microscopy ◽  
C Terminus

AbstractPost-translational modifications of alpha-synuclein (aSyn), particularly phosphorylation at Serine 129 (Ser129-p) and truncation of its C-terminus (CTT), have been implicated in Parkinson’s disease (PD) pathology. To gain more insight in the relevance of Ser129-p and CTT aSyn under physiological and pathological conditions, we investigated their subcellular distribution patterns in normal aged and PD brains using highly-selective antibodies in combination with 3D multicolor STED microscopy. We show that CTT aSyn localizes in mitochondria in PD patients and controls, whereas the organization of Ser129-p in a cytoplasmic network is strongly associated with pathology. Nigral Lewy bodies show an onion skin-like architecture, with a structured framework of Ser129-p aSyn and neurofilaments encapsulating CTT aSyn in their core, which displayed high content of proteins and lipids by label-free CARS microscopy. The subcellular phenotypes of antibody-labeled pathology identified in this study provide evidence for a crucial role of Ser129-p aSyn in Lewy body formation.

scholarly journals Cryo-EM structure of alpha-synuclein fibrils

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Ricardo Guerrero-Ferreira ◽  
Nicholas MI Taylor ◽  
Daniel Mona ◽  
Philippe Ringler ◽  
Matthias E Lauer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Diagnosis And Treatment ◽  
Lewy Neurites ◽  
Cryo Electron Microscopy ◽  
High Concentrations ◽  
Hydrophobic Cleft

Parkinson’s disease is a progressive neuropathological disorder that belongs to the class of synucleinopathies, in which the protein alpha-synuclein is found at abnormally high concentrations in affected neurons. Its hallmark are intracellular inclusions called Lewy bodies and Lewy neurites. We here report the structure of cytotoxic alpha-synuclein fibrils (residues 1–121), determined by cryo-electron microscopy at a resolution of 3.4 Å. Two protofilaments form a polar fibril composed of staggered β-strands. The backbone of residues 38 to 95, including the fibril core and the non-amyloid component region, are well resolved in the EM map. Residues 50–57, containing three of the mutation sites associated with familial synucleinopathies, form the interface between the two protofilaments and contribute to fibril stability. A hydrophobic cleft at one end of the fibril may have implications for fibril elongation, and invites for the design of molecules for diagnosis and treatment of synucleinopathies.

What Is Known about the Cause

2013 ◽  
Author(s):  
J. Eric Ahlskog
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Medical Center ◽  
Single Gene ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Early Years ◽  
Gene Coding ◽  
Sporadic Parkinson’S Disease ◽  
High Concentrations

Most of the research into the cause of Lewy disorders has focused on Parkinson’s disease, since that is the best defined of these conditions and, therefore, the most straightforward to study. Dementia with Lewy bodies (DLB) is more difficult to diagnose with certainty, especially in the early years of the disease. What we collectively learn about Parkinson’s disease will likely be very relevant to our understanding of DLB. Multiple investigations have linked Parkinson’s disease to both environmental exposures and genetic factors. However, these associations have all been modest, and none of them accounts for more than a few percent of the contribution to the cause of sporadic Parkinson’s disease (i.e., the attributable risks are low). These investigations are ongoing and hopefully will soon provide a more complete understanding of the cause(s). Perhaps the most important clue to all Lewy conditions is located in the brain: the Lewy body itself. A recent sophisticated analysis of Lewy bodies revealed approximately 300 different component proteins. However, we already knew that Lewy bodies contain high concentrations of a normal protein called alpha synuclein. In fact, Lewy bodies are conventionally identified under the microscope with antibody stains that specifically bind to alpha synuclein. Could this be the crucial protein among the nearly 300? While the alpha synuclein story is focused on Parkinson’s disease, it may be just as relevant to DLB, as we shall see. The story starts with a large Italian-American family with Parkinson’s disease, studied by Dr. Lawrence Golbe and colleagues at the Robert Wood Johnson Medical Center in New Brunswick, New Jersey. In this rare family, many members of multiple generations had been affected by Parkinson’s disease (with Lewy bodies), consistent with a single gene passed on with dominant inheritance. It took a number of years to identify that abnormal gene, which ultimately was proven to be the gene coding for alpha synuclein. It was quickly discovered that this genetic error is not present in usual cases of Parkinson’s disease.

scholarly journals Parkinson’s disease-related phosphorylation at Tyr39 rearranges α-synuclein amyloid fibril structure revealed by cryo-EM

2020 ◽  
Vol 117 (33) ◽  
pp. 20305-20315 ◽  
Author(s):  
Kun Zhao ◽  
Yeh-Jun Lim ◽  
Zhenying Liu ◽  
Houfang Long ◽  
Yunpeng Sun ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Posttranslational Modifications ◽  
Cortical Neurons ◽  
Amyloid Fibrils ◽  
Lewy Bodies ◽  
Interaction Network ◽  
Lewy Neurites ◽  
Cryo Electron Microscopy ◽  
Fibril Structure

Posttranslational modifications (PTMs) of α-synuclein (α-syn), e.g., phosphorylation, play an important role in modulating α-syn pathology in Parkinson’s disease (PD) and α-synucleinopathies. Accumulation of phosphorylated α-syn fibrils in Lewy bodies and Lewy neurites is the histological hallmark of these diseases. However, it is unclear how phosphorylation relates to α-syn pathology. Here, by combining chemical synthesis and bacterial expression, we obtained homogeneous α-syn fibrils with site-specific phosphorylation at Y39, which exhibits enhanced neuronal pathology in rat primary cortical neurons. We determined the cryo-electron microscopy (cryo-EM) structure of the pY39 α-syn fibril, which reveals a fold of α-syn with pY39 in the center of the fibril core forming an electrostatic interaction network with eight charged residues in the N-terminal region of α-syn. This structure composed of residues 1 to 100 represents the largest α-syn fibril core determined so far. This work provides structural understanding on the pathology of the pY39 α-syn fibril and highlights the importance of PTMs in defining the polymorphism and pathology of amyloid fibrils in neurodegenerative diseases.

scholarly journals Cytotoxicity and Mitochondrial Dysregulation Caused by α-Synuclein in Dictyostelium discoideum

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2289 ◽  
Author(s):  
Sanjanie Fernando ◽  
Claire Y. Allan ◽  
Katelyn Mroczek ◽  
Xavier Pearce ◽  
Oana Sanislav ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Dictyostelium Discoideum ◽  
Mitochondrial Function ◽  
Molecular Mechanisms ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Cell Cortex ◽  
Mutant Proteins ◽  
C Terminus

Alpha synuclein has been linked to both sporadic and familial forms of Parkinson’s disease (PD) and is the most abundant protein in Lewy bodies a hallmark of Parkinson’s disease. The function of this protein and the molecular mechanisms underlying its toxicity are still unclear, but many studies have suggested that the mechanism of α-synuclein toxicity involves alterations to mitochondrial function. Here we expressed human α-synuclein and two PD-causing α-synuclein mutant proteins (with a point mutation, A53T, and a C-terminal 20 amino acid truncation) in the eukaryotic model Dictyostelium discoideum. Mitochondrial disease has been well studied in D. discoideum and, unlike in mammals, mitochondrial dysfunction results in a clear set of defective phenotypes. These defective phenotypes are caused by the chronic hyperactivation of the cellular energy sensor, AMP-activated protein kinase (AMPK). Expression of α-synuclein wild type and mutant forms was toxic to the cells and mitochondrial function was dysregulated. Some but not all of the defective phenotypes could be rescued by down regulation of AMPK revealing both AMPK-dependent and -independent mechanisms. Importantly, we also show that the C-terminus of α-synuclein is required and sufficient for the localisation of the protein to the cell cortex in D. discoideum.

scholarly journals Blood Plasma of Patients with Parkinson’s Disease Increases Alpha-Synuclein Aggregation and Neurotoxicity

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Peng Wang ◽  
Xin Li ◽  
Xuran Li ◽  
Weiwei Yang ◽  
Shun Yu
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Alternative Pathway ◽  
Lewy Bodies ◽  
Normal Subjects ◽  
Alpha Synuclein ◽  
Phosphatase 2A ◽  
Alpha Synuclein Aggregation ◽  
The Brain ◽  
Neighboring Neuron

A pathological hallmark of Parkinson’s disease (PD) is formation of Lewy bodies in neurons of the brain. This has been attributed to the spread of α-synuclein (α-syn) aggregates, which involves release of α-syn from a neuron and its reuptake by a neighboring neuron. We found that treatment with plasma from PD patients induced more α-syn phosphorylation and oligomerization than plasma from normal subjects (NS). Compared with NS plasma, PD plasma added to primary neuron cultures caused more cell death in the presence of extracellular α-syn. This was supported by the observations that phosphorylated α-syn oligomers entered neurons, rapidly increased accumulated thioflavin S-positive inclusions, and induced a series of metabolic changes that included activation of polo-like kinase 2, inhibition of glucocerebrosidase and protein phosphatase 2A, and reduction of ceramide levels, all of which have been shown to promote α-syn phosphorylation and aggregation. We also analyzed neurotoxicity of α-syn oligomers relative to plasma from different patients. Neurotoxicity was not related to age or gender of the patients. However, neurotoxicity was positively correlated with H&Y staging score. The modification in the plasma may promote spreading of α-syn aggregates via an alternative pathway and accelerate progression of PD.

scholarly journals IPSC-derived midbrain astrocytes from Parkinson’s disease patients carrying pathogenic SNCA mutations exhibit alpha-synuclein aggregation, mitochondrial fragmentation and excess calcium release

2020 ◽  
Author(s):  
Peter A. Barbuti ◽  
Paul Antony ◽  
Gabriella Novak ◽  
Simone B. Larsen ◽  
Clara Berenguer-Escuder ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Calcium Release ◽  
Cytosolic Calcium ◽  
Alpha Synuclein ◽  
List Type ◽  
Cellular Model ◽  
Functional Impairments ◽  
Mitochondrial Fragmentation ◽  
Serum Free

AbstractParkinson’s disease (PD) is characterized by the loss of A9 midbrain dopaminergic neurons and the accumulation of alpha-synuclein aggregates in remaining neurons. Many studies of the molecular and cellular basis of neurodegeneration in PD have made use of iPSC-derived neurons from patients with familial PD mutations. However, approximately half of the cells in the brain are glia, and their role facilitating neurodegeneration is unclear. We developed a novel serum-free protocol to generate midbrain astrocytes from patient-derived iPSCs harbouring the pathogenic p.A30P, p.A53T mutations in SNCA, as well as duplication and triplication of the SNCA locus. In our cellular model, aggregates of alpha-synuclein occurred only within the GFAP+ astrocytes carrying the pathogenic SNCA mutations. Assessment of spontaneous cytosolic calcium (Ca2+) release using Fluo4 revealed that SNCA mutant astrocytes released excess Ca2+ compared to controls. Unbiased evaluation of 3D mitochondrial morphometric parameters showed that these SNCA mutant astrocytes had increased mitochondrial fragmentation and decreased mitochondrial connectivity compared to controls, and reduced mitochondrial bioenergetic function. This comprehensive assessment of different pathogenic SNCA mutations derived from PD patients using the same cellular model enabled assessment of the mutation effect, showing that p.A53T and triplication astrocytes were the most severely affected. Together, our results indicate that astrocytes harbouring the familial PD mutations in SNCA are dysfunctional, suggesting a contributory role for dysfunctional astrocytes in the disease mechanism and pathogenesis of PD.Table of Contents ImageMain PointsWe used a novel serum-free protocol to generate midbrain-specific functional astrocytes from Parkinson’s disease patients carrying pathological mutations in SNCAPatient-derived astrocytes show morphological and functional impairments

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