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Polymorphism of Alpha-Synuclein Amyloid Fibrils Depends on Ionic Strength and Protein Concentration.International Journal of Molecular... Nov 2021Protein aggregate formation is linked with multiple amyloidoses, including Alzheimer's and Parkinson's diseases. Currently, the understanding of such fibrillar structure...
Protein aggregate formation is linked with multiple amyloidoses, including Alzheimer's and Parkinson's diseases. Currently, the understanding of such fibrillar structure formation and propagation is still not sufficient, the outcome of which is a lack of potent, anti-amyloid drugs. The environmental conditions used during in vitro protein aggregation assays play an important role in determining both the aggregation kinetic parameters, as well as resulting fibril structure. In the case of alpha-synuclein, ionic strength has been shown as a crucial factor in its amyloid aggregation. In this work, we examine a large sample size of alpha-synuclein aggregation reactions under thirty different ionic strength and protein concentration combinations and determine the resulting fibril structural variations using their dye-binding properties, secondary structure and morphology. We show that both ionic strength and protein concentration determine the structural variability of alpha-synuclein amyloid fibrils and that sometimes even identical conditions can result in up to four distinct types of aggregates.
Topics: Amyloid; In Vitro Techniques; Kinetics; Osmolar Concentration; Parkinson Disease; Protein Aggregates; Protein Aggregation, Pathological; Protein Binding; Protein Structure, Secondary; alpha-Synuclein
PubMed: 34830264
DOI: 10.3390/ijms222212382 -
Acta Neuropathologica Mar 2022Synucleinopathies are a group of clinically and neuropathologically distinct protein misfolding diseases caused by unique α-synuclein conformations, or strains. While... (Review)
Review
Synucleinopathies are a group of clinically and neuropathologically distinct protein misfolding diseases caused by unique α-synuclein conformations, or strains. While multiple atomic resolution cryo-electron microscopy structures of α-synuclein fibrils are now deposited in Protein Data Bank, significant gaps in the biological consequences arising from each conformation have yet to be unraveled. Mutations in the α-synuclein gene (SNCA), cofactors, and the solvation environment contribute to the formation and maintenance of each disease-causing strain. This review highlights the impact of each of these factors on α-synuclein misfolding and discusses the implications of the resulting structural variability on therapeutic development.
Topics: Biology; Cryoelectron Microscopy; Humans; Proteostasis Deficiencies; Synucleinopathies; alpha-Synuclein
PubMed: 35122113
DOI: 10.1007/s00401-022-02403-w -
Nature Communications Apr 2021The molecular architecture of α-Synuclein (α-Syn) inclusions, pathognomonic of various neurodegenerative disorders, remains unclear. α-Syn inclusions were long...
The molecular architecture of α-Synuclein (α-Syn) inclusions, pathognomonic of various neurodegenerative disorders, remains unclear. α-Syn inclusions were long thought to consist mainly of α-Syn fibrils, but recent reports pointed to intracellular membranes as the major inclusion component. Here, we use cryo-electron tomography (cryo-ET) to image neuronal α-Syn inclusions in situ at molecular resolution. We show that inclusions seeded by α-Syn aggregates produced recombinantly or purified from patient brain consist of α-Syn fibrils crisscrossing a variety of cellular organelles. Using gold-labeled seeds, we find that aggregate seeding is predominantly mediated by small α-Syn fibrils, from which cytoplasmic fibrils grow unidirectionally. Detailed analysis of membrane interactions revealed that α-Syn fibrils do not contact membranes directly, and that α-Syn does not drive membrane clustering. Altogether, we conclusively demonstrate that neuronal α-Syn inclusions consist of α-Syn fibrils intermixed with membranous organelles, and illuminate the mechanism of aggregate seeding and cellular interaction.
Topics: Brain; Cryoelectron Microscopy; Humans; Inclusion Bodies; Multiple System Atrophy; Neurons; alpha-Synuclein
PubMed: 33854052
DOI: 10.1038/s41467-021-22108-0 -
Translational Neurodegeneration 2020α-Synuclein is a small soluble protein, whose physiological function in the healthy brain is poorly understood. Intracellular inclusions of α-synuclein, referred to as... (Review)
Review
BACKGROUND
α-Synuclein is a small soluble protein, whose physiological function in the healthy brain is poorly understood. Intracellular inclusions of α-synuclein, referred to as Lewy bodies (LBs), are pathological hallmarks of α-synucleinopathies, such as Parkinson's disease (PD) or dementia with Lewy bodies (DLB).
MAIN BODY
Understanding of the molecular basis as well as the factors or conditions promoting α-synuclein misfolding and aggregation is an important step towards the comprehension of pathological mechanism of α-synucleinopathies and for the development of efficient therapeutic strategies. Based on the conversion and aggregation mechanism of α-synuclein, novel diagnostic tests, such as protein misfolding seeded conversion assays, e.g. the real-time quaking-induced conversion (RT-QuIC), had been developed. In diagnostics, α-synuclein RT-QuIC exhibits a specificity between 82 and 100% while the sensitivity varies between 70 and 100% among different laboratories. In addition, the α-synuclein RT-QuIC can be used to study the α-synuclein-seeding-characteristics of different α-synucleinopathies and to differentiate between DLB and PD.
CONCLUSION
The variable diagnostic accuracy of current α-synuclein RT-QuIC occurs due to different protocols, cohorts and material etc.. An impact of micro-environmental factors on the α-synuclein aggregation and conversion process and the occurrence and detection of differential misfolded α-synuclein types or strains might underpin the clinical heterogeneity of α-synucleinopathies
Topics: Animals; Cellular Microenvironment; Humans; Proteostasis Deficiencies; Synucleinopathies; alpha-Synuclein
PubMed: 31988747
DOI: 10.1186/s40035-019-0181-9 -
Movement Disorders : Official Journal... Mar 2021Parkinson's disease psychosis is a prevalent yet underreported and understudied nonmotor manifestation of Parkinson's disease and, arguably, the most debilitating. It is...
BACKGROUND
Parkinson's disease psychosis is a prevalent yet underreported and understudied nonmotor manifestation of Parkinson's disease and, arguably, the most debilitating. It is unknown if α-synuclein plays a role in psychosis, and if so, this endophenotype may be crucial for elucidating the neurodegenerative process.
OBJECTIVES
We sought to dissect the underlying neurobiology of novelty-induced hyperactivity, reminiscent of psychosis-like behavior, in human α-synuclein BAC rats.
RESULTS
Herein, we demonstrate a prodromal psychosis-like phenotype, including late-onset sensorimotor gating disruption, striatal hyperdopaminergic signaling, and persistent novelty-induced hyperactivity (up to 18 months), albeit reduced baseline locomotor activity, that is augmented by d-amphetamine and reversed by classical and atypical antipsychotics. MicroRNA-mediated α-synuclein downregulation in the ventral midbrain rescues the hyperactive phenotype and restores striatal dopamine levels. This phenotype is accompanied by an abundance of age-, brain region- and gene dose-dependent aberrant α-synuclein, including hyperphosphorylation, C-terminal truncation, aggregation pathology, and mild nigral neurodegeneration (27%).
CONCLUSIONS
Our findings demonstrate a potential role of α-synuclein in Parkinson's disease psychosis and provide evidence of region-specific perturbations prior to neurodegeneration phenoconversion. The reported phenotype coincides with the latest clinical findings that suggest a premotor hyperdopaminergic state may occur, while at the same time, premotor psychotic symptoms are increasingly being recognized. © 2020 International Parkinson and Movement Disorder Society.
Topics: Animals; Disease Models, Animal; Humans; Mice; Mice, Transgenic; Parkinson Disease; Psychotic Disorders; Rats; Rats, Transgenic; Substantia Nigra; alpha-Synuclein
PubMed: 33200461
DOI: 10.1002/mds.28383 -
The Journal of Neuroscience : the... Sep 2022Alpha-synuclein (αSyn) and tau are abundant multifunctional neuronal proteins, and their intracellular deposits have been linked to many neurodegenerative diseases,...
Alpha-synuclein (αSyn) and tau are abundant multifunctional neuronal proteins, and their intracellular deposits have been linked to many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Despite the disease relevance, their physiological roles remain elusive, as mice with knock-out of either of these genes do not exhibit overt phenotypes. To reveal functional cooperation, we generated αSyntau double-knock-out mice and characterized the functional cross talk between these proteins during brain development. Intriguingly, deletion of αSyn and tau reduced Notch signaling and accelerated interkinetic nuclear migration of G2 phase at early embryonic stage. This significantly altered the balance between the proliferative and neurogenic divisions of progenitor cells, resulting in an overproduction of early born neurons and enhanced neurogenesis, by which the brain size was enlarged during the embryonic stage in both sexes. On the other hand, a reduction in the number of neural progenitor cells in the middle stage of corticogenesis diminished subsequent gliogenesis in the αSyntau cortex. Additionally, the expansion and maturation of macroglial cells (astrocytes and oligodendrocytes) were suppressed in the αSyntau postnatal brain, which in turn reduced the male αSyntau brain size and cortical thickness to less than the control values. Our study identifies important functional cooperation of αSyn and tau during corticogenesis. Correct understanding of the physiological functions of αSyn and tau in CNS is critical to elucidate pathogenesis involved in the etiology of neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. We show here that αSyn and tau are cooperatively involved in brain development via maintenance of progenitor cells. αSyn and tau double-knock-out mice exhibited an overproduction of early born neurons and accelerated neurogenesis at early corticogenesis. Furthermore, loss of αSyn and tau also perturbed gliogenesis at later embryonic stage, as well as the subsequent glial expansion and maturation at postnatal brain. Our findings provide new mechanistic insights and extend therapeutic opportunities for neurodegenerative diseases caused by aberrant αSyn and tau.
Topics: Alzheimer Disease; Animals; Female; Male; Mice; Mice, Knockout; Neurodegenerative Diseases; Parkinson Disease; alpha-Synuclein
PubMed: 35906071
DOI: 10.1523/JNEUROSCI.0396-22.2022 -
Cerebellum (London, England) Feb 2024
Topics: Humans; Multiple System Atrophy; Brain; alpha-Synuclein
PubMed: 38307991
DOI: 10.1007/s12311-024-01667-0 -
Biological Chemistry Sep 2020α-Synuclein fibrillation is now regarded as a major pathogenic process in Parkinson's disease and its proteinaceous deposits are also detected in other neurological...
α-Synuclein fibrillation is now regarded as a major pathogenic process in Parkinson's disease and its proteinaceous deposits are also detected in other neurological disorders including Alzheimer's disease. Therefore anti-amyloidegenic compounds may delay or prevent the progression of synucleinopathies disease. Molecular chaperones are group of proteins which mediate correct folding of proteins by preventing unsuitable interactions which may lead to aggregation. The objective of this study was to investigate the anti-amyloidogenic effect of molecular chaperone artemin on α-synuclein. As the concentration of artemin was increased up to 4 μg/ml, a decrease in fibril formation of α-synuclein was observed using thioflavin T (ThT) fluorescence and congo red (CR) assay. Transmission electron microscopy (TEM) images also demonstrated a reduction in fibrils in the presence of artemin. The secondary structure of α-synuclein was similar to its native form prior to fibrillation when incubated with artemin. A cell-based assay has shown that artemin inhibits α-synuclein aggregation and reduce cytotoxicity, apoptosis and reactive oxygen species (ROS) production. Our results revealed that artemin has efficient chaperon activity for preventing α-synuclein fibril formation and toxicity.
Topics: Apoptosis; Cell Line, Tumor; Cell Survival; Humans; Molecular Chaperones; Nerve Tissue Proteins; Protein Aggregates; Protein Aggregation, Pathological; Reactive Oxygen Species; alpha-Synuclein
PubMed: 32673279
DOI: 10.1515/hsz-2019-0446 -
Methods in Molecular Biology (Clifton,... 2023Aggregated alpha-synuclein (α-Syn) in neurons is a hallmark of Parkinson's disease (PD) and other synucleinopathies. Recent advances (1) in the production and...
Aggregated alpha-synuclein (α-Syn) in neurons is a hallmark of Parkinson's disease (PD) and other synucleinopathies. Recent advances (1) in the production and purification of synthetic assemblies of α-Syn, (2) in the design and production of microfluidic devices allowing the construction of oriented and compartmentalized neuronal network on a chip, and (3) in the differentiation of human pluripotent stem cells (hPSCs) into specific neuronal subtypes now allow the study of cellular and molecular determinants of the prion-like properties of α-Syn in vitro. Here, we described the methods we used to reconstruct a cortico-cortical human neuronal network in microfluidic devices and how to take advantage of this cellular model to characterize (1) the prion-like properties of different α-Syn strains and (2) the neuronal dysfunctions and the alterations associated with the exposure to α-Syn strains or the nucleation of endogenous α-Syn protein in vitro.
Topics: Humans; alpha-Synuclein; Neurons; Parkinson Disease; Synucleinopathies; Prions
PubMed: 36310215
DOI: 10.1007/978-1-0716-2597-2_24 -
Journal of Neurochemistry Sep 2019Parkinson's disease is the second most common neurodegenerative disorder worldwide. Neurodegeneration in this pathology is characterized by the loss of dopaminergic... (Review)
Review
Parkinson's disease is the second most common neurodegenerative disorder worldwide. Neurodegeneration in this pathology is characterized by the loss of dopaminergic neurons in the substantia nigra, coupled with cytoplasmic inclusions known as Lewy bodies containing α-synuclein. The brain is an organ that concentrates metal ions, and there is emerging evidence that a break-down in metal homeostasis may be a critical factor in a variety of neurodegenerative diseases. α-synuclein has emerged as an important metal-binding protein in the brain, whereas these interactions play an important role in its aggregation and might represent a link between protein aggregation, oxidative damage, and neuronal cell loss. Additionally, α-synuclein undergoes several post-translational modifications that regulate its structure and physiological function, and may be linked to the aggregation and/or oligomer formation. This review is focused on the interaction of this protein with physiologically relevant metal ions, highlighting the cases where metal-AS interactions profile as key modulators for its structural, aggregation, and membrane-binding properties. The impact of α-synuclein phosphorylation and N-terminal acetylation in the metal-binding properties of the protein are also discussed, underscoring a potential interplay between PTMs and metal ion binding in regulating α-synuclein physiological functions and its role in pathology. This article is part of the Special Issue "Synuclein".
Topics: Acetylation; Binding Sites; Brain; Cations, Divalent; Humans; Metals; Oxidative Stress; Oxygen; Parkinson Disease; Phosphorylation; Protein Aggregation, Pathological; Protein Binding; Protein Domains; Protein Processing, Post-Translational; Structure-Activity Relationship; Sumoylation; alpha-Synuclein
PubMed: 31099098
DOI: 10.1111/jnc.14721