scholarly journals The Hsc70 Disaggregation Machinery Removes Monomer Units Directly from α-Synuclein Fibril Ends

2020 ◽  
Author(s):  
Matthias M. Schneider ◽  
Saurabh Gautam ◽  
Therese W. Herling ◽  
Ewa Andrzejewska ◽  
Georg Krainer ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Neurodegenerative Diseases ◽  
De Novo ◽  
Dissociation Constants ◽  
Cellular Protein ◽  
Alpha Synuclein ◽  
Amyloid Formation ◽  
Nucleotide Exchange ◽  
Wide Range

AbstractMolecular chaperones contribute to the maintenance of cellular protein homeostasis through a wide range of mechanisms, including the assistance of de novo protein folding, the rescue of misfolded proteins, and the prevention of amyloid formation. Chaperones of the Hsp70 family have a striking capability of disaggregating otherwise irreversible aggregate structures such as amyloid fibrils that accumulate during the development of neurodegenerative diseases. However, the mechanisms of this key emerging functionality remain largely unknown. Here, we bring together microfluidic measurements with kinetic analysis and show that that the Hsp70 protein heat chock complement Hsc70 together with its two co-chaperones DnaJB1 and the nucleotide exchange factor Apg2 is able to completely reverse the aggregation process of alpha-synuclein, associated with Parkinson’s disease, back to its soluble monomeric state. Moreover, we show that this reaction proceeds with first order kinetics in a process where monomer units are taken off directly from the fibril ends. Our results demonstrate that all components of the chaperone triad are essential for fibril disaggregation. Lastly, we quantify the interactions between the three chaperones as well as between the chaperones and the fibrils in solution, yielding both binding stoichiometries and dissociation constants. Crucially, we find that the stoichiometry of Hsc70 binding to fibrils suggests Hsc70 clustering at the fibril ends. Taken together, our results show that the mechanism of action of the Hsc70–DnaJB1–Apg2 chaperone system in disaggregating α-synuclein fibrils involves the removal of monomer units without any intermediate fragmentation steps. These findings are fundamental to our understanding of the suppression of amyloid proliferation early in life and the natural clearance mechanisms of fibrillar deposits in Parkinson’s disease, and inform on the possibilities and limitations of this strategy in the development of therapeutics against synucleinopathies and related neurodegenerative diseases.

scholarly journals The Prion-Like Spreading of Alpha-Synuclein in Parkinson’s Disease: Update on Models and Hypotheses

2021 ◽  
Vol 22 (15) ◽  
pp. 8338
Author(s):  
Asad Jan ◽  
Nádia Pereira Gonçalves ◽  
Christian Bjerggaard Vaegter ◽  
Poul Henning Jensen ◽  
Nelson Ferreira
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Molecular Mechanisms ◽  
De Novo ◽  
Alpha Synuclein ◽  
Experimental Models ◽  
Cellular Factors ◽  
Recent Developments ◽  
Novel Targets ◽  
Presynaptic Protein

The pathological aggregation of the presynaptic protein α-synuclein (α-syn) and propagation through synaptically coupled neuroanatomical tracts is increasingly thought to underlie the pathophysiological progression of Parkinson’s disease (PD) and related synucleinopathies. Although the precise molecular mechanisms responsible for the spreading of pathological α-syn accumulation in the CNS are not fully understood, growing evidence suggests that de novo α-syn misfolding and/or neuronal internalization of aggregated α-syn facilitates conformational templating of endogenous α-syn monomers in a mechanism reminiscent of prions. A refined understanding of the biochemical and cellular factors mediating the pathological neuron-to-neuron propagation of misfolded α-syn will potentially elucidate the etiology of PD and unravel novel targets for therapeutic intervention. Here, we discuss recent developments on the hypothesis regarding trans-synaptic propagation of α-syn pathology in the context of neuronal vulnerability and highlight the potential utility of novel experimental models of synucleinopathies.

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 Alpha-Synuclein in the Gastrointestinal Tract as a Potential Biomarker for Early Detection of Parkinson’s Disease

2020 ◽  
Vol 21 (22) ◽  
pp. 8666
Author(s):  
Dominika Fricova ◽  
Jana Harsanyiova ◽  
Alzbeta Kralova Trancikova
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Neurodegenerative Diseases ◽  
Clinical Symptoms ◽  
Neuronal Degeneration ◽  
Alpha Synuclein ◽  
Diagnostic Methods ◽  
Alternative Methods ◽  
Peripheral Tissues ◽  
Potential Biomarker

The primary pathogenesis associated with Parkinson’s disease (PD) occurs in peripheral tissues several years before the onset of typical motor symptoms. Early and reliable diagnosis of PD could provide new treatment options for PD patients and improve their quality of life. At present, however, diagnosis relies mainly on clinical symptoms, and definitive diagnosis is still based on postmortem pathological confirmation of dopaminergic neuronal degeneration. In addition, the similarity of the clinical, cognitive, and neuropathological features of PD with other neurodegenerative diseases calls for new biomarkers, suitable for differential diagnosis. Alpha-synuclein (α-Syn) is a potential PD biomarker, due to its close connection with the pathogenesis of the disease. Here we summarize the currently available information on the possible use of α-Syn as a biomarker of early stages of PD in gastrointestinal (GI) tissues, highlight its potential to distinguish PD and other neurodegenerative diseases, and suggest alternative methods (primarily developed for other tissue analysis) that could improve α-Syn detection procedures or diagnostic methods in general.

scholarly journals High diagnostic performance of independent alpha-synuclein seed amplification assays for detection of early Parkinson’s disease

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Marco J. Russo ◽  
Christina D. Orru ◽  
Luis Concha-Marambio ◽  
Simone Giaisi ◽  
Bradley R. Groveman ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Clinical Diagnosis ◽  
Diagnostic Performance ◽  
De Novo ◽  
Alpha Synuclein ◽  
Diagnostic Tools ◽  
Dat Spect ◽  
Progression Markers ◽  
Early Parkinson’S Disease

AbstractAlpha-synuclein seed amplification assays (αSyn-SAAs) are promising diagnostic tools for Parkinson’s disease (PD) and related synucleinopathies. They enable detection of seeding-competent alpha-synuclein aggregates in living patients and have shown high diagnostic accuracy in several PD and other synucleinopathy patient cohorts. However, there has been confusion about αSyn-SAAs for their methodology, nomenclature, and relative accuracies when performed by various laboratories. We compared αSyn-SAA results obtained from three independent laboratories to evaluate reproducibility across methodological variations. We utilized the Parkinson’s Progression Markers Initiative (PPMI) cohort, with DATSCAN data available for comparison, since clinical diagnosis of early de novo PD is critical for neuroprotective trials, which often use dopamine transporter imaging to enrich their cohorts. Blinded cerebrospinal fluid (CSF) samples for a randomly selected subset of PPMI subjects (30 PD, 30 HC, and 20 SWEDD), from both baseline and year 3 collections for the PD and HC groups (140 total CSF samples) were analyzed in parallel by each lab according to their own established and optimized αSyn-SAA protocols. The αSyn-SAA results were remarkably similar across laboratories, displaying high diagnostic performance (sensitivity ranging from 86 to 96% and specificity from 93 to 100%). The assays were also concordant for samples with results that differed from clinical diagnosis, including 2 PD patients determined to be clinically inconsistent with PD at later time points. All three assays also detected 2 SWEDD subjects as αSyn-SAA positive who later developed PD with abnormal DAT-SPECT. These multi-laboratory results confirm the reproducibility and value of αSyn-SAA as diagnostic tools, illustrate reproducibility of the assay in expert hands, and suggest that αSyn-SAA has potential to provide earlier diagnosis with comparable or superior accuracy to existing methods.

scholarly journals Abnormal Vision-Based Displacement Perception in Parkinson’s Disease

2021 ◽  
Vol 15 ◽  
Author(s):  
Matthew Bernardinis ◽  
S. Farokh Atashzar ◽  
Rajni V. Patel ◽  
Mandar S. Jog
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Visual Processing ◽  
De Novo ◽  
Early Stage ◽  
Absolute Measurement ◽  
Motor Disorder ◽  
Independent Manner ◽  
Graphical Tool ◽  
Wide Range

In this work, we investigate the effect of Parkinson’s disease (PD), and common corresponding therapies on vision-based perception of motion, a critical perceptual ability required for performing a wide range of activities of daily livings. While PD has been recognized as mainly a motor disorder, sensory manifestation of PD can also play a major role in the resulting disability. In this paper, for the first time, the effect of disease duration and common therapies on vision-based perception of displacement were investigated. The study is conducted in a movement-independent manner, to reject the shadowing effects and isolate the targeted perceptual disorder to the maximum possible extent. Data was collected using a computerized graphical tool on 37 PD patients [6 early-stage de novo, 25 mid-stage using levodopa therapy, six later-stage using deep brain stimulation (DBS)] and 15 control participants. Besides the absolute measurement of perception through a psychometric analysis on two tested position reference magnitudes, we also investigated the linearity in perception using Weber’s fraction. The results showed that individuals with PD displayed significant perceptual impairments compared to controls, though early-stage patients were not impaired. Mid-stage patients displayed impairments at the greater of the two tested reference magnitudes, while late-stage patients were impaired at both reference magnitudes. Levodopa and DBS use did not cause statistically significant differences in absolute displacement perception. The findings suggest abnormal visual processing in PD increasing with disease development, perhaps contributing to sensory-based impairments of PD such as bradykinesia, visuospatial deficits, and abnormal object recognition.

scholarly journals Rab2 is a potent new target for enhancing autophagy in the treatment of Parkinson’s disease

2020 ◽  
Author(s):  
Janka Szinyákovics ◽  
Eszter Kiss ◽  
Fanni Keresztes ◽  
Tibor Vellai ◽  
Tibor Kovács
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Neurodegenerative Diseases ◽  
Drug Targets ◽  
Disease Model ◽  
Alpha Synuclein ◽  
Small Gtpase ◽  
Rab Proteins ◽  
Receptor Complexes ◽  
Complex Forms

AbstractMacroautophagy is a lysosomal-dependent degradational pathway of eukaryotic cells, during which toxic, unnecessary, and damaged intracellular components are broken down. Autophagic activity declines with age, and this change could contribute to the accumulation of intracellular damage at advanced ages, causing cells to lose their functionality and vitality. This could be particularly problematic in post-mitotic cells include neurons, the mass destruction of which leads to different neurodegenerative diseases.We aim to discover new regulation points where autophagy could be specifically activated, and test these potential drug targets in Drosophila neurodegenerative disease models. One possible way to activate autophagy is through the enhancement of autophagosome-lysosome fusion to become autolysosome. This fusion is regulated by HOPS (homotypic fusion and protein sorting) and SNARE (Snap receptor) complexes. The HOPS complex forms a bridge between lysosome and autophagosome with the assistance of small GTPase Rab (Ras-associated binding) proteins. Thus, Rab proteins are essential for autolysosome maturation, and among Rab proteins, Rab2 is required for the degradation of autophagic cargo.Our results revealed that GTP-locked (constitutively active) Rab2 (Rab2 CA) expression reduces the levels of the autophagic substrate p62/Ref2P in dopaminergic neurons, and improved the climbing ability of animals during aging. The expression of Rab2 CA also increased lifespan in a Parkinson’s disease model (human mutant alpha-synuclein [A53T] overexpressed animals). In these animals, Rab2 CA expression significantly increased autophagic degradation as compared to control. These results may reveal a new, more specific drug target for autophagic activation treating today’s incurable neurodegenerative diseases.

Bioinorganic Chemistry of Parkinson’s Disease: Structural Determinants for the Copper-Mediated Amyloid Formation of Alpha-Synuclein

2010 ◽  
Vol 49 (22) ◽  
pp. 10668-10679 ◽  
Author(s):  
Andrés Binolfi ◽  
Esaú E. Rodriguez ◽  
Daniela Valensin ◽  
Nicola D’Amelio ◽  
Emiliano Ippoliti ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Bioinorganic Chemistry ◽  
Alpha Synuclein ◽  
Amyloid Formation ◽  
Structural Determinants

scholarly journals Streamlined alpha-synuclein RT-QuIC assay for various biospecimens in Parkinson’s disease and dementia with Lewy bodies

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Connor Bargar ◽  
Wen Wang ◽  
Steven A. Gunzler ◽  
Alexandra LeFevre ◽  
Zerui Wang ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Dementia With Lewy Bodies ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Peripheral Tissues ◽  
Potential Biomarker ◽  
Wide Range ◽  
Different Types ◽  
Diagnostic Values

AbstractDefinitive diagnosis of Parkinson’s disease (PD) and dementia with Lewy bodies (DLB) relies on postmortem finding of disease-associated alpha-synuclein (αSynD) as misfolded protein aggregates in the central nervous system (CNS). The recent development of the real-time quaking induced conversion (RT-QuIC) assay for ultrasensitive detection of αSynD aggregates has revitalized the diagnostic values of clinically accessible biospecimens, including cerebrospinal fluid (CSF) and peripheral tissues. However, the current αSyn RT-QuIC assay platforms vary widely and are thus challenging to implement and standardize the measurements of αSynD across a wide range of biospecimens and in different laboratories. We have streamlined αSyn RT-QuIC assay based on a second generation assay platform that was assembled entirely with commercial reagents. The streamlined RT-QuIC method consisted of a simplified protocol requiring minimal hands-on time, and allowing for a uniform analysis of αSynD in different types of biospecimens from PD and DLB. Ultrasensitive and specific RT-QuIC detection of αSynD aggregates was achieved in million-fold diluted brain homogenates and in nanoliters of CSF from PD and DLB cases but not from controls. Comparative analysis revealed higher seeding activity of αSynD in DLB than PD in both brain homogenates and CSF. Our assay was further validated with CSF samples of 214 neuropathologically confirmed cases from tissue repositories (88 PD, 58 DLB, and 68 controls), yielding a sensitivity of 98% and a specificity of 100%. Finally, a single RT-QuIC assay protocol was employed uniformly to detect seeding activity of αSynD in PD samples across different types of tissues including the brain, skin, salivary gland, and colon. We anticipate that our streamlined protocol will enable interested laboratories to easily and rapidly implement the αSyn RT-QuIC assay for various clinical specimens from PD and DLB. The utilization of commercial products for all assay components will improve the robustness and standardization of the RT-QuIC assay for diagnostic applications across different sites. Due to ultralow sample consumption, the ultrasensitive RT-QuIC assay will facilitate efficient use and sharing of scarce resources of biospecimens. Our streamlined RT-QuIC assay is suitable to track the distribution of αSynD in CNS and peripheral tissues of affected patients. The ongoing evaluation of RT-QuIC assay of αSynD as a potential biomarker for PD and DLB in clinically accessible biospecimens has broad implications for understanding disease pathogenesis, improving early and differential diagnosis, and monitoring therapeutic efficacies in clinical trials.

scholarly journals Animal models of Parkinson's disease: a guide to selecting the optimal model for your research

2021 ◽  
Author(s):  
Joana Lama ◽  
Yazead Buhidma ◽  
Edward JR Fletcher ◽  
Susan Duty
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Animal Models ◽  
Dopaminergic Neurons ◽  
Alpha Synuclein ◽  
Motor Symptoms ◽  
Multisystem Disorder ◽  
Wide Range ◽  
Non Motor Symptoms ◽  
Selection Of

Parkinson’s disease (PD) is a complex, multisystem disorder characterised by alpha synuclein pathology, degeneration of nigrostriatal dopaminergic neurons, multifactorial pathogenetic mechanisms and expression of a plethora of motor and non-motor symptoms. Animal models of PD have already been instructive in helping us unravel some of these aspects. However, much remains to be discovered, requiring continued interrogation by the research community. In contrast to the situation for many neurological disorders, PD benefits from of a wide range of available animal models (pharmacological, toxin, genetic and alpha-synuclein) but this makes selection of the optimal one for a given study difficult. This is especially so when a study demands a model that displays a specific combination of features. While many excellent reviews of animal models already exist, this review takes a different approach with the intention of more readily informing this decision-making process. We have considered each feature of PD in turn - aetiology, pathology, pathogenesis, motor dysfunctions and non-motor symptoms - highlighting those animal models that replicate each. By compiling easily accessible tables and figures, we aim to provide the reader with a simple, go-to resource for selecting the optimal animal model of PD to suit their research needs.

Sign in / Sign up

Export Citation Format

Share Document