scholarly journals Small Molecules Attenuate the Interplay between Conformational Fluctuations, Early Oligomerization and Amyloidosis of Alpha Synuclein

2017 ◽  
Author(s):  
Amrita Kundu ◽  
Sumanta Ghosh ◽  
Krishnananda Chattopadhyay
Keyword(s):  
Single Molecule ◽  
Early Stage ◽  
Neuroblastoma Cells ◽  
Alpha Synuclein ◽  
Inhibitor Molecule ◽  
Transient Nature ◽  
Fluorescence Measurements ◽  
Late Event ◽  
Alpha Synuclein Aggregation

AbstractAggregation of alpha synuclein has strong implications in Parkinson’s disease. The heterogeneity of folding/aggregation landscape and transient nature of the early intermediates result in difficulty in developing a successful therapeutic intervention. Here we used fluorescence measurements at ensemble and single molecule resolution to study how the late and early events of alpha synuclein aggregation modulate each other. The in-vitro aggregation data was complemented using measurements inside live neuroblastoma cells by employing a small molecule labeling technique. An inhibitor molecule (arginine), which delayed the late event of amyloidosis, was found to bind to the protein, shifting the early conformational fluctuations towards a compact state. In contrast, a facilitator of late aggregation (glutamate), was found to be excluded from the protein surface. The presence of glutamate was found to speed up the oligomer formation at the early stage. We found that the effects of the inhibitor and facilitator were additive and as a result they maintained a ratio at which they cancelled each other’s influence on different stages of alpha synuclein aggregation.

The Compound ATH434 Prevents Alpha-Synuclein Toxicity in a Murine Model of Multiple System Atrophy

2021 ◽  
pp. 1-11
Author(s):  
David I. Finkelstein ◽  
Jay J. Shukla ◽  
Robert A. Cherny ◽  
Jessica L. Billings ◽  
Eiman Saleh ◽  
...  
Keyword(s):  
Multiple System Atrophy ◽  
Pharmacokinetic Profile ◽  
Alpha Synuclein ◽  
Redox Activity ◽  
Substantia Nigra Pars Compacta ◽  
Drug Candidate ◽  
Older Volunteers ◽  
Control Food ◽  
Alpha Synuclein Aggregation

Background: An elevation in iron levels, together with an accumulation of α-synuclein within the oligodendrocytes, are features of the rare atypical parkinsonian disorder, Multiple System Atrophy (MSA). We have previously tested the novel compound ATH434 (formally called PBT434) in preclinical models of Parkinson’s disease and shown that it is brain-penetrant, reduces iron accumulation and iron mediated redox activity, provides neuroprotection, inhibits alpha synuclein aggregation and lowers the tissue levels of alpha synuclein. The compound was also well-tolerated in a first-in-human oral dosing study in healthy and older volunteers with a favorable, dose-dependent pharmacokinetic profile. Objective: To evaluate the efficacy of ATH434 in a mouse MSA model. Methods: The PLP-α-syn transgenic mouse overexpresses α-synuclein, demonstrates oligodendroglial pathology, and manifests motor and non-motor aspects of MSA. Animals were provided ATH434 (3, 10, or 30 mg/kg/day spiked into their food) or control food for 4 months starting at 12 months of age and were culled at 16 months. Western blot was used to assess oligomeric and urea soluble α-synuclein levels in brain homogenates, whilst stereology was used to quantitate the number of nigral neurons and glial cell inclusions (GCIs) present in the substantia nigra pars compacta. Results: ATH434 reduced oligomeric and urea soluble α-synuclein aggregation, reduced the number of GCIs, and preserved SNpc neurons. In vitro experiments suggest that ATH434 prevents the formation of toxic oligomeric species of synuclein. Conclusion: ATH434 is a promising small molecule drug candidate that has potential to move forward to trial for treating MSA.

scholarly journals Direct Correlation Between Ligand-Induced α-Synuclein Oligomers and Amyloid-like Fibril Growth

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Martin Nors Pedersen ◽  
Vito Foderà ◽  
Istvan Horvath ◽  
Andreas van Maarschalkerweerd ◽  
Katrine Nørgaard Toft ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Small Angle ◽  
Alpha Synuclein ◽  
X Ray ◽  
Transient Nature ◽  
X Ray Scattering ◽  
Amyloid Deposits ◽  
Potential Link ◽  
Presence And Absence

Abstract Aggregation of proteins into amyloid deposits is the hallmark of several neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. The suggestion that intermediate oligomeric species may be cytotoxic has led to intensified investigations of pre-fibrillar oligomers, which are complicated by their transient nature and low population. Here we investigate alpha-synuclein oligomers, enriched by a 2-pyridone molecule (FN075) and the conversion of oligomers into fibrils. As probed by leakage assays, the FN075 induced oligomers potently disrupt vesicles in vitro, suggesting a potential link to disease related degenerative activity. Fibrils formed in the presence and absence of FN075 are indistinguishable on microscopic and macroscopic levels. Using small angle X-ray scattering, we reveal that FN075 induced oligomers are similar, but not identical, to oligomers previously observed during alpha-synuclein fibrillation. Since the levels of FN075 induced oligomers correlate with the amounts of fibrils among different FN075:protein ratios, the oligomers appear to be on-pathway and modeling supports an ‘oligomer stacking model’ for alpha-synuclein fibril elongation.

scholarly journals CLR01 protects dopaminergic neurons in vitro and in mouse models of Parkinson’s disease

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nora Bengoa-Vergniory ◽  
Emilie Faggiani ◽  
Paula Ramos-Gonzalez ◽  
Ecem Kirkiz ◽  
Natalie Connor-Robson ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Clinical Investigation ◽  
Induced Pluripotent Stem Cell ◽  
Alpha Synuclein ◽  
Dopamine Neurons ◽  
Molecular Tweezers ◽  
Alpha Synuclein Aggregation

Abstract Parkinson’s disease (PD) affects millions of patients worldwide and is characterized by alpha-synuclein aggregation in dopamine neurons. Molecular tweezers have shown high potential as anti-aggregation agents targeting positively charged residues of proteins undergoing amyloidogenic processes. Here we report that the molecular tweezer CLR01 decreased aggregation and toxicity in induced pluripotent stem cell-derived dopaminergic cultures treated with PD brain protein extracts. In microfluidic devices CLR01 reduced alpha-synuclein aggregation in cell somas when axonal terminals were exposed to alpha-synuclein oligomers. We then tested CLR01 in vivo in a humanized alpha-synuclein overexpressing mouse model; mice treated at 12 months of age when motor defects are mild exhibited an improvement in motor defects and a decreased oligomeric alpha-synuclein burden. Finally, CLR01 reduced alpha-synuclein-associated pathology in mice injected with alpha-synuclein aggregates into the striatum or substantia nigra. Taken together, these results highlight CLR01 as a disease-modifying therapy for PD and support further clinical investigation.

scholarly journals Queuine, a bacterial derived hypermodified nucleobase, shows protection in in vitro models of neurodegeneration

2021 ◽  
Author(s):  
Patricia Richard ◽  
Xavier Manière ◽  
Lucie Kozlowski ◽  
Hélène Guillorit ◽  
Patrice Garnier ◽  
...  
Keyword(s):  
Neurodegenerative Disorders ◽  
Therapeutic Potential ◽  
Mrna Translation ◽  
Alpha Synuclein ◽  
In Vitro Models ◽  
Wobble Position ◽  
Mitochondrial Defects ◽  
Alpha Synuclein Aggregation ◽  
The Brain

AbstractGrowing evidence suggests that human gut bacteria, comprising the microbiome that communicates with the brain through the so-called ‘gut-brain-axis’, are linked to neurodegenerative disorders. Imbalances in the microbiome of Parkinson’s disease (PD) and Alzheimer’s disease (AD) patients have been detected in several studies. Queuine is a hypermodified nucleobase enriched in the brain and exclusively produced by bacteria and salvaged by humans through their gut epithelium. Queuine replaces guanine at the wobble position of tRNAs with GUN anticodons and promotes efficient cytoplasmic and mitochondrial mRNA translation.To elucidate whether queuine could facilitate protein folding and prevent aggregation and mitochondrial defects, hallmarks of neurodegenerative disorders, we tested the effect of chemically synthesized queuine, STL-101, in several in vitro models of neurodegeneration. Treatment with STL-101 led to increased neuronal survival as well as a significant decrease in hyper-phosphorylated alpha-synuclein, a marker of alpha-synuclein aggregation in a PD model and a decrease in tau hyperphosphorylation in an AD model. Our work has identified a new role for queuine in neuroprotection uncovering a therapeutic potential for STL-101 in neurological disorders.

scholarly journals Potent inhibitors of toxic alpha-synuclein identified via cellular time-resolved FRET biosensors

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Anthony R. Braun ◽  
Elly E. Liao ◽  
Mian Horvath ◽  
Prakriti Kalra ◽  
Karen Acosta ◽  
...  
Keyword(s):  
Drug Discovery ◽  
Single Molecule ◽  
Conformational Changes ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Alpha Synuclein ◽  
Time Resolved ◽  
Primary Mouse ◽  
Fret Biosensors

AbstractWe have developed a high-throughput drug discovery platform, measuring fluorescence resonance energy transfer (FRET) with fluorescent alpha-synuclein (αSN) biosensors, to detect spontaneous pre-fibrillar oligomers in living cells. Our two αSN FRET biosensors provide complementary insight into αSN oligomerization and conformation in order to improve the success of drug discovery campaigns for the treatment of Parkinson’s disease. We measure FRET by fluorescence lifetime, rather than traditional fluorescence intensity, providing a structural readout with greater resolution and precision. This facilitates identification of compounds that cause subtle but significant conformational changes in the ensemble of oligomeric states that are easily missed using intensity-based FRET. We screened a 1280-compound small-molecule library and identified 21 compounds that changed the lifetime by >5 SD. Two of these compounds have nanomolar potency in protecting SH-SY5Y cells from αSN-induced death, providing a nearly tenfold improvement over known inhibitors. We tested the efficacy of several compounds in a primary mouse neuron assay of αSN pathology (phosphorylation of mouse αSN pre-formed fibrils) and show rescue of pathology for two of them. These hits were further characterized with biophysical and biochemical assays to explore potential mechanisms of action. In vitro αSN oligomerization, single-molecule FRET, and protein-observed fluorine NMR experiments demonstrate that these compounds modulate αSN oligomers but not monomers. Subsequent aggregation assays further show that these compounds also deter or block αSN fibril assembly.

scholarly journals Quantitative comparison between sub-millisecond time resolution single-molecule FRET measurements and 10-second molecular simulations of a biosensor protein

2020 ◽  
Vol 16 (11) ◽  
pp. e1008293
Author(s):  
Dylan Girodat ◽  
Avik K. Pati ◽  
Daniel S. Terry ◽  
Scott C. Blanchard ◽  
Karissa Y. Sanbonmatsu
Keyword(s):  
Time Scales ◽  
Single Molecule ◽  
Conformational Changes ◽  
Time Resolution ◽  
Large Scale ◽  
Md Simulations ◽  
Orientation Factor ◽  
Ribonucleoprotein Complexes ◽  
Fluorescence Measurements

Molecular Dynamics (MD) simulations seek to provide atomic-level insights into conformationally dynamic biological systems at experimentally relevant time resolutions, such as those afforded by single-molecule fluorescence measurements. However, limitations in the time scales of MD simulations and the time resolution of single-molecule measurements have challenged efforts to obtain overlapping temporal regimes required for close quantitative comparisons. Achieving such overlap has the potential to provide novel theories, hypotheses, and interpretations that can inform idealized experimental designs that maximize the detection of the desired reaction coordinate. Here, we report MD simulations at time scales overlapping with in vitro single-molecule Förster (fluorescence) resonance energy transfer (smFRET) measurements of the amino acid binding protein LIV-BPSS at sub-millisecond resolution. Computationally efficient all-atom structure-based simulations, calibrated against explicit solvent simulations, were employed for sampling multiple cycles of LIV-BPSS clamshell-like conformational changes on the time scale of seconds, examining the relationship between these events and those observed by smFRET. The MD simulations agree with the smFRET measurements and provide valuable information on local dynamics of fluorophores at their sites of attachment on LIV-BPSS and the correlations between fluorophore motions and large-scale conformational changes between LIV-BPSS domains. We further utilize the MD simulations to inform the interpretation of smFRET data, including Förster radius (R0) and fluorophore orientation factor (κ2) determinations. The approach we describe can be readily extended to distinct biochemical systems, allowing for the interpretation of any FRET system conjugated to protein or ribonucleoprotein complexes, including those with more conformational processes, as well as those implementing multi-color smFRET.

In Vitro Characterization of Urea Derivatives to Inhibit Alpha-Synuclein Early-stage Aggregation

2021 ◽  
pp. 131569
Author(s):  
Soham Maity ◽  
Kazuma Shimanaka ◽  
Laken N. Rivet ◽  
Malikah O'Dell ◽  
Anisa M. Rashid ◽  
...  
Keyword(s):  
Early Stage ◽  
Alpha Synuclein ◽  
Urea Derivatives ◽  
In Vitro Characterization
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