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Journal of Neurochemistry Oct 2016Parkinson's disease belongs to a group of currently incurable neurodegenerative disorders characterized by the misfolding and accumulation of alpha-synuclein aggregates... (Review)
Review
Parkinson's disease belongs to a group of currently incurable neurodegenerative disorders characterized by the misfolding and accumulation of alpha-synuclein aggregates that are commonly known as synucleinopathies. Clinically, synucleinopathies are heterogeneous, reflecting the somewhat selective neuronal vulnerability characteristic of each disease. The precise molecular underpinnings of synucleinopathies remain unclear, but the process of aggregation of alpha-synuclein appears as a central event. However, there is still no consensus with respect to the toxic forms of alpha-synuclein, hampering our ability to use the protein as a target for therapeutic intervention. To decipher the molecular bases of synucleinopathies, it is essential to understand the complex triangle formed between the structure, function and toxicity of alpha-synuclein. Recently, important steps have been undertaken to elucidate the role of the protein in both physiological and pathological conditions. Here, we provide an overview of recent findings in the field of alpha-synuclein research, and put forward a new perspective over paradigms that persist in the field. Establishing whether alpha-synuclein has a causative role in all synucleinopathies will enable the identification of targets for the development of novel therapeutic strategies for this devastating group of disorders. Alpha-synuclein is the speculated cornerstone of several neurodegenerative disorders known as Synucleinopathies. Nevertheless, the mechanisms underlying the pathogenic effects of this protein remain unknown. Here, we review the recent findings in the three corners of alpha-synuclein biology - structure, function and toxicity - and discuss the enigmatic roads that have accompanied alpha-synuclein from the beginning. This article is part of a special issue on Parkinson disease.
Topics: Animals; Humans; Mutation; Neurodegenerative Diseases; Protein Aggregates; Protein Folding; alpha-Synuclein
PubMed: 26190401
DOI: 10.1111/jnc.13249 -
Methods in Molecular Biology (Clifton,... 2019α-Synuclein (αS) is an abundant neuronal protein which has been implicated, among others, in the pathogenesis of neurodegenerative diseases like Parkinson's disease...
α-Synuclein (αS) is an abundant neuronal protein which has been implicated, among others, in the pathogenesis of neurodegenerative diseases like Parkinson's disease (PD) and dementia with Lewy bodies (DLB). In fact, αS is the major constituent of Lewy bodies, the primarily proteinaceous inclusions found in the nervous tissue of PD and DLB patients. While its physiological role is unclear, it is believed to be involved in the regulation of synaptic vesicle exocytosis. However, in a disease state, αS will "misfold" and aggregate, leading to neuronal dysfunction and death. The study of the molecular events underlying pathogenesis, especially with biophysical and biochemical approaches, requires highly pure untagged αS. In this protocol we describe a method to purify untagged recombinant αS, which can be used for binding, folding, and aggregation studies. The purification method includes a cell lysis step, followed by two chromatography steps: ion-exchange chromatography first, and size-exclusion chromatography for polishing.
Topics: Chromatography, Liquid; Gene Expression; Genetic Vectors; Humans; Parkinson Disease; alpha-Synuclein
PubMed: 30771184
DOI: 10.1007/978-1-4939-9124-2_20 -
Experimental Neurology Dec 2017Starting two decades ago with the discoveries of genetic links between alpha-synuclein and Parkinson's disease risk and the identification of aggregated alpha-synuclein... (Review)
Review
Starting two decades ago with the discoveries of genetic links between alpha-synuclein and Parkinson's disease risk and the identification of aggregated alpha-synuclein as the main protein constituent of Lewy pathology, alpha-synuclein has emerged as the major therapeutic target in Parkinson's disease and related synucleinopathies. Following the suggestion that alpha-synuclein pathology gradually spreads through the nervous system following a stereotypic pattern and the discovery that aggregated forms of alpha-synuclein can propagate pathology from one cell to another, and thereby probably aggravate existing deficits as well as generate additional symptoms, the idea that alpha-synuclein is a viable therapeutic target gained further support. In this review we describe current challenges and possibilities with alpha-synuclein as a therapeutic target. We briefly highlight gaps in the knowledge of the role of alpha-synuclein in disease, and propose that a deeper understanding of the pathobiology of alpha-synuclein can lead to improved therapeutic strategies. We describe several treatment approaches that are currently being tested in advanced animal experiments or already are in clinical trials. We have divided them into approaches that reduce alpha-synuclein production; inhibit alpha-synuclein aggregation inside cells; promote its degradation either inside or outside cells; and reduce its uptake by neighbouring cells following release from already affected neurons. Finally, we briefly discuss challenges related to the clinical testing of alpha-synuclein therapies, for example difficulties in monitoring target engagement and the need for relatively large trials of long duration. We conclude that alpha-synuclein remains one of the most compelling therapeutic targets for Parkinson's disease, and related synucleinopathies, and that the multitude of approaches being tested provides hope for the future.
Topics: Animals; Disease Models, Animal; Genetic Therapy; Humans; Multiple System Atrophy; Neurons; Parkinson Disease; alpha-Synuclein
PubMed: 28987463
DOI: 10.1016/j.expneurol.2017.10.003 -
Acta Neuropathologica Nov 2022The predominantly pre-synaptic intrinsically disordered protein α-synuclein is prone to misfolding and aggregation in synucleinopathies, such as Parkinson's disease...
The predominantly pre-synaptic intrinsically disordered protein α-synuclein is prone to misfolding and aggregation in synucleinopathies, such as Parkinson's disease (PD) and Dementia with Lewy bodies (DLB). Molecular chaperones play important roles in protein misfolding diseases and members of the chaperone machinery are often deposited in Lewy bodies. Here, we show that the Hsp90 co-chaperone STI1 co-immunoprecipitated α-synuclein, and co-deposited with Hsp90 and Hsp70 in insoluble protein fractions in two mouse models of α-synuclein misfolding. STI1 and Hsp90 also co-localized extensively with filamentous S129 phosphorylated α-synuclein in ubiquitin-positive inclusions. In PD human brains, STI1 transcripts were increased, and in neurologically healthy brains, STI1 and α-synuclein transcripts correlated. Nuclear Magnetic Resonance (NMR) analyses revealed direct interaction of α-synuclein with STI1 and indicated that the STI1 TPR2A, but not TPR1 or TPR2B domains, interacted with the C-terminal domain of α-synuclein. In vitro, the STI1 TPR2A domain facilitated S129 phosphorylation by Polo-like kinase 3. Moreover, mice over-expressing STI1 and Hsp90ß presented elevated α-synuclein S129 phosphorylation accompanied by inclusions when injected with α-synuclein pre-formed fibrils. In contrast, reduced STI1 function decreased protein inclusion formation, S129 α-synuclein phosphorylation, while mitigating motor and cognitive deficits as well as mesoscopic brain atrophy in α-synuclein-over-expressing mice. Our findings reveal a vicious cycle in which STI1 facilitates the generation and accumulation of toxic α-synuclein conformers, while α-synuclein-induced proteostatic stress increased insoluble STI1 and Hsp90.
Topics: Animals; HSP90 Heat-Shock Proteins; Heat-Shock Proteins; Humans; Intrinsically Disordered Proteins; Mice; Molecular Chaperones; Phosphoproteins; Ubiquitins; alpha-Synuclein
PubMed: 36121476
DOI: 10.1007/s00401-022-02491-8 -
Biophysical Chemistry Jun 2021Mutations in the gene GBA, encoding glucocerebrosidase (GCase), are the highest genetic risk factor for Parkinson's disease (PD). GCase is a lysosomal glycoprotein... (Review)
Review
Mutations in the gene GBA, encoding glucocerebrosidase (GCase), are the highest genetic risk factor for Parkinson's disease (PD). GCase is a lysosomal glycoprotein responsible for the hydrolysis of glucosylceramide into glucose and ceramide. Mutations in GBA cause a decrease in GCase activity, stability and protein levels which in turn lead to the accumulation of GCase lipid substrates as well as α-synuclein (αS) in vitro and in vivo. αS is the main constituent of Lewy bodies found in the brain of PD patients and an increase in its levels was found to be associated with a decrease in GCase activity/protein levels in vitro and in vivo. In this review, we describe the reported biophysical and biochemical changes that GBA mutations can induce in GCase activity and stability as well as the current overview of the levels of GCase protein/activity, αS and lipids measured in patient-derived samples including post-mortem brains, stem cell-derived neurons, cerebrospinal fluid, blood and fibroblasts as well as in SH-SY5Y cells. In particular, we report how the levels of αS and lipids are affected by/correlated to significant changes in GCase activity/protein levels and which cellular pathways are activated or disrupted by these changes in each model. Finally, we review the current strategies used to revert the changes in the levels of GCase activity/protein, αS and lipids in the context of PD.
Topics: Glucosylceramidase; Humans; Lipids; Models, Molecular; Parkinson Disease; alpha-Synuclein
PubMed: 33832803
DOI: 10.1016/j.bpc.2020.106534 -
Current Protein & Peptide Science 2018Alpha synuclein (α-syn) belongs to a class of proteins which are commonly considered to play a detrimental role in neuronal survival. This assumption is based on the... (Review)
Review
Alpha synuclein (α-syn) belongs to a class of proteins which are commonly considered to play a detrimental role in neuronal survival. This assumption is based on the occurrence of a severe neuronal degeneration in patients carrying a multiplication of the α-syn gene (SNCA) and in a variety of experimental models, where overexpression of α-syn leads to cell death and neurological impairment. In these conditions, a higher amount of normally structured α-syn produces a damage, which is even worse compared with that produced by α-syn owning an abnormal structure (as occurring following point gene mutations). In line with this, knocking out the expression of α-syn is reported to protect from specific neurotoxins such as 1-methyl, 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP). In the present review we briefly discuss these well-known detrimental effects but we focus on findings showing that, in specific conditions α-syn is beneficial for cell survival. This occurs during methamphetamine intoxication which is counteracted by endogenous α-syn. Similarly, the dysfunction of the chaperone cysteine-string protein- alpha leads to cell pathology which is counteracted by over-expressing α-syn. In line with this, an increased expression of α-syn protects against oxidative damage produced by dopamine. Remarkably, when the lack of α-syn is combined with a depletion of β- and γ- synucleins, alterations in brain structure and function occur. This review tries to balance the evidence showing a beneficial effect with the bulk of data reporting a detrimental effect of endogenous α-syn. The specific role of α-syn as a chaperone protein is discussed to explain such a dual effect.
Topics: Animals; Apoptosis; Brain; Gene Expression; Humans; Nerve Degeneration; Neurons; Neuroprotection; Oxidative Stress; Signal Transduction; alpha-Synuclein
PubMed: 29150919
DOI: 10.2174/1389203718666171117110028 -
European Journal of Medicinal Chemistry Apr 2019A host of human diseases, including Parkinson's disease and Dementia with Lewy bodies, are suspected to be directly linked to protein aggregation. Amyloid protein... (Review)
Review
A host of human diseases, including Parkinson's disease and Dementia with Lewy bodies, are suspected to be directly linked to protein aggregation. Amyloid protein aggregates and oligomeric intermediates of α-synuclein are observed in synucleinopathies and considered to be mediators of cellular toxicity. Hence, α-synuclein has seen as one of the leading and most compelling targets and is receiving a great deal of attention from researchers. Nevertheless, there is no neuroprotective approach directed toward Parkinson's disease or other synucleinopathies so far. In this review, we summarize the available data concerning inhibitors of α-synuclein aggregation and their advancing towards clinical use. The compounds are grouped according to their chemical structures, providing respective insights into their mechanism of action, pharmacology, and pharmacokinetics. Overall, shared structure-activity elements are emerging, as well as specific binding modes related to the ability of the modulators to establish hydrophobic and hydrogen bonds interactions with the protein. Some molecules with encouraging in vivo data support the possibility of translation to the clinic.
Topics: Amyloidogenic Proteins; Drug Discovery; Humans; Protein Aggregation, Pathological; Structure-Activity Relationship; alpha-Synuclein
PubMed: 30743095
DOI: 10.1016/j.ejmech.2019.01.045 -
Biomolecules May 2015Mutations and duplication/triplication of the alpha-synuclein (αSyn)-coding gene have been found to cause familial Parkinson's disease (PD), while genetic polymorphisms... (Review)
Review
Mutations and duplication/triplication of the alpha-synuclein (αSyn)-coding gene have been found to cause familial Parkinson's disease (PD), while genetic polymorphisms in the region controlling the expression level and stability of αSyn have been identified as risk factors for idiopathic PD, pointing to the importance of wild-type (wt) αSyn dosage in the disease. Evidence that αSyn is present in the cerebrospinal fluid and interstitial brain tissue and that healthy neuronal grafts transplanted into PD patients often degenerate suggests that extracellularly-released αSyn plays a role in triggering the neurodegenerative process. αSyn's role in neurotransmission has been shown in various cell culture models in which the protein was upregulated or deleted and in knock out and transgenic animal, with different results on αSyn's effect on synaptic vesicle pool size and mobilization, αSyn being proposed as a negative or positive regulator of neurotransmitter release. In this review, we discuss the effect of αSyn on pre- and post-synaptic compartments in terms of synaptic vesicle trafficking, calcium entry and channel activity, and we focus on the process of exocytosis and internalization of αSyn and on the spreading of αSyn-driven effects due to the presence of the protein in the extracellular milieu.
Topics: Animals; Exocytosis; Humans; Parkinson Disease; Synaptic Transmission; alpha-Synuclein
PubMed: 25985082
DOI: 10.3390/biom5020865 -
Journal of Biochemistry Feb 2023The accumulation of protein aggregates as intracellular inclusions interferes with cellular protein homeostasis leading to protein aggregation diseases. Protein...
The accumulation of protein aggregates as intracellular inclusions interferes with cellular protein homeostasis leading to protein aggregation diseases. Protein aggregation results in the formation of several protein conformers including oligomers and fibrils, where each conformer has its own structural characteristic and proteotoxic potential. The present study explores the effect of alpha-synuclein (α-syn) conformers on the activity and spontaneous refolding of firefly luciferase. Of the different conformers, α-syn monomers delayed the inactivation of luciferase under thermal stress conditions and enhanced the spontaneous refolding of luciferase. In contrast, the α-syn oligomers and fibrils adversely affected luciferase activity and refolding, where the oligomers inhibited spontaneous refolding, whereas a pronounced effect on the inactivation of native luciferase was observed in the case of fibrils. These results indicate that the oligomers and fibrils of α-syn interfere with the refolding of luciferase and promote its misfolding and aggregation. The study reveals the differential propensities of various conformers of a pathologically relevant protein in causing inactivation, structural modifications and misfolding of other proteins, consequently resulting in altered protein homeostasis.
Topics: Humans; alpha-Synuclein; Parkinson Disease; Protein Aggregates; Protein Folding; Fireflies; Luciferases
PubMed: 36368019
DOI: 10.1093/jb/mvac095 -
Chemphyschem : a European Journal of... Mar 2021Parkinson's disease is a neurodegenerative disorder involving a functional protein, α-synuclein, whose primary function is related to vesicle trafficking. However,...
Parkinson's disease is a neurodegenerative disorder involving a functional protein, α-synuclein, whose primary function is related to vesicle trafficking. However, α-synuclein is prone to form aggregates, and these inclusions, known as Lewy bodies, are the hallmark of Parkinson's disease. α-synuclein can alter its conformation and acquire aggregating capacity, forming aggregates containing β-sheets. This protein's pathogenic importance is based on its ability to form oligomers that impair synaptic transmission and neuronal function by increasing membrane permeability and altering homeostasis, generating a deleterious effect over cells. First, we establish that oligomers interfere with the mechanical properties of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) membrane, as demonstrated by nanoindentation curves. In contrast, nanoindentation revealed that the α-synuclein monomer's presence leads to a much more resistant lipid bilayer. Moreover, the oligomers' interaction with cell membranes can promote lactate dehydrogenase (LDH) release, suggesting the activation of cytotoxic events.
Topics: Animals; Cell Line, Tumor; Cell Membrane; Hydrophobic and Hydrophilic Interactions; L-Lactate Dehydrogenase; Lipid Bilayers; Mice; Phosphatidylcholines; Protein Aggregates; Protein Multimerization; alpha-Synuclein
PubMed: 33482036
DOI: 10.1002/cphc.202000831