α-Synuclein Translocates To The Nucleus To Activate Retinoic Acid- Dependent Gene Transcription
Ontology highlight
ABSTRACT: α-Synuclein (α-Syn) is a protein implicated in the pathogenesis of Parkinson’s disease (PD). It is primarily cytosolic and reversibly interacts with cell membranes. α-Syn also occurs in the nucleus, however, the mechanisms involved in its nuclear localization are poorly understood. We analyzed alterations in gene expression following induced α-Syn expression in SH-SY5Y cells. Analysis for upstream regulators pointed at alterations in transcription activity of retinoic acid receptors (RAR)s and additional nuclear receptors. We show that α-Syn binds RA and translocates to the nucleus to selectively enhance gene transcription. Nuclear translocation of α-Syn is regulated by calreticulin, in a leptomycin-B independent mechanism. Importantly, nuclear translocation of α-Syn following RA treatment enhances its toxicity in cultured neurons and the expression levels of PD-associated genes, among which are two familial PDassociated genes, ATPase cation transporting 13A2 (ATP13A2) and PTEN-induced kinase 1 (PINK1). The results link a physiological role for α-Syn in the regulation of RAmediated gene transcription and its toxicity in the synucleinopathies.
Project description:LC-MS/MS analyses were performed on soluble alpha-Syn purified from PD and various alpha-Synucleinopathies to systematically explore the landscape of post-translational modifications (PTMs) on soluble alpha-Syn, leading to the identification of a large number of novel alpha-Syn PTMs.
Project description:LC-MS/MS analyses were performed on soluble alpha-Syn purified from PD and various alpha-Synucleinopathies to systematically explore the landscape of post-translational modifications (PTMs) on soluble alpha-Syn, leading to the identification of a large number of novel alpha-Syn PTMs.
Project description:Parkinson’s disease (PD) is a prevalent neurodegenerative disorder that is characterized by the selective loss of midbrain dopamine (DA)-producing neurons and the formation of α-synuclein (α-syn)-containing inclusions named Lewy bodies (LBs). Here, we report that the loss of glucocerebrosidase (GCase), coupled with α-syn overexpression, result in substantial accumulation of detergent-resistant α-syn aggregates and Lewy body-like inclusions (LBLIs) in human midbrain-like organoids (hMLOs). These LBLIs exhibit a highly similar structure to PD-associated LBs, by displaying a spherically symmetric morphology with an eosinophilic core, and containing α-syn and ubiquitin. Importantly, hMLOs generated from PD patient-derived inducible pluripotent stem cells (iPSCs) harboring SNCA triplication also exhibit subsequent degeneration of DA neurons and LBLI formation upon chronic GCase inhibitor treatment. Taken together, our hMLOs harbouring two major PD risk factors (GCase deficiency and overproduced α-syn) successfully recapitulate major pathophysiological signatures of the disease, and highlight the broad utility of brain organoid technology in modeling human neurodegenerative diseases.
Project description:Increased levels of the protein alpha-synuclein (α-syn) are associated with the development of neurodegenerative diseases like Parkinson's disease (PD). In physiological conditions, α-syn modulates synaptic plasticity, neurogenesis and neuronal survival. Here, we used a PD patient specific midbrain organoid model derived from induced pluripotent stem cells harboring a triplication in the SNCA gene to study PD-associated phenotypes. The model recapitulates the two main hallmarks of PD, which are α-syn aggregation and loss of dopaminergic neurons. Additionally, impairments in astrocyte differentiation were detected. Transcriptomics data indicate that synaptic function is impaired in PD specific midbrain organoids. This is further confirmed by alterations in synapse number and electrophysiological activity. We found that synaptic decline precedes neurodegeneration. Finally, this study substantiates that patient specific midbrain organoids allow a personalized phenotyping, which make them an interesting tool for precision medicine and drug discovery. However, its pathogenic accumulation and aggregation results in toxicity and neurodegeneration.
Project description:Kuznetsov2016(II) - α-syn aggregation
kinetics in Parkinson's
This theoretical model uses 2-step Finke-Watzky (FW) kinetics
todescribe the production, misfolding, aggregation, transport and
degradation of α-syn that may lead to Parkinson's Disease
(PD). Deregulated α-syn degradation is predicted to be
crucialfor PD pathogenesis.
This model is described in the article:
What can trigger the onset
of Parkinson's disease - A modeling study based on a
compartmental model of α-synuclein transport and aggregation in
neurons.
Kuznetsov IA, Kuznetsov AV.
Math Biosci 2016 Aug; 278: 22-29
Abstract:
The aim of this paper is to develop a minimal model
describing events leading to the onset of Parkinson's disease
(PD). The model accounts for α-synuclein (α-syn) production in
the soma, transport toward the synapse, misfolding, and
aggregation. The production and aggregation of polymeric α-syn
is simulated using a minimalistic 2-step Finke-Watzky model. We
utilized the developed model to analyze what changes in a
healthy neuron are likely to lead to the onset of α-syn
aggregation. We checked the effects of interruption of α-syn
transport toward the synapse, entry of misfolded (infectious)
α-syn into the somatic and synaptic compartments, increasing
the rate of α-syn synthesis in the soma, and failure of α-syn
degradation machinery. Our model suggests that failure of α-syn
degradation machinery is probably the most likely cause for the
onset of α-syn aggregation leading to PD.
This model is hosted on
BioModels Database
and identified by:
BIOMD0000000615.
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quantitative kinetic models.
To the extent possible under law, all copyright and related or
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Project description:Abnormal intraneuronal accumulation of soluble and insoluble alpha-synuclein (alpha-Syn) is one of the main pathological hallmarks of synucleinopathies, such as Parkinson’s disease (PD). It has been well- documented that the reversible liquid-liquid phase separation of alpha-Syn can modulate synaptic vesicle condensates at the presynaptic terminals. However, alpha-Syn can also form liquid-like droplets that may convert into amyloid-enriched hydrogels or fibrillar polymorphs under stressful conditions. To advance our understanding on the mechanisms underlying alpha-Syn phase transition, we employed a series of unbiased proteomic analyses and found that actin and actin regulators are part of the alpha-Syn interactome. We focused on Neural Wiskott-Aldrich syndrome protein (N-WASP) because of its association with a rare early-onset familial form of PD. In cultured cells, we demonstrate that N-WASP undergoes phase separation and can be recruited to synapsin-1 liquid-like droplets, whereas it is excluded from alpha-Syn/synapsin-1 condensates. Consistently, we provide evidence that wsp-1/WASL loss of function (lof) alters the number and dynamics of alpha-Syn inclusions in the nematode Caenorhabditis elegans. Together, our findings indicate that N-WASP expression may create permissive conditions that promote alpha-Syn condensates and their potentially deleterious conversion into toxic species.
Project description:Intracellular accumulation of a-synuclein (a-syn) and formation of Lewy bodies are neuropathological characteristics of Parkinson‘s disease (PD), related a-synucleinopathies, and other neurodegenerative diseases. Recent evidence suggests that oligomerization and spreading of a-syn from neuron to neuron are key events contributing to the development of PD. To directly visualize and characterize a-syn oligomerization and spreading in vivo, we generated two independent conditional transgenic mouse models based on a-syn protein complementation assays using both split Gaussia luciferase and split Venus YFP. These inducible, neuron-specific transgenic mice allow to directly assess the quantity and subcellular distribution of a-syn oligomers in vivo. Using these innovative mouse models we demonstrate an age dependent accumulation of a specific subtype of a-syn oligomers and their synaptic localization in vivo. We provide in vivo evidence that although a-syn is found throughout neurons a-syn oligomerization takes place at the presynapse. Furthermore, our new mouse models provide strong evidence for a long distance transsynaptic cell-to-cell transfer of de novo generated a-syn oligomers in vivo.
Project description:Alpha-synuclein (α-syn) aggregation and immune activation represent hallmark pathological events in Parkinson’s disease (PD). The PD-associated immune response encompasses both brain and peripheral immune cells, although little is known about the immune proteins relevant for such response. We propose that the upregulation of CD163 observed in blood monocytes and in the responsive microglia in the PD patients is a protective mechanism in the disease. To investigate this, we used the PD model based on intrastriatal injections of murine α-syn pre-formed fibrils (PFF) in CD163 knockout (KO) mice and wild-type littermates. CD163KO females revealed an impaired and differential early immune response to α-syn pathology as revealed by immunohistochemical and transcriptomic analysis. After 6 months, CD163KO females showed an exacerbated immune response and α-syn pathology, which ultimately led to a dopaminergic neurodegeneration of greater magnitude. These findings support a novel, sex-dimorphic neuroprotective role for CD163 during α-syn-induced neurodegeneration.
Project description:Parkinson's disease is the second most common neurodegenerative disorder, whose characteristic pathology involves progressive loss of dopaminergic neurons and formation of Lewy bodies(LBs) in the substantia nigra(SN). Aggregated and misfolded α-synuclein(α-syn) is the major constituent of LBs. As the newly discovered pathway of renin-angiotensin system (RAS), Angiotensin-(1-7)(Ang-(1-7)) and its receptor Mas have attracted increasing attentions for their correlation with PD progression, but underlying mechanisms remain not very clear. Based on the above, this study established PD models of mice and primary dopaminergic neurons with overexpression of α-syn, then discussed the effect of Ang-(1-7)/Mas on these models combined with downstream lncRNA and miRNA. The findings show that Ang-(1-7) alleviates behavioral disorders, rescues dopaminergic neurons loss and lowers α-syn expression in the SN of hα-syn(A53T) overexpressed PD mice. We also discover that Ang-(1-7) decreases the level of α-syn and apoptosis in the hα-syn(A53T) overexpressed dopaminergic neurons through NEAT1/miR-153-3p axis. Moreover, miR-153-3p expression in peripheral blood is found negatively correlated with that of α-syn. These results not only uncovered the significance and related mechanisms of Ang-(1-7)/Mas on α-syn pathology, but also throwed a new light upon miR-153-3p and NEAT1 as biomarkers and therapeutic targets in PD.
Project description:Objective: Parkinson's disease (PD) is part of a common type of neurodegenerative disease. AVE0991, a non-peptide analogue of Ang-(1-7), by which the progression of PD has been discovered to be ameliorated, but the specific mechanism whereby AVE0991 modulates the progression of PD remains unclear. Materials and Methods: During the study, the mice overexpressing of human α-syn(A53T) were established to simulate PD pathology, and we also constructed an in vitro model of mouse dopaminergic neurons overexpressing hα-syn(A53T). The [18F] FDG-PET/CT method was also employed to assess FDG uptake in human α-syn(A53T) overexpressing mice. Level of Lnc HOTAIRM1, miR-223-3p were detected via RT-qPCR. Flow cytometry was deployed to assay cell apoptosis. Results: AVE0991 improved behavior disorder and decreased α-syn expression in the substantia nigra in mice with Parkinson's disease. AVE0991 inhibited apoptosis of dopaminergic neurons overexpressing hα-syn(A53T) by LncRNA HOTAIRM1. MiR-223-3p binds to HOTAIRM1 as a ceRNA and directly targets α-syn. Conclusion: The angiotensin-(1–7) analogue AVE0991 targeted the HOTAIRM1/miR-223-3p axis to degrade α-synuclein in PD mice, and showed neuroprotection in vitro.