Aggregation of α-synuclein scaffolds RNA G-quadruplexes assembly leading to progressive neurodegeneration
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ABSTRACT:
PROVIDER: PRJNA980607 | ENA |
REPOSITORIES: ENA
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Project description:Synucleinopathies are triggered by the aggregation of α-synuclein (αSyn), leading to progressive neurodegeneration. However, the intracellular mechanism of αSyn aggregation remains unclear. Here we show that assembly of RNA G-quadruplexes (rG4s) form scaffolds for αSyn aggregation, contributing to neurodegeneration. Purified αSyn binds rG4s directly through the N-terminus. rG4 itself undergoes phase separation and assembly by Ca2+, accelerating the sol-gel phase transition of αSyn. In αSyn preformed fibrils (PFF)-treated neurons, rG4s assembly composed of synaptic mRNAs co-aggregates with αSyn upon Ca2+ excess influx into cytoplasm, eliciting synaptic dysfunction. Artificial assembly of rG4s using an optogenetic approach evokes αSyn aggregation and neuronal dysfunction. Administration of 5-aminolevulinic acid (5-ALA), a prodrug of protoporphyrin IX (PpIX) that prevents phase separation of rG4s, attenuating αSyn aggregation, neurodegeneration, and progressive motor deficits in PFF-injected synucleinopathy mice. Together, assembly of rG4s due to dysregulation of intracellular Ca2+ homeostasis accelerates αSyn phase transition and aggregation may contribute to pathogenesis of synucleinopathies.
2023-07-18 | GSE234238 | GEO
Project description:Aggregation of α-synuclein may trigger the development of synucleinopathies, a progressive neurodegenerative disease such as Parkinson's disease and Dementia with Lewy bodies. We demonstrate RNA initiates α-synuclein phase transition in vitro, however, RNA binding ability and its motif remain unclear. Here, we indicate purified human α-synuclein protein preferentially binds to guanine-rich RNA sequences by RNA Bind-N-Seq using a pool of random 24-mer RNA oligonucleotides in vitro. Importantly, these hit motifs were required consecutive guanines not random, suggesting that RNA G-quadruplexes binds to α-synuclein. We also confirmed that GC content and skew of α-synuclein-enriched RNA sequences were similar to that of BG4 (G-quadruplex antibody)-enriched RNA sequences. Taken together, these data suggest that α-synuclein binds to RNA-formed G-quadruplex.
2023-07-17 | GSE235418 | GEO
Project description:Abnormal neuronal aggregation of a-synuclein is implicated in the development of Parkinson’s disease. Glial cells also show extensive a-synuclein pathology and are thought to contribute to disease progression. However, the mechanism that produces the glial a-synuclein pathology and the interaction between neurons and glia in the disease-inflicted microenvironment remain unknown. Here, we show that in neuronal cells misfolded a-synuclein proteins are selectively translocated into vesicles, leading to exocytosis of the aggregated forms. More importantly, our data demonstrate that astrocytes take up the neuron-derived a-synuclein aggregates and produce a-synuclein inclusions similar to the ones found in human brains. This uptake is paralleled by changes in the gene expression profile reflecting an inflammatory response. These results suggest that astroglial a-synuclein pathology is produced by cell-to-cell transmission of neuronal a-synuclein aggregates. This transmission step is thus an important mediator of pathogenic glial responses and could qualify as a new therapeutic target. To determine how astrocytes respond to extracellular a-synuclein, gene expression profiles were established and analyzed for nearly 22,000 rat genes using the Illumina RatRef-12 Expression BeadChip. Total RNA was isolated from astrocytes exposed for 6h or 24h to conditioned medium from cultures of a-synuclein or lacZ expressing cells.
2010-01-11 | E-GEOD-11574 | biostudies-arrayexpress
Project description:Morris2009 - α-Synuclein aggregation
variable temperature and pH
This model is described in the article:
Alpha-synuclein aggregation
variable temperature and variable pH kinetic data: a
re-analysis using the Finke-Watzky 2-step model of nucleation
and autocatalytic growth.
Morris AM, Finke RG.
Biophys. Chem. 2009 Mar; 140(1-3):
9-15
Abstract:
The aggregation of proteins is believed to be intimately
connected to many neurodegenerative disorders. We recently
reported an "Ockham's razor"/minimalistic approach to analyze
the kinetic data of protein aggregation using the Finke-Watzky
(F-W) 2-step model of nucleation (A-->B, rate constant k(1))
and autocatalytic growth (A+B-->2B, rate constant k(2)).
With that kinetic model we have analyzed 41 representative
protein aggregation data sets in two recent publications,
including amyloid beta, alpha-synuclein, polyglutamine, and
prion proteins (Morris, A. M., et al. (2008) Biochemistry 47,
2413-2427; Watzky, M. A., et al. (2008) Biochemistry 47,
10790-10800). Herein we use the F-W model to reanalyze protein
aggregation kinetic data obtained under the experimental
conditions of variable temperature or pH 2.0 to 8.5. We provide
the average nucleation (k(1)) and growth (k(2)) rate constants
and correlations with variable temperature or varying pH for
the protein alpha-synuclein. From the variable temperature
data, activation parameters DeltaG(double dagger),
DeltaH(double dagger), and DeltaS(double dagger) are provided
for nucleation and growth, and those values are compared to the
available parameters reported in the previous literature
determined using an empirical method. Our activation parameters
suggest that nucleation and growth are energetically similar
for alpha-synuclein aggregation (DeltaG(double
dagger)(nucleation)=23(3) kcal/mol; DeltaG(double
dagger)(growth)=22(1) kcal/mol at 37 degrees C). From the
variable pH data, the F-W analyses show a maximal k(1) value at
pH approximately 3, as well as minimal k(1) near the
isoelectric point (pI) of alpha-synuclein. Since solubility and
net charge are minimized at the pI, either or both of these
factors may be important in determining the kinetics of the
nucleation step. On the other hand, the k(2) values increase
with decreasing pH (i.e., do not appear to have a minimum or
maximum near the pI) which, when combined with the k(1) vs. pH
(and pI) data, suggest that solubility and charge are less
important factors for growth, and that charge is important in
the k(1), nucleation step of alpha-synuclein. The chemically
well-defined nucleation (k(1)) rate constants obtained from the
F-W analysis are, as expected, different than the 1/lag-time
empirical constants previously obtained. However, k(2)x[A](0)
(where k(2) is the rate constant for autocatalytic growth and
[A](0) is the initial protein concentration) is related to the
empirical constant, k(app) obtained previously. Overall, the
average nucleation and average growth rate constants for
alpha-synuclein aggregation as a function of pH and variable
temperature have been quantitated. Those values support the
previously suggested formation of a partially folded
intermediate that promotes aggregation under high temperature
or acidic conditions.
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2024-09-02 | BIOMD0000000566 | BioModels
Project description:Parkinson’s Disease (PD) is a common neurodegenerative disorder affecting millions of people worldwide for which there are only symptomatic therapies. Small molecules able to target key pathological processes in PD have emerged as interesting options for modifying disease progression. We have previously shown that a (poly)phenol-enriched fraction (PEF) of Corema album L. leaf extract modulates central events in PD pathogenesis, namely α-synuclein (αSyn) toxicity, aggregation and clearance. PEF was now subjected to a bio-guided fractionation with the aim of identifying the critical bioactive compound. We identified genipin, an iridoid, which relieves αSyn toxicity and aggregation. Furthermore, genipin promotes metabolic alterations and modulates lipid storage and endocytosis. Importantly, genipin was able to prevent the motor deficits caused by the expression of αSyn-GFP in a Drosophila melanogaster model of PD. These findings open new avenues for the exploitation of genipin for PD therapeutics.
2023-04-06 | GSE226744 | GEO
Project description:Several genetic and environmental risk factors for Parkinson’s disease have been identified that converge on mitochondria as central elements in the disease process. However, the mechanisms by which mitochondrial dysfunction contributes to neurodegeneration remain incompletely understood. Non-bioenergetic pathways of the mitochondria are increasingly appreciated, but confounding bioenergetic defects are a major barrier to experimental validation. Here, we describe a novel bioenergetics-independent mechanism by which mild mitochondrial protein import stress augments neurodegeneration. We induced this mitochondrial protein import stress in an established mouse model of Parkinson’s disease expressing the A53T mutated form of human alpha-synuclein (SNCA). Mice with import stress in addition to the A53T mutation demonstrated increased size of SNCA aggregates, co-aggregation of mitochondrial preproteins with SNCA protein, worsened neurodegeneration and changes in gene expression, as determined by whole-transcriptome RNA-sequencing analysis of the forebrain (striatum), cerebellum, spinal cord, as well as heart and skeletal muscle.
2023-10-08 | GSE236975 | GEO
Project description:Accumulation of aggregated α-synuclein into Lewy bodies is thought to contribute to the onset and progression of dopaminergic neuron degeneration in Parkinson’s disease (PD) and related disorders. Although protein aggregation is associated with perturbation of proteostasis, how α-synuclein aggregation affects the brain proteome and signaling remains uncertain. In a mouse model of α-synuclein aggregation, 6% of 6,215 proteins and 1.6% of 8,183 phosphopeptides changed in abundance, indicating conservation of proteostasis and phosphorylation signaling. The proteomic analysis confirmed changes in abundance of proteins that regulate dopamine synthesis and transport, synaptic activity and integrity, and unearthed changes in mRNA binding, processing and protein translation. Phosphorylation signaling changes centered on axonal and synaptic cytoskeletal organization and structural integrity. Proteostatic responses included a significant increase in the levels of Lmp7, a component of the immunoproteasome. Increased Lmp7 levels and activity were also quantified in postmortem human brains with PD and dementia with Lewy bodies. Functionally, the immunoproteasome degrades α-synuclein aggregates and generates potentially antigenic peptides. Expression and activity of the immunoproteasome may represent testable targets to induce adaptive responses that maintain proteome integrity and modulate immune responses in protein aggregation disorders.
2018-05-18 | PXD009647 | Pride
Project description:Mitochondrial protein import stress augments alpha-synuclein aggregation and neurodegeneration independent of bioenergetics
| PRJNA993235 | ENA
Project description:Abnormal neuronal aggregation of a-synuclein is implicated in the development of Parkinson’s disease. Glial cells also show extensive a-synuclein pathology and are thought to contribute to disease progression. However, the mechanism that produces the glial a-synuclein pathology and the interaction between neurons and glia in the disease-inflicted microenvironment remain unknown. Here, we show that in neuronal cells misfolded a-synuclein proteins are selectively translocated into vesicles, leading to exocytosis of the aggregated forms. More importantly, our data demonstrate that astrocytes take up the neuron-derived a-synuclein aggregates and produce a-synuclein inclusions similar to the ones found in human brains. This uptake is paralleled by changes in the gene expression profile reflecting an inflammatory response. These results suggest that astroglial a-synuclein pathology is produced by cell-to-cell transmission of neuronal a-synuclein aggregates. This transmission step is thus an important mediator of pathogenic glial responses and could qualify as a new therapeutic target.
2010-01-12 | GSE11574 | GEO
Project description:Accumulation of aggregated α-synuclein into Lewy bodies is thought to contribute to the onset and progression of dopaminergic neuron degeneration in Parkinson’s disease (PD) and related disorders. Although protein aggregation is associated with perturbation of proteostasis, how α-synuclein aggregation affects the brain proteome and signaling remains uncertain. In a mouse model of α-synuclein aggregation, 6% of 6,215 proteins and 1.6% of 8,183 phosphopeptides changed in abundance, indicating conservation of proteostasis and phosphorylation signaling. The proteomic analysis confirmed changes in abundance of proteins that regulate dopamine synthesis and transport, synaptic activity and integrity, and unearthed changes in mRNA binding, processing and protein translation. Phosphorylation signaling changes centered on axonal and synaptic cytoskeletal organization and structural integrity. Proteostatic responses included a significant increase in the levels of Lmp7, a component of the immunoproteasome. Increased Lmp7 levels and activity were also quantified in postmortem human brains with PD and dementia with Lewy bodies. Functionally, the immunoproteasome degrades α-synuclein aggregates and generates potentially antigenic peptides. Expression and activity of the immunoproteasome may represent testable targets to induce adaptive responses that maintain proteome integrity and modulate immune responses in protein aggregation disorders.
2018-05-18 | PXD009717 | Pride