Parkinson's disease genes VPS35 and EIF4G1 interact genetically and converge on alpha-synuclein
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ABSTRACT: Parkinson's disease (PD) is a common human neurodegenerative movement disorder. Studies of the genetic forms of PD have helped to reveal disease mechanisms. Functional interactions between some Parkinson's disease (PD) genes, like PINK1 and parkin, have been identified, but whether other ones interact remains elusive. Here we report an unexpected genetic interaction between two PD genes, VPS35 and EIF4G1. We provide evidence that EIF4G1 upregulation causes defects associated with protein misfolding. Expression of a sortilin protein rescues these defects, downstream of VPS35, suggesting a potential role for sortilins in PD. We also show interactions between VPS35, EIF4G1 and alpha-synuclein, a protein with a key role in the pathogenesis of both sporadic and familial PD. We extend our findings from yeast to an animal model and show these interactions are conserved in neurons. We also connect VPS35 impairments to neurodegeneration in alpha-synuclein transgenic mice. Our studies reveal unexpected genetic and functional interactions between two seemingly unrelated PD genes and functionally connect them to alpha-synuclein pathobiology in yeast, worms, and mouse. Finally, we provide a resource of candidate PD genes for future genetic and functional interrogation.
Project description:Parkinson's disease (PD) is a common human neurodegenerative movement disorder. Studies of the genetic forms of PD have helped to reveal disease mechanisms. Functional interactions between some Parkinson's disease (PD) genes, like PINK1 and parkin, have been identified, but whether other ones interact remains elusive. Here we report an unexpected genetic interaction between two PD genes, VPS35 and EIF4G1. We provide evidence that EIF4G1 upregulation causes defects associated with protein misfolding. Expression of a sortilin protein rescues these defects, downstream of VPS35, suggesting a potential role for sortilins in PD. We also show interactions between VPS35, EIF4G1 and alpha-synuclein, a protein with a key role in the pathogenesis of both sporadic and familial PD. We extend our findings from yeast to an animal model and show these interactions are conserved in neurons. We also connect VPS35 impairments to neurodegeneration in alpha-synuclein transgenic mice. Our studies reveal unexpected genetic and functional interactions between two seemingly unrelated PD genes and functionally connect them to alpha-synuclein pathobiology in yeast, worms, and mouse. Finally, we provide a resource of candidate PD genes for future genetic and functional interrogation. Ribosome profiling (RiboSeq) of wild type and VPS35 deletion yeast strains, with or without overexpression of the TIF4631 initiation factor
Project description:Detailed analysis of disease-affected tissue provides insight into molecular mechanisms contributing to pathogenesis. Substantia nigra, striatum and cortex are functionally connected with increasing degrees of alpha-synuclein pathology in Parkinson's disease. Functional and causal pathway analysis of gene expression and proteomic alterations in these three regions revealed pathways that correlated with deposition of alpha-synuclein. Microarray and RNAseq experiments revealed previously unidentified causal changes related to oligodendrocyte function and synaptic vesicle release and other changes were reflected across all brain regions. Importantly a subset of these changes were replicated in Parkinson's disease blood. Proteomic assessment revealed alterations in mitochondria and vesicular transport proteins that preceded gene gene expression changes indicating defects in translation and/or protein turnover. Our combined approach of proteomics, RNAseq and microarray analyses provides a comprehensive view of the molecular changes that accompany alpha-synculein pathology in Parkinson's disease, and may be instrumental in understanding and diagnosing Parkinson's disease progression. Substantia Nigra (3 normal, 3 PD), Striatum (6 normal, 6 PD), Cortex (5 normal, 5 PD), Cortex non-PD neurodegeneration (2 normal, 3 DLB). Note Sample X201264 was used both for Cortex normal and for Cortex nonPD normal
Project description:In order to investigate the effect of Alpha-Ketoglutarate (AKG) on p-α-synuclein in substantia nigra of Parkinson's disease (PD) model mice (C57BL/6), we profiled substantia nigra from wild-type (WT), AAV-α-synuclein (α-Syn), AKG and α-Syn-AKG in male mice by RNA sequencing (RNA-seq).
Project description:Sass2009 - Approach to an
α-synuclein-based BST model of Parkinson's disease
This model is described in the article:
A pragmatic approach to
biochemical systems theory applied to an alpha-synuclein-based
model of Parkinson's disease.
Sass MB, Lorenz AN, Green RL,
Coleman RA.
J. Neurosci. Methods 2009 Apr; 178(2):
366-377
Abstract:
This paper presents a detailed systems model of Parkinson's
disease (PD), developed utilizing a pragmatic application of
biochemical systems theory (BST) intended to assist
experimentalists in the study of system behavior. This approach
utilizes relative values as a reasonable initial estimate for
BST and provides a theoretical means of applying numerical
solutions to qualitative and semi-quantitative understandings
of cellular pathways and mechanisms. The approach allows for
the simulation of human disease through its ability to organize
and integrate existing information about metabolic pathways
without having a full quantitative description of those
pathways, so that hypotheses about individual processes may be
tested in a systems environment. Incorporating this method, the
PD model describes alpha-synuclein aggregation as mediated by
dopamine metabolism, the ubiquitin-proteasome system, and
lysosomal degradation, allowing for the examination of dynamic
pathway interactions and the evaluation of possible toxic
mechanisms in the aggregation process. Four system
perturbations: elevated alpha-synuclein aggregation, impaired
dopamine packaging, increased neurotoxins, and alpha-synuclein
overexpression, were analyzed for correlation to qualitative PD
system hypotheses present in the literature, with the model
demonstrating a high level of agreement with these hypotheses.
Additionally, various PD treatment methods, including levadopa
and monoamine oxidase inhibition (MAOI) therapy, were applied
to the disease models to examine their effects on the system.
Future additions and refinements to the model may further the
understanding of the emergent behaviors of the disease, helping
in the identification of system sensitivities and possible
therapeutic targets.
This model is hosted on
BioModels Database
and identified by:
BIOMD0000000575.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.
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.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.
Project description:The pre-synaptic protein α-synuclein is a key player in the pathogenesis of Parkinson's disease. Together with accumulation and missfolding of α-synuclein protofibrils serve as seed structures for the aggregation of numerous proteins in the cytoplasm of neuronal cells, the so-called Lewy bodies. Furthermore, missense mutations in the SNCA gene and gene multiplications lead to autosomal dominant forms of familiar PD. However, so far the exact biological role of α-synuclein in normal brain is elusive. To gain more insights into the biological function of this protein we monitored whole genome expression changes in dopaminergic neuroblastoma cells (SH-SY5Y) caused by a 90% reduction of α-synuclein by RNA interference. Keywords: whole genome expression changes through the loss of α-synuclein
Project description:Hallacli E, Kayatekin C, Nazeen S, Wang XH, Sheinkopf Z, Sathyakumar S, Sarkar S, Jiang X, Dong X, Di Maio R, Wang W, Keeney MT, Felsky D, Sandoe J, Vahdatshoar A, Udeshi ND, Mani DR,Carr SA, de Jager P, Myers CL, Lindquist S, Greenmyre TJ, Bartel DP, Feany MB, Sunyaev S, Chung CY and Khurana V. Alpha-synuclein, Syn, is a conformationally plastic protein that reversibly binds to cellular membranes. It aggregates and is genetically linked to Parkinson's disease (PD). Here, we show that Syn directly modulates Processing-bodies (P-bodies), membraneless organelles that function in mRNA turnover and storage. The N-terminus of alpha Syn, but not other synucleins, dictates mutually exclusive binding either to cellular membranes or to P-bodies in the cytosol. Syn binds directly to multiple decapping proteins in close proximity on the Edc4 scaffold. As Syn pathologically accumulates, aberrant interaction with Edc4 occurs at the expense of physiologic decapping-module interactions. mRNA-decay kinetics within PD-relevant pathways are consequently disrupted in PD patient neurons and brain. Genetic modulation of P-body components alters Syn toxicity, and human genetic analysis lends support to the disease-relevance of these interactions. Beyond revealing an unexpected aspect of Syn function and pathology, our data highlight the versatility of conformationally plastic proteins with high intrinsic disorder.
Project description:A major barrier to research on Parkinson’s disease (PD) is inaccessibility of diseased tissue for study. One solution is to derive induced pluripotent stem cells (iPSCs) from patients with PD and differentiate them into neurons affected by disease. We created an iPSC model of PD caused by triplication of SNCA encoding α-synuclein. α-Synuclein dysfunction is common to all forms of PD, and SNCA triplication leads to fully penetrant familial PD with accelerated pathogenesis. After differentiation of iPSCs into neurons enriched for midbrain dopaminergic subtypes, those from the patient contain double α-synuclein protein compared to those from an unaffected relative, precisely recapitulating the cause of PD in these individuals. A measurable biomarker makes this model ideal for drug screening for compounds that reduce levels of α-synuclein, and for mechanistic experiments to study PD pathogenesis. This gene expression microarray study was carried out as part of the validation process for demonstrating that the generated iPSC lines are pluripotent. 5 samples were analysed: two clonal iPSC lines from each of two genotypes (four in total; AST denoting alpha-synuclein triplication and NAS denoting normal alpha-synuclein), a human embryonic stem cell line (SHEF4). All cultured in self-renewal conditions, mTeSR1
Project description:A key process of neurodegeneration in Parkinson's disease (PD) is the transneuronal spreading of alpha-synuclein. Alpha-synuclein is a presynaptic protein that is implicated in the pathogenesis of PD and other synucleinopathies, where it forms, upon intracellular aggregation, pathological inclusions. Other hallmarks of PD include neurodegeneration and microgliosis in susceptible brain regions. Whether it is primarily transneuronal spreading of a-synuclein particles, inclusion formation, or other mechanisms, such as inflammation, that cause neurodegeneration in PD is unclear. We used spreading/aggregation of alpha-synuclein induced by intracerebral injection of a-synuclein preformed fibrils into the mouse brain to address this question. We performed quantitative histological analysis for a-synuclein inclusions, neurodegeneration, and microgliosis in different brain regions, and a gene expression profiling of the ventral midbrain, at two different timepoints after disease induction. We observed significant neurodegeneration and microgliosis in brain regions not only with, but also withouta-synuclein inclusions. We also observed prominent microgliosis in injured brain regions that did not correlate with neurodegeneration nor with inclusion load. In longitudinal gene expression profiling experiments, we observed early and unique alterations linked to microglial mediated inflammation that preceded neurodegeneration, indicating an active role of microglia in inducing neurodegeneration. Our observations indicate that a-synuclein inclusion formation is not the major driver in the early phases of PD-like neurodegeneration, but that diffusible, oligomeric a-synuclein species, which induce unusual microglial reactivity, play a key role in this process.