Neurodegeneration and Neuroinflammation are Linked, but Independent of α-Synuclein Inclusions, in a Seeding/Spreading Mouse Model of Parkinson’s Disease
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PROVIDER: PRJNA655395 | ENA |
REPOSITORIES: ENA
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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.
2020-11-02 | GSE155716 | GEO
Project description: Not available
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Project description:Neuroinflammatory processes are a prominent contributor to the pathology of Parkinson’s disease (PD), characterized by the progressive loss of dopaminergic neurons in the substantia nigra (SN) and deposits of α-synuclein aggregates. MLKL-mediated cell necroptosis might occur in the onset of PD and lead to neuronal dopaminergic degeneration. However, the link between α-synuclein, neuroinflammatory processes, and neurodegeneration in PD remains unclear. Here, our in vitro study indicated that inhibition of MLKL exerted a protective effect against 6-OHDA- and TNF-α-induced neuronal cell death. Furthermore, we created a mouse model (Tg-Mlkl-/-) with typical progressive Parkinson traits by crossbreeding SNCA A53T transgenic mice with MLKL knockout mice. Tg-Mlkl-/ mice displayed dramatically improved motor symptoms and reduced hyperphosphorylated α-synuclein expression. More data suggested that MLKL deficiency protected dopaminergic neurons, blocked neuronal cell death, and attenuated neuroinflammation by inhibiting the activation of the microglia and astrocytes. Single-cell RNA-seq analysis revealed reduced microglial cells and damped neuron death in the SN of the Tg-Mlkl-/- mice. Subcluster analysis identified a unique cell type-specific transcriptome profiling in the MLKL deficiency mice. Thus, MLKL represents a critical therapeutic target for reducing neuroinflammation and preventing dopaminergic neuron degeneration.
2023-12-14 | GSE197679 | GEO
Project description:Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by progressive paralysis resulting from specific degeneration of upper and lower motor neurons (MNs). Chronic neuroinflammation, mediated by activated microglia, is a hallmark of patients diagnosed with ALS, and correlates with disease pathogenesis. Protecting MNs, particularly from toxic insults caused by neuroinflammation, could lead to effective treatments of ALS patient. Here, we report a screening campaign identifying a series of pyrazolotriazines that cell-autonomously protect MNs against neuroinflammation. We demonstrate that these compounds inhibit Cyclin-dependent kinase 5 (CDK5) and Glycogen synthase kinase 3 (GSK3), and we use phospho-proteomics to show that neuroprotection is linked to alterations in microtubule dynamics.
2019-01-30 | PXD006452 | Pride
Project description:Although α-synucleinis implicated in the pathogenesis of Parkinson’s disease and related disorders, it remains unclear whether specific conformations or levels of α-synuclein assemblies are toxic and how they cause progressive loss of human dopaminergic neurons. To address this issue, we used iPSC-derived dopaminergic neurons with a-synuclein triplication or controls where endogenous α-synuclein was imprinted into synthetic or disease-relevant conformations. We used α-synuclein fibrils generated de novo or amplified from homogenates of brains affected with Parkinson’s disease (n=3) .We found that a 2.5-fold increase in α-synuclein levels in α-synuclein gene triplication neurons promoted seeded aggregation in a dose and time-dependent fashion, which was associated with a further increase in α-synuclein gene expression.Transcriptomic analysis and isogenic correction of α-synuclein triplication revealed that intraneuronal α-synuclein levels solely and sufficiently explained vulnerability to cell death.
2020-09-02 | GSE149632 | GEO
Project description:Althougha-synuclein is implicated in the pathogenesis of Parkinson’s disease and related disorders, it remains unclear whether specific conformations or levels ofa-synuclein assemblies are toxic and how they cause progressive loss of human dopaminergic neurons. To address this issue, we used iPSC-derived dopaminergic neurons with a-synuclein triplication or controls where endogenous a-synuclein was imprinted into synthetic or disease-relevant conformations. We used a-synuclein fibrils generated de novo or amplified from homogenates of brains affected with Parkinson’s disease (n=3) or multiple system atrophy (n=5). We found that a 2.5-fold increase in a-synuclein levels in a-synuclein gene triplication neurons promoted seeded aggregation in a dose and time-dependent fashion, which was associated with a further increase in a-synuclein gene expression. Progressive neuronal loss was observed only in a-synuclein triplication neurons seeded with brain-amplified fibrils. Transcriptomic analysis and isogenic correction of a-synuclein triplication revealed that intraneuronalalpha-synuclein levels solely and sufficiently explained vulnerability to neuronal death
2021-04-13 | GSE171999 | GEO
Project description:Abnormal accumulation of aggregated proteins and sustained microglial activation are important contributors of neurodegenerative process in neurological diseases. Recent studies have shown that aggregation-prone proteins, such as a-synuclein, the protein implicated in Parkinson’s disease (PD), are released from neuronal cells and thus present in the extracellular fluid, pointing to the possible paracrine effects of these proteins on microglial immune responses. However, the mechanism underlying the disease-associated microglial activation and the role of neuronal proteins in this process remain unknown. Here, we show that extracellular a-synuclein released from neuronal cells is an endogenous ligand of toll-like receptor 2 (TLR2) and activates microglia, which in turn induces neurodegeneration. Interaction between neuron-released a-synuclein and TLR2 and subsequent activation of the TLR2 signaling were demonstrated comprehensively by using computational modeling of signaling network and by the experimental validation in TLR2-deficient microglia both in vitro and in vivo. In contrast to the neuron-released a-synuclein, recombinant a-synuclein proteins, including monomer, oligomer, fibril, or nitrated forms, were not able to interact or activate TLR2, suggesting that neuronal cells have a mechanism of enriching specific forms of a-synuclein capable of activating TLR2 during the process of releasing this protein. Taken together, the results suggest that both neuron-released extracellular a-synuclein and TLR2 might be novel therapeutic targets for modifying neuroinflammation in PD and related neurodegenerative diseases. We collected culture media from differentiated SH-SY5Y cells overexpressing either human a-synuclein (alpha-SCM) or beta-galactosidase (LZCM) and treat these media to primary rat microglia at the concentration of a-synuclein of 1.1M. Transcriptome analyses with microglial cells treated with either aSCM or LZCM at two different time points, 6 h and 24 h.
2013-02-28 | E-GEOD-26532 | biostudies-arrayexpress
Project description:Neuroinflammation and accumulation of alphα-synuclein (α-syn) are core features of Parkinson disease (PD). We found that α-syn-induced neuroinflammation is driven by antigen presentation from CNS resident macrophages. A subset of these, border-associated macrophages (BAMs), expand and express genes and proteins necessary for immune cell recruitment, infiltration, and antigen presentation, whereas depletion of BAMs prevents neuroinflammation and neurodegeneration. These results point to a critical role for BAMs in initiating PD pathogenesis.
2021-06-20 | GSE178498 | GEO
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).
2022-10-02 | GSE214446 | GEO
Project description: Not available
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