TNFα and α-synuclein fibrils differently regulate human astrocyte immune reactivity and impair mitochondrial respiration
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ABSTRACT:
PROVIDER: PRJNA701924 | ENA |
REPOSITORIES: ENA
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Project description:The overall goal was to identify changes in gene expression following treatment with aSYN F110 compared to control (untreated). Alpha-synuclein (αSYN) protein has been observed in reactive astrocytes in PD patients’ brains, raising the question of how αSYN, neuroinflammation, and astrocytes interact in PD pathogenesis. Here, we examined the cellular changes triggered by tumor necrosis factor alpha (TNFα) and different αSYN species in astrocytes derived from induced pluripotent stem cells. Human astrocytes treated with TNFα displayed a strong reactive pro-inflammatory phenotype with upregulation of pro-inflammatory gene networks, activation of the NF-kB pathway, and release of pro-inflammatory cytokines, whereas those treated with high molecular weight αSYN fibrils acquired a reactive antigen (cross-)presenting phenotype with upregulation of MHC genes and increased HLA-DR/DQ/DP and HLA-F molecules at the cell surface. Surprisingly, cell surface location of MHC proteins was abrogated by larger F110 fibrils polymorph, despite the upregulation of MHC genes. A proteomics investigation further confirmed a direct interaction between astrocytic MHC proteins and αSYN fibril peptides. Interestingly, TNFα and αSYN fibrils competed to drive the astrocyte immune reactive response. The astrocyte immune responses were accompanied by an impaired ATP-generating mitochondrial respiration, which was exacerbated in PD astrocytes containing a PARK2-variant. Our data provide evidence for astrocytic involvement in PD pathogenesis and reveal their complex immune reactive responses to exogenous stressors.
2021-02-16 | GSE166769 | GEO
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.
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Project description:The overall goal was to identify changes in gene expression following treatment with TNFa, monomeric, or fibril aSYN compared to control (untreated). Alpha-synuclein (αSYN) protein has been observed in reactive astrocytes in PD patients’ brains, raising the question of how αSYN, neuroinflammation, and astrocytes interact in PD pathogenesis. Here, we examined the cellular changes triggered by tumor necrosis factor alpha (TNFα) and different αSYN species in astrocytes derived from induced pluripotent stem cells. Human astrocytes treated with TNFα displayed a strong reactive pro-inflammatory phenotype with upregulation of pro-inflammatory gene networks, activation of the NF-kB pathway, and release of pro-inflammatory cytokines, whereas those treated with high molecular weight αSYN fibrils acquired a reactive antigen (cross-)presenting phenotype with upregulation of MHC genes and increased HLA-DR/DQ/DP and HLA-F molecules at the cell surface. Surprisingly, cell surface location of MHC proteins was abrogated by larger F110 fibrils polymorph, despite the upregulation of MHC genes. A proteomics investigation further confirmed a direct interaction between astrocytic MHC proteins and αSYN fibril peptides. Interestingly, TNFα and αSYN fibrils competed to drive the astrocyte immune reactive response. The astrocyte immune responses were accompanied by an impaired ATP-generating mitochondrial respiration, which was exacerbated in PD astrocytes containing a PARK2-variant. Our data provide evidence for astrocytic involvement in PD pathogenesis and reveal their complex immune reactive responses to exogenous stressors.
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Project description:Parkinson’s disease is characterized by the aggregation of the presynaptic protein α-synuclein and its deposition into pathologic Lewy bodies. While extensive research has been carried out on mediators of α-synuclein aggregation, molecular facilitators of α-synuclein disaggregation are still generally unknown. We investigated the role of molecular chaperones in both preventing and disaggregating α-synuclein oligomers and fibrils, with a focus on the mammalian disaggregase complex. Here, we show that overexpression of the chaperone Hsp110 is sufficient to reduce α-synuclein aggregation in a mammalian cell culture model. Additionally, we demonstrate that Hsp110 effectively mitigates α-synuclein pathology in vivo through the characterization of transgenic Hsp110 and double transgenic α-synuclein/Hsp110 mouse models. Unbiased analysis of the synaptic proteome of these mice revealed that overexpression of Hsp110 can override the protein changes driven by the α-synuclein transgene. Furthermore, overexpression of Hsp110 is sufficient to prevent endogenous α-synuclein templating and spread following injection of aggregated α-synuclein seeds into brain, supporting a role for Hsp110 in the prevention and/or disaggregation of α-synuclein pathology.
2020-05-26 | PXD016015 | Pride
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.
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