Modulation of Neurodegeneration by CSFR1 Inhibition in an a-synuclein model of DLB/PD
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE255025 | GEO | 2024/09/30
REPOSITORIES: GEO
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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:Aging is the predominant risk factor for neurodegenerative diseases. One key phenotype as brain ages is the aberrant innate immune response characterized by proinflammation. However, the molecular mechanisms underlying aging-associated proinflammation are poorly defined. Whether chronic inflammation plays a causal role in cognitive decline in aging and neurodegeneration has not been established. Here we established a mechanistic link between chronic inflammation and aging microglia, and demonstrated a causal role of aging microglia in neurodegenerative cognitive deficits. Expression of microglial SIRT1 reduces with the aging of microglia. Genetic reduction of microglial SIRT1 elevates IL-1β selectively, and exacerbates cognitive deficits in aging and in transgenic mouse models of frontotemporal dementia (FTD). Interestingly, the selective activation of IL-1β transcription by SIRT1 deficiency is likely mediated through hypomethylating the proximal promoter of IL-1β. Consistent with our findings in mice, selective hypomethylation of IL-1β at two CpG sites are found in normal aging humans and demented patients with tauopathy. Our findings reveal a novel epigenetic mechanism in aging microglia that contributes to cognitive deficits in neurodegenerative diseases. Study of changes related to alterations of SIRT1 levels in microglia of young and aged animals and in models of neurodegenerative dementia
2014-10-01 | E-GEOD-56452 | biostudies-arrayexpress
Project description:Microglia are the resident immune cells of the brain and have been implicated in mechanisms essential for cognitive functions. Down syndrome (DS), the most frequent cause of genetic intellectual disability, is caused by the presence of a supernumerary chromosome 21, which contains genes essential for the function of the immune system. Here, we investigated the presence of microglial alterations and their implication for cognitive impairment in the Dp(16) mouse model of DS. In the hippocampus of Dp(16) mice and individuals with DS, we found microglial morphology indicative of an activated state. Accordingly, we found increased levels of pro-inflammatory cytokines and altered interferon signaling in Dp(16) mice. In addition, Dp(16) mice showed decreased dendritic spine density and cognitive deficits. Remarkably, depletion of defective microglia by PLX3397 treatment or rescue of the microglia activated state by the commonly used anti-inflammatory drug acetaminophen fully rescued dendritic-spine density and cognitive deficits in Dp(16) mice. Our data suggest an involvement of microglia in the cognitive impairment of DS animals and identify a new therapeutic approach for the potential rescue of cognitive disabilities in individuals with DS.
2020-09-22 | PXD015113 | Pride
Project description:Microglia are the resident immune cells of the brain and have been implicated in mechanisms essential for cognitive functions. Down syndrome (DS), the most frequent cause of genetic intellectual disability, is caused by the presence of a supernumerary chromosome 21, which contains genes essential for the function of the immune system. Here, we investigated the presence of microglial alterations and their implication for cognitive impairment in the Dp(16) mouse model of DS. In the hippocampus of Dp(16) mice and individuals with DS, we found microglial morphology indicative of an activated state. Accordingly, we found increased levels of pro-inflammatory cytokines and altered interferon signaling in Dp(16) mice. In addition, Dp(16) mice showed decreased dendritic spine density and cognitive deficits. Remarkably, depletion of defective microglia by PLX3397 treatment or rescue of the microglia activated state by the commonly used anti-inflammatory drug acetaminophen fully rescued dendritic-spine density and cognitive deficits in Dp(16) mice. Our data suggest an involvement of microglia in the cognitive impairment of DS animals and identify a new therapeutic approach for the potential rescue of cognitive disabilities in individuals with DS.
2020-09-22 | PXD015148 | Pride
Project description:BACKGROUND: Synucleinopathy disorders are characterized by aggregates of α-synuclein (α-syn), which engage microglia to elicit a neuroinflammatory response. However, the influence α-syn has on DNA methylation and gene expression patterns for other genes has not been thoroughly explored. Our objective is to determine gene expression and methylation changes in microglia induced by aggregate α-syn.METHODS: Transgenic mThy1-Asyn mice overexpressing human α-syn are a model of synucleinopathy. Microglia from 3 and 13-month-old mice were used to isolate nucleic acids for methylated DNA and RNA-sequencing. α-Syn-induced changes in gene expression and genomic methylation were determined and examined for functional enrichment followed by network analysis to further elucidate possible connections within the data.RESULTS: Microglial DNA isolated from our 3-month cohort had 5,315 differentially methylated gene (DMG) changes, while RNA levels demonstrated a change in 119 differentially expressed genes (DEGs) between mThy1-Asyn mice and wild-type littermate controls. The 3-month DEGs and DMGs were highly associated with adhesion and migration signaling, suggesting a phenotypic transition from resting to active microglia. We observed 3,742 DMGs and 3,766 DEGs in 13-month mThy1-Asyn mice.These genes were often related to adhesion, migration, cell cycle, cellular metabolism, and immune response. Network analysis also showed increased cell mobility and inflammatory functions at 3 months, shifting to cell cycle, immune response, and metabolism changes at 13 months.CONCLUSION: We observed significant α-syn-induced methylation and gene expression changes in microglia. Our data suggest that α-syn overexpression initiates microglial activation leading to neuroinflammation and cellular metabolic stresses, which is associated with disease progression.
2021-07-02 | GSE158981 | GEO
Project description:BACKGROUND: Synucleinopathy disorders are characterized by aggregates of α-synuclein (α-syn), which engage microglia to elicit a neuroinflammatory response. However, the influence α-syn has on DNA methylation and gene expression patterns for other genes has not been thoroughly explored. Our objective is to determine gene expression and methylation changes in microglia induced by aggregate α-syn.METHODS: Transgenic mThy1-Asyn mice overexpressing human α-syn are a model of synucleinopathy. Microglia from 3 and 13-month-old mice were used to isolate nucleic acids for methylated DNA and RNA-sequencing. α-Syn-induced changes in gene expression and genomic methylation were determined and examined for functional enrichment followed by network analysis to further elucidate possible connections within the data.RESULTS: Microglial DNA isolated from our 3-month cohort had 5,315 differentially methylated gene (DMG) changes, while RNA levels demonstrated a change in 119 differentially expressed genes (DEGs) between mThy1-Asyn mice and wild-type littermate controls. The 3-month DEGs and DMGs were highly associated with adhesion and migration signaling, suggesting a phenotypic transition from resting to active microglia. We observed 3,742 DMGs and 3,766 DEGs in 13-month mThy1-Asyn mice.These genes were often related to adhesion, migration, cell cycle, cellular metabolism, and immune response. Network analysis also showed increased cell mobility and inflammatory functions at 3 months, shifting to cell cycle, immune response, and metabolism changes at 13 months.CONCLUSION: We observed significant α-syn-induced methylation and gene expression changes in microglia. Our data suggest that α-syn overexpression initiates microglial activation leading to neuroinflammation and cellular metabolic stresses, which is associated with disease progression.
2021-07-02 | GSE158980 | GEO
Project description:C57BL6 mice were subjected to a controlled cortical impact (CCI) to induce a unilateral traumatic brain injury (TBI). After surgery, mice were treated for 5 days with the CSF1R antagonist, PLX3397 or vehicle by daily i.p. injections. PLX3397 is an inhibitor of Colony Stimulating Factor receptor 1 (CSF1R) that leads to a depletion of microglial cells which was confirmed by immunohistochemistry in a subgroup of mice at day 5. Termination of PLX3397 allows for a repopulation of microglial cells which was near complete at 30 days, as assessed by immunofluorescence studies. Perilesional cortical tissue was obtained at the late time point of 30 days after TBI to assess lasting effects of microglia depletion for cortical reorganization that manifested at the transcriptional level. The RNAseq study was done in male and female mice (PLX3397 n = 5 male, 5 female; vehicle n = 5 male, 5 female). Behavioral scores for well-being and motor functions were obatined repeatedly during the observation time. Histology of brain lesion size, indices of neuronal damage and neuroinflammation were obtained at 5d and 30d after TBI. Microglia depletion (PLX3397 treatment) did not reduce the lesion volume and hindered phagocytosis and removal of the hematoma at 5 days, but reduced structural brain damage and neuron loss at 30 days after the injury. Neuroinflammatory markers tended to be lower in PLX3397 treated male than female mice which was associated with better neurological outcome. Overall, CSF1R inhibition provided only subtle lasting beneficial effects.
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Project description:The synaptic protein α-synuclein is linked through genetics and neuropathology to the pathogenesis of Parkinson’s disease and related disorders. However, the mechanisms by which α-synuclein influences disease onset and progression are incompletely understood. To identify novel pathways and potential therapeutic targets we performed proteomic analysis in a highly penetrant new Drosophila model of α-synucleinopathy. We identified 476 significantly upregulated and 563 significantly downregulated proteins in heads from α-synucleinopathy model flies compared to controls. We then used multiple complementary analyses to identify and prioritize genes and pathways within the large set of differentially expressed proteins for functional studies. We performed Gene Ontology enrichment analysis, integrated our proteomic changes with human Parkinson’s disease genetic studies, and compared the α-synucleinopathy proteome with that of tauopathy model flies, which are relevant to Alzheimer’s disease and related disorders. These approaches identified GTP cyclohydrolase (GCH1) and folate metabolism as candidate mediators of α-synuclein neurotoxicity. In functional validation studies we found that knockdown of Drosophila Gch1 enhanced locomotor deficits in α-synuclein transgenic flies, while folate supplementation protected from α-synuclein toxicity. Our integrative analysis suggested that mitochondrial dysfunction was a common downstream mediator of neurodegeneration. Accordingly, Gch1 knockdown enhanced metabolic dysfunction in α-synuclein transgenic fly brains while folate supplementation partially normalized whole brain bioenergetics. Here we outline and implement an integrative approach to identify and validate potential therapeutic pathways using comparative proteomics and genetics and capitalizing on the facile genetic and pharmacological tools available in Drosophila.
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Project description:Aging is the predominant risk factor for neurodegenerative diseases. One key phenotype as brain ages is the aberrant innate immune response characterized by proinflammation. However, the molecular mechanisms underlying aging-associated proinflammation are poorly defined. Whether chronic inflammation plays a causal role in cognitive decline in aging and neurodegeneration has not been established. Here we established a mechanistic link between chronic inflammation and aging microglia, and demonstrated a causal role of aging microglia in neurodegenerative cognitive deficits. Expression of microglial SIRT1 reduces with the aging of microglia. Genetic reduction of microglial SIRT1 elevates IL-1β selectively, and exacerbates cognitive deficits in aging and in transgenic mouse models of frontotemporal dementia (FTD). Interestingly, the selective activation of IL-1β transcription by SIRT1 deficiency is likely mediated through hypomethylating the proximal promoter of IL-1β. Consistent with our findings in mice, selective hypomethylation of IL-1β at two CpG sites are found in normal aging humans and demented patients with tauopathy. Our findings reveal a novel epigenetic mechanism in aging microglia that contributes to cognitive deficits in neurodegenerative diseases.
2014-10-01 | GSE56452 | GEO
Project description:Over the past decade, genetic evidence has demonstrated that microglial dysregulation is likely to play a central role in the development of Alzheimer's disease (AD). As resident immune cells in the brain, microglia become dystrophic and senescent during the chronic progression of AD. To explore whether replenishing the brain with new microglia is beneficial to AD, we employed a CSF1R inhibitor PLX3397 to deplete microglia and induce repopulation after the inhibitor withdrawal in 5xFAD transgenic mice. We observed that microglial repopulation ameliorates AD-associated cognitive deficits, accompanied by elevation of synaptic proteins and hippocampal long-term potentiation (LTP). In addition, microglial morphology is restored after microglial self-renewal, and amyloid pathology is reduced with long-term repopulation but not short-term. Transcriptome analysis showed that repopulating microglia in 5xFAD mice recovers a gene expression profile that is highly similar to microglia from WT mice. Notably, the neurotrophic signaling pathway and hippocampal neurogenesis dysregulated in the AD brain are restored after microglial replenishment. At last, we confirmed that microglial repopulation rescues brain-derived neurotrophic factor (BDNF) expression to contribute to synaptic plasticity. Together, we conclude that microglial self-renewal benefits AD brain by restoring the BDNF neurotrophic signaling pathway. Thus, the proper replenishment of microglia may be an effective and novel therapeutic strategy for ameliorating cognition impairment in AD.
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