Prrc2a-mediated post-transcriptional modulation shapes microglial function and cerebellar development
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE257550 | GEO | 2025/01/16
REPOSITORIES: GEO
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Project description:Specific medications to combat cerebellar ataxias, a group of debilitating movement disorders characterized by difficulty with walking, balance and coordination. Notably, cerebellar microglial activation appears to be a common feature in different types of ataxic patients and rodent models. However, the causal link between the activation of microglia in the cerebellum and ataxias remains inconclusive. In the present study, using a classic mouse model of cerebellar ataxia induced by 3-acetylpyridine (3-AP), we find a early-onset and long-lasting microglial activation accompanied by neuronal loss and dysfunction in the cerebellum. Transcriptome and behavior analyses indicate that microglial depletion in 3-AP ataxic mice decreases neuroinflammatory response in the cerebellum and rescues the ataxic motor symptoms including motor incoordination, gait abnormality, and locomotor dysfunction. Moreover, specific chemogenetic activation of cerebellar microglia in the vermis by M3D(Gq), a designer receptor exclusively activated by designer drugs (DREADDs), directly induces an expression of pro-inflammatory cytokines and aggravates ataxic motor deficits of 3-AP mice. On the contrary, inhibition of cerebellar microglial activation by M4D(Gi) or minocycline reduces the production of pro-inflammatory cytokines including TNF-α and alleviates motor deficits. Furthermore, blockage of TNF-α signaling attenuates the microglial-triggered hyperactivity of Purkinje cells (PCs). These results suggest that cerebellar microglial activation aggravates neuroinflammatory response, and subsequently induces dysfunction of PCs, which in turn triggers ataxic motor deficits. Our findings thus reveal a causal relationship between pro-inflammatory activation of cerebellar microglia and the ataxic motor symptoms, which may offer novel evidence for therapeutic intervention for cerebellar ataxias by targeting microglia and microglia-derived inflammatory mediators.
2023-07-01 | GSE221991 | GEO
Project description:Niemann-Pick type C (NPC) disease is an inherited lysosomal storage disorder mainly driven by mutations in NPC1 gene, causing lipid accumulation within late endosomes/lysosomes, and resulting in progressive neurodegeneration. Although microglial activation proceeds neuronal loss, it remains elusive whether loss of NPC1 in microglia actively contributes to NPC pathology. Here, we used a mouse model with depletion of NPC1 in myeloid cells to investigate the role of microglia in Niemann-Pick disease. In order to achieve the loss of NPC1 in myeloid cells, mice with floxed Npc1 alleles (Npc1 flox/flox) were crossed with mice expressing the constitutively active Cre recombinase under the myeloid-specific promotor of Cx3cr1. Hyperactive microglia initiated a pathological cascade resembling NPC-like phenotypes, including shortened lifespan, motor impairments, astrogliosis, neuroaxonal pathology and increased levels of neuronal injury biomarker NF-L. To study the differential vulnerability between the brain regions, we compared the cerebellar with the cerebral (brain without cerebellum) proteome in Cre- and Cre+ mice at late pathological stages. Our results suggest that microglial loss of NPC1 has profound effects on brain cell homeostasis especially in the cerebrum.
2024-12-05 | PXD056188 | Pride
Project description:Microglia colonize the brain parenchyma at early stages of development and accumulate in specific regions where they actively participate in cell death, angiogenesis, neurogenesis and synapse elimination. A recurring feature of embryonic microglial distribution is their association with developing axon tracts which, together with in vitro data, supports the idea of a physiological role for microglia in neurite development. Yet the demonstration of this role of microglia is still lacking. Here, we have studied the consequences of microglial dysfunction on the formation of the corpus callosum, the largest connective structure in the mammalian brain, which shows consistent microglial accumulation during development. We studied two models of microglial dysfunction: the loss-of-function of DAP12, a key microglial-specific signaling molecule, and a model of maternal inflammation by peritoneal injection of LPS at E15.5. We performed transcriptional profiling of maternally inflamed and Dap12-mutant microglia at E17.5. We found that both treatments principally down-regulated genes involved in nervous system development and function, particularly in neurite formation. We then analyzed the functional consequences of these microglial dysfunctions on the formation of the corpus callosum. We also took advantage of the Pu.1-/- mouse line, which is devoid of microglia. We now show that all three models of altered microglial activity resulted in the same defasciculation phenotype. Our study demonstrates that microglia are actively involved in the fasciculation of corpus callosum axons. To investigate possible roles for microglial during brain development, we challenged microglial function by two complementary approaches. First, we induced maternal inflammation by peritoneal injection of LPS into pregnant dams. Next, we analyzed the consequences of a loss of function of DAP12, a signaling molecule specifically expressed in microglia that is crucial for several aspects of microglia biology (references in Wakselman et al., 2008). We compared the gene expression profiles of microglia from control, maternally-inflamed by LPS (MI), and Dap12-mutated embryos. We isolated RNA from FACS sorted maternally inflamed (by LPS) and Dap12-mutant microglia at E17.5 pooled per pregnant dam; as a control we included PBS treated and untreated (UT) microglia. We compared gene expression between maternally inflamed microlgia (PBSvsLPS) and DAP12-mutant microglia (UTvsDAP12KO).
2014-07-01 | E-GEOD-49079 | biostudies-arrayexpress
Project description:Microglia, resident immune cells in the central nervous system, undergo morphological and functional changes in response to signals from the local environment and mature into various homeostatic states. However, niche signals underlying microglial differentiation and maturation remain unknown. Here, we show that neuronal micronuclei transfer to microglia, which is followed by changing microglial characteristics during the postnatal period. Neurons passing through a dense region of the developing neocortex give rise to micronuclei and release them into the extracellular space, before being incorporated into microglia and inducing morphological changes. Two-photon imaging analyses have revealed that microglia incorporating micronuclei tend to slowly retract their processes. Loss of the cGAS gene alleviates effects on micronucleus-dependent morphological changes. Neuronal micronuclei-harboring microglia also exhibit unique transcriptome signatures. These results demonstrate that neuronal micronuclei serve as niche signals that transform microglia, and provide a potential mechanism for regulation of microglial characteristics in the early-postnatal neocortex.
2024-12-29 | PXD056089 | Pride
Project description:Preparation of primary microglial cultures from postnatal mice is tedious with a low yield, high variability and risk of astrocytic contamination. Microglia derived from embryonic stem cells (ESdM) have been suggested as alternative source, but it is unclear how closely ESdM resemble the molecular phenotype of primary microglia. Here, we performed a whole transcriptome analysis of ESdM in comparison to primary cultured and flow cytometry-sorted microglia and compared the microglial transcriptome to other cell types. Cultured microglia and ESdM were related to sorted microglia, but clearly distinct from other myeloid cell types, T cells, astrocytes and neurons. ESdM and primary cultured microglia showed strong overlap in their transcriptome. Only 144 gene transcripts were differentially expressed between both cell types, mainly derived from immune-related genes with a higher activation status of pro-inflammatory and immune defense genes in primary microglia compared to ESdM. Flow cytometry analysis of cell surface markers CD54, CD74 and CD274 selected from the microarray confirmed the close phenotypic relation between ESdM and primary cultured microglia. Thus, assessment of genome-wide transcriptional regulation demonstrates that microglia are distinct from other macrophage cell types and that mouse pluripotent stem cell-derived microglia are closely related to cultured postnatal microglia. Comparison of different primary neuronal cells with ES-cell derived microglial cells
2013-07-11 | E-GEOD-43808 | biostudies-arrayexpress
Project description:Microglia are tissue macrophages of the central nervous system (CNS) that control tissue homeostasis, and as such they are crucially important for organ integrity. Microglia dysregulation is thought to be causal for a group of neuropsychiatric, neurodegenerative and neuroinflammatory diseases, called ‘microgliopathies’. However, how the intracellular stimulation machinery in microglia is controlled is poorly understood. By using expression studies, we identified the ubiquitin-specific protease (Usp) 18 in white matter microglia that essentially contributes to microglial quiescence under homeostatic conditions. We further found that microglial Usp18 negatively regulated the activation of STAT1 and concomitant induction of interferon-induced genes thereby disabling the termination of IFN signalling. Unexpectedly, the Usp18-mediated feedback loop was independent from the catalytic domain of the protease but instead required the interacting region of Ifnar2. Additionally, the absence of Ifnar1 completely rescued microglial activation indicating a tonic IFN signal mediated by receptor interactions under non-diseased conditions. Finally, conditional depletion of Usp18 only in myeloid cells significantly enhanced the disease burden in a mouse model of CNS autoimmunity, increased axonal and myelin damage and determined the spatial distributions of CNS lesions that shared the same STAT1 signature as myeloid cells found in active multiple sclerosis (MS) lesions. These results identify Usp18 as novel negative regulator of microglia activation, demonstrate a protective role of the IFNAR pathway for microglia and establish Usp18 as potential therapeutic target for the treatment of MS. Brain lysate of adult WT, USP18ko, IFNAR1ko and USP18ko:IFNARko mice were analyzed
2015-04-20 | E-GEOD-61499 | biostudies-arrayexpress
Project description:Microglia are tissue macrophages of the central nervous system (CNS) that control tissue homeostasis, and as such they are crucially important for organ integrity. Microglia dysregulation is thought to be causal for a group of neuropsychiatric, neurodegenerative and neuroinflammatory diseases, called ‘microgliopathies’. However, how the intracellular stimulation machinery in microglia is controlled is poorly understood. By using expression studies, we identified the ubiquitin-specific protease (Usp) 18 in white matter microglia that essentially contributes to microglial quiescence under homeostatic conditions. We further found that microglial Usp18 negatively regulated the activation of STAT1 and concomitant induction of interferon-induced genes thereby disabling the termination of IFN signalling. Unexpectedly, the Usp18-mediated feedback loop was independent from the catalytic domain of the protease but instead required the interacting region of Ifnar2. Additionally, the absence of Ifnar1 completely rescued microglial activation indicating a tonic IFN signal mediated by receptor interactions under non-diseased conditions. Finally, conditional depletion of Usp18 only in myeloid cells significantly enhanced the disease burden in a mouse model of CNS autoimmunity, increased axonal and myelin damage and determined the spatial distributions of CNS lesions that shared the same STAT1 signature as myeloid cells found in active multiple sclerosis (MS) lesions. These results identify Usp18 as novel negative regulator of microglia activation, demonstrate a protective role of the IFNAR pathway for microglia and establish Usp18 as potential therapeutic target for the treatment of MS. Primary microglia (WT, USP18ko and USP18_C61A mice) and BV-2 cells (treated with control siRNA or siRNA against USP18) were incubated with 500 U/ml IFN-b. At different timepoints (0h, 6h, and 24h) RNA samples were taken and analyzed via Microarray
2015-04-20 | E-GEOD-61500 | biostudies-arrayexpress
Project description:Background Friedreich’s ataxia (FRDA) is a rare genetic disorder characterized by motor discoordination and predominant cerebellar involvement. It is caused by mutations leading to decreased transcription of frataxin (FXN), a gene encoding for a mitochondrial protein involved in the biogenesis of iron-sulfur clusters and iron handling. Many advances have been achieved in understanding the pathophysiology of FRDA and the mechanisms whereby FXN deficiency causes cerebellar degeneration. However, the issue concerning the contribution of central nervous system-resident non-neuronal cells to the pathogenesis of FRDA is still poorly explored. In this work, we set out to verify if specific vulnerabilities of cerebellar microglia could be involved in the pathogenesis of FRDA. Methods Primary cerebellar microglia were obtained from the KIKO mouse model of FRDA. We analyzed their phenotype and functions by a multilayer study, encompassing morphological analysis, migration and phagocytosis assays, gene expression by RNA-seq, RT-PCR, western blot, and immunofluorescence. Mitochondria functionality was evaluated by flow cytometry and real-time metabolic analysis. We assessed the effect of FRDA microglia on cell viability and neurite length in primary neurons. We analyzed in vivo microglia phenotype in the cerebellum of KIKO miceduring an early developmental stage by means of morphology analysis, RT-PCR and immunofluorescence. Results We demonstrated that FRDA microglia exhibit traceable morphological, transcriptional and functional changes, particularly regarding inflammatory pathways and mitochondria functionality. In addition, we found that FRDA microglia impair neuron survival and neurite length in vitro. Finally, we showed that cerebellar microglia in vivo exhibit dysregulations at early postnatal age of FRDA mice. Conclusions These results indicate that FRDA microglia display aberrant features and may participate in neuron dysfunction, evidencing a non-cell-autonomous mechanism in FRDA. Therefore, microglia targeting could be a valuable strategy in ameliorating cerebellar degeneration in the disease.
2024-08-26 | GSE232826 | 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:Neurons within the cerebellum form temporal-spatial connections through the cerebellum, and the entire brain. Organoid models provide an opportunity to model the early differentiation of the developing human cerebellum, which is difficult to study in vivo, and affords the opportunity to study neurodegenerative and neurodevelopmental diseases of the cerebellum. Previous cerebellar organoid models focused on early neuron generation and single cell activity. Here, we modify previous protocols to generate more mature cerebellar organoids that allow for the establishment of several classes of mature neurons during cerebellar differentiation and development, including the establishment of neural networks during whole organoid maturation. This will provide a means to study the generation of several more mature cerebellar cell types, including Purkinje cells, granule cells, interneurons expression as well as neuronal communication for biomedical, clinical, and pharmaceutical application.
2023-07-20 | GSE237855 | GEO