Genome-wide analysis of LPS-responsive gene expression by microglia cells in Ntg and LRRK2KO mouse brain
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ABSTRACT:
ORGANISM(S): Mus musculus
SUBMITTER: Lixin Sun
PROVIDER: E-GEOD-83562 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Analysis of LRRK2-regulation of microglia responce to the LPS at gene expression level. The hypothesis tested in the present study was whether LRRK2 influence the microglial phagocytosis- and neuroinflammation- related gene expression at mRNA level.
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Project description:BACKGROUND: Previous data implicates neuroinflammation in the pathogenesis of Parkinson’s disease (PD). Of the genes associated with PD, Leucine rich repeat kinase 2 (LRRK2) is expressed in microglia, resident brain inflammatory cells. However, the extent to which LRRK2 affects neuroinflammatory responses is unclear. OBJECTIVE: To examine whether mutations in Lrrk2 affect responses to neuroinflammation in vivo. METHODS: We injected cohorts of mice carrying mutations in Lrrk2, homologous to those causing human PD, with a single intrastriatal injection of lipopolysaccharide (LPS) or control. We used single cell RNA-Sequencing to examine cell type specific responses to treatment and genotype and validated key results with orthogonal approaches. RESULTS: We found that our chosen paradigm of acute LPS exposure evokes robust transcriptional changes consistent with a multicellular neuroinflammatory response. We also found evidence of peripheral immune cell recruitment into the brain and interaction with brain-resident microglia. However, the transcriptional effects of Lrrk2 mutations were limited to small numbers of genes, including down regulation of gene ontogeny terms related to lysosomes, predominantly in microglia. CONCLUSIONS: Our data clearly demonstrate that many cells in the brain respond to a single inflammatory insult with strong transcriptional responses and that, even in a model focussed on CNS injection, there is interaction between peripheral and central immune cells. In contrast, the quantitative effects of Lrrk2 mutations are modest at least at the level of transcription, demonstrating that additional studies are needed to clarify whether Lrrk2 affects neuroinflammation in an endogenous context.
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Project description:We used the RNA-Sequencing to obtain transcriptomic profiles of LRRK2 wild-type (WT) and knock-out (KO) microglia cells treated with α-synuclein pre-formed fibrils (PFFs) or lipopolysaccharide (LPS) as a general inflammatory insult. Conclusion: overall, the results suggest that microglial LRRK2 may contribute to the pathogenesis of PD via altered oxidative stress signaling.
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Project description:Mutations in leucine-rich repeat kinase 2 (LRRK2) cause autosomal dominant Parkinson’s disease (PD) while polymorphic LRRK2 variants are associated with sporadic PD. PD-linked mutations increase LRRK2 kinase activity and induce neurotoxicity in vitro and in vivo. The small GTPase Rab8a is a LRRK2 kinase substrate and is involved in receptor-mediated recycling and endocytic trafficking of transferrin, but the effect of PD-linked LRRK2 mutations on the function of Rab8a is poorly understood. Here, we show that gain-of-function mutations in LRRK2 induce sequestration of endogenous Rab8a to lysosomes in over-expression cell models while pharmacological inhibition of LRRK2 kinase activity reverses this phenotype. Furthermore, we show that LRRK2 mutations drive association of endocytosed transferrin with Rab8a-positive lysosomes. LRRK2 has been nominated as an integral part of cellular responses downstream of proinflammatory signals and is activated in microglia in post-mortem PD tissue. Here, we show that iPSC-derived microglia from patients carrying the most common LRRK2 mutation, G2019S, mistraffic transferrin to lysosomes proximal to the nucleus in proinflammatory conditions. Furthermore, G2019S knock-in mice show a significant increase in iron deposition in microglia following intrastriatal LPS injection compared to wild type mice, accompanied by striatal accumulation of ferritin. Conclusion: Our data support a role of LRRK2 in modulating iron uptake and storage in response to proinflammatory stimuli in microglia. Neuroinflammation remodels endolysosomal gene expression in microglia, in vitro and in vivo.
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Project description:Sepsis associated encephalopathy (SAE), a common complication of sepsis, seriously affect the prognosis and quality of life to sepsis patients. Microglia activation is vital to the neuroinflammation and the pathology of SAE. Mild hypothermia, that a useful procedure in the treatment of traumatic brain injuries, was found to suppress microglia activation. In present study, in vitro cultured BV-2 microglial cells stimulated with LPS was employed as the model of microglia activation. The altered signitures of lncRNAs, circRNAs and mRNAs of LPS exposure and mild hypothermia were arrayed by using the Agilent ceRNA Microarray Chip.
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Project description:Rehabilitative training is an effective method to promote recovery following spinal cord injury (SCI), with lower training efficacy observed in the chronic stage. The increased training efficacy during the subacute period is associated with an adaptive state induced by the SCI. A potential link is SCI-induced inflammation, which is elevated in the subacute period, and as injection of lipopolysaccharide (LPS) alongside training improves recovery in chronic SCI, suggesting LPS could reopen a window of plasticity late after injury. Microglia may play a role in LPS-mediated plasticity as they react to LPS and are implicated in facilitating recovery following SCI. However, it is unknown how microglia change in response to LPS following SCI to promote neuroplasticity. Here we used single-cell RNA sequencing to examine microglial responses in subacute and chronic SCI with and without an LPS injection. We show that subacute SCI is characterized by a disease-associated microglial (DAM) signature, while chronic SCI is highly heterogeneous, with both injury-induced and homeostatic states. With LPS injection, microglia shifted away from the homeostatic signature to a primed, translation-associated state and increased DAM in degenerated tracts caudal to the injury. Our results contribute to an understanding of how microglia and LPS-induced neuroinflammation contribute to plasticity following SCI.
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