Project description:Microglia are the resident macrophages of the central nervous system (CNS). Gene profiling identified the transcriptional regulator Sall1 as a microglia signature gene. Given the high expression of Sall1 in microglia, we sought to identify its function in vivo. The Sall1CreER allele has been targeted into the Sall1 locus, therefore Sall1CreER/fl mice (heterozygous for both alleles) allow inducible ablation of Sall1 expression in microglia after tamoxifen treatment. We performed RNA-seq to examine gene expression profiles of microglia sorted from tamoxifen treated adult Sall1CreER/fl mice and Sall1fl/fl control littermates. Microglia were obtained with > 98% purity and the absence of Sall1 was confirmed in Sall1CreER/fl microglia. We could show that deletion of Sall1 in microglia in vivo resulted in the conversion of these cells from resting tissue macrophages into inflammatory phagocytes leading to altered neurogenesis and disturbed tissue homeostasis. Similar changes in gene expression profiles were found in Sall1-deficient microglia isolated from tamoxifen-treated Cx3cr1CreERSall1fl/fl mice. In these mice, deletion of Sall1 is targeted to CX3CR1+ myeloid cells including microglia and CNS-associated macrophages but not to any other CNS-resident cells. This indicated that Sall1 transcriptional regulation maintains microglia identity and physiological properties in the CNS.
Project description:CX3CR1, one of the highest expressed genes in microglia in mice and humans, is implicated in numerous microglial functions. However, the molecular mechanisms underlying Cx3cr1 signaling are not well understood. Here, we analyzed transcriptomes of Cx3cr1-deficient microglia under varying conditions by RNA-Seq. In 2 mos mice, Cx3cr1 deletion resulted in the downregulation of a subset of immune-related genes, without substantial epigenetic changes in markers of active chromatin. Surprisingly, Cx3cr1-deficient microglia from young mice exhibited a transcriptome consistent with that of aged Cx3cr1-sufficient animals, suggesting a premature aging transcriptomic signature. Immunohistochemical analysis of microglia in young and aged mice revealed that loss of Cx3cr1 modulates microglial morphology in a compatible fashion. Our results suggest that CX3CR1 may regulate microglial function in part by modulating the expression levels of a subset of inflammatory genes during chronological aging, making Cx3cr1-deficient mice useful for studying aged microglia.
Project description:CX3CR1, one of the highest expressed genes in microglia in mice and humans, is implicated in numerous microglial functions. However, the molecular mechanisms underlying Cx3cr1 signaling are not well understood. Here, we analyzed transcriptomes of Cx3cr1-deficient microglia under varying conditions by RNA sequencing (RNA-Seq). In 2 mos mice, Cx3cr1 deletion resulted in the downregulation of a subset of immune-related genes, without substantial epigenetic changes in markers of active chromatin. Surprisingly, Cx3cr1-deficient microglia from young mice exhibited a transcriptome consistent with that of aged Cx3cr1-sufficient animals, suggesting a premature aging transcriptomic signature.
Project description:After irradiation and bone-marrow transplantation, most of microglia and boarder-associated macrophages in the central nervous system is replaced by engranft cells. Taking advantages of Ms4a3-Cre: R26-TdTomato: Cx3cr1-gfp mice, we discriminated cells from monocyte precursors and hematopoietic stem cells with colors at 32 weeks following irradiation and bone-marrow transplantation. We sorted HSC-derived, monocyte-derived, and endogenouse microglia and leptomeningeal macrophages, and analyzed gene expression level between different cell populations using a bulk RNAseq method.
Project description:Cx3cr1CreER driven Cre-recombinase (Cre) is a widely used genetic tool for enabling gene manipulation in microglia and macrophages. However, an in-depth analysis for the possible detrimental effects of Cre-activity in microglia, surprisingly remains missing. Here we demonstrate an age-dependent sensitivity of microglia to Cx3cr1-Cre-toxicity, wherein Cre-induction specifically in early postnatal microglia is detrimental for microglial development, proliferation and function. Tamoxifen (TAM) induced Cre-activity leads to microglial activation, type1-interferon (IFN-1) signaling and increased phagocytosis, causing aberrant synaptic pruning during early postnatal period and anxiety behavior in later age. The detrimental effects of Cre-induction are caused due to DNA-damage induced toxicity in microglia, and is limited to the early postnatal period, showing no detrimental effects in adult microglia. Thus, our study reveals the age-dependent vulnerability of microglia to Cre-activity, thereby highlighting age-dependencies of Cre-action, which could be especially applicable in the broader context of environment-responsive cell-types.
Project description:single cell gene expression profiling of microglia after peripheral nerve injury in Cx3cr1-yfp-creER/+ animals and Cx3cr1-yfp-creER/+; Tnfaip3 fl/fl animals
Project description:We previously discovered a sex-by-genotype defect in microglia function using a germline heterozygous knockout mouse model of Neurofibromatosis type 1 (Nf1+/- mice), in which only microglia from male Nf1+/- mice exhibited defects in purinergic signaling. Herein, we leveraged an unbiased proteomic approach to demonstrate that male, but not female, heterozygous Nf1+/- microglia exhibit differences in protein expression, which largely reflect pathways involved cytoskeletal organization. In keeping with potential defects in cytoskeletal function, only male Nf1+/- microglia had reduced process arborization and surveillance capacity. Next, to determine whether these microglial defects were cell autonomous or reflected adaptive responses to Nf1 heterozygosity in other cells in the brain, we generated conditional microglia Nf1-mutant knockout mice by intercrossing Nf1flox/flox with Cx3cr1-CreER mice (Nf1flox/wt; Cx3cr1-CreER mice, Nf1MG+/- mice). Surprisingly, neither male nor female Nf1MG+/- mouse microglia had impaired process arborization or surveillance capacity. In contrast, when Nf1 heterozygosity was generated in neurons, astrocytes and oligodendrocytes by intercrossing Nf1flox/flox with hGFAP-Cre mice (Nf1flox/wt; hGFAP-Cre mice, Nf1GFAP+/- mice), the microglia defects found in Nf1+/- mice were recapitulated. Collectively, these data reveal that Nf1+/- sexually dimorphic microglia abnormalities are likely not cell-intrinsic properties, but rather reflect a response to Nf1 heterozygosity in other brain cells.
Project description:Purpose: Purpose:To gain a deeper insight into how microglia homeostasis regulates regulates neurogenesis through epigenetic ARID1A, RNA-sequencing (RNA-seq) was performed to analyze the genome-wide changes by ARID1A deletion in microglia at E14. Methods: The microglia was extracted from E14 of Arid1acKO and Arid1afl/fl mice by fluorescence activated cell sorting. Total RNA was immediately extracted by using the RNAeasy Mini kit (QIAGEN) following the manufacturer’s instructions. Then total RNA was quality controlled and quantified using an Agilent 2100 Bioanalyzer. After converting to cDNA and building library, high-throughput sequencing was performed using the Illumina HiSeq 2500 platform in Annoroad Genomics. Results: Approximately approximately two thousands transcripts showed differential expression between the Arid1afl/fl and Arid1acKO brain cortex, with a fold change ≥2.0 and p value <0.05. Gene ontology (GO) analysis showed that the down-regulated genes were enriched in the terms related to neurogenesis, regulation of cell communication and chemokine-mediated signaling pathway. Up-regulated genes showed a significant enrichment of terms involved in negative regulation of forebrain neuron fate commitment and cell surface receptor signaling pathway involved in cell-cell signaling. These results reflected the importance of ARID1A regulates neurogenesis through remodeling microglia states. Conclusions: We conclude that RNA-seq based transcriptome characterization would provide a framework for understanding how ARID1A regulates neurogenesis through remodeling microglia states brain cortical development.
Project description:To investigate the roll of ARID1A in the regulation of effector CD8+ T cell responses, we crossed GzmB-Cre P14 Thy1.1 mice with Arid1a-fl/fl mice to generate Arid1a Het and KO mice. We then performed gene expression profiling analysis of WT, Het, and KO cells in vivo at d3, d5, and d8 post-LCMV Armstrong infection.
Project description:We wished to investigate the role of E-cadherin loss in our mouse parietal cell/pre-parietal cell E-cadherin knock-out, p53 knock-out, oncogenic Kras induced model of gastric cancer. As such, we isolated RNA from stomach tissue from our E-cadherin knock-out model (Atp4b-Cre;Cdh1(fl/fl);Kras(LSL-G12D/+);Trp53(fl/fl);Rosa26(LSL-YFP/LSL-YFP)) and our E-cadherin heterozygous model (Atp4b-Cre;Cdh1(fl/+);Kras(LSL-G12D/+);Trp53(fl/fl);Rosa26(LSL-YFP/LSL-YFP)). We then performed a microarray on this stomach tissue from four independent mice of each genotype. Differentially expressed genes were identified and gene set overlap analysis was used to identify pathways enriched in one model over the other.