Defining the microglial transcriptome in the rat subventricular zone (SVZ) after neonatal hypoxia-ischemia (HI).
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ABSTRACT: Purpose: Recent findings indicate a regulatory role of microglia on neurogenesis in the SVZ in health and disease. Microglia in the early postnatal SVZ are not fully maturated and may react differently than adult microglia to injury. We sought to investigate the impact of cortico-striatal neonatal HI injury on the microglial phenotype in the early postnatal SVZ. Results: In comparison to sham SVZ microglia, HI SVZ microglia upregulate both pro- and anti-inflammatory genes as well as neurotrophic genes. HI SVZ microglia do not adopt a M1 or M2 polarization state, but instead share commonly expressed genes with microglia in rodent models of neurodegenerative diseases.
Project description:Transcriptional profiling of mouse postnatal SVZ NSCs comparing WT NSCs with KO NSCs under proliferating/undifferentiated states as well as differentiating conditions. Goal was to determine Dnmt3a-dependent gene expression changes in postnatal SVZ NSCs
Project description:Transcriptional profiling of mouse postnatal SVZ NSCs comparing WT NSCs with KO NSCs under proliferating/undifferentiated states as well as differentiating conditions. Goal was to determine Dnmt3a-dependent gene expression changes in postnatal SVZ NSCs Two-condition experiment with a dye-swap design, WT NSCs vs. KO NSCs. Biological replicates: 4 replicates under proliferating/undifferentiation conditions, 2 replicates under differentiating conditions.
Project description:We performed large-scale single cell profiling of dissociated V-SVZ and OB cells from the same animal carrying either the hGFAP::CreERT2; Rosa26LSL-TdTomato (GCERT2) reporter, or ratNes::FLPOER; Rosa26FSF-TdTomato (NesFLPO) reporter. Scope-Seq profiling was performed on dissociated V-SVZ cells from C57BL/6J animals.
Project description:The mammalian adult brain contains two neural stem and precursor (NPC) niches: subventricular zone [SVZ] lining the lateral ventricles and subgranular zone [SGZ] in the hippocampus. From these SVZ NPCs represent the largest NPC pool. Notably, while SGZ NPCs typically only produce neurons and astrocytes, SVZ NPCs produce neurons, astrocytes and oligodendrocytes throughout life. Of particular importance is the generation and replacement of oligodendrocytes, the only myelinating cells of the central nervous system (CNS). SVZ NPCs contribute to myelination by regenerating oligodendrocyte precursor cell (OPC) pool and by differentiating into oligodendrocytes in the developing and demyelinated brain. The neurosphere assay has been widely adopted by the scientific community to facilitate the study of NPCs in vitro. Here, we present a streamlined protocol for culturing postnatal and adult SVZ NPCs and OPCs from primary neurosphere cells. We characterize the purity and differentiation potential as well as provide RNA-sequencing profiles of postnatal SVZ NPCs, postnatal SVZ OPCs and adult SVZ NPCs. We show that primary neurospheres cells generated from postnatal and adult SVZ differentiate into neurons, astrocytes and oligodendrocytes concurrently and at comparable levels. SVZ OPCs are generated by subjecting primary neurosphere cells to OPC growth factors fibroblast growth factor (FGF) and platelet-derived growth factor-AA (PDGF-AA). We further show SVZ OPCs can differentiate into oligodendrocytes in the absence and presence of thyroid hormone T3. Transcriptomic analysis confirmed the identities of each cell population and revealed novel immune and signalling pathways expressed in an age and cell type specific manner.
Project description:Throughout postnatal life in mammals, neural stem cells (NSCs) are located in the subventricular zone (SVZ) of the lateral ventricles. The greatest diversity of neuronal and glial lineages they generate occurs during early postnatal life in a region-specific manner. In order to evaluate potential heterogeneity in the NSC pool, we microdissected the dorsal and lateral SVZ at different postnatal ages and isolated NSCs and their immediate progeny based on their expression of Hes5-EGFP/Prominin1 and Ascl1-EGFP, respectively. Whole genome comparative transcriptome analysis revealed transcriptional regulators as major hallmarks that sustain postnatal SVZ regionalization. Manipulation of single genes encoding for locally enriched transcription factors influenced NSC specification indicating that the fate of regionalized postnatal SVZ NSCs can be readily modified . These findings reveal functional heterogeneity of NSCs in the postnatal SVZ and provide targets to recruit region-specific lineages in regenerative contexts. Microarrays of neural stem cells, early progenitors and the tissue from subregions of the subventricular zone were compiled to screen for the full extent of heterogeneity in this region during postnatal life.
Project description:Throughout postnatal life in mammals, neural stem cells (NSCs) are located in the subventricular zone (SVZ) of the lateral ventricles. The greatest diversity of neuronal and glial lineages they generate occurs during early postnatal life in a region-specific manner. In order to evaluate potential heterogeneity in the NSC pool, we microdissected the dorsal and lateral SVZ at different postnatal ages and isolated NSCs and their immediate progeny based on their expression of Hes5-EGFP/Prominin1 and Ascl1-EGFP, respectively. Whole genome comparative transcriptome analysis revealed transcriptional regulators as major hallmarks that sustain postnatal SVZ regionalization. Manipulation of single genes encoding for locally enriched transcription factors influenced NSC specification indicating that the fate of regionalized postnatal SVZ NSCs can be readily modified . These findings reveal functional heterogeneity of NSCs in the postnatal SVZ and provide targets to recruit region-specific lineages in regenerative contexts. Microarrays of neural stem cells, early progenitors and the tissue from subregions of the subventricular zone were compiled to screen for the full extent of heterogeneity in this region during postnatal life. Spatially distinct regions of the developing forebrain subventricular zone (SVZ) aged at P4, P8 and P11 were microdissected in RNAse free/sterile conditions. Mice expressing Ascl1-EGFP in the SVZ were used to aid accurate microdissection of the dorsal and lateral wall of each of the studied time points as per our previous publications characterizing this method. As well as at the whole microdomain level, additionally, NSCs (Hes5-EGFP+/Prom1+) and early progenitors (Ascl1-EGFP+) from each microdomain were further isolated by FAC sorting methods. This was to provide a comprehensive gene expression analysis at the tissue level and at the cellular level. Generally, 1 litter was used to yield 1 'n' number of replicates. A total of 23 affymetrix analysis were performed.
Project description:We performed large-scale single cell profiling of V-SVZ cells, following separate dissections of the lateral and septal walls of 8-10 week old male and female mice.
Project description:DNA methylation at proximal promoters facilitates lineage restriction by silencing cell-type specific genes. However, euchromatic DNA methylation frequently occurs in regions outside promoters. The functions of such non-proximal promoter DNA methylation are unclear. Here we show that the de novo DNA methyltransferase Dnmt3a is expressed in postnatal neural stem cells (NSCs) and is required for neurogenesis. Genome-wide analysis of postnatal NSCs indicates that Dnmt3a occupies and methylates intergenic regions and gene bodies flanking proximal promoters of a large cohort of transcriptionally permissive genes, many of which encode regulators of neurogenesis. Surprisingly, Dnmt3a-dependent non-proximal promoter methylation promotes expression of these neurogenic genes by functionally antagonizing Polycomb repression. Thus, non-promoter DNA methylation by Dnmt3a may be utilized for maintaining active chromatin states of genes critical for development. Chromatin extracted from wild-type (WT) or Dnmt3a-null (KO) SVZ NSCs was immunoprecipitated with indicated antibodies and analyzed by NimbleGen 2.1M mouse whole genome tiling microarrays (a 4-array set covering the entired non-repetitive portion of mouse genome). Whole cell extract (WCE) was used as input controls for IP/WCe experiments. For IP/IP experiments, immunoprecipitated DNA from WT and KO NSCs was directly compared on the same microarrays. For identifying Dnmt3a-dependent DNA methylation at a genome-wide scale, a dye-swap design was employed for comparing DNA methylation levels between WT and KO SVZ NSCs.
Project description:Microglia are the primary phagocytes in the central nervous system and are responsible for clearing dead cells generated during development or disease. The phagocytic process shapes the phenotype of the microglia, which affects the local environment. A unique population of microglia reside in the ventricular-subventricular zone (V-SVZ) of neonatal mice, but how they influence this neurogenic niche is not well-understood. Here, we demonstrate that phagocytosis creates a pro-neurogenic microglial phenotype in the V-SVZ and that these microglia phagocytose apoptotic cells via the engulfment receptor Jedi-1. Deletion of Jedi-1 decreases apoptotic cell clearance, triggering the development of a neuroinflammatory phenotype, reminiscent of neurodegenerative and-age-associated microglia, that reduces neural precursor proliferation via elevated interleukin (IL)-1β signaling; inhibiton of IL-1 receptor rescues precursor proliferation in vivo. Together, these results reveal a critical role for Jedi-1 in connecting microglial phagocytic activity to a phenotype that promotes neurogenesis in the developing V-SVZ. We performed RNAseq on MACS-sorted microglia from V-SVZ and Cortex of WT and Jedi-1 knockout P7 mice.
Project description:After a stroke, the neurogenic response from the subventricular zone (SVZ) to repair the brain is limited. Microglia, as an integral part of the distinctive SVZ microenvironment, control neural stem / precursor cell (NSPC) behavior. Here, we show that discrete stroke-associated SVZ microglial clusters negatively impact the innate neurogenic response, and we propose a repository of relevant microglia–NSPC ligand–receptor pairs. After photothrombosis, a mouse model of ischemic stroke, the altered SVZ niche environment leads to immediate activation of microglia in the niche and an abnormal neurogenic response, with cell-cycle arrest of neural stem cells and neuroblast cell death. Pharmacological restoration of the niche environment increases the SVZ-derived neurogenic repair and microglial depletion increases the formation and survival of newborn neuroblasts in the SVZ. Therefore, we propose that altered cross-communication between microglial subclusters and NSPCs regulates the extent of the innate neurogenic repair response in the SVZ after stroke.