Project description:To probe potential molecular mechanisms underlying the differences between wild-type and Hk2-cKO microglia during repopulation, we performed the single-cell RNA sequencing (scRNA-seq) of repopulated microglia at Day 3. Microglia were isolated by FACS as CD11b high CD45 low cells from normal brains and Hk2-cKO brains.
Project description:We developed an experimental model system in mice, in which microglia can be depleted selectively and temporarily from the prefrontal cortex (PFC) during a defined window of adolescence (6 weeks of age). This was achieved using a single, bilateral stereotaxic intra-PFC injection of clodronate disodium salt (CDS), which induces selective apoptosis of microglia. To ascertain the cellular selectivity of intra-PFC administration of CDS, we conducted next-generation RNA sequencing (RNAseq) of bulk medial PFC tissue from CDS- or phosphate buffered saline (PBS)-injected mice. PFC samples were extracted either during the peak of microglia depletion, that is, 5 days post injection (5 dpi) or in adulthood (12 weeks of age) after full microglia repopulation.
Project description:Microglia, brain-resident macrophages, have been proposed to play an active role in synaptic refinement and maturation, influencing plasticity and circuit-level connectivity. Using a genetically modified mouse which lacks microglia (Csf1r ∆FIRE/∆FIRE), we investigate the effect on gene expression in particular cell types of the presence or absence of microglia in the developing mouse brain.
Project description:We assessed the roles of repopulating microglia in brain repair using mouse models. In this project, we show that removal of microglia from the mouse brain has little impact on the outcome of TBI but inducing the turnover of these cells through either pharmacologic or genetic approaches can yield a neuroprotective microglial phenotype that profoundly aids recovery. As a part of the experimental approaches, we perform bulk RNA sequencing experiments to unbiasedly profile the transcriptome of repopulating microglia. We identified unique gene signatures from repopulating microglia cells and infer how these cells modulate the microenvironment after TBI.
Project description:During early embryogenesis microglia arise from yolk sac progenitors populating the developing CNS, where they are maintained as tissue-resident macrophages throughout the organism’s lifespan. Here, we describe an experimental system that allows the specific conditional ablation of microglia in vivo. Strikingly, we found that the microglia compartment was reconstituted within one week following depletion. Microglia repopulation relied entirely on a CNS-resident, internal pool and was independent from bone marrow-derived precursors. Newly formed microglia were found in highly proliferative, organized micro-clusters that dissolve once steady state was achieved. Gene expression profiling revealed prominent expression of Interleukin-1 (IL-1) receptor in proliferating microglia. During the repopulation phase, IL-1 signaling was neutralized by treatment with IL-1 receptor antagonist that impaired microglia proliferation. Hence, microglia harbor a highly efficient potential to restore themselves without contribution of peripheral myeloid cells. IL-1 signaling significantly participates in this restorative proliferation process and is involved in stabilizing microglia maintenance. bone marrow macrophages, wild type microglia, and repopulating microglia
Project description:Microglia, brain resident macrophages, require instruction from the central nervous system microenvironment to maintain their identity, morphology, and to regulate inflammatory responses. We investigated the heterogeneity of response of microglia to the presence of neurons and astrocytes by performing single-cell sequencing of microglia in both monoculture, and in coculture with neurons and astrocytes.
Project description:Microglia are important immune cells in the brain. Microglia undergo a series of alterations during aging and increase the susceptibility to brain dysfunctions. However, the characteristics of microglia during the aging process are not fully understood. In this study, we mapped transcriptional and epigenetic profiles of microglia from 3- to 24-month-old mice. We observed unexpected gender divergences and identified age-dependent microglia (ADEM) genes in the aging process. We then compared characteristics between microglial aging and activation. To dissect the function of aged microglia excluding the influence from other aged brain cells, we established an accelerated microglial turnover model without directly affecting other brain cells. By this model, we achieved aged microglia in non-aged brains and confirmed that aged microglia per se contribute to cognitive decline. Collectively, we provide a comprehensive resource to decode the aging process of microglia, shedding light on how microglia maintain brain functions.
Project description:Single cell RNA sequencing analysis was performed on microglia isolated from brain slices (timepoints: 1 day, 1 week or 3 weeks in culture), 2D in vitro cultured microglia, and acutely isolated adult microglia. Differences in gene expression were examined to determine relative similarity to acutely isolated adult microglia.
Project description:Microglia, brain-resident macrophages, have been proposed to play an active role in synaptic refinement and maturation, influencing plasticity and circuit-level connectivity. Using a genetically modified mouse which lacks microglia (Csf1r ∆FIRE/∆FIRE), we investigate the effect on gene expression of the presence or absence of microglia in the developing mouse brain.
