Host microbiota constantly control maturation and function of microglia in the central nervous system
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
SUBMITTER: Ori Staszewski
PROVIDER: E-GEOD-67858 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:As tissue macrophages of the central nervous system (CNS), microglia are critically involved in diseases of the CNS. However, it remains unknown what controls their maturation and activation under homeostatic conditions. Here we reveal significant contributions of the host microbiota to microglia homeostasis as germ-free (GF) mice displayed global defects in microglia with altered cell proportions and an immature phenotype leading to impaired innate immune responses. Temporal eradication of host microbiota severely changed microglia properties. Limited microbiota complexity also resulted in defective microglia. In contrast, recolonization with a complex microbiota partially restored microglia features. We determined that short-chain fatty acids (SCFA), microbiota-derived bacterial fermentation products, regulate microglia homeostasis. Accordingly, mice deficient for the SCFA receptor FFAR2 mirrored microglia defects found under GF conditions. These findings reveal that host bacteria vitally regulate microglia maturation and function, whereas microglia impairment can be restored to some extent by complex microbiota. We used microarrays to determine the gene expression of microglia after LCMV challenge. Lymphocytic Choriomeningitis Virus (LCMV) strain WE was propagated and titrated as plaque forming units (PFU) on L929 cells as described before (Herz,J. et al. Acid sphingomyelinase is a key regulator of cytotoxic granule secretion by primary T lymphocytes. Nat. Immunol. 10, 761-768 (2009)). PFU were multiplied by the factor 10 to be converted into infectious units (IU). Mice were infected by intracerebral inoculation of 103 IU into the right hemisphere.
2015-05-25 | E-GEOD-67857 | biostudies-arrayexpress
Project description:As tissue macrophages of the central nervous system (CNS), microglia are critically involved in diseases of the CNS. However, it remains unknown what controls their maturation and activation under homeostatic conditions. Here we reveal significant contributions of the host microbiota to microglia homeostasis as germ-free (GF) mice displayed global defects in microglia with altered cell proportions and an immature phenotype leading to impaired innate immune responses. Temporal eradication of host microbiota severely changed microglia properties. Limited microbiota complexity also resulted in defective microglia. In contrast, recolonization with a complex microbiota partially restored microglia features. We determined that short-chain fatty acids (SCFA), microbiota-derived bacterial fermentation products, regulate microglia homeostasis. Accordingly, mice deficient for the SCFA receptor FFAR2 mirrored microglia defects found under GF conditions. These findings reveal that host bacteria vitally regulate microglia maturation and function, whereas microglia impairment can be restored to some extent by complex microbiota. For acute inflammatory challenges, LPS was applied intracranially and 6 hours later, animals were analyzed. Control animals were injected PBS i.c. Transcriptional profiles of FACS-sorted microglia were assessed using Affymetrix® (Santa Clara, USA) GeneChip Arrays (Mouse Gene 2.1 ST Arrays).
2015-05-25 | E-GEOD-62201 | biostudies-arrayexpress
Project description:Recent studies have shown that tissue macrophages (MF) arise from embryonic progenitors of the yolk sac (YS) and fetal liver and colonize the tissues before birth. Further studies have proposed that developmentally distinct tissue MF can be identified based on the differential expression of F4/80 and CD11b, but whether a characteristic transcriptional profile exists is largely unknown. Here, we established an inducible fate mapping system that facilitated the identification of A2 progenitors of the YS as source of F4/80hi but not CD11bhi MF. Large-scale transcriptional profiling of MF precursors from the YS until adulthood allowed the description of a complex MF pedigree. We further identified a distinct molecular signature of F4/80hi and CD11bhi MF and found that Irf8 was vital for MF maturation and the innate immune response. Our data provide new cellular and molecular insights into the origin and developmental pathways of tissue MF. All samples are from mouse tissue at early developmental stages (E8, E9.5, E14) and from adulthood (6 weeks old). For the early developmental time points timed matings were performed. Macrophage populations were isolated from each tissue. RNA was isolated using Arcturus PicoPure isolation kit from yolk sac, brain, liver, kidney and skin samples after FACS sorting. Three replicates per cell population were included. Wildtype and Irf8 knockout samples were analyzed.
2016-07-28 | E-GEOD-73125 | biostudies-arrayexpress
Project description:WNT1/beta-catenin signaling plays a crucial role in the generation of mesodiencephalic dopaminergic (mdDA) neurons including the Substantia nigra pars compacta (SNc) subpopulation, whose degeneration is a hallmark of Parkinson’s Disease (PD). However, the precise functions of WNT/beta-catenin signaling in this context remain unknown. Using mutant mice, primary ventral midbrain (VM) cells and pluripotent stem cells (mouse embryonic stem cells and induced pluripotent stem cells), we show that Dickkopf 3 (DKK3), a secreted glycoprotein that modulates WNT/beta-catenin signaling, is specifically required for the correct differentiation of a rostrolateral mdDA precursor subset into SNc DA neurons. Dkk3 transcription in the murine VM coincides with the onset of mdDA neurogenesis and is required for the maintenance of LMX1A and consequently PITX3 expression in rostrolateral mdDA precursors, without affecting the proliferation or specification of their progenitors. Treatment of primary VM cells or differentiating pluripotent stem cells with recombinant WNT1 and/or DKK3 proteins consistently increases the proportion of mdDA cells with SNc DA neuron identity and promotes their survival in vitro. The SNc DA pro-differentiation and pro-survival properties of DKK3, together with its known anti-tumorigenic effect, therefore make it an ideal candidate for the improvement of regenerative and neuroprotective strategies in the treatment of PD. We performed gene expression microarray analysis on iPSC-derived and FACS-sorted GFP-positive Pitx3GFP/+ mdDA neurons, differentiated in the presence or absence of recombinant human WNT1 and recombinant human DKK3. In addition, we analysed primary and FACS-sorted GFP-positive Pitx3+/GFP mdDA neurons isolated from the E13.5 and E14.5 ventral midbrain of Pitx3+/GFP embryos
2015-08-22 | E-GEOD-58813 | biostudies-arrayexpress
Project description:The molecular mechanisms of neurogenic fate determination are of particular importance in light of the need to regenerate neurons. However the molecular logic of neurogenic fate determination is still ill understood, even though some key transcription factors have been implicated. Here we describe how one of these, the transcription factor Pax6, regulates adult neurogenesis by initiating a cross-regulatory network of 3 transcription factors executing neuronal fate and regulating genes required for neuronal differentiation. This network is initiated and driven to sufficiently high expression levels by the transcription factor Pax6 in close interaction with Brg1-containing SWI/SNF chromatin remodeling factors. Genetic deletion of either Pax6 or Brg1, the ATPase unit of the SWI/SNF complex, in neural stem cells of the adult mouse subependymal zone results in a fate conversion to distinct glial subtypes most pronounced when neuroblasts leave the neurogenic niche. Consistent with the phenocopy in vivo virtually all genes down-regulated by Brg1 deletion have Pax6-binding motifs. Amongst the few down-stream transcription factors are Sox11, Nfib and Brn4 that crossregulate each other and rescue neurogenesis also in direct reprogramming in the absence of Brg1 (or Pax6). Thus the function of Pax6-SWI/SNF is necessary and sufficient for neuronal fate maintenance and initiates a cross-regulatory effector network required for neuronal fate execution and maintenance to counteract glial differentiation in the adult brain. This identifies a novel role highly specific role of a chromatin-remodelling complex in stabilizing fate decisions in normal and forced neurogenesis. We performed gene expression microarray analysis on tissue derived from the SEZ or from the core region of the olfactory bulb from Brg1 cKO and control mice
2013-08-01 | E-GEOD-39362 | biostudies-arrayexpress
Project description:Despite the widespread interest in direct neuronal reprogramming, the mechanisms underpinning fate conversion remain largely unknown. Our study revealed a critical time point after which cells either successfully convert into neurons or succumb to cell death. Co-transduction with Bcl-2 greatly improved negotiation of this critical point by faster neuronal differentiation. Surprisingly, mutants with reduced or no affinity for Bax demonstrated that Bcl-2 exerts this effect by an apoptosis-independent mechanism. Consistent with a caspase-independent role, ferroptosis inhibitors potently increased neuronal reprogramming by inhibiting lipid peroxidation occurring during fate conversion. Genome-wide expression analysis confirmed that treatments promoting neuronal reprogramming elicit an anti-oxidative stress response. Importantly, coexpression of Bcl-2 and anti-oxidative treatments lead to an unprecedented improvement in glial-to-neuron conversion after traumatic brain injury in vivo, underscoring the relevance of these pathways in cellular reprograming irrespective of cell type, in vitro and in vivo. We performed gene expression microarray analysis on mouse embryonic fibroblasts transfected with a viral vector for Ascl1 or empty vector. Cells were then cultured in the absence or presence of forskolin
2016-06-29 | E-GEOD-70921 | biostudies-arrayexpress
Project description:Despite the widespread interest in direct neuronal reprogramming, the mechanisms underpinning fate conversion remain largely unknown. Our study revealed a critical time point after which cells either successfully convert into neurons or succumb to cell death. Co-transduction with Bcl-2 greatly improved negotiation of this critical point by faster neuronal differentiation. Surprisingly, mutants with reduced or no affinity for Bax demonstrated that Bcl-2 exerts this effect by an apoptosis-independent mechanism. Consistent with a caspase-independent role, ferroptosis inhibitors potently increased neuronal reprogramming by inhibiting lipid peroxidation occurring during fate conversion. Genome-wide expression analysis confirmed that treatments promoting neuronal reprogramming elicit an anti-oxidative stress response. Importantly, coexpression of Bcl-2 and anti-oxidative treatments lead to an unprecedented improvement in glial-to-neuron conversion after traumatic brain injury in vivo, underscoring the relevance of these pathways in cellular reprograming irrespective of cell type, in vitro and in vivo. We performed gene expression microarray analysis on mouse embryonic fibroblasts transfected with a viral vector for Ascl1 or empty vector. Cells were then cultured in the absence or presence of forskolin
2015-12-11 | E-GEOD-60790 | biostudies-arrayexpress
Project description:Insulin-dependent diabetes is a complex multifactorial disorder characterized by loss or dysfunction of β-cells. Pancreatic β-cells differ in size, glucose responsiveness, insulin secretion and precursor cell potential1-5, thus understanding the mechanisms underlying this functional heterogeneity might allow novel regenerative approaches. Here we discovered Flattop (Fltp) as a biomarker that distinguishes proliferative from mature β-cells. Genetic lineage tracing revealed that these β-cell subpopulations react differentially to environmental changes. Upon insulin resistance Fltp- β-cells undergo compensatory proliferation, whereas Fltp-lineage+ β-cells account for islet cell hypertrophy commonly associated with cytotoxic stress. The expression of the Wnt/planar cell polarity (PCP) effector gene Fltp increases when naïve β-cells cluster together to form polarized and mature three-dimensional (3D) islet mini-organs6-8. We show that dispersed early postnatal islet cells, insulinoma cells and human β-cells all have the intrinsic ability to form polarized pseudo-islets in 3D cultures. Compaction and polarization correlates with the induction of maturation markers and can be enhanced by Wnt/PCP pathway activation. Finally, we show that Fltp is not only a marker for mature β-cells, but is also functionally required for proper insulin secretion in mouse and human. We conclude that planar cell polarity and 3D architecture underlie functional β-cell heterogeneity and report that Fltp is a biomarker that separates proliferative from mature β-cells. These findings establish novel molecular underpinnings of β-cells and enable targeting of subpopulations for the regeneration of functional β-cell mass in diabetic patients. We performed gene expression microarray analysis on two FACS-sorted pancreatic islet cell populations: flattop-positive and flattop-negative.
2016-06-02 | E-GEOD-68853 | biostudies-arrayexpress
Project description:Objective: To study if diabetic and insulin-resistant states lead to mitochondrial dysfunction in the liver, or alternatively, if there is adaption of mitochondrial function to these states in the long-term range. Results: High-fat diet (HFD) caused insulin resistance and severe hepatic lipid accumulation, but respiratory chain parameters were unchanged. Livers from insulin-resistant IR/IRS-1+/- mice had normal lipid contents and normal respiratory chain parameters, however showed mitochondrial uncoupling. Livers from severely hyperglycemic and hypoinsulimic, streptozotocin (STZ)-treated mice had massively depleted lipid levels, but respiratory chain abundance was unchanged. However, their mitochondria showed increased abundance and activity of the respiratory chain, which was better coupled compared to controls. Conclusions: Insulin resistance, either induced by obesity or by genetic manipulation, does not cause mitochondrial dysfunction in the liver of mice. However, severe insulin deficiency and high blood glucose levels in mice cause an enhanced performance of the respiratory chain, probably in order to maintain the high energy requirement of the unsuppressed gluconeogenesis. We performed gene expression microarray analysis on liver tissue derived from mice treated with STZ or standard diet (control).
2013-12-10 | E-GEOD-39752 | biostudies-arrayexpress
Project description:Evolution of the mammalian brain encompassed a remarkable increase in size of cerebral cortex, including tangential and radial expansion, but the mechanisms underlying these key parameters are still largely unknown. Here, we identified the novel DNA associated protein TRNP1 as a regulator of cerebral cortical expansion in both these dimensions. Gain and loss of function experiments in the mouse cerebral cortex in vivo demonstrate that high Trnp1 levels promote neural stem cell self-renewal and tangential expansion, while lower levels promote radial expansion resulting in a potent increase in the generation of intermediate progenitors and outer radial glial cells resulting in folding of the otherwise smooth murine cerebral cortex. Remarkably, TRNP1 expression levels exhibit regional differences also in the cerebral cortex of human fetuses anticipating radial or tangential expansion respectively. Thus, the dynamic regulation of TRNP1 is critical to regulate tangential and radial expansion of the cerebral cortex in mammals. We performed gene expression microarray analysis on embryonic mouse cerebral cortex derived from Trnp1 knockdown and control animals.
2013-04-26 | E-GEOD-40582 | biostudies-arrayexpress