Transcriptional Profiling of Hypoxic Neural Stem Cells to Identify Novel Regulators of Neural Stem Cell Biology
ABSTRACT: Neural stem cells reside in a hypoxic microenvironment within the brain. However, the crucial transcription factors that regulate neural stem cell biology under physiologic hypoxia are poorly understood. Here, we have performed microarray analysis of hypoxic versus normoxic neural stem cells with the aim of identifying pathways and transcription factors that are activated under oxygen concentrations mimicking normal brain tissue microenvironment. To identify the molecular mechanisms mediating the effect of low oxygen levels on NSC biology, we profiled the global effect of sustained, physiologic hypoxia on NSC gene expression using an unbiased approach by genome-wide microarray analysis. NSC were isolated from E13.5 mouse embryos (OF-1 strain) as previously described (Johe et al., 1996). After isolation, cells were immediately cultured at 37°C, 5% CO2 and either 5% or atmospheric (≈21%) oxygen and maintained in these conditions for 2-3 passages (minimum of 10 days). Then, total RNA was extracted, labeled and hybridized in a SurePrint G3 Mouse GE 8x60k array (Agilent Technologies). Four independent experiments were performed using different mouse donors for each experiment.
Project description:Neural stem cells (NSCs) reside in a hypoxic microenvironment within the brain. However, the crucial transcription factors (TFs) that regulate NSC biology under physiologic hypoxia are poorly understood. Here we have performed gene set enrichment analysis (GSEA) of microarray datasets from hypoxic versus normoxic NSCs with the aim of identifying pathways and TFs that are activated under oxygen concentrations mimicking normal brain tissue microenvironment. Integration of TF target (TFT) and pathway enrichment analysis identified the calcium-regulated TF NFATc4 as a major candidate to regulate hypoxic NSC functions. Nfatc4 expression was coordinately upregulated by top hypoxia-activated TFs, while NFATc4 target genes were enriched in hypoxic NSCs. Loss-of-function analyses further revealed that the calcineurin-NFATc4 signaling axis acts as a major regulator of NSC self-renewal and proliferation in vitro and in vivo by promoting the expression of TFs, including Id2, that contribute to the maintenance of the NSC state.
Project description:In the nervous system, neural stem cells (NSC) are necessary for the generation of new neurons and for cognitive function. Here we show that FoxO3, a member of a transcription factor family known to extend lifespan in invertebrates, regulates the NSC pool. We find that adult FoxO3-/- mice have fewer NSC in vivo than wild type counterparts. NSC isolated from adult FoxO3-/- mice have decreased self-renewal and an impaired ability to generate different neural lineages. Identification of the FoxO3-dependent gene expression profile in NSC suggests that FoxO3 regulates the NSC pool by inducing a program of genes that preserves quiescence, prevents premature differentiation, and controls oxygen metabolism. The ability of FoxO3 to prevent the premature depletion of NSC might have important implications for counteracting brain aging in long-lived species. Experiment Overall Design: mRNA expression from secondary neurospheres cultured from cells taken from mouse forebrains was compared between FoxO3+/+ (wildtype) and FoxO3-/- (null mutant) mice from the FVB/N background.
Project description:The neural stem cell (NSC) niche controls the expansion and differentiation of NSCs. Blood vessels are part of this neurogenic niche, but their functional significance for the regulation of NSC differentiation and the mechanisms involved remain unclear. Here, we report that blood vessel formation in the developing mouse and ferret cortex coincided with induction of NSC differentiation in time and space. Moreover, selective inhibition of brain angiogenesis in vessel-specific Gpr124 null embryos caused hypoxia and increased NSC expansion at the expense of differentiation. The hypoxia-inducible factor (HIF)-1Îą mediated this process, as the level of HIF-1Îą controlled NSC differentiation. Niche blood vessels regulated NSC differentiation at least in part by providing oxygen, as exposure to increased ambient oxygen levels rescued NSC differentiation in hypoxic brains of Gpr124 deficient embryos. Our findings establish a novel oxygen-dependent mechanism of how blood vessels regulate NSC differentiation.
Project description:Activated T cells inhibit neurogenesis in adult animal brain and cultured human fetal neural stem cells (NSC). However, the role of inhibition of neurogenesis in human neuroinflammatory diseases is still uncertain because of the difficulty in obtaining adult NSC from patients. Recent developments in cell reprogramming suggest that NSC may be derived directly from adult fibroblasts. We generated NSC from adult human peripheral CD34+ cells by transfecting the cells with Sendai virus constructs containing Sox-2, Oct3/4, C-MyC and Klf-4. The derived NSC could be differentiated to astroglia and action potential firing neurons. Co-culturing NSC with activated autologous T cells or treatment with recombinant granzyme B caused inhibition of neurogenesis as indicated by decreased NSC proliferation and neuronal differentiation. Thus, we have established a unique autologous in vitro model to study the pathophysiology of neuroinflammatory diseases that has potential for usage in personalized medicine. 11 Human samples from 7 sources representing 4 different cell types: 2 CD34 (CD34+ cells purified from adult peripheral blood), 3 iNS (induced Neural Stem Cells derived directly from CD34+ cells), 2 iNS derived from iPSC (Neural Stem cells differentiated from induced Pluripotent Stem Cells from CD34+ cells), 4 NPC (human primary cultured neural progenitor cells)
Project description:Transplantation of neural stem cells (NSCs) has been proposed as an alternative novel therapy to replace damaged neural circuitry after ischemic stroke onset. Nonetheless, albeit the potential of these cells for stroke therapy, many critical challenges are yet to be overcome to reach clinical applications. The major limitation of the NSC-based therapy is its inability to retain most of the donor stem cells after grafting into an ischemic brain area which is lacking of essential oxygen and nutrients for the survival of transplanted cells. Low cell survival rate limits the capacity of NSCs to repair the injured area and this poses a much more difficult challenge to the NSC-based therapy for ischemic stroke. In order to enhance the survival of transplanted cells, several stem cell culture preconditioning strategies have been employed. For ischemic diseases, hypoxic preconditioning is the most commonly applied strategy since the last few decades. Now, the preconditioning strategies have been developed and expanded enormously throughout years of efforts. This review systematically presented studies searched from PubMed, ScienceDirect, Web of Science, Scopus and the Google Scholar database up to 31 March 2020 based on search words containing the following terms: "precondition" or "pretreatment" and "neural stem cell" and "ischemic stroke". The searched data comprehensively reported seven major NSC preconditioning strategies including hypoxic condition, small drug molecules such as minocycline, doxycycline, interleukin-6, adjudin, sodium butyrate and nicorandil, as well as electrical stimulation using conductive polymer for ischemic stroke treatment. We discussed therapeutic benefits gained from these preconditioned NSC for in vitro and in vivo stroke studies and the detailed insights of the mechanisms underlying these preconditioning approaches. Nonetheless, we noticed that there was a scarcity of evidence on the efficacy of these preconditioned NSCs in human clinical studies, therefore, it is still too early to draw a definitive conclusion on the efficacy and safety of this active compound for patient usage. Thus, we suggest for more in-depth clinical investigations of this cell-based therapy to develop into more conscientious and judicious evidence-based therapy for clinical application in the future.
Project description:To identify Ceacam1 downstream factors, we compared gene expressions between NSCs and Ceacam1L-expressing NSC and between NSCL61 and Ceacam1shRNA-expressing NSCL61. We established Ceacam1L-expressing NSC and Ceacam1shRNA-expressing NSCL61s. We think that genes, which are differently expressed between NSC and Ceacam1L-NSC, and between NSCL61 and Ceacam1shRNA-NSCL61, are the Ceacam1 downstream factors.
Project description:Hypoxic brain injury remains a major source of neurodevelopmental impairment for both term and preterm infants. The perinatal period is a time of rapid transition in oxygen environments and developmental resetting of oxygen sensing. The relationship between neural oxygen sensing ability and hypoxic injury has not been studied. The oxygen sensing circuitry in the model organism C. elegans is well understood. We leveraged this information to investigate the effects of impairments in oxygen sensing on survival after anoxia. There was a significant survival advantage in developing worms specifically unable to sense oxygen shifts below their preferred physiologic range via genetic ablation of BAG neurons, which appear important for conferring sensitivity to anoxia. Oxygen sensing that is mediated through guanylate cyclases (gcy-31, 33, 35) is unlikely to be involved in conferring this sensitivity. Additionally, animals unable to process or elaborate neuropeptides displayed a survival advantage after anoxia. Based on these data, we hypothesized that elaboration of neuropeptides by BAG neurons sensitized animals to anoxia, but further experiments indicate that this is unlikely to be true. Instead, it seems that neuropeptides and signaling from oxygen sensing neurons operate through independent mechanisms, each conferring sensitivity to anoxia in wild type animals.
Project description:Neural stem cell (NSC) transplantation is an emerging strategy for restoring neuronal function in neurological disorders, such as Parkinson's disease (PD), which is characterized by a profound and selective loss of nigrostriatal dopaminergic (DA) neurons. Adult neurogenesis generates newborn neurons that can be observed at specialized niches where endothelial cells (ECs) play a significant role in regulating the behavior of NSCs, including self-renewal and differentiating into all neural lineage cells. In this minireview, we highlight the importance of establishing an appropriate microenvironment at the target site of NSC transplantation, where grafted cells integrate into the surroundings in order to enhance DA neurotransmission. Using a novel model of NSC-EC coculture, it is possible to combine ECs with NSCs, to generate such a neurovascular microenvironment. With appropriate NSCs selected, the composition of the transplant can be investigated through paracrine and juxtacrine signaling within the neurovascular unit (NVU). With target site cellular and acellular compartments of the microenvironment recognized, guided DA differentiation of NSCs can be achieved. As differentiated DA neurons integrate into the existing nigrostriatal DA pathway, the symptoms of PD can potentially be alleviated by reversing characteristic neurodegeneration.
Project description:Hypoxia-induced radioresistance is the primary reason for failure of tumor radiotherapy (RT). Changes within the irradiated tumor microenvironment (TME) including oxygen, reactive oxygen species (ROS) and nitric oxide (NO) are closely related to radioresistance. Therefore, there is an urgent need to develop new approaches for overcoming hypoxic radioresistance by incorporating TME regulation into current radiotherapeutic strategies.<h4>Methods</h4>Herein, we explored a radiation-responsive nanotheranostic system to enhance RT effects on hypoxic tumors by multi-way therapeutic effects. This system was developed by loading S-nitrosothiol groups (SNO, a NO donor) and indocyanine green (ICG, a photosensitizer) onto mesoporous silica shells of Eu<sup>3+</sup>-doped NaGdF<sub>4</sub> scintillating nanocrystals (NSC).<h4>Results</h4>Under X-ray radiation, this system can increase the local dosage by high-Z elements, promote ROS generation by X-ray-induced photodynamic therapy, and produce high levels of NO to enhance tumor-killing effects and improve hypoxia <i>via</i> NO-induced vasodilation. <i>In vitro</i> and <i>in vivo</i> studies revealed that this combined strategy can greatly reinforce DNA damage and apoptosis of hypoxic tumor cells, while significantly suppressing tumor growth, improving tumor hypoxia and promoting p53 up-regulation and HIF1? down-regulation. In addition, this system showed pronounced tumor contrast performance in T<sub>1</sub>-weighted magnetic resonance imaging and computed tomography.<h4>Conclusion</h4>This work demonstrates the great potential of scintillating nanotheranostics for multimodal imaging-guided X-ray radiation-triggered tumor combined therapy to overcome radioresistance.
Project description:Neurogenesis, the production of neural cell-types from neural stem cells (NSCs), occurs during development as well as within select regions of the adult brain. NSCs in the adult subependymal zone (SEZ) exist in a well-categorized niche microenvironment established by surrounding cells and their molecular products. The components of this niche maintain the NSCs and their definitive properties, including the ability to self-renew and multipotency (neuronal and glial differentiation).We describe a model in vitro NSC niche, derived from embryonic stem cells, that produces many of the cells and products of the developing subventricular zone (SVZ) and adult SEZ NSC niche. We demonstrate a possible role for apoptosis and for components of the extracellular matrix in the maintenance of the NSC population within our niche cultures. We characterize expression of genes relevant to NSC self-renewal and the process of neurogenesis and compare these findings to gene expression produced by an established neural-induction protocol employing retinoic acid.The in vitro NSC niche shows an identity that is distinct from the neurally induced embryonic cells that were used to derive it. Molecular and cellular components found in our in vitro NSC niche include NSCs, neural progeny, and ECM components and their receptors. Establishment of the in vitro NSC niche occurs in conjunction with apoptosis. Applications of this culture system range from studies of signaling events fundamental to niche formation and maintenance as well as development of unique NSC transplant platforms to treat disease or injury.