技术资料

Neural progenitor cells (NPCs) can be induced from somatic cells by defined factors. Here we report that NPCs can be generated from mouse embryonic fibroblasts by a chemical cocktail,namely VCR (V,VPA,an inhibitor of HDACs; C,CHIR99021,an inhibitor of GSK-3 kinases and R,Repsox,an inhibitor of TGF-β pathways),under a physiological hypoxic condition. These chemical-induced NPCs (ciNPCs) resemble mouse brain-derived NPCs re- garding their proliferative and self-renewing abilities,gene expression profiles,and multipotency for different neu- roectodermal lineages in vitro and in vivo. Further experiments reveal that alternative cocktails with inhibitors of histone deacetylation,glycogen synthase kinase,and TGF-β pathways show similar efficacies for ciNPC induction. Moreover,ciNPCs can also be induced from mouse tail-tip fibroblasts and human urinary cells with the same chemi- cal cocktail VCR. Thus our study demonstrates that lineage-specific conversion of somatic cells to NPCs could be achieved by chemical cocktails without introducing exogenous factors. View Publication

Undifferentiated pluripotent stem cells with flexible developmental potentials are not normally found in peripheral blood. However,such cells have recently been reported to reside in the bone marrow. Herein are reported methods of inducing pluripotency in cells derived from unmobilised adult human peripheral blood. In response to the inclusion of purified CR3/43 monoclonal antibody (mAb) to well-established culture conditions,mononuclear cells (MNC) obtained from a single blood donor are converted into pluripotent haematopoietic,neuronal and cardiomyogenic progenitor stem cells or undifferentiated stem cells. The haematopoietic stem cells are CD34+,clonogenic and have been shown to repopulate non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. The neuronal precursors transcribe the primitive stem cell markers OCT-4 and nestin,and on maturation,differentially stain positive for neuronal,glial or oligodendrocyte-specific antigens. The cardiomyogenic progenitor stem cells form large bodies of asynchronously beating cells and differentiate into mature cardiomyocytes which transcribe GATA-4. The undifferentiated stem cells do not express haematopoietic-associated markers,are negative for major histocompatibility complex (MHC) class I and II antigens,transcribe high levels of OCT-4 and form embryoid body (EB)-like structures. This induction of stem cell-like plasticity in MNC may have proceeded by a process of retrodifferentiation but,in any case,could have profound clinical and pharmacological implications. Finally,the flexibility and the speed by which a variety of stem cell classes can be generated ex vivo from donor blood could potentially transfer this novel process into a less invasive automated clinical procedure. View Publication

Multiple research groups have observed neuropathological phenotypes and molecular symptoms in vitro using induced pluripotent stem cell (iPSC)-derived neural cell cultures (i.e. patient-specific neurons and glia). However,the global differences/similarities that may exist between in vitro neural cells and their tissue-derived counterparts remain largely unknown. In this study,we compared temporal series of iPSC-derived in vitro neural cell cultures to endogenous brain tissue from the same autopsy donor. Specifically,we utilized RNA sequencing (RNA-Seq) to evaluate the transcriptional progression of in vitro-differentiated neural cells (over a timecourse of 0,35,70,105 and 140 days),and compared this with donor-identical temporal lobe tissue. We observed in vitro progression towards the reference brain tissue,and the following three results support this conclusion: (i) there was a significant increasing monotonic correlation between the days of our timecourse and the number of actively transcribed protein-coding genes and long intergenic non-coding RNAs (lincRNAs) (P < 0.05),consistent with the transcriptional complexity of the brain; (ii) there was an increase in CpG methylation after neural differentiation that resembled the epigenomic signature of the endogenous tissue; and (iii) there was a significant decreasing monotonic correlation between the days of our timecourse and the percent of in vitro to brain-tissue differences (P < 0.05) for tissue-specific protein-coding genes and all putative lincRNAs. Taken together,these results are consistent with in vitro neural development and physiological progression occurring predominantly by transcriptional activation of downregulated genes rather than deactivation of upregulated genes. View Publication

Stress bears a negative impact on adult neurogenesis. High levels of corticoids have been shown to inhibit neural stem cell proliferation,and are considered responsible for the loss of neural precursors. Their effects on the differentiation of the glial and neuronal lineages have been less studied. We examined the effect of dexamethasone (Dex),a synthetic glucocorticoid,on the differentiation of rat neural stem cells in vitro. Dex had no effect on the differentiation of cells cultured under standard conditions. Since we previously determined that NSC,when cultured under classical conditions,were deprived of polyunsaturated fatty acids (PUFA),and displayed phospholipid compositions very different from the in vivo figures [1],we examined the effect of Dex under PUFA supplementation. Dex impaired neuron and oligodendrocyte maturation in PUFA-supplemented cells,demonstrated by the reduction of neurite lengths and oligodendrocyte sizes. This effect was mediated by the glucocorticoid receptor (GR),since it was eliminated by mifepristone,a GR antagonist,and could be relayed by a reduction of ERK phosphorylation. We determined that GR was associated with PPAR β and α under basal conditions,and that this association was disrupted when PUFA were added in combination with Dex. We assumed that this effect on the receptor status enabled the effect of Dex on PUFA supplemented cells,since we determined that the binding to the glucocorticoid response element was higher in cells incubated with PUFA and Dex. In conclusion,corticoids can impair NSC differentiation,and consequently impact the entire process of neurogenesis. View Publication

Many neuropsychiatric disorders are thought to result from subtle changes in neural circuit formation. We used human embryonic stem cells and induced pluripotent stem cells (hiPSCs) to model mature,post-mitotic excitatory neurons and examine effects of fibroblast growth factor 2 (FGF2). FGF2 gene expression is known to be altered in brain regions of major depressive disorder (MDD) patients and FGF2 has anti-depressive effects in animal models of depression. We generated stable inducible neurons (siNeurons) conditionally expressing human neurogenin-2 (NEUROG2) to generate a homogenous population of post-mitotic excitatory neurons and study the functional as well as the transcriptional effects of FGF2. Upon induction of NEUROG2 with doxycycline,the vast majority of cells are post-mitotic,and the gene expression profile recapitulates that of excitatory neurons within 6 days. Using hES cell lines that inducibly express NEUROG2 as well as GCaMP6f,we were able to characterize spontaneous calcium activity in these neurons and show that calcium transients increase in the presence of FGF2. The FGF2-responsive genes were determined by RNA-Seq. FGF2-regulated genes previously identified in non-neuronal cell types were up-regulated (EGR1,ETV4,SPRY4,and DUSP6) as a result of chronic FGF2 treatment of siNeurons. Novel neuron-specific genes were also identified that may mediate FGF2-dependent increases in synaptic efficacy including NRXN3,SYT2,and GALR1. Since several of these genes have been implicated in MDD previously,these results will provide the basis for more mechanistic studies of the role of FGF2 in MDD. View Publication

Neuroinflammation is a common feature of acute neurological conditions such as stroke and spinal cord injury,as well as neurodegenerative conditions such as Parkinson's disease,Alzheimer's disease,and amyotrophic lateral sclerosis. Previous studies have demonstrated that acute neuroinflammation can adversely affect the survival of neural precursor cells (NPCs) and thereby limit the capacity for regeneration and repair. However,the mechanisms by which neuroinflammatory processes induce NPC death remain unclear. Microglia are key mediators of neuroinflammation and when activated to induce a pro-inflammatory state produce a number of factors that could affect NPC survival. Importantly,in the present study we demonstrate that tumor necrosis factor α (TNFα) produced by lipopolysaccharide-activated microglia is necessary and sufficient to trigger apoptosis in mouse NPCs in vitro. Furthermore,we demonstrate that microglia-derived TNFα induces NPC apoptosis via a mitochondrial pathway regulated by the Bcl-2 family protein Bax. BH3-only proteins are known to play a key role in regulating Bax activation and we demonstrate that microglia-derived TNFα induces the expression of the BH3-only family member Puma in NPCs via an NF-κB-dependent mechanism. Specifically,we show that NF-κB is activated in NPCs treated with conditioned media from activated microglia and that Puma induction and NPC apoptosis is blocked by the NF-κB inhibitor BAY-117082. Importantly,we have determined that NPC apoptosis induced by activated microglia-derived TNFα is attenuated in Puma-deficient NPCs,indicating that Puma induction is required for NPC death. Consistent with this,we demonstrate that Puma-deficient NPCs exhibit an 13-fold increase in survival as compared with wild-type NPCs following transplantation into the inflammatory environment of the injured spinal cord in vivo. In summary,we have identified a key signaling pathway that regulates neuroinflammation induced apoptosis in NPCs in vitro and in vivo that could be targeted to promote regeneration and repair in diverse neurological conditions. View Publication

Glioblastoma multiforme (GBM) is the most common and lethal adult brain tumor. Resistance to standard radiation and chemotherapy is thought to involve survival of GBM cancer stem cells (CSCs). To date,no single marker for identifying GBM CSCs has been able to capture the diversity of CSC populations,justifying the needs for additional CSC markers for better characterization. Employing targeted mass spectrometry,here we present five cell-surface markers HMOX1,SLC16A1,CADM1,SCAMP3,and CLCC1 which were found to be elevated in CSCs relative to healthy neural stem cells (NSCs). Transcriptomic analyses of REMBRANDT and TCGA compendiums also indicated elevated expression of these markers in GBM relative to controls and non-GBM diseases. Two markers SLC16A1 and HMOX1 were found to be expressed among pseudopalisading cells that reside in the hypoxic region of GBM,substantiating the histopathological hallmarks of GBM. In a prospective study (N%=%8) we confirmed the surface expression of HMOX1 on freshly isolated primary GBM cells (P0). Employing functional assays that are known to evaluate stemness,we demonstrate that elevated HMOX1 expression is associated with stemness in GBM and can be modulated through TGFβ. siRNA-mediated silencing of HMOX1 impaired GBM invasion-a phenomenon related to poor prognosis. In addition,surgical resection of GBM tumors caused declines (18%%±%5.1SEM) in the level of plasma HMOX1 as measured by ELISA,in 8/10 GBM patients. These findings indicate that HMOX1 is a robust predictor of GBM CSC stemness and pathogenesis. Further understanding of the role of HMOX1 in GBM may uncover novel therapeutic approaches. Stem Cells 2016;34:2276-2289. View Publication

Amyloid-ß (Aß) precursor protein (APP) metabolism engages neuronal endolysosomal pathways for Aß processing and secretion. In Alzheimer's disease (AD),dysregulation of APP leads to excess Aß and neuronal dysfunction; suggesting that neuronal APP/Aß trafficking can be targeted for therapeutic gain. Cathepsin B (CatB) is a lysosomal cysteine protease that can lower Aß levels. However,whether CatB-modulation of Aß improves learning and memory function deficits in AD is not known. To this end,progenitor neurons were infected with recombinant adenovirus expressing CatB and recovered cell lysates subjected to proteomic analyses. The results demonstrated Lamp1 deregulation and linkages between CatB and the neuronal phagosome network. Hippocampal injections of adeno-associated virus expressing CatB reduced Aß levels,increased Lamp1 and improved learning and memory. The findings were associated with the emergence of c-fos + cells. The results support the idea that CatB can speed Aß metabolism through lysosomal pathways and as such reduce AD-associated memory deficits. View Publication

Although neural stem cells (NSCs) sustain continuous neurogenesis throughout the adult lifespan of mammals,they progressively exhibit proliferation defects that contribute to a sharp reduction in subventricular neurogenesis during aging. However,little is known regarding the early age-related events in neurogenic niches. Using a fluorescence-activated cell sorting technique that allows for the prospective purification of the main neurogenic populations from the subventricular zone (SVZ),we demonstrated an early decline in adult neurogenesis with a dramatic loss of progenitor cells in 4 month-old young adult mice. Whereas the activated and quiescent NSC pools remained stable up to 12 months,the proliferative status of activated NSCs was already altered by 6 months,with an overall extension of the cell cycle resulting from a specific lengthening of G1. Whole genome analysis of activated NSCs from 2- and 6-month-old mice further revealed distinct transcriptomic and molecular signatures,as well as a modulation of the TGFβ signalling pathway. Our microarray study constitutes a cogent identification of new molecular players and signalling pathways regulating adult neurogenesis and its early modifications. View Publication

BACKGROUND In glioblastoma (GBM),Id1 serves as a functional marker for self-renewing cancer stem-like cells. We investigated the mechanism by which cyclooxygenase-2 (Cox-2)-derived prostaglandin E2 (PGE2) induces Id1 and increases GBM self-renewal and radiation resistance. METHODS Mouse and human GBM cells were stimulated with dimethyl-PGE2 (dmPGE2),a stabilized form of PGE2,to test for Id1 induction. To elucidate the signal transduction pathway governing the increase in Id1,a combination of short interfering RNA knockdown and small molecule inhibitors and activators of PGE2 signaling were used. Western blotting,quantitative real-time (qRT)-PCR,and chromatin immunoprecipitation assays were employed. Sphere formation and radiation resistance were measured in cultured primary cells. Immunohistochemical analyses were carried out to evaluate the Cox-2-Id1 axis in experimental GBM. RESULTS In GBM cells,dmPGE2 stimulates the EP4 receptor leading to activation of ERK1/2 MAPK. This leads,in turn,to upregulation of the early growth response1 (Egr1) transcription factor and enhanced Id1 expression. Activation of this pathway increases self-renewal capacity and resistance to radiation-induced DNA damage,which are dependent on Id1. CONCLUSIONS In GBM,Cox-2-derived PGE2 induces Id1 via EP4-dependent activation of MAPK signaling and the Egr1 transcription factor. PGE2-mediated induction of Id1 is required for optimal tumor cell self-renewal and radiation resistance. Collectively,these findings identify Id1 as a key mediator of PGE2-dependent modulation of radiation response and lend insight into the mechanisms underlying radiation resistance in GBM patients. View Publication

The potential ability to differentiate dedifferentiated adipocytes into a neural lineage is attracting strong interest as an emerging method of producing model cells for the treatment of a variety of neurological diseases. Here,we describe the efficient conversion of dedifferentiated adipocytes into a neural-like cell population. These cells grew in neurosphere-like structures and expressed a high level of the early neuroectodermal marker Nestin. These neurospheres could proliferate and express stemness genes,suggesting that these cells could be committed to the neural lineage. After neural induction,NeuroD1,Sox1,Double Cortin,and Eno2 were not expressed. Patch clamp data did not reveal different electrophysiological properties,indicating the inability of these cells to differentiate into mature neurons. In contrast,the differentiated cells expressed a high level of CLDN11,as demonstrated using molecular method,and stained positively for the glial cell markers CLDN11 and GFAP,as demonstrated using immunocytochemistry. These data were confirmed by quantitative results for glial cell line-derived neurotrophic factor production,which showed a higher secretion level in neurospheres and the differentiated cells compared with the untreated cells. In conclusion,our data demonstrate morphological,molecular,and immunocytochemical evidence of initial neural differentiation of mature adipocytes,committing to a glial lineage. View Publication

While no effective therapy is available for the treatment of methamphetamine (METH)-induced neurotoxicity,aerobic exercise is being proposed to improve depressive symptoms and substance abuse outcomes. The present study focuses on the effect of exercise on METH-induced aberrant neurogenesis in the hippocampal dentate gyrus in the context of the blood-brain barrier (BBB) pathology. Mice were administered with METH or saline by i.p. injections for 5 days with an escalating dose regimen. One set of mice was sacrificed 24 h post last injection of METH,and the remaining animals were either subjected to voluntary wheel running (exercised mice) or remained in sedentary housing (sedentary mice). METH administration decreased expression of tight junction (TJ) proteins and increased BBB permeability in the hippocampus. These changes were preserved post METH administration in sedentary mice and were associated with the development of significant aberrations of neural differentiation. Exercise protected against these effects by enhancing the protein expression of TJ proteins,stabilizing the BBB integrity,and enhancing the neural differentiation. In addition,exercise protected against METH-induced systemic increase in inflammatory cytokine levels. These results suggest that exercise can attenuate METH-induced neurotoxicity by protecting against the BBB disruption and related microenvironmental changes in the hippocampus. View Publication