搜索结果: 'NeuroCult Proliferation'

The prion protein (PrP) is highly conserved and ubiquitously expressed,suggesting that it plays an important physiological function. However,despite decades of investigation,this role remains elusive. Here,by using animal and cellular models,we unveil a key role of PrP in the DNA damage response. Exposure of neurons to a genotoxic stress activates PRNP transcription leading to an increased amount of PrP in the nucleus where it interacts with APE1,the major mammalian endonuclease essential for base excision repair,and stimulates its activity. Preventing the induction of PRNP results in accumulation of abasic sites in DNA and impairs cell survival after genotoxic treatment. Brains from Prnp(-/-) mice display a reduced APE1 activity and a defect in the repair of induced DNA damage in vivo. Thus,PrP is required to maintain genomic stability in response to genotoxic stresses. View Publication

The ability of high-risk neuroblastoma to survive unfavorable growth conditions and multimodal therapy has produced an elusive childhood cancer with remarkably poor prognosis. A novel phenomenon enabling neuroblastoma to survive selection pressure is its capacity for reversible adaptive plasticity. This plasticity allows cells to transition between highly proliferative anchorage dependent (AD) and slow growing,anoikis-resistant anchorage independent (AI) phenotypes. Both phenotypes are present in established mouse and human tumors. The differential gene expression profile of the two cellular phenotypes in the mouse Neuro2a cell line delineated pathways of proliferation in AD cells or tyrosine kinase activation/ apoptosis inhibition in AI cells. A 20 fold overexpression of inhibitor of differentiation 2 (Id2) was identified in AD cells while up-regulation of genes involved in anoikis resistance like PI3K/Akt,Erk,Bcl2 and integrins was observed in AI cells. Similarly,differential expression of Id2 and other genes of interest were also observed in the AD and AI phenotypes of human neuroblastoma cell lines,SK-N-SH and IMR-32; as well as in primary human tumor specimens. Forced down-regulation of Id2 in AD cells or overexpression in AI cells induced the cells to gain characteristics of the other phenotype. Id2 binds both TGFβ and Smad2/3 and appears critical for maintaining the proliferative phenotype at least partially through negative regulation of the TGFβ/Smad pathway. Simultaneously targeting the differential molecular pathways governing reversible adaptive plasticity resulted in 50% cure of microscopic disease and delayed tumor growth in established mouse neuroblastoma tumors. We present a mechanism that accounts for reversible adaptive plasticity and a molecular basis for combined targeted therapies in neuroblastoma. View Publication

Glioblastoma (GBM) is a common and malignant tumor with a poor prognosis. Glioblastoma stem cells (GSCs) have been reported to be involved in tumorigenesis,tumor maintenance and therapeutic resistance. Thus,to discover novel candidate therapeutic drugs for anti-GBM and anti-GSCs is an urgent need. We hypothesized that if treatment with a drug could reverse,at least in part,the gene expression signature of GBM and GSCs,this drug may have the potential to inhibit pathways essential in the formation of GBM and thereby treat GBM. Here,we collected 356 GBM gene signatures from public databases and queried the Connectivity Map. We systematically evaluated the in vitro antitumor effects of 79 drugs in GBM cell lines. Of the drugs screened,thioridazine was selected for further characterization because it has potent anti-GBM and anti-GSCs properties. When investigating the mechanisms underlying the cytocidal effects of thioridazine,we found that thioridazine induces autophagy in GBM cell lines,and upregulates AMPK activity. Moreover,LC3-II was upregulated in U87MG sphere cells treated with thioridazine. In addition,thioridazine suppressed GBM tumorigenesis and induced autophagy in vivo. We not only repurposed the antipsychotic drug thioridazine as a potent anti-GBM and anti-GSCs agent,but also provided a new strategy to search for drugs with anticancer and anticancer stem cell properties. View Publication

BACKGROUND The molecular mechanisms that determine social behavior are poorly understood. Pheromones play a critical role in social recognition in most animals,including mice,but how these are converted into behavioral responses is largely unknown. Here,we report that the absence of the small GTPase M-Ras affects social behavior in mice. RESULTS In their interactions with other males,Mras(-/-) males exhibited high levels of territorial aggression and social investigations,and increased fear-related behavior. They also showed increased mating behavior with females. Curiously,increased aggression and mating behaviors were only observed when Mras(-/-) males were paired with Mras(-/-) partners,but were significantly reduced when paired with wild-type (WT) mice. Since mice use pheromonal cues to identify other individuals,we explored the possibility that pheromone detection may be altered in Mras(-/-) mice. Unlike WT mice,Mras(-/-) did not show a preference for exploring unfamiliar urinary pheromones or unfamiliar isogenic mice. Although this could indicate that vomeronasal function and/or olfactory learning may be compromised in Mras(-/-) mice,these observations were not fully consistent with the differential behavioral responses to WT and Mras(-/-) interaction partners by Mras(-/-) males. In addition,induction of c-fos upon pheromone exposure or in response to mating was similar in WT and Mras (-/-) mice,as was the ex vivo expansion of neural progenitors with EGF. This indicated that acute pheromone detection and processing was likely intact. However,urinary metabolite profiles differed between Mras(-/-) and WT males. CONCLUSIONS The changes in behaviors displayed by Mras(-/-) mice are likely due to a complex combination of factors that may include an inherent predisposition to increased aggression and sexual behavior,and the production of distinct pheromones that could override the preference for unfamiliar social odors. Olfactory and/or social learning processes may thus be compromised in Mras(-/-) mice. View Publication

Glioblastomas (GBMs) are highly aggressive,invasive brain tumors with bad prognosis and unmet medical need. These tumors are heterogeneous being constituted by a variety of cells in different states of differentiation. Among these,cells endowed with stem properties,tumor initiating/propagating properties and particularly resistant to chemo- and radiotherapies are designed as the real culprits for tumor maintenance and relapse after treatment. These cells,termed cancer stem-like cells,have been designed as prominent targets for new and more efficient cancer therapies. G-protein coupled receptors (GPCRs),a family of membrane receptors,play a prominent role in cell signaling,cell communication and crosstalk with the microenvironment. Their role in cancer has been highlighted but remains largely unexplored. Here,we report a descriptive study of the differential expression of the endo-GPCR repertoire in human glioblastoma cancer stem-like cells (GSCs),U-87 MG cells,human astrocytes and fetal neural stem cells (f-NSCs). The endo-GPCR transcriptome has been studied using Taqman Low Density Arrays. Of the 356 GPCRs investigated,138 were retained for comparative studies between the different cell types. At the transcriptomic level,eight GPCRs were specifically expressed/overexpressed in GSCs. Seventeen GPCRs appeared specifically expressed in cells with stem properties (GSCs and f-NSCs). Results of GPCR expression at the protein level using mass spectrometry and proteomic analysis are also presented. The comparative GPCR expression study presented here gives clues for new pathways specifically used by GSCs and unveils novel potential therapeutic targets. View Publication

BACKGROUND Transplanting autologous patient-derived enteric neuronal stem/progenitor cells (ENSCs) is an innovative approach to replacing missing enteric neurons in patients with Hirschsprung disease (HSCR). Using autologous cells eliminates immunologic and ethical concerns raised by other cell sources. However,whether postnatal aganglionic bowel is permissive for transplanted ENSCs and whether ENSCs from HSCR patients can be successfully isolated,cultured,and transplanted in vivo remains unknown. METHODS ENSCs isolated from the ganglionic intestine of Ednrb(-/-) mice (HSCR-ENSCs) were characterized immunohistochemically and evaluated for their capacity to proliferate and differentiate in vitro. Fluorescently labeled ENSCs were co-cultured ex vivo with aganglionic Ednrb(-/-) colon. For in vivo transplantation,HSCR-ENSCs were labeled with lentivirus expressing green fluorescent protein (GFP) and implanted into aganglionic embryonic chick gut in ovo and postnatal aganglionic Ednrb(-/-) rectum in vivo. KEY RESULTS HSCR-ENSCs maintain normal capacity self-renewal and neuronal differentiation. Moreover,the Ednrb(-/-) aganglionic environment is permissive to engraftment by wild-type ENSCs ex vivo and supports migratrion and neuroglial differentiation of these cells following transplantation in vivo. Lentiviral GFP-labeled HSCR-ENSCs populated embryonic chick hindgut and postnatal colon of Ednrb(-/-) HSCR,with cells populating the intermuscular layer and forming enteric neurons and glia. CONCLUSIONS & INFERENCES ENSCs can be isolated and cultured from mice with HSCR,and transplanted into the aganglionic bowel of HSCR littermates to generate enteric neuronal networks. These results in an isogenic model establish the potential of using autologous-derived stem cells to treat HSCR and other intestinal neuropathies. View Publication

The identification of neural stem cells (NSCs) in situ has been prevented by the inability to identify a marker consistently expressed in all adult NSCs and is thus generally accomplished using the in vitro neurosphere-forming assay. The high-mobility group transcription factor Sox2 is expressed in embryonic neural epithelial stem cells; because these cells are thought to give rise to the adult NSC population,we hypothesized that Sox2 may continue to be expressed in adult NSCs. Using Sox2:EGFP transgenic mice,we show that Sox2 is expressed in neurogenic regions along the rostral-caudal axis of the central nervous system throughout life. Furthermore,all neurospheres derived from these neurogenic regions express Sox2,suggesting that Sox2 is indeed expressed in adult NSCs. We demonstrate that NSCs are heterogeneous within the adult brain,with differing capacities for cell production. In vitro,all neurospheres express Sox2,but the expression of markers common to early progenitor cells within individual neurospheres varies; this heterogeneity of NSCs is mirrored in vivo. For example,both glial fibrillary acidic protein and NG2 are expressed within individual neurospheres,but their expression is mutually exclusive; likewise,these two markers show distinct staining patterns within the Sox2+ regions of the brain's neurogenic regions. Thus,we propose that the expression of Sox2 is a unifying characteristic of NSCs in the adult brain,but that not all NSCs maintain the ability to form all neural cell types in vivo. View Publication

Caspase proteases have become the focal point for the development and application of anti-apoptotic therapies in a variety of central nervous system diseases. However,this approach is based on the premise that caspase function is limited to invoking cell death signals. Here,we show that caspase-3 activity is elevated in nonapoptotic differentiating neuronal cell populations. Moreover,peptide inhibition of protease activity effectively inhibits the differentiation process in a cultured neurosphere model. These results implicate caspase-3 activation as a conserved feature of neuronal differentiation and suggest that targeted inhibition of this protease in neural cell populations may have unintended consequences. View Publication

We determined the embryonic origins of adult forebrain subventricular zone (SVZ) stem cells by Cre-lox fate mapping in transgenic mice. We found that all parts of the telencephalic neuroepithelium,including the medial ganglionic eminence and lateral ganglionic eminence (LGE) and the cerebral cortex,contribute multipotent,self-renewing stem cells to the adult SVZ. Descendants of the embryonic LGE and cortex settle in ventral and dorsal aspects of the dorsolateral SVZ,respectively. Both populations contribute new (5-bromo-2'-deoxyuridine-labeled) tyrosine hydroxylase- and calretinin-positive interneurons to the adult olfactory bulb. However,calbindin-positive interneurons in the olfactory glomeruli were generated exclusively by LGE-derived stem cells. Thus,different SVZ stem cells have different embryonic origins,colonize different parts of the SVZ,and generate different neuronal progeny,suggesting that some aspects of embryonic patterning are preserved in the adult SVZ. This could have important implications for the design of endogenous stem cell-based therapies in the future. View Publication

Microtubule-associated protein (MAP) 2 has been perceived as a static cytoskeletal protein enriched in neuronal dendritic shafts. Emerging evidence indicates dynamic functions for various MAPs in activity-dependent synaptic plasticity. However,it is unclear how MAP2 is associated with synaptic plasticity mechanisms. Here,we demonstrate that specific silencing of high-molecular-weight MAP2 in vivo abolished induction of long-term potentiation (LTP) in the Schaffer collateral pathway of CA1 pyramidal neurons and in vitro blocked LTP-induced surface delivery of AMPA receptors and spine enlargement. In mature hippocampal neurons,we observed rapid translocation of a subpopulation of MAP2,present in dendritic shafts,to spines following LTP stimulation. Time-lapse confocal imaging showed that spine translocation of MAP2 was coupled with LTP-induced spine enlargement. Consistently,immunogold electron microscopy revealed that LTP stimulation of the Schaffer collateral pathway promoted MAP2 labeling in spine heads of CA1 neurons. This translocation depended on NMDA receptor activation and Ras-MAPK signaling. Furthermore,LTP stimulation led to an increase in surface-expressed AMPA receptors specifically in the neurons with MAP2 spine translocation. Altogether,this study indicates a novel role for MAP2 in LTP mechanisms and suggests that MAP2 participates in activity-dependent synaptic plasticity in mature hippocampal networks. View Publication