参考文献

OBJECTIVE Human tumor cell lines form the basis of the majority of present day laboratory cancer research. These models are vital to studying the molecular biology of tumors and preclinical testing of new therapies. When compared to traditional adherent cell lines,suspension cell lines recapitulate the genetic profiles and histologic features of glioblastoma multiforme (GBM) with higher fidelity. Using a modified neural stem cell culture technique,here we report the characterization of GBM cell lines including GBM variants. METHODS Tumor tissue samples were obtained intra-operatively and cultured in neural stem cell conditions containing growth factors. Tumor lines were characterized in vitro using differentiation assays followed by immunostaining for lineage-specific markers. In vivo tumor formation was assayed by orthotopic injection in nude mice. Genetic uniqueness was confirmed via short tandem repeat (STR) DNA profiling. RESULTS Thirteen oncosphere lines derived from GBM and GBM variants,including a GBM with PNET features and a GBM with oligodendroglioma component,were established. All unique lines showed distinct genetic profiles by STR profiling. The lines assayed demonstrated a range of in vitro growth rates. Multipotency was confirmed using in vitro differentiation. Tumor formation demonstrated histologic features consistent with high grade gliomas,including invasion,necrosis,abnormal vascularization,and high mitotic rate. Xenografts derived from the GBM variants maintained histopathological features of the primary tumors. CONCLUSIONS We have generated and characterized GBM suspension lines derived from patients with GBMs and GBM variants. These oncosphere cell lines will expand the resources available for preclinical study. View Publication

Glioblastoma multiforme (GBM) is the most common primary malignant adult brain tumor and is associated with poor survival. Recently,stem-like cell populations have been identified in numerous malignancies including GBM. To identify genes whose expression is changed with differentiation,we compared transcript profiles from a GBM oncosphere line before and after differentiation. Bioinformatic analysis of the gene expression profiles identified podocalyxin-like protein (PODXL),a protein highly expressed in human embryonic stem cells,as a potential marker of undifferentiated GBM stem-like cells. The loss of PODXL expression upon differentiation of GBM stem-like cell lines was confirmed by quantitative real-time PCR and flow cytometry. Analytical flow cytometry of numerous GBM oncosphere lines demonstrated PODXL expression in all lines examined. Knockdown studies and flow cytometric cell sorting experiments demonstrated that PODXL is involved in GBM stem-like cell proliferation and oncosphere formation. Compared to PODXL-negative cells,PODXL-positive cells had increased expression of the progenitor/stem cell markers Musashi1,SOX2,and BMI1. Finally,PODXL expression directly correlated with increasing glioma grade and was a marker for poor outcome in patients with GBM. In summary,we have demonstrated that PODXL is expressed in GBM stem-like cells and is involved in cell proliferation and oncosphere formation. Moreover,high PODXL expression correlates with increasing glioma grade and decreased overall survival in patients with GBM. View Publication

Growing evidence suggests that a physiological activity of the cellular prion protein (PrP(C)) plays a crucial role in several neurodegenerative disorders,including prion and Alzheimer's diseases. However,how the functional activity of PrP(C) is subverted to deliver neurotoxic signals remains uncertain. Transgenic (Tg) mice expressing PrP with a deletion of residues 105-125 in the central region (referred to as ΔCR PrP) provide important insights into this problem. Tg(ΔCR) mice exhibit neonatal lethality and massive degeneration of cerebellar granule neurons,a phenotype that is dose dependently suppressed by the presence of wild-type PrP. When expressed in cultured cells,ΔCR PrP induces large,ionic currents that can be detected by patch-clamping techniques. Here,we tested the hypothesis that abnormal ion channel activity underlies the neuronal death seen in Tg(ΔCR) mice. We find that ΔCR PrP induces abnormal ionic currents in neurons in culture and in cerebellar slices and that this activity sensitizes the neurons to glutamate-induced,calcium-mediated death. In combination with ultrastructural and biochemical analyses,these results demonstrate a role for glutamate-induced excitotoxicity in PrP-mediated neurodegeneration. A similar mechanism may operate in other neurodegenerative disorders attributable to toxic,β-rich oligomers that bind to PrP(C). View Publication

Classical lissencephaly is a genetic neurological disorder associated with mental retardation and intractable epilepsy,and Miller-Dieker syndrome (MDS) is the most severe form of the disease. In this study,to investigate the effects of MDS on human progenitor subtypes that control neuronal output and influence brain topology,we analyzed cerebral organoids derived from control and MDS-induced pluripotent stem cells (iPSCs) using time-lapse imaging,immunostaining,and single-cell RNA sequencing. We saw a cell migration defect that was rescued when we corrected the MDS causative chromosomal deletion and severe apoptosis of the founder neuroepithelial stem cells,accompanied by increased horizontal cell divisions. We also identified a mitotic defect in outer radial glia,a progenitor subtype that is largely absent from lissencephalic rodents but critical for human neocortical expansion. Our study,therefore,deepens our understanding of MDS cellular pathogenesis and highlights the broad utility of cerebral organoids for modeling human neurodevelopmental disorders. View Publication

There is emerging evidence that the commensal microbiota has a role in the pathogenesis of multiple sclerosis (MS),a putative autoimmune disease of the CNS. Here,we compared the gut microbial composition of 34 monozygotic twin pairs discordant for MS. While there were no major differences in the overall microbial profiles,we found a significant increase in some taxa such as Akkermansia in untreated MS twins. Furthermore,most notably,when transplanted to a transgenic mouse model of spontaneous brain autoimmunity,MS twin-derived microbiota induced a significantly higher incidence of autoimmunity than the healthy twin-derived microbiota. The microbial profiles of the colonized mice showed a high intraindividual and remarkable temporal stability with several differences,including Sutterella,an organism shown to induce a protective immunoregulatory profile in vitro. Immune cells from mouse recipients of MS-twin samples produced less IL-10 than immune cells from mice colonized with healthy-twin samples. IL-10 may have a regulatory role in spontaneous CNS autoimmunity,as neutralization of the cytokine in mice colonized with healthy-twin fecal samples increased disease incidence. These findings provide evidence that MS-derived microbiota contain factors that precipitate an MS-like autoimmune disease in a transgenic mouse model. They hence encourage the detailed search for protective and pathogenic microbial components in human MS. View Publication

Glioblastoma multiforme (GBM) is an aggressive,Grade IV astrocytoma with a poor survival rate,primarily due to the GBM tumor cells migrating away from the primary tumor site along the nanotopography of white matter tracts and blood vessels. It is unclear whether this nanotopography influences the biomechanical properties (i.e. cytoskeletal stiffness) of GBM tumor cells. Although GBM tumor cells have an innate propensity to migrate,we believe this capability is enhanced due to the influence of nanotopography on the tumor cells' biomechanical properties. In this study,we used an aligned nanofiber film that mimics the nanotopography in the tumor microenvironment to investigate the mechanical properties of GBM tumor cells in vitro. The data demonstrate that the cytoskeletal stiffness,cell traction stress,and focal adhesion area were significantly lower in the GBM tumor cells compared to healthy astrocytes. Moreover,the cytoskeletal stiffness was significantly reduced when cultured on aligned nanofiber films compared to smooth and randomly aligned nanofiber films. Gene expression analysis showed that tumor cells cultured on the aligned nanotopography upregulated key migratory genes and downregulated key proliferative genes. Therefore,our data suggest that the migratory potential is elevated when GBM tumor cells are migrating along aligned nanotopographical substrates. View Publication

Astrocyte phenotypes change in a process called reactive gliosis after traumatic central nervous system (CNS) injury. Astrogliosis is characterized by expansion of the glial fibrillary acidic protein (GFAP) cytoskeleton,adoption of stellate morphologies,and differential expression of some extracellular matrix molecules. The astrocytic response immediately after injury is beneficial,but in the chronic injury phase,reactive astrocytes produce inhibitory factors (i.e.,chondroitin sulfate proteoglycans [CSPGs]) that limit the regrowth of injured axons. There are no drugs that promote axon regeneration or functional recovery after CNS trauma in humans. To develop novel therapeutics for the injured CNS,we screened various libraries in a phenotypic assay to identify compounds that promote neurite outgrowth. However,the effects these compounds have on astrocytes are unknown. Specifically,we were interested in whether compounds could alter astrocytes in a manner that mimics the glial reaction to injury. To test this hypothesis,we developed cell-based phenotypic bioassays to measure changes in (1) GFAP morphology/localization and (2) CSPG expression/immunoreactivity from primary astrocyte cultures. These assays were optimized for six-point dose-response experiments in 96-well plates. The GFAP morphology assay is suitable for counter-screening with a Z-factor of 0.44±0.03 (mean±standard error of the mean; N=3 biological replicates). The CSPG assay is reproducible and informative,but does not satisfy common metrics for a screenable" assay. As proof of principle we tested a small set of hit compounds from our neurite outgrowth bioassay and identified one that can enhance axon growth without exacerbating the deleterious characteristics of reactive gliosis. View Publication

Regeneration of insulin-producing β-cells from resident pancreas progenitors requires an understanding of both progenitor identity and lineage plasticity. One model suggested that a rare β-cell sub-population within islets demonstrated multi-lineage plasticity. We hypothesized that β-cells from young mice (postnatal day 7,P7) exhibit such plasticity and used a model of islet dedifferentiation toward a ductal epithelial-cell phenotype to test this theory. RIPCre;Z/AP(+/+) mice were used to lineage trace the fate of β-cells during dedifferentiation culture by a human placental alkaline phosphatase (HPAP) reporter. There was a significant loss of HPAP-expressing β-cells in culture,but remaining HPAP(+) cells lost insulin expression while gaining expression of the epithelial duct cell marker cytokeratin-19 (Ck19). Flow cytometry and recovery of β-cell subpopulations from whole pancreas vs. islets suggest that the HPAP(+)Ck19(+) cells had derived from insulin-positive,glucose-transporter-2-low (Ins(+)Glut2(LO)) cells,representing 3.5% of all insulin-expressing cells. The majority of these cells were found outside of islets within clusters of <5 β-cells. These insulin(+)Glut2(LO) cells demonstrated a greater proliferation rate in vivo and in vitro as compared to insulin(+)Glut2(+) cells at P7,were retained into adulthood,and a subset differentiated into endocrine,ductal,and neural lineages,illustrating substantial plasticity. Results were confirmed using RIPCre;ROSA- eYFP mice. Quantitative PCR data indicated these cells possess an immature β-cell phenotype. These Ins(+)Glut2(LO) cells may represent a resident population of cells capable of forming new,functional β-cells,and which may be potentially exploited for regenerative therapies in the future. View Publication

Induced pluripotent stem cells have great potential as a human model system in regenerative medicine,disease modeling,and drug screening. However,their use in medical research is hampered by laborious reprogramming procedures that yield low numbers of induced pluripotent stem cells. For further applications in research,only the best,competent clones should be used. The standard assays for pluripotency are based on genomic approaches,which take up to 1 week to perform and incur significant cost. Therefore,there is a need for a rapid and cost-effective assay able to distinguish between pluripotent and nonpluripotent cells. Here,we describe a novel multiplexed,high-throughput,and sensitive peptide-based multiple reaction monitoring mass spectrometry assay,allowing for the identification and absolute quantitation of multiple core transcription factors and pluripotency markers. This assay provides simpler and high-throughput classification into either pluripotent or nonpluripotent cells in 7 min analysis while being more cost-effective than conventional genomic tests. View Publication

Asthma is highly prevalent,but current therapies cannot influence the chronic course of the disease. It is thus important to understand underlying early molecular events. In this study,we aimed to use microRNAs (miRNAs) - which are critical regulators of signaling cascades - to identify so far uncharacterized asthma pathogenesis pathways. Therefore,deregulation of miRNAs was assessed in whole lungs from mice with ovalbumin (OVA)-induced allergic airway inflammation (AAI). In silico predicted target genes were confirmed in reporter assays and in house-dust-mite (HDM) induced AAI and primary human bronchial epithelial cells (NHBE) cultured at the air-liquid interface. We identified and validated the transcription factor cAMP-responsive element binding protein (Creb1) and its transcriptional co-activators (Crtc1-3) as targets of miR-17,miR-144,and miR-21. Sec14-like 3 (Sec14l3) - a putative target of Creb1 - was down-regulated in both asthma models and in NHBE cells upon IL13 treatment,while it's expression correlated with ciliated cell development and decreased along with increasing goblet cell metaplasia. Finally,we propose that Creb1/Crtc1-3 and Sec14l3 could be important for early responses of the bronchial epithelium to Th2-stimuli. This study shows that miRNA profiles can be used to identify novel targets that would be overlooked in mRNA based strategies. View Publication