Expression Of Olig2 Research Articles

Homeobox genes gain trimethylation of histone H3 lysine 4 in glioblastoma tissue.

Glioblastoma multiforme (GBM) exhibits considerable heterogeneity and associates with genome-wide alterations of the repressed chromatin marks DNA methylation and H3 lysine 27 trimethylation (H3K27me3). Tri-methylation on lysine 4 of histone H3 (H3K4me3) is an activating epigenetic mark that is enriched at promoter and promotes expression. It will be helpful in GBM diagnosis and treatment to identify the alteration of H3K4me3 between human GBM and GBM-surrounding tissues. Here, we performed an analysis using next-generation sequencing techniques to identify H3K4me3 modification in a case of GBM and the GBM-surrounding tissues. The results revealed a global decrease in H3K4me3 in GBM, especially at promoters and CpG islands. In GBM, homeobox genes gain H3K4me3, whereas the cell-cell adhesion-related cadherin genes lose H3K4me3. The products of the homeobox genes are highly connected with Ras-signalling and PI3K-Akt signalling pathways. Using The Cancer Genome Atlas (TCGA) data, we inferred the homeobox-regulated genes' expression is higher in 548 GBM cases than in 27 lower grade glioma cases giving that OLIG2 expression can be a reference. The results suggested that the H3K4me3 alteration is related to the formation and migration of GBM cells. We also found an extremely high reads count at epidermal growth factor receptor (EGFR) promoter, probably due to an amplification of copy number. Our analysis provides a case study about the change of H3K4me3 during shift to GBM.

Expression and function of Olig2 in eosinophils

Abstract Eosinophils are granulocytes that are associated with homeostasis and type 2 immune responses, allergy and parasitic infection. Olig2 is a basic helix loop helix transcription factor that is known to play a key role in cell fate decision and subsequent differentiation of oligodendrocytes. Herein, we report the expression and possible function of Olig2 in eosinophils. When cord blood (CB) CD34+ hematopoietic stem cells differentiated toward eosinophils during a 24 day culture period, Olig2 protein was expressed only in CB eosinophils at day 24, a time when these cells were considered fully differentiated and matured, while Olig2 protein was not detected at day 18 or at earlier time points. Olig2 protein was also abundantly expressed in human peripheral blood eosinophils, but not neutrophils, monocytes, lymphocytes or CB mast cells. RNA-seq analysis showed that numerous genes, especially those encoding eosinophil surface molecules, were highly upregulated along with OLIG2. Among the genes examined, SIGLEC-8 mRNA and protein were downregulated in parallel with OLIG2 by an Olig2 siRNA or a shRNA. In reporter gene and chromatin immunoprecipitation experiments, an E-box in the first intron was found to stimulate SIGLEC-8 gene transcription and bind Olig2. Occupancy of the E-box by Olig2 was also seen upon differentiation of immature eosinophilic AML14.3D10 cells. Hence, at least one important aspect of eosinophil differentiation is driven by Olig2, a transcription factor that has not previously been reported in normal granulocytes.

A Powerful CRISPR/Cas9-Based Method for Targeted Transcriptional Activation.

Targeted transcriptional activation of endogenous genes is important for understanding physiological transcriptional networks, synthesizing genetic circuits, and inducing cellular phenotype changes. The CRISPR/Cas9 system has great potential to achieve this purpose, however, it has not yet been successfully used to efficiently activate endogenous genes and induce changes in cellular phenotype. A powerful method for transcriptional activation by using CRISPR/Cas9 was developed. Replacement of a methylated promoter with an unmethylated one by CRISPR/Cas9 was sufficient to activate the expression of the neural cell gene OLIG2 and the embryonic stem cell gene NANOG in HEK293T cells. Moreover, CRISPR/Cas9-based OLIG2 activation induced the embryonic carcinoma cell line NTERA-2 to express the neuronal marker βIII-tubulin.

A Powerful CRISPR/Cas9‐Based Method for Targeted Transcriptional Activation

AbstractTargeted transcriptional activation of endogenous genes is important for understanding physiological transcriptional networks, synthesizing genetic circuits, and inducing cellular phenotype changes. The CRISPR/Cas9 system has great potential to achieve this purpose, however, it has not yet been successfully used to efficiently activate endogenous genes and induce changes in cellular phenotype. A powerful method for transcriptional activation by using CRISPR/Cas9 was developed. Replacement of a methylated promoter with an unmethylated one by CRISPR/Cas9 was sufficient to activate the expression of the neural cell gene OLIG2 and the embryonic stem cell gene NANOG in HEK293T cells. Moreover, CRISPR/Cas9‐based OLIG2 activation induced the embryonic carcinoma cell line NTERA‐2 to express the neuronal marker βIII‐tubulin.

Treatment Outcome and Prognostic Molecular Markers of Supratentorial Primitive Neuroectodermal Tumors.

BackgroundTo identify prognostic factors and define the optimal management of patients with supratentorial primitive neuroectodermal tumors (sPNETs), we investigated treatment outcomes and explored the prognostic value of specific molecular markers.MethodsA total of 47 consecutive patients with pathologically confirmed sPNETs between May 1985 and June 2012 were included. Immunohistochemical analysis of LIN28, OLIG2, and Rad51 expression was performed and correlated with clinical outcome.ResultsWith a median follow-up of 70 months, 5-year overall survival (OS) and progression-free survival (PFS) was 55.5% and 40%, respectively, for all patients. Age, surgical extent, and radiotherapy were significant prognostic factors for OS and PFS. Patients who received initially planned multimodal treatment without interruption (i.e., radiotherapy and surgery (≥subtotal resection), with or without chemotherapy) showed significantly higher 5-year OS (71.2%) and PFS (63.1%). In 29 patients with available tumor specimens, tumors with high expression of either LIN28 or OLIG2 or elevated level of Rad51 were significantly associated with poorer prognosis.ConclusionsWe found that multimodal treatment improved outcomes for sPNET patients, especially when radiotherapy and ≥subtotal resection were part of the treatment regimen. Furthermore, we confirmed the prognostic significance of LIN28 and OLIG2 and revealed the potential role of Rad51 in sPNETs.

Resveratrol Promotes Remyelination in Cuprizone Model of Multiple Sclerosis: Biochemical and Histological Study.

Multiple sclerosis (MS) is a demyelinating neurodegenerative disease, representing a major cause of neurological disability in young adults. Resveratrol is a stilbenoid polyphenol, known to pass blood brain barrier and exhibit antioxidant, anti-inflammatory, and neuroprotective effects in several brain injuries. Cuprizone model of MS is particularly beneficial in studying demyelination/remyelination. Our study examined the potential neuroprotective and pro-remyelination effects of resveratrol in cuprizone-intoxicated C57Bl/6 mice. Mice were fed with chow containing 0.7% cuprizone for 7days, followed by 3weeks on 0.2% cuprizone diet. Resveratrol (250mg/kg/day, p.o.) was given for 3weeks starting from the second week. At the end of the experiment, animals were tested on rotarod to evaluate changes in balance and motor coordination. Mice were then sacrificed to measure the brain content of glutathione, lipid peroxidation products, adenosine triphosphate, and phospho-inhibitory subunit of nuclear factor κB-α. The activities of cytochrome oxidase and superoxide dismutase were also assessed. The gene expression of myelin basic protein, 2',3'-cyclic nucleotide 3' phosphodiesterase, oligodendrocyte transcription factor-1 (Olig1), NF-κB p65 subunit, and tumor necrosis factor-α was also estimated. Luxol fast blue/periodic acid-Schiff stained brain sections were blindly scored to assess the myelin status. Resveratrol effectively enhanced motor coordination and balance, reversed cuprizone-induced demyelination, improved mitochondrial function, alleviated oxidative stress, and inhibited NF-κB signaling. Interestingly, resveratrol increased Olig1 expression that is positively correlated to active remyelination. The present study may be the first to indicate a pro-remyelinative effect for resveratrol which might represent a potential additive benefit in treating MS.

Brg1 directly regulates Olig2 transcription and is required for oligodendrocyte progenitor cell specification

The Olig2 basic-helix-loop-helix transcription factor promotes oligodendrocyte specification in early neural progenitor cells (NPCs), including radial glial cells, in part by recruiting SWI/SNF chromatin remodeling complexes to the enhancers of genes involved in oligodendrocyte differentiation. How Olig2 expression is regulated during oligodendrogliogenesis is not clear. Here, we find that the Brg1 subunit of SWI/SNF complexes interacts with a proximal Olig2 promoter and represses Olig2 transcription in the mouse cortex at E14, when oligodendrocyte progenitors (OPCs) are not yet found in this location. Brg1 does not interact with the Olig2 promoter in the E14 ganglionic eminence, where NPCs differentiate into Olig2-positive OPCs. Consistent with these findings, Brg1-null NPCs demonstrate precocious expression of Olig2 in the cortex. However, these cells fail to differentiate into OPCs. We further find that Brg1 is necessary for neuroepithelial-to-radial glial cell transition, but not neuronal differentiation despite a reduction in expression of the pro-neural transcription factor Pax6. Collectively, these and earlier findings support a model whereby Brg1 promotes neurogenic radial glial progenitor cell specification but is dispensable for neuronal differentiation. Concurrently, Brg1 represses Olig2 expression and the specification of OPCs, but is required for OPC differentiation and oligodendrocyte maturation.

Olig1 expression pattern in neural cells during rat spinal cord development.

PurposeOur purpose was to systematically investigate the expression pattern and role of Olig1 in neural cells during rat spinal cord development.Animals and methodsSpinal cord tissues were dissected from Sprague–Dawley rats at embryonic day 14.5 (E14.5) and E18.5, postnatal day 0 (P0), P3, P7, postnatal 2 weeks (P2W), P4W, and adults (more than 2 months after birth), respectively. The expression of Olig1 was determined by Western blot and immunostaining. To observe expression of Olig1 in different neural cell types, a double immunohistochemical staining was performed using antibodies against Olig1 with O4, β-tubulin, glial fibrillary acidic protein (GFAP), and myelin basic protein, respectively.ResultsThe expression of Olig1 protein shows a significant level change in rat spinal cord at different developmental time points. Starting with E14.5, the expression gradually increased and peaked at E18.5. Olig1 decreased gradually from P3 and reached its lowest level on P7. However, interestingly, the Olig1 expression increased again from P2W, until adulthood. Olig1 was coexpressed with O4-positive oligodendrocyte progenitor cells (OPCs) and β-tubulin-positive neurons at all time points during development. Olig1 was also coexpressed transiently with GFAP-positive astrocytes at only E14.5. Olig1 was localized in the cytoplasm of O4- and β-tubulin-positive cells during the period from E14.5 to adult.ConclusionThe expression of Olig1 in OPCs and neurons at all time points during development and in astrocytes at E14.5 suggests that Olig1 may play an important role in the generation and maturation of specific neural cells during development of spinal cord. Our results contribute to understanding the mechanism underlying developmental regulation of neural cells by Olig1.

Effect of Bushen Yisui Capsule () on oligodendrocyte lineage genes 1 and 2 in mice with experimental autoimmune encephalomyelitis.

To study the effects of Bushen Yisui Capsule (, BSYSC) on the oligodendrocyte lineage genes (Olig) 1 and Olig2 in C57BL/6 mice with experimental autoimmune encephalomyelitis (EAE) in order to explore the remyelination effect of BSYSC. The mice were randomly divided into normal control (NC), EAE model (EAE-M), prednisone acetate (PA, 6 mg/kg), BSYSC high-dose (3.02 g/kg) and BSYSC low-dose (1.51 g/kg) groups. The mice were induced by immunization with myelin oligodendrocyte glycoprotein (MOG) 35-55. The neurological function scores were assessed once daily. The pathological changes in mice brains were observed with hematoxylin-eosin (HE) staining and transmission electron microscope (TEM). The protein expressions of myelin basic protein (MBP), Olig1 and Olig2 in brains were measured by immunohistochemistry. The mRNA expressions of Olig1 and Olig 2 was also determined by quantitative real-time polymerase chain reaction. Compared with the EAE-M mice, (1) the neurological function scores were significantly decreased in BSYSC-treated mice on days 22 to 40 (P<0.01); (2) the inflammatory cells and demyelination in brains were reduced in BSYSC-treated EAE mice; (3) the protein expression of MBP was markedly increased in BSYSC-treated groups on day 18 and 40 respectively (P<0.05 or P<0.01); (4) the protein expression of Olig1 was increased in BSYSC (3.02 g/kg)-treated EAE mice on day 40 (P<0.01). Protein and mRNA expression of Olig2 was increased in BSYSC-treated EAE mice on day 18 and 40 (P<0.01). The effects of BSYSC on reducing demyelination and promoting remyelination might be associated with the increase of Olig1 and Olig2.

The clinicopathological features of pituicytoma and the differential diagnosis of sellar glioma.

Pituicytoma is rare and difficult to diagnose. This study explored the clinicopathological features, immunophenotype and differential diagnosis of pituicytoma. We compared 11 cases of pituicytoma and 26 cases of sellar glioma (16 pilocytic astrocytomas, four diffuse astrocytomas, three pilomyxoid astrocytomas, and three third ventricle chordoid gliomas). The 11 pituicytoma cases involved six men and five women (age: 33-65years). Three of the 11 patients experienced recurrence due to a residual tumor, and one patient underwent three surgeries during a 6-month period. Imaging findings revealed tumors were in the intrasellar region (four cases), suprasellar region (four cases) and intra-suprasellar regions (three cases). The tumor diameters were 1.3-3.8cm, and the preoperative diagnoses were pituitary adenoma, craniopharyngioma and meningioma. The tumors were solid and contained spindle or slightly chubby cells that were densely arranged with visible cleft-like or expanded sinusoid structures. The cells had vague boundaries, circular nuclei, fine chromatin, and a small nucleolus. Immunohistochemical staining of the pituicytomas revealed positive expression of thyroid transcription factor-1 (TTF-1) and S-100 protein (S-100), positive focal expression of glial GFAP;(five of 11 cases), and negative oligodendrocyte transcription factor 2 (Olig2), CD34 and neurofilament expression. The Ki67 index was 6% in one case and 1-2% in the other cases. Unlike pituicytoma, most sellar glioma cases exhibited GFAP and Olig2 expression, and negative TTF-1 expression. Third ventricle chordoid gliomas expressed TTF-1, GFAP and CD34, and were negative for Olig2. Our results indicate that pituicytoma typically involves dense arrangements of spindle or slightly chubby cells. The morphology is occasionally atypical, with ependymoma-like or meningioma-like structures, and occasionally exhibits pilomyxoid degeneration. Abundant sinusoids are characteristic of hemorrhagic tumors. The dense spindle cell arrangement is a relatively specific morphology, and staining for GFAP, TTF-1, Olig2 and CD4 may help differentiate pituicytoma from sellar glioma.

Expression of Lymphatic Markers in the Adult Rat Spinal Cord.

Under physiological conditions, lymphatic vessels are thought to be absent from the central nervous system (CNS), although they are widely distributed within the rest of the body. Recent work in the eye, i.e., another organ regarded as alymphatic, revealed numerous cells expressing lymphatic markers. As the latter can be involved in the response to pathological conditions, we addressed the presence of cells expressing lymphatic markers within the spinal cord by immunohistochemistry. Spinal cord of young adult Fisher rats was scrutinized for the co-expression of the lymphatic markers PROX1 and LYVE-1 with the cell type markers Iba1, CD68, PGP9.5, OLIG2. Rat skin served as positive control for the lymphatic markers. PROX1-immunoreactivity was detected in many nuclei throughout the spinal cord white and gray matter. These nuclei showed no association with LYVE-1. Expression of LYVE-1 could only be detected in cells at the spinal cord surface and in cells closely associated with blood vessels. These cells were found to co-express Iba1, a macrophage and microglia marker. Further, double labeling experiments using CD68, another marker found in microglia and macrophages, also displayed co-localization in the Iba1+ cells located at the spinal cord surface and those apposed to blood vessels. On the other hand, PROX1-expressing cells found in the parenchyma were lacking Iba1 or PGP9.5, but a significant fraction of those cells showed co-expression of the oligodendrocyte lineage marker OLIG2. Intriguingly, following spinal cord injury, LYVE-1-expressing cells assembled and reorganized into putative pre-vessel structures. As expected, the rat skin used as positive controls revealed classical lymphatic vessels, displaying PROX1+ nuclei surrounded by LYVE-1-immunoreactivity. Classical lymphatics were not detected in adult rat spinal cord. Nevertheless, numerous cells expressing either LYVE-1 or PROX1 were identified. Based on their localization and overlapping expression with Iba1, the LYVE-1+ cell population likely represents a macrophage subpopulation, while a significant fraction of PROX1+ cells belong to the oligodendrocytic lineage based on their distribution and the expression of OLIG2. The response of these LYVE-1+ and PROX1+ cell subpopulations to pathological conditions, especially in spinal cord inflammatory conditions, needs to be further elucidated.

Hdac3 Interaction with p300 Histone Acetyltransferase Regulates the Oligodendrocyte and Astrocyte Lineage Fate Switch

Establishment and maintenance of CNS glial cell identity ensures proper brain development and function, yet the epigenetic mechanisms underlying glial fate control remain poorly understood. Here, we show that the histone deacetylase Hdac3 controls oligodendrocyte-specification gene Olig2 expression and functions as a molecular switch for oligodendrocyte and astrocyte lineage determination. Hdac3 ablation leads to a significant increase of astrocytes with a concomitant loss of oligodendrocytes. Lineage tracing indicates that the ectopic astrocytes originate from oligodendrocyte progenitors. Genome-wide occupancy analysis reveals that Hdac3 interacts with p300 to activate oligodendroglial lineage-specific genes, while suppressing astroglial differentiation genes including NFIA. Furthermore, we find that Hdac3 modulates the acetylation state of Stat3 and competes with Stat3 for p300 binding to antagonize astrogliogenesis. Thus, our data suggest that Hdac3 cooperates with p300 to prime and maintain oligodendrocyte identity while inhibiting NFIA and Stat3-mediated astrogliogenesis, and thereby regulates phenotypic commitment at the point of oligodendrocyte-astrocytic fate decision.

NeuN+ neuronal nuclei in non-human primate prefrontal cortex and subcortical white matter after clozapine exposure

Increased neuronal densities in subcortical white matter have been reported for some cases with schizophrenia. The underlying cellular and molecular mechanisms remain unresolved.We exposed 26 young adult macaque monkeys for 6months to either clozapine, haloperidol or placebo and measured by structural MRI frontal gray and white matter volumes before and after treatment, followed by observer-independent, flow-cytometry-based quantification of neuronal and non-neuronal nuclei and molecular fingerprinting of cell-type specific transcripts.After clozapine exposure, the proportion of nuclei expressing the neuronal marker NeuN increased by approximately 50% in subcortical white matter, in conjunction with a more subtle and non-significant increase in overlying gray matter. Numbers and proportions of nuclei expressing the oligodendrocyte lineage marker, OLIG2, and cell-type specific RNA expression patterns, were maintained after antipsychotic drug exposure. Frontal lobe gray and white matter volumes remained indistinguishable between antipsychotic-drug-exposed and control groups.Chronic clozapine exposure increases the proportion of NeuN+ nuclei in frontal subcortical white matter, without alterations in frontal lobe volumes or cell type-specific gene expression. Further exploration of neurochemical plasticity in non-human primate brain exposed to antipsychotic drugs is warranted.

Analysis of Olig2 and YKL-40 expression: a clinicopathological/immunohistochemical study for the distinction between subventricular zone II and III glioblastomas.

Glioblastomas (GBs) are the most common and lethal primary brain tumors in the adults. Glioblastomas originates either from astrocytes that have accumulated mutations and de-differentiated or from neural stem cells within the subventricular zone (SVZ) in close contact with the vasculature. Recently, several studies have hypothesized that gliomagenesis occurs in perivascular niches with highly invasive peripheral proliferating zones. The purpose of our study was to investigate the pathological and clinical significance of Olig2 and YKL40 immunoexpression in 152 GBs in relationship to the SVZ II and III. Olig2 expressions were successfully detected in 12 (15.58%) of 77 SVZ type II GBs and 16 (21.3%) of 75 SVZ type III GBs, respectively. YKL-40 expression was observed in 45 (58.4%) of 77 SVZ type II GBs and in 17 (22.6%) of 75 SVZ type III GBs, respectively. Stepwise multivariate Cox proportional hazards models were used, and the prognostic factors to significantly impact OS were: PFS < 54 weeks (HR: 5.86; CI: 3.02-11.33; p = 0.00); radiotherapy (HR: 0.34; CI: 0.18-0.60; p = 0.00); radio- and chemotherapy (HR: 0.05; CI: 0.03-0.10; p = 0.0), and YKL-40+ GBs (HR: 1.61; CI: 1.28-2.31; p = 0.01).

SPACEFLIGHT EFFECTS ON GLIAL CELLS OF M4USE B0ONEMARROW.

Immunohistochmistrry was used to analyze lumbar enlarements in C57BL/76N mice on day 30 of a space flight with and w/o 7 day deadaptation to Earth. Space flown and non-deadpted mice had a increased number of S100B+ -cells in the cental channel zone and decreased population of GFAP astrocytes in ventral horns, Olig2+ cells in the corticospinal tract, PO+ -cells in vental horns and dorsal roots entry zone and Krox24+ -cells in ventral horns, dorsal roots entry zone and central channel zone, and reduced OSP fluorescence density in ventral channels. Elevated expression of myelin-producing Olig2, PO and Krox24 markers on day 7 of deadaptation implies recovery, significance of immunocytochemical changes in the myelin-producing cells in space flight, and suggests portentially rapid normalization of pathologic deviations in myelin fibers in consequence of sthe hypogravity motor syndrome.

Protective Effect of Electro-Acupuncture on Neural Myelin Sheaths Mediated through Activation of Epidermal Growth Factor Receptor after Compressed Spinal Cord Injury

Electro acupuncture has been widely used to treat demyelinating diseases, such as multiple sclerosis (MS), acute haemorrhagic leukoencephalitis (AHLE), compressed spinal cord injury (CSCI). However, the protective effect of electro acupuncture (EA) on neural myelin sheaths remains controversy attributed to the dimness of its therapeutic mechanism. In this study, we tried to explore the protective mechanism of EA in a custom-designed model of CSCI. Zusanli (ST36) and Huantiao (GB30) acupoints were stimulated by EA. The motor functions were monitored by Basso, Beattie and Bresnahanloco motor rating scale. The pathological changes in axonal myelinated fibers were estimated by luxol fast blue (LFB) and transmission electron microscopy (TEM). Epidermal growth factor receptor (EGFR), oligodendrocyte transcription factor 2 (Olig2), caspase-3 and phosphorylated Akt1 (pAkt1) were detected by immunofluorescence and western blot assays. After 7-day treatment of EA, the expression of p-EGFR, pAkt1 and Olig2 was significantly up-regulated which was consistent with changes of locomotor skill and ultrastructure of myelin sheath. By contrast, the expression of active caspase-3 was obviously down-regulated. Our results indicated that the protective effect of EA on neural myelin sheaths might be mediated via activation of EGFR after CSCI.

IL-1β induces hypomyelination in the periventricular white matter through inhibition of oligodendrocyte progenitor cell maturation via FYN/MEK/ERK signaling pathway in septic neonatal rats.

Neuroinflammation elicited by microglia plays a key role in periventricular white matter (PWM) damage (PWMD) induced by infectious exposure. This study aimed to determine if microglia-derived interleukin-1β (IL-1β) would induce hypomyelination through suppression of maturation of oligodendrocyte progenitor cells (OPCs) in the developing PWM. Sprague-Dawley rats (1-day old) were injected with lipopolysaccharide (LPS) (1 mg/kg) intraperitoneally, following which upregulated expression of IL-1β and IL-1 receptor 1 (IL-1R1 ) was observed. This was coupled with enhanced apoptosis and suppressed proliferation of OPCs in the PWM. The number of PDGFR-α and NG2-positive OPCs was significantly decreased in the PWM at 24 h and 3 days after injection of LPS, whereas it was increased at 14 days and 28 days. The protein expression of Olig1, Olig2, and Nkx2.2 was significantly reduced, and mRNA expression of Tcf4 and Axin2 was upregulated in the developing PWM after LPS injection. The expression of myelin basic protein (MBP) and 2',3'-cyclic-nucleotide 3"-phosphodiesterase (CNPase) was downregulated in the PWM at 14 days and 28 days after LPS injection; this was linked to reduction of the proportion of myelinated axons and thinner myelin sheath as revealed by electron microscopy. Primary cultured OPCs treated with IL-1β showed the failure of maturation and proliferation. Furthermore, FYN/MEK/ERK signaling pathway was involved in suppression of maturation of primary OPCs induced by IL-1β administration. Our results suggest that following LPS injection, microglia are activated and produce IL-1β in the PWM in the neonatal rats. Excess IL-1β inhibits the maturation of OPCs via suppression of FYN/MEK/ERK phosphorylation thereby leading to axonal hypomyelination.

Motor neurons and oligodendrocytes arise from distinct cell lineages by progenitor recruitment.

During spinal cord development, ventral neural progenitor cells that express the transcription factors Olig1 and Olig2, called pMN progenitors, produce motor neurons and then oligodendrocytes. Whether motor neurons and oligodendrocytes arise from common or distinct progenitors in vivo is not known. Using zebrafish, we found that motor neurons and oligodendrocytes are produced sequentially by distinct progenitors that have distinct origins. When olig2(+) cells were tracked during the peak period of motor neuron formation, most differentiated as motor neurons without further cell division. Using time-lapse imaging, we found that, as motor neurons differentiated, more dorsally positioned neuroepithelial progenitors descended to the pMN domain and initiated olig2 expression. Inhibition of Hedgehog signaling during motor neuron differentiation blocked the ventral movement of progenitors, the progressive initiation of olig2 expression, and oligodendrocyte formation. We therefore propose that the motor neuron-to-oligodendrocyte switch results from Hedgehog-mediated recruitment of glial-fated progenitors to the pMN domain subsequent to neurogenesis.

Presence of neural progenitors in spontaneous canine gliomas: A histopathological and immunohistochemical study of 20 cases

Gliomas are the most common primary brain tumours in humans and are associated with a poor prognosis. An accurate animal model of human glioma tumorigenesis is needed to test new treatment strategies. Dogs represent a promising model because they develop spontaneous diffusely-infiltrating gliomas. This study investigated whether spontaneous canine gliomas contain cancer stem cells previously identified in all grades of human gliomas.Twenty spontaneous cases of canine gliomas were graded according to the human WHO classification. The expression of different markers of lineage differentiation was evaluated with immunohistochemistry as follows: nestin and CD133 for neural stem cells, doublecortin for neuronal progenitor cells, Olig2 for glial progenitor cells, glial fibrillary acidic protein, vimentin and S-100 for mature glial cells, and NeuN and βIII-tubulin for mature neurons. Gliomas were characterised as follows: five grade II (oligodendrogliomas); nine grade III (seven anaplastic oligodendrogliomas, one anaplastic astrocytoma, one anaplastic oligoastrocytoma); six grade IV (glioblastomas).Immunohistochemical evaluation revealed that (1) nestin and CD133 were expressed in all grades of gliomas with a higher proportion of positive cells in high-grade gliomas; (2) the expression of S-100 protein and Olig2 did not differ substantially between astrocytic and oligodendroglial tumours, and (3) all gliomas were negative for mature neuron markers. The results demonstrated the presence of undifferentiated neural progenitors in all grades of spontaneous canine gliomas, confirming the relevance of this animal model for further studies on cancer stem cells.

Fibroblast Growth Factor-2 Enhanced The Recruitment of Progenitor Cells and Myelin Repair in Experimental Demyelination of Rat Hippocampal Formations.

Hippocampal insults have been observed in multiple sclerosis (MS) patients. Fibroblast growth factor-2 (FGF2) induces neurogenesis in the hippocampus and en- hances the proliferation, migration and differentiation of oligodendrocyte progenitor cells (OPCs). In the current study, we have investigated the effect of FGF2 on the processes of gliotoxin induced demyelination and subsequent remyelination in the hippocampus. In this experimental study adult male Sprague-Dawley rats re- ceived either saline or lysolecithin (LPC) injections to the right hippocampi. Animals re- ceived intraperitoneal (i.p.) injections of FGF2 (5 ng/g) on days 0, 5, 12 and 26 post-LPC. Expressions of myelin basic protein (Mbp) as a marker of myelination, Olig2 as a marker of OPC proliferation, Nestin as a marker of neural progenitor cells, and glial fibrillary acidic protein (Gfap) as a marker of reactive astrocytes were investigated in the right hippocampi by reverse transcriptase-polymerase chain reaction (RT-PCR). There was reduced Mbp expression at seven days after LPC injection, in- creased expressions of Olig2 and Nestin, and the level of Gfap did not change. FGF2 treatment reversed the expression level of Mbp to the control, significantly enhanced the levels of Olig2 and Nestin, but did not change the level of Gfap. At day-28 post- LPC, the expression level of Mbp was higher than the control in LPC-treated animals that received FGF2. The levels of Olig2, Nestin and Gfap were at the control level in the non-treated LPC group but significantly higher in the FGF2-treated LPC group. FGF2 enhanced hippocampal myelination and potentiated the recruitment of OPCs and neural stem cells (NSCs) to the lesion area. Long-term application of FGF2 might also enhance astrogliosis in the lesion site.