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Oligodendrocyte Differentiation (oligodendrocyte + differentiation)
Selected Abstracts,IV tubulin is selectively expressed by oligodendrocytes in the central nervous systemGLIA, Issue 3 2005Nobuo Terada Abstract Oligodendrocyte differentiation and myelination involve dramatic changes in cell signaling pathways, gene expression patterns, cell shape, and cytoskeletal organization. In a pilot study investigating CNS angiogenesis, oligodendrocytes were intensely labeled by antisera directed against the C-terminal of Tie-2, a 140-kDa transmembrane receptor for angiopoietin. Immunoprecipitation of rat brain proteins with Tie-2 C-terminal antisera, however, produced a single spot of ,55-kDa pI ,5 by two-dimensional (2D) electrophoresis, which was identified as ,-tubulin by mass spectrometry. Isotype-specific antibodies for ,IV tubulin selectively labeled oligodendrocytes. First detected in premyelinating oligodendrocytes, ,IV tubulin was abundant in myelinating oligodendrocyte perinuclear cytoplasm and processes extending to and along developing myelin internodes. ,IV tubulin-positive MTs were diffusely distributed in oligodendrocyte perinuclear cytoplasm and not organized around the centrosome. ,IV tubulin may play a role in establishing the oligodendrocyte MT network, which is essential for the transport of myelin proteins, lipids, and RNA during myelination. © 2005 Wiley-Liss, Inc. [source] Endothelial cell-derived bone morphogenetic proteins regulate glial differentiation of cortical progenitorsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2008Tetsuya Imura Abstract Gliogenesis is an important component of cortical development during the postnatal period. Two macroglial cells are generated in a particular order, i.e. astrocytes first and oligodendrocytes later. The mechanisms underlying this sequence of glial differentiation are unknown but interactions with blood vessels are postulated to play a role. We show, using a mouse in-vitro coculture system, that endothelial cells promote astrocyte differentiation but inhibit oligodendrocyte differentiation of postnatal cortical progenitors. Endothelial cells produce bone morphogenetic proteins (BMPs) to activate Sma- and Mad-related protein (Smad) signalling in progenitors and the effects of endothelial cells on glial differentiation are blocked by the BMP antagonist Noggin. Differentiation of progenitors into astrocytes results in the inhibition of endothelial cell growth, accompanied by changes in gene expression of angiogenic factors, indicating bidirectional interactions between progenitors and endothelial cells. In vivo, Smad signalling is activated in various types of cortical cells including progenitors in association with astrogenesis but is inactivated before the peak of oligodendrogenesis. Capillary vessels isolated from the developing cortex express high levels of BMPs. Together, these results demonstrate that endothelial cells regulate glial differentiation by secreting BMPs in vitro and suggest a similar role in cortical gliogenesis in vivo. [source] Delay of myelin formation in arylsulphatase A-deficient miceEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2005Afshin Yaghootfam Abstract Metachromatic leukodystrophy (MLD) is a lysosomal storage disorder caused by the deficiency of arylsulphatase A (ASA). This leads to the accumulation of the sphingolipid 3-O-sulphogalactosylceramide (sulphatide) and progressive demyelination in the nervous system of MLD patients. The mechanisms and development of pathology in the disease are still largely unknown. In this study we investigate how the inability to degrade sulphatide affects the formation of myelin in ASA-deficient (ASA,/,) mice. In mice at 2 weeks of age there was a substantial reduction in myelin basic protein (MBP) mRNA and protein. This was confirmed by an immunohistochemical analysis. MBP mRNA and protein, however, reach normal levels at 3 weeks of age. Proteolipid protein (PLP) and MAL mRNA were also reduced in ASA,/, mice at 2 weeks of age; whereas the level of PLP mRNA was normal at 26 weeks of age, MAL mRNA expression remained reduced up to this age. In situ hybridization revealed no significant changes in the number of myelinating oligodendrocytes or oligodendrocyte precursor cells in ASA,/, mice. These results suggest that oligodendrocyte differentiation was normal in ASA,/, mice. No differences were found in the expression of the sulphatide synthesizing enzymes cerebroside sulphotransferase and UDP-galactose : ceramide galactosyltransferase. Our data demonstrate a delay in myelin formation in ASA,/, mice. This raises the possibility that similar alterations in MLD patients may contribute to the pathology of the disease. [source] Identification of Tmem10/Opalin as an oligodendrocyte enriched gene using expression profiling combined with genetic cell ablationGLIA, Issue 11 2008Neev Golan Abstract Oligodendrocytes form an insulating multilamellar structure of compact myelin around axons, which allows efficient and rapid propagation of action potentials. However, little is known about the molecular mechanisms operating at the onset of myelination and during maintenance of the myelin sheath in the adult. Here we use a genetic cell ablation approach combined with Affymetrix GeneChip microarrays to identify a number of oligodendrocyte-enriched genes that may play a key role in myelination. One of the "oligogenes" we cloned using this approach is Tmem10/Opalin, which encodes for a novel transmembrane glycoprotein. In situ hybridization and RT-PCR analysis revealed that Tmem10 is selectively expressed by oligodendrocytes and that its expression is induced during their differentiation. Developmental immunofluorescence analysis demonstrated that Tmem10 starts to be expressed in the white matter tracks of the cerebellum and the corpus callosum at the onset of myelination after the appearance of other myelin genes such as MBP. In contrast to the spinal cord and brain, Tmem10 was not detected in myelinating Schwann cells, indicating that it is a CNS-specific myelin protein. In mature oligodendrocytes, Tmem10 was present at the cell soma and processes, as well as along myelinated internodes, where it was occasionally concentrated at the paranodes. In myelinating spinal cord cultures, Tmem10 was detected in MBP-positive cellular processes that were aligned with underlying axons before myelination commenced. These results suggest a possible role of Tmem10 in oligodendrocyte differentiation and CNS myelination. © 2008 Wiley-Liss, Inc. [source] p38 mitogen-activated protein kinase is required for central nervous system myelinationGLIA, Issue 15 2007Gabriela Fragoso Abstract The p38 MAPKs are a family of kinases that regulate a number of cellular functions including cell migration, proliferation, and differentiation. Here, we report that p38 regulates oligodendrocyte differentiation. Inhibition of p38 with PD169316 and SB203580 prevented accumulation of protein and mRNA of cell-stage specific markers characteristic of differentiated oligodendrocytes, including myelin basic protein, myelin-associated glycoprotein, and the glycosphingolipids, galactosylceramide and sulfatide. In addition, the cell cycle regulator p27kip1 and the transcription factor Sox10 were also significantly reduced. Most significantly, p38 inhibitors completely and irreversibly blocked myelination of dorsal root ganglion neurons by oligodendrocytes and prevented the axolemmal organization of the axo-glial adhesion molecule Caspr. Our results suggest a role(s) for this kinase in key regulatory steps in the maturation of OLGs and initiation of myelination. © 2007 Wiley-Liss, Inc. [source] Stage-specific gene expression in early differentiating oligodendrocytesGLIA, Issue 2 2002Francesca Blasi Abstract The screening of a differential library from precursor and differentiated oligodendrocytes, obtained through the representational difference analysis (RDA) technique, has generated a number of cDNA recombinants corresponding to mRNA coding for known and unknown proteins: (1) mRNA coding for proteins involved in protein synthesis, (2) mRNA coding for proteins involved in the organization of the cytoskeleton, and (3) mRNA coding for proteins of unknown function. The expression profile of the mRNA was studied by Northern blot hybridization to the poly-A+ mRNA from primary rat progenitor and differentiated oligodendrocytes. In most cases, hybridization to the precursor was higher than hybridization to the differentiated mRNA, supporting the validity of the differential screening. Hybridization of the cDNA to rat cerebral hemisphere and brain stem poly-A+ mRNA, isolated from 1- to 90-day-old rats, confirms the results obtained with the mRNA from differentiating oligodendrocytes. The intensity of the hybridization bands decreases as differentiation proceeds. The pattern of expression observed in oligodendrocytes is different from that found in the brain only in the case of the nexin-1 mRNA, the level of which remains essentially constant throughout differentiation both in the brain stem and in the cerebral hemispheres, in agreement with the published data. In contrast, the intensity of hybridization to the oligodendrocyte mRNA is dramatically lower in the differentiated cells compared with the progenitor oligodendrocyte cells. Some of the recombinant cDNA represent mRNA sequences present at high frequency distribution in the cells, while others belong to the rare sequences group. Six recombinants code for proteins of the ribosomal family, suggesting that of approximately 70 known ribosomal proteins, only a few are upregulated during oligodendrocyte differentiation. The third category of open reading frame (ORF) is represented by rare messengers coding for proteins of unknown functions and includes six clones: RDA 279, 11, 95, 96, 254, and 288. GLIA 39:114,123, 2002. © 2002 Wiley-Liss, Inc. [source] Agonists specific for the transcription factor PPARdelta accelerate differentiation of oligodendrocytesJOURNAL OF NEUROCHEMISTRY, Issue 2002R. P. Skoff Peroxisome proliferator activated receptors (PPARs) are transcription factors belonging to the nuclear hormone receptor superfamily that regulate key genes involved in lipid metabolism. PPAR, is ubiquitously expressed at low levels in many tissues and its function has remained elusive. However, we have shown that PPAR, is abundantly expressed in oligodendrocytes (Ols), suggesting this receptor plays a critical role in oligodendrocyte differentiation (Granneman et al. 1998 J. Neurosci. Res51, 563). We first investigated the effects of PPAR agonists on proliferation and differentiation of Ols in tissue culture. Primary glial and enriched Ol cultures were treated with ligands that specifically activate PPAR, and PPAR, (Berger et al. 1999 J. Biol. Chem. 274, 6717). PPAR, but not PPAR, agonists increased the size of OL membrane sheets within 24 h of application. The increase in membrane sheet size was mirrored by increases in MBP and PLP mRNA's. In enriched Ol cultures, the number of Ols was increased 70% with the PPAR, agonist but not the PPAR, agonist (Saluja et al. 2001 Glia33, 191). In vivo injections of PPAR, agonist into P2 and P3 mice show an increase of total macroglia in the ventral and dorsal funiculi of the spinal cord of 20,40% compared to controls. Preliminary observations suggest the Ols in agonist treated cultures are larger and more densely stained than controls. Our results show for the first time that a specific ligand for a transcription factor is capable of activating the program of Ol differentiation. Acknowledgements: Supported by NMSS. [source] Transgenic mice exhibiting oligodendrocyte-specific expression of a mutant protein tyrosine phosphatase epsilonJOURNAL OF NEUROCHEMISTRY, Issue 2002N. Muja Reversible tyrosine phosphorylation is integral to oligodendrocyte differentiation, and one participant of the phosphorylation cycle, PTP,, is induced in developing oligodendrocytes (Ranjan and Hudson, 1996). To define the role of PTP,, we generated mice expressing a catalytically inactive, hemagglutinin-epitope tagged PTP, (HA-PTP ,) from the 2,,3,-cyclic nucleotide 3,-phosphodiesterase (CNP) promoter. By competing with endogenous, normal PTP, for substrate binding, HA-PTP, would behave in a dominant negative fashion when overexpressed in these mice. Transgene mRNA peaks at postnatal day 21, coincident with the maximal expression of myelin protein mRNAs. Immunohistochemical analyses using antibodies against the HA epitope tag demonstrate that HA-PTP, is expressed in oligodendrocytes, but not in astrocytes and neurons. HA immunoreactivity was present in all myelinated brain structures including the corpus callosum, anterior commissure, and fornix, as well as in the subcortical, cerebellar, and spinal cord white matter. Gross differences in myelination or oligodendrocyte cell density in these brain regions were not detected using antibodies against CNP, myelin basic protein, and an oligodendrocyte marker, CC1. However, by EM axons of the optic nerve appear smaller and less extensively myelinated in transgenic mice than in wild-type littermates. Studies are underway to determine the functional effects of transgene expression on conduction velocity, on the profile of expressed genes, and on potential phosphorylated protein targets of PTP,. [source] Transcriptional Regulation of 2,,3,-Cyclic Nucleotide 3,-Phosphodiesterase Gene Expression by Cyclic AMP in C6 CellsJOURNAL OF NEUROCHEMISTRY, Issue 5 2000M. Gravel Abstract: It was recently shown that the two transcripts encoding the isoforms of 2,,3,-cyclic nucleotide 3,-phosphodiesterase (CNP1 and CNP2) are differentially regulated during the process of oligodendrocyte maturation. In oligodendrocyte precursors, only CNP2 mRNA is present, whereas in differentiating oligodendrocytes, both CNP1 and CNP2 mRNAs are expressed. This pattern of CNP expression is likely due to stage-specific transcriptional regulation of the two CNP promoters during the process of oligodendrocyte differentiation. Here, we report the influence of increased intracellular cyclic AMP (cAMP) levels on the transcription of both CNP1 and CNP2 mRNAs in rat C6 glioma cells. We found that the transcription of CNP1 mRNA was significantly increased in comparison with that of CNP2 mRNA in cells treated with cAMP analogues to elevate intracellular cAMP levels. This up-regulation of CNP1 expression (a) is due to an increase of transcription, (b) requires de novo protein synthesis, and (c) requires the activity of protein kinase A. These results are physiologically significant and support the idea that a cAMP-mediated pathway is part of the molecular mechanisms regulating the expression of CNP1 in oligodendrocytes. The regulation of CNP1 promoter activity by cAMP was then investigated in stably transfected C6 cell lines containing various deletions of the CNP promoter directing the bacterial chloramphenicol acetyltransferase gene. We showed that the sequence between nucleotides -126 and -102 was essential for the cAMP-dependent induction of CNP1 expression. Gel retardation analysis showed that two protein-DNA complexes are formed between this sequence and nuclear factors from C6 cells treated or not treated with cAMP. This suggests that the induction of CNP1 mRNA transcription is not mediated by changes in binding of nuclear factors that interact directly with the -126/-102 sequence. Sequence analysis of this region revealed the presence of a putative activator protein-2 (AP-2) binding site. It is interesting that mutagenesis of this region resulted in a significant reduction in transcriptional responses to cAMP, implying a possible role for the AP-2 factor in the expression of CNP1. In addition, we have shown that putative binding sites for activator protein-4 and nuclear factor-1 adjacent to the AP-2 site are required for efficient induction of CNP1 expression by cAMP. Taken together, our results show that the cAMP-dependent accumulation of CNP1 mRNA appears to depend on the synergistic interaction of several regulatory elements. [source] Chemical inducers and transcriptional markers of oligodendrocyte differentiationJOURNAL OF NEUROSCIENCE RESEARCH, Issue 12 2010Lara Joubert Abstract Oligodendrocytes generate and maintain myelin, which is essential for axonal function and protection of the mammalian central nervous system. To advance our molecular understanding of differentiation by these cells, we screened libraries of pharmacologically active compounds and identified inducers of differentiation of Oli-neu, a stable cell line of mouse oligodendrocyte precursors (OPCs). We identified four broad classes of inducers, namely, forskolin/cAMP (protein kinase A activators), steroids (glucocorticoids and retinoic acid), ErbB2 inhibitors, and nucleoside analogs, and confirmed the activity of these compounds on rat primary oligodendrocyte precursors and mixed cortical cultures. We also analyzed transcriptional responses in the chemically induced mouse and rat OPC differentiation processes and compared these with earlier studies. We confirm the view that ErbB2 is a natural signaling component that is required for OPC proliferation, whereas ErbB2 inhibition or genetic knockdown results in OPC differentiation. © 2010 Wiley-Liss, Inc. [source] Fibroblast growth factor-9 inhibits astrocyte differentiation of adult mouse neural progenitor cellsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 10 2009Maggie Lum Abstract Fibroblast growth factor-9 (FGF9) is expressed in the CNS and is reported to be a mitogen for glial cells, to promote neuronal survival, and to retard oligodendrocyte differentiation. Here we examined the effects of FGF9 on the differentiation, survival, and proliferation of adult neural progenitor cells derived from the adult mouse subventricular zone. FGF9 by itself induced neurosphere proliferation, but its effects were modest compared with those of epidermal growth factor and FGF2. When neurospheres were dissociated and plated for differentiation, FGF9 increased total cell number over time in a dose-dependent manner. Ki67 immunostaining and bromodeoxyuridine incorporation indicated that this was at least partially due to the continued presence of proliferative nestin-positive neural progenitor cells and ,III tubulin-positive neuronal precursors. FGF9 also promoted cell survival as indicated by a decreased number of TUNEL-positive cells over time. Assessment of differentiation showed that FGF9 increased neuron generation that reflected the increase in total cell number; however, the percentage of progenitor cells differentiating into neurons was slightly decreased. FGF9 had a modest effect on oligodendrocyte generation, although it appeared to slow the maturation of oligodenrocytes at higher concentrations. The most marked effect on differentiation was an almost total lack of glial fibrillary acidic protein (GFAP)-positive astrocytes up to 7 days following FGF9 addition, indicating that astrocyte differentiation was strongly inhibited. Total inhibition required prolonged treatment, although a 1-hr pulse was sufficient for partial inhibition, and bone morphogenic protein-4 could partially overcome the FGF9 inhibition of astrocyte differentiation. FGF9 therefore has multiple effects on adult neural precursor cell function, enhancing neuronal precursor proliferation and specifically inhibiting GFAP expression. © 2009 Wiley-Liss, Inc. [source] pH is an intracellular effector controlling differentiation of oligodendrocyte precursors in culture via activation of the ERK1/2 pathwayJOURNAL OF NEUROSCIENCE RESEARCH, Issue 7 2006Frédéric Bernard Abstract We reported previously that onset of oligodendrocyte precursor cell (OPC) differentiation is accompanied by an increase in intracellular pH (pHi). We show that OPC differentiation is dependent primarily on a permissive pHi value. The highest differentiation levels were observed for pHi values around 7.15 and inhibition of differentiation was observed at slightly more acidic or alkaline values. Clamping the pHi of OPCs at 7.15 caused a transient activation of ERK1/2 that was not observed at more acidic or alkaline values. Furthermore, inhibition of ERK activation with the UO126 compound totally prevented OPC differentiation in response to pHi shift. These results indicate that pHi, acting through the ERK1/2 pathway, is a key determinant for oligodendrocyte differentiation. We also show that this pHi pathway is involved in the process of retinoic acid-induced OPC differentiation. © 2006 Wiley-Liss, Inc. [source] Novel role for aspartoacylase in regulation of BDNF and timing of postnatal oligodendrogenesisJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2006Jeremy S. Francis Abstract Neuronal growth factors are thought to exert a significant degree of control over postnatal oligodendrogenesis, but mechanisms by which these factors coordinateoligodendrocyte development with the maturation of neural networks are poorly characterized. We present here a developmental analysis of aspartoacylase (Aspa)-null tremor rats and show a potential role for this hydrolytic enzyme in the regulation of a postnatal neurotrophic stimulus that impacts on early stages of oligodendrocyte differentiation. Abnormally high levels of brain-derived neurotrophic factor (BDNF) expression in the Aspa -null Tremor brain are associated with dysregulated oligodendrogenesis at a stage in development normally characterized by high levels of Aspa expression. BDNF promotes the survival of proliferating cells during the early stages of oligodendrocyte maturation in vitro, but seems to compromise the ability of these cells to populate the cortex in vivo. Aspartoacylase activity in oligodendrocytes is shown to provide for the negative regulation of BDNF in neurons, thereby determining the availability of a developmental stimulus via a mechanism that links oligodendroglial differentiation with neuronal maturation. © 2006 Wiley-Liss, Inc. [source] | ||||||||||