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Spinal Cord White Matter (spinal + cord_white_matter)
Selected AbstractsMyelin transcription factor 1 (Myt1) expression in demyelinated lesions of rodent and human CNSGLIA, Issue 7 2007Adam C. Vana Abstract Myelin transcription factor 1 (Myt1) is a zinc-finger DNA binding protein that influences developing oligodendrocyte progenitor (OP) cell proliferation, differentiation, and myelin gene transcription in vitro. The potential of Myt1 to play a role in OP responses leading to remyelination was examined using murine hepatitis virus strain A59 (MHV) to induce spinal cord demyelination and potential relevance to human pathology was evaluated in multiple sclerosis (MS) lesions. In MHV-infected mice, the density of Myt1 expressing cells markedly increased in lesioned areas of spinal cord white matter. Myt1 expressing cells proliferated most extensively during active demyelination and subsequently accumulated to maximal levels during early remyelination. Cells with nuclear Myt1 immunoreactivity were mainly OP cells, identified by co-localization with platelet-derived growth factor alpha receptor, with additional phenotypes being either oligodendrocytes or neural stem cells, identified by CC1 antigen and Musashi1, respectively. The density of OP cells expressing Myt1 was significantly increased in white matter of MHV-infected mice during demyelination and early remyelination then as remyelination advanced the values returned to levels comparable to PBS-injected control mice. In MHV lesions, Myt1 was not expressed in astrocytes, lymphocytes, or macrophage/microglial cells. MS lesions demonstrated increased Myt1 expression in both the periplaque white matter adjacent to lesions and within early remyelinating lesions. These results suggesta potential role for Myt1 in the regeneration of oligodendrocyte lineage cells in response to demyelination. © 2007 Wiley-Liss, Inc. [source] Involvement of neuropsin in the pathogenesis of experimental autoimmune encephalomyelitisGLIA, Issue 2 2005Ryuji Terayama Abstract Inflammation, demyelination, and axonal damage of the central nervous system (CNS) are major pathological features of multiple sclerosis (MS). Proteolytic digestion of the blood-brain barrier and myelin protein by serine proteases is known to contribute to the development and progression of MS. Neuropsin, a serine protease, has a role in neuronal plasticity, and its expression has been shown to be upregulated in response to injury to the CNS. To determine the possible involvement of neuropsin in demyelinating diseases of the CNS, we examined its expression in myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), a recognized animal model for MS. Neuropsin mRNA expression was induced in the spinal cord white matter of mice with EAE. Combined in situ hybridization and immunohistochemistry demonstrated that most of the cells expressing neuropsin mRNA showed immunoreactivity for CNPase, a cell-specific marker for oligodendrocytes. Mice lacking neuropsin (neuropsin,/,) exhibited an altered EAE progression characterized by delayed onset and progression of clinical symptoms as compared to wild-type mice. Neuropsin,/, mice also showed attenuated demyelination and delayed oligodendroglial death early during the course of EAE. These observations suggest that neuropsin is involved in the pathogenesis of EAE mediated by demyelination and oligodendroglial death. © 2005 Wiley-Liss, Inc. [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] Complex interplay between glutamate receptors and intracellular Ca2+ stores during ischaemia in rat spinal cord white matterTHE JOURNAL OF PHYSIOLOGY, Issue 1 2006Mohamed Ouardouz Electrophysiological recordings of propagated compound action potentials (CAPs) and axonal Ca2+ measurements using confocal microscopy were used to study the interplay between AMPA receptors and intracellullar Ca2+ stores in rat spinal dorsal columns subjected to in vitro combined oxygen and glucose deprivation (OGD). Removal of Ca2+ or Na+ from the perfusate was protective after 30 but not 60 min of OGD. TTX was ineffective with either exposure, consistent with its modest effect on ischaemic depolarization. In contrast, AMPA antagonists were very protective, even after 60 min of OGD where 0Ca2++ EGTA perfusate was ineffective. Similarly, blocking ryanodine receptor-mediated Ca2+ mobilization from internal stores (0Ca2++ nimodipine or 0Ca2++ ryanodine), or inositol 1,4,5-trisphosphate (IP3)-dependent Ca2+ release (block of group 1 metabotropic glutamate receptors with 1-aminoindan-1,5-dicarboxylic acid, inhibition of phospholipase C with U73122 or IP3 receptor block with 2APB; each in 0Ca2+) were each very protective, with the combination resulting in virtually complete functional recovery after 1 h OGD (97 ± 32% CAP recovery versus 4 ± 6% in artificial cerebrospinal fluid). AMPA induced a rise in Ca2+ concentration in normoxic axons, which was greatly reduced by blocking ryanodine receptors. Our data therefore suggest a novel and surprisingly complex interplay between AMPA receptors and Ca2+ mobilization from intracellular Ca2+ stores. We propose that AMPA receptors may not only allow Ca2+ influx from the extracellular space, but may also significantly influence Ca2+ release from intra-axonal Ca2+ stores. In dorsal column axons, AMPA receptor-dependent mechanisms appear to exert a greater influence than voltage-gated Na+ channels on functional outcome following OGD. [source] CD40L is Critical for Protection from Demyelinating Disease and Development of Spontaneous Remyelination in a Mouse Model of Multiple SclerosisBRAIN PATHOLOGY, Issue 1 2000Kristen M. Drescher Theiler's murine encephalomyelitis virus (TMEV) induces acute neuronal disease followed by chronic demyelination in susceptible strains of mice. In this study we examined the role of a limited immune defect (deletion or blocking of CD40 ligand [CD40L]) on the extent of brain disease, susceptibility to demyelination, and the ability of demyelinated mice to spontaneously remyelinate following TMEV infection. We demonstrated that CD40L-dependent immune responses participate in pathogenesis in the cerebellum and the spinal cord white matter but protect the striatum of susceptible SJL/J mice. In mice on a background resistant to TMEV-induced demyelination (C57BL/6), the lack of CD40L resulted in increased striatal disease and meningeal inflammation. In addition, CD40L was required to maintain resistance to demyelination and clinical deficits in H-2b mice. CD40L-mediated interactions were also necessary for development of protective H-2b -restricted cytotoxic T cell responses directed against the VP2 region of TMEV as well as for spontaneous remyelination of the spinal cord white matter. The data presented here demonstrated the critical role of this molecule in both antibody- and cell-mediated protective immune responses in distinct phases of TMEV-mediated pathology. [source] | ||||||||||