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Sun Y.,University of Veterinary Medicine Hannover | Sun Y.,Center for Systems Neuroscience Hanover | Lehmbecker A.,University of Veterinary Medicine Hannover | Lehmbecker A.,Center for Systems Neuroscience Hanover | And 11 more authors.
Neuropathology and Applied Neurobiology | Year: 2015

Aims: Insufficient oligodendroglial differentiation of oligodendroglial progenitor cells (OPCs) is suggested to be responsible for remyelination failure and astroglial scar formation in Theiler's murine encephalomyelitis (TME). The aim of the present study is to identify molecular key regulators of OPC differentiation in TME, and to dissect their mechanism of action in vitro. Methods: TME virus (TMEV) infected SJL/J-mice were evaluated by rotarod analysis, histopathology, immunohistology and gene expression microarray analysis. The STAT3 pathway was activated using meteorin and inhibited using STAT3 inhibitor VII in the glial progenitor cell line BO-1 and in primary rat OPCsin vitro. Results: As expected, immunohistology demonstrated progressively decreasing myelin basic protein-positive white matter in TME. In contrast, intralesional NG2-positive OPCs as well as GFAP-positive astrocytes were increased. Gene Set Enrichment Analysis revealed 26 Gene Ontology terms including 'JAK-STAT cascade' to be significantly positively correlated with the density of NG2-positive OPCs. Immunohistology revealed an increased amount of activated, phosphorylated STAT3-expressing astrocytes, OPCs, and microglia/macrophages within the lesions. Meteorin-induced activation of STAT3-signalling in BO-1 cells and primary rat OPCs resulted in an enhanced GFAP and reduced CNPase expression. In contrast, an oppositional result was observed in BO-1 cells treated with STAT3 inhibitor VII. Conclusions: The STAT3 pathway is a key regulator of OPC-differentiation, suggested to shift their differentiation from an oligodendroglial towards an astrocytic fate, thereby inducing astrogliosis and insufficient remyelination in TME. © 2014 British Neuropathological Society.


Podrygajlo G.,University of Veterinary Medicine Hannover | Podrygajlo G.,Center for Systems Neuroscience Hanover | Wiegreffe C.,Albert Ludwigs University of Freiburg | Wiegreffe C.,University of Ulm | And 3 more authors.
Developmental Dynamics | Year: 2010

Postmitotic neurons were generated from the human NT2 teratocarcinoma cell line in a novel cell aggregate differentiation procedure. Approximately a third of the differentiated neurons expressed cell markers related to cholinergic neurotransmission. To examine whether this human cell model system can be directed toward a motoneuronal fate, postmitotic neurons were co-cultured with mouse myotubes. Outgrowing neuronal processes established close contact with the myotubes and formed neuromuscular junction-like structures that bound α-bungarotoxin. To determine how grafted precursor cells and neurons respond to embryonic nerve tissue, NT2 cells at different stages of neural development were injected into chick embryo neural tube and brain. Grafted NT2 neurons populated both parts of the nervous system, sometimes migrating away from the site of injection. The neural tube appeared to be more permissive for neurite extensions than the brain. Moreover, extending neurites of spinal grafts were approaching the ventral roots, thus resembling motoneuronal projections. © 2009 Wiley-Liss, Inc.


Tegenge M.A.,University of Veterinary Medicine Hannover | Tegenge M.A.,Center for Systems Neuroscience Hanover | Tegenge M.A.,Johns Hopkins University | Bohnel H.,University of Gottingen | And 3 more authors.
Cellular and Molecular Neurobiology | Year: 2012

Botulinum neurotoxins (BoNTs) internalize into nerve terminals and block the release of neurotransmitters into the synapse. BoNTs are widely used as a therapeutic agent for treatment of movement disorders and recently gained more attention as a biological weapon. Consequently, there is strong interest to develop a cell-based assay platform to screen the toxicity and bioactivity of the BoNTs. In this study, we present an in vitro screening assay for BoNT/A based on differentiated human embryonal carcinoma stem (NT2) cells. The human NT2 cells fully differentiated into mature neurons that display immunoreactivity to cytoskeletal markers (βIII-tubulin and MAP2) and presynaptic proteins (synapsin and synaptotagmin I). We showed that the human NT2 cells undergo a process of exo-endocytotic synaptic vesicle recycling upon depolarization with high K + buffer. By employing an antibody directed against light chain of BoNT/A, we detected internalized toxin as a punctate staining along the neurites of the NT2 neurons. Using well-established methods of synaptic vesicle exocytosis assay (luminal synaptotagmin I and FM1-43 imaging) we show that preincubation with BoNT/A resulted in a blockade of vesicle release from human NT2 neurons in a dose-dependent manner. Moreover, this blocking effect of BoNT/A was abolished by pre-adsorbing the toxin with neutralizing antibody. In a proof of principle, we demonstrate that our cell culture assay for vesicle release is sensitive to BoNT/A and the activity of BoNT/A can be blocked by specific neutralizing antibodies. Overall our data suggest that human NT2 neurons are suitable for large scale screening of botulinum bioactivity. © Springer Science+Business Media, LLC 2012.


Hansmann F.,University of Veterinary Medicine Hannover | Hansmann F.,Center for Systems Neuroscience Hanover | Herder V.,University of Veterinary Medicine Hannover | Herder V.,Center for Systems Neuroscience Hanover | And 9 more authors.
Acta Neuropathologica | Year: 2012

Matrix metalloproteinases (MMPs) are a family of extracellular proteases involved in the pathogenesis of demyelinating diseases like multiple sclerosis (MS). The aim of the present study was to investigate whether MMPs induce direct myelin degradation, leukocyte infiltration, disruption of the blood-brain barrier (BBB), and/or extracellular matrix remodeling in the pathogenesis of Theiler's murine encephalomyelitis (TME), a virus-induced model of MS. During the demyelinating phase of TME, the highest transcriptional upregulation was detected for Mmp12, followed by Mmp3. Mmp12 -/- mice showed reduced demyelination, macrophage infiltration, and motor deficits compared with wild-type- and Mmp3 knock-out mice. However, BBB remained unaltered, and the amount of extracellular matrix deposition was similar in knock-out mice and wild-type mice. Furthermore, stereotaxic injection of activated MMP-3, -9, and -12 into the caudal cerebellar peduncle of adult mice induced a focally extensive primary demyelination prior to infiltration of inflammatory cells, as well as a reduction in the number of oligodendrocytes and a leakage of BBB. All these results demonstrate that MMP-12 plays an essential role in the pathogenesis of TME, most likely due to its primary myelin- or oligodendrocyte-toxic potential and its role in macrophage extravasation, whereas there was no sign of BBB damage or alterations to extracellular matrix remodeling/deposition. Thus, interrupting the MMP-12 cascade may be a relevant therapeutic approach for preventing chronic progressive demyelination. © 2012 Springer-Verlag.


Hansmann F.,University of Veterinary Medicine Hannover | Hansmann F.,Center for Systems Neuroscience Hanover | Herder V.,University of Veterinary Medicine Hannover | Herder V.,Center for Systems Neuroscience Hanover | And 3 more authors.
Journal of Comparative Pathology | Year: 2011

This report is the first description of a spinal epidermoid cyst (EC) in a SJL mouse and gives an overview on the occurrence of ECs in animals including dogs, horses, mice and rats. The EC was not detected grossly and the mouse did not display clinical signs or an altered rotarod performance. Microscopically, there was an oval cyst lined by stratified squamous epithelium that was attached to the dorsolateral meninges and caused moderate compression of the adjacent lumbar spinal cord. ECs in mice and rats are mainly located in the caudal part of the spinal cord with a variable, strain-dependent occurrence. ECs in mice and rats are not associated with clinical signs and can be interpreted as incidental findings. © 2011 Elsevier Ltd.


Scheiblich H.,University of Veterinary Medicine Hannover | Bicker G.,University of Veterinary Medicine Hannover | Bicker G.,Center for Systems Neuroscience Hanover
Developmental neurobiology | Year: 2015

Clearance of infected and apoptotic neuronal corpses during inflammatory conditions is a fundamental process to create a favorable environment for neuronal recovery. Microglia are the resident immune cells and the predominant phagocytic cells of the CNS, showing a multitude of cellular responses upon activation. Here, we investigated in functional assays how the CO generating enzyme heme oxygenase 1 (HO-1) influences BV-2 microglial migration, clearance of debris, and neurite outgrowth of human NT2 neurons. Stimulation of HO-1 activity attenuated microglial migration in a scratch wound assay, and phagocytosis in a cell culture model of acute inflammation comprising lipopolysaccharide (LPS)-activated microglia and apoptosis-induced neurons. Application of a CO donor prevented the production of NO during LPS stimulation, and reduced microglial migration and engulfment of neuronal debris. LPS-activated microglia inhibited neurite elongation of human neurons without requiring direct cell-cell surface contact. The inhibition of neurite outgrowth was totally reversed by application of exogenous CO or increased internal CO production through supply of the substrate hemin to HO. Our results point towards a vital cytoprotective role of HO-1/CO signaling after microglial activation. In addition, they support a therapeutic potential of CO releasing chemical agents in the treatment of excessive inflammatory conditions in the CNS. © 2014 Wiley Periodicals, Inc.


Krocher T.,Hannover Medical School | Krocher T.,Center for Systems Neuroscience Hanover | Malinovskaja K.,University of Tartu | Jurgenson M.,University of Tartu | And 11 more authors.
Brain Structure and Function | Year: 2013

Posttranslational modification of the neural cell adhesion molecule (NCAM) by polysialic acid (polySia) is crucial for nervous system development and brain plasticity. PolySia attachment is catalyzed by the polysialyltransferases (polySTs) ST8SIA2 and ST8SIA4, two enzymes with distinct but also common functions during neurodevelopment and in the adult brain. A growing body of evidence links aberrant levels of NCAM and polySia as well as variation in the ST8SIA2 gene to neuropsychiatric disorders, including schizophrenia. To investigate whether polyST deficiency might cause a schizophrenia-like phenotype, St8sia2−/− mice, St8sia4−/− mice and their wildtype littermates were assessed neuroanatomically and subjected to tests of cognition and sensorimotor functions. St8sia2−/− but not St8sia4−/− mice displayed enlarged lateral ventricles and a size reduction of the thalamus accompanied by a smaller internal capsule and a highly disorganized pattern of fibers connecting thalamus and cortex. Reduced levels of the vesicular glutamate transporter VGLUT2 pointed towards compromised glutamatergic thalamocortical input into the frontal cortex of St8sia2−/− mice. Both polyST-deficient lines were impaired in short- and long-term recognition memory, but only St8sia2−/− mice displayed impaired working memory and deficits in prepulse inhibition. Furthermore, only the St8sia2−/− mice exhibited anhedonic behavior and increased sensitivity to amphetamine-induced hyperlocomotion. These results reveal that reduced polysialylation in St8sia2−/− mice leads to pathological brain development and schizophrenia-like behavior. We therefore propose that genetic variation in ST8SIA2 has the potential to confer a neurodevelopmental predisposition to schizophrenia. © 2013, Springer-Verlag Berlin Heidelberg.


Nolle A.,Hannover Medical School | Nolle A.,Center for Systems Neuroscience Hanover | Zeug A.,Hannover Medical School | Van bergeijk J.,Hannover Medical School | And 21 more authors.
Human Molecular Genetics | Year: 2011

Spinal muscular atrophy (SMA), a frequent neurodegenerative disease, is caused by reduced levels of functional survival of motoneuron (SMN) protein. SMN is involved in multiple pathways, including RNA metabolism and splicing as well as motoneuron development and function. Here we provide evidence for a major contribution of the Rho-kinase (ROCK) pathway in SMA pathogenesis. Using an in vivo protein interaction system based on SUMOylation of proteins, we found that SMN is directly interacting with profilin2a. Profilin2a binds to a stretch of proline residues in SMN, which is heavily impaired by a novel SMN2 missense mutation (S230L) derived from a SMA patient. In different SMA models, we identified differential phosphorylation of the ROCK-downstream targets cofilin, myosin-light chain phosphatase and profilin2a. We suggest that hyper-phosphorylation of profilin2a is the molecular link between SMN and the ROCK pathway repressing neurite outgrowth in neuronal cells. Finally, we found a neuron-specific increase in the F-/G-actin ratio that further support the role of actin dynamics in SMA pathogenesis. © The Author 2011. Published by Oxford University Press. All rights reserved.


Begandt D.,Leibniz University of Hanover | Bader A.,Leibniz University of Hanover | Dreyer L.,Leibniz University of Hanover | Eisert N.,Leibniz University of Hanover | And 3 more authors.
Journal of Cell Communication and Signaling | Year: 2013

The rat aortic smooth muscle cell line A-10 was used to investigate the effect of dipyridamole on the gap junction coupling of smooth muscle cells. The scrape loading/dye transfer (SL/DT) technique revealed that dipyridamole concentrations between 5 μM and 100 μM significantly increased gap junction coupling. The adenosine receptor antagonist MRS 1754, as well as the PKA inhibitors Rp-cAMPS and H-89 were able to inhibit the dipyridamole-related increase in coupling, while forskolin and Br-cAMP also induced an enhancement of the gap junction coupling. Regarding the time-dependent behaviour of dipyridamole, a short-term effect characterised by an oscillatory reaction was observed for application times of less than 5 h, while applications times of at least 6 h resulted in a long-term effect, characterised by a constant increase of gap junction coupling to its maximum levels. This increase was not altered by prolonged presence of dipyridamole. In parallel, a short application of dipyridamole for at least 15 min was found to be sufficient to evoke the long-term effect measured 6 h after drug washout. We propose that in both the short-term and long-term effect, cAMP-related pathways are activated. The short-term phase could be related to an oscillatory cAMP effect, which might directly affect connexin trafficking, assembly and/or gap junction gating. The long-term effect is most likely related to the new expression and synthesis of connexins. With previous data from a bovine aortic endothelial cell line, the present results show that gap junction coupling of vascular cells is a target for dipyridamole. © 2013 The International CCN Society.


Muhlenhoff M.,Hannover Medical School | Rollenhagen M.,Hannover Medical School | Rollenhagen M.,University of Dundee | Werneburg S.,Hannover Medical School | And 5 more authors.
Neurochemical Research | Year: 2013

The glycan polysialic acid is well-known as a unique posttranslational modification of the neural cell adhesion molecule NCAM. Despite remarkable acceptor specificity, however, a few other proteins can be targets of polysialylation. Here, we recapitulate the biosynthesis of polysialic acid by the two polysialyltransferases ST8SIA2 and ST8SIA4 and highlight the increasing evidence that variation in the human ST8SIA2 gene is linked to schizophrenia and possibly other neuropsychiatric disorders. Moreover, we summarize the knowledge on the role of NCAM polysialylation in brain development gained by the analysis of NCAM- and polysialyltransferase-deficient mouse models. The last part of this review is focused on recent advances in identifying SynCAM 1 and neuropilin-2 as novel acceptors of polysialic acid in NG2 cells of the perinatal brain and in dendritic cells of the immune system, respectively. © 2013 Springer Science+Business Media New York.

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