Melitta Schachner

Publications (244)1348.81 Total impact

• Article: Adhesion molecule L1 binds to amyloid beta and reduces Alzheimer's disease pathology in mice.

  Nevena Djogo, Igor Jakovcevski, Christian Müller, Hyun Joon Lee, Jin-Chong Xu, Mira Jakovcevski, Sebastian Kügler, Gabriele Loers, Melitta Schachner
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  ABSTRACT: Alzheimer's disease (AD) is a devastating neurodegenerative disorder and the most common cause of elderly dementia. In an effort to contribute to the potential of molecular approaches to reduce degenerative processes we have tested the possibility that the neural adhesion molecule L1 ameliorates some characteristic cellular and molecular parameters associated with the disease in a mouse model of AD. Three-month-old mice overexpressing mutated forms of amyloid precursor protein and presenilin-1 under the control of a neuron-specific promoter received an injection of adeno-associated virus encoding the neuronal isoform of full-length L1 (AAV-L1) or, as negative control, green fluorescent protein (AAV-GFP) into the hippocampus and occipital cortex. Four months after virus injection, the mice were analyzed for histological and biochemical parameters of AD. AAV-L1 injection decreased the Aβ plaque load, levels of Aβ42, Aβ42/40 ratio and astrogliosis compared with AAV-GFP controls. AAV-L1 injected mice also had increased densities of inhibitory synaptic terminals on pyramidal cells in the hippocampus when compared with AAV-GFP controls. Numbers of microglial cells/macrophages were similar in both groups, but numbers of microglial cells/macrophages per plaque were increased in AAV-L1 injected mice. To probe for a molecular mechanism that may underlie these effects, we analyzed whether L1 would directly and specifically interact with Aβ. In a label-free binding assay, concentration dependent binding of the extracellular domain of L1, but not of the close homolog of L1 to Aβ40 and Aβ42 was seen, with the fibronectin type III homologous repeats 1-3 of L1 mediating this effect. Aggregation of Aβ42 in vitro was reduced in the presence of the extracellular domain of L1. The combined observations indicate that L1, when overexpressed in neurons and glia, reduces several histopathological hallmarks of AD in mice, possibly by reduction of Aβ aggregation. L1 thus appears to be a candidate molecule to ameliorate the pathology of AD, when applied in therapeutically viable and non-viral treatment schemes.
  Neurobiology of Disease 04/2013; · 5.40 Impact Factor
• Article: Syntenin-a promotes spinal cord regeneration following injury in adult zebrafish.

  Yong Yu, Melitta Schachner
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  ABSTRACT: In contrast to mammals, adult zebrafish recover locomotor function after spinal cord injury, in part due to the capacity of the central nervous system to repair severed connections. To identify molecular cues that underlie regeneration, we conducted mRNA expression profiling and found that syntenin-a expression is upregulated in the adult zebrafish spinal cord caudal to the lesion site after injury. Syntenin is a scaffolding protein involved in mammalian cell adhesion and movement, axonal outgrowth, establishment of cell polarity, and protein trafficking. It could thus be expected to be involved in supporting regeneration in fish. Syntenin-a mRNA and protein are expressed in neurons, glia and newly generated neural cells, and upregulated caudal to the lesion site on days 6 and 11 following spinal cord injury. Treatment of spinal cord-injured fish with two different antisense morpholinos to knock down syntenin-a expression resulted in significant inhibition of locomotor recovery at 5 and 6 weeks after injury, when compared to control morpholino-treated fish. Knock-down of syntenin-a reduced regrowth of descending axons from brainstem neurons into the spinal cord caudal to the lesion site. These observations indicate that syntenin-a is involved in regeneration after traumatic insult to the central nervous system of adult zebrafish, potentially leading to novel insights into the cellular and molecular mechanisms that require activation in the regeneration-deficient mammalian central nervous system.
  European Journal of Neuroscience 04/2013; · 3.63 Impact Factor
• Source

  Available from: Nikolay E Nifantiev

  Dataset: ja2083015 si 001

  Alexander O Chizhov, Gabriele Loers, Ana Ardá, Melitta Schachner, Jesús Jiménez-Barbero, Yury E Tsvetkov, Elena V Sukhova, Elena A Khatuntseva, Nikolay E Nifantiev, Monika Burg-Roderfeld, Hans-Christian Siebert, Alexey A Grachev
• Source

  Available from: Nikolay E Nifantiev

  Dataset: ja2083015 si 002

  Alexander O Chizhov, Gabriele Loers, Ana Ardá, Melitta Schachner, Jesús Jiménez-Barbero, Yury E Tsvetkov, Elena V Sukhova, Elena A Khatuntseva, Nikolay E Nifantiev, Monika Burg-Roderfeld, Hans-Christian Siebert, Alexey A Grachev
• Source

  Available from: Weijiang Zhao

  Article: Neuregulin 1 enhances cell adhesion molecule l1 expression in human glioma cells and promotes their migration as a function of malignancy.

  Wei-Jiang Zhao, Melitta Schachner
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  ABSTRACT: Similar functions of L1, a cell adhesion molecule, and the cytokine neuregulin 1 (Nrg1) have been suggested in tumorigenesis and the promotion of metastasis. We studied the relationships of Nrg1 and L1 expression in human gliomas. Using immunofluorescence staining on a human glioma tissue microarray, we found a positive correlation between levels of L1 and Nrg1α or Nrg1β expression; expression tended to increase with increasing WHO (World Health Organization) tumor grade. L1 was also found to colocalize with either Nrg1 isoform. In cultures of U87-MG human glioblastoma and human U251 and SHG-44 glioma cells, the base levels of full-length L1 expression were increased by the 2 Nrg1 molecules in the nanomolar range, and Nrg1 siRNA downregulated full-length L1 expression in these tumor cell lines. U87-MG cells treated with either Nrg1 isoform also showed enhanced migration when compared with that treated with vehicle control. In addition, administration of either lapatinib (a dual inhibitor of both the epidermal growth factor receptor and ErbB-2) or erlotinib (an inhibitor of the epidermal growth factor receptor) in combination with either Nrg1α or Nrg1β inhibited the L1 expression elicited by these cytokines in U87-MG cells. Together, our data suggest that Nrg1 regulates L1 expression in gliomas, and that Nrg1 may contribute to malignancy by upregulating the L1 expression in glioblastoma cells, thereby enhancing their migration.
  Journal of neuropathology and experimental neurology. 03/2013; 72(3):244-55.
• Source

  Available from: Bibhudatta Mishra

  Article: Dermatan 4-O-sulfotransferase1 ablation accelerates peripheral nerve regeneration.

  Nuray Akyüz, Sandra Rost, Ali Mehanna, Shan Bian, Gabriele Loers, Iris Oezen, Bibhudatta Mishra, Kathrin Hoffmann, Daria Guseva, Ewa Laczynska, Andrey Irintchev, Igor Jakovcevski, Melitta Schachner
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  ABSTRACT: Chondroitin sulfate (CS) and dermatan sulfate (DS) proteoglycans are major components of the extracellular matrix implicated in neural development, plasticity and regeneration. While it is accepted that CS are major inhibitors of neural regeneration, the contributions of DS to regeneration have not been assessed. To enable a novel approach in studies on DS versus CS roles during development and regeneration, we generated a mouse deficient in the dermatan 4-O-sulfotransferase1 (Chst14(-/-)), a key enzyme in the synthesis of iduronic acid-containing modules found in DS but not CS. In wild-type mice, Chst14 is expressed at high levels in the skin and in the nervous system, and is enriched in astrocytes and Schwann cells. Ablation of Chst14, and the assumed failure to produce DS, resulted in smaller body mass, reduced fertility, kinked tail and increased skin fragility compared with wild-type (Chst14(+/+)) littermates, but brain weight and gross anatomy were unaffected. Neurons and Schwann cells from Chst14(-/-) mice formed longer processes in vitro, and Chst14(-/-) Schwann cells proliferated more than Chst14(+/+) Schwann cells. After femoral nerve transection/suture, functional recovery and axonal regrowth in Chst14(-/-) mice were initially accelerated but the final outcome 3 months after injury was not better than that in Chst14(+/+) littermates. These results suggest that while Chst14 and its enzymatic products might be of limited importance for neural development, they may contribute to the regeneration-restricting environment in the adult mammalian nervous system.
  Experimental Neurology 01/2013; · 4.70 Impact Factor
• Source

  Available from: Bibhudatta Mishra

  Article: Functional role of the interaction between polysialic acid and Myristoylated Alanine Rich C Kinase Substrate at the plasma membrane.

  Thomas Theis, Bibhudatta Mishra, Maren von der Ohe, Gabriele Loers, Maksymilian Prondzynski, Ole Pless, Perry J Blackshear, Melitta Schachner, Ralf Kleene
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  ABSTRACT: Polysialic acid (PSA) is a homopolymeric glycan that plays crucial roles in the developing and adult nervous system. So far, only a few PSA-binding proteins have been identified. Here, we identify Myristoylated Alanine Rich C Kinase Substrate (MARCKS) as novel PSA binding partner. Binding assays showed a direct interaction between PSA and a peptide comprising the effector domain of MARCKS (MARCKS-ED). Co-immunoprecipitation of PSA-carrying neural cell adhesion molecule (PSA-NCAM) with MARCKS and co-immunostaining of MARCKS and PSA at the cell membrane of hippocampal neurons confirm the interaction between PSA and MARCKS. Co-localization and an intimate interaction of PSA and MARCKS at the cell surface was seen by confocal microscopy and Fluorescence Resonance Energy Transfer (FRET) analysis after addition of fluorescently labeled PSA or PSA-NCAM to live CHO cells or hippocampal neurons expressing MARCKS as fusion protein with green fluorescent protein (GFP). Cross-linking experiments showed that extracellularly applied PSA or PSA-NCAM and intracellularly expressed MARCKS-GFP are in close contact, suggesting that PSA and MARCKS interact with each other at the plasma membrane from opposite sides. Insertion of PSA and MARCKS-ED peptide into lipid bilayers from opposite sides alters the electric properties of the bilayer confirming the notion that PSA and the effector domain of MARCKS interact at and/or within the plane of the membrane. The MARCKS-ED peptide abolished PSA-induced enhancement of neurite outgrowth from cultured hippocampal neurons indicating an important functional role for the interaction between MARCKS and PSA in the developing and adult nervous system.
  Journal of Biological Chemistry 01/2013; · 4.77 Impact Factor
• Article: The Neural Cell Adhesion Molecule (NCAM) Associates with and Signals through p21-Activated Kinase 1 (Pak1).

  Shen Li, Iryna Leshchyns'ka, Yana Chernyshova, Melitta Schachner, Vladimir Sytnyk
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  ABSTRACT: The Neural cell adhesion molecule (NCAM) plays an important role in regulation of nervous system development. To expand our understanding of the molecular mechanisms via which NCAM influences differentiation of neurons, we used a yeast two-hybrid screening to search for new binding partners of NCAM and identified p21-activated kinase 1 (Pak1). We show that NCAM interacts with Pak1 in growth cones of neurons. The autophosphorylation and activity of Pak1 were enhanced when isolated growth cones were incubated with NCAM function triggering antibodies, which mimic the interaction between NCAM and its extracellular ligands. The association of Pak1 with cell membranes, the efficiency of Pak1 binding to its activators, and Pak1 activity were inhibited in brains of NCAM-deficient mice. NCAM-dependent Pak1 activation was abolished after lipid raft disruption, suggesting that NCAM promotes Pak1 activation in the lipid raft environment. Phosphorylation of the downstream Pak1 effectors LIMK1 and cofilin was reduced in growth cones from NCAM-deficient neurons, which was accompanied by decreased levels of filamentous actin and inhibited filopodium mobility in the growth cones. Dominant-negative Pak1 inhibited and constitutively active Pak1 enhanced the ability of neurons to increase neurite outgrowth in response to the extracellular ligands of NCAM. Our combined observations thus indicate that NCAM activates Pak1 to drive actin polymerization to promote neuronal differentiation.
  Journal of Neuroscience 01/2013; 33(2):790-803. · 7.11 Impact Factor
• Article: Generation of Amyloid-β Is Reduced by the Interaction of Calreticulin with Amyloid Precursor Protein, Presenilin and Nicastrin.

  Nina Stemmer, Elena Strekalova, Nevena Djogo, Frank Plöger, Gabriele Loers, David Lutz, Friedrich Buck, Marek Michalak, Melitta Schachner, Ralf Kleene
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  ABSTRACT: Dysregulation of the proteolytic processing of amyloid precursor protein by γ-secretase and the ensuing generation of amyloid-β is associated with the pathogenesis of Alzheimer's disease. Thus, the identification of amyloid precursor protein binding proteins involved in regulating processing of amyloid precursor protein by the γ-secretase complex is essential for understanding the mechanisms underlying the molecular pathology of the disease. We identified calreticulin as novel amyloid precursor protein interaction partner that binds to the γ-secretase cleavage site within amyloid precursor protein and showed that this Ca(2+)- and N-glycan-independent interaction is mediated by amino acids 330-344 in the C-terminal C-domain of calreticulin. Co-immunoprecipitation confirmed that calreticulin is not only associated with amyloid precursor protein but also with the γ-secretase complex members presenilin and nicastrin. Calreticulin was detected at the cell surface by surface biotinylation of cells overexpressing amyloid precursor protein and was co-localized by immunostaining with amyloid precursor protein and presenilin at the cell surface of hippocampal neurons. The P-domain of calreticulin located between the N-terminal N-domain and the C-domain interacts with presenilin, the catalytic subunit of the γ-secretase complex. The P- and C-domains also interact with nicastrin, another functionally important subunit of this complex. Transfection of amyloid precursor protein overexpressing cells with full-length calreticulin leads to a decrease in amyloid-β42 levels in culture supernatants, while transfection with the P-domain increases amyloid-β40 levels. Similarly, application of the recombinant P- or C-domains and of a synthetic calreticulin peptide comprising amino acid 330-344 to amyloid precursor protein overexpressing cells result in elevated amyloid-β40 and amyloid-β42 levels, respectively. These findings indicate that the interaction of calreticulin with amyloid precursor protein and the γ-secretase complex regulates the proteolytic processing of amyloid precursor protein by the γ-secretase complex, pointing to calreticulin as a potential target for therapy in Alzheimer's disease.
  PLoS ONE 01/2013; 8(4):e61299. · 4.09 Impact Factor
• Article: Tenascins and inflammation in disorders of the nervous system.

  Igor Jakovcevski, Djordje Miljkovic, Melitta Schachner, Pavle R Andjus
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  ABSTRACT: In vitro and in vivo studies on the role of tenascins have shown that the two paradigmatic glycoproteins of the tenascin family, tenascin-C (TnC) and tenascin-R (TnR) play important roles in cell proliferation and migration, fate determination, axonal pathfinding, myelination, and synaptic plasticity. As components of the extracellular matrix, both molecules show distinct, but also overlapping dual functions in inhibiting and promoting cell interactions depending on the cell type, developmental stage and molecular microenvironment. They are expressed by neurons and glia as well as, for TnC, by cells of the immune system. The functional relationship between neural and immune cells becomes relevant in acute and chronic nervous system disorders, in particular when the blood brain and blood peripheral nerve barriers are compromised. In this review, we will describe the functional parameters of the two molecules in cell interactions during development and, in the adult, in synaptic activity and plasticity, as well as regeneration after injury, with TnC being conducive for regeneration and TnR being inhibitory for functional recovery. Although not much is known about the role of tenascins in neuroinflammation, we will describe emerging knowledge on the interplay between neural and immune cells in autoimmune diseases, such as multiple sclerosis and polyneuropathies. We will attempt to point out the directions of experimental approaches that we envisage would help gaining insights into the complex interplay of TnC and TnR with the cells that express them in pathological conditions of nervous and immune systems.
  Amino Acids 12/2012; · 3.25 Impact Factor
• Article: Heterozygosity for the mutated X-chromosome-linked L1 cell adhesion molecule gene leads to increased numbers of neurons and enhanced metabolism in the forebrain of female carrier mice.

  Janinne Sylvie Schmid, Christian Bernreuther, Alexander G Nikonenko, Zhang Ling, Günter Mies, Konstantin-A Hossmann, Igor Jakovcevski, Melitta Schachner
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  ABSTRACT: Mutations in the X-chromosomal L1CAM gene lead to severe neurological deficits. In this study, we analyzed brains of female mice heterozygous for L1 (L1+/-) to gain insights into the brain structure of human females carrying one mutated L1 allele. From postnatal day 7 onward into adulthood, L1+/- female mice show an increased density of neurons in the neocortex and basal ganglia in comparison to wild-type (L1+/+) mice, correlating with enhanced metabolic parameters as measured in vivo. The densities of astrocytes and parvalbumin immunoreactive interneurons were not altered. No significant differences between L1+/- and L1+/+ mice were seen for cell proliferation in the cortex during embryonic days 11.5-15.5. Neuronal differentiation as estimated by analysis of doublecortin-immunoreactive cortical cells of embryonic brains was similar in L1+/- and L1+/+ mice. Interestingly, at postnatal days 3 and 5, apoptosis was reduced in L1+/- compared to L1+/+ mice. We suggest that reduced apoptosis leads to increased neuronal density in adult L1+/- mice. In conclusion, L1+/- mice display an unexpected phenotype that is not an intermediate between L1+/+ mice and mice deficient in L1 (L1-/y), but a novel phenotype which is challenging to understand regarding its underlying molecular and cellular mechanisms.
  Brain Structure and Function 11/2012; · 5.63 Impact Factor
• Article: Lipid raft-dependent endocytosis of close homologue of adhesion molecule L1 (CHL1) promotes neuritogenesis.

  Nan Tian, Iryna Leshchyns'ka, Jeffrey H Welch, Witold Diakowski, Hongyuan Yang, Melitta Schachner, Vladimir Sytnyk
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  ABSTRACT: CHL1 plays a dual role by either promoting or inhibiting neuritogenesis. We here report that neuritogenesis promoting ligand-dependent cell surface clustering of CHL1 induces palmitoylation and lipid raft-dependent endocytosis of CHL1. We identify βII spectrin as a binding partner of CHL1, and show that partial disruption of the complex between CHL1 and βII spectrin accompanies CHL1 endocytosis. Inhibition of the association of CHL1 with lipid rafts by pharmacological disruption of lipid rafts or by mutation of cysteine 1102 within the intracellular domain of CHL1 reduces endocytosis of CHL1. Endocytosis of CHL1 is also reduced by nifedipine, an inhibitor of L-type voltage-dependent Ca2+ channels. CHL1-dependent neurite outgrowth is reduced by inhibitors of lipid raft assembly, inhibitors of voltage-dependent Ca2+ channels and overexpression of CHL1 with mutated cysteine C1102. Our results suggest that ligand-induced and lipid raft-dependent regulation of CHL1 adhesion via Ca2+-dependent remodeling of the CHL1/βII spectrin complex and CHL1 endocytosis are required for CHL1-dependent neurite outgrowth.
  Journal of Biological Chemistry 11/2012; · 4.77 Impact Factor
• Article: Major vault protein promotes locomotor recovery and regeneration after spinal cord injury in adult zebrafish.

  Hong-Chao Pan, Jin-Fei Lin, Li-Ping Ma, Yan-Qin Shen, Melitta Schachner
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  ABSTRACT: In contrast to mammals, adult zebrafish recover locomotor functions after spinal cord injury (SCI), in part due to axonal regrowth and regeneration permissivity of the central nervous system. Upregulation of major vault protein (MVP) expression after spinal cord injury in the brainstem of the adult zebrafish prompted us to probe for its contribution to recovery after SCI. MVP is a multifunctional protein expressed not only in many types of tumours but also in the nervous system, where its importance for regeneration is, however, unclear. Using an established zebrafish SCI model, we found that MVP mRNA and protein expression levels were increased in ependymal cells in the spinal cord caudal to the lesion site at 6 and 11 days after SCI. Double immunolabelling showed that MVP was co-localised with Islet-1 or tyrosine hydroxylase around the central canal of the spinal cord in sham-injured control fish and injured fish 11 days after surgery. MVP co-localised with the neural stem cell marker nestin in ependymal cells after injury. By using an in vivo morpholino-based knock-down approach, we found that the distance moved by MVP morpholino-treated fish was reduced at 4, 5 and 6 weeks after SCI when compared to fish treated with standard control morpholino. Knock-down of MVP resulted in reduced regrowth of axons from brainstem neurons into the spinal cord caudal to the lesion site. These results indicate that MVP supports locomotor recovery and axonal regrowth after SCI in adult zebrafish.
  European Journal of Neuroscience 10/2012; · 3.63 Impact Factor
• Article: A surgery protocol for adult zebrafish spinal cord injury.

  Ping Fang, Jin-Fei Lin, Hong-Chao Pan, Yan-Qin Shen, Melitta Schachner
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  ABSTRACT: Adult zebrafish has a remarkable capability to recover from spinal cord injury, providing an excellent model for studying neuroregeneration. Here we list equipment and reagents, and give a detailed protocol for complete transection of the adult zebrafish spinal cord. In this protocol, potential problems and their solutions are described so that the zebrafish spinal cord injury model can be more easily and reproducibly performed. In addition, two assessments are introduced to monitor the success of the surgery and functional recovery: one test to assess free swimming capability and the other test to assess extent of neuroregeneration by in vivo anterograde axonal tracing. In the swimming behavior test, successful complete spinal cord transection is monitored by the inability of zebrafish to swim freely for 1 week after spinal cord injury, followed by the gradual reacquisition of full locomotor ability within 6 weeks after injury. As a morphometric correlate, anterograde axonal tracing allows the investigator to monitor the ability of regenerated axons to cross the lesion site and increasingly extend into the gray and white matter with time after injury, confirming functional recovery. This zebrafish model provides a paradigm for recovery from spinal cord injury, enabling the identification of pathways and components of neuroregeneration.
  Journal of Genetics and Genomics 09/2012; 39(9):481-7. · 1.88 Impact Factor
• Article: Improved regeneration after spinal cord injury in mice lacking functional T- and B-lymphocytes.

  Bin Wu, Dragana Matic, Nevena Djogo, Emanuela Szpotowicz, Melitta Schachner, Igor Jakovcevski
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  ABSTRACT: It is widely accepted that the immune system plays important functional roles in regeneration after injury to the spinal cord. Immune response towards injury involves a complex interplay of immune system cells, such as neutrophils, macrophages and microglia, T- and B-lymphocytes. We investigated the influence of the lymphocyte component of the immune system on the locomotor outcome of severe spinal cord injury in a genetic mouse model of immune suppression. Transgenic mice lacking mature T- and B-lymphocytes due to the recombination activating gene 2 gene deletion (RAG2-/- mice) were subjected to severe compression of the lower thoracic spinal cord, with the wild-type mice of the same inbred background serving as controls. According to both the Basso Mouse Scale score and single frame motion analysis, the RAG2-/- mice showed improved recovery in comparison to control mice at six weeks after injury. Better locomotor function was associated with enhanced catecholaminergic and cholinergic reinnervation of the spinal cord caudal to injury and increased axonal regrowth/sprouting at the site of injury. Myelination of axons in the ventral column measured as g-ratio was more extensive in RAG2-/- than in control mice 6weeks after injury. Additionally, the number of microglia/macrophages was decreased in the lumbar spinal cord of RAG2-/- mice after injury, whereas the number of astrocytes was increased compared with controls. We conclude that T- and B-lymphocytes restrict functional recovery from spinal cord injury by increasing numbers of microglia/macrophages as well as decreasing axonal sprouting and myelination.
  Experimental Neurology 07/2012; 237(2):274-85. · 4.70 Impact Factor
• Article: HMGB1 in development and diseases of the central nervous system.

  Ping Fang, Melitta Schachner, Yan-Qin Shen
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  ABSTRACT: High mobility group box 1 (HMGB1) is widely expressed in cells of vertebrates in two forms: a nuclear "architectural" factor and a secreted inflammatory factor. During early brain development, HMGB1 displays a complex temporal and spatial distribution pattern in the central nervous system. It facilitates neurite outgrowth and cell migration critical for processes, such as forebrain development. During adulthood, HMGB1 serves to induce neuroinflammation after injury, such as lesions in the spinal cord and brain. Receptor for advanced glycation end products and Toll-like receptors signal transduction pathways mediate HMGB1-induced neuroinflammation and necrosis. Increased levels of endogenous HMGB1 have also been detected in neurodegenerative diseases. However, in Huntington's disease, HMGB1 has been reported to protect neurons through activation of apurinic/apyrimidinic endonuclease and 5'-flap endonuclease-1, whereas in other neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis, HMGB1 serves as a risk factor for memory impairment, chronic neurodegeneration, and progression of neuroinflammation. Thus, HMGB1 plays important and double-edged roles during neural development and neurodegeneration. The HMGB1-mediated pathological mechanisms have remained largely elusive. Knowledge of these mechanisms is likely to lead to therapeutic targets for neurological diseases.
  Molecular Neurobiology 05/2012; 45(3):499-506. · 5.74 Impact Factor
• Article: In vitro generation of three-dimensional substrate-adherent embryonic stem cell-derived neural aggregates for application in animal models of neurological disorders.

  Gunnar Hargus, Yi-Fang Cui, Marcel Dihné, Christian Bernreuther, Melitta Schachner
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  ABSTRACT: In vitro-differentiated embryonic stem (ES) cells comprise a useful source for cell replacement therapy, but the efficiency and safety of a translational approach are highly dependent on optimized protocols for directed differentiation of ES cells into the desired cell types in vitro. Furthermore, the transplantation of three-dimensional ES cell-derived structures instead of a single-cell suspension may improve graft survival and function by providing a beneficial microenvironment for implanted cells. To this end, we have developed a new method to efficiently differentiate mouse ES cells into neural aggregates that consist predominantly (>90%) of postmitotic neurons, neural progenitor cells, and radial glia-like cells. When transplanted into the excitotoxically lesioned striatum of adult mice, these substrate-adherent embryonic stem cell-derived neural aggregates (SENAs) showed significant advantages over transplanted single-cell suspensions of ES cell-derived neural cells, including improved survival of GABAergic neurons, increased cell migration, and significantly decreased risk of teratoma formation. Furthermore, SENAs mediated functional improvement after transplantation into animal models of Parkinson's disease and spinal cord injury. This unit describes in detail how SENAs are efficiently derived from mouse ES cells in vitro and how SENAs are isolated for transplantation. Furthermore, methods are presented for successful implantation of SENAs into animal models of Huntington's disease, Parkinson's disease, and spinal cord injury to study the effects of stem cell-derived neural aggregates in a disease context in vivo.
  Current protocols in stem cell biology 05/2012; Chapter 2:Unit 2D.11.
• Article: Delayed applications of L1 and chondroitinase ABC promote recovery after spinal cord injury.

  Hyun Joon Lee, Shan Bian, Igor Jakovcevski, Bin Wu, Andrey Irintchev, Melitta Schachner
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  ABSTRACT: The inhibitory environment of the injured spinal cord is an obstacle to functional recovery and axonal regeneration in adult mammals. We had previously shown that injection of adeno-associated virus (AAV) encoding the L1 cell adhesion molecule (AAV-L1) at the time of acute thoracic compression injury of adult mice promotes locomotor recovery, which is associated with ameliorated astrogliosis and improved axonal regeneration in the lumbar spinal cord. In the present study, we investigated whether delayed injection of AAV-L1, chondroitinase ABC (Chase), or the combination of the two agents into the mouse spinal cord 3 weeks after injury would also lead to improved recovery. The Basso Mouse Scale showed enhanced locomotor recovery 12 weeks after application of the agents in all treatment groups compared to the control group that was injected with AAV encoding green fluorescent protein (AAV-GFP). Investigation of hindlimb function using single-frame motion analysis revealed, however, that L1 overexpression, but not injection of Chase, improved voluntary movements without body weight support, whereas injection of Chase, but not L1 overexpression, enhanced body weight support during stepping. Mice with the combined application of AAV-L1 and Chase showed improvement in both parameters. Enhanced motor recovery after combined application correlated with increased densities of cholinergic and GABAergic terminals at motoneuronal cell bodies, and of lamina-specific glutamatergic sensory afferents 15 weeks after injury, indicating enhanced synaptic rearrangements in the lumbar spinal cord below the lesion site. These findings suggest that L1 overexpression combined with Chase application may contribute to the treatment of sub-chronic spinal cord injury.
  Journal of neurotrauma 04/2012; 29(10):1850-63. · 4.25 Impact Factor
• Article: L1CAM increases MAP2 expression via the MAPK pathway to promote neurite outgrowth.

  Gunnar Heiko Dirk Poplawski, Ann-Kathrin Tranziska, Iryna Leshchyns'ka, Ingo Dunya Meier, Thomas Streichert, Vladimir Sytnyk, Melitta Schachner
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  ABSTRACT: The neural cell adhesion molecule L1 (L1CAM) promotes neurite outgrowth via mechanisms that are not completely understood, but are known to involve the cytoskeleton. Here, we show that L1 binds directly to the microtubule associated protein 2c (MAP2c). This isoform of MAP2 is predominantly expressed in developing neurons. We found that the mRNA and protein levels of MAP2c, but not of MAP2a/b, are reduced in brains of young adult L1-deficient transgenic mice. We show via ELISA, that MAP2c, but not MAP2a/b, binds directly to the intracellular domain of L1. Remarkably, all these MAP2 isoforms co-immunoprecipitate with L1, suggesting that MAP2a/b associates with L1 via intermediate binding partners. The expression levels of MAP2a/b/c correlate with those of L1 in different brain regions of early postnatal mice, while expression levels of heat shock cognate protein 70 (Hsc70) or actin do not. L1 enhances the expression of MAP2a/b/c in cultured hippocampal neurons depending on activation of the mitogen-activated protein kinase (MAPK) pathway. Deficiency in both L1 and MAP2a/b/c expression results in reduced neurite outgrowth in vitro. We propose that the L1-triggered increase in MAP2a/b/c expression is required to promote neurite outgrowth.
  Molecular and Cellular Neuroscience 04/2012; 50(2):169-78. · 3.66 Impact Factor
• Article: Adhesion molecules close homolog of L1 and tenascin-C affect blood-spinal cord barrier repair.

  Nicole R Peter, Ronak T Shah, Jian Chen, Andrey Irintchev, Melitta Schachner
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  ABSTRACT: Mice deficient in the recognition molecules, close homolog of L1 (CHL1) and tenascin-C, show improved and reduced functional recovery, respectively, after spinal cord injury compared with wild-type littermates. In this study, we addressed the question whether the differential functional outcome was paralleled by differences in blood-spinal cord barrier (BSCB) repair in the two mouse strains. We conducted spinal cord compression injuries in knock-out and wild-type mice. BSCB permeability was assessed by measuring the Evans blue spread within the spinal cord tissue at 14-21 days after injury. Results show that CHL1 reduces and tenascin-C enhances BSCB permeability, suggesting a correlation between functional outcome and BSCB repair.
  Neuroreport 04/2012; 23(8):479-82. · 1.66 Impact Factor