The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
Peter Sonderegger - One of the best experts on this subject based on the ideXlab platform.
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Axonin 1 tag 1 mediates cell cell adhesion by a cis assisted trans interaction
Journal of Biological Chemistry, 2002Co-Authors: Beat Kunz, Christoph Rader, Urs Ziegler, Marianne Spirig, Ruth Lierheimer, Peter SondereggerAbstract:The neural cell adhesion molecule Axonin-1/TAG-1 mediates cell-cell interactions via homophilic and heterophilic contacts. It consists of six Ig and four fibronectin type III domains anchored to the membrane by glycosylphosphatidylinositol. The recently solved crystal structure indicates a module composed of the four N-terminal Ig domains as the contact site between trans-interacting Axonin-1 molecules from apposed membranes. Here, we have tested domain-specific monoclonal antibodies for their capacity to interfere with homophilic binding in a cell aggregation assay. The results confirmed the existence of a binding region within the N-terminal Ig domains and identified a second region contributing to homophilic binding on the third and fourth fibronectin domains near the C terminus. The perturbation of each region alone resulted in a complete loss of cell aggregation, suggesting that Axonin-1-mediated cell-cell contact results from a cooperative action of two homophilic binding regions. The data support that Axonin-1-mediated cell-cell contact is formed by cis-assisted trans-binding. The N-terminal binding regions of Axonin-1 establish a linear zipper-like string of trans-interacting Axonin-1 molecules alternately provided by the two apposed membranes. The C-terminal binding regions strengthen the cell-cell contact by enhancing the expansion of the linear string into a two-dimensional array via cis-interactions. Cis-assisted trans-binding may be a basic binding mechanism common to many cell adhesion molecules.
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the contactin related protein far 2 defines purkinje cell clusters and labels subpopulations of climbing fibers in the developing cerebellum
Molecular and Cellular Neuroscience, 2001Co-Authors: Peter Sonderegger, Christoph Rader, Jorg Freigang, Antonius Plagge, Luzie Sendtnervoelderndorff, Pinar Sirim, Thomas BrummendorfAbstract:FAR-2 is a novel neural member of the Ig superfamily, which is related to F11/F3/contactin and Axonin-1/TAG-1. This protein is expressed by subpopulations of Purkinje cells in the chicken cerebellum and FAR-2-positive clusters of these neurons alternate with FAR-2-negative clusters in both tangential dimensions of the cerebellar cortex. Furthermore, FAR-2 is also expressed by one type of Purkinje cell afferents, namely, the climbing fibers, and different subpopulations of these axons show distinct levels of FAR-2 expression. Homology modeling using Axonin-1 as a template reveals that the four aminoterminal Ig domains of FAR-2 form a compact U-shaped structure, which is likely to contain functionally important ligand-binding sites. FAR-2 is binding to the Ig superfamily protein NgCAM/L1, but not to the related receptor NrCAM, and it is also interacting with the modular ECM protein tenascin-R. These results suggest that FAR-2 may contribute to the formation of somatotopic maps of cerebellar afferents during the development of the nervous system.
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neurite fasciculation mediated by complexes of Axonin 1 and ng cell adhesion molecule
Journal of Cell Biology, 1998Co-Authors: Stefan Kunz, Beat Kunz, Lorenz Vogt, Christoph Rader, Marianne Spirig, Claudia Ginsburg, Andrea Buchstaller, Philipp Berger, Rainer B Lanz, Peter SondereggerAbstract:Neural cell adhesion molecules composed of immunoglobulin and fibronectin type III-like domains have been implicated in cell adhesion, neurite outgrowth, and fasciculation. Axonin-1 and Ng cell adhesion molecule (NgCAM), two molecules with predominantly axonal expression exhibit homophilic interactions across the extracellular space (Axonin- 1/Axonin-1 and NgCAM/NgCAM) and a heterophilic interaction (Axonin-1-NgCAM) that occurs exclusively in the plane of the same membrane (cis-interaction). Using domain deletion mutants we localized the NgCAM homophilic binding in the Ig domains 1-4 whereas heterophilic binding to Axonin-1 was localized in the Ig domains 2-4 and the third FnIII domain. The NgCAM-NgCAM interaction could be established simultaneously with the Axonin-1-NgCAM interaction. In contrast, the Axonin-1-NgCAM interaction excluded Axonin-1/Axonin-1 binding. These results and the examination of the coclustering of Axonin-1 and NgCAM at cell contacts, suggest that intercellular contact is mediated by a symmetric Axonin-12/NgCAM2 tetramer, in which homophilic NgCAM binding across the extracellular space occurs simultaneously with a cis-heterophilic interaction of Axonin-1 and NgCAM. The enhanced neurite fasciculation after overexpression of NgCAM by adenoviral vectors indicates that NgCAM is the limiting component for the formation of the Axonin-12/NgCAM2 complexes and, thus, neurite fasciculation in DRG neurons.
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Adenovirus-mediated gene transfer in neurons: construction and characterization of a vector for heterologous expression of the axonal cell adhesion molecule Axonin-1.
Journal of Neuroscience Methods, 1998Co-Authors: Roman J. Giger, Beat Kunz, Stephan Kunz, Urs Ziegler, Wim T.j.m.c. Hermens, Peter SondereggerAbstract:By homologous recombination, a first-generation adenovirus-based gene transfer vector, AdCMVax-1, was constructed as a means of manipulating the expression level of the axonal cell adhesion molecule Axonin-1 in neurons and glial cells. AdCMVax-1 harbours the entire coding region of the chicken Axonin-1 cDNA under the transcriptional control of the Cytomegalovirus enhancer/promoter in the early-region 1 of the viral genome. Characterization of AdCMVax-1 in vitro revealed highly efficient gene transfer and expression of recombinant Axonin-1 in neurons and glial cells of dissociated rat dorsal root ganglia. Similar to its native counterpart, virus-derived Axonin-1 was detected on the cell body, neurites, and growth cones of transduced neurons, occurred in a secreted and membrane-associated form, and could be cleaved from the membrane with phosphatidylinositol-specific phospholipase C. Functional characterization of recombinant Axonin-1 revealed the same binding properties as previously reported for native Axonin-1 isolated from the vitreous fluid of chicken embryos. In vivo gene transfer was studied by stereotactic injection of AdCMVax-1 in the dentate gyrus of the hippocampus and the facial nucleus in the brainstem of adult Wistar rats and revealed high level expression of recombinant Axonin-1 in a subset of hippocampal neurons and motor neurons in the facial nucleus.
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expression of the axon growth related neural adhesion molecule tag 1 Axonin 1 in the adult mouse brain
Anatomy and Embryology, 1998Co-Authors: David P. Wolfer, Roman J. Giger, Peter Sonderegger, Marijana Stagliar, Hans-peter LippAbstract:TAG-1/Axonin-1 is a neuronal cell adhesion molecule of the immunoglobulin superfamily. It is predominantly expressed during neural development and has been reported to be involved in axonal growth and pathfinding. Here, the expression of TAG-1/Axonin-1 was investigated anatomically in the adult mouse brain by in situ hybridization using digoxigenin-labeled cRNA probes. Low levels of TAG-1/Axonin-1 could be detected in cerebellar granule cells, in tufted and mitral cells of the olfactory bulb, and in pyramidal cells of area CA1 and CA3 of the hippocampus. We suspect that the expression of TAG-1/Axonin-1 in these structures of the adult brain may serve neural plasticity.
Esther T. Stoeckli - One of the best experts on this subject based on the ideXlab platform.
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Axonin 1 tag 1 is required for pathfinding of granule cell axons in the developing cerebellum
Neural Development, 2008Co-Authors: Thomas Baeriswyl, Esther T. StoeckliAbstract:Neural development consists of a series of steps, including neurogenesis, patterning, cell migration, axon guidance, and finally, synaptogenesis. Because all these steps proceed in a constantly changing environment, functional gene analyses during development have to take time into account. This is quite challenging, however, as loss-of-function approaches based on classic genetic tools do not allow for the precise temporal control that is required for developmental studies. Gene silencing by RNA interference (RNAi) in combination with the chicken embryo or with cultured embryos opens new possibilities for functional gene analysis in vivo. Axonin-1/TAG-1 is a cell adhesion molecule of the immunoglobulin superfamily with a well defined temporal and spatial expression pattern in the developing vertebrate nervous system. Axonin-1/TAG-1 was shown to promote neurite outgrowth in vitro and to be required for commissural and sensory axon pathfinding in vivo. To knock down Axonin-1 in a temporally and spatially controlled manner during development of the nervous system, we have combined RNAi with the accessibility of the chicken embryo even at late stages of development. Using ex ovo RNAi, we analyzed the function of Axonin-1/TAG-1 in cerebellar development. Axonin-1 is expressed in postmitotic granule cells while they extend their processes, the parallel fibers. In the absence of Axonin-1 these processes still extend but no longer in a parallel manner to each other or to the pial surface of the cerebellum. Axonin-1/TAG-1 is required for the navigation, but not for the elongation, of granule cell processes in the developing cerebellum in vivo.
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Axonin 1 tag 1 is required for pathfinding of granule cell axons in the developing cerebellum
Neural Development, 2008Co-Authors: Thomas Baeriswyl, Esther T. StoeckliAbstract:Background Neural development consists of a series of steps, including neurogenesis, patterning, cell migration, axon guidance, and finally, synaptogenesis. Because all these steps proceed in a constantly changing environment, functional gene analyses during development have to take time into account. This is quite challenging, however, as loss-of-function approaches based on classic genetic tools do not allow for the precise temporal control that is required for developmental studies. Gene silencing by RNA interference (RNAi) in combination with the chicken embryo or with cultured embryos opens new possibilities for functional gene analysis in vivo. Axonin-1/TAG-1 is a cell adhesion molecule of the immunoglobulin superfamily with a well defined temporal and spatial expression pattern in the developing vertebrate nervous system. Axonin-1/TAG-1 was shown to promote neurite outgrowth in vitro and to be required for commissural and sensory axon pathfinding in vivo.
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distinct subpopulations of sensory afferents require f11 or Axonin 1 for growth to their target layers within the spinal cord of the chick
Neuron, 2001Co-Authors: Florence E Perrin, Fritz G Rathjen, Esther T. StoeckliAbstract:Dorsal root ganglion neurons project axons to specific target layers in the gray matter of the spinal cord, according to their sensory modality. Using an in vivo approach, we demonstrate an involvement of the two immunoglobulin superfamily cell adhesion molecules Axonin-1/TAG-1 and F11/F3/contactin in subpopulation-specific sensory axon guidance. Proprioceptive neurons, which establish connections with motoneurons in the ventral horn, depend on F11 interactions. Nociceptive fibers, which target to layers in the dorsal horn, require Axonin-1 for pathfinding. In vitro NgCAM and NrCAM were shown to bind to both Axonin-1 and F11. However, despite this fact and despite their ubiquitous expression in the spinal cord, NgCAM and NrCAM are selective binding partners for Axonin-1 and F11 in sensory axon guidance. Whereas nociceptive pathfinding depends on NgCAM and Axonin-1, proprioceptive fibers require NrCAM and F11.
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a direct interaction of Axonin 1 with ngcam related cell adhesion molecule nrcam results in guidance but not growth of commissural axons
Journal of Cell Biology, 2000Co-Authors: Dora Fitzli, Beat Kunz, Christoph Rader, Esther T. Stoeckli, Stefan Kunz, Andrea Buchstaller, Serguei Kozlov, Kingsley Siribour, Robert P Lane, Daniel M SuterAbstract:An interaction of growth cone Axonin-1 with the floor-plate NgCAM-related cell adhesion molecule (NrCAM) was shown to play a crucial role in commissural axon guidance across the midline of the spinal cord. We now provide evidence that Axonin-1 mediates a guidance signal without promoting axon elongation. In an in vitro assay, commissural axons grew preferentially on stripes coated with a mixture of NrCAM and NgCAM. This preference was abolished in the presence of anti–Axonin-1 antibodies without a decrease in neurite length. Consistent with these findings, commissural axons in vivo only fail to extend along the longitudinal axis when both NrCAM and NgCAM interactions, but not when Axonin-1 and NrCAM or Axonin-1 and NgCAM interactions, are perturbed. Thus, we conclude that Axonin-1 is involved in guidance of commissural axons without promoting their growth.
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Interference with Axonin-1 and NrCAM Interactions Unmasks a Floor-Plate Activity Inhibitory for Commissural Axons
Neuron, 1997Co-Authors: Esther T. Stoeckli, Peter Sonderegger, G. Elisabeth Pollerberg, Lynn T. LandmesserAbstract:Axonin-1 and NrCAM were previously shown to be involved in the in vivo guidance of commissural growth cones across the floor plate of the embryonic chicken spinal cord. To further characterize their role in axon pathfinding, we developed a two-dimensional coculture system of commissural and floor-plate explants in which it was possible to study the behavior of growth cones upon floor-plate contact. Although commissural axons readily entered the floor plate under control conditions, perturbations of either Axonin-1 or NrCAM interactions prevented the growth cones from entering the floor-plate explants. The presence of antiAxonin-1 resulted in the collapse of commissural growth cones upon contact with the floor plate. The perturbation of NrCAM interactions also resulted in an avoidance of the floor plate, but without inducing growth-cone collapse. Therefore, Axonin-1 and NrCAM are crucial for the contact-mediated interaction between commissural growth cones and the floor plate, which in turn is required for the proper guidance of the axons across the ventral midline and their subsequent rostral turn into the longitudinal axis.
Christoph Rader - One of the best experts on this subject based on the ideXlab platform.
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Axonin 1 tag 1 mediates cell cell adhesion by a cis assisted trans interaction
Journal of Biological Chemistry, 2002Co-Authors: Beat Kunz, Christoph Rader, Urs Ziegler, Marianne Spirig, Ruth Lierheimer, Peter SondereggerAbstract:The neural cell adhesion molecule Axonin-1/TAG-1 mediates cell-cell interactions via homophilic and heterophilic contacts. It consists of six Ig and four fibronectin type III domains anchored to the membrane by glycosylphosphatidylinositol. The recently solved crystal structure indicates a module composed of the four N-terminal Ig domains as the contact site between trans-interacting Axonin-1 molecules from apposed membranes. Here, we have tested domain-specific monoclonal antibodies for their capacity to interfere with homophilic binding in a cell aggregation assay. The results confirmed the existence of a binding region within the N-terminal Ig domains and identified a second region contributing to homophilic binding on the third and fourth fibronectin domains near the C terminus. The perturbation of each region alone resulted in a complete loss of cell aggregation, suggesting that Axonin-1-mediated cell-cell contact results from a cooperative action of two homophilic binding regions. The data support that Axonin-1-mediated cell-cell contact is formed by cis-assisted trans-binding. The N-terminal binding regions of Axonin-1 establish a linear zipper-like string of trans-interacting Axonin-1 molecules alternately provided by the two apposed membranes. The C-terminal binding regions strengthen the cell-cell contact by enhancing the expansion of the linear string into a two-dimensional array via cis-interactions. Cis-assisted trans-binding may be a basic binding mechanism common to many cell adhesion molecules.
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the contactin related protein far 2 defines purkinje cell clusters and labels subpopulations of climbing fibers in the developing cerebellum
Molecular and Cellular Neuroscience, 2001Co-Authors: Peter Sonderegger, Christoph Rader, Jorg Freigang, Antonius Plagge, Luzie Sendtnervoelderndorff, Pinar Sirim, Thomas BrummendorfAbstract:FAR-2 is a novel neural member of the Ig superfamily, which is related to F11/F3/contactin and Axonin-1/TAG-1. This protein is expressed by subpopulations of Purkinje cells in the chicken cerebellum and FAR-2-positive clusters of these neurons alternate with FAR-2-negative clusters in both tangential dimensions of the cerebellar cortex. Furthermore, FAR-2 is also expressed by one type of Purkinje cell afferents, namely, the climbing fibers, and different subpopulations of these axons show distinct levels of FAR-2 expression. Homology modeling using Axonin-1 as a template reveals that the four aminoterminal Ig domains of FAR-2 form a compact U-shaped structure, which is likely to contain functionally important ligand-binding sites. FAR-2 is binding to the Ig superfamily protein NgCAM/L1, but not to the related receptor NrCAM, and it is also interacting with the modular ECM protein tenascin-R. These results suggest that FAR-2 may contribute to the formation of somatotopic maps of cerebellar afferents during the development of the nervous system.
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a direct interaction of Axonin 1 with ngcam related cell adhesion molecule nrcam results in guidance but not growth of commissural axons
Journal of Cell Biology, 2000Co-Authors: Dora Fitzli, Beat Kunz, Christoph Rader, Esther T. Stoeckli, Stefan Kunz, Andrea Buchstaller, Serguei Kozlov, Kingsley Siribour, Robert P Lane, Daniel M SuterAbstract:An interaction of growth cone Axonin-1 with the floor-plate NgCAM-related cell adhesion molecule (NrCAM) was shown to play a crucial role in commissural axon guidance across the midline of the spinal cord. We now provide evidence that Axonin-1 mediates a guidance signal without promoting axon elongation. In an in vitro assay, commissural axons grew preferentially on stripes coated with a mixture of NrCAM and NgCAM. This preference was abolished in the presence of anti–Axonin-1 antibodies without a decrease in neurite length. Consistent with these findings, commissural axons in vivo only fail to extend along the longitudinal axis when both NrCAM and NgCAM interactions, but not when Axonin-1 and NrCAM or Axonin-1 and NgCAM interactions, are perturbed. Thus, we conclude that Axonin-1 is involved in guidance of commissural axons without promoting their growth.
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neurite fasciculation mediated by complexes of Axonin 1 and ng cell adhesion molecule
Journal of Cell Biology, 1998Co-Authors: Stefan Kunz, Beat Kunz, Lorenz Vogt, Christoph Rader, Marianne Spirig, Claudia Ginsburg, Andrea Buchstaller, Philipp Berger, Rainer B Lanz, Peter SondereggerAbstract:Neural cell adhesion molecules composed of immunoglobulin and fibronectin type III-like domains have been implicated in cell adhesion, neurite outgrowth, and fasciculation. Axonin-1 and Ng cell adhesion molecule (NgCAM), two molecules with predominantly axonal expression exhibit homophilic interactions across the extracellular space (Axonin- 1/Axonin-1 and NgCAM/NgCAM) and a heterophilic interaction (Axonin-1-NgCAM) that occurs exclusively in the plane of the same membrane (cis-interaction). Using domain deletion mutants we localized the NgCAM homophilic binding in the Ig domains 1-4 whereas heterophilic binding to Axonin-1 was localized in the Ig domains 2-4 and the third FnIII domain. The NgCAM-NgCAM interaction could be established simultaneously with the Axonin-1-NgCAM interaction. In contrast, the Axonin-1-NgCAM interaction excluded Axonin-1/Axonin-1 binding. These results and the examination of the coclustering of Axonin-1 and NgCAM at cell contacts, suggest that intercellular contact is mediated by a symmetric Axonin-12/NgCAM2 tetramer, in which homophilic NgCAM binding across the extracellular space occurs simultaneously with a cis-heterophilic interaction of Axonin-1 and NgCAM. The enhanced neurite fasciculation after overexpression of NgCAM by adenoviral vectors indicates that NgCAM is the limiting component for the formation of the Axonin-12/NgCAM2 complexes and, thus, neurite fasciculation in DRG neurons.
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discrete clusters of Axonin 1 and ngcam at neuronal contact sites facts and speculations on the regulation of axonal fasciculation
Progress in Brain Research, 1998Co-Authors: Peter Sonderegger, Beat Kunz, Lorenz Vogt, Christoph Rader, Urs Ziegler, Stefan Kunz, Andrea Buchstaller, Philipp Berger, Serguei Kozlov, Dora FitzliAbstract:Publisher Summary Recent investigations on the molecular interactions between the neuronal cell adhesion molecules Axonin-1 and NgCAM have brought intriguing novel results suggesting that tetrameric complexes of the cell adhesion molecules Axonin-1 and NgCAM could represent functional units of cellular recognition, capable of eliciting distinctive intracellular signals depending on their structural organisation. Based on a variety of independent experimental results, it is now established that Axonin- 1 and NgCAM interact heterophilically in the plane of the axonal membrane. In neuritis without contact to other neurites, Axonin-1 and NgCAM form heterodimeric complexes. Upon membrane-membrane contacts between neuritis expressing both Axonin-I and NgCAM, higher molecular mass complexes, probably composed of two molecules of Axonin-1 and two molecules of NgCAM, are formed. Concomitant with the formation of the presumptive tetrameric complexes during neurite fasciculation, a reduction of the Axonin- 1 -associated tyrosine kinase fyn and an increase in the activity of the NgCAM-associated casein kinase II is observed. Based on the currently known structural features and binding site locations “unsaturated” complexes in which two Axonin- l/NgCAM heterodimers of apposed membranes would be joined to a heterotetrarneric complex either by a homophilic Axonin- 1 /Axonin-1 or a homophilic NgCAM/NgCAM interaction are proposed. The possibility that differences in the concentrations of Axonin-1 and NgCAM, as well as the factors regulating the binding affinities of Axonin-1 and NgCAM might regulate the generation of structurally distinctive tetrameric complexes at membrane-membrane contact sites, raises speculations about a possible regulatory function of the Axonin- l/NgCAM complexes in selection mechanisms of neuritis, such as preference determination for fasciculation or pathway choice at bifurcations.
Roman J. Giger - One of the best experts on this subject based on the ideXlab platform.
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Adenovirus-mediated gene transfer in neurons: construction and characterization of a vector for heterologous expression of the axonal cell adhesion molecule Axonin-1.
Journal of Neuroscience Methods, 1998Co-Authors: Roman J. Giger, Beat Kunz, Stephan Kunz, Urs Ziegler, Wim T.j.m.c. Hermens, Peter SondereggerAbstract:By homologous recombination, a first-generation adenovirus-based gene transfer vector, AdCMVax-1, was constructed as a means of manipulating the expression level of the axonal cell adhesion molecule Axonin-1 in neurons and glial cells. AdCMVax-1 harbours the entire coding region of the chicken Axonin-1 cDNA under the transcriptional control of the Cytomegalovirus enhancer/promoter in the early-region 1 of the viral genome. Characterization of AdCMVax-1 in vitro revealed highly efficient gene transfer and expression of recombinant Axonin-1 in neurons and glial cells of dissociated rat dorsal root ganglia. Similar to its native counterpart, virus-derived Axonin-1 was detected on the cell body, neurites, and growth cones of transduced neurons, occurred in a secreted and membrane-associated form, and could be cleaved from the membrane with phosphatidylinositol-specific phospholipase C. Functional characterization of recombinant Axonin-1 revealed the same binding properties as previously reported for native Axonin-1 isolated from the vitreous fluid of chicken embryos. In vivo gene transfer was studied by stereotactic injection of AdCMVax-1 in the dentate gyrus of the hippocampus and the facial nucleus in the brainstem of adult Wistar rats and revealed high level expression of recombinant Axonin-1 in a subset of hippocampal neurons and motor neurons in the facial nucleus.
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expression of the axon growth related neural adhesion molecule tag 1 Axonin 1 in the adult mouse brain
Anatomy and Embryology, 1998Co-Authors: David P. Wolfer, Roman J. Giger, Peter Sonderegger, Marijana Stagliar, Hans-peter LippAbstract:TAG-1/Axonin-1 is a neuronal cell adhesion molecule of the immunoglobulin superfamily. It is predominantly expressed during neural development and has been reported to be involved in axonal growth and pathfinding. Here, the expression of TAG-1/Axonin-1 was investigated anatomically in the adult mouse brain by in situ hybridization using digoxigenin-labeled cRNA probes. Low levels of TAG-1/Axonin-1 could be detected in cerebellar granule cells, in tufted and mitral cells of the olfactory bulb, and in pyramidal cells of area CA1 and CA3 of the hippocampus. We suspect that the expression of TAG-1/Axonin-1 in these structures of the adult brain may serve neural plasticity.
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implications for the domain arrangement of Axonin 1 derived from the mapping of its ngcam binding site
The EMBO Journal, 1996Co-Authors: Christoph Rader, Roman J. Giger, Beat Kunz, Philipp Berger, Ruth Lierheimer, Peter Tittmann, Heinz Gross, Peter SondereggerAbstract:The neuronal cell adhesion molecule Axonin-1 is composed of six immunoglobulin and four fibronectin type III domains. Axonin-1 promotes neurite outgrowth, when presented as a substratum for neurons in vitro, via a neuronal receptor that has been identified as the neuron-glia cell adhesion molecule, NgCAM, based on the blocking effect of polyclonal antibodies directed to NgCAM. Here we report the identification of Axonin-1 domains involved in NgCAM binding. NgCAM-conjugated microspheres were tested for binding to COS cells expressing domain deletion mutants of Axonin-1. In addition, monoclonal antibodies directed to Axonin-1 were assessed for their ability to block the Axonin-1-NgCAM interaction, and their epitopes were mapped using the domain deletion mutants. The results suggest that the four amino-terminal immunoglobulin domains of Axonin-1 form a domain conglomerate which is necessary and sufficient for NgCAM binding. Surprisingly, NgCAM binding to membrane-bound Axonin-1 was increased strongly by deletion of the fifth or sixth immunoglobulin domains of Axonin-1. Based on these results and on negative staining electron microscopy, we propose a horseshoe-shaped domain arrangement of Axonin-1 that obscures the NgCAM binding site. Neurite outgrowth studies with truncated forms of Axonin-1 show that Axonin-1 is a neurite outgrowth-promoting substratum in the absence of the NgCAM binding site.
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differential expression of the mrnas of the axonal glycoproteins Axonin 1 and ngcam in the developing chick retina
Developmental Brain Research, 1996Co-Authors: Patrizia Morino, Roman J. Giger, Peter Sonderegger, Andrea Buchstaller, Günter RagerAbstract:Cell adhesion molecules expressed on the axonal membrane have been thought to be involved in the guidance of axons to their target area. In the chick, Axonin-1 and NgCAM have been shown to promote, through reciprocal interactions, neurite outgrowth in vitro. We have recently shown that chick retinal ganglion cells (RGC) express both proteins as early as the axonal elongation begins. Their expression continues throughout the development of the retinotectal system synchronously with the chronotopic spread of axons. To further investigate the spatiotemporal distribution of Axonin-1 and NgCAM in the retina, we have analysed the expression of their mRNAs in the present study. From stage 36 (E10) until hatching photoreceptors express Axonin-1 but not NgCAM. In the inner nuclear layer groups of amacrine cells were strongly labelled with both probes but they seemed to belong to different subgroups. These patterns of expression might indicate a differential influence of the two proteins on the development of the local neural circuits of the retina.
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the human tax1 gene encoding the axon associated cell adhesion molecule tag 1 Axonin 1 genomic structure and basic promoter
Genomics, 1995Co-Authors: Serguei Kozlov, Roman J. Giger, Thomas Hasler, Elena Korvatska, Daniel F Schorderet, Peter SondereggerAbstract:The human TAX-1 gene (HGMW-approved symbol TAX1) is located on chromosome 1 (1q32.1) and encodes the neuronal cell adhesion molecule TAG-1/Axonin-1. The gene product, termed TAG-1 in the rat and Axonin-1 in the chicken, is composed of six immunoglobulin (Ig)-like and four fibronectin type III (FNIII)-like domains. It is found predominantly on the axons of particular nerve fiber tracts during neural development, and it has been demonstrated to function as a potent substratum for neurite outgrowth in vitro. Here we report the cloning and structural characterization of the TAX-1 gene. The transcribed region of the TAX-1 gene extends over about 40 kb. Like its chicken homologue, the human TAX-1 gene consists of 23 exons. Two GT/CA microsatellites were localized in the first intron; a polymorphism was found for one of them. Reporter gene analysis with serially truncated fragments of the 5'-flanking region indicated that a 164-bp fragment located immediately upstream of the putative transcription initiation site was sufficient to function as a basal promoter.
Beat Kunz - One of the best experts on this subject based on the ideXlab platform.
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Axonin 1 tag 1 mediates cell cell adhesion by a cis assisted trans interaction
Journal of Biological Chemistry, 2002Co-Authors: Beat Kunz, Christoph Rader, Urs Ziegler, Marianne Spirig, Ruth Lierheimer, Peter SondereggerAbstract:The neural cell adhesion molecule Axonin-1/TAG-1 mediates cell-cell interactions via homophilic and heterophilic contacts. It consists of six Ig and four fibronectin type III domains anchored to the membrane by glycosylphosphatidylinositol. The recently solved crystal structure indicates a module composed of the four N-terminal Ig domains as the contact site between trans-interacting Axonin-1 molecules from apposed membranes. Here, we have tested domain-specific monoclonal antibodies for their capacity to interfere with homophilic binding in a cell aggregation assay. The results confirmed the existence of a binding region within the N-terminal Ig domains and identified a second region contributing to homophilic binding on the third and fourth fibronectin domains near the C terminus. The perturbation of each region alone resulted in a complete loss of cell aggregation, suggesting that Axonin-1-mediated cell-cell contact results from a cooperative action of two homophilic binding regions. The data support that Axonin-1-mediated cell-cell contact is formed by cis-assisted trans-binding. The N-terminal binding regions of Axonin-1 establish a linear zipper-like string of trans-interacting Axonin-1 molecules alternately provided by the two apposed membranes. The C-terminal binding regions strengthen the cell-cell contact by enhancing the expansion of the linear string into a two-dimensional array via cis-interactions. Cis-assisted trans-binding may be a basic binding mechanism common to many cell adhesion molecules.
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a direct interaction of Axonin 1 with ngcam related cell adhesion molecule nrcam results in guidance but not growth of commissural axons
Journal of Cell Biology, 2000Co-Authors: Dora Fitzli, Beat Kunz, Christoph Rader, Esther T. Stoeckli, Stefan Kunz, Andrea Buchstaller, Serguei Kozlov, Kingsley Siribour, Robert P Lane, Daniel M SuterAbstract:An interaction of growth cone Axonin-1 with the floor-plate NgCAM-related cell adhesion molecule (NrCAM) was shown to play a crucial role in commissural axon guidance across the midline of the spinal cord. We now provide evidence that Axonin-1 mediates a guidance signal without promoting axon elongation. In an in vitro assay, commissural axons grew preferentially on stripes coated with a mixture of NrCAM and NgCAM. This preference was abolished in the presence of anti–Axonin-1 antibodies without a decrease in neurite length. Consistent with these findings, commissural axons in vivo only fail to extend along the longitudinal axis when both NrCAM and NgCAM interactions, but not when Axonin-1 and NrCAM or Axonin-1 and NgCAM interactions, are perturbed. Thus, we conclude that Axonin-1 is involved in guidance of commissural axons without promoting their growth.
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neurite fasciculation mediated by complexes of Axonin 1 and ng cell adhesion molecule
Journal of Cell Biology, 1998Co-Authors: Stefan Kunz, Beat Kunz, Lorenz Vogt, Christoph Rader, Marianne Spirig, Claudia Ginsburg, Andrea Buchstaller, Philipp Berger, Rainer B Lanz, Peter SondereggerAbstract:Neural cell adhesion molecules composed of immunoglobulin and fibronectin type III-like domains have been implicated in cell adhesion, neurite outgrowth, and fasciculation. Axonin-1 and Ng cell adhesion molecule (NgCAM), two molecules with predominantly axonal expression exhibit homophilic interactions across the extracellular space (Axonin- 1/Axonin-1 and NgCAM/NgCAM) and a heterophilic interaction (Axonin-1-NgCAM) that occurs exclusively in the plane of the same membrane (cis-interaction). Using domain deletion mutants we localized the NgCAM homophilic binding in the Ig domains 1-4 whereas heterophilic binding to Axonin-1 was localized in the Ig domains 2-4 and the third FnIII domain. The NgCAM-NgCAM interaction could be established simultaneously with the Axonin-1-NgCAM interaction. In contrast, the Axonin-1-NgCAM interaction excluded Axonin-1/Axonin-1 binding. These results and the examination of the coclustering of Axonin-1 and NgCAM at cell contacts, suggest that intercellular contact is mediated by a symmetric Axonin-12/NgCAM2 tetramer, in which homophilic NgCAM binding across the extracellular space occurs simultaneously with a cis-heterophilic interaction of Axonin-1 and NgCAM. The enhanced neurite fasciculation after overexpression of NgCAM by adenoviral vectors indicates that NgCAM is the limiting component for the formation of the Axonin-12/NgCAM2 complexes and, thus, neurite fasciculation in DRG neurons.
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Adenovirus-mediated gene transfer in neurons: construction and characterization of a vector for heterologous expression of the axonal cell adhesion molecule Axonin-1.
Journal of Neuroscience Methods, 1998Co-Authors: Roman J. Giger, Beat Kunz, Stephan Kunz, Urs Ziegler, Wim T.j.m.c. Hermens, Peter SondereggerAbstract:By homologous recombination, a first-generation adenovirus-based gene transfer vector, AdCMVax-1, was constructed as a means of manipulating the expression level of the axonal cell adhesion molecule Axonin-1 in neurons and glial cells. AdCMVax-1 harbours the entire coding region of the chicken Axonin-1 cDNA under the transcriptional control of the Cytomegalovirus enhancer/promoter in the early-region 1 of the viral genome. Characterization of AdCMVax-1 in vitro revealed highly efficient gene transfer and expression of recombinant Axonin-1 in neurons and glial cells of dissociated rat dorsal root ganglia. Similar to its native counterpart, virus-derived Axonin-1 was detected on the cell body, neurites, and growth cones of transduced neurons, occurred in a secreted and membrane-associated form, and could be cleaved from the membrane with phosphatidylinositol-specific phospholipase C. Functional characterization of recombinant Axonin-1 revealed the same binding properties as previously reported for native Axonin-1 isolated from the vitreous fluid of chicken embryos. In vivo gene transfer was studied by stereotactic injection of AdCMVax-1 in the dentate gyrus of the hippocampus and the facial nucleus in the brainstem of adult Wistar rats and revealed high level expression of recombinant Axonin-1 in a subset of hippocampal neurons and motor neurons in the facial nucleus.
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discrete clusters of Axonin 1 and ngcam at neuronal contact sites facts and speculations on the regulation of axonal fasciculation
Progress in Brain Research, 1998Co-Authors: Peter Sonderegger, Beat Kunz, Lorenz Vogt, Christoph Rader, Urs Ziegler, Stefan Kunz, Andrea Buchstaller, Philipp Berger, Serguei Kozlov, Dora FitzliAbstract:Publisher Summary Recent investigations on the molecular interactions between the neuronal cell adhesion molecules Axonin-1 and NgCAM have brought intriguing novel results suggesting that tetrameric complexes of the cell adhesion molecules Axonin-1 and NgCAM could represent functional units of cellular recognition, capable of eliciting distinctive intracellular signals depending on their structural organisation. Based on a variety of independent experimental results, it is now established that Axonin- 1 and NgCAM interact heterophilically in the plane of the axonal membrane. In neuritis without contact to other neurites, Axonin-1 and NgCAM form heterodimeric complexes. Upon membrane-membrane contacts between neuritis expressing both Axonin-I and NgCAM, higher molecular mass complexes, probably composed of two molecules of Axonin-1 and two molecules of NgCAM, are formed. Concomitant with the formation of the presumptive tetrameric complexes during neurite fasciculation, a reduction of the Axonin- 1 -associated tyrosine kinase fyn and an increase in the activity of the NgCAM-associated casein kinase II is observed. Based on the currently known structural features and binding site locations “unsaturated” complexes in which two Axonin- l/NgCAM heterodimers of apposed membranes would be joined to a heterotetrarneric complex either by a homophilic Axonin- 1 /Axonin-1 or a homophilic NgCAM/NgCAM interaction are proposed. The possibility that differences in the concentrations of Axonin-1 and NgCAM, as well as the factors regulating the binding affinities of Axonin-1 and NgCAM might regulate the generation of structurally distinctive tetrameric complexes at membrane-membrane contact sites, raises speculations about a possible regulatory function of the Axonin- l/NgCAM complexes in selection mechanisms of neuritis, such as preference determination for fasciculation or pathway choice at bifurcations.