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Axonal Cell

The Experts below are selected from a list of 126 Experts worldwide ranked by ideXlab platform

Peter Sonderegger – 1st expert on this subject based on the ideXlab platform

  • 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, 1998
    Co-Authors: Roman J. Giger, Urs Ziegler, Wim T.j.m.c. Hermens, Beat Kunz, Stephan Kunz, Peter Sonderegger

    Abstract:

    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.

  • Expression of the Axonal Cell adhesion molecules axonin-1 and Ng-CAM during the development of the chick retinotectal system.
    The Journal of Comparative Neurology, 1996
    Co-Authors: Günter Rager, Patrizia Morino, Jutta Schnitzer, Peter Sonderegger

    Abstract:

    Cell surface glycoproteins expressed on growth cones and axons during brain development have been postulated to be involved in the CellCell interactions that guide axons into their target area. Nevertheless, an unequivocal description of the mechanism by which such molecules exert control over the pathway of a growing axon has not been done. As a crucial requirement in support of a relevant involvement of an Axonal surface molecule in growth cone guidance, this molecule should be expressed in the growth cone. The developing retinotectal system provides an exCellent opportunity to test whether a particular neuronal surface molecule fulfills the requirement of the spatiotemporal coincidence between its appearance and the emergence of growth cones because its setup follows the rule of chronotopy, i.e., the position of axons in a certain site is determined by the time of their arrival. We have analyzed axonin-1 and the neuron-glia Cell adhesion molecule (Ng-CAM), two Axonal surface molecules that promote neurite growth in vitro, for their expression in the retina and in the retinotectal system of the chick throughout its development. At stage 18, both axonin-like (A-LI) and Ng-CAM-like immunoreactivity (Ng-CAM-LI) are clearly present in the area where first retinal ganglion Cells (RGCs) are generated. The immunoreactivity spreads synchronously with the formation of RGCs over the developing retina. From stage 32 on, the inner plexiform layer is also stained according to its temporospatial gradient of maturation. In later stages, the outer plexiform layer and the inner segments of photoreceptors also show immunoreactivity. The development of A-LI and Ng-CAM-LI along the optic nerve, chiasm, optic tract, and in the superficial layers of the optic tectum follows the chronotopic pattern of axons, as was found by earlier morphological investigations. Older axons loose their A-LI. This allows to localize the position of newly formed axons. The fact that A-LI and Ng-CAM-LI parallel the formation and maturation of axons suggests that axonin-1 and Ng-CAM may play an important role in the organization of the retinotectal system.

  • The Gene of Chicken Axonin-1
    FEBS Journal, 1995
    Co-Authors: Roman J. Giger, Lorenz Vogt, Richard A. Zuellig, Christoph Rader, Anne Henehan-beatty, David P. Wolfer, Peter Sonderegger

    Abstract:

    We have isolated and characterised the gene encoding the chicken Axonal Cell adhesion molecule axonin-1. This gene comprises 23 exons distributed over approximately 40 kb. Each of the six immunoglobulin-like domains and the four fibronectin-type-III-like domains of axonin-1 is encoded by two exons. The introns between two domains are exclusively phase I. Their exonintron borders correspond to the domain borders of the protein, suggesting that the gene of axonin-1 had been generated by exon shuffling. Three transcripts with a length of 4.3 kb, 5 kb, and 8 kb are found, and we provide evidence that they result from alternative use of polyadenylation signals. In situ hybridization revealed co-localisation of these transcripts in time and space in the developing chicken retina. Several identical transcription initiation sites were found in retina, brain, and cerebellum by RNase protection assay and anchored polymerase chain reaction. By transfection of HeLa Cells, rat PC-12 phaeochromocytoma Cells, and chicken embryonic fibroblasts with serially truncated segments of the 5′-flanking region linked to a luciferase reporter gene, we have found that the sequence from −91 to +56 relative to the transcription initiation site is sufficient to promote efficient gene expression. Tissue-specific expression of the axonin-1 gene seems to be regulated in part by sequences more than 1 kb upstream of the transcription initiation site. As revealed by computer analysis, the sequence immediately upstream of exon 1 contains an AP-2 binding site, a tumor phorbol-ester-responsive element, and a homeodomain protein binding site, but no canonical TATA box. A second AP-2 binding site and a homeodomain protein binding site are located within exon 1.

Robert C. Foehring – 2nd expert on this subject based on the ideXlab platform

  • Expression and biophysical properties of Kv1 channels in supragranular neocortical pyramidal neurones
    The Journal of Physiology, 2006
    Co-Authors: Dongxu Guan, Tatiana Tkatch, D.j. Surmeier, William E. Armstrong, Robert C. Foehring

    Abstract:

    Potassium channels are extremely diverse regulators of neuronal excitability. As part of an investigation into how this molecular diversity is utilized by neurones, we examined the expression and biophysical properties of native Kv1 channels in layer II/III pyramidal neurones from somatosensory and motor cortex. Single-Cell RT-PCR, immunocytochemistry, and whole Cell recordings with specific peptide toxins revealed that individual pyramidal Cells express multiple Kv1 α-subunits. The most abundant subunit mRNAs were Kv1.1 > 1.2 > 1.4 > 1.3. All of these subunits were localized to somatodendritic as well as Axonal Cell compartments. These data suggest variability in the subunit complexion of Kv1 channels in these Cells. The α-dendrotoxin (α-DTX)-sensitive current activated more rapidly and at more negative potentials than the α-DTX-insensitive current, was first observed at voltages near action potential threshold, and was relatively insensitive to holding potential. The α-DTX-sensitive current comprised about 10% of outward current at steady-state, in response to steps from −70 mV. From −50 mV, this percentage increased to ∼20%. All Cells expressed an α-DTX-sensitive current with slow inactivation kinetics. In some Cells a transient component was also present. Deactivation kinetics were voltage dependent, such that deactivation was slow at potentials traversed by interspike intervals during repetitive firing. Because of its kinetics and voltage dependence, the α-DTX-sensitive current should be most important at physiological resting potentials and in response to brief stimuli. Kv1 channels should also be important at voltages near threshold and corresponding to interspike intervals.

  • Expression and biophysical properties of Kv1 channels in supragranular neocortical pyramidal neurones.
    The Journal of physiology, 2005
    Co-Authors: Dongxu Guan, Tatiana Tkatch, D.j. Surmeier, William E. Armstrong, Robert C. Foehring

    Abstract:

    Potassium channels are extremely diverse regulators of neuronal excitability. As part of an investigation into how this molecular diversity is utilized by neurones, we examined the expression and biophysical properties of native Kv1 channels in layer II/III pyramidal neurones from somatosensory and motor cortex. Single-Cell RT-PCR, immunocytochemistry, and whole Cell recordings with specific peptide toxins revealed that individual pyramidal Cells express multiple Kv1 alpha-subunits. The most abundant subunit mRNAs were Kv1.1 > 1.2 > 1.4 > 1.3. All of these subunits were localized to somatodendritic as well as Axonal Cell compartments. These data suggest variability in the subunit complexion of Kv1 channels in these Cells. The alpha-dendrotoxin (alpha-DTX)-sensitive current activated more rapidly and at more negative potentials than the alpha-DTX-insensitive current, was first observed at voltages near action potential threshold, and was relatively insensitive to holding potential. The alpha-DTX-sensitive current comprised about 10% of outward current at steady-state, in response to steps from -70 mV. From -50 mV, this percentage increased to approximately 20%. All Cells expressed an alpha-DTX-sensitive current with slow inactivation kinetics. In some Cells a transient component was also present. Deactivation kinetics were voltage dependent, such that deactivation was slow at potentials traversed by interspike intervals during repetitive firing. Because of its kinetics and voltage dependence, the alpha-DTX-sensitive current should be most important at physiological resting potentials and in response to brief stimuli. Kv1 channels should also be important at voltages near threshold and corresponding to interspike intervals.

Roman J. Giger – 3rd expert on this subject based on the ideXlab platform

  • 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, 1998
    Co-Authors: Roman J. Giger, Urs Ziegler, Wim T.j.m.c. Hermens, Beat Kunz, Stephan Kunz, Peter Sonderegger

    Abstract:

    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.

  • The Gene of Chicken Axonin-1
    FEBS Journal, 1995
    Co-Authors: Roman J. Giger, Lorenz Vogt, Richard A. Zuellig, Christoph Rader, Anne Henehan-beatty, David P. Wolfer, Peter Sonderegger

    Abstract:

    We have isolated and characterised the gene encoding the chicken Axonal Cell adhesion molecule axonin-1. This gene comprises 23 exons distributed over approximately 40 kb. Each of the six immunoglobulin-like domains and the four fibronectin-type-III-like domains of axonin-1 is encoded by two exons. The introns between two domains are exclusively phase I. Their exonintron borders correspond to the domain borders of the protein, suggesting that the gene of axonin-1 had been generated by exon shuffling. Three transcripts with a length of 4.3 kb, 5 kb, and 8 kb are found, and we provide evidence that they result from alternative use of polyadenylation signals. In situ hybridization revealed co-localisation of these transcripts in time and space in the developing chicken retina. Several identical transcription initiation sites were found in retina, brain, and cerebellum by RNase protection assay and anchored polymerase chain reaction. By transfection of HeLa Cells, rat PC-12 phaeochromocytoma Cells, and chicken embryonic fibroblasts with serially truncated segments of the 5′-flanking region linked to a luciferase reporter gene, we have found that the sequence from −91 to +56 relative to the transcription initiation site is sufficient to promote efficient gene expression. Tissue-specific expression of the axonin-1 gene seems to be regulated in part by sequences more than 1 kb upstream of the transcription initiation site. As revealed by computer analysis, the sequence immediately upstream of exon 1 contains an AP-2 binding site, a tumor phorbol-ester-responsive element, and a homeodomain protein binding site, but no canonical TATA box. A second AP-2 binding site and a homeodomain protein binding site are located within exon 1.

  • The gene of chicken axonin-1. Complete structure and analysis of the promoter.
    FEBS Journal, 1995
    Co-Authors: Roman J. Giger, Lorenz Vogt, Richard A. Zuellig, Christoph Rader, Anne Henehan-beatty, David P. Wolfer, Peter Sonderegger

    Abstract:

    : We have isolated and characterised the gene encoding the chicken Axonal Cell adhesion molecule axonin-1. This gene comprises 23 exons distributed over approximately 40 kb. Each of the six immunoglobulin-like domains and the four fibronectin-type-III-like domains of axonin-1 is encoded by two exons. The introns between two domains are exclusively phase I. Their exon/intron borders correspond to the domain borders of the protein, suggesting that the gene of axonin-1 had been generated by exon shuffling. Three transcripts with a length of 4.3 kb, 5 kb, and 8 kb are found, and we provide evidence that they result from alternative use of polyadenylation signals. In situ hybridization revealed co-localisation of these transcripts in time and space in the developing chicken retina. Several identical transcription initiation sites were found in retina, brain, and cerebellum by RNase protection assay and anchored polymerase chain reaction. By transfection of HeLa Cells, rat PC-12 phaeochromocytoma Cells, and chicken embryonic fibroblasts with serially truncated segments of the 5′-flanking region linked to a luciferase reporter gene, we have found that the sequence from -91 to +56 relative to the transcription initiation site is sufficient to promote efficient gene expression. Tissue-specific expression of the axonin-1 gene seems to be regulated in part by sequences more than 1 kb upstream of the transcription initiation site. As revealed by computer analysis, the sequence immediately upstream of exon 1 contains an AP-2 binding site, a tumor phorbol-ester-responsive element, and a homeodomain protein binding site, but no canonical TATA box. A second AP-2 binding site and a homeodomain protein binding site are located within exon 1.