Initiation of sodium channel clustering at the node of Ranvier in the mouse optic nerve |
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Authors: | Ishibashi Tomoko Ikenaka Kazuhiro Shimizu Takeshi Kagawa Tetshushi Baba Hiroko |
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Institution: | (1) Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, 444-8585, Japan;(2) Department of Molecular Neurobiology, School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, 192-0392, Japan;(3) Laboratory of Neural Information, National Institute for Physiological Sciences, Japan;(4) Okazaki National Research Institutes, Okazaki, 444-8585, Japan;(5) Department of Molecular Neurobiology, School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, 192-0392, Japan |
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Abstract: | Ion fluxes in mammalian myelinated axons are restricted to the nodes of Ranvier, where, in particular, voltage-gated Na+ channels are clustered at a high density. The node of Ranvier is separated from the internode by two distinct domains of the axolemma, the paranode and the juxtaparanode. Each axonal domain is characterized by the presence of a specific protein complex. Although oligodendrocytes and/or myelin membranes are believed to play some instructive roles in the organization of axonal domains, the mechanisms leading to their localized distribution are not well understood. In this paper we focused on the involvement of myelin sheaths in this domain organization and examined the distribution of axonal components in the optic nerves of wild type, hypomyelinating jimpy mice and demyelinating PLP transgenic mice. The results showed that the clustering of Na+ channels does not require junction-like structures to be formed between the glial processes and axons, but requires mature oligodendrocytes to be present in close vicinity. |
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Keywords: | Node of Ranvier Na+ channel optic nerve myelin |
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