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Yoshikawa F, Sato Y, Tohyama K, Akagi T, Hashikawa T, Nagakura-Takagi Y, Sekine Y, Morita N, Baba H, Suzuki Y, Sugano S, Sato A, Furuichi T. Opalin, a transmembrane sialylglycoprotein located in the central nervous system myelin paranodal loop membrane. J Biol Chem 2008; 283:20830-40. [PMID: 18490449 PMCID: PMC3258930 DOI: 10.1074/jbc.m801314200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 04/22/2008] [Indexed: 01/13/2023] Open
Abstract
In contrast to compact myelin, the series of paranodal loops located in the outermost lateral region of myelin is non-compact; the intracellular space is filled by a continuous channel of cytoplasm, the extracellular surfaces between neighboring loops keep a definite distance, but the loop membranes have junctional specializations. Although the proteins that form compact myelin have been well studied, the protein components of paranodal loop membranes are not fully understood. This report describes the biochemical characterization and expression of Opalin as a novel membrane protein in paranodal loops. Mouse Opalin is composed of a short N-terminal extracellular domain (amino acid residues 1-30), a transmembrane domain (residues 31-53), and a long C-terminal intracellular domain (residues 54-143). Opalin is enriched in myelin of the central nervous system, but not that of the peripheral nervous system of mice. Enzymatic deglycosylation showed that myelin Opalin contained N- and O-glycans, and that the O-glycans, at least, had negatively charged sialic acids. We identified two N-glycan sites at Asn-6 and Asn-12 and an O-glycan site at Thr-14 in the extracellular domain. Site-directed mutations at the glycan sites impaired the cell surface localization of Opalin. In addition to the somata and processes of oligodendrocytes, Opalin immunoreactivity was observed in myelinated axons in a spiral fashion, and was concentrated in the paranodal loop region. Immunogold electron microscopy demonstrated that Opalin was localized at particular sites in the paranodal loop membrane. These results suggest a role for highly sialylglycosylated Opalin in an intermembranous function of the myelin paranodal loops in the central nervous system.
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Affiliation(s)
- Fumio Yoshikawa
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Yumi Sato
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Koujiro Tohyama
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Takumi Akagi
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Tsutomu Hashikawa
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Yuko Nagakura-Takagi
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Yukiko Sekine
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Noriyuki Morita
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Hiroko Baba
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Yutaka Suzuki
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Sumio Sugano
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Akira Sato
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
| | - Teiichi Furuichi
- Laboratory for Molecular Neurogenesis and
Laboratory for Neural Architecture, RIKEN Brain
Science Institute, Wako 351-0198, The Center for
Electron Microscopy and Bio-Imaging Research, Iwate Medical University,
Morioka 020-8505, the Tokyo University of
Pharmacy and Life Sciences, Hachioji 192-0392, and the
Department of Frontier Science, University of Tokyo,
Tokyo 108-8639, Japan
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Nobile C, Hinzmann B, Scannapieco P, Siebert R, Zimbello R, Perez-Tur J, Sarafidou T, Moschonas NK, French L, Deloukas P, Ciccodicola A, Gesk S, Poza JJ, Lo Nigro C, Seri M, Schlegelberger B, Rosenthal A, Valle G, Lopez de Munain A, Tassinari CA, Michelucci R. Identification and characterization of a novel human brain-specific gene, homologous to S. scrofa tmp83.5, in the chromosome 10q24 critical region for temporal lobe epilepsy and spastic paraplegia. Gene 2002; 282:87-94. [PMID: 11814680 DOI: 10.1016/s0378-1119(01)00846-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We describe the structure, genomic organization, and some transcription features of a human brain-specific gene previously localized to the genomic region involved in temporal lobe epilepsy and spastic paraplegia on chromosome 10q24. The gene, which consists of six exons disseminated over 16 kb of genomic DNA, is highly homologous to the porcine tmp83.5 gene and encodes a putative transmembrane protein of 141 amino acids. Unlike its porcine homolog, from which two mRNAs with different 5'-sequences are transcribed, the human gene apparently encodes three mRNA species with 3'-untranslated regions of different sizes. Mutation analysis of its coding sequence in families affected with temporal lobe epilepsy or spastic paraplegia linked to 10q24 do not support the involvement of this gene in either diseases.
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Affiliation(s)
- C Nobile
- CNR-Centro di Studio per la Biologia e Fisiopatologia Muscolare, Dipartimento di Scienze Biomediche Sperimentali, Viale G. Colombo 3, 35121 Padova, Italy.
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