1
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Chataigner LMP, Thärichen L, Beugelink JW, Granneman JCM, Mokiem NJ, Snijder J, Förster F, Janssen BJC. Contactin 2 homophilic adhesion structure and conformational plasticity. Structure 2024; 32:60-73.e5. [PMID: 37992710 DOI: 10.1016/j.str.2023.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/27/2023] [Accepted: 10/26/2023] [Indexed: 11/24/2023]
Abstract
The cell-surface attached glycoprotein contactin 2 is ubiquitously expressed in the nervous system and mediates homotypic cell-cell interactions to organize cell guidance, differentiation, and adhesion. Contactin 2 consists of six Ig and four fibronectin type III domains (FnIII) of which the first four Ig domains form a horseshoe structure important for homodimerization and oligomerization. Here we report the crystal structure of the six-domain contactin 2Ig1-6 and show that the Ig5-Ig6 combination is oriented away from the horseshoe with flexion in interdomain connections. Two distinct dimer states, through Ig1-Ig2 and Ig3-Ig6 interactions, together allow formation of larger oligomers. Combined size exclusion chromatography with multiangle light scattering (SEC-MALS), small-angle X-ray scattering (SAXS) and native MS analysis indicates contactin 2Ig1-6 oligomerizes in a glycan dependent manner. SAXS and negative-stain electron microscopy reveals inherent plasticity of the contactin 2 full-ectodomain. The combination of intermolecular binding sites and ectodomain plasticity explains how contactin 2 can function as a homotypic adhesion molecule in diverse intercellular environments.
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Affiliation(s)
- Lucas M P Chataigner
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, the Netherlands
| | - Lena Thärichen
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, the Netherlands
| | - J Wouter Beugelink
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, the Netherlands
| | - Joke C M Granneman
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, the Netherlands
| | - Nadia J Mokiem
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, Utrecht 3584 CH, the Netherlands
| | - Joost Snijder
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, Utrecht 3584 CH, the Netherlands
| | - Friedrich Förster
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, the Netherlands
| | - Bert J C Janssen
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, the Netherlands.
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2
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Chang C, Sell LB, Shi Q, Bhat MA. Mouse models of human CNTNAP1-associated congenital hypomyelinating neuropathy and genetic restoration of murine neurological deficits. Cell Rep 2023; 42:113274. [PMID: 37862170 PMCID: PMC10873044 DOI: 10.1016/j.celrep.2023.113274] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 08/14/2023] [Accepted: 09/28/2023] [Indexed: 10/22/2023] Open
Abstract
The Contactin-associated protein 1 (Cntnap1) mouse mutants fail to establish proper axonal domains in myelinated axons. Human CNTNAP1 mutations are linked to hypomyelinating neuropathy-3, which causes severe neurological deficits. To understand the human neuropathology and to model human CNTNAP1C323R and CNTNAP1R764C mutations, we generated Cntnap1C324R and Cntnap1R765C mouse mutants, respectively. Both Cntnap1 mutants show weight loss, reduced nerve conduction, and progressive motor dysfunction. The paranodal ultrastructure shows everted myelin loops and the absence of axo-glial junctions. Biochemical analysis reveals that these Cntnap1 mutant proteins are nearly undetectable in the paranodes, have reduced surface expression and stability, and are retained in the neuronal soma. Postnatal transgenic expression of Cntnap1 in the mutant backgrounds rescues the phenotypes and restores the organization of axonal domains with improved motor function. This study uncovers the mechanistic impact of two human CNTNAP1 mutations in a mouse model and provides proof of concept for gene therapy for CNTNAP1 patients.
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Affiliation(s)
- Cheng Chang
- Department of Cellular and Integrative Physiology University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA; The Second Xiangya Hospital of Central South University, Changsha 410011, Hunan, China
| | - Lacey B Sell
- Department of Cellular and Integrative Physiology University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA; IBMS Neuroscience Graduate Program, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Qian Shi
- Department of Cellular and Integrative Physiology University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA; IBMS Neuroscience Graduate Program, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA; IBMS Neuroscience Graduate Program, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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3
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Pinatel D, Pearlstein E, Bonetto G, Goutebroze L, Karagogeos D, Crepel V, Faivre-Sarrailh C. A class-specific effect of dysmyelination on the excitability of hippocampal interneurons. eLife 2023; 12:e86469. [PMID: 37843188 PMCID: PMC10617988 DOI: 10.7554/elife.86469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 10/13/2023] [Indexed: 10/17/2023] Open
Abstract
The role of myelination for axonal conduction is well-established in projection neurons but little is known about its significance in GABAergic interneurons. Myelination is discontinuous along interneuron axons and the mechanisms controlling myelin patterning and segregation of ion channels at the nodes of Ranvier have not been elucidated. Protein 4.1B is implicated in the organization of the nodes of Ranvier as a linker between paranodal and juxtaparanodal membrane proteins to the spectrin cytoskeleton. In the present study, 4.1B KO mice are used as a genetic model to analyze the functional role of myelin in Lhx6-positive parvalbumin (PV) and somatostatin (SST) neurons, two major classes of GABAergic neurons in the hippocampus. We show that 4.1B-deficiency induces disruption of juxtaparanodal K+ channel clustering and mislocalization of nodal or heminodal Na+ channels. Strikingly, 4.1B-deficiency causes loss of myelin in GABAergic axons in the hippocampus. In particular, stratum oriens SST cells display severe axonal dysmyelination and a reduced excitability. This reduced excitability is associated with a decrease in occurrence probability of small amplitude synaptic inhibitory events on pyramidal cells. In contrast, stratum pyramidale fast-spiking PV cells do not appear affected. In conclusion, our results indicate a class-specific effect of dysmyelination on the excitability of hippocampal interneurons associated with a functional alteration of inhibitory drive.
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Affiliation(s)
| | | | | | - Laurence Goutebroze
- INSERM, Institut du Fer à Moulin, Sorbonne Université, Faculté des Sciences et IngénierieParisFrance
| | - Domna Karagogeos
- Department of Basic Sciences, University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, University of CreteHeraklionGreece
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4
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Hashimoto Y, Sadano K, Miyata N, Ito H, Tanaka H. Novel role of DONSON in CMG helicase assembly during vertebrate DNA replication initiation. EMBO J 2023; 42:e114131. [PMID: 37458194 PMCID: PMC10476173 DOI: 10.15252/embj.2023114131] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/27/2023] [Accepted: 06/29/2023] [Indexed: 09/05/2023] Open
Abstract
CMG (Cdc45-MCM-GINS) helicase assembly at the replication origin is the culmination of eukaryotic DNA replication initiation. This process can be reconstructed in vitro using defined factors in Saccharomyces cerevisiae; however, in vertebrates, origin-dependent CMG formation has not yet been achieved partly due to the lack of a complete set of known initiator proteins. Since a microcephaly gene product, DONSON, was reported to remodel the CMG helicase under replication stress, we analyzed its role in DNA replication using a Xenopus cell-free system. We found that DONSON was essential for the replisome assembly. In vertebrates, DONSON physically interacted with GINS and Polε via its conserved N-terminal PGY and NPF motifs, and the DONSON-GINS interaction contributed to the replisome assembly. DONSON's chromatin association during replication initiation required the pre-replicative complex, TopBP1, and kinase activities of S-CDK and DDK. Both S-CDK and DDK required DONSON to trigger replication initiation. Moreover, human DONSON could substitute for the Xenopus protein in a cell-free system. These findings indicate that vertebrate DONSON is a novel initiator protein essential for CMG helicase assembly.
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Affiliation(s)
- Yoshitami Hashimoto
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
| | - Kota Sadano
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
| | - Nene Miyata
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
| | - Haruka Ito
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
| | - Hirofumi Tanaka
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
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Salidroside Alleviates Diabetic Cognitive Dysfunction Via B3galt2/F3/Contactin Signaling Pathway in Mice. Neuroscience 2023; 512:47-58. [PMID: 36509381 DOI: 10.1016/j.neuroscience.2022.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 12/01/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Diabetes is frequently accompanied by cognitive impairment with insidious onset, and progressive cognitive and behavioral changes. β-1, 3-galactosyltransferase 2 (B3galt2) contributes to glycosylation, showing a clue for neuronal apoptosis, proliferation and differentiation. However, the role of B3galt2 in diabetic cognitive dysfunction (DCD) has not been investigated. In the present study, we aimed to explore the role of B3galt2 in DCD. Additionally, the potential therapeutic effects of salidroside on DCD was also explored. Diabetic C57BL/6J mice showed cognitive dysfunction together with down-regulated B3galt2. Overexpression of B3galt2 reversed the cognitive decline of diabetic C57BL/6J. Moreover, cognitive impairment was aggravated in B3galt2+/- diabetic mice compared with C57BL/6J diabetic mice. Immunohistochemistry fluorescence indicated that B3galt2 and F3/Contactin were co-localized in the hippocampal regions. Importantly, the expression of F3/Contactin can be regulated by the manipulation of B3galt2, overexpression of which assuaged hippocampal neuronal damage, protected the synapsin, and reduced neuronal apoptosis in diabetic mice. Interestingly, SAL alleviated DCD and reversed the expression of B3galt2 in diabetic C57BL/6J mice. These findings indicate that inhibition of B3galt2/F3/Contactin pathway contributes to DCD, and participates in SAL reversed DCD.
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6
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Chataigner LMP, Gogou C, den Boer MA, Frias CP, Thies-Weesie DME, Granneman JCM, Heck AJR, Meijer DH, Janssen BJC. Structural insights into the contactin 1 - neurofascin 155 adhesion complex. Nat Commun 2022; 13:6607. [PMID: 36329006 PMCID: PMC9633819 DOI: 10.1038/s41467-022-34302-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/20/2022] [Indexed: 11/06/2022] Open
Abstract
Cell-surface expressed contactin 1 and neurofascin 155 control wiring of the nervous system and interact across cells to form and maintain paranodal myelin-axon junctions. The molecular mechanism of contactin 1 - neurofascin 155 adhesion complex formation is unresolved. Crystallographic structures of complexed and individual contactin 1 and neurofascin 155 binding regions presented here, provide a rich picture of how competing and complementary interfaces, post-translational glycosylation, splice differences and structural plasticity enable formation of diverse adhesion sites. Structural, biophysical, and cell-clustering analysis reveal how conserved Ig1-2 interfaces form competing heterophilic contactin 1 - neurofascin 155 and homophilic neurofascin 155 complexes whereas contactin 1 forms low-affinity clusters through interfaces on Ig3-6. The structures explain how the heterophilic Ig1-Ig4 horseshoe's in the contactin 1 - neurofascin 155 complex define the 7.4 nm paranodal spacing and how the remaining six domains enable bridging of distinct intercellular distances.
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Affiliation(s)
- Lucas M. P. Chataigner
- grid.5477.10000000120346234Structural Biochemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Christos Gogou
- grid.5292.c0000 0001 2097 4740Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Maurits A. den Boer
- grid.5477.10000000120346234Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands ,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Cátia P. Frias
- grid.5292.c0000 0001 2097 4740Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Dominique M. E. Thies-Weesie
- grid.5477.10000000120346234Van’t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute of Nanomaterials Science, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Joke C. M. Granneman
- grid.5477.10000000120346234Structural Biochemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Albert J. R. Heck
- grid.5477.10000000120346234Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands ,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Dimphna H. Meijer
- grid.5292.c0000 0001 2097 4740Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Bert J. C. Janssen
- grid.5477.10000000120346234Structural Biochemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
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7
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Pascual-Goñi E, Fehmi J, Lleixà C, Martín-Aguilar L, Devaux J, Höftberger R, Delmont E, Doppler K, Sommer C, Radunovic A, Carvajal A, Smyth S, Williams L, Mazanec R, Potočková V, Hinds N, Cassereau J, Viala K, Lefilliatre M, Nicolas G, Foley P, Leypoldt F, Keddie S, Lunn MP, Zimprich F, Nunkoo VS, Löscher WN, Martínez-Martínez L, Díaz-Manera J, Rojas-Garcia R, Illa I, Rinaldi S, Querol L. Antibodies to the Caspr1/contactin-1 complex in chronic inflammatory demyelinating polyradiculoneuropathy. Brain 2021; 144:1183-1196. [PMID: 33880507 DOI: 10.1093/brain/awab014] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 10/02/2020] [Accepted: 11/04/2020] [Indexed: 12/19/2022] Open
Abstract
Previous studies have described the clinical, serological and pathological features of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and antibodies directed against the paranodal proteins neurofascin-155, contactin-1 (CNTN1), contactin-associated protein-1 (Caspr1), or nodal forms of neurofascin. Such antibodies are useful for diagnosis and potentially treatment selection. However, antibodies targeting Caspr1 only or the Caspr1/CNTN1 complex have been reported in few patients with CIDP. Moreover, it is unclear if these patients belong to the same pathophysiological subgroup. Using cell-based assays in routine clinical testing, we identified sera from patients with CIDP showing strong membrane reactivity when both CNTN1 and Caspr1 were co-transfected (but not when CNTN1 was transfected alone). Fifteen patients (10 male; aged between 40 and 75) with antibodies targeting Caspr1/CNTN1 co-transfected cells were enrolled for characterization. The prevalence of anti-Caspr1/CNTN1 antibodies was 1.9% (1/52) in the Sant Pau CIDP cohort, and 4.3% (1/23) in a German cohort of acute-onset CIDP. All patients fulfilled European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) definite diagnostic criteria for CIDP. Seven (47%) were initially diagnosed with Guillain-Barré syndrome due to an acute-subacute onset. Six (40%) patients had cranial nerve involvement, eight (53%) reported neuropathic pain and 12 (80%) ataxia. Axonal involvement and acute denervation were frequent in electrophysiological studies. Complete response to intravenous immunoglobulin was not observed, while most (90%) responded well to rituximab. Enzyme-linked immunosorbent assay (ELISA) and teased nerve fibre immunohistochemistry confirmed reactivity against the paranodal Caspr1/CNTN1 complex. Weaker reactivity against Caspr1 transfected alone was also detected in 10/15 (67%). Sera from 13 of these patients were available for testing by ELISA. All 13 samples reacted against Caspr1 by ELISA and this reactivity was enhanced when CNTN1 was added to the Caspr1 ELISA. IgG subclasses were also investigated by ELISA. IgG4 was the predominant subclass in 10 patients, while IgG3 was predominant in other three patients. In conclusion, patients with antibodies to the Caspr1/CNTN1 complex display similar serological and clinical features and constitute a single subgroup within the CIDP syndrome. These antibodies likely target Caspr1 primarily and are detected with Caspr1-only ELISA, but reactivity is optimal when CNTN1 is added to Caspr1 in cell-based assays and ELISA.
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Affiliation(s)
- Elba Pascual-Goñi
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain
| | - Janev Fehmi
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Cinta Lleixà
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain
| | - Lorena Martín-Aguilar
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain
| | - Jérôme Devaux
- Institut de Neurosciences de Montpellier, Hospital Saint Eloi, Montpelier, France
| | - Romana Höftberger
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Emilien Delmont
- Referral Centre for ALS and Neuromuscular Diseases, Hospital La Timone, Marseille, France
| | - Kathrin Doppler
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Claudia Sommer
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | | | | | - Shane Smyth
- Mater Misericordiae University Hospital, Dublin, Republic of Ireland
| | - Laura Williams
- Mater Misericordiae University Hospital, Dublin, Republic of Ireland
| | - Radim Mazanec
- Department of Neurology, Medical Faculty of Charles University and University Hospital Motol, Prague, Czech Republic
| | - Veronika Potočková
- Department of Neurology, Medical Faculty of Charles University and University Hospital Motol, Prague, Czech Republic
| | - Nigel Hinds
- Abertawe Bro Morgannwg University Health Board, Swansea, Wales, UK
| | - Julien Cassereau
- Reference Centre for Neuromuscular Diseases, Department of Neurology, Angers University Hospital, Angers, France
| | - Karine Viala
- Department of Clinical Neurophysiology, Hospital de la Pitié-Salpêtrière. Paris, France
| | | | - Guillaume Nicolas
- Department of Neurology, Hôpital Raymond-Poincaré, Université Versailles-Saint-Quentin-en-Yvelines, Garches, France
| | - Peter Foley
- Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh, UK
| | - Frank Leypoldt
- Institute of Clinical Chemistry, University Hospital Schleswig-Holstein, Kiel, Germany.,Department of Neurology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Stephen Keddie
- Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Michael P Lunn
- Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Fritz Zimprich
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Vharoon Sharma Nunkoo
- Department of Neurology, Municipal University Hospital Dr. Gavril Curteanu, Oradea, Romania
| | | | - Laura Martínez-Martínez
- Department of Immunology, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Jordi Díaz-Manera
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain.,Centro para la Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Spain
| | - Ricard Rojas-Garcia
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain.,Centro para la Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Spain
| | - Isabel Illa
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain.,Centro para la Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Spain
| | - Simon Rinaldi
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Luis Querol
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain.,Centro para la Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Spain
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8
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Chataigner LMP, Leloup N, Janssen BJC. Structural Perspectives on Extracellular Recognition and Conformational Changes of Several Type-I Transmembrane Receptors. Front Mol Biosci 2020; 7:129. [PMID: 32850948 PMCID: PMC7427315 DOI: 10.3389/fmolb.2020.00129] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 06/02/2020] [Indexed: 12/19/2022] Open
Abstract
Type-I transmembrane proteins represent a large group of 1,412 proteins in humans with a multitude of functions in cells and tissues. They are characterized by an extracellular, or luminal, N-terminus followed by a single transmembrane helix and a cytosolic C-terminus. The domain composition and structures of the extracellular and intercellular segments differ substantially amongst its members. Most of the type-I transmembrane proteins have roles in cell signaling processes, as ligands or receptors, and in cellular adhesion. The extracellular segment often determines specificity and can control signaling and adhesion. Here we focus on recent structural understanding on how the extracellular segments of several diverse type-I transmembrane proteins engage in interactions and can undergo conformational changes for their function. Interactions at the extracellular side by proteins on the same cell or between cells are enhanced by the transmembrane setting. Extracellular conformational domain rearrangement and structural changes within domains alter the properties of the proteins and are used to regulate signaling events. The combination of structural properties and interactions can support the formation of larger-order assemblies on the membrane surface that are important for cellular adhesion and intercellular signaling.
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Affiliation(s)
- Lucas M. P. Chataigner
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Nadia Leloup
- Structural Biology and Protein Biochemistry, Morphic Therapeutic, Waltham, MA, United States
| | - Bert J. C. Janssen
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Utrecht, Netherlands
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9
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Molecular organization and function of vertebrate septate-like junctions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183211. [PMID: 32032590 DOI: 10.1016/j.bbamem.2020.183211] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/22/2020] [Accepted: 01/26/2020] [Indexed: 12/21/2022]
Abstract
Septate-like junctions display characteristic ladder-like ultrastructure reminiscent of the invertebrate epithelial septate junctions and are present at the paranodes of myelinated axons. The paranodal junctions where the myelin loops attach to the axon at the borders of the node of Ranvier provide both a paracellular barrier to ion diffusion and a lateral fence along the axonal membrane. The septate-like junctions constrain the proper distribution of nodal Na+ channels and juxtaparanodal K+ channels, which are required for the safe propagation of the nerve influx and rapid saltatory conduction. The paranodal cell adhesion molecules have been identified as target antigens in peripheral demyelinating autoimmune diseases and the pathogenic mechanisms described. This review aims at presenting the recent knowledge on the molecular and structural organization of septate-like junctions, their formation and stabilization during development, and how they are involved in demyelinating diseases.
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10
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Kjaergaard M, Kragelund BB. Functions of intrinsic disorder in transmembrane proteins. Cell Mol Life Sci 2017; 74:3205-3224. [PMID: 28601983 PMCID: PMC11107515 DOI: 10.1007/s00018-017-2562-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 06/01/2017] [Indexed: 12/19/2022]
Abstract
Intrinsic disorder is common in integral membrane proteins, particularly in the intracellular domains. Despite this observation, these domains are not always recognized as being disordered. In this review, we will discuss the biological functions of intrinsically disordered regions of membrane proteins, and address why the flexibility afforded by disorder is mechanistically important. Intrinsically disordered regions are present in many common classes of membrane proteins including ion channels and transporters; G-protein coupled receptors (GPCRs), receptor tyrosine kinases and cytokine receptors. The functions of the disordered regions are many and varied. We will discuss selected examples including: (1) Organization of receptors, kinases, phosphatases and second messenger sources into signaling complexes. (2) Modulation of the membrane-embedded domain function by ball-and-chain like mechanisms. (3) Trafficking of membrane proteins. (4) Transient membrane associations. (5) Post-translational modifications most notably phosphorylation and (6) disorder-linked isoform dependent function. We finish the review by discussing the future challenges facing the membrane protein community regarding protein disorder.
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Affiliation(s)
- Magnus Kjaergaard
- Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus, Denmark.
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark.
- The Danish Research Institute of Translational Neuroscience (DANDRITE), Aarhus, Denmark.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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11
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Autoantibodies in chronic inflammatory neuropathies: diagnostic and therapeutic implications. Nat Rev Neurol 2017; 13:533-547. [PMID: 28708133 DOI: 10.1038/nrneurol.2017.84] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The chronic inflammatory neuropathies (CINs) are rare, very disabling autoimmune disorders that generally respond well to immune therapies such as intravenous immunoglobulin (IVIg). The most common forms of CIN are chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy, and polyneuropathy associated with monoclonal gammopathy of unknown significance. The field of CIN has undergone a major advance with the identification of IgG4 autoantibodies directed against paranodal proteins in patients with CIDP. Although these autoantibodies are only found in a small subset of patients with CIDP, they can be used to guide therapeutic decision-making, as these patients have a poor response to IVIg. These observations provide proof of concept that identifying the target antigens in tissue-specific antibody-mediated autoimmune diseases is important, not only to understand their underlying pathogenic mechanisms, but also to correctly diagnose and treat affected patients. This state-of-the-art Review focuses on the role of autoantibodies against nodes of Ranvier in CIDP, a clinically relevant emerging field of research. The role of autoantibodies in other immune-mediated neuropathies, including other forms of CIN, primary autoimmune neuropathies, neoplasms, and systemic diseases that resemble CIN, are also discussed.
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12
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Axonal transport deficits in multiple sclerosis: spiraling into the abyss. Acta Neuropathol 2017; 134:1-14. [PMID: 28315956 PMCID: PMC5486629 DOI: 10.1007/s00401-017-1697-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 12/16/2022]
Abstract
The transport of mitochondria and other cellular components along the axonal microtubule cytoskeleton plays an essential role in neuronal survival. Defects in this system have been linked to a large number of neurological disorders. In multiple sclerosis (MS) and associated models such as experimental autoimmune encephalomyelitis (EAE), alterations in axonal transport have been shown to exist before neurodegeneration occurs. Genome-wide association (GWA) studies have linked several motor proteins to MS susceptibility, while neuropathological studies have shown accumulations of proteins and organelles suggestive for transport deficits. A reduced effectiveness of axonal transport can lead to neurodegeneration through inhibition of mitochondrial motility, disruption of axoglial interaction or prevention of remyelination. In MS, demyelination leads to dysregulation of axonal transport, aggravated by the effects of TNF-alpha, nitric oxide and glutamate on the cytoskeleton. The combined effect of all these pathways is a vicious cycle in which a defective axonal transport system leads to an increase in ATP consumption through loss of membrane organization and a reduction in available ATP through inhibition of mitochondrial transport, resulting in even further inhibition of transport. The persistent activity of this positive feedback loop contributes to neurodegeneration in MS.
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Zou Y, Zhang WF, Liu HY, Li X, Zhang X, Ma XF, Sun Y, Jiang SY, Ma QH, Xu DE. Structure and function of the contactin-associated protein family in myelinated axons and their relationship with nerve diseases. Neural Regen Res 2017; 12:1551-1558. [PMID: 29090003 PMCID: PMC5649478 DOI: 10.4103/1673-5374.215268] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The contactin-associated protein (Caspr) family participates in nerve excitation and conduction, and neurotransmitter release in myelinated axons. We analyzed the structures and functions of the Caspr family–CNTNAP1 (Caspr1), CNTNAP2 (Caspr2), CNTNAP3 (Caspr3), CNTNAP4 (Caspr4) and CNTNAP5 (Caspr5), Caspr1–5 is not only involved in the formation of myelinated axons, but also participates in maintaining the stability of adjacent connections. Caspr1 participates in the formation, differentiation, and proliferation of neurons and astrocytes, and in motor control and cognitive function. We also analyzed the relationship between the Caspr family and neurodegenerative diseases, multiple sclerosis, and autoimmune encephalitis. However, the effects of Caspr on disease course and prognosis remain poorly understood. The effects of Caspr on disease diagnosis and treatment need further investigation.
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Affiliation(s)
- Yan Zou
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
| | - Wei-Feng Zhang
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
| | - Hai-Ying Liu
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
| | - Xia Li
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
| | - Xing Zhang
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
| | - Xiao-Fang Ma
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
| | - Yang Sun
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
| | - Shi-Yi Jiang
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
| | - Quan-Hong Ma
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
| | - De-En Xu
- Department of Neurology, The Second People's Hospital of Wuxi, Wuxi, Jiangsu Province, China
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14
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Palavicini JP, Wang C, Chen L, Ahmar S, Higuera JD, Dupree JL, Han X. Novel molecular insights into the critical role of sulfatide in myelin maintenance/function. J Neurochem 2016; 139:40-54. [PMID: 27417284 DOI: 10.1111/jnc.13738] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 06/17/2016] [Accepted: 06/22/2016] [Indexed: 01/19/2023]
Abstract
Cerebroside sulfotransferase (CST) catalyzes the production of sulfatide, a major class of myelin-specific lipids. CST knockout (CST(-/-) ) mice in which sulfatide is completely depleted are born healthy, but display myelin abnormalities and progressive tremors starting at 4-6 weeks of age. Although these phenotypes suggest that sulfatide plays a critical role in myelin maintenance/function, the underlying mechanisms remain largely unknown. We analyzed the major CNS myelin proteins and the major lipids enriched in the myelin in a spatiotemporal manner. We found a one-third reduction of the major compact myelin proteins (myelin basic protein, myelin basic protein, and proteolipid protein, PLP) and an equivalent post-developmental loss of myelin lipids, providing the molecular basis behind the thinner myelin sheaths. Our lipidomics data demonstrated that the observed global reduction of myelin lipid content was not because of an increase of lipid degradation but rather to the reduction of their synthesis by oligodendrocytes. We also showed that sulfatide depletion leads to region-specific effects on non-compact myelin, dramatically affecting the paranode (neurofascin 155) and the major inner tongue myelin protein (myelin-associated glycoprotein). Moreover, we demonstrated that sulfatide promotes the interaction between adjacent PLP extracellular domains, evidenced by a progressive decline of high molecular weight PLP complexes in CST(-/-) mice, providing an explanation at a molecular level regarding the uncompacted myelin sheaths. Finally, we proposed that the dramatic losses of neurofascin 155 and PLP interactions are responsible for the progressive tremors and eventual ataxia. In summary, we unraveled novel molecular insights into the critical role of sulfatide in myelin maintenance/function. Cerebroside sulfotransferase (CST) catalyzes the production of sulfatide, a major class of myelin-specific lipids. CST knockout (CST(-/-) ) mice in which sulfatide is completely depleted are born healthy, but display myelin abnormalities We show in our study that sulfatide depletion leads to losses of myelin proteins and lipids, and impairment of myelin functions, unraveling novel molecular insights into the critical role of sulfatide in myelin maintenance/function.
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Affiliation(s)
- Juan Pablo Palavicini
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Chunyan Wang
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Linyuan Chen
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Sareen Ahmar
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Juan Diego Higuera
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Jeffrey L Dupree
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA.,Research Division, McGuire Veterans Affairs Medical Center, Richmond, Virginia, USA
| | - Xianlin Han
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA.
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15
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Hivert B, Pinatel D, Labasque M, Tricaud N, Goutebroze L, Faivre-Sarrailh C. Assembly of juxtaparanodes in myelinating DRG culture: Differential clustering of the Kv1/Caspr2 complex and scaffolding protein 4.1B. Glia 2016; 64:840-52. [PMID: 26840208 DOI: 10.1002/glia.22968] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 01/04/2016] [Accepted: 01/06/2016] [Indexed: 11/06/2022]
Abstract
The precise distribution of ion channels at the nodes of Ranvier is essential for the efficient propagation of action potentials along myelinated axons. The voltage-gated potassium channels Kv1.1/1.2 are clustered at the juxtaparanodes in association with the cell adhesion molecules, Caspr2 and TAG-1 and the scaffolding protein 4.1B. In the present study, we set up myelinating cultures of DRG neurons and Schwann cells to look through the formation of juxtaparanodes in vitro. We showed that the Kv1.1/Kv1.2 channels were first enriched at paranodes before being restricted to distal paranodes and juxtaparanodes. In addition, the Kv1 channels displayed an asymmetric expression enriched at the distal juxtaparanodes. Caspr2 was strongly co-localized with Kv1.2 whereas the scaffolding protein 4.1B was preferentially recruited at paranodes while being present at juxtaparanodes too. Kv1.2/Caspr2 but not 4.1B, also transiently accumulated within the nodal region both in myelinated cultures and developing sciatic nerves. Studying cultures and sciatic nerves from 4.1B KO mice, we further showed that 4.1B is required for the proper targeting of Caspr2 early during myelination. Moreover, using adenoviral-mediated expression of Caspr-GFP and photobleaching experiments, we analyzed the stability of paranodal junctions and showed that the lateral stability of paranodal Caspr was not altered in 4.1B KO mice indicating that 4.1B is not required for the assembly and stability of the paranodal junctions. Thus, developing an adapted culture paradigm, we provide new insights into the dynamic and differential distribution of Kv1 channels and associated proteins during myelination.
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Affiliation(s)
- Bruno Hivert
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille-UMR7286, Marseille, France
| | - Delphine Pinatel
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille-UMR7286, Marseille, France
| | - Marilyne Labasque
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille-UMR7286, Marseille, France
| | - Nicolas Tricaud
- INSERM U1051 Institut des Neurosciences de Montpellier, Montpellier, France
| | | | - Catherine Faivre-Sarrailh
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille-UMR7286, Marseille, France
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16
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Ma Y, Li J, Yu H, Wang L, Lu T, Pan C, Han Y, Zhang D, Yue W. Association of chromosome 5q21.3 polymorphisms with the exploratory eye movement dysfunction in schizophrenia. Sci Rep 2015; 5:10299. [PMID: 26242244 PMCID: PMC4533163 DOI: 10.1038/srep10299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/07/2015] [Indexed: 11/09/2022] Open
Abstract
Schizophrenia patients show abnormalities in many eye movement tasks. Among them, exploratory eye movements (EEM) dysfunction seems to be specific to schizophrenia. However the mechanism of EEM disturbances in schizophrenia patients remains elusive. We investigate the relationship between EEM and single nucleotide polymorphisms (SNPs) or genes to identify susceptibility loci for EEM in schizophrenia. We firstly performed EEM test, then performed a genome-wide association study (GWAS) and gene-based association study of EEM in 128 individuals with schizophrenia and 143 healthy control subjects. Comparing to healthy controls, schizophrenia patients show significant decrease in NEF (22.99 ± 3.96 vs. 26.02 ± 5.72, P <0.001), TESL (368.78 ± 123.57 vs. 603.12 ± 178.63, P <0.001), MESL (16.86 ± 5.27 vs. 24.42 ± 6.46, P <0.001), RSS (8.22 ± 1.56 vs. 10.92 ± 1.09, P <0.001), and CSS (5.06 ± 0.97 vs. 6.64 ± 0.87, P <0.001). Five SNPs of the MAN2A1, at 5q21.3, were associated with EEM abnormalities (deceased CSS) and satisfied the criteria of GWAS significance threshold. One is localized near 5'-UTR (rs17450784) and four are in intron (rs1438663, rs17162094, rs6877440 and rs10067856) of the gene. Our findings suggest that the identified loci may control the schizophrenia-related quantitative EEM trait. And the identified gene, associated with the EEM phenotype, may lead to new insights into the etiology of schizophrenia.
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Affiliation(s)
- Yuanlin Ma
- 1] Institute of Mental Health, The Sixth Hospital, Peking University, Beijing 100191, China [2] Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China
| | - Jun Li
- 1] Institute of Mental Health, The Sixth Hospital, Peking University, Beijing 100191, China [2] Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China
| | - Hao Yu
- 1] Institute of Mental Health, The Sixth Hospital, Peking University, Beijing 100191, China [2] Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China [3] School of Life Sciences, Tsinghua University, Beijing 100084, China [4] Peking University-Tsinghua University Joint Center for Life Sciences, Beijing 100871, China
| | - Lifang Wang
- 1] Institute of Mental Health, The Sixth Hospital, Peking University, Beijing 100191, China [2] Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China
| | - Tianlan Lu
- 1] Institute of Mental Health, The Sixth Hospital, Peking University, Beijing 100191, China [2] Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China
| | - Chao Pan
- 1] Institute of Mental Health, The Sixth Hospital, Peking University, Beijing 100191, China [2] Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China
| | - Yonghua Han
- 1] Institute of Mental Health, The Sixth Hospital, Peking University, Beijing 100191, China [2] Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China
| | - Dai Zhang
- 1] Institute of Mental Health, The Sixth Hospital, Peking University, Beijing 100191, China [2] Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China [3] School of Life Sciences, Tsinghua University, Beijing 100084, China [4] Peking University-Tsinghua University Joint Center for Life Sciences, Beijing 100871, China [5] PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
| | - Weihua Yue
- 1] Institute of Mental Health, The Sixth Hospital, Peking University, Beijing 100191, China [2] Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China
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17
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Abad-Rodríguez J, Díez-Revuelta N. Axon glycoprotein routing in nerve polarity, function, and repair. Trends Biochem Sci 2015; 40:385-96. [PMID: 25936977 DOI: 10.1016/j.tibs.2015.03.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 03/13/2015] [Accepted: 03/31/2015] [Indexed: 02/04/2023]
Abstract
Nervous system function relies on the capacity of neurons to organize specialized domains for impulse reception or transmission. Such a polarized architecture relies on highly discriminatory and efficient mechanisms for the transport and targeting of required molecules to their functional positions. Glycans play a central role in polarized traffic based on their extraordinary capacity to encrypt bio-information. Glycan-based interactions exquisitely regulate cargo selection, trafficking, and targeting to the axon membrane. This generates segregated functional domains, where basal nerve processes such as axon growth, synaptic activity, or myelination take place. Deciphering the details of the glycan structures and carbohydrate-binding molecules that underlie these mechanisms improves our knowledge of nerve physiology and defines novel specific approaches for neurological treatments.
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Affiliation(s)
- José Abad-Rodríguez
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Finca La Peraleda s/n, 45071 Toledo, Spain.
| | - Natalia Díez-Revuelta
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Finca La Peraleda s/n, 45071 Toledo, Spain
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18
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Devaux JJ. [New insights on the organization of the nodes of Ranvier]. Rev Neurol (Paris) 2014; 170:819-24. [PMID: 25459119 DOI: 10.1016/j.neurol.2014.03.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 03/05/2014] [Indexed: 01/06/2023]
Abstract
Myelin plays a crucial role in the rapid and saltatory conduction of the nerve impulse along myelinated axons. In addition, myelin closely regulates the organization of the axonal compartments. This organization involves several complex mechanisms including axo-glial contact, diffusion barriers, the cytoskeletal network, and the extracellular matrix. In peripheral nerves, the axo-glial contact dictates the formation of the nodes and the clustering of the voltage-gated sodium channels (Nav). The axo-glial contact at nodes implicates adhesion molecules expressed by the Schwann cell (gliomedin and NrCAM), which binds a partner, neurofascin-186, on the axonal side. This complex is essential for the recruitment of ankyrin-G, a cytoskeletal scaffolding protein, which binds and concentrates Nav channels at nodes. The paranodal junctions flanking the nodes also play a complementary function in node formation. These junctions are formed by the association of contactin-1/caspr-1/neurofascin-155 and create a diffusion barrier, which traps proteins at the nodes and dampens their diffusion along the internode. In the central nervous system, the mechanisms of node formation are different and the formation of the paranodal junctions precedes the aggregation of Nav channels at nodes. However, node formation can still happen in absence of paranodal junctions in the CNS. One explanation is that NF186 interacts with components of the extracellular matrix around the node and thereby stabilizes the aggregation of nodal proteins. It is likely that many other proteins are also implicated in the signaling pathways that regulate the differentiation of the axonal compartments. The nature and function of these proteins are yet to be identified.
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Affiliation(s)
- J J Devaux
- Centre de recherche en neurobiologie et neurophysiologie de Marseille, faculté de médecine secteur Nord, Aix-Marseille université, CNRS-UMR7286, 51, boulevard Pierre-Dramard, CS80011, 13344 Marseille cedex 15, France.
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19
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Ganot P, Zoccola D, Tambutté E, Voolstra CR, Aranda M, Allemand D, Tambutté S. Structural molecular components of septate junctions in cnidarians point to the origin of epithelial junctions in eukaryotes. Mol Biol Evol 2014; 32:44-62. [PMID: 25246700 DOI: 10.1093/molbev/msu265] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Septate junctions (SJs) insure barrier properties and control paracellular diffusion of solutes across epithelia in invertebrates. However, the origin and evolution of their molecular constituents in Metazoa have not been firmly established. Here, we investigated the genomes of early branching metazoan representatives to reconstruct the phylogeny of the molecular components of SJs. Although Claudins and SJ cytoplasmic adaptor components appeared successively throughout metazoan evolution, the structural components of SJs arose at the time of Placozoa/Cnidaria/Bilateria radiation. We also show that in the scleractinian coral Stylophora pistillata, the structural SJ component Neurexin IV colocalizes with the cortical actin network at the apical border of the cells, at the place of SJs. We propose a model for SJ components in Cnidaria. Moreover, our study reveals an unanticipated diversity of SJ structural component variants in cnidarians. This diversity correlates with gene-specific expression in calcifying and noncalcifying tissues, suggesting specific paracellular pathways across the cell layers of these diploblastic animals.
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Affiliation(s)
- Philippe Ganot
- Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco
| | - Didier Zoccola
- Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco
| | - Eric Tambutté
- Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco
| | - Christian R Voolstra
- Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Manuel Aranda
- Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Denis Allemand
- Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco
| | - Sylvie Tambutté
- Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco
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Progressive disorganization of paranodal junctions and compact myelin due to loss of DCC expression by oligodendrocytes. J Neurosci 2014; 34:9768-78. [PMID: 25031414 DOI: 10.1523/jneurosci.0448-14.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Paranodal axoglial junctions are critical for maintaining the segregation of axonal domains along myelinated axons; however, the proteins required to organize and maintain this structure are not fully understood. Netrin-1 and its receptor Deleted in Colorectal Cancer (DCC) are proteins enriched at paranodes that are expressed by neurons and oligodendrocytes. To identify the specific function of DCC expressed by oligodendrocytes in vivo, we selectively eliminated DCC from mature myelinating oligodendrocytes using an inducible cre regulated by the proteolipid protein promoter. We demonstrate that DCC deletion results in progressive disruption of the organization of axonal domains, myelin ultrastructure, and myelin protein composition. Conditional DCC knock-out mice develop balance and coordination deficits and exhibit decreased conduction velocity. We conclude that DCC expression by oligodendrocytes is required for the maintenance and stability of myelin in vivo, which is essential for proper signal conduction in the CNS.
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21
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Labasque M, Hivert B, Nogales-Gadea G, Querol L, Illa I, Faivre-Sarrailh C. Specific contactin N-glycans are implicated in neurofascin binding and autoimmune targeting in peripheral neuropathies. J Biol Chem 2014; 289:7907-18. [PMID: 24497634 DOI: 10.1074/jbc.m113.528489] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Cell adhesion molecules (CAMs) play a crucial role in the formation of the nodes of Ranvier and in the rapid propagation of the nerve impulses along myelinated axons. These CAMs are the targets of autoimmunity in inflammatory neuropathies. We recently showed that a subgroup of patients with aggressive chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) shows autoantibodies to contactin (1). The complex of contactin·Caspr·neurofascin-155 (NF155) enables the formation of paranodal junctions, suggesting that antibody attack against paranodes may participate in the severity of CIDP. In the present study, we mapped the molecular determinants of contactin targeted by the autoantibodies. In three patients, immunoreactivity was directed against the Ig domains of contactin and was dependent on N-glycans. The serum of one patient was selectively directed against contactin bearing mannose-rich N-glycans. Strikingly, the oligomannose type sugars of contactin are required for association with its glial partner NF155 (2). To investigate precisely the role of contactin N-glycans, we have mutated each of the nine consensus N-glycosylation sites independently. We found that the mutation of three sites (N467Q/N473Q/N494Q) in Ig domain 5 of contactin prevented soluble NF155-Fc binding. In contrast, these mutations did not abolish cis-association with Caspr. Next, we showed that the cluster of N-glycosylation sites (Asn-467, Asn-473, and Asn-494) was required for immunoreactivity in one patient. Using cell aggregation assays, we showed that the IgGs from the four CIDP patients prevented adhesive interaction between contactin·Caspr and NF155. Importantly, we showed that the anti-contactin autoantibodies induced alteration of paranodal junctions in myelinated neuronal culture. These results strongly suggest that antibodies to CAMs may be pathogenic and induce demyelination via functional blocking activity.
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Affiliation(s)
- Marilyne Labasque
- From Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille-UMR7286, 13344 Marseille, France
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Faivre-Sarrailh C, Devaux JJ. Neuro-glial interactions at the nodes of Ranvier: implication in health and diseases. Front Cell Neurosci 2013; 7:196. [PMID: 24194699 PMCID: PMC3810605 DOI: 10.3389/fncel.2013.00196] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 10/08/2013] [Indexed: 01/06/2023] Open
Abstract
Specific cell adhesion molecules (CAMs) are dedicated to the formation of axo-glial contacts at the nodes of Ranvier of myelinated axons. They play a central role in the organization and maintenance of the axonal domains: the node, paranode, and juxtaparanode. In particular, CAMs are essential for the accumulation of voltage-gated sodium channels at the nodal gap that ensures the rapid and saltatory propagation of the action potentials (APs). The mechanisms regulating node formation are distinct in the central and peripheral nervous systems, and recent studies have highlighted the relative contribution of paranodal junctions and nodal extracellular matrix. In addition, CAMs at the juxtaparanodal domains mediate the clustering of voltage-gated potassium channels which regulate the axonal excitability. In several human pathologies, the axo-glial contacts are altered leading to disruption of the nodes of Ranvier or mis-localization of the ion channels along the axons. Node alterations and the failure of APs to propagate correctly from nodes to nodes along the axons both contribute to the disabilities in demyelinating diseases. This article reviews the mechanisms regulating the association of the axo-glial complexes and the role of CAMs in inherited and acquired neurological diseases.
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23
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Pomicter AD, Deloyht JM, Hackett AR, Purdie N, Sato-Bigbee C, Henderson SC, Dupree JL. Nfasc155H and MAG are specifically susceptible to detergent extraction in the absence of the myelin sphingolipid sulfatide. Neurochem Res 2013; 38:2490-502. [PMID: 24081651 DOI: 10.1007/s11064-013-1162-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 07/17/2013] [Accepted: 09/20/2013] [Indexed: 12/13/2022]
Abstract
Mice incapable of synthesizing the myelin lipid sulfatide form paranodes that deteriorate with age. Similar instability also occurs in mice that lack contactin, contactin-associated protein or neurofascin155 (Nfasc155), the proteins that cluster in the paranode and form the junctional complex that mediates myelin-axon adhesion. In contrast to these proteins, sulfatide has not been shown to be enriched in the paranode nor has a sulfatide paranodal binding partner been identified; thus, it remains unclear how the absence of sulfatide results in compromised paranode integrity. Using an in situ extraction procedure, it has been reported that the absence of the myelin sphingolipids, galactocerebroside and sulfatide, increased the susceptibility of Nfasc155 to detergent extraction. Here, employing a similar approach, we demonstrate that in the presence of galactocerebroside but in the absence of sulfatide Nfasc155 is susceptible to detergent extraction. Furthermore, we use this in situ approach to show that stable association of myelin-associated glycoprotein (MAG) with the myelin membrane is sulfatide dependent while the membrane associations of myelin/oligodendrocyte glycoprotein, myelin basic protein and cyclic nucleotide phosphodiesterase are sulfatide independent. These findings indicate that myelin proteins maintain their membrane associations by different mechanisms. Moreover, the myelin proteins that cluster in the paranode and require sulfatide mediate myelin-axon adhesion. Additionally, the apparent dependency on sulfatide for maintaining Nfasc155 and MAG associations is intriguing since the fatty acid composition of sulfatide is altered and paranodal ultrastructure is compromised in multiple sclerosis. Thus, our findings present a potential link between sulfatide perturbation and myelin deterioration in multiple sclerosis.
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Affiliation(s)
- A D Pomicter
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, 1101 E. Marshall Street, Richmond, VA, 23298, USA
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Shepherd MN, Pomicter AD, Velazco CS, Henderson SC, Dupree JL. Paranodal reorganization results in the depletion of transverse bands in the aged central nervous system. Neurobiol Aging 2012; 33:203.e13-24. [PMID: 20888080 PMCID: PMC3282488 DOI: 10.1016/j.neurobiolaging.2010.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 07/26/2010] [Accepted: 08/05/2010] [Indexed: 11/16/2022]
Abstract
Paranodal axo-glial junctional complexes anchor the myelin sheath to the axon and breakdown of these complexes presumably facilitates demyelination. Myelin deterioration is also prominent in the aging central nervous system (CNS); however, the stability of the paranodal complexes in the aged CNS has not been examined. Here, we show that transverse bands, prominent components of paranodal junctions, are significantly reduced in the aged CNS; however, the number of paired clusters of both myelin and axonal paranodal proteins is not altered. Ultrastructural analyses also reveal that thicker myelin sheaths display a "piling" of paranodal loops, the cytoplasm-containing sacs that demarcate the paranode. Loops involved in piling are observed throughout the paranode and are not limited to loops positioned in either the nodal- or juxtanodal-most regions. Here, we propose that as myelination continues, previously anchored loops lose their transverse bands and recede away from the axolemma. Newly juxtaposed loops then lose their transverse bands, move laterally to fill in the gap left by the receded loops and finally reform their transverse bands. This paranodal reorganization results in conservation of paranodal length, which may be important in maintaining ion channel spacing and axonal function. Furthermore, we propose that transverse band reformation is less efficient in the aged CNS, resulting in the significant reduction of these junctional components. Although demyelination was not observed, we propose that loss of transverse bands facilitates myelin degeneration and may predispose the aged CNS to a poorer prognosis following a secondary insult.
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Affiliation(s)
- Mark N. Shepherd
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, USA 23298
- MD Biosciences, 2575 University Avenue W. Suite 100 St Paul, MN, USA 55114 (present address)
| | - Anthony D. Pomicter
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, USA 23298
| | - Cristine S. Velazco
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, USA 23298
| | - Scott C. Henderson
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, USA 23298
| | - Jeffrey L. Dupree
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, USA 23298
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Labasque M, Devaux JJ, Lévêque C, Faivre-Sarrailh C. Fibronectin type III-like domains of neurofascin-186 protein mediate gliomedin binding and its clustering at the developing nodes of Ranvier. J Biol Chem 2011; 286:42426-42434. [PMID: 22009740 DOI: 10.1074/jbc.m111.266353] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The cell adhesion molecules (CAMs) of the immunoglobulin superfamily (Ig-CAMs) play a crucial role in the organization of the node of Ranvier in myelinated axons. In the peripheral nervous system, Gliomedin (Gldn) secreted by Schwann cell microvilli binds NgCAM-related CAM (NrCAM) and Neurofascin-186 (NF186) and direct the nodal clustering of voltage-gated sodium channels (Nav). NF186 is the single axonal Gldn partner to ensure Nav clustering at nodes, whereas NrCAM is only required in glial cells (Feinberg, K., Eshed-Eisenbach, Y., Frechter, S., Amor, V., Salomon, D., Sabanay, H., Dupree, J. L., Grumet, M., Brophy, P. J., Shrager, P., and Peles, E. (2010) Neuron 65, 490-502). The olfactomedin domain of Gldn is implicated in the interaction with nodal Ig-CAMs. However, the interacting modules of NrCAM or NF186 involved in Gldn association are unknown. Here, we report that fibronectin type III-like (FnIII) domains of both Ig-CAMs mediate their interaction with Gldn in pulldown and cell binding assays. Using surface plasmon resonance assays, we determined that NrCAM and NF186 display similar affinity constant for their association with Gldn (K(D) of 0.9 and 5.7 nm, respectively). We characterized the FnIII domains 1 and 2 of NF186 as interacting modules that ensure association with Gldn. We found that the soluble FnIII domains of NF186 (FnIII-Fc) bind on Schwann cells and inhibit Gldn and Nav clustering at heminodes, the precursors of mature nodes in myelinating cultures. Our study reveals the unexpected importance of FnIII domains of Ig-CAMs in the organization of nodes of Ranvier in peripheral axons. Thus, NF186 utilizes distinct modules to organize the multimeric nodal complex.
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Affiliation(s)
- Marilyne Labasque
- Aix-Marseille Université, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, 13344 Marseille, France; CNRS UMR 6231, 13344 Marseille, France
| | - Jérôme J Devaux
- Aix-Marseille Université, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, 13344 Marseille, France; CNRS UMR 6231, 13344 Marseille, France
| | | | - Catherine Faivre-Sarrailh
- Aix-Marseille Université, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, 13344 Marseille, France; CNRS UMR 6231, 13344 Marseille, France.
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A Laminin G-EGF-Laminin G module in Neurexin IV is essential for the apico-lateral localization of Contactin and organization of septate junctions. PLoS One 2011; 6:e25926. [PMID: 22022470 PMCID: PMC3195077 DOI: 10.1371/journal.pone.0025926] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 09/13/2011] [Indexed: 01/01/2023] Open
Abstract
Septate junctions (SJs) display a unique ultrastructural morphology with ladder-like electron densities that are conserved through evolution. Genetic and molecular analyses have identified a highly conserved core complex of SJ proteins consisting of three cell adhesion molecules Neurexin IV, Contactin, and Neuroglian, which interact with the cytoskeletal FERM domain protein Coracle. How these individual proteins interact to form the septal arrays that create the paracellular barrier is poorly understood. Here, we show that point mutations that map to specific domains of neurexin IV lead to formation of fewer septae and disorganization of SJs. Consistent with these observations, our in vivo domain deletion analyses identified the first Laminin G-EGF-Laminin G module in the extracellular region of Neurexin IV as necessary for the localization of and association with Contactin. Neurexin IV protein that is devoid of its cytoplasmic region is able to create septae, but fails to form a full complement of SJs. These data provide the first in vivo evidence that specific domains in Neurexin IV are required for protein-protein interactions and organization of SJs. Given the molecular conservation of SJ proteins across species, our studies may provide insights into how vertebrate axo-glial SJs are organized in myelinated axons.
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Cifuentes-Diaz C, Chareyre F, Garcia M, Devaux J, Carnaud M, Levasseur G, Niwa-Kawakita M, Harroch S, Girault JA, Giovannini M, Goutebroze L. Protein 4.1B contributes to the organization of peripheral myelinated axons. PLoS One 2011; 6:e25043. [PMID: 21966409 PMCID: PMC3180372 DOI: 10.1371/journal.pone.0025043] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 08/23/2011] [Indexed: 12/26/2022] Open
Abstract
Neurons are characterized by extremely long axons. This exceptional cell shape is likely to depend on multiple factors including interactions between the cytoskeleton and membrane proteins. In many cell types, members of the protein 4.1 family play an important role in tethering the cortical actin-spectrin cytoskeleton to the plasma membrane. Protein 4.1B is localized in myelinated axons, enriched in paranodal and juxtaparanodal regions, and also all along the internodes, but not at nodes of Ranvier where are localized the voltage-dependent sodium channels responsible for action potential propagation. To shed light on the role of protein 4.1B in the general organization of myelinated peripheral axons, we studied 4.1B knockout mice. These mice displayed a mildly impaired gait and motility. Whereas nodes were unaffected, the distribution of Caspr/paranodin, which anchors 4.1B to the membrane, was disorganized in paranodal regions and its levels were decreased. In juxtaparanodes, the enrichment of Caspr2, which also interacts with 4.1B, and of the associated TAG-1 and Kv1.1, was absent in mutant mice, whereas their levels were unaltered. Ultrastructural abnormalities were observed both at paranodes and juxtaparanodes. Axon calibers were slightly diminished in phrenic nerves and preterminal motor axons were dysmorphic in skeletal muscle. βII spectrin enrichment was decreased along the axolemma. Electrophysiological recordings at 3 post-natal weeks showed the occurrence of spontaneous and evoked repetitive activity indicating neuronal hyperexcitability, without change in conduction velocity. Thus, our results show that in myelinated axons 4.1B contributes to the stabilization of membrane proteins at paranodes, to the clustering of juxtaparanodal proteins, and to the regulation of the internodal axon caliber.
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Affiliation(s)
- Carmen Cifuentes-Diaz
- Inserm, UMR-S 839, Paris, France
- Université Pierre et Marie Curie (UPMC), Paris, France
- Institut du Fer à Moulin, Paris, France
| | - Fabrice Chareyre
- Inserm, U674, Institut Universitaire d'Hématologie, Paris, France
| | - Marta Garcia
- Inserm, UMR-S 839, Paris, France
- Université Pierre et Marie Curie (UPMC), Paris, France
- Institut du Fer à Moulin, Paris, France
| | - Jérôme Devaux
- Département de Signalisation Neuronale, CRN2M, UMR 6231, CNRS, Université de la Méditerranée-Université Paul Cézanne, IFR Jean Roche, Marseille, France
| | - Michèle Carnaud
- Inserm, UMR-S 839, Paris, France
- Université Pierre et Marie Curie (UPMC), Paris, France
- Institut du Fer à Moulin, Paris, France
| | - Grégoire Levasseur
- Inserm, UMR-S 839, Paris, France
- Université Pierre et Marie Curie (UPMC), Paris, France
- Institut du Fer à Moulin, Paris, France
| | | | - Sheila Harroch
- Département de Neuroscience, Institut Pasteur, Paris, France
| | - Jean-Antoine Girault
- Inserm, UMR-S 839, Paris, France
- Université Pierre et Marie Curie (UPMC), Paris, France
- Institut du Fer à Moulin, Paris, France
- * E-mail:
| | - Marco Giovannini
- Inserm, U674, Institut Universitaire d'Hématologie, Paris, France
| | - Laurence Goutebroze
- Inserm, UMR-S 839, Paris, France
- Université Pierre et Marie Curie (UPMC), Paris, France
- Institut du Fer à Moulin, Paris, France
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Rodrigues F, Schmidt I, Klämbt C. Comparing peripheral glial cell differentiation in Drosophila and vertebrates. Cell Mol Life Sci 2011; 68:55-69. [PMID: 20820850 PMCID: PMC11114915 DOI: 10.1007/s00018-010-0512-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 08/13/2010] [Accepted: 08/16/2010] [Indexed: 01/08/2023]
Abstract
In all complex organisms, the peripheral nerves ensure the portage of information from the periphery to central computing and back again. Axons are in part amazingly long and are accompanied by several different glial cell types. These peripheral glial cells ensure electrical conductance, most likely nature the long axon, and establish and maintain a barrier towards extracellular body fluids. Recent work has revealed a surprisingly similar organization of peripheral nerves of vertebrates and Drosophila. Thus, the genetic dissection of glial differentiation in Drosophila may also advance our understanding of basic principles underlying the development of peripheral nerves in vertebrates.
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Affiliation(s)
| | - Imke Schmidt
- Institut für Neurobiologie, Badestr. 9, 48149 Münster, Germany
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In vivo deletion of immunoglobulin domains 5 and 6 in neurofascin (Nfasc) reveals domain-specific requirements in myelinated axons. J Neurosci 2010; 30:4868-76. [PMID: 20371806 DOI: 10.1523/jneurosci.5951-09.2010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The formation of paranodal axo-glial junctions is critical for the rapid and efficient propagation of nerve impulses. Genetic ablation of genes encoding the critical paranodal proteins Caspr, contactin (Cont), and the myelinating glia-specific isoform of Neurofascin (Nfasc(NF155)) results in the disruption of the paranodal axo-glial junctions, loss of ion channel segregation, and impaired nerve conduction, but the mechanisms regulating their interactions remain elusive. Here, we report that loss of immunoglobulin (Ig) domains 5 and 6 in Nfasc(NF155) in mice phenocopies complete ablation of Nfasc(NF155). The mutant mice lack paranodal septate junctions, resulting in the diffusion of Caspr and Cont from the paranodes, and redistribution of the juxtaparanodal potassium channels toward the nodes. Although critical for Nfasc(NF155) function, we find that Ig5-6 are dispensable for nodal Nfasc(NF186) function. Moreover, in vitro binding assays using Ig5-6 deletion constructs reveal their importance for the association of Nfasc(NF155) with Cont. These findings provide the first molecular evidence demonstrating domain-specific requirements controlling the association of the paranodal tripartite complex in vivo. Our studies further emphasize that in vivo structure/function analysis is necessary to define the unique protein-protein interactions that differentially regulate the functions of Neurofascins during axonal domain organization.
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Organization of myelinated axons by Caspr and Caspr2 requires the cytoskeletal adapter protein 4.1B. J Neurosci 2010; 30:2480-9. [PMID: 20164332 DOI: 10.1523/jneurosci.5225-09.2010] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Caspr and Caspr2 regulate the formation of distinct axonal domains around the nodes of Ranvier. Caspr is required for the generation of a membrane barrier at the paranodal junction (PNJ), whereas Caspr2 serves as a membrane scaffold that clusters Kv1 channels at the juxtaparanodal region (JXP). Both Caspr and Caspr2 interact with protein 4.1B, which may link the paranodal and juxtaparanodal adhesion complexes to the axonal cytoskeleton. To determine the role of protein 4.1B in the function of Caspr proteins, we examined the ability of transgenic Caspr and Caspr2 mutants lacking their 4.1-binding sequence (d4.1) to restore Kv1 channel clustering in Caspr- and Caspr2-null mice, respectively. We found that Caspr-d4.1 was localized to the PNJ and is able to recruit the paranodal adhesion complex components contactin and NF155 to this site. Nevertheless, in axons expressing Caspr-d4.1, Kv1 channels were often detected at paranodes, suggesting that the interaction of Caspr with protein 4.1B is necessary for the generation of an efficient membrane barrier at the PNJ. We also found that the Caspr2-d4.1 transgene did not accumulate at the JXP, even though it was targeted to the axon, demonstrating that the interaction with protein 4.1B is required for the accumulation of Caspr2 and Kv1 channels at the juxtaparanodal axonal membrane. In accordance, we show that Caspr2 and Kv1 channels are not clustered at the JXP in 4.1B-null mice. Our results thus underscore the functional importance of protein 4.1B in the organization of peripheral myelinated axons.
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31
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Eisenbach M, Kartvelishvily E, Eshed-Eisenbach Y, Watkins T, Sorensen A, Thomson C, Ranscht B, Barnett SC, Brophy P, Peles E. Differential clustering of Caspr by oligodendrocytes and Schwann cells. J Neurosci Res 2010; 87:3492-501. [PMID: 19565653 DOI: 10.1002/jnr.22157] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Formation of the paranodal axoglial junction (PNJ) requires the presence of three cell adhesion molecules: the 155-kDa isoform of neurofascin (NF155) on the glial membrane and a complex of Caspr and contactin found on the axolemma. Here we report that the clustering of Caspr along myelinated axons during development differs fundamentally between the central (CNS) and peripheral (PNS) nervous systems. In cultures of Schwann cells (SC) and dorsal root ganglion (DRG) neurons, membrane accumulation of Caspr was detected only after myelination. In contrast, in oligodendrocytes (OL)/DRG neurons cocultures, Caspr was clustered upon initial glial cell contact already before myelination had begun. Premyelination clustering of Caspr was detected in cultures of oligodendrocytes and retinal ganglion cells, motor neurons, and DRG neurons as well as in mixed cell cultures of rat forebrain and spinal cords. Cocultures of oligodendrocyte precursor cells isolated from contactin- or neurofascin-deficient mice with wild-type DRG neurons showed that clustering of Caspr at initial contact sites between OL processes and the axon requires glial expression of NF155 but not of contactin. These results demonstrate that the expression of membrane proteins along the axolemma is determined by the type of the contacting glial cells and is not an intrinsic characteristic of the axon.
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Affiliation(s)
- Menahem Eisenbach
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel
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32
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Pomicter AD, Shroff SM, Fuss B, Sato-Bigbee C, Brophy PJ, Rasband MN, Bhat MA, Dupree JL. Novel forms of neurofascin 155 in the central nervous system: alterations in paranodal disruption models and multiple sclerosis. Brain 2010; 133:389-405. [PMID: 20129933 PMCID: PMC2822635 DOI: 10.1093/brain/awp341] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 12/14/2009] [Accepted: 12/16/2009] [Indexed: 01/08/2023] Open
Abstract
Stability of the myelin-axon unit is achieved, at least in part, by specialized paranodal junctions comprised of the neuronal heterocomplex of contactin and contactin-associated protein and the myelin protein neurofascin 155. In multiple sclerosis, normal distribution of these proteins is altered, resulting in the loss of the insulating myelin and consequently causing axonal dysfunction. Previously, this laboratory reported that mice lacking the myelin-enriched lipid sulphatide are characterized by a progressive deterioration of the paranodal structure. Here, it is shown that this deterioration is preceded by significant loss of neurofascin 155 clustering at the myelin paranode. Interestingly, prolonged electrophoretic separation revealed the existence of two neurofascin 155 bands, neurofascin 155 high and neurofascin 155 low, which are readily observed following N-linked deglycosylation. Neurofascin 155 high is observed at 7 days of age and reaches peak expression at one month of age, while neurofascin 155 low is first observed at 14 days of age and constantly increases until 5 months of age. Studies using conditional neurofascin knockout mice indicated that neurofascin 155 high and neurofascin 155 low are products of the neurofascin gene and are exclusively expressed by oligodendrocytes within the central nervous system. Neurofascin 155 high is a myelin paranodal protein while the distribution of neurofascin 155 low remains to be determined. While neurofascin 155 high levels are significantly reduced in the sulphatide null mice at 15 days, 30 days and 4 months of age, neurofascin 155 low levels remain unaltered. Although maintained at normal levels, neurofascin 155 low is incapable of preserving paranodal structure, thus indicating that neurofascin 155 high is required for paranodal stability. Additionally, comparisons between neurofascin 155 high and neurofascin 155 low in human samples revealed a significant alteration, specifically in multiple sclerosis plaques.
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Affiliation(s)
- Anthony D. Pomicter
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | - Seema M. Shroff
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | - Babette Fuss
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | - Carmen Sato-Bigbee
- 2 Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, School of Medicine, Richmond, Virginia, USA
| | - Peter J. Brophy
- 3 Centre for Neuroscience Research, University of Edinburgh, Edinburgh, Scotland, UK
| | - Matthew N. Rasband
- 4 Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
| | - Manzoor A. Bhat
- 5 Department of Cell and Molecular Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Jeffrey L. Dupree
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
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A Novel Caspr Mutation Causes the Shambling Mouse Phenotype by Disrupting Axoglial Interactions of Myelinated Nerves. J Neuropathol Exp Neurol 2009; 68:1207-18. [DOI: 10.1097/nen.0b013e3181be2e96] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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34
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Labasque M, Faivre-Sarrailh C. GPI-anchored proteins at the node of Ranvier. FEBS Lett 2009; 584:1787-92. [PMID: 19703450 DOI: 10.1016/j.febslet.2009.08.025] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 08/19/2009] [Indexed: 01/06/2023]
Abstract
Contactin and TAG-1 are glycan phosphatidyl inositol (GPI)-anchored cell adhesion molecules that play a crucial role in the organization of axonal subdomains at the node of Ranvier of myelinating fibers. Contactin and TAG-1 mediate axo-glial selective interactions in association with Caspr-family molecules at paranodes and juxtaparanodes, respectively. How membrane proteins can be confined in these neighbouring domains along the axon has been the subject of intense investigations. This review will specifically examine the properties conferred by the lipid microenvironment to regulate trafficking and selective association of these axo-glial complexes. Increasing evidences from genetic and neuropathological models point to a role of lipid rafts in the formation or stabilization of the paranodal junctions.
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Affiliation(s)
- Marilyne Labasque
- Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, UMR 6231 CNRS, Université de la Méditerranée, Marseille, France
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35
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Pillai AM, Thaxton C, Pribisko AL, Cheng JG, Dupree JL, Bhat MA. Spatiotemporal ablation of myelinating glia-specific neurofascin (Nfasc NF155) in mice reveals gradual loss of paranodal axoglial junctions and concomitant disorganization of axonal domains. J Neurosci Res 2009; 87:1773-93. [PMID: 19185024 DOI: 10.1002/jnr.22015] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The evolutionary demand for rapid nerve impulse conduction led to the process of myelination-dependent organization of axons into distinct molecular domains. These domains include the node of Ranvier flanked by highly specialized paranodal domains where myelin loops and axolemma orchestrate the axoglial septate junctions. These junctions are formed by interactions between a glial isoform of neurofascin (Nfasc(NF155)) and axonal Caspr and Cont. Here we report the generation of myelinating glia-specific Nfasc(NF155) null mouse mutants. These mice exhibit severe ataxia, motor paresis, and death before the third postnatal week. In the absence of glial Nfasc(NF155), paranodal axoglial junctions fail to form, axonal domains fail to segregate, and myelinated axons undergo degeneration. Electrophysiological measurements of peripheral nerves from Nfasc(NF155) mutants revealed dramatic reductions in nerve conduction velocities. By using inducible PLP-CreER recombinase to ablate Nfasc(NF155) in adult myelinating glia, we demonstrate that paranodal axoglial junctions disorganize gradually as the levels of Nfasc(NF155) protein at the paranodes begin to drop. This coincides with the loss of the paranodal region and concomitant disorganization of the axonal domains. Our results provide the first direct evidence that the maintenance of axonal domains requires the fence function of the paranodal axoglial junctions. Together, our studies establish a central role for paranodal axoglial junctions in both the organization and the maintenance of axonal domains in myelinated axons.
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Affiliation(s)
- Anilkumar M Pillai
- Department of Cell and Molecular Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7545, USA
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Lewis(x) and alpha2,3-sialyl glycans and their receptors TAG-1, Contactin, and L1 mediate CD24-dependent neurite outgrowth. J Neurosci 2009; 29:6677-90. [PMID: 19458237 DOI: 10.1523/jneurosci.4361-08.2009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Although carbohydrates have been implicated in cell interactions in the nervous system, the molecular bases of their functions have remained largely obscure. Here, we show that promotion or inhibition of neurite outgrowth of cerebellar or dorsal root ganglion neurons, respectively, induced by the mucin-type adhesion molecule CD24 depends on alpha2,3-linked sialic acid and Lewis(x) present on glia-specific CD24 glycoforms. Alpha2,3-sialyl residues of CD24 bind to a structural motif in the first fibronectin type III domain of the adhesion molecule L1. Following the observation that the adhesion molecules TAG-1 and Contactin show sequence homologies with fucose-specific lectins, we obtained evidence that TAG-1 and Contactin mediate Lewis(x)-dependent CD24-induced effects on neurite outgrowth. Thus, L1, TAG-1, and Contactin function as lectin-like neuronal receptors. Their cis interactions with neighboring adhesion molecules, e.g., Caspr1 and Caspr2, and with their triggered signal transduction pathways elicit cell type-specific promotion or inhibition of neurite outgrowth induced by glial CD24 in a glycan-dependent trans interaction.
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Salzer JL, Brophy PJ, Peles E. Molecular domains of myelinated axons in the peripheral nervous system. Glia 2009; 56:1532-1540. [PMID: 18803321 DOI: 10.1002/glia.20750] [Citation(s) in RCA: 159] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Myelinated axons are organized into a series of specialized domains with distinct molecular compositions and functions. These domains, which include the node of Ranvier, the flanking paranodal junctions, the juxtaparanodes, and the internode, form as the result of interactions with myelinating Schwann cells. This domain organization is essential for action potential propagation by saltatory conduction and for the overall function and integrity of the axon.
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Affiliation(s)
- James L Salzer
- Department of Cell Biology and Neurology, and the Smilow Neuroscience Program, NYU School of Medicine, New York, New York 10016, USA.
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38
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Oiso S, Takeda Y, Futagawa T, Miura T, Kuchiiwa S, Nishida K, Ikeda R, Kariyazono H, Watanabe K, Yamada K. Contactin-associated protein (Caspr) 2 interacts with carboxypeptidase E in the CNS. J Neurochem 2009; 109:158-67. [PMID: 19166515 DOI: 10.1111/j.1471-4159.2009.05928.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To identify proteins interacting with the intracellular domain of the neural cell adhesion molecule contactin-associated protein 2 (Caspr2), yeast two-hybrid screening was performed. We identified carboxypeptidase E (CPE) as a Caspr2-interacting candidate protein. Glutathione S-transferase pull-down and immunoprecipitation analyses indicated that Caspr2 was associated with CPE in vitro and in vivo. Both Caspr2 and CPE were expressed predominantly in the CNS. Immunohistochemical analyses revealed that both Caspr2- and CPE-like immunoreactivities were found to co-localize in the apical dendrites and cell bodies of rat cortical neurons. In subcellular localization analysis, Caspr2- and CPE-like immunoreactivities were co-migrated in the fractions of Golgi/ER. Additionally, in COS-7 cells co-transfected with CPE and Caspr2 cDNAs, Caspr2- and CPE-immunoreactivities were co-localized in both Golgi and membrane, whereas it was only observed in Golgi of either COS-7 cell transfected with CPE or Caspr2 cDNA alone. It is known that the membrane-bound form of CPE functions as a sorting receptor of prohormones in the trans-Golgi network. Taken together, our data suggest that CPE may be a key molecule to regulate Caspr2 trafficking to the cell membrane.
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Affiliation(s)
- Shigeru Oiso
- Department of Clinical Pharmacy and Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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39
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Shimoda Y, Watanabe K. Contactins: emerging key roles in the development and function of the nervous system. Cell Adh Migr 2009; 3:64-70. [PMID: 19262165 DOI: 10.4161/cam.3.1.7764] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Contactins are a subgroup of molecules belonging to the immunoglobulin superfamily that are expressed exclusively in the nervous system. The subgroup consists of six members: contactin, TAG-1, BIG-1, BIG-2, NB-2 and NB-3. Since their identification in the late 1980s, contactin and TAG-1 have been studied extensively. Axonal expression and the neurite extension activity of contactin and TAG-1 attracted researchers to study the function of these molecules in axon guidance during development. After the exciting discovery of the molecular function of contactin and TAG-1 in myelination earlier this decade, these two molecules have come to be known as the principal molecules in the function and maintenance of myelinated neurons. In contrast, the function of the other four members of this subgroup remained unknown until recently. Here, we will give an overview of contactin function, including recent progress on BIG-2, NB-2 and NB-3.
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Affiliation(s)
- Yasushi Shimoda
- Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
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40
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Bizzoca A, Corsi P, Gennarini G. The mouse F3/contactin glycoprotein: structural features, functional properties and developmental significance of its regulated expression. Cell Adh Migr 2009; 3:53-63. [PMID: 19372728 PMCID: PMC2675150 DOI: 10.4161/cam.3.1.7462] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2008] [Accepted: 11/19/2008] [Indexed: 12/18/2022] Open
Abstract
F3/Contactin is an immunoglobulin superfamily component expressed in the nervous tissue of several species. Here we focus on the structural and functional properties of its mouse relative, on the mechanisms driving its regulated expression and on its developmental role. F3/Contactin is differentially expressed in distinct populations of central and peripheral neurons and in some non-neuronal cells. Accordingly, the regulatory region of the underlying gene includes promoter elements undergoing differential activation, associated with an intricate splicing profile, indicating that transcriptional and posttranscriptional mechanisms contribute to its expression. Transgenic models allowed to follow F3/Contactin promoter activation in vivo and to modify F3/Contactin gene expression under a heterologous promoter, which resulted in morphological and functional phenotypes. Besides axonal growth and pathfinding, these concerned earlier events, including precursor proliferation and commitment. This wide role in neural ontogenesis is consistent with the recognized interaction of F3/Contactin with developmental control genes belonging to the Notch pathway.
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Affiliation(s)
- Antonella Bizzoca
- Department of Pharmacology and Human Physiology, Medical School, University of Bari, Bari, Italy
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41
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Abstract
Paranodal axoglial junctions are essential for the segregation of myelinated axons into distinct domains and efficient conduction of action potentials. Here, we show that netrin-1 and deleted in colorectal cancer (DCC) are enriched at the paranode in CNS myelin. We then address whether netrin-1 signaling influences paranodal adhesion between oligodendrocytes and axons. In the absence of netrin-1 or DCC function, oligodendroglial paranodes initially develop and mature normally but later become disorganized. Lack of DCC or netrin-1 resulted in detachment of paranodal loops from the axonal surface and the disappearance of transverse bands. Furthermore, the domain organization of myelin is compromised in the absence of netrin-1 signaling: K+ channels inappropriately invade the paranodal region, and the normally restricted paranodal distribution of Caspr expands longitudinally along the axon. Our findings identify an essential role for netrin-1 and DCC regulating the maintenance of axoglial junctions.
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42
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Martin PM, Cifuentes-Diaz C, Garcia M, Goutebroze L, Girault JA. [Axon and Schwann cells... so far away, so close]. Rev Neurol (Paris) 2008; 164:1057-62. [PMID: 19041107 DOI: 10.1016/j.neurol.2008.10.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Myelination was a major step in the evolution of the nervous system. Appearing first in jaw fish, myelination allows the fast and secure propagation of action potentials at a low energetic cost, and without exaggerated increase in axonal diameter. In the peripheral nervous system of mammals, myelination results from the tight interactions between Schwann cells and axons, leading to the formation of highly differentiated domains along the axon. The molecular determinants of these interactions are starting to be well identified. Their understanding provides a precise framework to interpret the defects, which occur in pathological circumstances. This review summarizes the present state of knowledge concerning axoglial interactions in peripheral nerves.
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Affiliation(s)
- P-M Martin
- Inserm UMR-S 839, institut du Fer-à-Moulin, 17, rue du Fer-à-Moulin, 75005 Paris, France
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43
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Pillai AM, Garcia-Fresco GP, Sousa AD, Dupree JL, Philpot BD, Bhat MA. No effect of genetic deletion of contactin-associated protein (CASPR) on axonal orientation and synaptic plasticity. J Neurosci Res 2007; 85:2318-31. [PMID: 17549747 PMCID: PMC2824167 DOI: 10.1002/jnr.21374] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Myelinated axons are endowed with a specialized domain structure that is essential for saltatory action potential conduction. The paranodal domain contains the axoglial junctions and displays a unique ultrastructure that resembles the invertebrate septate junctions (SJs). Biochemical characterizations of the paranodal axoglial SJs have identified several molecular components that include Caspr and contactin (Cont) on the axonal side and neurofascin 155 kDa (NF155) isoform on the glial side. All these proteins are essential for the formation of the axoglial SJs. Based on the interactions between Caspr and Cont and their colocalization in the CA1 synaptic areas, it was proposed that the synaptic function of Cont requires Caspr. Here we have extended the phenotypic analysis of CASPR mutants to address further the role of Caspr at the axoglial SJs and also in axonal orientation and synaptic plasticity. We report that, in CASPR mutants, the smooth endoplasmic reticulum (SER) forms elongated membranous complexes that accumulate at the nodal/paranodal region and stretch into the juxtaparanodal region, a defect that is consistent with the paranodal disorganization. We show that the cerebellar microorganization is unaffected in CASPR mutants. We also demonstrate that Caspr function is not essential for normal CA1 synaptic transmission and plasticity. Taken together with previous findings, our results highlight that the Caspr/Cont complex is essential for the formation of axoglial SJs, whereas Cont may regulate axonal orientation and synaptic plasticity independent of its association with Caspr.
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Affiliation(s)
- Anilkumar M. Pillai
- Department of Cell and Molecular Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - German P. Garcia-Fresco
- Curriculum in Neurobiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Aurea D. Sousa
- Department of Cell and Molecular Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Jeffrey L. Dupree
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia
| | - Benjamin D. Philpot
- Department of Cell and Molecular Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
- Curriculum in Neurobiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
- UNC-Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Manzoor A. Bhat
- Department of Cell and Molecular Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
- Curriculum in Neurobiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
- UNC-Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
- Neurodevelopmental Disorders Research Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
- Correspondence to: Manzoor Bhat, Department of Cell and Molecular Physiology, Neuroscience Research Building 5109F, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7545.
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Perkins GA, Sosinsky GE, Ghassemzadeh S, Perez A, Jones Y, Ellisman MH. Electron tomographic analysis of cytoskeletal cross-bridges in the paranodal region of the node of Ranvier in peripheral nerves. J Struct Biol 2007; 161:469-80. [PMID: 18096402 DOI: 10.1016/j.jsb.2007.10.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 10/05/2007] [Accepted: 10/08/2007] [Indexed: 11/25/2022]
Abstract
The node of Ranvier is a site for ionic conductances along myelinated nerves and governs the saltatory transmission of action potentials. Defects in the cross-bridging and spacing of the cytoskeleton are a prominent pathological feature in diseases of the peripheral nerve. Electron tomography was used to examine cytoskeletal-cytoskeletal, membrane-cytoskeletal, and heterologous cell connections in the paranodal region of the node of Ranvier in peripheral nerves. Focal attachment of cytoskeletal filaments to each other and to the axolemma and paranodal membranes of the Schwann cell via narrow cross-bridges was visualized in both neuronal and glial cytoplasm. A subset of intermediate filaments associates with the cytoplasmic surfaces of supramolecular complexes of transmembrane structures that are presumed to include known and unknown junctional proteins. Mitochondria were linked to both microtubules and neurofilaments in the axoplasm and to neighboring smooth endoplasmic reticulum by narrow cross-bridges. Tubular cisternae in the glial cytoplasm were also linked to the paranodal glial cytoplasmic loop juxtanodal membrane by short cross-bridges. In the extracellular matrix between axon and Schwann cell, junctional bridges formed long cylinders linking the two membranes. Interactions between cytoskeleton, membranes, and extracellular matrix associations in the paranodal region are likely critical not only for scaffolding, but also for intracellular and extracellular communication.
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Affiliation(s)
- Guy A Perkins
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, 9500 Gilman Drive, La jolla, CA 92093-0608, USA.
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