1
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Bekku Y, Zotter B, You C, Piehler J, Leonard WJ, Salzer JL. Glia trigger endocytic clearance of axonal proteins to promote rodent myelination. Dev Cell 2024; 59:627-644.e10. [PMID: 38309265 PMCID: PMC11089820 DOI: 10.1016/j.devcel.2024.01.008] [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: 03/05/2023] [Revised: 09/09/2023] [Accepted: 01/12/2024] [Indexed: 02/05/2024]
Abstract
Axons undergo striking changes in their content and distribution of cell adhesion molecules (CAMs) and ion channels during myelination that underlies the switch from continuous to saltatory conduction. These changes include the removal of a large cohort of uniformly distributed CAMs that mediate initial axon-Schwann cell interactions and their replacement by a subset of CAMs that mediate domain-specific interactions of myelinated fibers. Here, using rodent models, we examine the mechanisms and significance of this removal of axonal CAMs. We show that Schwann cells just prior to myelination locally activate clathrin-mediated endocytosis (CME) in axons, thereby driving clearance of a broad array of axonal CAMs. CAMs engineered to resist endocytosis are persistently expressed along the axon and delay both PNS and CNS myelination. Thus, glia non-autonomously activate CME in axons to downregulate axonal CAMs and presumptively axo-glial adhesion. This promotes the transition from ensheathment to myelination while simultaneously sculpting the formation of axonal domains.
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Affiliation(s)
- Yoko Bekku
- Neuroscience Institute, New York University Langone Medical Center, New York, NY 10016, USA.
| | - Brendan Zotter
- Neuroscience Institute, New York University Langone Medical Center, New York, NY 10016, USA
| | - Changjiang You
- Department of Biology/Chemistry and Center for Cellular Nanoanalytics, Osnabrück University, Barbarastr. 11, 49076 Osnabrück, Germany
| | - Jacob Piehler
- Department of Biology/Chemistry and Center for Cellular Nanoanalytics, Osnabrück University, Barbarastr. 11, 49076 Osnabrück, Germany
| | - Warren J Leonard
- Laboratory of Molecular Immunology and Immunology Center, National Heart, Lung, and Blood Institute, National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - James L Salzer
- Neuroscience Institute, New York University Langone Medical Center, New York, NY 10016, USA.
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2
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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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3
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Appeltshauser L, Linke J, Heil HS, Karus C, Schenk J, Hemmen K, Sommer C, Doppler K, Heinze KG. Super-resolution imaging pinpoints the periodic ultrastructure at the human node of Ranvier and its disruption in patients with polyneuropathy. Neurobiol Dis 2023; 182:106139. [PMID: 37146836 DOI: 10.1016/j.nbd.2023.106139] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/13/2023] [Accepted: 04/25/2023] [Indexed: 05/07/2023] Open
Abstract
The node of Ranvier is the key element in saltatory conduction along myelinated axons, but its specific protein organization remains elusive in the human species. To shed light on nanoscale anatomy of the human node of Ranvier in health and disease, we assessed human nerve biopsies of patients with polyneuropathy by super-resolution fluorescence microscopy. We applied direct stochastic optical reconstruction microscopy (dSTORM) and supported our data by high-content confocal imaging combined with deep learning-based analysis. As a result, we revealed a ~ 190 nm periodic protein arrangement of cytoskeletal proteins and axoglial cell adhesion molecules in human peripheral nerves. In patients with polyneuropathy, periodic distances increased at the paranodal region of the node of Ranvier, both at the axonal cytoskeleton and at the axoglial junction. In-depth image analysis revealed a partial loss of proteins of the axoglial complex (Caspr-1, neurofascin-155) in combination with detachment from the cytoskeletal anchor protein ß2-spectrin. High content analysis showed that such paranodal disorganization occurred especially in acute and severe axonal neuropathy with ongoing Wallerian degeneration and related cytoskeletal damage. We provide nanoscale and protein-specific evidence for the prominent, but vulnerable role of the node of Ranvier for axonal integrity. Furthermore, we show that super-resolution imaging can identify, quantify and map elongated periodic protein distances and protein interaction in histopathological tissue samples. We thus introduce a promising tool for further translational applications of super resolution microscopy.
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Affiliation(s)
| | - Janis Linke
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany; Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Hannah S Heil
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany; Optical Cell Biology, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Christine Karus
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Joachim Schenk
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Katherina Hemmen
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Claudia Sommer
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Kathrin Doppler
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany.
| | - Katrin G Heinze
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany.
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4
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Kozar-Gillan N, Velichkova A, Kanatouris G, Eshed-Eisenbach Y, Steel G, Jaegle M, Aunin E, Peles E, Torsney C, Meijer DN. LGI3/2-ADAM23 interactions cluster Kv1 channels in myelinated axons to regulate refractory period. J Cell Biol 2023; 222:e202211031. [PMID: 36828548 PMCID: PMC9997507 DOI: 10.1083/jcb.202211031] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/18/2022] [Accepted: 01/17/2023] [Indexed: 02/26/2023] Open
Abstract
Along myelinated axons, Shaker-type potassium channels (Kv1) accumulate at high density in the juxtaparanodal region, directly adjacent to the paranodal axon-glia junctions that flank the nodes of Ranvier. However, the mechanisms that control the clustering of Kv1 channels, as well as their function at this site, are still poorly understood. Here we demonstrate that axonal ADAM23 is essential for both the accumulation and stability of juxtaparanodal Kv1 complexes. The function of ADAM23 is critically dependent on its interaction with its extracellular ligands LGI2 and LGI3. Furthermore, we demonstrate that juxtaparanodal Kv1 complexes affect the refractory period, thus enabling high-frequency burst firing of action potentials. Our findings not only reveal a previously unknown molecular pathway that regulates Kv1 channel clustering, but they also demonstrate that the juxtaparanodal Kv1 channels that are concealed below the myelin sheath, play a significant role in modifying axonal physiology.
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Affiliation(s)
- Nina Kozar-Gillan
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
| | | | - George Kanatouris
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
| | - Yael Eshed-Eisenbach
- Department of Molecular Cell Biology and Molecular Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Gavin Steel
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
| | | | - Eerik Aunin
- Biomedical Sciences, ErasmusMC, Rotterdam, Netherlands
| | - Elior Peles
- Department of Molecular Cell Biology and Molecular Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Carole Torsney
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh. UK
| | - Dies N. Meijer
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK
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5
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iTRAQ-based proteomics analysis on insomnia rats treated with Mongolian medical warm acupuncture. Biosci Rep 2021; 40:222577. [PMID: 32249904 PMCID: PMC7953503 DOI: 10.1042/bsr20191517] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 02/17/2020] [Accepted: 03/09/2020] [Indexed: 01/20/2023] Open
Abstract
Objective: To explore the proteomic changes in the hypothalamus of rats treated with Mongolian medical warm acupuncture for insomnia therapy based proteomics. Method: We used an iTRAQ-based quantitative proteomic approach to identify proteins that potential molecular mechanisms involved in the treatment of insomnia by Mongolian medical warm acupuncture. Result: In total, 7477 proteins were identified, of which 36 proteins showed increased levels and 45 proteins showed decreased levels in insomnia model group (M) compared with healthy control group (C), 72 proteins showed increased levels and 44 proteins showed decreased levels from the warm acupuncture treated insomnia group (W) compared with healthy controls (C), 28 proteins showed increased levels and 17 proteins showed decreased levels from the warm acupuncture-treated insomnia group (W) compared with insomnia model group (M). Compared with healthy control groups, warm acupuncture-treated insomnia group showed obvious recovered. Bioinformatics analysis indicated that up-regulation of neuroactive ligand–receptor interaction and oxytocin signaling was the most significantly elevated regulate process of Mongolian medical warm acupuncture treatment for insomnia. Proteins showed that increased/decreased expression in the warm acupuncture-treated insomnia group included Prolargin (PRELP), NMDA receptor synaptonuclear-signaling and neuronal migration factor (NSMF), Transmembrane protein 41B (TMEM41B) and Microtubule-associated protein 1B (MAP1B) to adjust insomnia. Conclusion: A combination of findings in the present study suggest that warm acupuncture treatment is efficacious in improving sleep by regulating the protein expression process in an experimental rat model and may be of potential benefit in treating insomnia patients with the added advantage with no adverse effects.
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Kalafatakis I, Savvaki M, Velona T, Karagogeos D. Implication of Contactins in Demyelinating Pathologies. Life (Basel) 2021; 11:life11010051. [PMID: 33451101 PMCID: PMC7828632 DOI: 10.3390/life11010051] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/09/2021] [Accepted: 01/11/2021] [Indexed: 12/19/2022] Open
Abstract
Demyelinating pathologies comprise of a variety of conditions where either central or peripheral myelin is attacked, resulting in white matter lesions and neurodegeneration. Myelinated axons are organized into molecularly distinct domains, and this segregation is crucial for their proper function. These defined domains are differentially affected at the different stages of demyelination as well as at the lesion and perilesion sites. Among the main players in myelinated axon organization are proteins of the contactin (CNTN) group of the immunoglobulin superfamily (IgSF) of cell adhesion molecules, namely Contactin-1 and Contactin-2 (CNTN1, CNTN2). The two contactins perform their functions through intermolecular interactions, which are crucial for myelinated axon integrity and functionality. In this review, we focus on the implication of these two molecules as well as their interactors in demyelinating pathologies in humans. At first, we describe the organization and function of myelinated axons in the central (CNS) and the peripheral (PNS) nervous system, further analyzing the role of CNTN1 and CNTN2 as well as their interactors in myelination. In the last section, studies showing the correlation of the two contactins with demyelinating pathologies are reviewed, highlighting the importance of these recognition molecules in shaping the function of the nervous system in multiple ways.
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7
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Assembly and Function of the Juxtaparanodal Kv1 Complex in Health and Disease. Life (Basel) 2020; 11:life11010008. [PMID: 33374190 PMCID: PMC7824554 DOI: 10.3390/life11010008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 12/21/2020] [Accepted: 12/23/2020] [Indexed: 02/07/2023] Open
Abstract
The precise axonal distribution of specific potassium channels is known to secure the shape and frequency of action potentials in myelinated fibers. The low-threshold voltage-gated Kv1 channels located at the axon initial segment have a significant influence on spike initiation and waveform. Their role remains partially understood at the juxtaparanodes where they are trapped under the compact myelin bordering the nodes of Ranvier in physiological conditions. However, the exposure of Kv1 channels in de- or dys-myelinating neuropathy results in alteration of saltatory conduction. Moreover, cell adhesion molecules associated with the Kv1 complex, including Caspr2, Contactin2, and LGI1, are target antigens in autoimmune diseases associated with hyperexcitability such as encephalitis, neuromyotonia, or neuropathic pain. The clustering of Kv1.1/Kv1.2 channels at the axon initial segment and juxtaparanodes is based on interactions with cell adhesion molecules and cytoskeletal linkers. This review will focus on the trafficking and assembly of the axonal Kv1 complex in the peripheral and central nervous system (PNS and CNS), during development, and in health and disease.
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8
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Gallego-Delgado P, James R, Browne E, Meng J, Umashankar S, Tan L, Picon C, Mazarakis ND, Faisal AA, Howell OW, Reynolds R. Neuroinflammation in the normal-appearing white matter (NAWM) of the multiple sclerosis brain causes abnormalities at the nodes of Ranvier. PLoS Biol 2020; 18:e3001008. [PMID: 33315860 PMCID: PMC7769608 DOI: 10.1371/journal.pbio.3001008] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 12/28/2020] [Accepted: 11/20/2020] [Indexed: 01/02/2023] Open
Abstract
Changes to the structure of nodes of Ranvier in the normal-appearing white matter (NAWM) of multiple sclerosis (MS) brains are associated with chronic inflammation. We show that the paranodal domains in MS NAWM are longer on average than control, with Kv1.2 channels dislocated into the paranode. These pathological features are reproduced in a model of chronic meningeal inflammation generated by the injection of lentiviral vectors for the lymphotoxin-α (LTα) and interferon-γ (IFNγ) genes. We show that tumour necrosis factor (TNF), IFNγ, and glutamate can provoke paranodal elongation in cerebellar slice cultures, which could be reversed by an N-methyl-D-aspartate (NMDA) receptor blocker. When these changes were inserted into a computational model to simulate axonal conduction, a rapid decrease in velocity was observed, reaching conduction failure in small diameter axons. We suggest that glial cells activated by pro-inflammatory cytokines can produce high levels of glutamate, which triggers paranodal pathology, contributing to axonal damage and conduction deficits. Current thinking on the mechanisms by which multiple sclerosis gives rise to cumulative neurological disability revolves largely around focal lesions of inflammation and demyelination. However, some of the debilitating symptoms, such as severe fatigue, might be better explained by a more diffuse pathology. This study shows that paranodes in the white matter become abnormal as a result of neuroinflammation, which may be the result of the action of cytokines that cause glia to release glutamate.
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Affiliation(s)
- Patricia Gallego-Delgado
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Rachel James
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Eleanor Browne
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Joanna Meng
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Swetha Umashankar
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Li Tan
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Carmen Picon
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Nicholas D. Mazarakis
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - A. Aldo Faisal
- Department of Bioengineering, Faculty of Engineering, Imperial College London, London, United Kingdom
- Department of Computing, Faculty of Engineering, Imperial College London, London, United Kingdom
- Data Science Institute, Imperial College London, London, United Kingdom
| | - Owain W. Howell
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
- Institute of Life Sciences, Swansea University Medical School, Swansea University, Swansea, Wales
| | - Richard Reynolds
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
- Centre for Molecular Neuropathology, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- * E-mail:
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9
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Abstract
The nodes of Ranvier have clustered Na+ and K+ channels necessary for rapid and efficient axonal action potential conduction. However, detailed mechanisms of channel clustering have only recently been identified: they include two independent axon-glia interactions that converge on distinct axonal cytoskeletons. Here, we discuss how glial cell adhesion molecules and the extracellular matrix molecules that bind them assemble combinations of ankyrins, spectrins and other cytoskeletal scaffolding proteins, which cluster ion channels. We present a detailed molecular model, incorporating these overlapping mechanisms, to explain how the nodes of Ranvier are assembled in both the peripheral and central nervous systems.
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10
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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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11
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Yuan X, Piao L, Wang L, Han X, Zhuang M, Liu Z. Pivotal roles of protein 4.1B/DAL‑1, a FERM‑domain containing protein, in tumor progression (Review). Int J Oncol 2019; 55:979-987. [PMID: 31545421 DOI: 10.3892/ijo.2019.4877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 09/04/2019] [Indexed: 11/06/2022] Open
Abstract
Protein 4.1B/DAL‑1, encoded by erythrocyte membrane protein band 4.1‑like 3 (EPB41L3), belongs to the protein 4.1 superfamily, a group of proteins that share a conserved four.one‑ezrin‑radixin‑moesin (FERM) domain. Protein 4.1B/DAL‑1 serves a crucial role in cytoskeletal organization and a number of processes through multiple interactions with membrane proteins via its FERM, spectrin‑actin‑binding and C‑terminal domains. A number of studies have indicated that a loss of EPB41L3 expression is commonly observed in lung cancer, breast cancer, esophageal squamous cell carcinoma and meningiomas. DNA methylation and a loss of heterozygosity have been reported to contribute to the downregulation of EPB41L3. To date, the biological functions of protein 4.1B/DAL‑1 in carcinogenesis remain unknown. The present review summarizes the current understanding of the role of protein 4.1B/DAL‑1 in cancer and highlights its potential as a cancer diagnostic and prognostic biomarker in cancer therapeutics.
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Affiliation(s)
- Xiaofeng Yuan
- Department of Orthopaedics, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - Lianhua Piao
- Institute of Bioinformatics and Medical Engineering, Jiangsu University of Technology, Changzhou, Jiangsu 213001, P.R. China
| | - Luhui Wang
- Department of Orthopaedics, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - Xu Han
- Department of Urology, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - Ming Zhuang
- Department of Orthopaedics, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - Zhiwei Liu
- Department of Orthopaedics, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
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Bonetto G, Hivert B, Goutebroze L, Karagogeos D, Crépel V, Faivre-Sarrailh C. Selective Axonal Expression of the Kv1 Channel Complex in Pre-myelinated GABAergic Hippocampal Neurons. Front Cell Neurosci 2019; 13:222. [PMID: 31164806 PMCID: PMC6535494 DOI: 10.3389/fncel.2019.00222] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/02/2019] [Indexed: 01/01/2023] Open
Abstract
In myelinated fibers, the voltage-gated sodium channels Nav1 are concentrated at the nodal gap to ensure the saltatory propagation of action potentials. The voltage-gated potassium channels Kv1 are segregated at the juxtaparanodes under the compact myelin sheath and may stabilize axonal conduction. It has been recently reported that hippocampal GABAergic neurons display high density of Nav1 channels remarkably in clusters along the axon before myelination (Freeman et al., 2015). In inhibitory neurons, the Nav1 channels are trapped by the ankyrinG scaffold at the axon initial segment (AIS) as observed in pyramidal and granule neurons, but are also forming “pre-nodes,” which may accelerate conduction velocity in pre-myelinated axons. However, the distribution of the Kv1 channels along the pre-myelinated inhibitory axons is still unknown. In the present study, we show that two subtypes of hippocampal GABAergic neurons, namely the somatostatin and parvalbumin positive cells, display a selective high expression of Kv1 channels at the AIS and all along the unmyelinated axons. These inhibitory axons are also highly enriched in molecules belonging to the juxtaparanodal Kv1 complex, including the cell adhesion molecules (CAMs) TAG-1, Caspr2, and ADAM22 and the scaffolding protein 4.1B. Here, taking advantage of hippocampal cultures from 4.1B and TAG-1 knock-out mice, we observed that 4.1B is required for the proper positioning of Caspr2 and TAG-1 along the distal axon, and that TAG-1 deficiency induces alterations in the axonal distribution of Caspr2. However, the axonal expression of Kv1 channels and clustering of ankyrinG were not modified. In conclusion, this study allowed the analysis of the hierarchy between channels, CAMs and scaffolding proteins for their expression along hippocampal inhibitory axons before myelination. The early steps of channel compartmentalization preceding myelination may be crucial for stabilizing nerve impulses switching from a continuous to saltatory conduction during network development.
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Affiliation(s)
- Giulia Bonetto
- INSERM UMR1249, Institut de Neurobiologie de la Méditerranée, Aix-Marseille Université, Marseille, France
| | - Bruno Hivert
- INSERM UMR1249, Institut de Neurobiologie de la Méditerranée, Aix-Marseille Université, Marseille, France
| | - Laurence Goutebroze
- INSERM UMR-S 1270, Institut du Fer à Moulin, Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
| | - Domna Karagogeos
- Department of Basic Sciences, Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, University of Crete Medical School - University of Crete, Heraklion, Greece
| | - Valérie Crépel
- INSERM UMR1249, Institut de Neurobiologie de la Méditerranée, Aix-Marseille Université, Marseille, France
| | - Catherine Faivre-Sarrailh
- INSERM UMR1249, Institut de Neurobiologie de la Méditerranée, Aix-Marseille Université, Marseille, France
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13
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Saifetiarova J, Bhat MA. Ablation of cytoskeletal scaffolding proteins, Band 4.1B and Whirlin, leads to cerebellar purkinje axon pathology and motor dysfunction. J Neurosci Res 2018; 97:313-331. [PMID: 30447021 DOI: 10.1002/jnr.24352] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 10/12/2018] [Accepted: 10/12/2018] [Indexed: 12/23/2022]
Abstract
The cerebellar cortex receives neural information from other brain regions to allow fine motor coordination and motor learning. The primary output neurons from the cerebellum are the Purkinje neurons that transmit inhibitory responses to deep cerebellar nuclei through their myelinated axons. Altered morphological organization and electrical properties of the Purkinje axons lead to detrimental changes in locomotor activity often leading to cerebellar ataxias. Two cytoskeletal scaffolding proteins Band 4.1B (4.1B) and Whirlin (Whrn) have been previously shown to play independent roles in axonal domain organization and maintenance in myelinated axons in the spinal cord and sciatic nerves. Immunoblot analysis had indicated cerebellar expression for both 4.1B and Whrn; however, their subcellular localization and cerebellum-specific functions have not been characterized. Using 4.1B and Whrn single and double mutant animals, we show that both proteins are expressed in common cellular compartments of the cerebellum and play cooperative roles in preservation of the integrity of Purkinje neuron myelinated axons. We demonstrate that both 4.1B and Whrn are required for the maintenance of axonal ultrastructure and health. Loss of 4.1B and Whrn leads to axonal transport defects manifested by formation of swellings containing cytoskeletal components, membranous organelles, and vesicles. Moreover, ablation of both proteins progressively affects cerebellar function with impairment in locomotor performance detected by altered gait parameters. Together, our data indicate that 4.1B and Whrn are required for maintaining proper axonal cytoskeletal organization and axonal domains, which is necessary for cerebellum-controlled fine motor coordination.
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Affiliation(s)
- Julia Saifetiarova
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, Long School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, Long School of Medicine, University of Texas Health Science Center, San Antonio, Texas
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14
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Saint-Martin M, Joubert B, Pellier-Monnin V, Pascual O, Noraz N, Honnorat J. Contactin-associated protein-like 2, a protein of the neurexin family involved in several human diseases. Eur J Neurosci 2018; 48:1906-1923. [PMID: 30028556 DOI: 10.1111/ejn.14081] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/08/2018] [Accepted: 07/02/2018] [Indexed: 12/11/2022]
Abstract
Contactin-associated protein-like 2 (CASPR2) is a cell adhesion protein of the neurexin family. Proteins of this family have been shown to play a role in the development of the nervous system, in synaptic functions, and in neurological diseases. Over recent years, CASPR2 function has gained an increasing interest as demonstrated by the growing number of publications. Here, we gather published data to comprehensively review CASPR2 functions within the nervous system in relation to CASPR2-related diseases in humans. On the one hand, studies on Cntnap2 (coding for CASPR2) knockout mice revealed its role during development, especially, in setting-up the inhibitory network. Consistent with this result, mutations in the CNTNAP2 gene coding for CASPR2 in human have been identified in neurodevelopmental disorders such as autism, intellectual disability, and epilepsy. On the other hand, CASPR2 was shown to play a role beyond development, in the localization of voltage-gated potassium channel (VGKC) complex that is composed of TAG-1, Kv1.1, and Kv1.2. This complex was found in several subcellular compartments essential for action potential propagation: the node of Ranvier, the axon initial segment, and the synapse. In line with a role of CASPR2 in the mature nervous system, neurological autoimmune diseases have been described in patients without neurodevelopmental disorders but with antibodies directed against CASPR2. These autoimmune diseases were of two types: central with memory disorders and temporal lobe seizures, or peripheral with muscular hyperactivity. Overall, we review the up-to-date knowledge on CASPR2 function and pinpoint confused or lacking information that will need further investigation.
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Affiliation(s)
- Margaux Saint-Martin
- Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Bastien Joubert
- Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France.,French Reference Center on Paraneoplastic Neurological Syndrome, Hospices Civils de Lyon, Hôpital Neurologique, Bron, France
| | - Véronique Pellier-Monnin
- Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Olivier Pascual
- Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Nelly Noraz
- Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Jérôme Honnorat
- Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France.,French Reference Center on Paraneoplastic Neurological Syndrome, Hospices Civils de Lyon, Hôpital Neurologique, Bron, France
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15
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Abstract
Vertebrate nervous systems rely on rapid nerve impulse transmission to support their complex functions. Fast conduction depends on ensheathment of nerve axons by myelin-forming glia and the clustering of high concentrations of voltage-gated sodium channels (Nav) in the axonal gaps between myelinated segments. These gaps are the nodes of Ranvier. Depolarization of the axonal membrane initiates the action potential responsible for impulse transmission, and the Nav help ensure that this is restricted to nodes. In the central nervous system, the formation of nodes and the clustering of Nav in nodal complexes is achieved when oligodendrocytes extend their processes and ultimately ensheath axons with myelin. However, the mechanistic relationship between myelination and the formation of nodal complexes is unclear. Here we review recent work in the central nervous system that shows that axons, by assembling distinct cytoskeletal interfaces, are not only active participants in oligodendrocyte process migration but are also significant contributors to the mechanisms by which myelination causes Nav clustering. We also discuss how the segregation of membrane protein complexes through their interaction with distinct cytoskeletal complexes may play a wider role in establishing surface domains in axons.
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Affiliation(s)
- Aniket Ghosh
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | - Diane L. Sherman
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | - Peter J. Brophy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
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16
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Zoupi L, Savvaki M, Kalemaki K, Kalafatakis I, Sidiropoulou K, Karagogeos D. The function of contactin-2/TAG-1 in oligodendrocytes in health and demyelinating pathology. Glia 2017; 66:576-591. [PMID: 29165835 DOI: 10.1002/glia.23266] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 10/09/2017] [Accepted: 11/02/2017] [Indexed: 12/21/2022]
Abstract
The oligodendrocyte maturation process and the transition from the pre-myelinating to the myelinating state are extremely important during development and in pathology. In the present study, we have investigated the role of the cell adhesion molecule CNTN2/TAG-1 on oligodendrocyte proliferation, differentiation, myelination, and function during development and under pathological conditions. With the combination of in vivo, in vitro, ultrastructural, and electrophysiological methods, we have mapped the expression of CNTN2 protein in the oligodendrocyte lineage during the different stages of myelination and its involvement on oligodendrocyte maturation, branching, myelin-gene expression, myelination, and axonal function. The cuprizone model of central nervous system demyelination was further used to assess CNTN2 in pathology. During development, CNTN2 can transiently affect the expression levels of myelin and myelin-regulating genes, while its absence results in reduced oligodendrocyte branching, hypomyelination of fiber tracts and impaired axonal conduction. In pathology, CNTN2 absence does not affect the extent of de- and remyelination. However during remyelination, a novel, CNTN2-independent mechanism is revealed that is able to recluster voltage gated potassium channels (VGKCs) resulting in the improvement of fiber conduction.
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Affiliation(s)
- Lida Zoupi
- Department of Basic Science, Faculty of Medicine, University of Crete, Voutes University Campus, GR-70013, P.O. Box 2208, Heraklion, Crete, Greece and 1Institute of Molecular Biology & Biotechnology -FoRTH, Nikolaou Plastira 100 GR-70013, Heraklion, Crete, Greece
| | - Maria Savvaki
- Department of Basic Science, Faculty of Medicine, University of Crete, Voutes University Campus, GR-70013, P.O. Box 2208, Heraklion, Crete, Greece and 1Institute of Molecular Biology & Biotechnology -FoRTH, Nikolaou Plastira 100 GR-70013, Heraklion, Crete, Greece
| | - Katerina Kalemaki
- Department of Basic Science, Faculty of Medicine, University of Crete, Voutes University Campus, GR-70013, P.O. Box 2208, Heraklion, Crete, Greece and 1Institute of Molecular Biology & Biotechnology -FoRTH, Nikolaou Plastira 100 GR-70013, Heraklion, Crete, Greece
| | - Ilias Kalafatakis
- Department of Basic Science, Faculty of Medicine, University of Crete, Voutes University Campus, GR-70013, P.O. Box 2208, Heraklion, Crete, Greece and 1Institute of Molecular Biology & Biotechnology -FoRTH, Nikolaou Plastira 100 GR-70013, Heraklion, Crete, Greece
| | - Kyriaki Sidiropoulou
- Neurophysiology & Behavior Laboratory, Department of Biology, University of Crete, Voutes University Campus, GR-70013, P.O. Box 2208, Heraklion, Crete, Greece
| | - Domna Karagogeos
- Department of Basic Science, Faculty of Medicine, University of Crete, Voutes University Campus, GR-70013, P.O. Box 2208, Heraklion, Crete, Greece and 1Institute of Molecular Biology & Biotechnology -FoRTH, Nikolaou Plastira 100 GR-70013, Heraklion, Crete, Greece
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17
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Pinatel D, Hivert B, Saint-Martin M, Noraz N, Savvaki M, Karagogeos D, Faivre-Sarrailh C. The Kv1-associated molecules TAG-1 and Caspr2 are selectively targeted to the axon initial segment in hippocampal neurons. J Cell Sci 2017; 130:2209-2220. [PMID: 28533267 DOI: 10.1242/jcs.202267] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 05/18/2017] [Indexed: 12/28/2022] Open
Abstract
Caspr2 and TAG-1 (also known as CNTNAP2 and CNTN2, respectively) are cell adhesion molecules (CAMs) associated with the voltage-gated potassium channels Kv1.1 and Kv1.2 (also known as KCNA1 and KCNA2, respectively) at regions controlling axonal excitability, namely, the axon initial segment (AIS) and juxtaparanodes of myelinated axons. The distribution of Kv1 at juxtaparanodes requires axo-glial contacts mediated by Caspr2 and TAG-1. In the present study, we found that TAG-1 strongly colocalizes with Kv1.2 at the AIS of cultured hippocampal neurons, whereas Caspr2 is uniformly expressed along the axolemma. Live-cell imaging revealed that Caspr2 and TAG-1 are sorted together in axonal transport vesicles. Therefore, their differential distribution may result from diffusion and trapping mechanisms induced by selective partnerships. By using deletion constructs, we identified two molecular determinants of Caspr2 that regulate its axonal positioning. First, the LNG2-EGF1 modules in the ectodomain of Caspr2, which are involved in its axonal distribution. Deletion of these modules promotes AIS localization and association with TAG-1. Second, the cytoplasmic PDZ-binding site of Caspr2, which could elicit AIS enrichment and recruitment of the membrane-associated guanylate kinase (MAGuK) protein MPP2. Hence, the selective distribution of Caspr2 and TAG-1 may be regulated, allowing them to modulate the strategic function of the Kv1 complex along axons.
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Affiliation(s)
- Delphine Pinatel
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, UMR7286, Marseille, France
| | - Bruno Hivert
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, UMR7286, Marseille, France
| | - Margaux Saint-Martin
- Institut Neuromyogène, CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Nelly Noraz
- Institut Neuromyogène, CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Maria Savvaki
- Department of Basic Sciences, University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, University of Crete, Heraklion, Greece
| | - 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 Crete, Heraklion, Greece
| | - Catherine Faivre-Sarrailh
- Aix-Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, UMR7286, Marseille, France
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18
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Brivio V, Faivre-Sarrailh C, Peles E, Sherman DL, Brophy PJ. Assembly of CNS Nodes of Ranvier in Myelinated Nerves Is Promoted by the Axon Cytoskeleton. Curr Biol 2017; 27:1068-1073. [PMID: 28318976 PMCID: PMC5387178 DOI: 10.1016/j.cub.2017.01.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 12/17/2016] [Accepted: 01/12/2017] [Indexed: 11/02/2022]
Abstract
Nodes of Ranvier in the axons of myelinated neurons are exemplars of the specialized cell surface domains typical of polarized cells. They are rich in voltage-gated sodium channels (Nav) and thus underpin rapid nerve impulse conduction in the vertebrate nervous system [1]. Although nodal proteins cluster in response to myelination, how myelin-forming glia influence nodal assembly is poorly understood. An axoglial adhesion complex comprising glial Neurofascin155 and axonal Caspr/Contactin flanks mature nodes [2]. We have shown that assembly of this adhesion complex at the extremities of migrating oligodendroglial processes promotes process convergence along the axon during central nervous system (CNS) node assembly [3]. Here we show that anchorage of this axoglial complex to the axon cytoskeleton is essential for efficient CNS node formation. When anchorage is disrupted, both the adaptor Protein 4.1B and the cytoskeleton protein βII spectrin are mislocalized in the axon, and assembly of the node of Ranvier is significantly delayed. Nodal proteins and migrating oligodendroglial processes are no longer juxtaposed, and single detached nodal complexes replace the symmetrical heminodes found in both the CNS and peripheral nervous system (PNS) during development. We propose that axoglial adhesion complexes contribute to the formation of an interface between cytoskeletal elements enriched in Protein 4.1B and βII spectrin and those enriched in nodal ankyrinG and βIV spectrin. This clusters nascent nodal complexes at heminodes and promotes their timely coalescence to form the mature node of Ranvier. These data demonstrate a role for the axon cytoskeleton in the assembly of a critical neuronal domain, the node of Ranvier.
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Affiliation(s)
- Veronica Brivio
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Catherine Faivre-Sarrailh
- Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille-UMR 7286, CNRS, 13344 Marseille, France
| | - Elior Peles
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Diane L Sherman
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Peter J Brophy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK.
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19
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Saifetiarova J, Liu X, Taylor AM, Li J, Bhat MA. Axonal domain disorganization in Caspr1 and Caspr2 mutant myelinated axons affects neuromuscular junction integrity, leading to muscle atrophy. J Neurosci Res 2017; 95:1373-1390. [PMID: 28370195 DOI: 10.1002/jnr.24052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 02/14/2017] [Accepted: 02/24/2017] [Indexed: 12/19/2022]
Abstract
Bidirectional interactions between neurons and myelinating glial cells result in formation of axonal domains along myelinated fibers. Loss of axonal domains leads to detrimental consequences on nerve structure and function, resulting in reduced conductive properties and the diminished ability to reliably transmit signals to the targets they innervate. Thus, impairment of peripheral myelinated axons that project to the surface of muscle fibers and form neuromuscular junction (NMJ) synapses leads to muscle dysfunction. The goal of our studies was to determine how altered electrophysiological properties due to axonal domain disorganization lead to muscle pathology, which is relevant to a variety of peripheral neuropathies, demyelinating diseases, and neurodegenerative disorders. Using conventional Contactin-Associated Protein 1 (Caspr1) and Caspr2 single or double mutants with disrupted paranodal, juxtaparanodal, or both regions, respectively, in peripheral myelinated axons, we correlated defects in NMJ integrity and muscle pathology. Our data show that loss of axonal domains in Caspr1 and Caspr2 single and double mutants primarily alters distal myelinated fibers together with presynaptic terminals, eventually leading to NMJ denervation and reduction in postsynaptic endplate areas. Moreover, reduction in conductive properties of peripheral myelinated fibers together with NMJ disintegration leads to muscle atrophy in Caspr1 mutants or muscle fiber degeneration accompanied by mitochondrial dysfunction in Caspr1/Caspr2 double mutants. Together, our data indicate that proper organization of axonal domains in myelinated fibers is critical for optimal propagation of electrical signals, NMJ integrity, and muscle health, and provide insights into a wide range of pathologies that result in reduced nerve conduction leading to muscle atrophy. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Julia Saifetiarova
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Xi Liu
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas.,Xiangya School of Medicine, Central South University, Changsha, China
| | - Anna M Taylor
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Jie Li
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center, San Antonio, Texas
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20
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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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21
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Martin PM, Cifuentes-Diaz C, Devaux J, Garcia M, Bureau J, Thomasseau S, Klingler E, Girault JA, Goutebroze L. Schwannomin-interacting Protein 1 Isoform IQCJ-SCHIP1 Is a Multipartner Ankyrin- and Spectrin-binding Protein Involved in the Organization of Nodes of Ranvier. J Biol Chem 2016; 292:2441-2456. [PMID: 27979964 DOI: 10.1074/jbc.m116.758029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 12/14/2016] [Indexed: 11/06/2022] Open
Abstract
The nodes of Ranvier are essential regions for action potential conduction in myelinated fibers. They are enriched in multimolecular complexes composed of voltage-gated Nav and Kv7 channels associated with cell adhesion molecules. Cytoskeletal proteins ankyrin-G (AnkG) and βIV-spectrin control the organization of these complexes and provide mechanical support to the plasma membrane. IQCJ-SCHIP1 is a cytoplasmic protein present in axon initial segments and nodes of Ranvier. It interacts with AnkG and is absent from nodes and axon initial segments of βIV-spectrin and AnkG mutant mice. Here, we show that IQCJ-SCHIP1 also interacts with βIV-spectrin and Kv7.2/3 channels and self-associates, suggesting a scaffolding role in organizing nodal proteins. IQCJ-SCHIP1 binding requires a βIV-spectrin-specific domain and Kv7 channel 1-5-10 calmodulin-binding motifs. We then investigate the role of IQCJ-SCHIP1 in vivo by studying peripheral myelinated fibers in Schip1 knock-out mutant mice. The major nodal proteins are normally enriched at nodes in these mice, indicating that IQCJ-SCHIP1 is not required for their nodal accumulation. However, morphometric and ultrastructural analyses show an altered shape of nodes similar to that observed in βIV-spectrin mutant mice, revealing that IQCJ-SCHIP1 contributes to nodal membrane-associated cytoskeleton organization, likely through its interactions with the AnkG/βIV-spectrin network. Our work reveals that IQCJ-SCHIP1 interacts with several major nodal proteins, and we suggest that it contributes to a higher organizational level of the AnkG/βIV-spectrin network critical for node integrity.
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Affiliation(s)
- Pierre-Marie Martin
- From INSERM, UMR-S 839, F-75005 Paris.,the Université Pierre et Marie Curie (UPMC)-Sorbonne Universités, UMR-S 839, 75005 Paris.,the Institut du Fer à Moulin, 75005 Paris, and
| | - Carmen Cifuentes-Diaz
- From INSERM, UMR-S 839, F-75005 Paris.,the Université Pierre et Marie Curie (UPMC)-Sorbonne Universités, UMR-S 839, 75005 Paris.,the Institut du Fer à Moulin, 75005 Paris, and
| | - Jérôme Devaux
- the Aix Marseille University, CNRS, CRN2M, 13344 Marseille, France
| | - Marta Garcia
- From INSERM, UMR-S 839, F-75005 Paris.,the Université Pierre et Marie Curie (UPMC)-Sorbonne Universités, UMR-S 839, 75005 Paris.,the Institut du Fer à Moulin, 75005 Paris, and
| | - Jocelyne Bureau
- From INSERM, UMR-S 839, F-75005 Paris.,the Université Pierre et Marie Curie (UPMC)-Sorbonne Universités, UMR-S 839, 75005 Paris.,the Institut du Fer à Moulin, 75005 Paris, and
| | - Sylvie Thomasseau
- From INSERM, UMR-S 839, F-75005 Paris.,the Université Pierre et Marie Curie (UPMC)-Sorbonne Universités, UMR-S 839, 75005 Paris.,the Institut du Fer à Moulin, 75005 Paris, and
| | - Esther Klingler
- From INSERM, UMR-S 839, F-75005 Paris.,the Université Pierre et Marie Curie (UPMC)-Sorbonne Universités, UMR-S 839, 75005 Paris.,the Institut du Fer à Moulin, 75005 Paris, and
| | - Jean-Antoine Girault
- From INSERM, UMR-S 839, F-75005 Paris.,the Université Pierre et Marie Curie (UPMC)-Sorbonne Universités, UMR-S 839, 75005 Paris.,the Institut du Fer à Moulin, 75005 Paris, and
| | - Laurence Goutebroze
- the Université Pierre et Marie Curie (UPMC)-Sorbonne Universités, UMR-S 839, 75005 Paris, .,the Institut du Fer à Moulin, 75005 Paris, and
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22
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Chen MS, Kim H, Jagot-Lacoussiere L, Maurel P. Cadm3 (Necl-1) interferes with the activation of the PI3 kinase/Akt signaling cascade and inhibits Schwann cell myelination in vitro. Glia 2016; 64:2247-2262. [PMID: 27658374 DOI: 10.1002/glia.23072] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 08/10/2016] [Accepted: 09/08/2016] [Indexed: 11/06/2022]
Abstract
Axo-glial interactions are critical for myelination and the domain organization of myelinated fibers. Cell adhesion molecules belonging to the Cadm family, and in particular Cadm3 (axonal) and its heterophilic binding partner Cadm4 (Schwann cell), mediate these interactions along the internode. Using targeted shRNA-mediated knockdown, we show that the removal of axonal Cadm3 promotes Schwann cell myelination in the in vitro DRG neuron/Schwann cell myelinating system. Conversely, over-expressing Cadm3 on the surface of DRG neuron axons results in an almost complete inability by Schwann cells to form myelin segments. Axons of superior cervical ganglion (SCG) neurons, which do not normally support the formation of myelin segments by Schwann cells, express higher levels of Cadm3 compared to DRG neurons. Knocking down Cadm3 in SCG neurons promotes myelination. Finally, the extracellular domain of Cadm3 interferes in a dose-dependent manner with the activation of ErbB3 and of the pro-myelinating PI3K/Akt pathway, but does not interfere with the activation of the Mek/Erk1/2 pathway. While not in direct contradiction, these in vitro results shed lights on the apparent lack of phenotype that was reported from in vivo studies of Cadm3-/- mice. Our results suggest that Cadm3 may act as a negative regulator of PNS myelination, potentially through the selective regulation of the signaling cascades activated in Schwann cells by axonal contact, and in particular by type III Nrg-1. Further analyses of peripheral nerves in the Cadm-/- mice will be needed to determine the exact role of axonal Cadm3 in PNS myelination. GLIA 2016;64:2247-2262.
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Affiliation(s)
- Ming-Shuo Chen
- Department of Biological Sciences, Rutgers, The State University of New Jersey, Newark, New Jersey
| | - Hyosung Kim
- Department of Biological Sciences, Rutgers, The State University of New Jersey, Newark, New Jersey
| | | | - Patrice Maurel
- Department of Biological Sciences, Rutgers, The State University of New Jersey, Newark, New Jersey.
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23
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Abstract
Myelinated axons are divided into polarized subdomains including axon initial segments and nodes of Ranvier. These domains initiate and propagate action potentials and regulate the trafficking and localization of somatodendritic and axonal proteins. Formation of axon initial segments and nodes of Ranvier depends on intrinsic (neuronal) and extrinsic (glial) interactions. Several levels of redundancy in both mechanisms and molecules also exist to ensure efficient node formation. Furthermore, the establishment of polarized domains at and near nodes of Ranvier reflects the intrinsic polarity of the myelinating glia responsible for node assembly. Here, we discuss the various polarized domains of myelinated axons, how they are established by both intrinsic and extrinsic interactions, and the polarity of myelinating glia.
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Affiliation(s)
- Daniel R Zollinger
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030;
| | - Kelli L Baalman
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030;
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030;
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24
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Leshchyns'ka I, Sytnyk V. Reciprocal Interactions between Cell Adhesion Molecules of the Immunoglobulin Superfamily and the Cytoskeleton in Neurons. Front Cell Dev Biol 2016; 4:9. [PMID: 26909348 PMCID: PMC4754453 DOI: 10.3389/fcell.2016.00009] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 02/01/2016] [Indexed: 12/04/2022] Open
Abstract
Cell adhesion molecules of the immunoglobulin superfamily (IgSF) including the neural cell adhesion molecule (NCAM) and members of the L1 family of neuronal cell adhesion molecules play important functions in the developing nervous system by regulating formation, growth and branching of neurites, and establishment of the synaptic contacts between neurons. In the mature brain, members of IgSF regulate synapse composition, function, and plasticity required for learning and memory. The intracellular domains of IgSF cell adhesion molecules interact with the components of the cytoskeleton including the submembrane actin-spectrin meshwork, actin microfilaments, and microtubules. In this review, we summarize current data indicating that interactions between IgSF cell adhesion molecules and the cytoskeleton are reciprocal, and that while IgSF cell adhesion molecules regulate the assembly of the cytoskeleton, the cytoskeleton plays an important role in regulation of the functions of IgSF cell adhesion molecules. Reciprocal interactions between NCAM and L1 family members and the cytoskeleton and their role in neuronal differentiation and synapse formation are discussed in detail.
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Affiliation(s)
- Iryna Leshchyns'ka
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia
| | - Vladimir Sytnyk
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia
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25
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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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26
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Freeman SA, Desmazières A, Fricker D, Lubetzki C, Sol-Foulon N. Mechanisms of sodium channel clustering and its influence on axonal impulse conduction. Cell Mol Life Sci 2016; 73:723-35. [PMID: 26514731 PMCID: PMC4735253 DOI: 10.1007/s00018-015-2081-1] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 10/21/2015] [Accepted: 10/22/2015] [Indexed: 12/16/2022]
Abstract
The efficient propagation of action potentials along nervous fibers is necessary for animals to interact with the environment with timeliness and precision. Myelination of axons is an essential step to ensure fast action potential propagation by saltatory conduction, a process that requires highly concentrated voltage-gated sodium channels at the nodes of Ranvier. Recent studies suggest that the clustering of sodium channels can influence axonal impulse conduction in both myelinated and unmyelinated fibers, which could have major implications in disease, particularly demyelinating pathology. This comprehensive review summarizes the mechanisms governing the clustering of sodium channels at the peripheral and central nervous system nodes and the specific roles of their clustering in influencing action potential conduction. We further highlight the classical biophysical parameters implicated in conduction timing, followed by a detailed discussion on how sodium channel clustering along unmyelinated axons can impact axonal impulse conduction in both physiological and pathological contexts.
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Affiliation(s)
- Sean A Freeman
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
| | - Anne Desmazières
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
| | - Desdemona Fricker
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
| | - Catherine Lubetzki
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
- Assistance Publique-Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Paris, France.
| | - Nathalie Sol-Foulon
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
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Susuki K, Otani Y, Rasband MN. Submembranous cytoskeletons stabilize nodes of Ranvier. Exp Neurol 2016; 283:446-51. [PMID: 26775177 DOI: 10.1016/j.expneurol.2015.11.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 11/10/2015] [Accepted: 11/23/2015] [Indexed: 01/22/2023]
Abstract
Rapid action potential propagation along myelinated axons requires voltage-gated Na(+) (Nav) channel clustering at nodes of Ranvier. At paranodes flanking nodes, myelinating glial cells interact with axons to form junctions. The regions next to the paranodes called juxtaparanodes are characterized by high concentrations of voltage-gated K(+) channels. Paranodal axoglial junctions function as barriers to restrict the position of these ion channels. These specialized domains along the myelinated nerve fiber are formed by multiple molecular mechanisms including interactions between extracellular matrix, cell adhesion molecules, and cytoskeletal scaffolds. This review highlights recent findings into the roles of submembranous cytoskeletal proteins in the stabilization of molecular complexes at and near nodes. Axonal ankyrin-spectrin complexes stabilize Nav channels at nodes. Axonal protein 4.1B-spectrin complexes contribute to paranode and juxtaparanode organization. Glial ankyrins enriched at paranodes facilitate node formation. Finally, disruption of spectrins or ankyrins by genetic mutations or proteolysis is involved in the pathophysiology of various neurological or psychiatric disorders.
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Affiliation(s)
- Keiichiro Susuki
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, United States.
| | - Yoshinori Otani
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, United States
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States.
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Pinatel D, Hivert B, Boucraut J, Saint-Martin M, Rogemond V, Zoupi L, Karagogeos D, Honnorat J, Faivre-Sarrailh C. Inhibitory axons are targeted in hippocampal cell culture by anti-Caspr2 autoantibodies associated with limbic encephalitis. Front Cell Neurosci 2015. [PMID: 26217189 PMCID: PMC4496579 DOI: 10.3389/fncel.2015.00265] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Contactin-associated protein-like 2 (Caspr2), also known as CNTNAP2, is a cell adhesion molecule that clusters voltage-gated potassium channels (Kv1.1/1.2) at the juxtaparanodes of myelinated axons and may regulate axonal excitability. As a component of the Kv1 complex, Caspr2 has been identified as a target in neuromyotonia and Morvan syndrome, but also in some cases of autoimmune limbic encephalitis (LE). How anti-Caspr2 autoimmunity is linked with the central neurological symptoms is still elusive. In the present study, using anti-Caspr2 antibodies from seven patients affected by pure LE, we determined that IgGs in the cerebrospinal fluid of four out seven patients were selectively directed against the N-terminal Discoïdin and LamininG1 modules of Caspr2. Using live immunolabeling of cultured hippocampal neurons, we determined that serum IgGs in all patients strongly targeted inhibitory interneurons. Caspr2 was highly detected on GAD65-positive axons that are surrounding the cell bodies and at the VGAT-positive inhibitory presynaptic contacts. Functional assays indicated that LE autoantibodies may induce alteration of Gephyrin clusters at inhibitory synaptic contacts. Next, we generated a Caspr2-Fc chimera to reveal Caspr2 receptors on hippocampal neurons localized at the somato-dendritic compartment and post-synapse. Caspr2-Fc binding was strongly increased on TAG-1-transfected neurons and conversely, Caspr2-Fc did not bind hippocampal neurons from TAG-1-deficient mice. Our data indicate that Caspr2 may participate as a cell recognition molecule in the dynamics of inhibitory networks. This study provides new insight into the potential pathogenic effect of anti-Caspr2 autoantibodies in central hyperexcitability that may be related with perturbation of inhibitory interneuron activity.
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Affiliation(s)
- Delphine Pinatel
- Aix Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, CRN2M-UMR7286, Faculté de Médecine Nord Marseille, France
| | - Bruno Hivert
- Aix Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, CRN2M-UMR7286, Faculté de Médecine Nord Marseille, France
| | - José Boucraut
- Aix Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, CRN2M-UMR7286, Faculté de Médecine Nord Marseille, France ; Laboratoire d'Immunologie et d'Immunopathologie, AP-HM, Hôpital de la Conception Marseille, France
| | - Margaux Saint-Martin
- French Reference Center on Paraneoplastic Neurological Syndrome, Hospices Civils de Lyon, Hôpital Neurologique Bron, France ; INSERM U1028 - CNRS UMR 5292, Lyon Neuroscience Research Center Lyon, France ; Université de Lyon - Université Claude Bernard Lyon 1 Lyon, France
| | - Véronique Rogemond
- French Reference Center on Paraneoplastic Neurological Syndrome, Hospices Civils de Lyon, Hôpital Neurologique Bron, France ; INSERM U1028 - CNRS UMR 5292, Lyon Neuroscience Research Center Lyon, France ; Université de Lyon - Université Claude Bernard Lyon 1 Lyon, France
| | - Lida Zoupi
- Institute of Molecular Biology and Biotechnology - Foundation for Research and Technology, University of Crete Heraklion, Greece
| | - Domna Karagogeos
- Institute of Molecular Biology and Biotechnology - Foundation for Research and Technology, University of Crete Heraklion, Greece
| | - Jérôme Honnorat
- French Reference Center on Paraneoplastic Neurological Syndrome, Hospices Civils de Lyon, Hôpital Neurologique Bron, France ; INSERM U1028 - CNRS UMR 5292, Lyon Neuroscience Research Center Lyon, France ; Université de Lyon - Université Claude Bernard Lyon 1 Lyon, France
| | - Catherine Faivre-Sarrailh
- Aix Marseille Université, CNRS, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, CRN2M-UMR7286, Faculté de Médecine Nord Marseille, France
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Chen X, Guan X, Zhang H, Xie X, Wang H, Long J, Cai T, Li S, Liu Z, Zhang Y. DAL-1 attenuates epithelial-to mesenchymal transition in lung cancer. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2015; 34:3. [PMID: 25609022 PMCID: PMC4307741 DOI: 10.1186/s13046-014-0117-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Accepted: 12/22/2014] [Indexed: 02/06/2023]
Abstract
BACKGROUND Epithelial-to mesenchymal transition (EMT) involves in metastasis, causing loss of epithelial polarity. Metastasis is the major cause of carcinoma-induced death, but mechanisms are poorly understood. Here we identify differentially expressed in adenocarcinoma of the lung-1 (DAL-1), a protein belongs to the membrane-associated cytoskeleton protein 4.1 family, as an efficient suppressor of EMT in lung cancer. METHODS The relationship between DAL-1 and EMT markers were analyzed by using immunohistochemistry in the clinical lung cancer tissues. Quantitative real-time PCR and western blot were used to characterize the expression of the EMT indicator mRNAs and proteins in DAL-1 overexpressed or knockdown cells. DAL-1 combined proteins were assessed by co-immunoprecipitation. RESULTS DAL-1 levels were strongly reduced even lost in lymph node metastasis and advanced pathological stage of human lung carcinomas. Overexpression of DAL-1 altered the expression of numerous EMT markers, such as E-cadherin, β-catenin Vimentin and N-cadherin expression, meanwhile changed the morphological shape of lung cancer cells, and whereas silencing DAL-1 had an opposite effect. DAL-1 directly combined with E-cadherin promoter and regulated its expression that could be the reason for impairing EMT and decreasing cell migration and invasion. Strikingly, HSPA5 was found as DAL-1 direct binding protein. CONCLUSIONS These results suggest that tumor suppressor DAL-1 could also attenuate EMT and be important for tumor metastasis in the early transformation process in lung cancer.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Yajie Zhang
- Department of Pathology, School of Basic Medical Science, Guangzhou Medical University, 195# Dongfeng West Road, Guangzhou 510180, Guangdong, People's Republic of China.
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30
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Chang KJ, Zollinger DR, Susuki K, Sherman DL, Makara MA, Brophy PJ, Cooper EC, Bennett V, Mohler PJ, Rasband MN. Glial ankyrins facilitate paranodal axoglial junction assembly. Nat Neurosci 2014; 17:1673-81. [PMID: 25362471 PMCID: PMC4260775 DOI: 10.1038/nn.3858] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 10/08/2014] [Indexed: 02/07/2023]
Abstract
Neuron-glia interactions establish functional membrane domains along myelinated axons. These include nodes of Ranvier, paranodal axoglial junctions and juxtaparanodes. Paranodal junctions are the largest vertebrate junctional adhesion complex, and they are essential for rapid saltatory conduction and contribute to assembly and maintenance of nodes. However, the molecular mechanisms underlying paranodal junction assembly are poorly understood. Ankyrins are cytoskeletal scaffolds traditionally associated with Na(+) channel clustering in neurons and are important for membrane domain establishment and maintenance in many cell types. Here we show that ankyrin-B, expressed by Schwann cells, and ankyrin-G, expressed by oligodendrocytes, are highly enriched at the glial side of paranodal junctions where they interact with the essential glial junctional component neurofascin 155. Conditional knockout of ankyrins in oligodendrocytes disrupts paranodal junction assembly and delays nerve conduction during early development in mice. Thus, glial ankyrins function as major scaffolds that facilitate early and efficient paranodal junction assembly in the developing CNS.
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Affiliation(s)
- Kae-Jiun Chang
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Daniel R. Zollinger
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Keiichiro Susuki
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Diane L. Sherman
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom EH16 4SB
| | - Michael A. Makara
- Departments of Physiology and Cell Biology, Medicine, and the Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Peter J. Brophy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom EH16 4SB
| | - Edward C. Cooper
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Vann Bennett
- Department of Cell Biology, Duke University, Durham, NC 27710, USA
| | - Peter J. Mohler
- Departments of Physiology and Cell Biology, Medicine, and the Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Matthew N. Rasband
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
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31
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Wang Z, Zhang J, Ye M, Zhu M, Zhang B, Roy M, Liu J, An X. Tumor suppressor role of protein 4.1B/DAL-1. Cell Mol Life Sci 2014; 71:4815-30. [PMID: 25183197 PMCID: PMC11113756 DOI: 10.1007/s00018-014-1707-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 07/21/2014] [Accepted: 08/15/2014] [Indexed: 12/14/2022]
Abstract
Protein 4.1B/DAL-1 is a membrane skeletal protein that belongs to the protein 4.1 family. Protein 4.1B/DAL-1 is localized to sites of cell-cell contact and functions as an adapter protein, linking the plasma membrane to the cytoskeleton or associated cytoplasmic signaling effectors and facilitating their activities in various pathways. Protein 4.1B/DAL-1 is involved in various cytoskeleton-associated processes, such as cell motility and adhesion. Moreover, protein 4.1B/DAL-1 also plays a regulatory role in cell growth, differentiation, and the establishment of epithelial-like cell structures. Protein 4.1B/DAL-1 is normally expressed in multiple human tissues, but loss of its expression or prominent down-regulation of its expression is frequently observed in corresponding tumor tissues and tumor cell lines, suggesting that protein 4.1B/DAL-1 is involved in the molecular pathogenesis of these tumors and acts as a potential tumor suppressor. This review will focus on the structure of protein 4.1B/DAL-1, 4.1B/DAL-1-interacting molecules, 4.1B/DAL-1 inactivation and tumor progression, and anti-tumor activity of the 4.1B/DAL-1.
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Affiliation(s)
- Zi Wang
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
| | - Ji Zhang
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
- Department of Hematology, The First Affiliated Hospital, University of South China, Hengyang, 421001 China
| | - Mao Ye
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan University, Changsha, 410082 China
| | - Min Zhu
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
| | - Bin Zhang
- Department of Histology and Embryology, Xiangya School Medicine, Central South University, Changsha, 410083 China
| | - Mridul Roy
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
| | - Jing Liu
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
- State Key Laboratory of Medical Genetics, Central South University, 110 Xiangya Road, Changsha, 410078 China
| | - Xiuli An
- Laboratory of Membrane Biology, New York Blood Center, 310 E 67th Street, New York, 10065 USA
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32
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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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33
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The node of Ranvier in CNS pathology. Acta Neuropathol 2014; 128:161-75. [PMID: 24913350 PMCID: PMC4102831 DOI: 10.1007/s00401-014-1305-z] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 05/27/2014] [Accepted: 05/27/2014] [Indexed: 12/11/2022]
Abstract
Healthy nodes of Ranvier are crucial for action potential propagation along myelinated axons, both in the central and in the peripheral nervous system. Surprisingly, the node of Ranvier has often been neglected when describing CNS disorders, with most pathologies classified simply as being due to neuronal defects in the grey matter or due to oligodendrocyte damage in the white matter. However, recent studies have highlighted changes that occur in pathological conditions at the node of Ranvier, and at the associated paranodal and juxtaparanodal regions where neurons and myelinating glial cells interact. Lengthening of the node of Ranvier, failure of the electrically resistive seal between the myelin and the axon at the paranode, and retraction of myelin to expose voltage-gated K+ channels in the juxtaparanode, may contribute to altering the function of myelinated axons in a wide range of diseases, including stroke, spinal cord injury and multiple sclerosis. Here, we review the principles by which the node of Ranvier operates and its molecular structure, and thus explain how defects at the node and paranode contribute to neurological disorders.
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34
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Baines AJ, Lu HC, Bennett PM. The Protein 4.1 family: hub proteins in animals for organizing membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1838:605-19. [PMID: 23747363 DOI: 10.1016/j.bbamem.2013.05.030] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 05/22/2013] [Accepted: 05/28/2013] [Indexed: 01/10/2023]
Abstract
Proteins of the 4.1 family are characteristic of eumetazoan organisms. Invertebrates contain single 4.1 genes and the Drosophila model suggests that 4.1 is essential for animal life. Vertebrates have four paralogues, known as 4.1R, 4.1N, 4.1G and 4.1B, which are additionally duplicated in the ray-finned fish. Protein 4.1R was the first to be discovered: it is a major mammalian erythrocyte cytoskeletal protein, essential to the mechanochemical properties of red cell membranes because it promotes the interaction between spectrin and actin in the membrane cytoskeleton. 4.1R also binds certain phospholipids and is required for the stable cell surface accumulation of a number of erythrocyte transmembrane proteins that span multiple functional classes; these include cell adhesion molecules, transporters and a chemokine receptor. The vertebrate 4.1 proteins are expressed in most tissues, and they are required for the correct cell surface accumulation of a very wide variety of membrane proteins including G-Protein coupled receptors, voltage-gated and ligand-gated channels, as well as the classes identified in erythrocytes. Indeed, such large numbers of protein interactions have been mapped for mammalian 4.1 proteins, most especially 4.1R, that it appears that they can act as hubs for membrane protein organization. The range of critical interactions of 4.1 proteins is reflected in disease relationships that include hereditary anaemias, tumour suppression, control of heartbeat and nervous system function. The 4.1 proteins are defined by their domain structure: apart from the spectrin/actin-binding domain they have FERM and FERM-adjacent domains and a unique C-terminal domain. Both the FERM and C-terminal domains can bind transmembrane proteins, thus they have the potential to be cross-linkers for membrane proteins. The activity of the FERM domain is subject to multiple modes of regulation via binding of regulatory ligands, phosphorylation of the FERM associated domain and differential mRNA splicing. Finally, the spectrum of interactions of the 4.1 proteins overlaps with that of another membrane-cytoskeleton linker, ankyrin. Both ankyrin and 4.1 link to the actin cytoskeleton via spectrin, and we hypothesize that differential regulation of 4.1 proteins and ankyrins allows highly selective control of cell surface protein accumulation and, hence, function. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé
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Affiliation(s)
| | - Hui-Chun Lu
- Randall Division of Cell and Molecular Biophysics, King's College London, UK
| | - Pauline M Bennett
- Randall Division of Cell and Molecular Biophysics, King's College London, UK.
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35
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Palmoplantar keratoderma along with neuromuscular and metabolic phenotypes in Slurp1-deficient mice. J Invest Dermatol 2014; 134:1589-1598. [PMID: 24499735 PMCID: PMC4214150 DOI: 10.1038/jid.2014.19] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 12/03/2013] [Accepted: 12/07/2013] [Indexed: 01/11/2023]
Abstract
Mutations in SLURP1 cause mal de Meleda, a rare palmoplantar keratoderma (PPK). SLURP1 is a secreted protein that is expressed highly in keratinocytes but has also been identified elsewhere (e.g., spinal cord neurons). Here, we examined Slurp1-deficient mice (Slurp1−/−) created by replacing exon 2 with β-gal and neo cassettes. Slurp1−/− mice developed severe PPK characterized by increased keratinocyte proliferation, an accumulation of lipid droplets in the stratum corneum, and a water barrier defect. In addition, Slurp1−/− mice exhibited reduced adiposity, protection from obesity on a high-fat diet, low plasma lipid levels, and a neuromuscular abnormality (hind limb clasping). Initially, it was unclear whether the metabolic and neuromuscular phenotypes were due to Slurp1 deficiency because we found that the targeted Slurp1 mutation reduced the expression of several neighboring genes (e.g., Slurp2, Lypd2). We therefore created a new line of knockout mice (Slurp1X−/− mice) with a simple nonsense mutation in exon 2. The Slurp1X mutation did not reduce the expression of adjacent genes, but Slurp1X−/− mice exhibited all of the phenotypes observed in the original line of knockout mice. Thus, Slurp1 deficiency in mice elicits metabolic and neuromuscular abnormalities in addition to PPK.
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Abstract
A membrane barrier important for assembly of the nodes of Ranvier is found at the paranodal junction. This junction is comprised of axonal and glial adhesion molecules linked to the axonal actin–spectrin membrane cytoskeleton through specific adaptors. In this issue, Zhang et al. (2013. J. Cell Biol.http://dx.doi.org/10.1083/jcb.201308116) show that axonal βII spectrin maintains the diffusion barrier at the paranodal junction. Thus, βII spectrin serves to compartmentalize the membrane of myelinated axons at specific locations that are determined either intrinsically (i.e., at the axonal initial segment), or by axoglial contacts (i.e., at the paranodal junction).
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Affiliation(s)
- Yael Eshed-Eisenbach
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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Wang J, Song J, An C, Dong W, Zhang J, Yin C, Hale J, Baines AJ, Mohandas N, An X. A 130-kDa protein 4.1B regulates cell adhesion, spreading, and migration of mouse embryo fibroblasts by influencing actin cytoskeleton organization. J Biol Chem 2013; 289:5925-37. [PMID: 24381168 DOI: 10.1074/jbc.m113.516617] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Protein 4.1B is a member of protein 4.1 family, adaptor proteins at the interface of membranes and the cytoskeleton. It is expressed in most mammalian tissues and is known to be required in formation of nervous and cardiac systems; it is also a tumor suppressor with a role in metastasis. Here, we explore functions of 4.1B using primary mouse embryonic fibroblasts (MEF) derived from wild type and 4.1B knock-out mice. MEF cells express two 4.1B isoforms: 130 and 60-kDa. 130-kDa 4.1B was absent from 4.1B knock-out MEF cells, but 60-kDa 4.1B remained, suggesting incomplete knock-out. Although the 130-kDa isoform was predominantly located at the plasma membrane, the 60-kDa isoform was enriched in nuclei. 130-kDa-deficient 4.1B MEF cells exhibited impaired cell adhesion, spreading, and migration; they also failed to form actin stress fibers. Impaired cell spreading and stress fiber formation were rescued by re-expression of the 130-kDa 4.1B but not the 60-kDa 4.1B. Our findings document novel, isoform-selective roles for 130-kDa 4.1B in adhesion, spreading, and migration of MEF cells by affecting actin organization, giving new insight into 4.1B functions in normal tissues as well as its role in cancer.
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Affiliation(s)
- Jie Wang
- From the Department of Biophysics, Peking University Health Science Center, Xueyuan Road, Haidian District, Beijing 100191, China
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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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Eshed-Eisenbach Y, Peles E. The making of a node: a co-production of neurons and glia. Curr Opin Neurobiol 2013; 23:1049-56. [PMID: 23831261 DOI: 10.1016/j.conb.2013.06.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 06/11/2013] [Indexed: 01/24/2023]
Abstract
Nodes of Ranvier are specialized axonal domains formed in response to a glial signal. Recent research advances have revealed that both CNS and PNS nodes form by several overlapping molecular mechanisms. However, the precise nature of these mechanisms and the hierarchy existing between them is considerably different in CNS versus PNS nodes. Namely, the Schwann cells of the PNS, which directly contact the nodal axolemma, secrete proteins that cluster axonodal components at the edges of the growing myelin segment. In contrast, the formation of CNS nodes, which are not contacted by the myelinating glia, is surprisingly similar to the assembly of the axon initial segment and depends largely on axonal diffusion barriers.
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Affiliation(s)
- Yael Eshed-Eisenbach
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel
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Buttermore ED, Thaxton CL, Bhat MA. Organization and maintenance of molecular domains in myelinated axons. J Neurosci Res 2013; 91:603-22. [PMID: 23404451 DOI: 10.1002/jnr.23197] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 09/19/2012] [Accepted: 11/28/2012] [Indexed: 01/17/2023]
Abstract
Over a century ago, Ramon y Cajal first proposed the idea of a directionality involved in nerve conduction and neuronal communication. Decades later, it was discovered that myelin, produced by glial cells, insulated axons with periodic breaks where nodes of Ranvier (nodes) form to allow for saltatory conduction. In the peripheral nervous system (PNS), Schwann cells are the glia that can either individually myelinate the axon from one neuron or ensheath axons of many neurons. In the central nervous system (CNS), oligodendrocytes are the glia that myelinate axons from different neurons. Review of more recent studies revealed that this myelination created polarized domains adjacent to the nodes. However, the molecular mechanisms responsible for the organization of axonal domains are only now beginning to be elucidated. The molecular domains in myelinated axons include the axon initial segment (AIS), where various ion channels are clustered and action potentials are initiated; the node, where sodium channels are clustered and action potentials are propagated; the paranode, where myelin loops contact with the axolemma; the juxtaparanode (JXP), where delayed-rectifier potassium channels are clustered; and the internode, where myelin is compactly wrapped. Each domain contains a unique subset of proteins critical for the domain's function. However, the roles of these proteins in axonal domain organization are not fully understood. In this review, we highlight recent advances on the molecular nature and functions of some of the components of each axonal domain and their roles in axonal domain organization and maintenance for proper neuronal communication.
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Affiliation(s)
- Elizabeth D Buttermore
- Curriculum in Neurobiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
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Systems genetics implicates cytoskeletal genes in oocyte control of cloned embryo quality. Genetics 2013; 193:877-96. [PMID: 23307892 DOI: 10.1534/genetics.112.148866] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Cloning by somatic cell nuclear transfer is an important technology, but remains limited due to poor rates of success. Identifying genes supporting clone development would enhance our understanding of basic embryology, improve applications of the technology, support greater understanding of establishing pluripotent stem cells, and provide new insight into clinically important determinants of oocyte quality. For the first time, a systems genetics approach was taken to discover genes contributing to the ability of an oocyte to support early cloned embryo development. This identified a primary locus on mouse chromosome 17 and potential loci on chromosomes 1 and 4. A combination of oocyte transcriptome profiling data, expression correlation analysis, and functional and network analyses yielded a short list of likely candidate genes in two categories. The major category-including two genes with the strongest genetic associations with the traits (Epb4.1l3 and Dlgap1)-encodes proteins associated with the subcortical cytoskeleton and other cytoskeletal elements such as the spindle. The second category encodes chromatin and transcription regulators (Runx1t1, Smchd1, and Chd7). Smchd1 promotes X chromosome inactivation, whereas Chd7 regulates expression of pluripotency genes. Runx1t1 has not been associated with these processes, but acts as a transcriptional repressor. The finding that cytoskeleton-associated proteins may be key determinants of early clone development highlights potential roles for cytoplasmic components of the oocyte in supporting nuclear reprogramming. The transcriptional regulators identified may contribute to the overall process as downstream effectors.
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Chang KJ, Rasband MN. Excitable domains of myelinated nerves: axon initial segments and nodes of Ranvier. CURRENT TOPICS IN MEMBRANES 2013; 72:159-92. [PMID: 24210430 DOI: 10.1016/b978-0-12-417027-8.00005-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Neurons are highly polarized cells. They can be subdivided into at least two structurally and functionally distinct domains: somatodendritic and axonal domains. The somatodendritic domain receives and integrates upstream input signals, and the axonal domain generates and relays outputs in the form of action potentials to the downstream target. Demand for quick response to the harsh surroundings prompted evolution to equip vertebrates' neurons with a remarkable glia-derived structure called myelin. Not only Insulating the axon, myelinating glia also rearrange the axonal components and elaborate functional subdomains along the axon. Proper functioning of all theses domains and subdomains is vital for a normal, efficient nervous system.
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Affiliation(s)
- Kae-Jiun Chang
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, USA
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Einheber S, Meng X, Rubin M, Lam I, Mohandas N, An X, Shrager P, Kissil J, Maurel P, Salzer JL. The 4.1B cytoskeletal protein regulates the domain organization and sheath thickness of myelinated axons. Glia 2012; 61:240-53. [PMID: 23109359 DOI: 10.1002/glia.22430] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 09/10/2012] [Indexed: 12/13/2022]
Abstract
Myelinated axons are organized into specialized domains critical to their function in saltatory conduction, i.e., nodes, paranodes, juxtaparanodes, and internodes. Here, we describe the distribution and role of the 4.1B protein in this organization. 4.1B is expressed by neurons, and at lower levels by Schwann cells, which also robustly express 4.1G. Immunofluorescence and immuno-EM demonstrates 4.1B is expressed subjacent to the axon membrane in all domains except the nodes. Mice deficient in 4.1B have preserved paranodes, based on marker staining and EM in contrast to the juxtaparanodes, which are substantially affected in both the PNS and CNS. The juxtaparanodal defect is evident in developing and adult nerves and is neuron-autonomous based on myelinating cocultures in which wt Schwann cells were grown with 4.1B-deficient neurons. Despite the juxtaparanodal defect, nerve conduction velocity is unaffected. Preservation of paranodal markers in 4.1B deficient mice is associated with, but not dependent on an increase of 4.1R at the axonal paranodes. Loss of 4.1B in the axon is also associated with reduced levels of the internodal proteins, Necl-1 and Necl-2, and of alpha-2 spectrin. Mutant nerves are modestly hypermyelinated and have increased numbers of Schmidt-Lanterman incisures, increased expression of 4.1G, and express a residual, truncated isoform of 4.1B. These results demonstrate that 4.1B is a key cytoskeletal scaffold for axonal adhesion molecules expressed in the juxtaparanodal and internodal domains that unexpectedly regulates myelin sheath thickness.
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Affiliation(s)
- Steven Einheber
- School of Health Sciences, Hunter College, City University of New York, New York, New York, USA
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Ivanovic A, Horresh I, Golan N, Spiegel I, Sabanay H, Frechter S, Ohno S, Terada N, Möbius W, Rosenbluth J, Brose N, Peles E. The cytoskeletal adapter protein 4.1G organizes the internodes in peripheral myelinated nerves. ACTA ACUST UNITED AC 2012; 196:337-44. [PMID: 22291039 PMCID: PMC3275379 DOI: 10.1083/jcb.201111127] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Deletion of the Schwann cell cytoskeletal adapter protein 4.1G led to aberrant distribution of glial adhesion molecules and axonal proteins along the internodes. Myelinating Schwann cells regulate the localization of ion channels on the surface of the axons they ensheath. This function depends on adhesion complexes that are positioned at specific membrane domains along the myelin unit. Here we show that the precise localization of internodal proteins depends on the expression of the cytoskeletal adapter protein 4.1G in Schwann cells. Deletion of 4.1G in mice resulted in aberrant distribution of both glial adhesion molecules and axonal proteins that were present along the internodes. In wild-type nerves, juxtaparanodal proteins (i.e., Kv1 channels, Caspr2, and TAG-1) were concentrated throughout the internodes in a double strand that flanked paranodal junction components (i.e., Caspr, contactin, and NF155), and apposes the inner mesaxon of the myelin sheath. In contrast, in 4.1G−/− mice, these proteins “piled up” at the juxtaparanodal region or aggregated along the internodes. These findings suggest that protein 4.1G contributes to the organization of the internodal axolemma by targeting and/or maintaining glial transmembrane proteins along the axoglial interface.
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Affiliation(s)
- Aleksandra Ivanovic
- Department of Molecular Neurobiology and 2 Department of Neurogenetics, Max Planck Institute of Experimental Medicine, D-37075 Göttingen, Germany
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Duflocq A, Chareyre F, Giovannini M, Couraud F, Davenne M. Characterization of the axon initial segment (AIS) of motor neurons and identification of a para-AIS and a juxtapara-AIS, organized by protein 4.1B. BMC Biol 2011; 9:66. [PMID: 21958379 PMCID: PMC3198992 DOI: 10.1186/1741-7007-9-66] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/29/2011] [Indexed: 11/26/2022] Open
Abstract
Background The axon initial segment (AIS) plays a crucial role: it is the site where neurons initiate their electrical outputs. Its composition in terms of voltage-gated sodium (Nav) and voltage-gated potassium (Kv) channels, as well as its length and localization determine the neuron's spiking properties. Some neurons are able to modulate their AIS length or distance from the soma in order to adapt their excitability properties to their activity level. It is therefore crucial to characterize all these parameters and determine where the myelin sheath begins in order to assess a neuron's excitability properties and ability to display such plasticity mechanisms. If the myelin sheath starts immediately after the AIS, another question then arises as to how would the axon be organized at its first myelin attachment site; since AISs are different from nodes of Ranvier, would this particular axonal region resemble a hemi-node of Ranvier? Results We have characterized the AIS of mouse somatic motor neurons. In addition to constant determinants of excitability properties, we found heterogeneities, in terms of AIS localization and Nav composition. We also identified in all α motor neurons a hemi-node-type organization, with a contactin-associated protein (Caspr)+ paranode-type, as well as a Caspr2+ and Kv1+ juxtaparanode-type compartment, referred to as a para-AIS and a juxtapara (JXP)-AIS, adjacent to the AIS, where the myelin sheath begins. We found that Kv1 channels appear in the AIS, para-AIS and JXP-AIS concomitantly with myelination and are progressively excluded from the para-AIS. Their expression in the AIS and JXP-AIS is independent from transient axonal glycoprotein-1 (TAG-1)/Caspr2, in contrast to juxtaparanodes, and independent from PSD-93. Data from mice lacking the cytoskeletal linker protein 4.1B show that this protein is necessary to form the Caspr+ para-AIS barrier, ensuring the compartmentalization of Kv1 channels and the segregation of the AIS, para-AIS and JXP-AIS. Conclusions α Motor neurons have heterogeneous AISs, which underlie different spiking properties. However, they all have a para-AIS and a JXP-AIS contiguous to their AIS, where the myelin sheath begins, which might limit some AIS plasticity. Protein 4.1B plays a key role in ensuring the proper molecular compartmentalization of this hemi-node-type region.
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