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Pozzi E, Terribile G, Cherchi L, Di Girolamo S, Sancini G, Alberti P. Ion Channel and Transporter Involvement in Chemotherapy-Induced Peripheral Neurotoxicity. Int J Mol Sci 2024; 25:6552. [PMID: 38928257 PMCID: PMC11203899 DOI: 10.3390/ijms25126552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Revised: 06/06/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
The peripheral nervous system can encounter alterations due to exposure to some of the most commonly used anticancer drugs (platinum drugs, taxanes, vinca alkaloids, proteasome inhibitors, thalidomide), the so-called chemotherapy-induced peripheral neurotoxicity (CIPN). CIPN can be long-lasting or even permanent, and it is detrimental for the quality of life of cancer survivors, being associated with persistent disturbances such as sensory loss and neuropathic pain at limb extremities due to a mostly sensory axonal polyneuropathy/neuronopathy. In the state of the art, there is no efficacious preventive/curative treatment for this condition. Among the reasons for this unmet clinical and scientific need, there is an uncomplete knowledge of the pathogenetic mechanisms. Ion channels and transporters are pivotal elements in both the central and peripheral nervous system, and there is a growing body of literature suggesting that they might play a role in CIPN development. In this review, we first describe the biophysical properties of these targets and then report existing data for the involvement of ion channels and transporters in CIPN, thus paving the way for new approaches/druggable targets to cure and/or prevent CIPN.
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Affiliation(s)
- Eleonora Pozzi
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.P.); (L.C.); (S.D.G.)
| | - Giulia Terribile
- Human Physiology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (G.T.); (G.S.)
| | - Laura Cherchi
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.P.); (L.C.); (S.D.G.)
| | - Sara Di Girolamo
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.P.); (L.C.); (S.D.G.)
| | - Giulio Sancini
- Human Physiology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (G.T.); (G.S.)
| | - Paola Alberti
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.P.); (L.C.); (S.D.G.)
- Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
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2
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Dai Y, Cheng Y, Ge R, Chen K, Yang L. Exercise-induced adaptation of neurons in the vertebrate locomotor system. JOURNAL OF SPORT AND HEALTH SCIENCE 2024; 13:160-171. [PMID: 37914153 PMCID: PMC10980905 DOI: 10.1016/j.jshs.2023.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 09/20/2023] [Accepted: 10/07/2023] [Indexed: 11/03/2023]
Abstract
Vertebrate neurons are highly dynamic cells that undergo several alterations in their functioning and physiologies in adaptation to various external stimuli. In particular, how these neurons respond to physical exercise has long been an area of active research. Studies of the vertebrate locomotor system's adaptability suggest multiple mechanisms are involved in the regulation of neuronal activity and properties during exercise. In this brief review, we highlight recent results and insights from the field with a focus on the following mechanisms: (a) alterations in neuronal excitability during acute exercise; (b) alterations in neuronal excitability after chronic exercise; (c) exercise-induced changes in neuronal membrane properties via modulation of ion channel activity; (d) exercise-enhanced dendritic plasticity; and (e) exercise-induced alterations in neuronal gene expression and protein synthesis. Our hope is to update the community with a cellular and molecular understanding of the recent mechanisms underlying the adaptability of the vertebrate locomotor system in response to both acute and chronic physical exercise.
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Affiliation(s)
- Yue Dai
- Key Lab of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, College of Physical Education and Health Care, East China Normal University, Shanghai 200241, China; Shanghai Key Laboratory of Multidimensional Information Processing, School of Communication and Electronic Engineering, East China Normal University, Shanghai 200241, China.
| | - Yi Cheng
- Key Lab of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, College of Physical Education and Health Care, East China Normal University, Shanghai 200241, China
| | - Renkai Ge
- School of Physical Education and Health Care, East China Jiaotong University, Nanchang 330013, China
| | - Ke Chen
- Key Laboratory of High Confidence Software Technologies of Ministry of Education, School of Computer Science, Peking University, Beijing 100871, China
| | - Liming Yang
- Key Lab of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, College of Physical Education and Health Care, East China Normal University, Shanghai 200241, China
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3
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Dupuy M, Gueguinou M, Potier-Cartereau M, Lézot F, Papin M, Chantôme A, Rédini F, Vandier C, Verrecchia F. SK Ca- and Kv1-type potassium channels and cancer: Promising therapeutic targets? Biochem Pharmacol 2023; 216:115774. [PMID: 37678626 DOI: 10.1016/j.bcp.2023.115774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/29/2023] [Accepted: 08/30/2023] [Indexed: 09/09/2023]
Abstract
Ion channels are transmembrane structures that allow the passage of ions across cell membranes such as the plasma membrane or the membranes of various organelles like the nucleus, endoplasmic reticulum, Golgi apparatus or mitochondria. Aberrant expression of various ion channels has been demonstrated in several tumor cells, leading to the promotion of key functions in tumor development, such as cell proliferation, resistance to apoptosis, angiogenesis, invasion and metastasis. The link between ion channels and these key biological functions that promote tumor development has led to the classification of cancers as oncochannelopathies. Among all ion channels, the most varied and numerous, forming the largest family, are the potassium channels, with over 70 genes encoding them in humans. In this context, this review will provide a non-exhaustive overview of the role of plasma membrane potassium channels in cancer, describing 1) the nomenclature and structure of potassium channels, 2) the role of these channels in the control of biological functions that promotes tumor development such as proliferation, migration and cell death, and 3) the role of two particular classes of potassium channels, the SKCa- and Kv1- type potassium channels in cancer progression.
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Affiliation(s)
- Maryne Dupuy
- Nantes Université, Inserm UMR 1307, CNRS UMR 6075, Université d'Angers, CRCI2NA, F-44000 Nantes, France.
| | | | | | - Frédéric Lézot
- Sorbonne University, INSERM UMR933, Hôpital Trousseau (AP-HP), Paris F-75012, France
| | - Marion Papin
- N2C UMR 1069, University of Tours, INSERM, Tours, France
| | | | - Françoise Rédini
- Nantes Université, Inserm UMR 1307, CNRS UMR 6075, Université d'Angers, CRCI2NA, F-44000 Nantes, France
| | | | - Franck Verrecchia
- Nantes Université, Inserm UMR 1307, CNRS UMR 6075, Université d'Angers, CRCI2NA, F-44000 Nantes, France.
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4
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Escobar AP, Meza R, Gonzalez M, Henny P, Andrés ME. Immunolocalization of kappa opioid receptors in the axon initial segment of a group of embryonic mesencephalic dopamine neurons. IBRO Neurosci Rep 2022; 12:411-418. [PMID: 35746971 PMCID: PMC9210487 DOI: 10.1016/j.ibneur.2022.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 05/04/2022] [Accepted: 05/08/2022] [Indexed: 11/13/2022] Open
Abstract
The dopamine mesolimbic system is a major circuit involved in controlling goal-directed behaviors. Dopamine D2 receptors (D2R) and kappa opioid receptors (KOR) are abundant Gi protein-coupled receptors in the mesolimbic system. D2R and KOR share several functions in dopamine mesencephalic neurons, such as regulation of dopamine release and uptake, and firing of dopamine neurons. In addition, KOR and D2R modulate each other functioning. This evidence indicates that both receptors functionally interact, however, their colocalization in the mesostriatal system has not been addressed. Immunofluorescent assays were performed in cultured dopamine neurons and adult mice’s brain tissue to answer this question. We observed that KOR and D2R are present in similar density in dendrites and soma of cultured dopamine neurons, but in a segregated manner. Interestingly, KOR immunolabelling was observed in the first part of the axon, colocalizing with Ankyrin in 20% of cultured dopamine neurons, indicative that KOR is present in the axon initial segment (AIS) of a group of dopaminergic neurons. In the adult brain, KOR and D2R are also segregated in striatal tissue. While the KOR label is in fiber tracts such as the striatal streaks, corpus callosum, and anterior commissure, D2R is located mainly within the striatum and nucleus accumbens, surrounding fiber tracts. D2R is also localized in some fibers that are mostly different from those positives for KOR. In conclusion, KOR and D2R are present in the soma and dendrites of mesencephalic dopaminergic neurons, but KOR is also found in the AIS of a subpopulation of these neurons. KOR and D2R localize in cell bodies of primary cultured TH neurons. In primary cultured TH neurons KOR localizes in axon initial segment. KOR and D2R co-localize in cell bodies of the CPu and NAc.
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LGI1-ADAM22-MAGUK configures transsynaptic nanoalignment for synaptic transmission and epilepsy prevention. Proc Natl Acad Sci U S A 2021; 118:2022580118. [PMID: 33397806 PMCID: PMC7826393 DOI: 10.1073/pnas.2022580118] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
This study addresses a fundamental question in neuroscience, namely how does the presynaptic component of the synapse precisely align with the postsynaptic component? This is essential for the proper transmission of signals across the synapse. This paper focuses on a set of transsynaptic, epilepsy-related proteins that are essential for this alignment. We show that the LGI1–ADAM22–MAGUK complex is a key player in the nanoarchitecture of the synapse, such that the release site is directly apposed to the nanocluster of glutamate receptors. Physiological functioning and homeostasis of the brain rely on finely tuned synaptic transmission, which involves nanoscale alignment between presynaptic neurotransmitter-release machinery and postsynaptic receptors. However, the molecular identity and physiological significance of transsynaptic nanoalignment remain incompletely understood. Here, we report that epilepsy gene products, a secreted protein LGI1 and its receptor ADAM22, govern transsynaptic nanoalignment to prevent epilepsy. We found that LGI1–ADAM22 instructs PSD-95 family membrane-associated guanylate kinases (MAGUKs) to organize transsynaptic protein networks, including NMDA/AMPA receptors, Kv1 channels, and LRRTM4–Neurexin adhesion molecules. Adam22ΔC5/ΔC5 knock-in mice devoid of the ADAM22–MAGUK interaction display lethal epilepsy of hippocampal origin, representing the mouse model for ADAM22-related epileptic encephalopathy. This model shows less-condensed PSD-95 nanodomains, disordered transsynaptic nanoalignment, and decreased excitatory synaptic transmission in the hippocampus. Strikingly, without ADAM22 binding, PSD-95 cannot potentiate AMPA receptor-mediated synaptic transmission. Furthermore, forced coexpression of ADAM22 and PSD-95 reconstitutes nano-condensates in nonneuronal cells. Collectively, this study reveals LGI1–ADAM22–MAGUK as an essential component of transsynaptic nanoarchitecture for precise synaptic transmission and epilepsy prevention.
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6
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Pelot NA, Catherall DC, Thio BJ, Titus ND, Liang ED, Henriquez CS, Grill WM. Excitation properties of computational models of unmyelinated peripheral axons. J Neurophysiol 2021; 125:86-104. [PMID: 33085556 PMCID: PMC8087387 DOI: 10.1152/jn.00315.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 09/09/2020] [Accepted: 09/14/2020] [Indexed: 12/19/2022] Open
Abstract
Biophysically based computational models of nerve fibers are important tools for designing electrical stimulation therapies, investigating drugs that affect ion channels, and studying diseases that affect neurons. Although peripheral nerves are primarily composed of unmyelinated axons (i.e., C-fibers), most modeling efforts focused on myelinated axons. We implemented the single-compartment model of vagal afferents from Schild et al. (1994) (Schild JH, Clark JW, Hay M, Mendelowitz D, Andresen MC, Kunze DL. J Neurophysiol 71: 2338-2358, 1994) and extended the model into a multicompartment axon, presenting the first cable model of a C-fiber vagal afferent. We also implemented the updated parameters from the Schild and Kunze (1997) model (Schild JH, Kunze DL. J Neurophysiol 78: 3198-3209, 1997). We compared the responses of these novel models with those of three published models of unmyelinated axons (Rattay F, Aberham M. IEEE Trans Biomed Eng 40: 1201-1209, 1993; Sundt D, Gamper N, Jaffe DB. J Neurophysiol 114: 3140-3153, 2015; Tigerholm J, Petersson ME, Obreja O, Lampert A, Carr R, Schmelz M, Fransén E. J Neurophysiol 111: 1721-1735, 2014) and with experimental data from single-fiber recordings. Comparing the two models by Schild et al. (1994, 1997) revealed that differences in rest potential and action potential shape were driven by changes in maximum conductances rather than changes in sodium channel dynamics. Comparing the five model axons, the conduction speeds and strength-duration responses were largely within expected ranges, but none of the models captured the experimental threshold recovery cycle-including a complete absence of late subnormality in the models-and their action potential shapes varied dramatically. The Tigerholm et al. (2014) model best reproduced the experimental data, but these modeling efforts make clear that additional data are needed to parameterize and validate future models of autonomic C-fibers.NEW & NOTEWORTHY Peripheral nerves are primarily composed of unmyelinated axons, and there is growing interest in electrical stimulation of the autonomic nervous system to treat various diseases. We present the first cable model of an unmyelinated vagal nerve fiber and compare its ion channel isoforms and conduction responses with other published models of unmyelinated axons, establishing important tools for advancing modeling of autonomic nerves.
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Affiliation(s)
- Nicole A Pelot
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - David C Catherall
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Brandon J Thio
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Nathan D Titus
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Edward D Liang
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Craig S Henriquez
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
- Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina
- Department of Neurobiology, Duke University, Durham, North Carolina
- Department of Neurosurgery, Duke University, Durham, North Carolina
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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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Masoli S, Ottaviani A, Casali S, D’Angelo E. Cerebellar Golgi cell models predict dendritic processing and mechanisms of synaptic plasticity. PLoS Comput Biol 2020; 16:e1007937. [PMID: 33378395 PMCID: PMC7837495 DOI: 10.1371/journal.pcbi.1007937] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 01/26/2021] [Accepted: 11/13/2020] [Indexed: 02/06/2023] Open
Abstract
The Golgi cells are the main inhibitory interneurons of the cerebellar granular layer. Although recent works have highlighted the complexity of their dendritic organization and synaptic inputs, the mechanisms through which these neurons integrate complex input patterns remained unknown. Here we have used 8 detailed morphological reconstructions to develop multicompartmental models of Golgi cells, in which Na, Ca, and K channels were distributed along dendrites, soma, axonal initial segment and axon. The models faithfully reproduced a rich pattern of electrophysiological and pharmacological properties and predicted the operating mechanisms of these neurons. Basal dendrites turned out to be more tightly electrically coupled to the axon initial segment than apical dendrites. During synaptic transmission, parallel fibers caused slow Ca-dependent depolarizations in apical dendrites that boosted the axon initial segment encoder and Na-spike backpropagation into basal dendrites, while inhibitory synapses effectively shunted backpropagating currents. This oriented dendritic processing set up a coincidence detector controlling voltage-dependent NMDA receptor unblock in basal dendrites, which, by regulating local calcium influx, may provide the basis for spike-timing dependent plasticity anticipated by theory.
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Affiliation(s)
- Stefano Masoli
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | | | - Stefano Casali
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Egidio D’Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
- Brain Connectivity Center, IRCCS Mondino Foundation, Pavia, Italy
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9
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Lubetzki C, Sol-Foulon N, Desmazières A. Nodes of Ranvier during development and repair in the CNS. Nat Rev Neurol 2020; 16:426-439. [DOI: 10.1038/s41582-020-0375-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2020] [Indexed: 01/01/2023]
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10
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Nirenberg VA, Yifrach O. Bridging the Molecular-Cellular Gap in Understanding Ion Channel Clustering. Front Pharmacol 2020; 10:1644. [PMID: 32082156 PMCID: PMC7000920 DOI: 10.3389/fphar.2019.01644] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/16/2019] [Indexed: 01/07/2023] Open
Abstract
The clustering of many voltage-dependent ion channel molecules at unique neuronal membrane sites such as axon initial segments, nodes of Ranvier, or the post-synaptic density, is an active process mediated by the interaction of ion channels with scaffold proteins and is of immense importance for electrical signaling. Growing evidence indicates that the density of ion channels at such membrane sites may affect action potential conduction properties and synaptic transmission. However, despite the emerging importance of ion channel density for electrical signaling, how ion channel-scaffold protein molecular interactions lead to cellular ion channel clustering, and how this process is regulated are largely unknown. In this review, we emphasize that voltage-dependent ion channel density at native clustering sites not only affects the density of ionic current fluxes but may also affect the conduction properties of the channel and/or the physical properties of the membrane at such locations, all changes that are expected to affect action potential conduction properties. Using the concrete example of the prototypical Shaker voltage-activated potassium channel (Kv) protein, we demonstrate how insight into the regulation of cellular ion channel clustering can be obtained when the molecular mechanism of ion channel-scaffold protein interaction is known. Our review emphasizes that such mechanistic knowledge is essential, and when combined with super-resolution imaging microscopy, can serve to bridge the molecular-cellular gap in understanding the regulation of ion channel clustering. Pressing questions, challenges and future directions in addressing ion channel clustering and its regulation are discussed.
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Affiliation(s)
| | - Ofer Yifrach
- Department of Life Sciences and the Zlotowski Center for Neurosciences, Ben-Gurion University of the Negev, Be’er Sheva, Israel
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11
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Guo D, Hu H, Pan S. Oligodendrocyte dysfunction and regeneration failure: A novel hypothesis of delayed encephalopathy after carbon monoxide poisoning. Med Hypotheses 2019; 136:109522. [PMID: 31841765 DOI: 10.1016/j.mehy.2019.109522] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 12/03/2019] [Accepted: 12/07/2019] [Indexed: 12/20/2022]
Abstract
Carbon monoxide (CO) poisoning usually causes brain lesions and delayed encephalopathy, also known as delayed neurological sequelae (DNS). Demyelination of white matter (WM) is one of the most common sites of abnormalities in patients with DNS, but its mechanisms remain unclear. Oligodendrocytes (OLs) are myelinated cells that ensure the rapid conduction of neuronal axon signals and provide the nutritional factors necessary for maintaining nerve integrity in the central nervous system (CNS). OLs readily regenerate and replace damaged myelin membranes around axons in the adult mammalian CNS following demyelination. The ability to regenerate OLs depends on the availability of precursor cells (OPCs) in the CNS of adults. Multiple injury-related signals can induce OPC expansion followed by OL differentiation, axonal contact and myelin regeneration (remyelination). Therefore, OL dysfunction and regeneration failure in the deep WM of the brain are the key pathophysiological mechanisms leading to delayed brain injury after CO poisoning. CO-induced toxicity may interfere with OL function and render OPCs unable to regenerate OLs through some unclear mechanisms, leading to progressive demyelinating damage and resulting in DNS. In the future, combination therapies to reduce OL damage and promote OPC differentiation and remyelination may be important for the prevention and treatmentof DNS after CO poisoning.
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Affiliation(s)
- Dazhi Guo
- Department of Hyperbaric Oxygen, The Sixth Medical Center, PLA General Hospital, Beijing 100048, China.
| | - Huijun Hu
- Department of Hyperbaric Oxygen, The Sixth Medical Center, PLA General Hospital, Beijing 100048, China
| | - Shuyi Pan
- Department of Hyperbaric Oxygen, The Sixth Medical Center, PLA General Hospital, Beijing 100048, China
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12
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Ranjan R, Logette E, Marani M, Herzog M, Tâche V, Scantamburlo E, Buchillier V, Markram H. A Kinetic Map of the Homomeric Voltage-Gated Potassium Channel (Kv) Family. Front Cell Neurosci 2019; 13:358. [PMID: 31481875 PMCID: PMC6710402 DOI: 10.3389/fncel.2019.00358] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 07/19/2019] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated potassium (Kv) channels, encoded by 40 genes, repolarize all electrically excitable cells, including plant, cardiac, and neuronal cells. Although these genes were fully sequenced decades ago, a comprehensive kinetic characterization of all Kv channels is still missing, especially near physiological temperature. Here, we present a standardized kinetic map of the 40 homomeric Kv channels systematically characterized at 15, 25, and 35°C. Importantly, the Kv kinetics at 35°C differ significantly from commonly reported kinetics, usually performed at room temperature. We observed voltage-dependent Q10 for all active Kv channels and inherent heterogeneity in kinetics for some of them. Kinetic properties are consistent across different host cell lines and conserved across mouse, rat, and human. All electrophysiology data from all Kv channels are made available through a public website (Channelpedia). This dataset provides a solid foundation for exploring kinetics of heteromeric channels, roles of auxiliary subunits, kinetic modulation, and for building accurate Kv models.
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Affiliation(s)
- Rajnish Ranjan
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Emmanuelle Logette
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland.,Laboratory of Neural Microcircuitry, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Michela Marani
- Laboratory of Neural Microcircuitry, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Mirjia Herzog
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland.,Laboratory of Neural Microcircuitry, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Valérie Tâche
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Enrico Scantamburlo
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Valérie Buchillier
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Henry Markram
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland.,Laboratory of Neural Microcircuitry, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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13
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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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Yermakov LM, Hong LA, Drouet DE, Griggs RB, Susuki K. Functional Domains in Myelinated Axons. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:65-83. [PMID: 31760639 DOI: 10.1007/978-981-32-9636-7_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Propagation of action potentials along axons is optimized through interactions between neurons and myelinating glial cells. Myelination drives division of the axons into distinct molecular domains including nodes of Ranvier. The high density of voltage-gated sodium channels at nodes generates action potentials allowing for rapid and efficient saltatory nerve conduction. At paranodes flanking both sides of the nodes, myelinating glial cells interact with axons, forming junctions that are essential for node formation and maintenance. Recent studies indicate that the disruption of these specialized axonal domains is involved in the pathophysiology of various neurological diseases. Loss of paranodal axoglial junctions due to genetic mutations or autoimmune attack against the paranodal proteins leads to nerve conduction failure and neurological symptoms. Breakdown of nodal and paranodal proteins by calpains, the calcium-dependent cysteine proteases, may be a common mechanism involved in various nervous system diseases and injuries. This chapter reviews recent progress in neurobiology and pathophysiology of specialized axonal domains along myelinated nerve fibers.
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Affiliation(s)
- Leonid M Yermakov
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
| | - Lulu A Hong
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
| | - Domenica E Drouet
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
| | - Ryan B Griggs
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
| | - Keiichiro Susuki
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA.
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The Axon Initial Segment: An Updated Viewpoint. J Neurosci 2018; 38:2135-2145. [PMID: 29378864 DOI: 10.1523/jneurosci.1922-17.2018] [Citation(s) in RCA: 164] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 01/20/2018] [Accepted: 01/25/2018] [Indexed: 12/20/2022] Open
Abstract
At the base of axons sits a unique compartment called the axon initial segment (AIS). The AIS generates and shapes the action potential before it is propagated along the axon. Neuronal excitability thus depends crucially on the AIS composition and position, and these adapt to developmental and physiological conditions. The AIS also demarcates the boundary between the somatodendritic and axonal compartments. Recent studies have brought insights into the molecular architecture of the AIS and how it regulates protein trafficking. This Viewpoints article summarizes current knowledge about the AIS and highlights future challenges in understanding this key actor of neuronal physiology.
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Cadet JL, Brannock C, Krasnova IN, Jayanthi S, Ladenheim B, McCoy MT, Walther D, Godino A, Pirooznia M, Lee RS. Genome-wide DNA hydroxymethylation identifies potassium channels in the nucleus accumbens as discriminators of methamphetamine addiction and abstinence. Mol Psychiatry 2017; 22:1196-1204. [PMID: 27046646 PMCID: PMC7405865 DOI: 10.1038/mp.2016.48] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 01/28/2016] [Accepted: 02/18/2016] [Indexed: 12/17/2022]
Abstract
Epigenetic consequences of exposure to psychostimulants are substantial but the relationship of these changes to compulsive drug taking and abstinence is not clear. Here, we used a paradigm that helped to segregate rats that reduce or stop their methamphetamine (METH) intake (nonaddicted) from those that continue to take the drug compulsively (addicted) in the presence of footshocks. We used that model to investigate potential alterations in global DNA hydroxymethylation in the nucleus accumbens (NAc) because neuroplastic changes in the NAc may participate in the development and maintenance of drug-taking behaviors. We found that METH-addicted rats did indeed show differential DNA hydroxymethylation in comparison with both control and nonaddicted rats. Nonaddicted rats also showed differences from control rats. Differential DNA hydroxymethylation observed in addicted rats occurred mostly at intergenic sites located on long and short interspersed elements. Interestingly, differentially hydroxymethylated regions in genes encoding voltage (Kv1.1, Kv1.2, Kvb1 and Kv2.2)- and calcium (Kcnma1, Kcnn1 and Kcnn2)-gated potassium channels observed in the NAc of nonaddicted rats were accompanied by increased mRNA levels of these potassium channels when compared with mRNA expression in METH-addicted rats. These observations indicate that changes in differentially hydroxymethylated regions and increased expression of specific potassium channels in the NAc may promote abstinence from drug-taking behaviors. Thus, activation of specific subclasses of voltage- and/or calcium-gated potassium channels may provide an important approach to the beneficial treatment for METH addiction.
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Affiliation(s)
- Jean Lud Cadet
- Molecular Neuropsychiatry Research Branch, NIDA Intramural Research Program Baltimore, MD, USA
| | - Christie Brannock
- Molecular Neuropsychiatry Research Branch, NIDA Intramural Research Program Baltimore, MD, USA
| | - Irina N. Krasnova
- Molecular Neuropsychiatry Research Branch, NIDA Intramural Research Program Baltimore, MD, USA
| | - Subramaniam Jayanthi
- Molecular Neuropsychiatry Research Branch, NIDA Intramural Research Program Baltimore, MD, USA
| | - Bruce Ladenheim
- Molecular Neuropsychiatry Research Branch, NIDA Intramural Research Program Baltimore, MD, USA
| | - Michael T. McCoy
- Molecular Neuropsychiatry Research Branch, NIDA Intramural Research Program Baltimore, MD, USA
| | - Donna Walther
- Molecular Neuropsychiatry Research Branch, NIDA Intramural Research Program Baltimore, MD, USA
| | - Arthur Godino
- Département de Biologie, École Normale Supérieure de Lyon, Lyon, France
| | - Mehdi Pirooznia
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Richard S. Lee
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA
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Chamberlain KA, Nanescu SE, Psachoulia K, Huang JK. Oligodendrocyte regeneration: Its significance in myelin replacement and neuroprotection in multiple sclerosis. Neuropharmacology 2016; 110:633-643. [PMID: 26474658 PMCID: PMC4841742 DOI: 10.1016/j.neuropharm.2015.10.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 09/22/2015] [Accepted: 10/05/2015] [Indexed: 12/12/2022]
Abstract
Oligodendrocytes readily regenerate and replace myelin membranes around axons in the adult mammalian central nervous system (CNS) following injury. The ability to regenerate oligodendrocytes depends on the availability of neural progenitors called oligodendrocyte precursor cells (OPCs) in the adult CNS that respond to injury-associated signals to induce OPC expansion followed by oligodendrocyte differentiation, axonal contact and myelin regeneration (remyelination). Remyelination ensures the maintenance of axonal conduction, and the oligodendrocytes themselves provide metabolic factors that are necessary to maintain neuronal integrity. Recent advances in oligodendrocyte regeneration research are beginning to shed light on critical intrinsic signals, as well as extrinsic, environmental factors that regulate the distinct steps of oligodendrocyte lineage progression and myelin replacement under CNS injury. These studies may offer novel pharmacological targets for regenerative medicine in inflammatory demyelinating disorders in the CNS such as multiple sclerosis. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.
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Affiliation(s)
- Kelly A Chamberlain
- Department of Biology, Georgetown University, Washington, D.C., USA; Interdisciplinary Program in Neuroscience, Georgetown University, Washington, D.C., USA
| | - Sonia E Nanescu
- Department of Biology, Georgetown University, Washington, D.C., USA
| | | | - Jeffrey K Huang
- Department of Biology, Georgetown University, Washington, D.C., USA; Interdisciplinary Program in Neuroscience, Georgetown University, Washington, D.C., USA.
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Abstract
UNLABELLED The role of interneurons in cortical microcircuits is strongly influenced by their passive and active electrical properties. Although different types of interneurons exhibit unique electrophysiological properties recorded at the soma, it is not yet clear whether these differences are also manifested in other neuronal compartments. To address this question, we have used voltage-sensitive dye to image the propagation of action potentials into the fine collaterals of axons and dendrites in two of the largest cortical interneuron subtypes in the mouse: fast-spiking interneurons, which are typically basket or chandelier neurons; and somatostatin containing interneurons, which are typically regular spiking Martinotti cells. We found that fast-spiking and somatostatin-expressing interneurons differed in their electrophysiological characteristics along their entire dendrosomatoaxonal extent. The action potentials generated in the somata and axons, including axon collaterals, of somatostatin-expressing interneurons are significantly broader than those generated in the same compartments of fast-spiking inhibitory interneurons. In addition, action potentials back-propagated into the dendrites of somatostatin-expressing interneurons much more readily than fast-spiking interneurons. Pharmacological investigations suggested that axonal action potential repolarization in both cell types depends critically upon Kv1 channels, whereas the axonal and somatic action potentials of somatostatin-expressing interneurons also depend on BK Ca(2+)-activated K(+) channels. These results indicate that the two broad classes of interneurons studied here have expressly different subcellular physiological properties, allowing them to perform unique computational roles in cortical circuit operations. SIGNIFICANCE STATEMENT Neurons in the cerebral cortex are of two major types: excitatory and inhibitory. The proper balance of excitation and inhibition in the brain is critical for its operation. Neurons contain three main compartments: dendritic, somatic, and axonal. How the neurons receive information, process it, and pass on new information depends upon how these three compartments operate. While it has long been assumed that axons are simply for conducting information from the cell body to the synapses, here we demonstrate that the axons of different types of interneurons, the inhibitory cells, possess differing electrophysiological properties. This result implies that differing types of interneurons perform different tasks in the cortex, not only through their anatomical connections, but also through how their axons operate.
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Gründemann J, Clark BA. Calcium-Activated Potassium Channels at Nodes of Ranvier Secure Axonal Spike Propagation. Cell Rep 2015; 12:1715-22. [PMID: 26344775 PMCID: PMC4590545 DOI: 10.1016/j.celrep.2015.08.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 06/22/2015] [Accepted: 08/05/2015] [Indexed: 12/01/2022] Open
Abstract
Functional connectivity between brain regions relies on long-range signaling by myelinated axons. This is secured by saltatory action potential propagation that depends fundamentally on sodium channel availability at nodes of Ranvier. Although various potassium channel types have been anatomically localized to myelinated axons in the brain, direct evidence for their functional recruitment in maintaining node excitability is scarce. Cerebellar Purkinje cells provide continuous input to their targets in the cerebellar nuclei, reliably transmitting axonal spikes over a wide range of rates, requiring a constantly available pool of nodal sodium channels. We show that the recruitment of calcium-activated potassium channels (IK, KCa3.1) by local, activity-dependent calcium (Ca2+) influx at nodes of Ranvier via a T-type voltage-gated Ca2+ current provides a powerful mechanism that likely opposes depolarizing block at the nodes and is thus pivotal to securing continuous axonal spike propagation in spontaneously firing Purkinje cells. Activity-dependent node of Ranvier Ca2+ influx in Purkinje cell axons Cav and KCa3.1 channels required for axonal spike propagation Nodal KCa3.1 channels provide repolarizing drive to sustain axonal spike propagation
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Affiliation(s)
- Jan Gründemann
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Beverley A Clark
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK.
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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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Abstract
In excitable cells, ion channels are frequently challenged by repetitive stimuli, and their responses shape cellular behavior by regulating the duration and termination of bursts of action potentials. We have investigated the behavior of Shaker family voltage-gated potassium (Kv) channels subjected to repetitive stimuli, with a particular focus on Kv1.2. Genetic deletion of this subunit results in complete mortality within 2 weeks of birth in mice, highlighting a critical physiological role for Kv1.2. Kv1.2 channels exhibit a unique property described previously as "prepulse potentiation," in which activation by a depolarizing step facilitates activation in a subsequent pulse. In this study, we demonstrate that this property enables Kv1.2 channels to exhibit use-dependent activation during trains of very brief depolarizations. Also, Kv subunits usually assemble into heteromeric channels in the central nervous system, generating diversity of function and sensitivity to signaling mechanisms. We demonstrate that other Kv1 channel types do not exhibit use-dependent activation, but this property is conferred in heteromeric channel complexes containing even a single Kv1.2 subunit. This regulatory mechanism is observed in mammalian cell lines as well as primary cultures of hippocampal neurons. Our findings illustrate that use-dependent activation is a unique property of Kv1.2 that persists in heteromeric channel complexes and may influence function of hippocampal neurons.
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NMDA receptors and L-type voltage-gated Ca²⁺ channels mediate the expression of bidirectional homeostatic intrinsic plasticity in cultured hippocampal neurons. Neuroscience 2014; 277:610-23. [PMID: 25086314 DOI: 10.1016/j.neuroscience.2014.07.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 07/22/2014] [Indexed: 11/24/2022]
Abstract
Homeostatic plasticity is engaged when neurons need to stabilize their synaptic strength and excitability in response to acute or prolonged destabilizing changes in global activity. Compared to the extensive studies investigating the molecular mechanisms for homeostatic synaptic plasticity, the mechanism underlying homeostatic intrinsic plasticity is largely unknown. Through whole-cell patch-clamp recording in low-density cultures of dissociated hippocampal neurons, we demonstrate here that prolonged activity blockade induced by the sodium channel blocker tetrodotoxin (TTX) leads to increased action potential firing rates. Conversely, prolonged activity enhancement induced by the A-type gamma-aminobutyric acid receptor antagonist bicuculline (BC) results in decreased firing rates. Prolonged activity enhancement also enhanced potassium (K(+)) current through Kv1 channels, suggesting that changes in K(+) current, in part, mediate stabilization of hippocampal neuronal excitability upon prolonged activity elevation. In contrast to the previous reports showing that L-type voltage-gated calcium (Ca(2+)) channels solely mediate homeostatic regulation of excitatory synaptic strength (Ibata et al., 2008; Goold and Nicoll, 2010), inhibition of N-Methyl-d-aspartate (NMDA) receptors alone mimics the elevation in firing frequency driven by prolonged TTX application, while the decrease in firing rates induced by prolonged BC treatment involves the activity of NMDA receptors and L-type voltage-gated Ca(2+) channels. These results collectively provide strong evidence that alterations in Ca(2+) influx through NMDA receptors and L-type voltage-gated Ca(2+) channels mediate homeostatic intrinsic plasticity in hippocampal neurons in response to prolonged activity changes.
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Hacohen Y, Absoud M, Woodhall M, Cummins C, De Goede CG, Hemingway C, Jardine PE, Kneen R, Pike MG, Whitehouse WP, Wassmer E, Waters P, Vincent A, Lim M. Autoantibody biomarkers in childhood-acquired demyelinating syndromes: results from a national surveillance cohort. J Neurol Neurosurg Psychiatry 2014; 85:456-61. [PMID: 24133290 DOI: 10.1136/jnnp-2013-306411] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Autoantibodies to glial, myelin and neuronal antigens have been reported in a range of central demyelination syndromes and autoimmune encephalopathies in children, but there has not been a systematic evaluation across the range of central nervous system (CNS) autoantibodies in childhood-acquired demyelinating syndromes (ADS). METHODS Children under the age of 16 years with first-episode ADS were identified from a national prospective surveillance study; serum from 65 patients had been sent for a variety of diagnostic tests. Antibodies to astrocyte, myelin and neuronal antigens were tested or retested in all samples. RESULTS Fifteen patients (23%) were positive for at least one antibody (Ab): AQ4-Ab was detected in three; two presenting with neuromyelitis optica (NMO) and one with isolated optic neuritis (ON). Myelin oligodendrocyte glycoprotein (MOG)-Ab was detected in seven; two with acute disseminated encephalomyelitis (ADEM), two with ON, one with transverse myelitis (TM) and two with clinically isolated syndrome (CIS). N-Methyl-D-Aspartate receptor (NMDAR)-Ab was found in two; one presenting with ADEM and one with ON. Voltage-gated potassium channel (VGKC)-complex antibodies were positive in three; one presenting with ADEM, one with ON and one with CIS. GlyR-Ab was detected in one patient with TM. All patients were negative for the VGKC-complex-associated proteins LGI1, CASPR2 and contactin-2. CONCLUSIONS A range of CNS-directed autoantibodies were found in association with childhood ADS. Although these antibodies are clinically relevant when associated with the specific neurological syndromes that have been described, further studies are required to evaluate their roles and clinical relevance in demyelinating diseases.
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Affiliation(s)
- Yael Hacohen
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, , Oxford, UK
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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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25
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Kaliakatsos M, Hacohen Y, Siddiqui A, Dlamini N, Vincent A, Lim M. Acute disseminated encephalomyelitis associated with positive voltage gated potassium channel complex antibody. Mult Scler Relat Disord 2013; 2:147-50. [DOI: 10.1016/j.msard.2012.09.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 09/28/2012] [Accepted: 09/28/2012] [Indexed: 11/16/2022]
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26
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Moldovan M, Alvarez S, Romer Rosberg M, Krarup C. Axonal voltage-gated ion channels as pharmacological targets for pain. Eur J Pharmacol 2013; 708:105-12. [PMID: 23500193 DOI: 10.1016/j.ejphar.2013.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 03/04/2013] [Indexed: 12/19/2022]
Abstract
Upon peripheral nerve injury (caused by trauma or disease process) axons of the dorsal root ganglion (DRG) somatosensory neurons have the ability to sprout and regrow/remyelinate to reinnervate distant target tissue or form a tangled scar mass called a neuroma. This regenerative response can become maladaptive leading to a persistent and debilitating pain state referred to as chronic pain corresponding to the clinical description of neuropathic/chronic inflammatory pain. There is little agreement to what causes peripheral chronic pain other than hyperactivity of the nociceptive DRG neurons which ultimately depends on the function of voltage-gated ion channels. This review focuses on the pharmacological modulators of voltage-gated ion channels known to be present on axonal membrane which represents by far the largest surface of DRG neurons. Blockers of voltage-gated Na(+) channels, openers of voltage-gated K(+) channels and blockers of hyperpolarization-activated cyclic nucleotide-gated channels that were found to reduce neuronal activity were also found to be effective in neuropathic and inflammatory pain states. The isoforms of these channels present on nociceptive axons have limited specificity. The rationale for considering axonal voltage-gated ion channels as targets for pain treatment comes from the accumulating evidence that chronic pain states are associated with a dysregulation of these channels that could alter their specificity and make them more susceptible to pharmacological modulation. This drives the need for further development of subtype-specific voltage-gated ion channels modulators, as well as clinically available neurophysiological techniques for monitoring axonal ion channel function in peripheral nerves.
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Affiliation(s)
- Mihai Moldovan
- Institute of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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27
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Sánchez-Ponce D, DeFelipe J, Garrido JJ, Muñoz A. Developmental expression of Kv potassium channels at the axon initial segment of cultured hippocampal neurons. PLoS One 2012; 7:e48557. [PMID: 23119056 PMCID: PMC3485302 DOI: 10.1371/journal.pone.0048557] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 09/27/2012] [Indexed: 11/18/2022] Open
Abstract
Axonal outgrowth and the formation of the axon initial segment (AIS) are early events in the acquisition of neuronal polarity. The AIS is characterized by a high concentration of voltage-dependent sodium and potassium channels. However, the specific ion channel subunits present and their precise localization in this axonal subdomain vary both during development and among the types of neurons, probably determining their firing characteristics in response to stimulation. Here, we characterize the developmental expression of different subfamilies of voltage-gated potassium channels in the AISs of cultured mouse hippocampal neurons, including subunits Kv1.2, Kv2.2 and Kv7.2. In contrast to the early appearance of voltage-gated sodium channels and the Kv7.2 subunit at the AIS, Kv1.2 and Kv2.2 subunits were tethered at the AIS only after 10 days in vitro. Interestingly, we observed different patterns of Kv1.2 and Kv2.2 subunit expression, with each confined to distinct neuronal populations. The accumulation of Kv1.2 and Kv2.2 subunits at the AIS was dependent on ankyrin G tethering, it was not affected by disruption of the actin cytoskeleton and it was resistant to detergent extraction, as described previously for other AIS proteins. This distribution of potassium channels in the AIS further emphasizes the heterogeneity of this structure in different neuronal populations, as proposed previously, and suggests corresponding differences in action potential regulation.
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Affiliation(s)
- Diana Sánchez-Ponce
- Department of Functional and Systems Neurobiology, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Department of Molecular, Cellular and Developmental Neurobiology, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Department of Cell Biology, Complutense University, Madrid, Spain
| | - Javier DeFelipe
- Department of Functional and Systems Neurobiology, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Juan José Garrido
- Department of Molecular, Cellular and Developmental Neurobiology, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
- * E-mail: (AM); (JJG)
| | - Alberto Muñoz
- Department of Functional and Systems Neurobiology, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
- Department of Cell Biology, Complutense University, Madrid, Spain
- * E-mail: (AM); (JJG)
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Li X, Zheng S, Dong X, Xiao J. 17β-Estradiol inhibits outward voltage-gated K⁺ currents in human osteoblast-like MG63 cells. J Membr Biol 2012; 246:39-45. [PMID: 22976040 DOI: 10.1007/s00232-012-9502-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 08/29/2012] [Indexed: 11/29/2022]
Abstract
Previous studies have shown that 17β-estradiol has a pivotal function by blocking voltage-gated K⁺ (Kv) channels in several different types of cells such as cardiac myocytes and neurons. Outward Kv currents can also be measured in osteoblasts, although little is known about the effects of 17β-estradiol on these currents. In human osteoblast-like MG63 cells, we found that 17β-estradiol inhibits peak and end Kv currents, with IC₅₀ values of 480 and 325 nM, respectively. To elucidate the mechanism of inhibition, the kinetics of Kv currents were investigated. The half-maximum activation potential (V(½)) was 1.3 mV and was shifted left to -4.4 mV after application of 500 nM 17β-estradiol. For steady-state inactivation, the V(½) was -55.0 mV and weakly shifted left to -58.2 mV. To identify the molecular basis of outward Kv currents in MG63 cells, we performed RT-PCR analyses. The expression of Kv2.1 channels appeared to dominate over that of other Kv channels in MG63 cells. In COS-7 cells with heterologously expressed Kv2.1 channels, 17β-estradiol also inhibits macroscopic currents of Kv2.1. Our data indicate that 17β-estradiol inhibits Kv currents in human osteoblast-like MG63 cells and that Kv2.1 is a potential molecular correlate of outward Kv currents in these cells.
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Affiliation(s)
- Xiantao Li
- College of Biomedical Engineering, South-Central University for Nationalities, 708 Minyuan Road, Wuhan 430074, People's Republic of China
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29
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Buchner DA, Geisinger JM, Glazebrook PA, Morgan MG, Spiezio SH, Kaiyala KJ, Schwartz MW, Sakurai T, Furley AJ, Kunze DL, Croniger CM, Nadeau JH. The juxtaparanodal proteins CNTNAP2 and TAG1 regulate diet-induced obesity. Mamm Genome 2012; 23:431-42. [PMID: 22752552 DOI: 10.1007/s00335-012-9400-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 05/21/2012] [Indexed: 11/26/2022]
Abstract
Despite considerable effort, the identification of genes that regulate complex multigenic traits such as obesity has proven difficult with conventional methodologies. The use of a chromosome substitution strain-based mapping strategy based on deep congenic analysis overcame many of the difficulties associated with gene discovery and led to the finding that the juxtaparanodal proteins CNTNAP2 and TAG1 regulate diet-induced obesity. The effects of a mild Cntnap2 mutation on body weight were highly dependent on genetic background, as both obesity-promoting and obesity-resistant effects of Cntnap2 were observed on different genetic backgrounds. The more severe effect of complete TAG1 deficiency, by decreasing food intake, completely prevented the weight gain normally associated with high-fat-diet feeding. Together, these studies implicate two novel proteins in the regulation of diet-induced obesity. Moreover, as juxtaparanodal proteins have previously been implicated in various neurological disorders, our results suggest a potential genetic and molecular link between obesity and diseases such as autism and epilepsy.
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Affiliation(s)
- David A Buchner
- Department of Genetics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
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30
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Smith EJ, Xi W, Makarov D, Mönch I, Harazim S, Bolaños Quiñones VA, Schmidt CK, Mei Y, Sanchez S, Schmidt OG. Lab-in-a-tube: ultracompact components for on-chip capture and detection of individual micro-/nanoorganisms. LAB ON A CHIP 2012; 12:1917-31. [PMID: 22437345 DOI: 10.1039/c2lc21175k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A review of present and future on-chip rolled-up devices, which can be used to develop lab-in-a-tube total analysis systems, is presented. Lab-in-a-tube is the integration of numerous rolled-up components into a single device constituting a microsystem of hundreds/thousands of independent units on a chip, each individually capable of sorting, detecting and analyzing singular organisms. Such a system allows for a scale-down of biosensing systems, while at the same time increasing the data collection through a large, smart array of individual biosensors. A close look at these ultracompact components which have been developed over the past decade is given. Methods for the capture of biomaterial are laid out and progress of cell culturing in three-dimensional scaffolding is detailed. Rolled-up optical sensors based on photoluminescence, optomechanics, optofluidics and metamaterials are presented. Magnetic sensors are introduced as well as electrical components including heating, energy storage and resistor devices.
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Affiliation(s)
- Elliot J Smith
- Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany.
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31
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Desmazières A, Sol-Foulon N, Lubetzki C. Changes at the nodal and perinodal axonal domains: a basis for multiple sclerosis pathology? Mult Scler 2012; 18:133-7. [PMID: 22217583 DOI: 10.1177/1352458511434370] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
How axonal damage, a major prognostic factor of multiple sclerosis disability progression, is induced, is likely to be multifactorial. Whereas axonal injury has been identified as a consequence of myelin loss, the possibility of an additional direct damage is also suggested. In this context, recent data have highlighted the nodal and perinodal axonal domains of the myelinated neurons as potential targets of the disease process, opening new perspectives in multiple sclerosis pathophysiology.
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Affiliation(s)
- Anne Desmazières
- CRICM-UPMC/Inserm UMR_S 975/CNRS UMR 7225, Hôpital de la Salpêtrière, Paris, France
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32
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Differential subcellular distribution of ion channels and the diversity of neuronal function. Curr Opin Neurobiol 2011; 22:366-71. [PMID: 22033281 DOI: 10.1016/j.conb.2011.10.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/06/2011] [Accepted: 10/06/2011] [Indexed: 11/21/2022]
Abstract
Following the astonishing molecular diversity of voltage-gated ion channels that was revealed in the past few decades, the ion channel repertoire expressed by neurons has been implicated as the major factor governing their functional heterogeneity. Although the molecular structure of ion channels is a key determinant of their biophysical properties, their subcellular distribution and densities on the surface of nerve cells are just as important for fulfilling functional requirements. Recent results obtained with high resolution quantitative localization techniques revealed complex, subcellular compartment-specific distribution patterns of distinct ion channels. Here I suggest that within a given neuron type every ion channel has a unique cell surface distribution pattern, with the functional consequence that this dramatically increases the computational power of nerve cells.
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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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