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Teralı K, Türkyılmaz A, Sağer SG, Çebi AH. Prediction of molecular phenotypes for novel SCN1A variants from a Turkish genetic epilepsy syndromes cohort and report of two new patients with recessive Dravet syndrome. Clin Transl Sci 2024; 17:e13679. [PMID: 37955180 PMCID: PMC10772300 DOI: 10.1111/cts.13679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 09/23/2023] [Accepted: 09/29/2023] [Indexed: 11/14/2023] Open
Abstract
Dravet syndrome and genetic epilepsy with febrile seizures plus (GEFS+) are both epilepsy syndromes that can be attributed to deleterious mutations occurring in SCN1A, the gene encoding the pore-forming α-subunit of the NaV 1.1 voltage-gated sodium channel predominantly expressed in the central nervous system. In this research endeavor, our goal is to expand our prior cohort of Turkish patients affected by SCN1A-positive genetic epilepsy disorders. This will be accomplished by incorporating two recently discovered and infrequent index cases who possess a novel biallelic (homozygous) SCN1A missense variant, namely E158G, associated with Dravet syndrome. Furthermore, our intention is to use computational techniques to predict the molecular phenotypes of each distinct SCN1A variant that has been detected to date within our center. The correlation between genotype and phenotype in Dravet syndrome/GEFS+ is intricate and necessitates meticulous clinical investigation as well as advanced scientific exploration. Broadened mechanistic and structural insights into NaV 1.1 dysfunction offer significant promise in facilitating the development of targeted and effective therapies, which will ultimately enhance clinical outcomes in the treatment of epilepsy.
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Affiliation(s)
- Kerem Teralı
- Department of Medical Biochemistry, Faculty of MedicineCyprus International UniversityNicosiaCyprus
| | - Ayberk Türkyılmaz
- Department of Medical Genetics, Faculty of MedicineKaradeniz Technical UniversityTrabzonTurkey
| | - Safiye Güneş Sağer
- Department of Pediatric NeurologyKartal Dr. Lütfi Kırdar City HospitalİstanbulTurkey
| | - Alper Han Çebi
- Department of Medical Genetics, Faculty of MedicineKaradeniz Technical UniversityTrabzonTurkey
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Elleman AV, Du Bois J. Chemical and Biological Tools for the Study of Voltage-Gated Sodium Channels in Electrogenesis and Nociception. Chembiochem 2022; 23:e202100625. [PMID: 35315190 PMCID: PMC9359671 DOI: 10.1002/cbic.202100625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/22/2022] [Indexed: 12/17/2022]
Abstract
The malfunction and misregulation of voltage-gated sodium channels (NaV s) underlie in large part the electrical hyperexcitability characteristic of chronic inflammatory and neuropathic pain. NaV s are responsible for the initiation and propagation of electrical impulses (action potentials) in cells. Tissue and nerve injury alter the expression and localization of multiple NaV isoforms, including NaV 1.1, 1.3, and 1.6-1.9, resulting in aberrant action potential firing patterns. To better understand the role of NaV regulation, localization, and trafficking in electrogenesis and pain pathogenesis, a number of chemical and biological reagents for interrogating NaV function have been advanced. The development and application of such tools for understanding NaV physiology are the focus of this review.
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Affiliation(s)
- Anna V Elleman
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - J Du Bois
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
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Ravenscroft TA, Janssens J, Lee PT, Tepe B, Marcogliese PC, Makhzami S, Holmes TC, Aerts S, Bellen HJ. Drosophila Voltage-Gated Sodium Channels Are Only Expressed in Active Neurons and Are Localized to Distal Axonal Initial Segment-like Domains. J Neurosci 2020; 40:7999-8024. [PMID: 32928889 PMCID: PMC7574647 DOI: 10.1523/jneurosci.0142-20.2020] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 07/15/2020] [Accepted: 08/04/2020] [Indexed: 12/28/2022] Open
Abstract
In multipolar vertebrate neurons, action potentials (APs) initiate close to the soma, at the axonal initial segment. Invertebrate neurons are typically unipolar with dendrites integrating directly into the axon. Where APs are initiated in the axons of invertebrate neurons is unclear. Voltage-gated sodium (NaV) channels are a functional hallmark of the axonal initial segment in vertebrates. We used an intronic Minos-Mediated Integration Cassette to determine the endogenous gene expression and subcellular localization of the sole NaV channel in both male and female Drosophila, para Despite being the only NaV channel in the fly, we show that only 23 ± 1% of neurons in the embryonic and larval CNS express para, while in the adult CNS para is broadly expressed. We generated a single-cell transcriptomic atlas of the whole third instar larval brain to identify para expressing neurons and show that it positively correlates with markers of differentiated, actively firing neurons. Therefore, only 23 ± 1% of larval neurons may be capable of firing NaV-dependent APs. We then show that Para is enriched in an axonal segment, distal to the site of dendritic integration into the axon, which we named the distal axonal segment (DAS). The DAS is present in multiple neuron classes in both the third instar larval and adult CNS. Whole cell patch clamp electrophysiological recordings of adult CNS fly neurons are consistent with the interpretation that Nav-dependent APs originate in the DAS. Identification of the distal NaV localization in fly neurons will enable more accurate interpretation of electrophysiological recordings in invertebrates.SIGNIFICANCE STATEMENT The site of action potential (AP) initiation in invertebrates is unknown. We tagged the sole voltage-gated sodium (NaV) channel in the fly, para, and identified that Para is enriched at a distal axonal segment. The distal axonal segment is located distal to where dendrites impinge on axons and is the likely site of AP initiation. Understanding where APs are initiated improves our ability to model neuronal activity and our interpretation of electrophysiological data. Additionally, para is only expressed in 23 ± 1% of third instar larval neurons but is broadly expressed in adults. Single-cell RNA sequencing of the third instar larval brain shows that para expression correlates with the expression of active, differentiated neuronal markers. Therefore, only 23 ± 1% of third instar larval neurons may be able to actively fire NaV-dependent APs.
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Affiliation(s)
- Thomas A Ravenscroft
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Jasper Janssens
- VIB Center for Brain & Disease Research, KU Leuven, Leuven 3000, Belgium
- Department of Human Genetics, KU Leuven, Leuven 3000, Belgium
| | - Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Burak Tepe
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Paul C Marcogliese
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Samira Makhzami
- VIB Center for Brain & Disease Research, KU Leuven, Leuven 3000, Belgium
- Department of Human Genetics, KU Leuven, Leuven 3000, Belgium
| | - Todd C Holmes
- Department of Physiology and Biophysics, School of Medicine, University of California at Irvine, Irvine, California 92697
| | - Stein Aerts
- VIB Center for Brain & Disease Research, KU Leuven, Leuven 3000, Belgium
- Department of Human Genetics, KU Leuven, Leuven 3000, Belgium
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030
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Angus M, Peters CH, Poburko D, Brimble E, Spelbrink EM, Ruben PC. Case studies in neuroscience: a novel amino acid duplication in the NH 2-terminus of the brain sodium channel Na V1.1 underlying Dravet syndrome. J Neurophysiol 2019; 122:1975-1980. [PMID: 31533007 DOI: 10.1152/jn.00491.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dravet syndrome is a severe form of childhood epilepsy characterized by frequent temperature-sensitive seizures and delays in cognitive development. In the majority (80%) of cases, Dravet syndrome is caused by mutations in the SCN1A gene, encoding the voltage-gated sodium channel NaV1.1, which is abundant in the central nervous system. Dravet syndrome can be caused by either gain-of-function mutation or loss of function in NaV1.1, making it necessary to characterize each novel mutation. Here we use a combination of patch-clamp recordings and immunocytochemistry to characterize the first known NH2-terminal amino acid duplication mutation found in a patient with Dravet syndrome, M72dup. M72dup does not significantly alter rate of fast inactivation recovery or rate of fast inactivation onset at any measured membrane potential. M72dup significantly shifts the midpoint of the conductance voltage relationship to more hyperpolarized potentials. Most interestingly, M72dup significantly reduces peak current of NaV1.1 and reduces membrane expression. This suggests that M72dup acts as a loss-of-function mutation primarily by impacting the ability of the channel to localize to the plasma membrane.NEW & NOTEWORTHY Genetic screening of a patient with Dravet syndrome revealed a novel mutation in SCN1A. Of over 700 SCN1A mutations known to cause Dravet syndrome, M72dup is the first to be identified in the NH2-terminus of NaV1.1. We studied M72dup using patch-clamp electrophysiology and immunocytochemistry. M72dup causes a decrease in membrane expression of NaV1.1 and overall loss of function, consistent with the role of the NH2-terminal region in membrane trafficking of NaV1.1.
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Affiliation(s)
- Madeline Angus
- Department of Biomedical Physiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Colin H Peters
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Damon Poburko
- Department of Biomedical Physiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Elise Brimble
- Department of Neurology and Neurological Sciences, Stanford Medicine, Palo Alto, California
| | - Emily M Spelbrink
- Department of Neurology and Neurological Sciences, Stanford Medicine, Palo Alto, California
| | - Peter C Ruben
- Department of Biomedical Physiology, Simon Fraser University, Burnaby, British Columbia, Canada
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Salvatierra J, Diaz-Bustamante M, Meixiong J, Tierney E, Dong X, Bosmans F. A disease mutation reveals a role for NaV1.9 in acute itch. J Clin Invest 2018; 128:5434-5447. [PMID: 30395542 DOI: 10.1172/jci122481] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 09/20/2018] [Indexed: 02/02/2023] Open
Abstract
Itch (pruritis) and pain represent two distinct sensory modalities; yet both have evolved to alert us to potentially harmful external stimuli. Compared with pain, our understanding of itch is still nascent. Here, we report a new clinical case of debilitating itch and altered pain perception resulting from the heterozygous de novo p.L811P gain-of-function mutation in NaV1.9, a voltage-gated sodium (NaV) channel subtype that relays sensory information from the periphery to the spine. To investigate the role of NaV1.9 in itch, we developed a mouse line in which the channel is N-terminally tagged with a fluorescent protein, thereby enabling the reliable identification and biophysical characterization of NaV1.9-expressing neurons. We also assessed NaV1.9 involvement in itch by using a newly created NaV1.9-/- and NaV1.9L799P/WT mouse model. We found that NaV1.9 is expressed in a subset of nonmyelinated, nonpeptidergic small-diameter dorsal root ganglia (DRGs). In WT DRGs, but not those of NaV1.9-/- mice, pruritogens altered action potential parameters and NaV channel gating properties. Additionally, NaV1.9-/- mice exhibited a strong reduction in acute scratching behavior in response to pruritogens, whereas NaV1.9L799P/WT mice displayed increased spontaneous scratching. Altogether, our data suggest an important contribution of NaV1.9 to itch signaling.
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Affiliation(s)
| | | | | | | | - Xinzhong Dong
- Solomon H. Snyder Department of Neuroscience.,Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Frank Bosmans
- Department of Physiology.,Solomon H. Snyder Department of Neuroscience.,Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
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Abstract
Voltage-gated sodium channels (VGSC) are critical determinants of cellular electrical activity through the control of initiation and propagation of action potential. To ensure this role, these proteins are not consistently delivered to the plasma membrane but undergo drastic quality controls throughout various adaptive processes such as biosynthesis, anterograde and retrograde trafficking, and membrane targeting. In pathological conditions, this quality control could lead to the retention of functional VGSC and is therefore the target of different pharmacological approaches. The present chapter gives an overview of the current understanding of the facets of VGSC life cycle in the context of both cardiac and neuronal cell types.
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Affiliation(s)
- A Mercier
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
| | - P Bois
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
| | - A Chatelier
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France.
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Pablo JL, Wang C, Presby MM, Pitt GS. Polarized localization of voltage-gated Na+ channels is regulated by concerted FGF13 and FGF14 action. Proc Natl Acad Sci U S A 2016; 113:E2665-74. [PMID: 27044086 PMCID: PMC4868475 DOI: 10.1073/pnas.1521194113] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Clustering of voltage-gated sodium channels (VGSCs) within the neuronal axon initial segment (AIS) is critical for efficient action potential initiation. Although initially inserted into both somatodendritic and axonal membranes, VGSCs are concentrated within the axon through mechanisms that include preferential axonal targeting and selective somatodendritic endocytosis. How the endocytic machinery specifically targets somatic VGSCs is unknown. Here, using knockdown strategies, we show that noncanonical FGF13 binds directly to VGSCs in hippocampal neurons to limit their somatodendritic surface expression, although exerting little effect on VGSCs within the AIS. In contrast, homologous FGF14, which is highly concentrated in the proximal axon, binds directly to VGSCs to promote their axonal localization. Single-point mutations in FGF13 or FGF14 abrogating VGSC interaction in vitro cannot support these specific functions in neurons. Thus, our data show how the concerted actions of FGF13 and FGF14 regulate the polarized localization of VGSCs that supports efficient action potential initiation.
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Affiliation(s)
- Juan Lorenzo Pablo
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710; Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710
| | - Chaojian Wang
- Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710; Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710
| | - Matthew M Presby
- Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710; Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710
| | - Geoffrey S Pitt
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710; Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710; Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710
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Heterologous expression of NaV1.9 chimeras in various cell systems. Pflugers Arch 2015; 467:2423-35. [PMID: 25916202 DOI: 10.1007/s00424-015-1709-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 03/31/2015] [Accepted: 04/16/2015] [Indexed: 01/27/2023]
Abstract
SCN11A encodes the voltage-gated sodium channel NaV1.9, which deviates most strongly from the other eight NaV channels expressed in mammals. It is characterized by resistance to the prototypic NaV channel blocker tetrodotoxin and exhibits slow activation and inactivation gating. Its expression in dorsal root ganglia neurons suggests a role in motor or pain signaling functions as also recently demonstrated by the occurrence of various mutations in human SCN11A leading to altered pain sensation syndromes. The systematic investigation of human NaV1.9, however, is severely hampered because of very poor heterologous expression in host cells. Using patch-clamp and two-electrode voltage-clamp methods, we show that this limitation is caused by the C-terminal structure of NaV1.9. A chimera of NaV1.9 harboring the C terminus of NaV1.4 yields functional expression not only in neuronal cells but also in non-excitable cells, such as HEK 293T or Xenopus oocytes. The major functional difference of the chimeric channel with respect to NaV1.9 is an accelerated activation and inactivation. Since the entire transmembrane domain is preserved, it is suited for studying pharmacological properties of the channel and the functional impact of disease-causing mutations. Moreover, we demonstrate how mutation S360Y makes NaV1.9 channels sensitive to tetrodotoxin and saxitoxin and that the unusual slow open-state inactivation of NaV1.9 is also mediated by the IFM (isoleucine-phenylalanine-methionine) inactivation motif located in the linker connecting domains III and IV.
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9
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Akin EJ, Solé L, Dib-Hajj SD, Waxman SG, Tamkun MM. Preferential targeting of Nav1.6 voltage-gated Na+ Channels to the axon initial segment during development. PLoS One 2015; 10:e0124397. [PMID: 25874799 PMCID: PMC4398423 DOI: 10.1371/journal.pone.0124397] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 03/13/2015] [Indexed: 12/19/2022] Open
Abstract
During axonal maturation, voltage-gated sodium (Nav) channels accumulate at the axon initial segment (AIS) at high concentrations. This localization is necessary for the efficient initiation of action potentials. The mechanisms underlying channel trafficking to the AIS during axonal development have remained elusive due to a lack of Nav reagents suitable for high resolution imaging of channels located specifically on the cell surface. Using an optical pulse-chase approach in combination with a novel Nav1.6 construct containing an extracellular biotinylation domain we demonstrate that Nav1.6 channels are preferentially inserted into the AIS membrane during neuronal development via direct vesicular trafficking. Single-molecule tracking illustrates that axonal channels are immediately immobilized following delivery, while channels delivered to the soma are often mobile. Neither a Nav1.6 channel lacking the ankyrin-binding motif nor a chimeric Kv2.1 channel containing the Nav ankyrinG-binding domain show preferential AIS insertion. Together these data support a model where ankyrinG-binding is required for preferential Nav1.6 insertion into the AIS plasma membrane. In contrast, ankyrinG-binding alone does not confer the preferential delivery of proteins to the AIS.
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Affiliation(s)
- Elizabeth J Akin
- Cell and Molecular Biology Graduate Program, Colorado State University, Fort Collins, Colorado, United States of America; Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
| | - Laura Solé
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Sulayman D Dib-Hajj
- Rehabilitation Research Center, Veterans Administration Connecticut Healthcare System, West Haven, Connecticut, United States of America; Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Stephen G Waxman
- Rehabilitation Research Center, Veterans Administration Connecticut Healthcare System, West Haven, Connecticut, United States of America; Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Michael M Tamkun
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America; Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America; Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, United States of America
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Liu C, Tan FCK, Xiao ZC, Dawe GS. Amyloid precursor protein enhances Nav1.6 sodium channel cell surface expression. J Biol Chem 2015; 290:12048-57. [PMID: 25767117 DOI: 10.1074/jbc.m114.617092] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Indexed: 12/19/2022] Open
Abstract
Amyloid precursor protein (APP) is commonly associated with Alzheimer disease, but its physiological function remains unknown. Nav1.6 is a key determinant of neuronal excitability in vivo. Because mouse models of gain of function and loss of function of APP and Nav1.6 share some similar phenotypes, we hypothesized that APP might be a candidate molecule for sodium channel modulation. Here we report that APP colocalized and interacted with Nav1.6 in mouse cortical neurons. Knocking down APP decreased Nav1.6 sodium channel currents and cell surface expression. APP-induced increases in Nav1.6 cell surface expression were Go protein-dependent, enhanced by a constitutively active Go protein mutant, and blocked by a dominant negative Go protein mutant. APP also regulated JNK activity in a Go protein-dependent manner. JNK inhibition attenuated increases in cell surface expression of Nav1.6 sodium channels induced by overexpression of APP. JNK, in turn, phosphorylated APP. Nav1.6 sodium channel surface expression was increased by T668E and decreased by T668A, mutations of APP695 mimicking and preventing Thr-668 phosphorylation, respectively. Phosphorylation of APP695 at Thr-668 enhanced its interaction with Nav1.6. Therefore, we show that APP enhances Nav1.6 sodium channel cell surface expression through a Go-coupled JNK pathway.
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Affiliation(s)
- Chao Liu
- From the Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, the Neurobiology and Ageing Programme, Life Sciences Institute and Singapore Institute for Neurotechnology (SINAPSE), Centre for Life Sciences, National University of Singapore, 28 Medical Drive, Singapore 117456
| | - Francis Chee Kuan Tan
- From the Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, the Neurobiology and Ageing Programme, Life Sciences Institute and Singapore Institute for Neurotechnology (SINAPSE), Centre for Life Sciences, National University of Singapore, 28 Medical Drive, Singapore 117456
| | - Zhi-Cheng Xiao
- the Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical College, Kunming 650031, China, and the Shunxi-Monash Immune Regeneration and Neuroscience Laboratories, Department of Anatomy and Developmental Biology, Monash University, Clayton, Melbourne, Victoria 3800, Australia
| | - Gavin S Dawe
- From the Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, the Neurobiology and Ageing Programme, Life Sciences Institute and Singapore Institute for Neurotechnology (SINAPSE), Centre for Life Sciences, National University of Singapore, 28 Medical Drive, Singapore 117456,
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Barry J, Gu Y, Jukkola P, O'Neill B, Gu H, Mohler PJ, Rajamani KT, Gu C. Ankyrin-G directly binds to kinesin-1 to transport voltage-gated Na+ channels into axons. Dev Cell 2014; 28:117-31. [PMID: 24412576 DOI: 10.1016/j.devcel.2013.11.023] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 10/14/2013] [Accepted: 11/26/2013] [Indexed: 12/26/2022]
Abstract
Action potentials (APs) propagating along axons require the activation of voltage-gated Na(+) (Nav) channels. How Nav channels are transported into axons is unknown. We show that KIF5/kinesin-1 directly binds to ankyrin-G (AnkG) to transport Nav channels into axons. KIF5 and Nav1.2 channels bind to multiple sites in the AnkG N-terminal domain that contains 24 ankyrin repeats. Disrupting AnkG-KIF5 binding with small interfering RNA or dominant-negative constructs markedly reduced Nav channel levels at the axon initial segment (AIS) and along entire axons, thereby decreasing AP firing. Live-cell imaging showed that fluorescently tagged AnkG or Nav1.2 cotransported with KIF5 along axons. Deleting AnkG in vivo or virus-mediated expression of a dominant-negative KIF5 construct specifically decreased the axonal level of Nav, but not Kv1.2, channels in mouse cerebellum. These results indicate that AnkG functions as an adaptor to link Nav channels to KIF5 during axonal transport before anchoring them to the AIS and nodes of Ranvier.
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Affiliation(s)
- Joshua Barry
- Molecular, Cellular and Developmental Biology Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Yuanzheng Gu
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA
| | - Peter Jukkola
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Brian O'Neill
- Department of Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Howard Gu
- Department of Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Peter J Mohler
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA; Departments of Internal Medicine and Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA
| | | | - Chen Gu
- Molecular, Cellular and Developmental Biology Graduate Program, The Ohio State University, Columbus, OH 43210, USA; Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA; Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH 43210, USA.
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Zhang Y, Bekku Y, Dzhashiashvili Y, Armenti S, Meng X, Sasaki Y, Milbrandt J, Salzer JL. Assembly and maintenance of nodes of ranvier rely on distinct sources of proteins and targeting mechanisms. Neuron 2012; 73:92-107. [PMID: 22243749 DOI: 10.1016/j.neuron.2011.10.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2011] [Indexed: 01/29/2023]
Abstract
VIDEO ABSTRACT We have investigated the source(s) and targeting of components to PNS nodes of Ranvier. We show adhesion molecules are freely diffusible within the axon membrane and accumulate at forming nodes from local sources, whereas ion channels and cytoskeletal components are largely immobile and require transport to the node. We further characterize targeting of NF186, an adhesion molecule that pioneers node formation. NF186 redistributes to nascent nodes from a mobile, surface pool. Its initial accumulation and clearance from the internode require extracellular interactions, whereas targeting to mature nodes, i.e., those flanked by paranodal junctions, requires intracellular interactions. After incorporation into the node, NF186 is immobile, stable, and promotes node integrity. Thus, nodes assemble from two sources: adhesion molecules, which initiate assembly, accumulate by diffusion trapping via interactions with Schwann cells, whereas ion channels and cytoskeletal components accumulate via subsequent transport. In mature nodes, components turnover slowly and are replenished via transport.
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Affiliation(s)
- Yanqing Zhang
- Smilow Neuroscience Program, New York University Langone Medical Center, New York, NY 10016, USA
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