1
|
Varadi G. Mechanism of Analgesia by Gabapentinoid Drugs: Involvement of Modulation of Synaptogenesis and Trafficking of Glutamate-Gated Ion Channels. J Pharmacol Exp Ther 2024; 388:121-133. [PMID: 37918854 DOI: 10.1124/jpet.123.001669] [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: 06/09/2023] [Revised: 10/18/2023] [Accepted: 10/23/2023] [Indexed: 11/04/2023] Open
Abstract
Gabapentinoids have clinically been used for treating epilepsy, neuropathic pain, and several other neurologic disorders for >30 years; however, the definitive molecular mechanism responsible for their therapeutic actions remained uncertain. The conventional pharmacological observation regarding their efficacy in chronic pain modulation is the weakening of glutamate release at presynaptic terminals in the spinal cord. While the α2/δ-1 subunit of voltage-gated calcium channels (VGCCs) has been identified as the primary drug receptor for gabapentinoids, the lack of consistent effect of this drug class on VGCC function is indicative of a minor role in regulating this ion channel's activity. The current review targets the efficacy and mechanism of gabapentinoids in treating chronic pain. The discovery of interaction of α2/δ-1 with thrombospondins established this protein as a major synaptogenic neuronal receptor for thrombospondins. Other findings identified α2/δ-1 as a powerful regulator of N-methyl-D-aspartate receptor (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) by potentiating the synaptic expression, a putative pathophysiological mechanism of neuropathic pain. Further, the interdependent interactions between thrombospondin and α2/δ-1 contribute to chronic pain states, while gabapentinoid ligands efficaciously reverse such pain conditions. Gabapentin normalizes and even blocks NMDAR and AMPAR synaptic targeting and activity elicited by nerve injury. SIGNIFICANCE STATEMENT: Gabapentinoid drugs are used to treat various neurological conditions including chronic pain. In chronic pain states, gene expression of cacnα2/δ-1 and thrombospondins are upregulated and promote aberrant excitatory synaptogenesis. The complex trait of protein associations that involve interdependent interactions between α2/δ-1 and thrombospondins, further, association of N-methyl-D-aspartate receptor and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor with the C-tail of α2/δ-1, constitutes a macromolecular signaling complex that forms the crucial elements for the pharmacological mode of action of gabapentinoids.
Collapse
|
2
|
Page KM, Gumerov VM, Dahimene S, Zhulin IB, Dolphin AC. The importance of cache domains in α 2δ proteins and the basis for their gabapentinoid selectivity. Channels (Austin) 2023; 17:2167563. [PMID: 36735378 PMCID: PMC9901441 DOI: 10.1080/19336950.2023.2167563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In this hybrid review, we have first collected and reviewed available information on the structure and function of the enigmatic cache domains in α2δ proteins. These are organized into two double cache (dCache_1) domains, and they are present in all α2δ proteins. We have also included new data on the key function of these domains with respect to amino acid and gabapentinoid binding to the universal amino acid-binding pocket, which is present in α2δ-1 and α2δ-2. We have now identified the reason why α2δ-3 and α2δ-4 do not bind gabapentinoid drugs or amino acids with bulky side chains. In relation to this, we have determined that the bulky amino acids Tryptophan and Phenylalanine prevent gabapentin from inhibiting cell surface trafficking of α2δ-1. Together, these novel data shed further light on the importance of the cache domains in α2δ proteins.
Collapse
Affiliation(s)
- Karen M Page
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Vadim M Gumerov
- Department of Microbiology and Translational Data Analytics Institute, The Ohio State University, Columbus, OH, USA
| | - Shehrazade Dahimene
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Igor B Zhulin
- Department of Microbiology and Translational Data Analytics Institute, The Ohio State University, Columbus, OH, USA
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
- CONTACT Annette C Dolphin Dolphin Department of Neuroscience, Physiology and Pharmacology, University College London, LondonWC1E 6BT, UK
| |
Collapse
|
3
|
Catterall WA. Voltage gated sodium and calcium channels: Discovery, structure, function, and Pharmacology. Channels (Austin) 2023; 17:2281714. [PMID: 37983307 PMCID: PMC10761118 DOI: 10.1080/19336950.2023.2281714] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 10/11/2023] [Indexed: 11/22/2023] Open
Abstract
Voltage-gated sodium channels initiate action potentials in nerve and muscle, and voltage-gated calcium channels couple depolarization of the plasma membrane to intracellular events such as secretion, contraction, synaptic transmission, and gene expression. In this Review and Perspective article, I summarize early work that led to identification, purification, functional reconstitution, and determination of the amino acid sequence of the protein subunits of sodium and calcium channels and showed that their pore-forming subunits are closely related. Decades of study by antibody mapping, site-directed mutagenesis, and electrophysiological recording led to detailed two-dimensional structure-function maps of the amino acid residues involved in voltage-dependent activation and inactivation, ion permeation and selectivity, and pharmacological modulation. Most recently, high-resolution three-dimensional structure determination by X-ray crystallography and cryogenic electron microscopy has revealed the structural basis for sodium and calcium channel function and pharmacological modulation at the atomic level. These studies now define the chemical basis for electrical signaling and provide templates for future development of new therapeutic agents for a range of neurological and cardiovascular diseases.
Collapse
|
4
|
Bartels P, Salveson I, Coleman AM, Anderson DE, Jeng G, Estrada-Tobar ZM, Man KNM, Yu Q, Kuzmenkina E, Nieves-Cintron M, Navedo MF, Horne MC, Hell JW, Ames JB. Half-calcified calmodulin promotes basal activity and inactivation of the L-type calcium channel Ca V1.2. J Biol Chem 2022; 298:102701. [PMID: 36395884 PMCID: PMC9764201 DOI: 10.1016/j.jbc.2022.102701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 11/17/2022] Open
Abstract
The L-type Ca2+ channel CaV1.2 controls gene expression, cardiac contraction, and neuronal activity. Calmodulin (CaM) governs CaV1.2 open probability (Po) and Ca2+-dependent inactivation (CDI) but the mechanisms remain unclear. Here, we present electrophysiological data that identify a half Ca2+-saturated CaM species (Ca2/CaM) with Ca2+ bound solely at the third and fourth EF-hands (EF3 and EF4) under resting Ca2+ concentrations (50-100 nM) that constitutively preassociates with CaV1.2 to promote Po and CDI. We also present an NMR structure of a complex between the CaV1.2 IQ motif (residues 1644-1665) and Ca2/CaM12', a calmodulin mutant in which Ca2+ binding to EF1 and EF2 is completely disabled. We found that the CaM12' N-lobe does not interact with the IQ motif. The CaM12' C-lobe bound two Ca2+ ions and formed close contacts with IQ residues I1654 and Y1657. I1654A and Y1657D mutations impaired CaM binding, CDI, and Po, as did disabling Ca2+ binding to EF3 and EF4 in the CaM34 mutant when compared to WT CaM. Accordingly, a previously unappreciated Ca2/CaM species promotes CaV1.2 Po and CDI, identifying Ca2/CaM as an important mediator of Ca signaling.
Collapse
Affiliation(s)
- Peter Bartels
- Department of Pharmacology, University of California, Davis, California, USA
| | - Ian Salveson
- Department of Chemistry, University of California, Davis, California, USA
| | - Andrea M Coleman
- Department of Pharmacology, University of California, Davis, California, USA; Department of Chemistry, University of California, Davis, California, USA
| | - David E Anderson
- Department of Chemistry, University of California, Davis, California, USA
| | - Grace Jeng
- Department of Pharmacology, University of California, Davis, California, USA
| | | | - Kwun Nok Mimi Man
- Department of Pharmacology, University of California, Davis, California, USA
| | - Qinhong Yu
- Department of Chemistry, University of California, Davis, California, USA
| | - Elza Kuzmenkina
- Center for Pharmacology, University of Cologne, Cologne, Germany
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, California, USA
| | - Mary C Horne
- Department of Pharmacology, University of California, Davis, California, USA.
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, California, USA.
| | - James B Ames
- Department of Chemistry, University of California, Davis, California, USA.
| |
Collapse
|
5
|
Convergent regulation of Ca V1.2 channels by direct phosphorylation and by the small GTPase RAD in the cardiac fight-or-flight response. Proc Natl Acad Sci U S A 2022; 119:e2208533119. [PMID: 36215501 PMCID: PMC9586275 DOI: 10.1073/pnas.2208533119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The L-type calcium currents conducted by the cardiac CaV1.2 calcium channel initiate excitation-contraction coupling and serve as a key regulator of heart rate, rhythm, and force of contraction. CaV1.2 is regulated by β-adrenergic/protein kinase A (PKA)-mediated protein phosphorylation, proteolytic processing, and autoinhibition by its carboxyl-terminal domain (CT). The small guanosine triphosphatase (GTPase) RAD (Ras associated with diabetes) has emerged as a potent inhibitor of CaV1.2, and accumulating evidence suggests a key role for RAD in mediating β-adrenergic/PKA upregulation of channel activity. However, the relative roles of direct phosphorylation of CaV1.2 channels and phosphorylation of RAD in channel regulation remain uncertain. Here, we investigated the hypothesis that these two mechanisms converge to regulate CaV1.2 channels. Both RAD and the proteolytically processed distal CT (dCT) strongly reduced CaV1.2 activity. PKA phosphorylation of RAD and phosphorylation of Ser-1700 in the proximal CT (pCT) synergistically reversed this inhibition and increased CaV1.2 currents. Our findings reveal that the proteolytically processed form of CaV1.2 undergoes convergent regulation by direct phosphorylation of the CT and by phosphorylation of RAD. These parallel regulatory pathways provide a flexible mechanism for upregulation of the activity of CaV1.2 channels in the fight-or-flight response.
Collapse
|
6
|
Tei Y, Mikami Y, Ito M, Tomida T, Ohshima D, Hori Y, Adachi-Akahane S. Pathogenic Mechanism of Dry Eye-Induced Chronic Ocular Pain and a Mechanism-Based Therapeutic Approach. Invest Ophthalmol Vis Sci 2022; 63:7. [PMID: 34989761 PMCID: PMC8742529 DOI: 10.1167/iovs.63.1.7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Purpose Dry eye–induced chronic ocular pain is also called ocular neuropathic pain. However, details of the pathogenic mechanism remain unknown. The purpose of this study was to elucidate the pathogenic mechanism of dry eye–induced chronic pain in the anterior eye area and develop a pathophysiology-based therapeutic strategy. Methods We used a rat dry eye model with lacrimal gland excision (LGE) to elucidate the pathogenic mechanism of ocular neuropathic pain. Corneal epithelial damage, hypersensitivity, and hyperalgesia were evaluated on the LGE side and compared with the sham surgery side. We analyzed neuronal activity, microglial and astrocytic activity, α2δ–1 subunit expression, and inhibitory interneurons in the trigeminal nucleus. We also evaluated the therapeutic effects of ophthalmic treatment and chronic pregabalin administration on dry eye–induced ocular neuropathic pain. Results Dry eye caused hypersensitivity and hyperalgesia on the LGE side. In the trigeminal nucleus of the LGE side, neuronal hyperactivation, transient activation of microglia, persistent activation of astrocytes, α2δ–1 subunit upregulation, and reduced numbers of inhibitory interneurons were observed. Ophthalmic treatment alone did not improve hyperalgesia. In contrast, continuous treatment with pregabalin effectively ameliorated hypersensitivity and hyperalgesia and normalized neural activity, α2δ–1 subunit upregulation, and astrocyte activation. Conclusions These results suggest that dry eye–induced hypersensitivity and hyperalgesia are caused by central sensitization in the trigeminal nucleus with upregulation of the α2δ–1 subunit. Here, we showed that pregabalin is effective for treating dry eye–induced ocular neuropathic pain even after chronic pain has been established.
Collapse
Affiliation(s)
- Yuto Tei
- Department of Ophthalmology, Toho University Graduate School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Faculty of Medicine, Toho University, Tokyo, Japan.,Department of Physiology, Toho University Graduate School of Medicine, Tokyo, Japan
| | - Yoshinori Mikami
- Department of Physiology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Masanori Ito
- Department of Physiology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Taichiro Tomida
- Department of Physiology, Toho University Graduate School of Medicine, Tokyo, Japan.,Department of Physiology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Daisuke Ohshima
- Department of Physiology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Yuichi Hori
- Department of Ophthalmology, Toho University Graduate School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Satomi Adachi-Akahane
- Department of Physiology, Toho University Graduate School of Medicine, Tokyo, Japan.,Department of Physiology, Faculty of Medicine, Toho University, Tokyo, Japan
| |
Collapse
|
7
|
How Postdoctoral Research in Paul Greengard's Laboratory Shaped My Scientific Career, Although I Never Did Another Phosphorylation Assay. J Neurosci 2021; 41:2070-2075. [PMID: 33558431 PMCID: PMC8018760 DOI: 10.1523/jneurosci.3002-20.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/21/2021] [Accepted: 01/26/2021] [Indexed: 11/21/2022] Open
Abstract
In this short review, I describe from personal experience how every step in the career of any scientist, no matter how disjointed and pragmatic each might seem at the time, will almost inevitably meld together, to help us all tackle novel projects. My postdoctoral research in Paul Greengard's laboratory, where I investigated neurotransmitter-mediated phosphorylation of Synapsin I, was instrumental in my career progression, and Paul's support was instrumental in my ability to make a leap into independent research.
Collapse
|
8
|
Geisler SM, Benedetti A, Schöpf CL, Schwarzer C, Stefanova N, Schwartz A, Obermair GJ. Phenotypic Characterization and Brain Structure Analysis of Calcium Channel Subunit α 2δ-2 Mutant (Ducky) and α 2δ Double Knockout Mice. Front Synaptic Neurosci 2021; 13:634412. [PMID: 33679366 PMCID: PMC7933509 DOI: 10.3389/fnsyn.2021.634412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 01/11/2021] [Indexed: 01/19/2023] Open
Abstract
Auxiliary α2δ subunits of voltage-gated calcium channels modulate channel trafficking, current properties, and synapse formation. Three of the four isoforms (α2δ-1, α2δ-2, and α2δ-3) are abundantly expressed in the brain; however, of the available knockout models, only α2δ-2 knockout or mutant mice display an obvious abnormal neurological phenotype. Thus, we hypothesize that the neuronal α2δ isoforms may have partially specific as well as redundant functions. To address this, we generated three distinct α2δ double knockout mouse models by crossbreeding single knockout (α2δ-1 and -3) or mutant (α2δ-2/ducky) mice. Here, we provide a first phenotypic description and brain structure analysis. We found that genotypic distribution of neonatal litters in distinct α2δ-1/-2, α2δ-1/-3, and α2δ-2/-3 breeding combinations did not conform to Mendel's law, suggesting premature lethality of single and double knockout mice. Notably, high occurrences of infant mortality correlated with the absence of specific α2δ isoforms (α2Δ-2 > α2δ-1 > α2δ-3), and was particularly observed in cages with behaviorally abnormal parenting animals of α2δ-2/-3 cross-breedings. Juvenile α2δ-1/-2 and α2δ-2/-3 double knockout mice displayed a waddling gate similar to ducky mice. However, in contrast to ducky and α2δ-1/-3 double knockout animals, α2δ-1/-2 and α2δ-2/-3 double knockout mice showed a more severe disease progression and highly impaired development. The observed phenotypes within the individual mouse lines may be linked to differences in the volume of specific brain regions. Reduced cortical volume in ducky mice, for example, was associated with a progressively decreased space between neurons, suggesting a reduction of total synaptic connections. Taken together, our findings show that α2δ subunits differentially regulate premature survival, postnatal growth, brain development, and behavior, suggesting specific neuronal functions in health and disease.
Collapse
Affiliation(s)
- Stefanie M. Geisler
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Ariane Benedetti
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Clemens L. Schöpf
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Nadia Stefanova
- Division of Neurobiology, Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
| | - Arnold Schwartz
- Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Gerald J. Obermair
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
- Division Physiology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
| |
Collapse
|
9
|
Shabbir W. T1143 essential for Ca V1.2 inhibition by diltiazem. Eur J Pharmacol 2021; 895:173889. [PMID: 33482177 DOI: 10.1016/j.ejphar.2021.173889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 01/07/2021] [Accepted: 01/13/2021] [Indexed: 11/15/2022]
Abstract
Careful analysis of previously published reports and some new insights into the structure activity studies revealed an important role of Threonine 1143 in drug binding. Substituting T1143 by alanine and other residues significantly reduced channel inhibition by qDil and Dil. Mutation T1143A did not affect channel activation or inactivation while almost completely diminishing channel block by Dil or qDil. These findings support the view that T1143 serves as drug binding determinant. Other mutations in this position than T1143A (T1143L/Y/S/N/C/V/E) diminished channel inhibition by qDil but additionally affected channel activation and inactivation and may therefore affect channel block allosterically. Collectively, our data suggest that T1143 is an essential diltiazem binding determinant.
Collapse
Affiliation(s)
- Waheed Shabbir
- Institute for Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
| |
Collapse
|
10
|
Dolphin AC, Lee A. Presynaptic calcium channels: specialized control of synaptic neurotransmitter release. Nat Rev Neurosci 2020; 21:213-229. [PMID: 32161339 PMCID: PMC7873717 DOI: 10.1038/s41583-020-0278-2] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2020] [Indexed: 11/09/2022]
Abstract
Chemical synapses are heterogeneous junctions formed between neurons that are specialized for the conversion of electrical impulses into the exocytotic release of neurotransmitters. Voltage-gated Ca2+ channels play a pivotal role in this process as they are the major conduits for the Ca2+ ions that trigger the fusion of neurotransmitter-containing vesicles with the presynaptic membrane. Alterations in the intrinsic function of these channels and their positioning within the active zone can profoundly alter the timing and strength of synaptic output. Advances in optical and electron microscopic imaging, structural biology and molecular techniques have facilitated recent breakthroughs in our understanding of the properties of voltage-gated Ca2+ channels that support their presynaptic functions. Here we examine the nature of these channels, how they are trafficked to and anchored within presynaptic boutons, and the mechanisms that allow them to function optimally in shaping the flow of information through neural circuits.
Collapse
Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA.
| |
Collapse
|
11
|
Turner M, Anderson DE, Bartels P, Nieves-Cintron M, Coleman AM, Henderson PB, Man KNM, Tseng PY, Yarov-Yarovoy V, Bers DM, Navedo MF, Horne MC, Ames JB, Hell JW. α-Actinin-1 promotes activity of the L-type Ca 2+ channel Ca v 1.2. EMBO J 2020; 39:e102622. [PMID: 31985069 DOI: 10.15252/embj.2019102622] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 12/04/2019] [Accepted: 12/06/2019] [Indexed: 01/05/2023] Open
Abstract
The L-type Ca2+ channel CaV 1.2 governs gene expression, cardiac contraction, and neuronal activity. Binding of α-actinin to the IQ motif of CaV 1.2 supports its surface localization and postsynaptic targeting in neurons. We report a bi-functional mechanism that restricts CaV 1.2 activity to its target sites. We solved separate NMR structures of the IQ motif (residues 1,646-1,664) bound to α-actinin-1 and to apo-calmodulin (apoCaM). The CaV 1.2 K1647A and Y1649A mutations, which impair α-actinin-1 but not apoCaM binding, but not the F1658A and K1662E mutations, which impair apoCaM but not α-actinin-1 binding, decreased single-channel open probability, gating charge movement, and its coupling to channel opening. Thus, α-actinin recruits CaV 1.2 to defined surface regions and simultaneously boosts its open probability so that CaV 1.2 is mostly active when appropriately localized.
Collapse
Affiliation(s)
- Matthew Turner
- Department of Chemistry, University of California, Davis, CA, USA
| | - David E Anderson
- Department of Chemistry, University of California, Davis, CA, USA
| | - Peter Bartels
- Department of Pharmacology, University of California, Davis, CA, USA
| | | | - Andrea M Coleman
- Department of Chemistry, University of California, Davis, CA, USA.,Department of Pharmacology, University of California, Davis, CA, USA
| | - Peter B Henderson
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Kwun Nok Mimi Man
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Pang-Yen Tseng
- Department of Pharmacology, University of California, Davis, CA, USA
| | | | - Donald M Bers
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Mary C Horne
- Department of Pharmacology, University of California, Davis, CA, USA
| | - James B Ames
- Department of Chemistry, University of California, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, CA, USA
| |
Collapse
|
12
|
Dahimene S, Page KM, Kadurin I, Ferron L, Ho DY, Powell GT, Pratt WS, Wilson SW, Dolphin AC. The α 2δ-like Protein Cachd1 Increases N-type Calcium Currents and Cell Surface Expression and Competes with α 2δ-1. Cell Rep 2019; 25:1610-1621.e5. [PMID: 30404013 PMCID: PMC6231325 DOI: 10.1016/j.celrep.2018.10.033] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 08/31/2018] [Accepted: 10/05/2018] [Indexed: 12/28/2022] Open
Abstract
Voltage-gated calcium channel auxiliary α2δ subunits are important for channel trafficking and function. Here, we compare the effects of α2δ-1 and an α2δ-like protein called Cachd1 on neuronal N-type (CaV2.2) channels, which are important in neurotransmission. Previous structural studies show the α2δ-1 VWA domain interacting with the first loop in CaV1.1 domain-I via its metal ion-dependent adhesion site (MIDAS) motif and additional Cache domain interactions. Cachd1 has a disrupted MIDAS motif. However, Cachd1 increases CaV2.2 currents substantially (although less than α2δ-1) and increases CaV2.2 cell surface expression by reducing endocytosis. Although the effects of α2δ-1 are abolished by mutation of Asp122 in CaV2.2 domain-I, which mediates interaction with its VWA domain, the Cachd1 responses are unaffected. Furthermore, Cachd1 co-immunoprecipitates with CaV2.2 and inhibits co-immunoprecipitation of α2δ-1 by CaV2.2. Cachd1 also competes with α2δ-1 for effects on trafficking. Thus, Cachd1 influences both CaV2.2 trafficking and function and can inhibit responses to α2δ-1. Cachd1 enhances CaV2.2 currents and increases CaV2.2 surface expression Effects of Cachd1 are not prevented by mutation in CaV2.2 VWA interaction site The effects of α2δ-1 are prevented by the same mutation in CaV2.2 Cachd1 competes with α2δ-1 for its effects on CaV2.2
Collapse
Affiliation(s)
- Shehrazade Dahimene
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Karen M Page
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Ivan Kadurin
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Laurent Ferron
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Dominique Y Ho
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Gareth T Powell
- Department of Cell and Developmental Biology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Wendy S Pratt
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Stephen W Wilson
- Department of Cell and Developmental Biology, Division of Biosciences, University College London, London WC1E 6BT, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, UK.
| |
Collapse
|
13
|
El-Awaad E, Pryymachuk G, Fried C, Matthes J, Isensee J, Hucho T, Neiss WF, Paulsson M, Herzig S, Zaucke F, Pietsch M. Direct, gabapentin-insensitive interaction of a soluble form of the calcium channel subunit α 2δ-1 with thrombospondin-4. Sci Rep 2019; 9:16272. [PMID: 31700036 PMCID: PMC6838084 DOI: 10.1038/s41598-019-52655-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/21/2019] [Indexed: 12/31/2022] Open
Abstract
The α2δ‐1 subunit of voltage-gated calcium channels binds to gabapentin and pregabalin, mediating the analgesic action of these drugs against neuropathic pain. Extracellular matrix proteins from the thrombospondin (TSP) family have been identified as ligands of α2δ‐1 in the CNS. This interaction was found to be crucial for excitatory synaptogenesis and neuronal sensitisation which in turn can be inhibited by gabapentin, suggesting a potential role in the pathogenesis of neuropathic pain. Here, we provide information on the biochemical properties of the direct TSP/α2δ-1 interaction using an ELISA-style ligand binding assay. Our data reveal that full-length pentameric TSP-4, but neither TSP-5/COMP of the pentamer-forming subgroup B nor TSP-2 of the trimer-forming subgroup A directly interact with a soluble variant of α2δ-1 (α2δ-1S). Interestingly, this interaction is not inhibited by gabapentin on a molecular level and is not detectable on the surface of HEK293-EBNA cells over-expressing α2δ‐1 protein. These results provide biochemical evidence that supports a specific role of TSP-4 among the TSPs in mediating the binding to neuronal α2δ‐1 and suggest that gabapentin does not directly target TSP/α2δ-1 interaction to alleviate neuropathic pain.
Collapse
Affiliation(s)
- Ehab El-Awaad
- Institute II for Pharmacology, Centre of Pharmacology, Medical Faculty, University of Cologne, Gleueler Str. 24, D-50931, Cologne, Germany.,Department of Pharmacology, Faculty of Medicine, Assiut University, Assiut, 71515, Egypt
| | - Galyna Pryymachuk
- Department of Anatomy I, Medical Faculty, University of Cologne, Kerpener Str. 62, D-50937, Cologne, Germany
| | - Cora Fried
- Institute II for Pharmacology, Centre of Pharmacology, Medical Faculty, University of Cologne, Gleueler Str. 24, D-50931, Cologne, Germany
| | - Jan Matthes
- Institute II for Pharmacology, Centre of Pharmacology, Medical Faculty, University of Cologne, Gleueler Str. 24, D-50931, Cologne, Germany
| | - Jörg Isensee
- Experimental Anaesthesiology and Pain Research, Department of Anaesthesiology and Intensive Care Medicine, Medical Faculty, University of Cologne, Robert-Koch-Str. 10, D-50931, Cologne, Germany
| | - Tim Hucho
- Experimental Anaesthesiology and Pain Research, Department of Anaesthesiology and Intensive Care Medicine, Medical Faculty, University of Cologne, Robert-Koch-Str. 10, D-50931, Cologne, Germany
| | - Wolfram F Neiss
- Department of Anatomy I, Medical Faculty, University of Cologne, Kerpener Str. 62, D-50937, Cologne, Germany
| | - Mats Paulsson
- Institute for Biochemistry II, Centre for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, D-50931, Cologne, Germany.,Centre for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, D-50931, Cologne, Germany
| | - Stefan Herzig
- Institute II for Pharmacology, Centre of Pharmacology, Medical Faculty, University of Cologne, Gleueler Str. 24, D-50931, Cologne, Germany.,President of TH Köln, TH Köln (University of Applied Sciences), Claudiusstr. 1, D-50678, Cologne, Germany
| | - Frank Zaucke
- Institute for Biochemistry II, Centre for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, D-50931, Cologne, Germany.,Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Orthopedic University Hospital, Friedrichsheim gGmbH, Marienburgstr. 2, D-60528, Frankfurt/Main, Germany
| | - Markus Pietsch
- Institute II for Pharmacology, Centre of Pharmacology, Medical Faculty, University of Cologne, Gleueler Str. 24, D-50931, Cologne, Germany.
| |
Collapse
|
14
|
Calcium Signaling in Neurons and Glial Cells: Role of Cav1 channels. Neuroscience 2019; 421:95-111. [DOI: 10.1016/j.neuroscience.2019.09.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/27/2019] [Accepted: 09/30/2019] [Indexed: 11/18/2022]
|
15
|
Abstract
Voltage-gated calcium (CaV) channels are associated with β and α2δ auxiliary subunits. This review will concentrate on the function of the α2δ protein family, which has four members. The canonical role for α2δ subunits is to convey a variety of properties on the CaV1 and CaV2 channels, increasing the density of these channels in the plasma membrane and also enhancing their function. More recently, a diverse spectrum of non-canonical interactions for α2δ proteins has been proposed, some of which involve competition with calcium channels for α2δ or increase α2δ trafficking and others which mediate roles completely unrelated to their calcium channel function. The novel roles for α2δ proteins which will be discussed here include association with low-density lipoprotein receptor-related protein 1 (LRP1), thrombospondins, α-neurexins, prion proteins, large conductance (big) potassium (BK) channels, and N-methyl-d-aspartate (NMDA) receptors.
Collapse
Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| |
Collapse
|
16
|
Wang D, Ragnarsson L, Lewis RJ. T-type Calcium Channels in Health and Disease. Curr Med Chem 2018; 27:3098-3122. [PMID: 30277145 DOI: 10.2174/0929867325666181001112821] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/28/2018] [Accepted: 08/30/2018] [Indexed: 12/12/2022]
Abstract
Low Voltage-Activated (LVA) T-type calcium channels are characterized by transient current and Low Threshold Spikes (LTS) that trigger neuronal firing and oscillatory behavior. Combined with their preferential localization in dendrites and their specific "window current", T-type calcium channels are considered to be key players in signal amplification and synaptic integration. Assisted by the emerging pharmacological tools, the structural determinants of channel gating and kinetics, as well as novel physiological and pathological functions of T-type calcium channels, are being uncovered. In this review, we provide an overview of structural determinants in T-type calcium channels, their involvement in disorders and diseases, the development of novel channel modulators, as well as Structure-Activity Relationship (SAR) studies that lead to rational drug design.
Collapse
Affiliation(s)
- Dan Wang
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane Qld 4072, Australia
| | - Lotten Ragnarsson
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane Qld 4072, Australia
| | - Richard J Lewis
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane Qld 4072, Australia
| |
Collapse
|
17
|
Abstract
This review will first describe the importance of Ca2+ entry for function of excitable cells, and the subsequent discovery of voltage-activated calcium conductances in these cells. This finding was rapidly followed by the identification of multiple subtypes of calcium conductance in different tissues. These were initially termed low- and high-voltage activated currents, but were then further subdivided into L-, N-, PQ-, R- and T-type calcium currents on the basis of differing pharmacology, voltage-dependent and kinetic properties, and single channel conductance. Purification of skeletal muscle calcium channels allowed the molecular identification of the pore-forming and auxiliary α2δ, β and ϒ subunits present in these calcium channel complexes. These advances then led to the cloning of the different subunits, which permitted molecular characterisation, to match the cloned channels with physiological function. Studies with knockout and other mutant mice then allowed further investigation of physiological and pathophysiological roles of calcium channels. In terms of pharmacology, cardiovascular L-type channels are targets for the widely used antihypertensive 1,4-dihydropyridines and other calcium channel blockers, N-type channels are a drug target in pain, and α2δ-1 is the therapeutic target of the gabapentinoid drugs, used in neuropathic pain. Recent structural advances have allowed a deeper understanding of Ca2+ permeation through the channel pore and the structure of both the pore-forming and auxiliary subunits. Voltage-gated calcium channels are subject to multiple pathways of modulation by G-protein and second messenger regulation. Furthermore, their trafficking pathways, subcellular localisation and functional specificity are the subjects of active investigation.
Collapse
|
18
|
Peripheral gabapentin regulates mosquito allergy-induced itch in mice. Eur J Pharmacol 2018; 833:44-49. [PMID: 29842875 DOI: 10.1016/j.ejphar.2018.05.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 05/15/2018] [Accepted: 05/24/2018] [Indexed: 11/24/2022]
Abstract
The antipruritic activity of gabapentin, an anticonvulsant, was studied in a mouse model of allergic itch. In mice sensitized by an extract of the salivary glands of the mosquito (ESGM), an intradermal injection of ESGM elicited scratching and increased peripheral nerve firing. Oral or intradermal administration of gabapentin at the ESGM injection site inhibited ESGM-induced scratching and peripheral nerve firing. However, gabapentin did not affect histamine-induced scratching. The distributions of immunoreactivity to the voltage-dependent calcium channel α2δ-1 subunit, a site of gabapentin action, and the histamine H1 receptor differed in the mouse dorsal root ganglia. The α2δ-1 subunit was mainly found in neurons that were 15-20 µm in diameter, whereas the H1 receptor was mainly in 20-30 µm neurons. In addition, α2δ-1 subunit immunoreactivity co-localized with that of transient receptor potential vanilloid 1 (TRPV1). These results suggest that gabapentin regulates allergic itch by acting on the calcium channel α2δ-1 subunit in peripheral TRPV1-positive neurons.
Collapse
|
19
|
α-Neurexins Together with α2δ-1 Auxiliary Subunits Regulate Ca 2+ Influx through Ca v2.1 Channels. J Neurosci 2018; 38:8277-8294. [PMID: 30104341 DOI: 10.1523/jneurosci.0511-18.2018] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/03/2018] [Accepted: 07/10/2018] [Indexed: 11/21/2022] Open
Abstract
Action potential-evoked neurotransmitter release is impaired in knock-out neurons lacking synaptic cell-adhesion molecules α-neurexins (αNrxns), the extracellularly longer variants of the three vertebrate Nrxn genes. Ca2+ influx through presynaptic high-voltage gated calcium channels like the ubiquitous P/Q-type (CaV2.1) triggers release of fusion-ready vesicles at many boutons. α2δ Auxiliary subunits regulate trafficking and kinetic properties of CaV2.1 pore-forming subunits but it has remained unclear if this involves αNrxns. Using live cell imaging with Ca2+ indicators, we report here that the total presynaptic Ca2+ influx in primary hippocampal neurons of αNrxn triple knock-out mice of both sexes is reduced and involved lower CaV2.1-mediated transients. This defect is accompanied by lower vesicle release, reduced synaptic abundance of CaV2.1 pore-forming subunits, and elevated surface mobility of α2δ-1 on axons. Overexpression of Nrxn1α in αNrxn triple knock-out neurons is sufficient to restore normal presynaptic Ca2+ influx and synaptic vesicle release. Moreover, coexpression of Nrxn1α together with α2δ-1 subunits facilitates Ca2+ influx further but causes little augmentation together with a different subunit, α2δ-3, suggesting remarkable specificity. Expression of defined recombinant CaV2.1 channels in heterologous cells validates and extends the findings from neurons. Whole-cell patch-clamp recordings show that Nrxn1α in combination with α2δ-1, but not with α2δ-3, facilitates Ca2+ currents of recombinant CaV2.1 without altering channel kinetics. These results suggest that presynaptic Nrxn1α acts as a positive regulator of Ca2+ influx through CaV2.1 channels containing α2δ-1 subunits. We propose that this regulation represents an important way for neurons to adjust synaptic strength.SIGNIFICANCE STATEMENT Synaptic transmission between neurons depends on the fusion of neurotransmitter-filled vesicles with the presynaptic membrane, which subsequently activates postsynaptic receptors. Influx of calcium ions into the presynaptic terminal is the key step to trigger vesicle release and involves different subtypes of voltage-gated calcium channels. We study the regulation of calcium channels by neurexins, a family of synaptic cell-adhesion molecules that are essential for many synapse properties. Using optical measurements of calcium influx in cultured neurons and electrophysiological recordings of calcium currents from recombinant channels, we show that a major neurexin variant facilitates calcium influx through P/Q-type channels by interacting with their α2δ-1 auxiliary subunits. These results propose a novel way how neurons can modulate the strength of distinct synapses.
Collapse
|
20
|
Gong N, Park J, Luo ZD. Injury-induced maladaptation and dysregulation of calcium channel α 2 δ subunit proteins and its contribution to neuropathic pain development. Br J Pharmacol 2018; 175:2231-2243. [PMID: 28646556 PMCID: PMC5980513 DOI: 10.1111/bph.13930] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/05/2017] [Accepted: 06/12/2017] [Indexed: 01/12/2023] Open
Abstract
Voltage-gated calcium channels (VGCCs) play important roles in physiological functions including the modulation of neurotransmitter release, neuronal network activities, intracellular signalling pathways and gene expression. Some pathological conditions, including nerve injuries, can cause the dysregulation of VGCCs and their subunits. This in turn can lead to a functional maladaptation of VGCCs and their subunits, which can contribute to the development of disorders such as pain sensations. This review has summarized recent findings related to maladaptive changes in the dysregulated VGCC α2 δ1 subunit (Cav α2 δ1 ) with a focus on exploring the mechanisms underlying the contribution of Cav α2 δ1 to pain signal transduction. At least under neuropathic pain conditions, the dysregulated Cav α2 δ1 can modulate VGCC functions as well as other plasticity changes. The latter includes abnormal excitatory synaptogenesis resulting from its interactions with injury-induced extracellular matrix glycoprotein molecule thrombospondins, which is independent of the VGCC functions. Blocking Cav α2 δ1 with gabapentinoids can reverse neuropathic pain significantly with relatively mild side effects, but only in a small population of neuropathic pain patients due to reasons yet to be explored. There are emerging data suggesting that early preventive treatment with gabapentinoids can prevent aberrant excitatory synapse formation and the development of chronic pain. If these findings are confirmed clinically, this could be an attractive approach for neuropathic pain management. LINKED ARTICLES This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
Collapse
Affiliation(s)
- Nian Gong
- Department of Anesthesiology & Perioperative CareSchool of Medicine, University of California IrvineIrvineCAUSA
| | - John Park
- Department of Pharmacology, School of MedicineUniversity of California IrvineIrvineCAUSA
| | - Z David Luo
- Department of Anesthesiology & Perioperative CareSchool of Medicine, University of California IrvineIrvineCAUSA
- Department of Pharmacology, School of MedicineUniversity of California IrvineIrvineCAUSA
| |
Collapse
|
21
|
Saxena P, Hortigon‐Vinagre MP, Beyl S, Baburin I, Andranovits S, Iqbal SM, Costa A, IJzerman AP, Kügler P, Timin E, Smith GL, Hering S. Correlation between human ether-a-go-go-related gene channel inhibition and action potential prolongation. Br J Pharmacol 2017; 174:3081-3093. [PMID: 28681507 PMCID: PMC5573420 DOI: 10.1111/bph.13942] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/08/2017] [Accepted: 06/16/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Human ether-a-go-go-related gene (hERG; Kv 11.1) channel inhibition is a widely accepted predictor of cardiac arrhythmia. hERG channel inhibition alone is often insufficient to predict pro-arrhythmic drug effects. This study used a library of dofetilide derivatives to investigate the relationship between standard measures of hERG current block in an expression system and changes in action potential duration (APD) in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). The interference from accompanying block of Cav 1.2 and Nav 1.5 channels was investigated along with an in silico AP model. EXPERIMENTAL APPROACH Drug-induced changes in APD were assessed in hiPSC-CMs using voltage-sensitive dyes. The IC50 values for dofetilide and 13 derivatives on hERG current were estimated in an HEK293 expression system. The relative potency of each drug on APD was estimated by calculating the dose (D150 ) required to prolong the APD at 90% (APD90 ) repolarization by 50%. KEY RESULTS The D150 in hiPSC-CMs was linearly correlated with IC50 of hERG current. In silico simulations supported this finding. Three derivatives inhibited hERG without prolonging APD, and these compounds also inhibited Cav 1.2 and/or Nav 1.5 in a channel state-dependent manner. Adding Cav 1.2 and Nav 1.2 block to the in silico model recapitulated the direction but not the extent of the APD change. CONCLUSIONS AND IMPLICATIONS Potency of hERG current inhibition correlates linearly with an index of APD in hiPSC-CMs. The compounds that do not correlate have additional effects including concomitant block of Cav 1.2 and/or Nav 1.5 channels. In silico simulations of hiPSC-CMs APs confirm the principle of the multiple ion channel effects.
Collapse
Affiliation(s)
- P Saxena
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowGlasgowUK
| | - M P Hortigon‐Vinagre
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowGlasgowUK
- Clyde Biosciences LtdGlasgowUK
| | - S Beyl
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - I Baburin
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - S Andranovits
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - S M Iqbal
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - A Costa
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowGlasgowUK
| | - A P IJzerman
- Division of Medicinal Chemistry, Leiden Academic Centre for Drug ResearchLeiden UniversityLeidenNetherlands
| | - P Kügler
- Institute for Applied Mathematics and StatisticsUniversity of HohenheimStuttgartGermany
- Radon Institute for Computational and Applied MathematicsAustrian Academy of SciencesViennaAustria
| | - E Timin
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - G L Smith
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowGlasgowUK
- Clyde Biosciences LtdGlasgowUK
| | - S Hering
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| |
Collapse
|
22
|
Voltage gated ion channels blockade is the underlying mechanism of BIMU8 induced cardiotoxicity. Toxicol Lett 2017; 277:64-68. [DOI: 10.1016/j.toxlet.2017.05.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 05/22/2017] [Accepted: 05/23/2017] [Indexed: 11/24/2022]
|
23
|
Andranovits S, Beyl S, Hohaus A, Zangerl-Plessl EM, Timin E, Hering S. Key role of segment IS4 in Cav1.2 inactivation: link between activation and inactivation. Pflugers Arch 2017; 469:1485-1493. [PMID: 28766141 PMCID: PMC5629230 DOI: 10.1007/s00424-017-2038-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/04/2017] [Accepted: 07/13/2017] [Indexed: 11/24/2022]
Abstract
Inactivation of L-type calcium channel (Cav1.2) is an important determinant of the length of the cardiac action potential. Here, we report a key role of the voltage-sensing segment IS4 in Cav1.2 inactivation. Neutralization of IS4 charges gradually shifted the steady-state inactivation curve on the voltages axis from 5.1 ± 3.7 mV in single point mutant IS4(K1Q) to −26.7 ± 1.3 mV in quadruple mutant IS4(K1Q/R2Q/R3Q/R4Q) compared to wild-type (WT) and accelerated inactivation. The slope factor of the Boltzmann curve of inactivation was decreased from 17.4 ± 3.5 mV (IS4(K1Q)) to 6.2 ± 0.7 mV (IS4(K1Q/R2Q/R3Q/R4Q)). Neutralizations of single or multiple charges in IIS4 and IIIS4 did not significantly affect the time course of inactivation. Neutralization of individual IVS4 charges shifted the inactivation curve between 17.4 ± 1.7 mV (IVS4(R2Q)) and −4.6 ± 1.4 mV (IVS4(R4Q)) on the voltage axis and affected the slope of the inactivation curves (IVS4(R2Q): 10.2 ± 1.2 mV, IVS4(R4Q): 9.7 ± 0.7 mV and IVS4(K5Q): 8.1 ± 0.7 mV vs WT: 14.1 ± 0.8 mV). IS4(K1Q) attenuated while IS4(K1Q/R2Q/R3Q) and IS4(K1Q/R2Q/R4Q/R3Q) enhanced the development of inactivation. Shifts in the voltage dependence of inactivation curves induced by IS4 neutralizations significantly correlated with shifts of the voltage dependence of channel activation (r = 0.95, p < 0.01) indicating that IS4 movement is not only rate limiting for activation but also initiates inactivation. The paradoxical decrease of the slope factor of the steady-state inactivation and acceleration of inactivation kinetics upon charge neutralization in segment IS4 may reflect the loss of stabilizing interactions of arginines and lysine with surrounding residues.
Collapse
Affiliation(s)
- Stanislav Andranovits
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Stanislav Beyl
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria. .,Austrian Science Fund (FWF), Haus der Forschung, Sensengasse 1, 1090, Vienna, Austria.
| | - Annette Hohaus
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Eva Maria Zangerl-Plessl
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Eugen Timin
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Steffen Hering
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria. .,Austrian Science Fund (FWF), Haus der Forschung, Sensengasse 1, 1090, Vienna, Austria.
| |
Collapse
|
24
|
Tseng PY, Henderson PB, Hergarden AC, Patriarchi T, Coleman AM, Lillya MW, Montagut-Bordas C, Lee B, Hell JW, Horne MC. α-Actinin Promotes Surface Localization and Current Density of the Ca 2+ Channel Ca V1.2 by Binding to the IQ Region of the α1 Subunit. Biochemistry 2017; 56:3669-3681. [PMID: 28613835 DOI: 10.1021/acs.biochem.7b00359] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The voltage-gated L-type Ca2+ channel CaV1.2 is crucial for initiating heartbeat and control of a number of neuronal functions such as neuronal excitability and long-term potentiation. Mutations of CaV1.2 subunits result in serious health problems, including arrhythmia, autism spectrum disorders, immunodeficiency, and hypoglycemia. Thus, precise control of CaV1.2 surface expression and localization is essential. We previously reported that α-actinin associates and colocalizes with neuronal CaV1.2 channels and that shRNA-mediated depletion of α-actinin significantly reduces localization of endogenous CaV1.2 in dendritic spines in hippocampal neurons. Here we investigated the hypothesis that direct binding of α-actinin to CaV1.2 supports its surface expression. Using two-hybrid screens and pull-down assays, we identified three point mutations (K1647A, Y1649A, and I1654A) in the central, pore-forming α11.2 subunit of CaV1.2 that individually impaired α-actinin binding. Surface biotinylation and flow cytometry assays revealed that CaV1.2 channels composed of the corresponding α-actinin-binding-deficient mutants result in a 35-40% reduction in surface expression compared to that of wild-type channels. Moreover, the mutant CaV1.2 channels expressed in HEK293 cells exhibit a 60-75% decrease in current density. The larger decrease in current density as compared to surface expression imparted by these α11.2 subunit mutations hints at the possibility that α-actinin not only stabilizes surface localization of CaV1.2 but also augments its ion conducting activity.
Collapse
Affiliation(s)
- Pang-Yen Tseng
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| | - Peter B Henderson
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| | - Anne C Hergarden
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| | - Tommaso Patriarchi
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| | - Andrea M Coleman
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| | - Mark W Lillya
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| | - Carlota Montagut-Bordas
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| | - Boram Lee
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| | - Johannes W Hell
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| | - Mary C Horne
- Department of Pharmacology, School of Medicine, University of California , Davis, California 95615-8636, United States
| |
Collapse
|
25
|
Cserne Szappanos H, Viola H, Hool LC. L-type calcium channel: Clarifying the "oxygen sensing hypothesis". Int J Biochem Cell Biol 2017; 86:32-36. [PMID: 28323207 DOI: 10.1016/j.biocel.2017.03.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 03/08/2017] [Accepted: 03/14/2017] [Indexed: 11/30/2022]
Abstract
The heart is able to respond acutely to changes in oxygen tension. Since ion channels can respond rapidly to stimuli, the "ion channel oxygen sensing hypothesis" has been proposed to explain acute adaptation of cells to changes in oxygen demand. However the exact mechanism for oxygen sensing continues to be debated. Mitochondria consume the lion's share of oxygen in the heart, fuelling the production of ATP that drives excitation and contraction. Mitochondria also produce reactive oxygen species that are capable of altering the redox state of proteins. The cardiac L-type calcium channel is responsible for maintaining excitation and contraction. Recently, the reactive cysteine on the cardiac L-type calcium channel was identified. These data clarified that the channel does not respond directly to changes in oxygen tension, but rather responds to cellular redox state. This leads to acute alterations in cell signalling responsible for the development of arrhythmias and pathology.
Collapse
Affiliation(s)
- Henrietta Cserne Szappanos
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, WA, Australia
| | - Helena Viola
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, WA, Australia
| | - Livia C Hool
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, WA, Australia; Victor Chang Cardiac Research Institute, Sydney, NSW, Australia.
| |
Collapse
|
26
|
Beyl S, Hohaus A, Andranovits S, Timin E, Hering S. Upward movement of IS4 and IIIS4 is a rate-limiting stage in Ca v1.2 activation. Pflugers Arch 2016; 468:1895-1907. [PMID: 27796578 PMCID: PMC5138263 DOI: 10.1007/s00424-016-1895-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/18/2016] [Accepted: 10/12/2016] [Indexed: 01/05/2023]
Abstract
In order to specify the role of individual S4 segments in CaV1.2 gating, charged residues of segments IS4-IVS4 were replaced by glutamine and the corresponding effects on activation/deactivation of calcium channel currents were analysed. Almost all replacements of charges in IS4 and IIIS4 decreased the slope of the Boltzmann curve of channel activation (activation curve) while charge neutralisations in IIS4 and IVS4 did not significantly affect the slope. S4 mutations caused either left or rightward shifts of the activation curve, and in wild-type channels, these S4 mutations hardly affected current kinetics.In slowly gating pore (S6) mutants (G432W, A780T, G1193T or A1503G), neutralisations in S4 segments significantly accelerated current kinetics. Likewise in wild type, charge replacements in IS4 and IIIS4 of pore mutants reduced the slope of the activation curves while substitutions of charges in IIS4 and IVS4 had less or no impact. We propose a gating model where the structurally different S4 segments leave their resting positions not simultaneously. Upward movement of segments IS4 and (to a lesser extend) IIIS4 appear to be a rate-limiting stage for releasing the pore gates. These segments carry most of the effective charge for channel activation. Our study suggests that S4 segments of CaV1.2 control the closed state in domain specific manner while stabilizing the open state in a non-specific manner.
Collapse
Affiliation(s)
- Stanislav Beyl
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Annette Hohaus
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Stanislav Andranovits
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Eugen Timin
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Steffen Hering
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| |
Collapse
|
27
|
Kadurin I, Ferron L, Rothwell SW, Meyer JO, Douglas LR, Bauer CS, Lana B, Margas W, Alexopoulos O, Nieto-Rostro M, Pratt WS, Dolphin AC. Proteolytic maturation of α 2δ represents a checkpoint for activation and neuronal trafficking of latent calcium channels. eLife 2016; 5. [PMID: 27782881 PMCID: PMC5092059 DOI: 10.7554/elife.21143] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/25/2016] [Indexed: 12/23/2022] Open
Abstract
The auxiliary α2δ subunits of voltage-gated calcium channels are extracellular membrane-associated proteins, which are post-translationally cleaved into disulfide-linked polypeptides α2 and δ. We now show, using α2δ constructs containing artificial cleavage sites, that this processing is an essential step permitting voltage-dependent activation of plasma membrane N-type (CaV2.2) calcium channels. Indeed, uncleaved α2δ inhibits native calcium currents in mammalian neurons. By inducing acute cell-surface proteolytic cleavage of α2δ, voltage-dependent activation of channels is promoted, independent from the trafficking role of α2δ. Uncleaved α2δ does not support trafficking of CaV2.2 channel complexes into neuronal processes, and inhibits Ca2+ entry into synaptic boutons, and we can reverse this by controlled intracellular proteolytic cleavage. We propose a model whereby uncleaved α2δ subunits maintain immature calcium channels in an inhibited state. Proteolytic processing of α2δ then permits voltage-dependent activation of the channels, acting as a checkpoint allowing trafficking only of mature calcium channel complexes into neuronal processes. DOI:http://dx.doi.org/10.7554/eLife.21143.001
Collapse
Affiliation(s)
- Ivan Kadurin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Laurent Ferron
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Simon W Rothwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - James O Meyer
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Leon R Douglas
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Claudia S Bauer
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Beatrice Lana
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Wojciech Margas
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Orpheas Alexopoulos
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Manuela Nieto-Rostro
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Wendy S Pratt
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| |
Collapse
|
28
|
Dolphin AC. Voltage-gated calcium channels and their auxiliary subunits: physiology and pathophysiology and pharmacology. J Physiol 2016; 594:5369-90. [PMID: 27273705 PMCID: PMC5043047 DOI: 10.1113/jp272262] [Citation(s) in RCA: 208] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/09/2016] [Indexed: 12/22/2022] Open
Abstract
Voltage‐gated calcium channels are essential players in many physiological processes in excitable cells. There are three main subdivisions of calcium channel, defined by the pore‐forming α1 subunit, the CaV1, CaV2 and CaV3 channels. For all the subtypes of voltage‐gated calcium channel, their gating properties are key for the precise control of neurotransmitter release, muscle contraction and cell excitability, among many other processes. For the CaV1 and CaV2 channels, their ability to reach their required destinations in the cell membrane, their activation and the fine tuning of their biophysical properties are all dramatically influenced by the auxiliary subunits that associate with them. Furthermore, there are many diseases, both genetic and acquired, involving voltage‐gated calcium channels. This review will provide a general introduction and then concentrate particularly on the role of auxiliary α2δ subunits in both physiological and pathological processes involving calcium channels, and as a therapeutic target.
![]()
Collapse
Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
| |
Collapse
|
29
|
Park J, Yu YP, Zhou CY, Li KW, Wang D, Chang E, Kim DS, Vo B, Zhang X, Gong N, Sharp K, Steward O, Vitko I, Perez-Reyes E, Eroglu C, Barres B, Zaucke F, Feng G, Luo ZD. Central Mechanisms Mediating Thrombospondin-4-induced Pain States. J Biol Chem 2016; 291:13335-48. [PMID: 27129212 DOI: 10.1074/jbc.m116.723478] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Indexed: 12/30/2022] Open
Abstract
Peripheral nerve injury induces increased expression of thrombospondin-4 (TSP4) in spinal cord and dorsal root ganglia that contributes to neuropathic pain states through unknown mechanisms. Here, we test the hypothesis that TSP4 activates its receptor, the voltage-gated calcium channel Cavα2δ1 subunit (Cavα2δ1), on sensory afferent terminals in dorsal spinal cord to promote excitatory synaptogenesis and central sensitization that contribute to neuropathic pain states. We show that there is a direct molecular interaction between TSP4 and Cavα2δ1 in the spinal cord in vivo and that TSP4/Cavα2δ1-dependent processes lead to increased behavioral sensitivities to stimuli. In dorsal spinal cord, TSP4/Cavα2δ1-dependent processes lead to increased frequency of miniature and amplitude of evoked excitatory post-synaptic currents in second-order neurons as well as increased VGlut2- and PSD95-positive puncta, indicative of increased excitatory synapses. Blockade of TSP4/Cavα2δ1-dependent processes with Cavα2δ1 ligand gabapentin or genetic Cavα2δ1 knockdown blocks TSP4 induced nociception and its pathological correlates. Conversely, TSP4 antibodies or genetic ablation blocks nociception and changes in synaptic transmission in mice overexpressing Cavα2δ1 Importantly, TSP4/Cavα2δ1-dependent processes also lead to similar behavioral and pathological changes in a neuropathic pain model of peripheral nerve injury. Thus, a TSP4/Cavα2δ1-dependent pathway activated by TSP4 or peripheral nerve injury promotes exaggerated presynaptic excitatory input and evoked sensory neuron hyperexcitability and excitatory synaptogenesis, which together lead to central sensitization and pain state development.
Collapse
Affiliation(s)
- John Park
- From the Department of Pharmacology and
| | | | | | - Kang-Wu Li
- Department of Anesthesiology and Perioperative Care, University of California, Irvine, California 92697
| | - Dongqing Wang
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Eric Chang
- Department of Anesthesiology and Perioperative Care, University of California, Irvine, California 92697
| | - Doo-Sik Kim
- Department of Anesthesiology and Perioperative Care, University of California, Irvine, California 92697
| | - Benjamin Vo
- Department of Anesthesiology and Perioperative Care, University of California, Irvine, California 92697
| | - Xia Zhang
- Department of Anesthesiology and Perioperative Care, University of California, Irvine, California 92697
| | - Nian Gong
- Department of Anesthesiology and Perioperative Care, University of California, Irvine, California 92697
| | - Kelli Sharp
- Reeve-Irvine Research Center, University of California, Irvine, School of Medicine, Irvine, California 92697
| | - Oswald Steward
- Reeve-Irvine Research Center, University of California, Irvine, School of Medicine, Irvine, California 92697
| | - Iuliia Vitko
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908
| | - Edward Perez-Reyes
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908
| | - Cagla Eroglu
- Cell Biology, Duke University Medical Center, Durham, North Carolina 27710
| | - Ben Barres
- Department of Neurobiology, Stanford University, Stanford, California 94305, and
| | - Frank Zaucke
- Center for Biochemistry and Cologne Center for Musculoskeletal Biomechanics, Medical Faculty, University of Cologne, D50931 Cologne, Germany
| | - Guoping Feng
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Z David Luo
- From the Department of Pharmacology and Department of Anesthesiology and Perioperative Care, University of California, Irvine, California 92697, Reeve-Irvine Research Center, University of California, Irvine, School of Medicine, Irvine, California 92697,
| |
Collapse
|
30
|
Abstract
A central theme in the quest to unravel the genetic basis of epilepsy has been the effort to elucidate the roles played by inherited defects in ion channels. The ubiquitous expression of voltage-gated calcium channels (VGCCs) throughout the central nervous system (CNS), along with their involvement in fundamental processes, such as neuronal excitability and synaptic transmission, has made them attractive candidates. Recent insights provided by the identification of mutations in the P/Q-type calcium channel in humans and rodents with epilepsy and the finding of thalamic T-type calcium channel dysfunction in the absence of seizures have raised expectations of a causal role of calcium channels in the polygenic inheritance of idiopathic epilepsy. In this review, we consider how genetic variation in neuronal VGCCs may influence the development of epilepsy.
Collapse
Affiliation(s)
- Sanjeev Rajakulendran
- UCL-Institute of Neurology, MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
| | - Michael G Hanna
- UCL-Institute of Neurology, MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
| |
Collapse
|
31
|
Zamponi GW, Striessnig J, Koschak A, Dolphin AC. The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential. Pharmacol Rev 2015; 67:821-70. [PMID: 26362469 PMCID: PMC4630564 DOI: 10.1124/pr.114.009654] [Citation(s) in RCA: 719] [Impact Index Per Article: 79.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.
Collapse
Affiliation(s)
- Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Joerg Striessnig
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Alexandra Koschak
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Annette C Dolphin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| |
Collapse
|
32
|
Mendus D, Rankin-Gee EK, Mustapha M, Porter BE. Increased sensitivity to kindling in mice lacking TSP1. Neuroscience 2015; 305:302-8. [PMID: 26241338 PMCID: PMC6699182 DOI: 10.1016/j.neuroscience.2015.07.075] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 07/17/2015] [Accepted: 07/28/2015] [Indexed: 10/23/2022]
Abstract
The development of a hyperexcitable neuronal network is thought to be a critical event in epilepsy. Thrombospondins (TSPs) regulate synaptogenesis by binding the neuronal α2δ subunit of the voltage-gated calcium channel. TSPs regulate synapse formation during development and in the mature brain following injury. It is unclear if TSPs are involved in hyperexcitability that contributes to the development of epilepsy. Here we explore the development of epilepsy using a pentylenetetrazole (PTZ) kindling model in mice lacking TSP1 and TSP2. Unexpectedly, we found increased sensitivity to PTZ kindling in mice lacking TSP1, while mice lacking TSP2 kindled similar to wild-type. We found that the increased seizure susceptibility in the TSP1 knockout (KO) mice was not due to a compensatory increase in TSP2 mRNA as TSP1/2 KO mice were sensitive to PTZ, similar to the TSP1 KO mice. Furthermore, there were similar levels of TGF-B signal activation during kindling in the TSP1 KO mice compared to wild-type. We observed decreased expression of voltage-dependent calcium channel subunit CACNA2D1 mRNA in TSP1, TSP2, and TSP1/2 KO mice. Decreased CACNA2D2 mRNA was only detected in mice that lacked TSP1 and α2δ-1/2 protein levels in the cortex were lower in the TSP 1/2 KO mice. CACNA2D2 knockout mice have spontaneous seizures and increased PTZ seizure susceptibility. Here we report similar findings, TSP1, and TSP1/2 KO mice have low levels of CACNA2D2 mRNA expression and α2δ-1/2 receptor level in the cortex, and are more susceptible to seizures. CACNA2D2 mutations in mice and humans can cause epilepsy. Our data suggest TSP1 in particular may control CACNA2D2 levels and could be a modifier of seizure susceptibility.
Collapse
Affiliation(s)
- D Mendus
- The Department of Neurology, School of Medicine, Stanford University, Stanford, CA 94305, USA; The Department of Otolaryngology - Head and Neck Surgery, School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - E K Rankin-Gee
- The Department of Neurology, School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - M Mustapha
- The Department of Otolaryngology - Head and Neck Surgery, School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - B E Porter
- The Department of Neurology, School of Medicine, Stanford University, Stanford, CA 94305, USA.
| |
Collapse
|
33
|
Heyes S, Pratt WS, Rees E, Dahimene S, Ferron L, Owen MJ, Dolphin AC. Genetic disruption of voltage-gated calcium channels in psychiatric and neurological disorders. Prog Neurobiol 2015; 134:36-54. [PMID: 26386135 PMCID: PMC4658333 DOI: 10.1016/j.pneurobio.2015.09.002] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 09/08/2015] [Accepted: 09/08/2015] [Indexed: 12/15/2022]
Abstract
Voltage-gated calcium channel classification—genes and proteins. Genetic analysis of neuropsychiatric syndromes. Calcium channel genes identified from GWA studies of psychiatric disorders. Rare mutations in calcium channel genes in psychiatric disorders. Pathophysiological sequelae of CACNA1C mutations and polymorphisms. Monogenic disorders resulting from harmful mutations in other voltage-gated calcium channel genes. Changes in calcium channel gene expression in disease. Involvement of voltage-gated calcium channels in early brain development.
This review summarises genetic studies in which calcium channel genes have been connected to the spectrum of neuropsychiatric syndromes, from bipolar disorder and schizophrenia to autism spectrum disorders and intellectual impairment. Among many other genes, striking numbers of the calcium channel gene superfamily have been implicated in the aetiology of these diseases by various DNA analysis techniques. We will discuss how these relate to the known monogenic disorders associated with point mutations in calcium channels. We will then examine the functional evidence for a causative link between these mutations or single nucleotide polymorphisms and the disease processes. A major challenge for the future will be to translate the expanding psychiatric genetic findings into altered physiological function, involvement in the wider pathology of the diseases, and what potential that provides for personalised and stratified treatment options for patients.
Collapse
Affiliation(s)
- Samuel Heyes
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Wendy S Pratt
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Elliott Rees
- Medical Research Council Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Shehrazade Dahimene
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Laurent Ferron
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Michael J Owen
- Medical Research Council Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK.
| |
Collapse
|
34
|
Campiglio M, Flucher BE. The role of auxiliary subunits for the functional diversity of voltage-gated calcium channels. J Cell Physiol 2015; 230:2019-31. [PMID: 25820299 PMCID: PMC4672716 DOI: 10.1002/jcp.24998] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 03/23/2015] [Indexed: 11/18/2022]
Abstract
Voltage-gated calcium channels (VGCCs) represent the sole mechanism to convert membrane depolarization into cellular functions like secretion, contraction, or gene regulation. VGCCs consist of a pore-forming α1 subunit and several auxiliary channel subunits. These subunits come in multiple isoforms and splice-variants giving rise to a stunning molecular diversity of possible subunit combinations. It is generally believed that specific auxiliary subunits differentially regulate the channels and thereby contribute to the great functional diversity of VGCCs. If auxiliary subunits can associate and dissociate from pre-existing channel complexes, this would allow dynamic regulation of channel properties. However, most auxiliary subunits modulate current properties very similarly, and proof that any cellular calcium channel function is indeed modulated by the physiological exchange of auxiliary subunits is still lacking. In this review we summarize available information supporting a differential modulation of calcium channel functions by exchange of auxiliary subunits, as well as experimental evidence in support of alternative functions of the auxiliary subunits. At the heart of the discussion is the concept that, in their native environment, VGCCs function in the context of macromolecular signaling complexes and that the auxiliary subunits help to orchestrate the diverse protein–protein interactions found in these calcium channel signalosomes. Thus, in addition to a putative differential modulation of current properties, differential subcellular targeting properties and differential protein–protein interactions of the auxiliary subunits may explain the need for their vast molecular diversity. J. Cell. Physiol. 999: 00–00, 2015. © 2015 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc. J. Cell. Physiol. 230: 2019–2031, 2015. © 2015 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Marta Campiglio
- Division of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| | - Bernhard E Flucher
- Division of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| |
Collapse
|
35
|
Tian X, Gala U, Zhang Y, Shang W, Nagarkar Jaiswal S, di Ronza A, Jaiswal M, Yamamoto S, Sandoval H, Duraine L, Sardiello M, Sillitoe RV, Venkatachalam K, Fan H, Bellen HJ, Tong C. A voltage-gated calcium channel regulates lysosomal fusion with endosomes and autophagosomes and is required for neuronal homeostasis. PLoS Biol 2015; 13:e1002103. [PMID: 25811491 PMCID: PMC4374850 DOI: 10.1371/journal.pbio.1002103] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Accepted: 02/11/2015] [Indexed: 01/03/2023] Open
Abstract
Autophagy helps deliver sequestered intracellular cargo to lysosomes for proteolytic degradation and thereby maintains cellular homeostasis by preventing accumulation of toxic substances in cells. In a forward mosaic screen in Drosophila designed to identify genes required for neuronal function and maintenance, we identified multiple cacophony (cac) mutant alleles. They exhibit an age-dependent accumulation of autophagic vacuoles (AVs) in photoreceptor terminals and eventually a degeneration of the terminals and surrounding glia. cac encodes an α1 subunit of a Drosophila voltage-gated calcium channel (VGCC) that is required for synaptic vesicle fusion with the plasma membrane and neurotransmitter release. Here, we show that cac mutant photoreceptor terminals accumulate AV-lysosomal fusion intermediates, suggesting that Cac is necessary for the fusion of AVs with lysosomes, a poorly defined process. Loss of another subunit of the VGCC, α2δ or straightjacket (stj), causes phenotypes very similar to those caused by the loss of cac, indicating that the VGCC is required for AV-lysosomal fusion. The role of VGCC in AV-lysosomal fusion is evolutionarily conserved, as the loss of the mouse homologues, Cacna1a and Cacna2d2, also leads to autophagic defects in mice. Moreover, we find that CACNA1A is localized to the lysosomes and that loss of lysosomal Cacna1a in cerebellar cultured neurons leads to a failure of lysosomes to fuse with endosomes and autophagosomes. Finally, we show that the lysosomal CACNA1A but not the plasma-membrane resident CACNA1A is required for lysosomal fusion. In summary, we present a model in which the VGCC plays a role in autophagy by regulating the fusion of AVs with lysosomes through its calcium channel activity and hence functions in maintaining neuronal homeostasis. A voltage-gated calcium channel required for neurotransmitter release also regulates the fusion of neuronal lysosomes with endosomes and autophagosomes, thereby helping to maintain cellular homeostasis. Autophagy is a cellular process used by cells to prevent the accumulation of toxic substances. It delivers misfolded proteins and damaged organelles by fusing autophagosomes—organelles formed by a double membrane that surrounds the “debris” to be eliminated—with lysosomes. How this fusion process is regulated during autophagy, however, remains to be established. Here, we analyze this process in flies and mice, and find that loss of different subunits of a specific type of Voltage Gated Calcium Channel (VGCC) leads to defects in lysosomal fusion with autophagosomes in neurons. It was already known that VGCCs control calcium entry at synaptic terminals to promote the fusion of synaptic vesicles with the plasma membrane, and that mutations in the subunits of VGCCs in humans cause neurological diseases. Our data indicate that defects in autophagy and lysosomal fusion are independent of defects in synaptic vesicle fusion and neurotransmitter release, and we show that a specific VGCC is present on lysosomal membranes where it is required for lysosomal fusion with endosomes and autophagosomes. These observations suggest that the fusion events required in autophagy rely on mechanisms similar to those that trigger the fusion of synaptic vesicles with the presynaptic membrane.
Collapse
Affiliation(s)
- Xuejun Tian
- Life Sciences Institute and Innovation Center for Cell Biology, Zhejiang University, Hangzhou, China
| | - Upasana Gala
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Yongping Zhang
- Life Sciences Institute and Innovation Center for Cell Biology, Zhejiang University, Hangzhou, China
| | - Weina Shang
- Life Sciences Institute and Innovation Center for Cell Biology, Zhejiang University, Hangzhou, China
| | - Sonal Nagarkar Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Alberto di Ronza
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
| | - Manish Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Shinya Yamamoto
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
| | - Hector Sandoval
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
| | - Lita Duraine
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Marco Sardiello
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
| | - Roy V. Sillitoe
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
- Department of Pathology and Immunology, Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kartik Venkatachalam
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Integrative Biology and Pharmacology, University of Texas School of Medicine, Houston, Texas, United States of America
| | - Hengyu Fan
- Life Sciences Institute and Innovation Center for Cell Biology, Zhejiang University, Hangzhou, China
| | - Hugo J. Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail: (CT), (HJB)
| | - Chao Tong
- Life Sciences Institute and Innovation Center for Cell Biology, Zhejiang University, Hangzhou, China
- * E-mail: (CT), (HJB)
| |
Collapse
|
36
|
Voltage-gated calcium channels: Determinants of channel function and modulation by inorganic cations. Prog Neurobiol 2015; 129:1-36. [PMID: 25817891 DOI: 10.1016/j.pneurobio.2014.12.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 12/15/2014] [Accepted: 12/27/2014] [Indexed: 11/20/2022]
Abstract
Voltage-gated calcium channels (VGCCs) represent a key link between electrical signals and non-electrical processes, such as contraction, secretion and transcription. Evolved to achieve high rates of Ca(2+)-selective flux, they possess an elaborate mechanism for selection of Ca(2+) over foreign ions. It has been convincingly linked to competitive binding in the pore, but the fundamental question of how this is reconcilable with high rates of Ca(2+) transfer remains unanswered. By virtue of their similarity to Ca(2+), polyvalent cations can interfere with the function of VGCCs and have proven instrumental in probing the mechanisms underlying selective permeation. Recent emergence of crystallographic data on a set of Ca(2+)-selective model channels provides a structural framework for permeation in VGCCs, and warrants a reconsideration of their diverse modulation by polyvalent cations, which can be roughly separated into three general mechanisms: (I) long-range interactions with charged regions on the surface, affecting the local potential sensed by the channel or influencing voltage-sensor movement by repulsive forces (electrostatic effects), (II) short-range interactions with sites in the ion-conducting pathway, leading to physical obstruction of the channel (pore block), and in some cases (III) short-range interactions with extracellular binding sites, leading to non-electrostatic modifications of channel gating (allosteric effects). These effects, together with the underlying molecular modifications, provide valuable insights into the function of VGCCs, and have important physiological and pathophysiological implications. Allosteric suppression of some of the pore-forming Cavα1-subunits (Cav2.3, Cav3.2) by Zn(2+) and Cu(2+) may play a major role for the regulation of excitability by endogenous transition metal ions. The fact that these ions can often traverse VGCCs can contribute to the detrimental intracellular accumulation of metal ions following excessive release of endogenous Cu(2+) and Zn(2+) or exposure to non-physiological toxic metal ions.
Collapse
|
37
|
Neely A, Hidalgo P. Structure-function of proteins interacting with the α1 pore-forming subunit of high-voltage-activated calcium channels. Front Physiol 2014; 5:209. [PMID: 24917826 PMCID: PMC4042065 DOI: 10.3389/fphys.2014.00209] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 05/15/2014] [Indexed: 11/13/2022] Open
Abstract
Openings of high-voltage-activated (HVA) calcium channels lead to a transient increase in calcium concentration that in turn activate a plethora of cellular functions, including muscle contraction, secretion and gene transcription. To coordinate all these responses calcium channels form supramolecular assemblies containing effectors and regulatory proteins that couple calcium influx to the downstream signal cascades and to feedback elements. According to the original biochemical characterization of skeletal muscle Dihydropyridine receptors, HVA calcium channels are multi-subunit protein complexes consisting of a pore-forming subunit (α1) associated with four additional polypeptide chains β, α2, δ, and γ, often referred to as accessory subunits. Twenty-five years after the first purification of a high-voltage calcium channel, the concept of a flexible stoichiometry to expand the repertoire of mechanisms that regulate calcium channel influx has emerged. Several other proteins have been identified that associate directly with the α1-subunit, including calmodulin and multiple members of the small and large GTPase family. Some of these proteins only interact with a subset of α1-subunits and during specific stages of biogenesis. More strikingly, most of the α1-subunit interacting proteins, such as the β-subunit and small GTPases, regulate both gating and trafficking through a variety of mechanisms. Modulation of channel activity covers almost all biophysical properties of the channel. Likewise, regulation of the number of channels in the plasma membrane is performed by altering the release of the α1-subunit from the endoplasmic reticulum, by reducing its degradation or enhancing its recycling back to the cell surface. In this review, we discuss the structural basis, interplay and functional role of selected proteins that interact with the central pore-forming subunit of HVA calcium channels.
Collapse
Affiliation(s)
- Alan Neely
- Centro Interdisciplinario de Neurociencia de Valparaíso and Facultad de Ciencias, Universidad de Valparaíso Valparaíso, Chile
| | - Patricia Hidalgo
- Forschungszentrum Jülich, Institute of Complex Systems 4, Zelluläre Biophysik Jülich, Germany
| |
Collapse
|
38
|
Functional exofacially tagged N-type calcium channels elucidate the interaction with auxiliary α2δ-1 subunits. Proc Natl Acad Sci U S A 2014; 111:8979-84. [PMID: 24889613 DOI: 10.1073/pnas.1403731111] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CaV1 and CaV2 voltage-gated calcium channels are associated with β and α2δ accessory subunits. However, examination of cell surface-associated CaV2 channels has been hampered by the lack of antibodies to cell surface-accessible epitopes and of functional exofacially tagged CaV2 channels. Here we report the development of fully functional CaV2.2 constructs containing inserted surface-accessible exofacial tags, which allow visualization of only those channels at the plasma membrane, in both a neuronal cell line and neurons. We first examined the effect of the auxiliary subunits. Although α2δ subunits copurify with CaV2 channels, it has recently been suggested that this interaction is easily disrupted and nonquantitative. We have now tested whether α2δ subunits are associated with these channels at the cell surface. We found that, whereas α2δ-1 is readily observed at the plasma membrane when expressed alone, it appears absent when coexpressed with CaV2.2/β1b, despite our finding that α2δ-1 increases plasma-membrane CaV2.2 expression. However, this was due to occlusion of the antigenic epitope by association with CaV2.2, as revealed by antigen retrieval; thus, our data provide evidence for a tight interaction between α2δ-1 and the α1 subunit at the plasma membrane. We further show that, although CaV2.2 cell-surface expression is reduced by gabapentin in the presence of wild-type α2δ-1 (but not a gabapentin-insensitive α2δ-1 mutant), the interaction between CaV2.2 and α2δ-1 is not disrupted by gabapentin. Altogether, these results demonstrate that CaV2.2 and α2δ-1 are intimately associated at the plasma membrane and allow us to infer a region of interaction.
Collapse
|
39
|
Hofmann F, Flockerzi V, Kahl S, Wegener JW. L-type CaV1.2 calcium channels: from in vitro findings to in vivo function. Physiol Rev 2014; 94:303-26. [PMID: 24382889 DOI: 10.1152/physrev.00016.2013] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The L-type Cav1.2 calcium channel is present throughout the animal kingdom and is essential for some aspects of CNS function, cardiac and smooth muscle contractility, neuroendocrine regulation, and multiple other processes. The L-type CaV1.2 channel is built by up to four subunits; all subunits exist in various splice variants that potentially affect the biophysical and biological functions of the channel. Many of the CaV1.2 channel properties have been analyzed in heterologous expression systems including regulation of the L-type CaV1.2 channel by Ca(2+) itself and protein kinases. However, targeted mutations of the calcium channel genes confirmed only some of these in vitro findings. Substitution of the respective serines by alanine showed that β-adrenergic upregulation of the cardiac CaV1.2 channel did not depend on the phosphorylation of the in vitro specified amino acids. Moreover, well-established in vitro phosphorylation sites of the CaVβ2 subunit of the cardiac L-type CaV1.2 channel were found to be irrelevant for the in vivo regulation of the channel. However, the molecular basis of some kinetic properties, such as Ca(2+)-dependent inactivation and facilitation, has been approved by in vivo mutagenesis of the CaV1.2α1 gene. This article summarizes recent findings on the in vivo relevance of well-established in vitro results.
Collapse
|
40
|
Li KW, Yu YP, Zhou C, Kim DS, Lin B, Sharp K, Steward O, Luo ZD. Calcium channel α2δ1 proteins mediate trigeminal neuropathic pain states associated with aberrant excitatory synaptogenesis. J Biol Chem 2014; 289:7025-7037. [PMID: 24459143 DOI: 10.1074/jbc.m114.548990] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
To investigate a potential mechanism underlying trigeminal nerve injury-induced orofacial hypersensitivity, we used a rat model of chronic constriction injury to the infraorbital nerve (CCI-ION) to study whether CCI-ION caused calcium channel α2δ1 (Cavα2δ1) protein dysregulation in trigeminal ganglia and associated spinal subnucleus caudalis and C1/C2 cervical dorsal spinal cord (Vc/C2). Furthermore, we studied whether this neuroplasticity contributed to spinal neuron sensitization and neuropathic pain states. CCI-ION caused orofacial hypersensitivity that correlated with Cavα2δ1 up-regulation in trigeminal ganglion neurons and Vc/C2. Blocking Cavα2δ1 with gabapentin, a ligand for the Cavα2δ1 proteins, or Cavα2δ1 antisense oligodeoxynucleotides led to a reversal of orofacial hypersensitivity, supporting an important role of Cavα2δ1 in orofacial pain processing. Importantly, increased Cavα2δ1 in Vc/C2 superficial dorsal horn was associated with increased excitatory synaptogenesis and increased frequency, but not the amplitude, of miniature excitatory postsynaptic currents in dorsal horn neurons that could be blocked by gabapentin. Thus, CCI-ION-induced Cavα2δ1 up-regulation may contribute to orofacial neuropathic pain states through abnormal excitatory synapse formation and enhanced presynaptic excitatory neurotransmitter release in Vc/C2.
Collapse
Affiliation(s)
- Kang-Wu Li
- Department of Anesthesiology and Perioperative Care, University of California School of Medicine, Irvine, California 92697
| | - Yanhui Peter Yu
- Department of Pharmacology, University of California School of Medicine, Irvine, California 92697
| | - Chunyi Zhou
- Department of Pharmacology, University of California School of Medicine, Irvine, California 92697
| | - Doo-Sik Kim
- Department of Anesthesiology and Perioperative Care, University of California School of Medicine, Irvine, California 92697
| | - Bin Lin
- Department of Anesthesiology and Perioperative Care, University of California School of Medicine, Irvine, California 92697
| | - Kelli Sharp
- Reeve-Irvine Research Center, University of California School of Medicine, Irvine, California 92697
| | - Oswald Steward
- Reeve-Irvine Research Center, University of California School of Medicine, Irvine, California 92697
| | - Z David Luo
- Department of Anesthesiology and Perioperative Care, University of California School of Medicine, Irvine, California 92697; Department of Pharmacology, University of California School of Medicine, Irvine, California 92697; Reeve-Irvine Research Center, University of California School of Medicine, Irvine, California 92697.
| |
Collapse
|
41
|
De Sevilla Müller LP, Liu J, Solomon A, Rodriguez A, Brecha NC. Expression of voltage-gated calcium channel α(2)δ(4) subunits in the mouse and rat retina. J Comp Neurol 2014; 521:2486-501. [PMID: 23296739 DOI: 10.1002/cne.23294] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 12/12/2012] [Accepted: 12/27/2012] [Indexed: 01/18/2023]
Abstract
High-voltage activated Ca channels participate in multiple cellular functions, including transmitter release, excitation, and gene transcription. Ca channels are heteromeric proteins consisting of a pore-forming α(1) subunit and auxiliary α(2)δ and β subunits. Although there are reports of α(2)δ(4) subunit mRNA in the mouse retina and localization of the α(2)δ(4) subunit immunoreactivity to salamander photoreceptor terminals, there is a limited overall understanding of its expression and localization in the retina. α(2)δ(4) subunit expression and distribution in the mouse and rat retina were evaluated by using reverse transcriptase polymerase chain reaction, western blot, and immunohistochemistry with specific primers and a well-characterized antibody to the α(2)δ(4) subunit. α(2)δ(4) subunit mRNA and protein are present in mouse and rat retina, brain, and liver homogenates. Immunostaining for the α(2)δ(4) subunit is mainly localized to Müller cell processes and endfeet, photoreceptor terminals, and photoreceptor outer segments. This subunit is also expressed in a few displaced ganglion cells and bipolar cell dendrites. These findings suggest that the α(2)δ(4) subunit participates in the modulation of L-type Ca(2+) current regulating neurotransmitter release from photoreceptor terminals and Ca(2+)-dependent signaling pathways in bipolar and Müller cells.
Collapse
Affiliation(s)
- Luis Pérez De Sevilla Müller
- Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, California 90095, USA.
| | | | | | | | | |
Collapse
|
42
|
Lana B, Schlick B, Martin S, Pratt WS, Page KM, Goncalves L, Rahman W, Dickenson AH, Bauer CS, Dolphin AC. Differential upregulation in DRG neurons of an α2δ-1 splice variant with a lower affinity for gabapentin after peripheral sensory nerve injury. Pain 2013; 155:522-533. [PMID: 24315988 PMCID: PMC3988960 DOI: 10.1016/j.pain.2013.12.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/14/2013] [Accepted: 12/02/2013] [Indexed: 11/17/2022]
Abstract
The α2δ-1 protein is an auxiliary subunit of voltage-gated calcium channels, critical for neurotransmitter release. It is upregulated in dorsal root ganglion (DRG) neurons following sensory nerve injury, and is also the therapeutic target of the gabapentinoid drugs, which are efficacious in both experimental and human neuropathic pain conditions. α2δ-1 has 3 spliced regions: A, B, and C. A and C are cassette exons, whereas B is introduced via an alternative 3' splice acceptor site. Here we have examined the presence of α2δ-1 splice variants in DRG neurons, and have found that although the main α2δ-1 splice variant in DRG is the same as that in brain (α2δ-1 ΔA+B+C), there is also another α2δ-1 splice variant (ΔA+BΔC), which is expressed in DRG neurons and is differentially upregulated compared to the main DRG splice variant α2δ-1 ΔA+B+C following spinal nerve ligation. Furthermore, this differential upregulation occurs preferentially in a small nonmyelinated DRG neuron fraction, obtained by density gradient separation. The α2δ-1 ΔA+BΔC splice variant supports CaV2 calcium currents with unaltered properties compared to α2δ-1 ΔA+B+C, but shows a significantly reduced affinity for gabapentin. This variant could therefore play a role in determining the efficacy of gabapentin in neuropathic pain.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Annette C. Dolphin
- Corresponding author. Address: Department of Neuroscience, Physiology and Pharmacology, Andrew Huxley Building, University College London, Gower St., London WC1E6BT, UK.
| |
Collapse
|
43
|
HARTZELL HCRISS, DUCHATELLE-GOURDON ISABELLE. Structure and Neural Modulation of Cardiac Calcium Channels. J Cardiovasc Electrophysiol 2013. [DOI: 10.1111/j.1540-8167.1992.tb01937.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
44
|
The α2δ subunits of voltage-gated calcium channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013. [DOI: 10.1016/j.bbamem.2012.11.019] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
45
|
Ca2+ channel and Na+/Ca2+ exchange localization in cardiac myocytes. J Mol Cell Cardiol 2013; 58:22-31. [DOI: 10.1016/j.yjmcc.2012.11.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 11/20/2012] [Accepted: 11/28/2012] [Indexed: 01/01/2023]
|
46
|
How insensitive … How a mutation in the SCN5A voltage sensor leads to clinical arrhythmia. Heart Rhythm 2012; 9:1689-90. [DOI: 10.1016/j.hrthm.2012.07.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Indexed: 11/17/2022]
|
47
|
Neutralisation of a single voltage sensor affects gating determinants in all four pore-forming S6 segments of Ca(V)1.2: a cooperative gating model. Pflugers Arch 2012; 464:391-401. [PMID: 22941337 DOI: 10.1007/s00424-012-1144-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 08/14/2012] [Accepted: 08/16/2012] [Indexed: 10/27/2022]
Abstract
Voltage sensors trigger the closed-open transitions in the pore of voltage-gated ion channels. To probe the transmission of voltage sensor signalling to the channel pore of Ca(V)1.2, we investigated how elimination of positive charges in the S4 segments (charged residues were replaced by neutral glutamine) modulates gating perturbations induced by mutations in pore-lining S6 segments. Neutralisation of all positively charged residues in IIS4 produced a functional channel (IIS4(N)), while replacement of the charged residues in IS4, IIIS4 and IVS4 segments resulted in nonfunctional channels. The IIS4(N) channel displayed activation kinetics similar to wild type. Mutations in a highly conserved structure motif on S6 segments ("GAGA ring": G432W in IS6, A780T in IIS6, G1193T in IIIS6 and A1503G in IVS6) induce strong left-shifted activation curves and decelerated channel deactivation kinetics. When IIS4(N) was combined with these mutations, the activation curves were shifted back towards wild type and current kinetics were accelerated. In contrast, 12 other mutations adjacent to the GAGA ring in IS6-IVS6, which also affect activation gating, were not rescued by IIS4(N). Thus, the rescue of gating distortions in segments IS6-IVS6 by IIS4(N) is highly position-specific. Thermodynamic cycle analysis supports the hypothesis that IIS4 is energetically coupled with the distantly located GAGA residues. We speculate that conformational changes caused by neutralisation of IIS4 are not restricted to domain II (IIS6) but are transmitted to gating structures in domains I, III and IV via the GAGA ring.
Collapse
|
48
|
Kadurin I, Alvarez-Laviada A, Ng SFJ, Walker-Gray R, D'Arco M, Fadel MG, Pratt WS, Dolphin AC. Calcium currents are enhanced by α2δ-1 lacking its membrane anchor. J Biol Chem 2012; 287:33554-66. [PMID: 22869375 PMCID: PMC3460456 DOI: 10.1074/jbc.m112.378554] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The accessory α(2)δ subunits of voltage-gated calcium channels are membrane-anchored proteins, which are highly glycosylated, possess multiple disulfide bonds, and are post-translationally cleaved into α(2) and δ. All α(2)δ subunits have a C-terminal hydrophobic, potentially trans-membrane domain and were described as type I transmembrane proteins, but we found evidence that they can be glycosylphosphatidylinositol-anchored. To probe further the function of membrane anchoring in α(2)δ subunits, we have now examined the properties of α(2)δ-1 constructs truncated at their putative glycosylphosphatidylinositol anchor site, located before the C-terminal hydrophobic domain (α(2)δ-1ΔC-term). We find that the majority of α(2)δ-1ΔC-term is soluble and secreted into the medium, but unexpectedly, some of the protein remains associated with detergent-resistant membranes, also termed lipid rafts, and is extrinsically bound to the plasma membrane. Furthermore, heterologous co-expression of α(2)δ-1ΔC-term with Ca(V)2.1/β1b results in a substantial enhancement of the calcium channel currents, albeit less than that produced by wild-type α(2)δ-1. These results call into question the role of membrane anchoring of α(2)δ subunits for calcium current enhancement.
Collapse
Affiliation(s)
- Ivan Kadurin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.
| | | | | | | | | | | | | | | |
Collapse
|
49
|
Calcium channel auxiliary α2δ and β subunits: trafficking and one step beyond. Nat Rev Neurosci 2012; 13:542-55. [PMID: 22805911 DOI: 10.1038/nrn3311] [Citation(s) in RCA: 264] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The voltage-gated calcium channel α(2)δ and β subunits are traditionally considered to be auxiliary subunits that enhance channel trafficking, increase the expression of functional calcium channels at the plasma membrane and influence the channels' biophysical properties. Accumulating evidence indicates that these subunits may also have roles in the nervous system that are not directly linked to calcium channel function. For example, β subunits may act as transcriptional regulators, and certain α(2)δ subunits may function in synaptogenesis. The aim of this Review is to examine both the classic and novel roles for these auxiliary subunits in voltage-gated calcium channel function and beyond.
Collapse
|
50
|
Beqollari D, Kammermeier PJ. The interaction between mGluR1 and the calcium channel Cav₂.₁ preserves coupling in the presence of long Homer proteins. Neuropharmacology 2012; 66:302-10. [PMID: 22659088 DOI: 10.1016/j.neuropharm.2012.05.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Revised: 05/18/2012] [Accepted: 05/21/2012] [Indexed: 11/29/2022]
Abstract
Group I metabotropic glutamate receptors (mGluR1 and 5) are G protein coupled receptors that regulate neuronal activity in a number of ways. Some of the most well studied functions of group I mGluRs, such as initiation of multiple forms of mGluR-dependent long-term depression, require receptor localization near the post-synaptic density (PSD). This localization is in turn dependent on the Homer family of scaffolding proteins which bind to a small motif on the distal C-termini of mGluR1 and 5, localize the receptors near the PSD, strengthen coupling to post-synaptic effectors and simultaneously uncouple the mGluRs from extra-synaptic effectors such as voltage dependent ion channels. Here the selectivity of this uncoupling process was examined by testing the ability of Homer-2b to uncouple mGluR1 from multiple voltage dependent calcium channels including Ca(V2.2) (N-type), Ca(V3.2) (T-type), and Ca(V2.1) (P/Q-type) expressed in rat sympathetic neurons from the superior cervical ganglion (SCG). Of these, only the mGluR1-Ca(V2.1) modulatory pathway was insensitive to Homer-2b expression. Uncoupling from this channel was achieved by co-expression of an mGluR1 C-terminal protein designed to disrupt a previously described direct interaction between these two proteins, suggesting that this interaction allows incorporation of Ca(V2.1) into the mGluR1/Homer signaling complex, thereby preserving modulation in the presence of scaffolding Homer proteins. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.
Collapse
Affiliation(s)
- Donald Beqollari
- University of Rochester Medical Center, Department of Pharmacology and Physiology, Rochester, NY 14642, USA
| | | |
Collapse
|