1
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Kelly MM, Sharma K, Wright CS, Yi X, Reyes Fernandez PC, Gegg AT, Gorrell TA, Noonan ML, Baghdady A, Sieger JA, Dolphin AC, Warden SJ, Deosthale P, Plotkin LI, Sankar U, Hum JM, Robling AG, Farach-Carson MC, Thompson WR. Loss of the auxiliary α 2δ 1 voltage-sensitive calcium channel subunit impairs bone formation and anabolic responses to mechanical loading. JBMR Plus 2024; 8:ziad008. [PMID: 38505532 PMCID: PMC10945727 DOI: 10.1093/jbmrpl/ziad008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 10/31/2023] [Accepted: 11/27/2023] [Indexed: 03/21/2024] Open
Abstract
Voltage-sensitive calcium channels (VSCCs) influence bone structure and function, including anabolic responses to mechanical loading. While the pore-forming (α1) subunit of VSCCs allows Ca2+ influx, auxiliary subunits regulate the biophysical properties of the pore. The α2δ1 subunit influences gating kinetics of the α1 pore and enables mechanically induced signaling in osteocytes; however, the skeletal function of α2δ1 in vivo remains unknown. In this work, we examined the skeletal consequences of deleting Cacna2d1, the gene encoding α2δ1. Dual-energy X-ray absorptiometry and microcomputed tomography imaging demonstrated that deletion of α2δ1 diminished bone mineral content and density in both male and female C57BL/6 mice. Structural differences manifested in both trabecular and cortical bone for males, while the absence of α2δ1 affected only cortical bone in female mice. Deletion of α2δ1 impaired skeletal mechanical properties in both sexes, as measured by three-point bending to failure. While no changes in osteoblast number or activity were found for either sex, male mice displayed a significant increase in osteoclast number, accompanied by increased eroded bone surface and upregulation of genes that regulate osteoclast differentiation. Deletion of α2δ1 also rendered the skeleton insensitive to exogenous mechanical loading in males. While previous work demonstrates that VSCCs are essential for anabolic responses to mechanical loading, the mechanism by which these channels sense and respond to force remained unclear. Our data demonstrate that the α2δ1 auxiliary VSCC subunit functions to maintain baseline bone mass and strength through regulation of osteoclast activity and also provides skeletal mechanotransduction in male mice. These data reveal a molecular player in our understanding of the mechanisms by which VSCCs influence skeletal adaptation.
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Affiliation(s)
- Madison M Kelly
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN 46202, United States
- College of Osteopathic Medicine, Marian University, Indianapolis, IN 46222, United States
| | - Karan Sharma
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN 46202, United States
- College of Osteopathic Medicine, Marian University, Indianapolis, IN 46222, United States
| | - Christian S Wright
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN 46202, United States
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
| | - Xin Yi
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN 46202, United States
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
| | - Perla C Reyes Fernandez
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN 46202, United States
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
| | - Aaron T Gegg
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN 46202, United States
| | - Taylor A Gorrell
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN 46202, United States
| | - Megan L Noonan
- Department of Medical and Molecular Genetics, Indiana University, Indianapolis, IN 46202, United States
| | - Ahmed Baghdady
- College of Osteopathic Medicine, Marian University, Indianapolis, IN 46222, United States
| | - Jacob A Sieger
- College of Osteopathic Medicine, Marian University, Indianapolis, IN 46222, United States
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College of London, Gower Street, London WC1E 6BT, United Kingdom
| | - Stuart J Warden
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN 46202, United States
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
- La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Melbourne Victoria 3086, DX 211319, Australia
| | - Padmini Deosthale
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
- Department of Anatomy, Cell Biology, & Physiology, Indiana University, Indianapolis, IN 46202, United States
| | - Lilian I Plotkin
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
- Department of Anatomy, Cell Biology, & Physiology, Indiana University, Indianapolis, IN 46202, United States
| | - Uma Sankar
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
- Department of Anatomy, Cell Biology, & Physiology, Indiana University, Indianapolis, IN 46202, United States
| | - Julia M Hum
- College of Osteopathic Medicine, Marian University, Indianapolis, IN 46222, United States
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
| | - Alexander G Robling
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
- Department of Anatomy, Cell Biology, & Physiology, Indiana University, Indianapolis, IN 46202, United States
| | - Mary C Farach-Carson
- Department of Diagnostic & Biomedical Sciences, University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, United States
| | - William R Thompson
- Department of Physical Therapy, School of Health and Human Sciences, Indiana University, Indianapolis, IN 46202, United States
- College of Osteopathic Medicine, Marian University, Indianapolis, IN 46222, United States
- Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN 46202, United States
- Department of Anatomy, Cell Biology, & Physiology, Indiana University, Indianapolis, IN 46202, United States
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2
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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3
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Dahimene S, Page KM, Nieto-Rostro M, Pratt WS, Dolphin AC. The Interplay Between Splicing of Two Exon Combinations Differentially Affects Membrane Targeting and Function of Human Ca V2.2. Function (Oxf) 2023; 5:zqad060. [PMID: 38020068 PMCID: PMC10666670 DOI: 10.1093/function/zqad060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/16/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
N-type calcium channels (CaV2.2) are predominantly localized in presynaptic terminals, and are particularly important for pain transmission in the spinal cord. Furthermore, they have multiple isoforms, conferred by alternatively spliced or cassette exons, which are differentially expressed. Here, we have examined alternatively spliced exon47 variants that encode a long or short C-terminus in human CaV2.2. In the Ensembl database, all short exon47-containing transcripts were associated with the absence of exon18a, therefore, we also examined the effect of inclusion or absence of exon18a, combinatorially with the exon47 splice variants. We found that long exon47, only in the additional presence of exon18a, results in CaV2.2 currents that have a 3.6-fold greater maximum conductance than the other three combinations. In contrast, cell-surface expression of CaV2.2 in both tsA-201 cells and hippocampal neurons is increased ∼4-fold by long exon47, relative to short exon47, in either the presence or the absence of exon18a. This surprising discrepancy between trafficking and function indicates that cell-surface expression is enhanced by long exon47, independently of exon18a. However, in the presence of long exon47, exon18a mediates an additional permissive effect on CaV2.2 gating. We also investigated the single-nucleotide polymorphism in exon47 that has been linked to schizophrenia and Parkinson's disease, which we found is only non-synonymous in the short exon47 C-terminal isoform, resulting in two minor alleles. This study highlights the importance of investigating the combinatorial effects of exon inclusion, rather than each in isolation, in order to increase our understanding of calcium channel function.
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Affiliation(s)
- Shehrazade Dahimene
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Karen M Page
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Manuela Nieto-Rostro
- 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
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
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4
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Topczewska A, Giacalone E, Pratt WS, Migliore M, Dolphin AC, Shah MM. T-type Ca 2+ and persistent Na + currents synergistically elevate ventral, not dorsal, entorhinal cortical stellate cell excitability. Cell Rep 2023; 42:112699. [PMID: 37368752 PMCID: PMC10687207 DOI: 10.1016/j.celrep.2023.112699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 03/08/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Dorsal and ventral medial entorhinal cortex (mEC) regions have distinct neural network firing patterns to differentially support functions such as spatial memory. Accordingly, mEC layer II dorsal stellate neurons are less excitable than ventral neurons. This is partly because the densities of inhibitory conductances are higher in dorsal than ventral neurons. Here, we report that T-type Ca2+ currents increase 3-fold along the dorsal-ventral axis in mEC layer II stellate neurons, with twice as much CaV3.2 mRNA in ventral mEC compared with dorsal mEC. Long depolarizing stimuli trigger T-type Ca2+ currents, which interact with persistent Na+ currents to elevate the membrane voltage and spike firing in ventral, not dorsal, neurons. T-type Ca2+ currents themselves prolong excitatory postsynaptic potentials (EPSPs) to enhance their summation and spike coupling in ventral neurons only. These findings indicate that T-type Ca2+ currents critically influence the dorsal-ventral mEC stellate neuron excitability gradient and, thereby, mEC dorsal-ventral circuit activity.
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Affiliation(s)
| | | | - Wendy S Pratt
- Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Michele Migliore
- Institute of Biophysics, National Research Council, 90146 Palermo, Italy
| | - Annette C Dolphin
- Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Mala M Shah
- Pharmacology, School of Pharmacy, University College London, London WC1N 4AX, UK.
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Nieto-Rostro M, Patel R, Dickenson AH, Dolphin AC. Nerve injury increases native Ca V 2.2 trafficking in dorsal root ganglion mechanoreceptors. Pain 2023; 164:1264-1279. [PMID: 36524581 PMCID: PMC10184561 DOI: 10.1097/j.pain.0000000000002846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/16/2022] [Accepted: 11/23/2022] [Indexed: 12/23/2022]
Abstract
ABSTRACT Neuronal N-type (Ca V 2.2) voltage-gated calcium channels are essential for neurotransmission from primary afferent terminals in the dorsal horn. In this study, we have used a knockin mouse containing Ca V 2.2 with an inserted extracellular hemagglutinin tag (Ca V 2.2_HA), to visualise the pattern of expression of endogenous Ca V 2.2 in dorsal root ganglion (DRG) neurons and their primary afferents in the dorsal horn. We examined the effect of partial sciatic nerve ligation (PSNL) and found an increase in Ca V 2.2_HA only in large and medium dorsal root ganglion neurons and also in deep dorsal horn synaptic terminals. Furthermore, there is a parallel increase in coexpression with GFRα1, present in a population of low threshold mechanoreceptors, both in large DRG neurons and in their terminals. The increased expression of Ca V 2.2_HA in these DRG neurons and their terminals is dependent on the presence of the auxiliary subunit α 2 δ-1, which is required for channel trafficking to the cell surface and to synaptic terminals, and it likely contributes to enhanced synaptic transmission at these synapses following PSNL. By contrast, the increase in GFRα1 is not altered in α 2 δ-1-knockout mice. We also found that following PSNL, there is patchy loss of glomerular synapses immunoreactive for Ca V 2.2_HA and CGRP or IB4, restricted to the superficial layers of the dorsal horn. This reduction is not dependent on α 2 δ-1 and likely reflects partial deafferentation of C-nociceptor presynaptic terminals. Therefore, in this pain model, we can distinguish 2 different events affecting specific DRG terminals, with opposite consequences for Ca V 2.2_HA expression and function in the dorsal horn.
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Affiliation(s)
- Manuela Nieto-Rostro
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Ryan Patel
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Anthony H. Dickenson
- 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
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6
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Dolphin AC. Distinct pools of synaptic vesicles are released by different calcium channels. Cell Calcium 2023; 112:102729. [PMID: 37011495 DOI: 10.1016/j.ceca.2023.102729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 03/30/2023]
Abstract
Mueller et al. [1] uncover distinct roles for CaV1 and CaV2 channels in neurotransmitter release at the C. elegans neuromuscular junction. Although nanodomain coupling occurs via clustered CaV2 channels, evidence is also presented that release of a separate vesicular pool is mediated by more peripheral, dispersed CaV1 channels, requiring obligatory coupling with RYR to amplify the Ca2+ signal.
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.
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7
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Pilch KS, Ramgoolam KH, Dolphin AC. Involvement of Ca V 2.2 channels and α 2 δ-1 in homeostatic synaptic plasticity in cultured hippocampal neurons. J Physiol 2022; 600:5333-5351. [PMID: 36377048 PMCID: PMC10107484 DOI: 10.1113/jp283600] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
Abstract
In the mammalian brain, presynaptic CaV 2 channels play a pivotal role in synaptic transmission by mediating fast neurotransmitter exocytosis via influx of Ca2+ into the active zone of presynaptic terminals. However, the distribution and modulation of CaV 2.2 channels at plastic hippocampal synapses remains to be elucidated. Here, we assess CaV 2.2 channels during homeostatic synaptic plasticity, a compensatory form of homeostatic control preventing excessive or insufficient neuronal activity during which extensive active zone remodelling has been described. We show that chronic silencing of neuronal activity in mature hippocampal cultures resulted in elevated presynaptic Ca2+ transients, mediated by increased levels of CaV 2.2 channels at the presynaptic site. This work focused further on the role of α2 δ-1 subunits, important regulators of synaptic transmission and CaV 2.2 channel abundance at the presynaptic membrane. We found that α2 δ-1 overexpression reduces the contribution of CaV 2.2 channels to total Ca2+ flux without altering the amplitude of the Ca2+ transients. Levels of endogenous α2 δ-1 decreased during homeostatic synaptic plasticity, whereas the overexpression of α2 δ-1 prevented homeostatic synaptic plasticity in hippocampal neurons. Together, this study reveals a key role for CaV 2.2 channels and novel roles for α2 δ-1 during synaptic plastic adaptation. KEY POINTS: The roles of CaV 2.2 channels and α2 δ-1 in homeostatic synaptic plasticity in hippocampal neurons in culture were examined. Chronic silencing of neuronal activity resulted in elevated presynaptic Ca2+ transients, mediated by increased levels of CaV 2.2 channels at presynaptic sites. The level of endogenous α2 δ-1 decreased during homeostatic synaptic plasticity, whereas overexpression of α2 δ-1 prevented homeostatic synaptic plasticity in hippocampal neurons. Together, this study reveals a key role for CaV 2.2 channels and novel roles for α2 δ-1 during synaptic plastic adaptation.
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Affiliation(s)
- Kjara S. Pilch
- Department of NeurosciencePhysiology and PharmacologyUniversity College LondonLondonUK
| | - Krishma H. Ramgoolam
- Department of NeurosciencePhysiology and PharmacologyUniversity College LondonLondonUK
| | - Annette C. Dolphin
- Department of NeurosciencePhysiology and PharmacologyUniversity College LondonLondonUK
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8
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Ramgoolam KH, Dolphin AC. Capsaicin-Induced Endocytosis of Endogenous Presynaptic Ca V2.2 in DRG-Spinal Cord Co-Cultures Inhibits Presynaptic Function. Function (Oxf) 2022; 4:zqac058. [PMID: 36540890 PMCID: PMC9761886 DOI: 10.1093/function/zqac058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/15/2022] [Accepted: 11/15/2022] [Indexed: 11/26/2022] Open
Abstract
The N-type calcium channel, CaV2.2 is key to neurotransmission from the primary afferent terminals of dorsal root ganglion (DRG) neurons to their postsynaptic targets in the spinal cord. In this study, we have utilized CaV2.2_HA knock-in mice, because the exofacial epitope tag in CaV2.2_HA enables accurate detection and localization of endogenous CaV2.2. CaV2.2_HA knock-in mice were used as a source of DRGs to exclusively study the presynaptic expression of N-type calcium channels in co-cultures between DRG neurons and wild-type spinal cord neurons. CaV2.2_HA is strongly expressed on the cell surface, particularly in TRPV1-positive small and medium DRG neurons. Super-resolution images of the presynaptic terminals revealed an increase in CaV2.2_HA expression and increased association with the postsynaptic marker Homer over time in vitro. Brief application of the TRPV1 agonist, capsaicin, resulted in a significant down-regulation of cell surface CaV2.2_HA expression in DRG neuron somata. At their presynaptic terminals, capsaicin caused a reduction in CaV2.2_HA proximity to and co-localization with the active zone marker RIM 1/2, as well as a lower contribution of N-type channels to single action potential-mediated Ca2+ influx. The mechanism of this down-regulation of CaV2.2_HA involves a Rab11a-dependent trafficking process, since dominant-negative Rab11a (S25N) occludes the effect of capsaicin on presynaptic CaV2.2_HA expression, and also prevents the effect of capsaicin on action potential-induced Ca2+ influx. Taken together, these data suggest that capsaicin causes a decrease in cell surface CaV2.2_HA expression in DRG terminals via a Rab11a-dependent endosomal trafficking pathway.
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Affiliation(s)
- Krishma H Ramgoolam
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
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9
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Dahimene S, von Elsner L, Holling T, Mattas LS, Pickard J, Lessel D, Pilch KS, Kadurin I, Pratt WS, Zhulin IB, Dai H, Hempel M, Ruzhnikov MRZ, Kutsche K, Dolphin AC. Biallelic CACNA2D1 loss-of-function variants cause early-onset developmental epileptic encephalopathy. Brain 2022; 145:2721-2729. [PMID: 35293990 PMCID: PMC9420018 DOI: 10.1093/brain/awac081] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/26/2022] [Accepted: 02/13/2022] [Indexed: 11/14/2022] Open
Abstract
Voltage-gated calcium (CaV) channels form three subfamilies (CaV1-3). The CaV1 and CaV2 channels are heteromeric, consisting of an α1 pore-forming subunit, associated with auxiliary CaVβ and α2δ subunits. The α2δ subunits are encoded in mammals by four genes, CACNA2D1-4. They play important roles in trafficking and function of the CaV channel complexes. Here we report biallelic variants in CACNA2D1, encoding the α2δ-1 protein, in two unrelated individuals showing a developmental and epileptic encephalopathy. Patient 1 has a homozygous frameshift variant c.818_821dup/p.(Ser275Asnfs*13) resulting in nonsense-mediated mRNA decay of the CACNA2D1 transcripts, and absence of α2δ-1 protein detected in patient-derived fibroblasts. Patient 2 is compound heterozygous for an early frameshift variant c.13_23dup/p.(Leu9Alafs*5), highly probably representing a null allele and a missense variant c.626G>A/p.(Gly209Asp). Our functional studies show that this amino-acid change severely impairs the function of α2δ-1 as a calcium channel subunit, with strongly reduced trafficking of α2δ-1G209D to the cell surface and a complete inability of α2δ-1G209D to increase the trafficking and function of CaV2 channels. Thus, biallelic loss-of-function variants in CACNA2D1 underlie the severe neurodevelopmental disorder in these two patients. Our results demonstrate the critical importance and non-interchangeability of α2δ-1 and other α2δ proteins for normal human neuronal development.
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Affiliation(s)
- Shehrazade Dahimene
- Department of Neuroscience Physiology and Pharmacology, University College London (UCL), London WC1E 6BT, UK
| | - Leonie von Elsner
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Tess Holling
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Lauren S Mattas
- Neurology and Neurological Sciences, Pediatrics, Division of Medical Genetics, Stanford University and Lucile Packard Children's Hospital, Palo Alto, CA 94304, USA
| | - Jess Pickard
- Department of Neuroscience Physiology and Pharmacology, University College London (UCL), London WC1E 6BT, UK
| | - Davor Lessel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Kjara S Pilch
- Department of Neuroscience Physiology and Pharmacology, University College London (UCL), London WC1E 6BT, UK
| | - Ivan Kadurin
- Department of Neuroscience Physiology and Pharmacology, University College London (UCL), London WC1E 6BT, UK
| | - Wendy S Pratt
- Department of Neuroscience Physiology and Pharmacology, University College London (UCL), London WC1E 6BT, UK
| | - Igor B Zhulin
- Department of Microbiology and Translational Data Analytics Institute, The Ohio State University, Columbus, OH, 43210, USA
| | - Hongzheng Dai
- Department of Molecular and Human Genetics, Baylor College of Medicine/NGS-Molecular, Baylor Genetics, Houston, TX, USA
| | - Maja Hempel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Maura R Z Ruzhnikov
- Neurology and Neurological Sciences, Pediatrics, Division of Medical Genetics, Stanford University and Lucile Packard Children's Hospital, Palo Alto, CA 94304, USA
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Annette C Dolphin
- Department of Neuroscience Physiology and Pharmacology, University College London (UCL), London WC1E 6BT, UK
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10
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Kadurin I, Dahimene S, Page KM, Ellaway JIJ, Chaggar K, Troeberg L, Nagase H, Dolphin AC. ADAM17 Mediates Proteolytic Maturation of Voltage-Gated Calcium Channel Auxiliary α 2δ Subunits, and Enables Calcium Current Enhancement. Function (Oxf) 2022; 3:zqac013. [PMID: 35462614 PMCID: PMC9016415 DOI: 10.1093/function/zqac013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 01/07/2023] Open
Abstract
The auxiliary α2δ subunits of voltage-gated calcium (CaV) channels are key to augmenting expression and function of CaV1 and CaV2 channels, and are also important drug targets in several therapeutic areas, including neuropathic pain. The α2δ proteins are translated as preproteins encoding both α2 and δ, and post-translationally proteolyzed into α2 and δ subunits, which remain associated as a complex. In this study, we have identified ADAM17 as a key protease involved in proteolytic processing of pro-α2δ-1 and α2δ-3 subunits. We provide three lines of evidence: First, proteolytic cleavage is inhibited by chemical inhibitors of particular metalloproteases, including ADAM17. Second, proteolytic cleavage of both α2δ-1 and α2δ-3 is markedly reduced in cell lines by knockout of ADAM17 but not ADAM10. Third, proteolytic cleavage is reduced by the N-terminal active domain of TIMP-3 (N-TIMP-3), which selectively inhibits ADAM17. We have found previously that proteolytic cleavage into mature α2δ is essential for the enhancement of CaV function, and in agreement, knockout of ADAM17 inhibited the ability of α2δ-1 to enhance both CaV2.2 and CaV1.2 calcium currents. Finally, our data also indicate that the main site of proteolytic cleavage of α2δ-1 is the Golgi apparatus, although cleavage may also occur at the plasma membrane. Thus, our study identifies ADAM17 as a key protease required for proteolytic maturation of α2δ-1 and α2δ-3, and thus a potential drug target in neuropathic pain.
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Affiliation(s)
- Ivan Kadurin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Shehrazade Dahimene
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Karen M Page
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Joseph I J Ellaway
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Kanchan Chaggar
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Linda Troeberg
- Norwich Medical School, University of East Anglia, Norwich NR4 7UQ, UK
| | - Hideaki Nagase
- Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
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11
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Gumerov VM, Andrianova EP, Matilla MA, Page KM, Monteagudo-Cascales E, Dolphin AC, Krell T, Zhulin IB. Amino acid sensor conserved from bacteria to humans. Proc Natl Acad Sci U S A 2022; 119:e2110415119. [PMID: 35238638 PMCID: PMC8915833 DOI: 10.1073/pnas.2110415119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 01/10/2022] [Indexed: 11/18/2022] Open
Abstract
SignificanceAmino acids are the building blocks of life and important signaling molecules. Despite their common structure, no universal mechanism for amino acid recognition by cellular receptors is currently known. We discovered a simple motif, which binds amino acids in various receptor proteins from all major life-forms. In humans, this motif is found in subunits of calcium channels that are implicated in pain and neurodevelopmental disorders. Our findings suggest that γ-aminobutyric acid-derived drugs bind to the same motif in human proteins that binds natural ligands in bacterial receptors, thus enabling future improvement of important drugs.
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Affiliation(s)
- Vadim M. Gumerov
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH 43210
| | - Ekaterina P. Andrianova
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH 43210
| | - Miguel A. Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, E-18008 Granada, Spain
| | - Karen M. Page
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Elizabet Monteagudo-Cascales
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, E-18008 Granada, Spain
| | - Annette C. Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, E-18008 Granada, Spain
| | - Igor B. Zhulin
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH 43210
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12
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Alberts B, Colbran RJ, Dolphin AC, Pitt GS, Südhof TC. Proteolytic regulation of calcium channels - avoiding controversy. Fac Rev 2022; 11:5. [PMID: 35373215 PMCID: PMC8958896 DOI: 10.12703/r-01-000006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The publication of papers containing data obtained with suboptimal rigor in the experimental design and choice of key reagents, such as antibodies, can result in a lack of reproducibility and generate controversy that can both needlessly divert resources and, in some cases, damage public perception of the scientific enterprise. This exemplary paper by Buonarati et al. (2018)1 shows how a previously published, potentially important paper on calcium channel regulation falls short of the necessary mark, and aims to resolve the resulting controversy.
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13
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Meyer JO, Dolphin AC. Rab11-dependent recycling of calcium channels is mediated by auxiliary subunit α 2δ-1 but not α 2δ-3. Sci Rep 2021; 11:10256. [PMID: 33986433 PMCID: PMC8119971 DOI: 10.1038/s41598-021-89820-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/16/2021] [Indexed: 11/18/2022] Open
Abstract
N-type voltage-gated calcium channels (CaV2.2) are predominantly expressed at presynaptic terminals, and their function is regulated by auxiliary α2δ and β subunits. All four mammalian α2δ subunits enhance calcium currents through CaV1 and CaV2 channels, and this increase is attributed, in part, to increased CaV expression at the plasma membrane. In the present study we provide evidence that α2δ-1, like α2δ-2, is recycled to the plasma membrane through a Rab11a-dependent endosomal recycling pathway. Using a dominant-negative Rab11a mutant, Rab11a(S25N), we show that α2δ-1 increases plasma membrane CaV2.2 expression by increasing the rate and extent of net forward CaV2.2 trafficking in a Rab11a-dependent manner. Dominant-negative Rab11a also reduces the ability of α2δ-1 to increase CaV2.2 expression on the cell-surface of hippocampal neurites. In contrast, α2δ-3 does not enhance rapid forward CaV2.2 trafficking, regardless of whether Rab11a(S25N) is present. In addition, whole-cell CaV2.2 currents are reduced by co-expression of Rab11a(S25N) in the presence of α2δ-1, but not α2δ-3. Taken together these data suggest that α2δ subtypes participate in distinct trafficking pathways which in turn influence the localisation and function of CaV2.2.
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Affiliation(s)
- James O Meyer
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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14
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Abstract
"Ion Channels and Neuropharmacology: From the Past to the Future" is the main theme of articles in Volume 60 of the Annual Review of Pharmacology and Toxicology. Reviews in this volume discuss a wide spectrum of therapeutically relevant ion channels and GPCRs with a particular emphasis on structural studies that elucidate drug binding sites and mechanisms of action. The regulation of ion channels by second messengers, including Ca2+ and cyclic AMP, and lipid mediators is also highly relevant to several of the ion channels discussed, including KCNQ channels, HCN channels, L-type Ca2+ channels, and AMPA receptors, as well as the aquaporin channels. Molecular identification of exactly where drugs bind in the structure not only elucidates their mechanism of action but also aids future structure-based drug discovery efforts to focus on relevant pharmacophores. The ion channels discussed here are targets for multiple nervous system diseases, including epilepsy and neuropathic pain. This theme complements several previous themes, including "New Therapeutic Targets," "New Approaches for Studying Drug and Toxicant Action: Applications to Drug Discovery and Development," and "New Methods and Novel Therapeutic Approaches in Pharmacology and Toxicology."
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom;
| | - Paul A Insel
- Departments of Pharmacology and Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Terrence F Blaschke
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Urs A Meyer
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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15
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Abstract
Voltage-gated calcium channels are the principal conduits for depolarization-mediated Ca2+ entry into excitable cells. In this review, the biophysical properties of the relevant members of this family of channels, those that are present in presynaptic terminals, will be discussed in relation to their function in mediating neurotransmitter release. Voltage-gated calcium channels have properties that ensure they are specialized for particular roles, for example, differences in their activation voltage threshold, their various kinetic properties, and their voltage-dependence of inactivation. All these attributes play into the ability of the various voltage-gated calcium channels to participate in different patterns of presynaptic vesicular release. These include synaptic transmission resulting from single action potentials, and longer-term changes mediated by bursts or trains of action potentials, as well as release resulting from graded changes in membrane potential in specialized sensory synapses.
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK,Address correspondence to A.C.D. (e-mail: )
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16
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Meyer JO, Dahimene S, Page KM, Ferron L, Kadurin I, Ellaway JIJ, Zhao P, Patel T, Rothwell SW, Lin P, Pratt WS, Dolphin AC. Disruption of the Key Ca 2+ Binding Site in the Selectivity Filter of Neuronal Voltage-Gated Calcium Channels Inhibits Channel Trafficking. Cell Rep 2020; 29:22-33.e5. [PMID: 31577951 PMCID: PMC6899504 DOI: 10.1016/j.celrep.2019.08.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 06/20/2019] [Accepted: 08/22/2019] [Indexed: 12/05/2022] Open
Abstract
Voltage-gated calcium channels are exquisitely Ca2+ selective, conferred primarily by four conserved pore-loop glutamate residues contributing to the selectivity filter. There has been little previous work directly measuring whether the trafficking of calcium channels requires their ability to bind Ca2+ in the selectivity filter or to conduct Ca2+. Here, we examine trafficking of neuronal CaV2.1 and 2.2 channels with mutations in their selectivity filter and find reduced trafficking to the cell surface in cell lines. Furthermore, in hippocampal neurons, there is reduced trafficking to the somatic plasma membrane, into neurites, and to presynaptic terminals. However, the CaV2.2 selectivity filter mutants are still influenced by auxiliary α2δ subunits and, albeit to a reduced extent, by β subunits, indicating the channels are not grossly misfolded. Our results indicate that Ca2+ binding in the pore of CaV2 channels may promote their correct trafficking, in combination with auxiliary subunits. Furthermore, physiological studies utilizing selectivity filter mutant CaV channels should be interpreted with caution. Selectivity filter mutations in CaV2 channels block inward Ba2+ currents Surprisingly, these mutations severely reduce trafficking of the CaV2 channels Pore mutant N-type channels show reduced expression in presynaptic terminals Pore mutant channels still require β and α2δ and thus are not grossly misfolded
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Affiliation(s)
- James O Meyer
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Shehrazade Dahimene
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Karen M Page
- 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
| | - Ivan Kadurin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Joseph I J Ellaway
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Pengxiang Zhao
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Tarun Patel
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Simon W Rothwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Peipeng Lin
- 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
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK.
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17
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Dolphin AC, Kadurin I. Fight or flight: The culprit is lurking in the neighbourhood. Cell Calcium 2020; 87:102180. [DOI: 10.1016/j.ceca.2020.102180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 02/10/2020] [Accepted: 02/10/2020] [Indexed: 12/30/2022]
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18
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Harrison PJ, Tunbridge EM, Dolphin AC, Hall J. Voltage-gated calcium channel blockers for psychiatric disorders: genomic reappraisal. Br J Psychiatry 2020; 216:250-253. [PMID: 31230606 PMCID: PMC7557861 DOI: 10.1192/bjp.2019.157] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 04/24/2019] [Accepted: 05/25/2019] [Indexed: 12/11/2022]
Abstract
We reappraise the psychiatric potential of calcium channel blockers (CCBs). First, voltage-gated calcium channels are risk genes for several disorders. Second, use of CCBs is associated with altered psychiatric risks and outcomes. Third, research shows there is an opportunity for brain-selective CCBs, which are better suited to psychiatric indications.
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Affiliation(s)
- Paul J. Harrison
- Professor, Department of Psychiatry, University of Oxford; and Honorary Consultant Psychiatrist, Oxford Health NHS Foundation Trust, UK
| | - Elizabeth M. Tunbridge
- Associate Professor, Department of Psychiatry, University of Oxford; and Oxford Health NHS Foundation Trust, UK
| | - Annette C. Dolphin
- Professor, Department of Neuroscience, Physiology, and Pharmacology, University College London, UK
| | - Jeremy Hall
- Professor, Neuroscience and Mental Health Research Unit, Cardiff University, UK
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19
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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.
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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.
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20
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Ferron L, Novazzi CG, Pilch KS, Moreno C, Ramgoolam K, Dolphin AC. FMRP regulates presynaptic localization of neuronal voltage gated calcium channels. Neurobiol Dis 2020; 138:104779. [PMID: 31991246 PMCID: PMC7152798 DOI: 10.1016/j.nbd.2020.104779] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/09/2020] [Accepted: 01/24/2020] [Indexed: 12/31/2022] Open
Abstract
Fragile X syndrome (FXS), the most common form of inherited intellectual disability and autism, results from the loss of fragile X mental retardation protein (FMRP). We have recently identified a direct interaction of FMRP with voltage-gated Ca2+ channels that modulates neurotransmitter release. In the present study we used a combination of optophysiological tools to investigate the impact of FMRP on the targeting of voltage-gated Ca2+ channels to the active zones in neuronal presynaptic terminals. We monitored Ca2+ transients at synaptic boutons of dorsal root ganglion (DRG) neurons using the genetically-encoded Ca2+ indicator GCaMP6f tagged to synaptophysin. We show that knock-down of FMRP induces an increase of the amplitude of the Ca2+ transient in functionally-releasing presynaptic terminals, and that this effect is due to an increase of N-type Ca2+ channel contribution to the total Ca2+ transient. Dynamic regulation of CaV2.2 channel trafficking is key to the function of these channels in neurons. Using a CaV2.2 construct with an α-bungarotoxin binding site tag, we further investigate the impact of FMRP on the trafficking of CaV2.2 channels. We show that forward trafficking of CaV2.2 channels from the endoplasmic reticulum to the plasma membrane is reduced when co-expressed with FMRP. Altogether our data reveal a critical role of FMRP on localization of CaV channels to the presynaptic terminals and how its defect in a context of FXS can profoundly affect synaptic transmission. Loss of FMRP increases presynaptic Ca2+ transients. FMRP is a negative regulator of presynaptic Cav2.2 channel abundance. FMRP reduces the forward trafficking of Cav2.2 channels from ER to plasma membrane. Distal part of FMRP carboxy terminus is key for interaction with Cav2.2 channels.
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Affiliation(s)
- Laurent Ferron
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK.
| | - Cesare G Novazzi
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Kjara S Pilch
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Cristian Moreno
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Krishma Ramgoolam
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
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21
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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: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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
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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.
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22
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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.
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
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23
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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.
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24
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Abstract
Auxiliary α2δ subunits are important proteins for trafficking of voltage-gated calcium channels (CaV) at the active zones of synapses. We have previously shown that the post-translational proteolytic cleavage of α2δ is essential for their modulatory effects on the trafficking of N-type (CaV2.2) calcium channels (Kadurin et al., 2016). We extend these results here by showing that the probability of presynaptic vesicular release is reduced when an uncleaved α2δ is expressed in rat neurons and that this inhibitory effect is reversed when cleavage of α2δ is restored. We also show that asynchronous release is influenced by the maturation of α2δ-1, highlighting the role of CaV channels in this component of vesicular release. We present additional evidence that CaV2.2 co-immunoprecipitates preferentially with cleaved wild-type α2δ. Our data indicate that the proteolytic maturation increases the association of α2δ-1 with CaV channel complex and is essential for its function on synaptic release.
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Affiliation(s)
- Laurent Ferron
- Department of Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUnited Kingdom
| | - Ivan Kadurin
- Department of Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUnited Kingdom
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUnited Kingdom
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25
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Kanellopoulos AH, Koenig J, Huang H, Pyrski M, Millet Q, Lolignier S, Morohashi T, Gossage SJ, Jay M, Linley JE, Baskozos G, Kessler BM, Cox JJ, Dolphin AC, Zufall F, Wood JN, Zhao J. Mapping protein interactions of sodium channel Na V1.7 using epitope-tagged gene-targeted mice. EMBO J 2018; 37:427-445. [PMID: 29335280 PMCID: PMC5793798 DOI: 10.15252/embj.201796692] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 11/30/2017] [Accepted: 12/05/2017] [Indexed: 11/24/2022] Open
Abstract
The voltage-gated sodium channel NaV1.7 plays a critical role in pain pathways. We generated an epitope-tagged NaV1.7 mouse that showed normal pain behaviours to identify channel-interacting proteins. Analysis of NaV1.7 complexes affinity-purified under native conditions by mass spectrometry revealed 267 proteins associated with Nav1.7 in vivo The sodium channel β3 (Scn3b), rather than the β1 subunit, complexes with Nav1.7, and we demonstrate an interaction between collapsing-response mediator protein (Crmp2) and Nav1.7, through which the analgesic drug lacosamide regulates Nav1.7 current density. Novel NaV1.7 protein interactors including membrane-trafficking protein synaptotagmin-2 (Syt2), L-type amino acid transporter 1 (Lat1) and transmembrane P24-trafficking protein 10 (Tmed10) together with Scn3b and Crmp2 were validated by co-immunoprecipitation (Co-IP) from sensory neuron extract. Nav1.7, known to regulate opioid receptor efficacy, interacts with the G protein-regulated inducer of neurite outgrowth (Gprin1), an opioid receptor-binding protein, demonstrating a physical and functional link between Nav1.7 and opioid signalling. Further information on physiological interactions provided with this normal epitope-tagged mouse should provide useful insights into the many functions now associated with the NaV1.7 channel.
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Affiliation(s)
| | - Jennifer Koenig
- Molecular Nociception Group, WIBR, University College London, London, UK
| | - Honglei Huang
- TDI Mass Spectrometry Laboratory, Target Discovery Institute, University of Oxford, Oxford, UK
| | - Martina Pyrski
- Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Queensta Millet
- Molecular Nociception Group, WIBR, University College London, London, UK
| | - Stéphane Lolignier
- Molecular Nociception Group, WIBR, University College London, London, UK
- Université Clermont Auvergne, Inserm U1107 Neuro-Dol, Pharmacologie Fondamentale et Clinique de la Douleur, Clermont-Ferrand, France
| | - Toru Morohashi
- Molecular Nociception Group, WIBR, University College London, London, UK
| | - Samuel J Gossage
- Molecular Nociception Group, WIBR, University College London, London, UK
| | - Maude Jay
- Molecular Nociception Group, WIBR, University College London, London, UK
| | - John E Linley
- Molecular Nociception Group, WIBR, University College London, London, UK
- Neuroscience, IMED Biotech Unit, AstraZeneca, Cambridge, UK
| | | | - Benedikt M Kessler
- TDI Mass Spectrometry Laboratory, Target Discovery Institute, University of Oxford, Oxford, UK
| | - James J Cox
- Molecular Nociception Group, WIBR, University College London, London, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Frank Zufall
- Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - John N Wood
- Molecular Nociception Group, WIBR, University College London, London, UK
| | - Jing Zhao
- Molecular Nociception Group, WIBR, University College London, London, UK
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26
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Chemin J, Taiakina V, Monteil A, Piazza M, Guan W, Stephens RF, Kitmitto A, Pang ZP, Dolphin AC, Perez-Reyes E, Dieckmann T, Guillemette JG, Spafford JD. Calmodulin regulates Ca v3 T-type channels at their gating brake. J Biol Chem 2017; 292:20010-20031. [PMID: 28972185 PMCID: PMC5723990 DOI: 10.1074/jbc.m117.807925] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/19/2017] [Indexed: 01/10/2023] Open
Abstract
Calcium (Cav1 and Cav2) and sodium channels possess homologous CaM-binding motifs, known as IQ motifs in their C termini, which associate with calmodulin (CaM), a universal calcium sensor. Cav3 T-type channels, which serve as pacemakers of the mammalian brain and heart, lack a C-terminal IQ motif. We illustrate that T-type channels associate with CaM using co-immunoprecipitation experiments and single particle cryo-electron microscopy. We demonstrate that protostome invertebrate (LCav3) and human Cav3.1, Cav3.2, and Cav3.3 T-type channels specifically associate with CaM at helix 2 of the gating brake in the I-II linker of the channels. Isothermal titration calorimetry results revealed that the gating brake and CaM bind each other with high-nanomolar affinity. We show that the gating brake assumes a helical conformation upon binding CaM, with associated conformational changes to both CaM lobes as indicated by amide chemical shifts of the amino acids of CaM in 1H-15N HSQC NMR spectra. Intact Ca2+-binding sites on CaM and an intact gating brake sequence (first 39 amino acids of the I-II linker) were required in Cav3.2 channels to prevent the runaway gating phenotype, a hyperpolarizing shift in voltage sensitivities and faster gating kinetics. We conclude that the presence of high-nanomolar affinity binding sites for CaM at its universal gating brake and its unique form of regulation via the tuning of the voltage range of activity could influence the participation of Cav3 T-type channels in heart and brain rhythms. Our findings may have implications for arrhythmia disorders arising from mutations in the gating brake or CaM.
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Affiliation(s)
- Jean Chemin
- Institut de Génomique Fonctionnelle, CNRS, INSERM, Université de Montpellier, Montpellier F-34094, France
| | | | - Arnaud Monteil
- Institut de Génomique Fonctionnelle, CNRS, INSERM, Université de Montpellier, Montpellier F-34094, France
| | - Michael Piazza
- Departments of Chemistry, Waterloo, Ontario N2L 3G1, Canada
| | - Wendy Guan
- Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | | | - Ashraf Kitmitto
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9NT, United Kingdom
| | - Zhiping P Pang
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey 08901
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Edward Perez-Reyes
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | | | | | - J David Spafford
- Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
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27
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Kisiswa L, Erice C, Ferron L, Wyatt S, Osório C, Dolphin AC, Davies AM. T-type Ca2+ channels are required for enhanced sympathetic axon growth by TNFα reverse signalling. Open Biol 2017; 7:rsob.160288. [PMID: 28100666 PMCID: PMC5303278 DOI: 10.1098/rsob.160288] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/12/2016] [Indexed: 12/28/2022] Open
Abstract
Tumour necrosis factor receptor 1 (TNFR1)-activated TNFα reverse signalling, in which membrane-integrated TNFα functions as a receptor for TNFR1, enhances axon growth from developing sympathetic neurons and plays a crucial role in establishing sympathetic innervation. Here, we have investigated the link between TNFα reverse signalling and axon growth in cultured sympathetic neurons. TNFR1-activated TNFα reverse signalling promotes Ca2+ influx, and highly selective T-type Ca2+ channel inhibitors, but not pharmacological inhibitors of L-type, N-type and P/Q-type Ca2+ channels, prevented enhanced axon growth. T-type Ca2+ channel-specific inhibitors eliminated Ca2+ spikes promoted by TNFα reverse signalling in axons and prevented enhanced axon growth when applied locally to axons, but not when applied to cell somata. Blocking action potential generation did not affect the effect of TNFα reverse signalling on axon growth, suggesting that propagated action potentials are not required for enhanced axon growth. TNFα reverse signalling enhanced protein kinase C (PKC) activation, and pharmacological inhibition of PKC prevented the axon growth response. These results suggest that TNFα reverse signalling promotes opening of T-type Ca2+ channels along sympathetic axons, which is required for enhanced axon growth.
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Affiliation(s)
- Lilian Kisiswa
- School Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
| | - Clara Erice
- School Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
| | - Laurent Ferron
- Department of Neuroscience, Physiology and Pharmacology, University College London, Andrew Huxley Building, Gower Street, London WC1E 6BT, UK
| | - Sean Wyatt
- School Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
| | - Catarina Osório
- School Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Andrew Huxley Building, Gower Street, London WC1E 6BT, UK
| | - Alun M Davies
- School Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
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28
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Margas W, Ferron L, Nieto-Rostro M, Schwartz A, Dolphin AC. Effect of knockout of α2δ-1 on action potentials in mouse sensory neurons. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0430. [PMID: 27377724 PMCID: PMC4938030 DOI: 10.1098/rstb.2015.0430] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2016] [Indexed: 12/12/2022] Open
Abstract
Gene deletion of the voltage-gated calcium channel auxiliary subunit α2δ-1 has been shown previously to have a cardiovascular phenotype, and a reduction in mechano- and cold sensitivity, coupled with delayed development of neuropathic allodynia. We have also previously shown that dorsal root ganglion (DRG) neuron calcium channel currents were significantly reduced in α2δ-1 knockout mice. To extend our findings in these sensory neurons, we have examined here the properties of action potentials (APs) in DRG neurons from α2δ-1 knockout mice in comparison to their wild-type (WT) littermates, in order to dissect how the calcium channels that are affected by α2δ-1 knockout are involved in setting the duration of individual APs and their firing frequency. Our main findings are that there is reduced Ca2+ entry on single AP stimulation, particularly in the axon proximal segment, reduced AP duration and reduced firing frequency to a 400 ms stimulation in α2δ-1 knockout neurons, consistent with the expected role of voltage-gated calcium channels in these events. Furthermore, lower intracellular Ca2+ buffering also resulted in reduced AP duration, and a lower frequency of AP firing in WT neurons, mimicking the effect of α2δ-1 knockout. By contrast, we did not obtain any consistent evidence for the involvement of Ca2+-activation of large conductance calcium-activated potassium (BK) and small conductance calcium-activated potassium (SK) channels in these events. In conclusion, the reduced Ca2+ elevation as a result of single AP stimulation is likely to result from the reduced duration of the AP in α2δ-1 knockout sensory neurons. This article is part of the themed issue ‘Evolution brings Ca2+ and ATP together to control life and death’.
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Affiliation(s)
- Wojciech Margas
- 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
| | - Manuela Nieto-Rostro
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Arnold Schwartz
- College of Medicine, University of Cincinnati, Cincinnati, OH 45267-0557, USA
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
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29
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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] [What about the content of this article? (0)] [Affiliation(s)] [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
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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
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Page KM, Rothwell SW, Dolphin AC. The CaVβ Subunit Protects the I-II Loop of the Voltage-gated Calcium Channel CaV2.2 from Proteasomal Degradation but Not Oligoubiquitination. J Biol Chem 2016; 291:20402-16. [PMID: 27489103 PMCID: PMC5034038 DOI: 10.1074/jbc.m116.737270] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 11/06/2022] Open
Abstract
CaVβ subunits interact with the voltage-gated calcium channel CaV2.2 on a site in the intracellular loop between domains I and II (the I-II loop). This interaction influences the biophysical properties of the channel and leads to an increase in its trafficking to the plasma membrane. We have shown previously that a mutant CaV2.2 channel that is unable to bind CaVβ subunits (CaV2.2 W391A) was rapidly degraded (Waithe, D., Ferron, L., Page, K. M., Chaggar, K., and Dolphin, A. C. (2011) J. Biol. Chem. 286, 9598-9611). Here we show that, in the absence of CaVβ subunits, a construct consisting of the I-II loop of CaV2.2 was directly ubiquitinated and degraded by the proteasome system. Ubiquitination could be prevented by mutation of all 12 lysine residues in the I-II loop to arginines. Including a palmitoylation motif at the N terminus of CaV2.2 I-II loop was insufficient to target it to the plasma membrane in the absence of CaVβ subunits even when proteasomal degradation was inhibited with MG132 or ubiquitination was prevented by the lysine-to-arginine mutations. In the presence of CaVβ subunit, the palmitoylated CaV2.2 I-II loop was protected from degradation, although oligoubiquitination could still occur, and was efficiently trafficked to the plasma membrane. We propose that targeting to the plasma membrane requires a conformational change in the I-II loop that is induced by binding of the CaVβ subunit.
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Affiliation(s)
- Karen M Page
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Simon W Rothwell
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Annette C Dolphin
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
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31
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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: 201] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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32
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Dahimene S, Page KM, Nieto-Rostro M, Pratt WS, D'Arco M, Dolphin AC. A CaV2.1 N-terminal fragment relieves the dominant-negative inhibition by an Episodic ataxia 2 mutant. Neurobiol Dis 2016; 93:243-56. [PMID: 27260834 PMCID: PMC4940211 DOI: 10.1016/j.nbd.2016.05.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 05/30/2016] [Indexed: 02/08/2023] Open
Abstract
Episodic ataxia 2 (EA2) is an autosomal dominant disorder caused by mutations in the gene CACNA1A that encodes the pore-forming CaV2.1 calcium channel subunit. The majority of EA2 mutations reported so far are nonsense or deletion/insertion mutations predicted to form truncated proteins. Heterologous expression of wild-type CaV2.1, together with truncated constructs that mimic EA2 mutants, significantly suppressed wild-type calcium channel function, indicating that the truncated protein produces a dominant-negative effect (Jouvenceau et al., 2001; Page et al., 2004). A similar finding has been shown for CaV2.2 (Raghib et al., 2001). We show here that a highly conserved sequence in the cytoplasmic N-terminus is involved in this process, for both CaV2.1 and CaV2.2 channels. Additionally, we were able to interfere with the suppressive effect of an EA2 construct by mutating key N-terminal residues within it. We postulate that the N-terminus of the truncated channel plays an essential part in its interaction with the full-length CaV2.1, which prevents the correct folding of the wild-type channel. In agreement with this, we were able to disrupt the interaction between EA2 and the full length channel by co-expressing a free N-terminal peptide.
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Affiliation(s)
- Shehrazade Dahimene
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
| | - Karen M Page
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Manuela Nieto-Rostro
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Wendy S Pratt
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Marianna D'Arco
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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33
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Lana B, Page KM, Kadurin I, Ho S, Nieto-Rostro M, Dolphin AC. Thrombospondin-4 reduces binding affinity of [(3)H]-gabapentin to calcium-channel α2δ-1-subunit but does not interact with α2δ-1 on the cell-surface when co-expressed. Sci Rep 2016; 6:24531. [PMID: 27076051 PMCID: PMC4830977 DOI: 10.1038/srep24531] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 03/30/2016] [Indexed: 01/09/2023] Open
Abstract
The α2δ proteins are auxiliary subunits of voltage-gated calcium channels, and influence their trafficking and biophysical properties. The α2δ ligand gabapentin interacts with α2δ-1, and inhibits calcium channel trafficking. However, α2-1 has also been proposed to play a synaptogenic role, independent of calcium channel function. In this regard, α2δ-1 was identified as a ligand of thrombospondins, with the interaction involving the thrombospondin synaptogenic domain and the α2δ-1 von-Willebrand-factor domain. Co-immunoprecipitation between α2δ-1 and the synaptogenic domain of thrombospondin-2 was prevented by gabapentin. We therefore examined whether interaction of thrombospondin with α2δ-1 might reciprocally influence (3)H-gabapentin binding. We concentrated on thrombospondin-4, because, like α2δ-1, it is upregulated in neuropathic pain models. We found that in membranes from cells co-transfected with α2δ-1 and thrombospondin-4, there was a Mg(2+) -dependent reduction in affinity of (3)H-gabapentin binding to α2δ-1. This effect was lost for α2δ-1 with mutations in the von-Willebrand-factor-A domain. However, the effect on (3)H-gabapentin binding was not reproduced by the synaptogenic EGF-domain of thrombospondin-4. Partial co-immunoprecipitation could be demonstrated between thrombospondin-4 and α2δ-1 when co-transfected, but there was no co-immunoprecipitation with thrombospondin-4-EGF domain. Furthermore, we could not detect any association between these two proteins on the cell-surface, indicating the demonstrated interaction occurs intracellularly.
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Affiliation(s)
- Beatrice Lana
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Karen M Page
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Ivan Kadurin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Shuxian Ho
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Manuela Nieto-Rostro
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
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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: 684] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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.)
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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: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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.
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Nieto-Rostro M, Sandhu G, Bauer CS, Jiruska P, Jefferys JGR, Dolphin AC. Altered expression of the voltage-gated calcium channel subunit α₂δ-1: a comparison between two experimental models of epilepsy and a sensory nerve ligation model of neuropathic pain. Neuroscience 2014; 283:124-37. [PMID: 24641886 PMCID: PMC4259901 DOI: 10.1016/j.neuroscience.2014.03.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 03/03/2014] [Accepted: 03/09/2014] [Indexed: 12/20/2022]
Abstract
The auxiliary α2δ-1 subunit of voltage-gated calcium channels is up-regulated in dorsal root ganglion neurons following peripheral somatosensory nerve damage, in several animal models of neuropathic pain. The α2δ-1 protein has a mainly presynaptic localization, where it is associated with the calcium channels involved in neurotransmitter release. Relevant to the present study, α2δ-1 has been shown to be the therapeutic target of the gabapentinoid drugs in their alleviation of neuropathic pain. These drugs are also used in the treatment of certain epilepsies. In this study we therefore examined whether the level or distribution of α2δ-1 was altered in the hippocampus following experimental induction of epileptic seizures in rats, using both the kainic acid model of human temporal lobe epilepsy, in which status epilepticus is induced, and the tetanus toxin model in which status epilepticus is not involved. The main finding of this study is that we did not identify somatic overexpression of α2δ-1 in hippocampal neurons in either of the epilepsy models, unlike the upregulation of α2δ-1 that occurs following peripheral nerve damage to both somatosensory and motor neurons. However, we did observe local reorganization of α2δ-1 immunostaining in the hippocampus only in the kainic acid model, where it was associated with areas of neuronal cell loss, as indicated by absence of NeuN immunostaining, dendritic loss, as identified by areas where microtubule-associated protein-2 immunostaining was missing, and reactive gliosis, determined by regions of strong OX42 staining.
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Affiliation(s)
- M Nieto-Rostro
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - G Sandhu
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - C S Bauer
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - P Jiruska
- Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK
| | - J G R Jefferys
- Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK
| | - A C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK.
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Heblich F, Tran-Van-Minh A, Hendrich J, Watschinger K, Dolphin AC. Time course and specificity of the pharmacological disruption of the trafficking of voltage-gated calcium channels by gabapentin. Channels (Austin) 2014; 2:4-9. [DOI: 10.4161/chan.2.1.6045] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, McGrath JC, Catterall WA, Spedding M, Peters JA, Harmar AJ, Abul-Hasn N, Anderson CM, Anderson CMH, Araiksinen MS, Arita M, Arthofer E, Barker EL, Barratt C, Barnes NM, Bathgate R, Beart PM, Belelli D, Bennett AJ, Birdsall NJM, Boison D, Bonner TI, Brailsford L, Bröer S, Brown P, Calo G, Carter WG, Catterall WA, Chan SLF, Chao MV, Chiang N, Christopoulos A, Chun JJ, Cidlowski J, Clapham DE, Cockcroft S, Connor MA, Cox HM, Cuthbert A, Dautzenberg FM, Davenport AP, Dawson PA, Dent G, Dijksterhuis JP, Dollery CT, Dolphin AC, Donowitz M, Dubocovich ML, Eiden L, Eidne K, Evans BA, Fabbro D, Fahlke C, Farndale R, Fitzgerald GA, Fong TM, Fowler CJ, Fry JR, Funk CD, Futerman AH, Ganapathy V, Gaisnier B, Gershengorn MA, Goldin A, Goldman ID, Gundlach AL, Hagenbuch B, Hales TG, Hammond JR, Hamon M, Hancox JC, Hauger RL, Hay DL, Hobbs AJ, Hollenberg MD, Holliday ND, Hoyer D, Hynes NA, Inui KI, Ishii S, Jacobson KA, Jarvis GE, Jarvis MF, Jensen R, Jones CE, Jones RL, Kaibuchi K, Kanai Y, Kennedy C, Kerr ID, Khan AA, Klienz MJ, Kukkonen JP, Lapoint JY, Leurs R, Lingueglia E, Lippiat J, Lolait SJ, Lummis SCR, Lynch JW, MacEwan D, Maguire JJ, Marshall IL, May JM, McArdle CA, McGrath JC, Michel MC, Millar NS, Miller LJ, Mitolo V, Monk PN, Moore PK, Moorhouse AJ, Mouillac B, Murphy PM, Neubig RR, Neumaier J, Niesler B, Obaidat A, Offermanns S, Ohlstein E, Panaro MA, Parsons S, Pwrtwee RG, Petersen J, Pin JP, Poyner DR, Prigent S, Prossnitz ER, Pyne NJ, Pyne S, Quigley JG, Ramachandran R, Richelson EL, Roberts RE, Roskoski R, Ross RA, Roth M, Rudnick G, Ryan RM, Said SI, Schild L, Sanger GJ, Scholich K, Schousboe A, Schulte G, Schulz S, Serhan CN, Sexton PM, Sibley DR, Siegel JM, Singh G, Sitsapesan R, Smart TG, Smith DM, Soga T, Stahl A, Stewart G, Stoddart LA, Summers RJ, Thorens B, Thwaites DT, Toll L, Traynor JR, Usdin TB, Vandenberg RJ, Villalon C, Vore M, Waldman SA, Ward DT, Willars GB, Wonnacott SJ, Wright E, Ye RD, Yonezawa A, Zimmermann M. The Concise Guide to PHARMACOLOGY 2013/14: overview. Br J Pharmacol 2014; 170:1449-58. [PMID: 24528237 DOI: 10.1111/bph.12444] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties from the IUPHAR database. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. This compilation of the major pharmacological targets is divided into seven areas of focus: G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors & Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and GRAC and provides a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen P H Alexander
- School of Life Sciences, University of Nottingham Medical School, Nottingham, NG7 2UH, UK
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Dolphin AC. Regulation of Voltage-Gated Calcium Channel Trafficking and Function by Auxiliary Subunits. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Cassidy JS, Dolphin AC. Using Exofacially Tagged Functional Cav2.2 to Investigate the Modulation of Pore Subunit Trafficking by Auxiliary Calcium Channel Subunits. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1894] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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41
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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.
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Azizan EAB, Poulsen H, Tuluc P, Zhou J, Clausen MV, Lieb A, Maniero C, Garg S, Bochukova EG, Zhao W, Shaikh LH, Brighton CA, Teo AED, Davenport AP, Dekkers T, Tops B, Küsters B, Ceral J, Yeo GSH, Neogi SG, McFarlane I, Rosenfeld N, Marass F, Hadfield J, Margas W, Chaggar K, Solar M, Deinum J, Dolphin AC, Farooqi IS, Striessnig J, Nissen P, Brown MJ. Somatic mutations in ATP1A1 and CACNA1D underlie a common subtype of adrenal hypertension. Nat Genet 2013; 45:1055-60. [PMID: 23913004 DOI: 10.1038/ng.2716] [Citation(s) in RCA: 370] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 07/03/2013] [Indexed: 01/18/2023]
Abstract
At least 5% of individuals with hypertension have adrenal aldosterone-producing adenomas (APAs). Gain-of-function mutations in KCNJ5 and apparent loss-of-function mutations in ATP1A1 and ATP2A3 were reported to occur in APAs. We find that KCNJ5 mutations are common in APAs resembling cortisol-secreting cells of the adrenal zona fasciculata but are absent in a subset of APAs resembling the aldosterone-secreting cells of the adrenal zona glomerulosa. We performed exome sequencing of ten zona glomerulosa-like APAs and identified nine with somatic mutations in either ATP1A1, encoding the Na(+)/K(+) ATPase α1 subunit, or CACNA1D, encoding Cav1.3. The ATP1A1 mutations all caused inward leak currents under physiological conditions, and the CACNA1D mutations induced a shift of voltage-dependent gating to more negative voltages, suppressed inactivation or increased currents. Many APAs with these mutations were <1 cm in diameter and had been overlooked on conventional adrenal imaging. Recognition of the distinct genotype and phenotype for this subset of APAs could facilitate diagnosis.
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Affiliation(s)
- Elena A B Azizan
- Clinical Pharmacology Unit, Centre for Clinical Investigation, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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Affiliation(s)
- Ivan Kadurin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.
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Hendrich J, Bauer CS, Dolphin AC. Chronic pregabalin inhibits synaptic transmission between rat dorsal root ganglion and dorsal horn neurons in culture. Channels (Austin) 2012; 6:124-32. [PMID: 22627148 PMCID: PMC3396689 DOI: 10.4161/chan.19805] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In this study, we have examined the properties of synaptic transmission between dorsal root ganglion (DRG) and dorsal horn (DH) neurons, placed in co-culture. We also examined the effect of the anti-hyperalgesic gabapentinoid drug pregabalin (PGB) at this pharmacologically relevant synapse. The main method used was electrophysiological recording of excitatory post synaptic currents (EPSCs) in DH neurons. Synaptic transmission between DRG and DH neurons was stimulated by capsaicin, which activates transient receptor potential vanilloid-1 (TRPV1) receptors on small diameter DRG neurons. Capsaicin (1 μM) application increased the frequency of EPSCs recorded in DH neurons in DRG-DH co-cultures, by about 3-fold, but had no effect on other measured properties of the EPSCs. There was also no effect of capsaicin in the absence of co-cultured DRGs. Application of PGB (100 μM) for 40–48 h caused a reduction in the capsaicin-induced increase in EPSC frequency by 57%. In contrast, brief preincubation of PGB had no significant effect on the capsaicin-induced increase in EPSC frequency. In conclusion, this study shows that PGB applied for 40–48 h, but not acute application inhibits excitatory synaptic transmission at DRG-DH synapses, in response to nociceptive stimulation, most likely by a presynaptic effect on neurotransmitter release from DRG presynaptic terminals.
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Affiliation(s)
- Janek Hendrich
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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Waithe D, Ferron L, Dolphin AC. Stargazin-related protein γ₇ is associated with signalling endosomes in superior cervical ganglion neurons and modulates neurite outgrowth. J Cell Sci 2011; 124:2049-57. [PMID: 21610096 DOI: 10.1242/jcs.084988] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The role(s) of the newly discovered stargazin-like γ-subunit proteins remains unclear; although they are now widely accepted to be transmembrane AMPA receptor regulatory proteins (TARPs), rather than Ca²⁺ channel subunits, it is possible that they have more general roles in trafficking within neurons. We previously found that γ₇ subunit is associated with vesicles when it is expressed in neurons and other cells. Here, we show that γ₇ is present mainly in retrogradely transported organelles in sympathetic neurons, where it colocalises with TrkA-YFP, and with the early endosome marker EEA1, suggesting that γ₇ localises to signalling endosomes. It was not found to colocalise with markers of the endoplasmic reticulum, mitochondria, lysosomes or late endosomes. Furthermore, knockdown of endogenous γ₇ by short hairpin RNA transfection into sympathetic neurons reduced neurite outgrowth. The same was true in the PC12 neuronal cell line, where neurite outgrowth was restored by overexpression of human γ₇. These findings open the possibility that γ₇ has an essential trafficking role in relation to neurite outgrowth as a component of endosomes involved in neurite extension and growth cone remodelling.
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Affiliation(s)
- Dominic Waithe
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
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Walsh CP, Davies A, Nieto-Rostro M, Dolphin AC, Kitmitto A. Labelling of the 3D structure of the cardiac L-type voltage-gated calcium channel. Channels (Austin) 2011; 3:387-92. [PMID: 19875947 DOI: 10.4161/chan.3.6.10225] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Voltage-gated calcium channels (VGCCs) regulate calcium influx into all excitable cells. In the heart, the main calcium channels are the L-type VGCCs (LTCCs). These are localised to the sarcolemmal membrane, and are hetero-oligomeric complexes comprised of three non-covalently associated polypeptides; alpha1 (CaV1.2), alpha2delta and beta. We recently reported the 3D structure for a monomeric form of the cardiac LTCC1 using electron microscopy and single particle analysis. We also determined the first medium/low resolution structure of a T-type voltage gated calcium channel (CaV3.1) polypeptide. We identified the transmembrane and cytoplasmic domains of the T-type channel using labelling studies to determine the position of the C-terminus. By modelling of the CaV3.1 structure (comparable at these resolutions to CaV1.2) into the cardiac LTCC volume, we were able to delineate the subunit boundaries of the cardiac LTCC, leading to a proposal for a putative orientation of the LTCC with respect to the membrane bilayer. We have now extended these studies to include labelling of the extracellular alpha2 polypeptide using affinity purified antibodies raised against the Von Willebrand Factor A (VWA) domain and calmodulin-gold labelling of the C-terminus of CaV1.2. These data provide further support for the proposed orientation of the 3D structure of the cardiac LTCC.
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Affiliation(s)
- Conor P Walsh
- Cardiovascular Medicine, School of Clinical & Laboratory Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK
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Waithe D, Ferron L, Page KM, Chaggar K, Dolphin AC. Beta-subunits promote the expression of Ca(V)2.2 channels by reducing their proteasomal degradation. J Biol Chem 2011; 286:9598-611. [PMID: 21233207 PMCID: PMC3059031 DOI: 10.1074/jbc.m110.195909] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 12/22/2010] [Indexed: 02/03/2023] Open
Abstract
The β-subunits of voltage-gated calcium channels regulate their functional expression and properties. Two mechanisms have been proposed for this, an effect on gating and an enhancement of expression. With respect to the effect on expression, β-subunits have been suggested to enhance trafficking by masking an unidentified endoplasmic reticulum (ER) retention signal. Here we have investigated whether, and how, β-subunits affect the level of Ca(V)2.2 channels within somata and neurites of cultured sympathetic neurons. We have used YFP-Ca(V)2.2 containing a mutation (W391A), that prevents binding of β-subunits to its I-II linker and found that expression of this channel was much reduced compared with WT CFP-Ca(V)2.2 when both were expressed in the same neuron. This effect was particularly evident in neurites and growth cones. The difference between the levels of YFP-Ca(V)2.2(W391A) and CFP-Ca(V)2.2(WT) was lost in the absence of co-expressed β-subunits. Furthermore, the relative reduction of expression of Ca(V)2.2(W391A) compared with the WT channel was reversed by exposure to two proteasome inhibitors, MG132 and lactacystin, particularly in the somata. In further experiments in tsA-201 cells, we found that proteasome inhibition did not augment the cell surface Ca(V)2.2(W391A) level but resulted in the observation of increased ubiquitination, particularly of mutant channels. In contrast, we found no evidence for selective retention of Ca(V)2.2(W391A) in the ER, in either the soma or growth cones. In conclusion, there is a marked effect of β-subunits on Ca(V)2.2 expression, particularly in neurites, but our results point to protection from proteasomal degradation rather than masking of an ER retention signal.
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Affiliation(s)
- Dominic Waithe
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Laurent Ferron
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Karen M. Page
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Kanchan Chaggar
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Annette C. Dolphin
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
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50
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Bauer CS, Tran-Van-Minh A, Kadurin I, Dolphin AC. A new look at calcium channel α2δ subunits. Curr Opin Neurobiol 2010; 20:563-71. [PMID: 20579869 DOI: 10.1016/j.conb.2010.05.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 05/21/2010] [Accepted: 05/25/2010] [Indexed: 12/17/2022]
Abstract
The classical roles of α(2)δ proteins are as accessory calcium channel subunits, enhancing channel trafficking. They were thought to have type-I transmembrane topology, but we find that they can form GPI-anchored proteins. Moreover α(2)δ-1 and α(2)δ-3 have been shown to have novel functions in synaptogenesis, independent of their effect on calcium channels. In neurons, the α(2)δ-1 subunits are present mainly in presynaptic terminals. Peripheral sensory nerve injury results in the up-regulation of α(2)δ-1 in dorsal root ganglion (DRG) neurons, and there is a consequent increase in trafficking of α(2)δ-1 to their terminals. Furthermore, gabapentinoid drugs, which bind to α(2)δ-1 and α(2)δ-2, not only impair their trafficking, but also affect α(2)δ-1-dependent synaptogenesis. These drugs may interfere with α(2)δ function at several different levels.
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Affiliation(s)
- Claudia S Bauer
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
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