1
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Chichorro JG, Gambeta E, Baggio DF, Zamponi GW. Voltage-gated Calcium Channels as Potential Therapeutic Targets in Migraine. THE JOURNAL OF PAIN 2024; 25:104514. [PMID: 38522594 DOI: 10.1016/j.jpain.2024.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 03/06/2024] [Accepted: 03/12/2024] [Indexed: 03/26/2024]
Abstract
Migraine is a complex and highly incapacitating neurological disorder that affects around 15% of the general population with greater incidence in women, often at the most productive age of life. Migraine physiopathology is still not fully understood, but it involves multiple mediators and events in the trigeminovascular system and the central nervous system. The identification of calcitonin gene-related peptide as a key mediator in migraine physiopathology has led to the development of effective and highly selective antimigraine therapies. However, this treatment is neither accessible nor effective for all migraine sufferers. Thus, a better understanding of migraine mechanisms and the identification of potential targets are still clearly warranted. Voltage-gated calcium channels (VGCCs) are widely distributed in the trigeminovascular system, and there is accumulating evidence of their contribution to the mechanisms associated with headache pain. Several drugs used in migraine abortive or prophylactic treatment target VGCCs, which probably contributes to their analgesic effect. This review aims to summarize the current evidence of VGGC contribution to migraine physiopathology and to discuss how current pharmacological options for migraine treatment interfere with VGGC function. PERSPECTIVE: Calcitonin gene-related peptide (CGRP) represents a major migraine mediator, but few studies have investigated the relationship between CGRP and VGCCs. CGRP release is calcium channel-dependent and VGGCs are key players in familial migraine. Further studies are needed to determine whether VGCCs are suitable molecular targets for treating migraine.
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Affiliation(s)
- Juliana G Chichorro
- Biological Sciences Sector, Department of Pharmacology, Federal University of Parana, Curitiba, Parana, Brazil.
| | - Eder Gambeta
- Cumming School of Medicine, Department of Clinical Neuroscience, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Darciane F Baggio
- Biological Sciences Sector, Department of Pharmacology, Federal University of Parana, Curitiba, Parana, Brazil
| | - Gerald W Zamponi
- Cumming School of Medicine, Department of Clinical Neuroscience, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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2
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Chin M, Kaeser PS. The intracellular C-terminus confers compartment-specific targeting of voltage-gated calcium channels. Cell Rep 2024; 43:114428. [PMID: 38996073 DOI: 10.1016/j.celrep.2024.114428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 06/07/2024] [Accepted: 06/18/2024] [Indexed: 07/14/2024] Open
Abstract
To achieve the functional polarization that underlies brain computation, neurons sort protein material into distinct compartments. Ion channel composition, for example, differs between axons and dendrites, but the molecular determinants for their polarized trafficking remain obscure. Here, we identify mechanisms that target voltage-gated Ca2+ channels (CaVs) to distinct subcellular compartments. In hippocampal neurons, CaV2s trigger neurotransmitter release at the presynaptic active zone, and CaV1s localize somatodendritically. After knockout of all three CaV2s, expression of CaV2.1, but not CaV1.3, restores neurotransmitter release. We find that chimeric CaV1.3s with CaV2.1 intracellular C-termini localize to the active zone, mediate synaptic vesicle exocytosis, and render release sensitive to CaV1 blockers. This dominant targeting function of the CaV2.1 C-terminus requires the first EF hand in its proximal segment, and replacement of the CaV2.1 C-terminus with that of CaV1.3 abolishes CaV2.1 active zone localization and function. We conclude that CaV intracellular C-termini mediate compartment-specific targeting.
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Affiliation(s)
- Morven Chin
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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3
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Li J, Veeraraghavan P, Young SM. Ca V 2.1 α 1 subunit motifs that control presynaptic Ca V 2.1 subtype abundance are distinct from Ca V 2.1 preference. J Physiol 2024; 602:485-506. [PMID: 38155373 PMCID: PMC10872416 DOI: 10.1113/jp284957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 11/30/2023] [Indexed: 12/30/2023] Open
Abstract
Presynaptic voltage-gated Ca2+ channel (CaV ) subtype abundance at mammalian synapses regulates synaptic transmission in health and disease. In the mammalian central nervous system (CNS), most presynaptic terminals are CaV 2.1 dominant with a developmental reduction in CaV 2.2 and CaV 2.3 levels, and CaV 2 subtype levels are altered in various diseases. However, the molecular mechanisms controlling presynaptic CaV 2 subtype levels are largely unsolved. Because the CaV 2 α1 subunit cytoplasmic regions contain varying levels of sequence conservation, these regions are proposed to control presynaptic CaV 2 subtype preference and abundance. To investigate the potential role of these regions, we expressed chimeric CaV 2.1 α1 subunits containing swapped motifs with the CaV 2.2 and CaV 2.3 α1 subunit on a CaV 2.1/CaV 2.2 null background at the calyx of Held presynaptic terminals. We found that expression of CaV 2.1 α1 subunit chimeras containing the CaV 2.3 loop II-III region or cytoplasmic C-terminus (CT) resulted in a large reduction of presynaptic Ca2+ currents compared to the CaV 2.1 α1 subunit. However, the Ca2+ current sensitivity to the CaV 2.1 blocker agatoxin-IVA was the same between the chimeras and the CaV 2.1 α1 subunit. Additionally, we found no reduction in presynaptic Ca2+ currents with CaV 2.1/2.2 cytoplasmic CT chimeras. We conclude that the motifs in the CaV 2.1 loop II-III and CT do not individually regulate CaV 2.1 preference, although these motifs control CaV 2.1 levels and the CaV 2.3 CT contains motifs that negatively regulate presynaptic CaV 2.3 levels. We propose that the motifs controlling presynaptic CaV 2.1 preference are distinct from those regulating CaV 2.1 levels and may act synergistically to impact pathways regulating CaV 2.1 preference and abundance. KEY POINTS: Presynaptic CaV 2 subtype abundance regulates neuronal circuit properties, although the mechanisms regulating presynaptic CaV 2 subtype abundance and preference remain enigmatic. The CaV α1 subunit determines subtype and contains multiple motifs implicated in regulating presynaptic subtype abundance and preference. The CaV 2.1 α1 subunit domain II-III loop and cytoplasmic C-terminus are positive regulators of presynaptic CaV 2.1 abundance but do not regulate preference. The CaV 2.3 α1 subunit cytoplasmic C-terminus negatively regulates presynaptic CaV 2 subtype abundance but not preference, whereas the CaV 2.2 α1 subunit cytoplasmic C-terminus is not a key regulator of presynaptic CaV 2 subtype abundance or preference. The CaV 2 α1 subunit motifs determining the presynaptic CaV 2 preference are distinct from abundance.
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Affiliation(s)
- Jianing Li
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA, USA
- Cell Developmental Biology Graduate Program, University of Iowa, Iowa City, IA 52242, USA
| | | | - Samuel M. Young
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA, USA
- Department of Otolaryngology, Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA
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4
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Chin M, Kaeser PS. The intracellular C-terminus confers compartment-specific targeting of voltage-gated Ca 2+ channels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.23.573183. [PMID: 38187530 PMCID: PMC10769351 DOI: 10.1101/2023.12.23.573183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
To achieve the functional polarization that underlies brain computation, neurons sort protein material into distinct compartments. Ion channel composition, for example, differs between axons and dendrites, but the molecular determinants for their polarized trafficking remain obscure. Here, we identify the mechanisms that target voltage-gated Ca2+ channels (CaVs) to distinct subcellular compartments. In hippocampal neurons, CaV2s trigger neurotransmitter release at the presynaptic active zone, and CaV1s localize somatodendritically. After knockout of all three CaV2s, expression of CaV2.1, but not of CaV1.3, restores neurotransmitter release. Chimeric CaV1.3 channels with CaV2.1 intracellular C-termini localize to the active zone, mediate synaptic vesicle exocytosis, and render release fully sensitive to blockade of CaV1 channels. This dominant targeting function of the CaV2.1 C-terminus requires an EF hand in its proximal segment, and replacement of the CaV2.1 C-terminus with that of CaV1.3 abolishes CaV2.1 active zone localization. We conclude that the intracellular C-termini mediate compartment-specific CaV targeting.
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Affiliation(s)
- Morven Chin
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Pascal S. Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
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5
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Li J, Veeraraghavan P, Young SM. CaV2.1 α1 subunit motifs that control presynaptic CaV2.1 subtype abundance are distinct from CaV2.1 preference. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.28.538778. [PMID: 37162941 PMCID: PMC10168310 DOI: 10.1101/2023.04.28.538778] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Presynaptic voltage-gated Ca2+ channels (CaV) subtype abundance at mammalian synapses regulates synaptic transmission in health and disease. In the mammalian central nervous system, most presynaptic terminals are CaV2.1 dominant with a developmental reduction in CaV2.2 and CaV2.3 levels, and CaV2 subtype levels are altered in various diseases. However, the molecular mechanisms controlling presynaptic CaV2 subtype levels are largely unsolved. Since the CaV2 α1 subunit cytoplasmic regions contain varying levels of sequence conservation, these regions are proposed to control presynaptic CaV2 subtype preference and abundance. To investigate the potential role of these regions, we expressed chimeric CaV2.1 α1subunits containing swapped motifs with the CaV2.2 and CaV2.3 α1 subunit on a CaV2.1/CaV2.2 null background at the calyx of Held presynaptic terminal. We found that expression of CaV2.1 α1 subunit chimeras containing the CaV2.3 loop II-III region or cytoplasmic C-terminus (CT) resulted in a large reduction of presynaptic Ca2+ currents compared to the CaV2.1 α1 subunit. However, the Ca2+ current sensitivity to the CaV2.1 blocker Agatoxin-IVA, was the same between the chimeras and the CaV2.1 α1 subunit. Additionally, we found no reduction in presynaptic Ca2+ currents with CaV2.1/2.2 cytoplasmic CT chimeras. We conclude that the motifs in the CaV2.1 loop II-III and CT do not individually regulate CaV2.1 preference, but these motifs control CaV2.1 levels and the CaV2.3 CT contains motifs that negatively regulate presynaptic CaV2.3 levels. We propose that the motifs controlling presynaptic CaV2.1 preference are distinct from those regulating CaV2.1 levels and may act synergistically to impact pathways regulating CaV2.1 preference and abundance.
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Cingolani LA, Thalhammer A, Jaudon F, Muià J, Baj G. Nanoscale organization of Ca V2.1 splice isoforms at presynaptic terminals: implications for synaptic vesicle release and synaptic facilitation. Biol Chem 2023; 404:931-937. [PMID: 37658578 PMCID: PMC10695435 DOI: 10.1515/hsz-2023-0235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/01/2023] [Indexed: 09/03/2023]
Abstract
The distance between CaV2.1 voltage-gated Ca2+ channels and the Ca2+ sensor responsible for vesicle release at presynaptic terminals is critical for determining synaptic strength. Yet, the molecular mechanisms responsible for a loose coupling configuration of CaV2.1 in certain synapses or developmental periods and a tight one in others remain unknown. Here, we examine the nanoscale organization of two CaV2.1 splice isoforms (CaV2.1[EFa] and CaV2.1[EFb]) at presynaptic terminals by superresolution structured illumination microscopy. We find that CaV2.1[EFa] is more tightly co-localized with presynaptic markers than CaV2.1[EFb], suggesting that alternative splicing plays a crucial role in the synaptic organization of CaV2.1 channels.
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Affiliation(s)
- Lorenzo A. Cingolani
- Department of Life Sciences, University of Trieste, via Giorgieri 5, I-34127Trieste, Italy
- Center for Synaptic Neuroscience and Technology (NSYN), Fondazione Istituto Italiano di Tecnologia (IIT), Largo Rosanna Benzi 10, I-16132Genoa, Italy
| | - Agnes Thalhammer
- Department of Life Sciences, University of Trieste, via Giorgieri 5, I-34127Trieste, Italy
- Centro Interdipartimentale di Microscopia Avanzata (CIMA), University of Trieste, via Fleming 31, I-34127Trieste, Italy
| | - Fanny Jaudon
- Department of Life Sciences, University of Trieste, via Giorgieri 5, I-34127Trieste, Italy
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, I-16132Genoa, Italy
| | - Jessica Muià
- Department of Life Sciences, University of Trieste, via Giorgieri 5, I-34127Trieste, Italy
| | - Gabriele Baj
- Department of Life Sciences, University of Trieste, via Giorgieri 5, I-34127Trieste, Italy
- Centro Interdipartimentale di Microscopia Avanzata (CIMA), University of Trieste, via Fleming 31, I-34127Trieste, Italy
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7
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Folacci M, Estaran S, Ménard C, Bertaud A, Rousset M, Roussel J, Thibaud JB, Vignes M, Chavanieu A, Charnet P, Cens T. Functional Characterization of Four Known Cav2.1 Variants Associated with Neurodevelopmental Disorders. MEMBRANES 2023; 13:96. [PMID: 36676903 PMCID: PMC9864995 DOI: 10.3390/membranes13010096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/06/2023] [Accepted: 01/09/2023] [Indexed: 06/17/2023]
Abstract
Cav2.1 channels are expressed throughout the brain and are the predominant Ca2+ channels in the Purkinje cells. These cerebellar neurons fire spontaneously, and Cav2.1 channels are involved in the regular pacemaking activity. The loss of precision of the firing pattern of Purkinje cells leads to ataxia, a disorder characterized by poor balance and difficulties in performing coordinated movements. In this study, we aimed at characterizing functional and structural consequences of four variations (p.A405T in I-II loop and p.R1359W, p.R1667W and p.S1799L in IIIS4, IVS4, and IVS6 helices, respectively) identified in patients exhibiting a wide spectrum of disorders including ataxia symptoms. Functional analysis using two major Cav2.1 splice variants (Cav2.1+e47 and Cav2.1-e47) in Xenopus laevis oocytes, revealed a lack of effect upon A405T substitution and a significant loss-of-function caused by R1359W, whereas R1667W and S1799L caused both channel gain-of-function and loss-of-function, in a splice variant-dependent manner. Structural analysis revealed the loss of interactions with S1, S2, and S3 helices upon R1359W and R1667W substitutions, but a lack of obvious structural changes with S1799L. Computational modeling suggests that biophysical changes induced by Cav2.1 pathogenic mutations might affect action potential frequency in Purkinje cells.
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8
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Zong P, Yue L. Regulation of Presynaptic Calcium Channels. ADVANCES IN NEUROBIOLOGY 2023; 33:171-202. [PMID: 37615867 DOI: 10.1007/978-3-031-34229-5_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Voltage-gated calcium channels (VGCCs), especially Cav2.1 and Cav2.2, are the major mediators of Ca2+ influx at the presynaptic membrane in response to neuron excitation, thereby exerting a predominant control on synaptic transmission. To guarantee the timely and precise release of neurotransmitters at synapses, the activity of presynaptic VGCCs is tightly regulated by a variety of factors, including auxiliary subunits, membrane potential, G protein-coupled receptors (GPCRs), calmodulin (CaM), Ca2+-binding proteins (CaBP), protein kinases, various interacting proteins, alternative splicing events, and genetic variations.
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Affiliation(s)
- Pengyu Zong
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine, Farmington, CT, USA
| | - Lixia Yue
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine, Farmington, CT, USA.
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9
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Pengelly RJ, Bakhtiar D, Borovská I, Královičová J, Vořechovský I. Exonic splicing code and protein binding sites for calcium. Nucleic Acids Res 2022; 50:5493-5512. [PMID: 35474482 PMCID: PMC9177970 DOI: 10.1093/nar/gkac270] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/01/2022] [Accepted: 04/05/2022] [Indexed: 11/12/2022] Open
Abstract
Auxilliary splicing sequences in exons, known as enhancers (ESEs) and silencers (ESSs), have been subject to strong selection pressures at the RNA and protein level. The protein component of this splicing code is substantial, recently estimated at ∼50% of the total information within ESEs, but remains poorly understood. The ESE/ESS profiles were previously associated with the Irving-Williams (I-W) stability series for divalent metals, suggesting that the ESE/ESS evolution was shaped by metal binding sites. Here, we have examined splicing activities of exonic sequences that encode protein binding sites for Ca2+, a weak binder in the I-W affinity order. We found that predicted exon inclusion levels for the EF-hand motifs and for Ca2+-binding residues in nonEF-hand proteins were higher than for average exons. For canonical EF-hands, the increase was centred on the EF-hand chelation loop and, in particular, on Ca2+-coordinating residues, with a 1>12>3∼5>9 hierarchy in the 12-codon loop consensus and usage bias at codons 1 and 12. The same hierarchy but a lower increase was observed for noncanonical EF-hands, except for S100 proteins. EF-hand loops preferentially accumulated exon splits in two clusters, one located in their N-terminal halves and the other around codon 12. Using splicing assays and published crosslinking and immunoprecipitation data, we identify candidate trans-acting factors that preferentially bind conserved GA-rich motifs encoding negatively charged amino acids in the loops. Together, these data provide evidence for the high capacity of codons for Ca2+-coordinating residues to be retained in mature transcripts, facilitating their exon-level expansion during eukaryotic evolution.
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Affiliation(s)
- Reuben J Pengelly
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
| | - Dara Bakhtiar
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
| | - Ivana Borovská
- Slovak Academy of Sciences, Centre of Biosciences, 840 05 Bratislava, Slovak Republic
| | - Jana Královičová
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
- Slovak Academy of Sciences, Centre of Biosciences, 840 05 Bratislava, Slovak Republic
- Slovak Academy of Sciences, Institute of Zoology, 845 06 Bratislava, Slovak Republic
| | - Igor Vořechovský
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
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Heck J, Palmeira Do Amaral AC, Weißbach S, El Khallouqi A, Bikbaev A, Heine M. More than a pore: How voltage-gated calcium channels act on different levels of neuronal communication regulation. Channels (Austin) 2021; 15:322-338. [PMID: 34107849 PMCID: PMC8205089 DOI: 10.1080/19336950.2021.1900024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 02/06/2023] Open
Abstract
Voltage-gated calcium channels (VGCCs) represent key regulators of the calcium influx through the plasma membrane of excitable cells, like neurons. Activated by the depolarization of the membrane, the opening of VGCCs induces very transient and local changes in the intracellular calcium concentration, known as calcium nanodomains, that in turn trigger calcium-dependent signaling cascades and the release of chemical neurotransmitters. Based on their central importance as concierges of excitation-secretion coupling and therefore neuronal communication, VGCCs have been studied in multiple aspects of neuronal function and malfunction. However, studies on molecular interaction partners and recent progress in omics technologies have extended the actual concept of these molecules. With this review, we want to illustrate some new perspectives of VGCCs reaching beyond their function as calcium-permeable pores in the plasma membrane. Therefore, we will discuss the relevance of VGCCs as voltage sensors in functional complexes with ryanodine receptors, channel-independent actions of auxiliary VGCC subunits, and provide an insight into how VGCCs even directly participate in gene regulation. Furthermore, we will illustrate how structural changes in the intracellular C-terminus of VGCCs generated by alternative splicing events might not only affect the biophysical channel characteristics but rather determine their molecular environment and downstream signaling pathways.
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Affiliation(s)
- Jennifer Heck
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Ana Carolina Palmeira Do Amaral
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Stephan Weißbach
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
- Computational Genomics and Bioinformatics, Johannes Gutenberg-University Mainz, University Medical Center Mainz, Institute for Human Genetics, Mainz, Germany
| | - Abderazzaq El Khallouqi
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Arthur Bikbaev
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Martin Heine
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
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Gandini MA, Souza IA, Ferron L, Innes AM, Zamponi GW. The de novo CACNA1A pathogenic variant Y1384C associated with hemiplegic migraine, early onset cerebellar atrophy and developmental delay leads to a loss of Cav2.1 channel function. Mol Brain 2021; 14:27. [PMID: 33557884 PMCID: PMC7871581 DOI: 10.1186/s13041-021-00745-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/02/2021] [Indexed: 12/12/2022] Open
Abstract
CACNA1A pathogenic variants have been linked to several neurological disorders including familial hemiplegic migraine and cerebellar conditions. More recently, de novo variants have been associated with severe early onset developmental encephalopathies. CACNA1A is highly expressed in the central nervous system and encodes the pore-forming CaVα1 subunit of P/Q-type (Cav2.1) calcium channels. We have previously identified a patient with a de novo missense mutation in CACNA1A (p.Y1384C), characterized by hemiplegic migraine, cerebellar atrophy and developmental delay. The mutation is located at the transmembrane S5 segment of the third domain. Functional analysis in two predominant splice variants of the neuronal Cav2.1 channel showed a significant loss of function in current density and changes in gating properties. Moreover, Y1384 variants exhibit differential splice variant-specific effects on recovery from inactivation. Finally, structural analysis revealed structural damage caused by the tyrosine substitution and changes in electrostatic potentials.
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Affiliation(s)
- Maria A Gandini
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Ivana A Souza
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Laurent Ferron
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - A Micheil Innes
- Department of Medical Genetics and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
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12
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Yeow SQZ, Loh KWZ, Soong TW. Calcium Channel Splice Variants and Their Effects in Brain and Cardiovascular Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:67-86. [DOI: 10.1007/978-981-16-4254-8_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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13
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Jaudon F, Baldassari S, Musante I, Thalhammer A, Zara F, Cingolani LA. Targeting Alternative Splicing as a Potential Therapy for Episodic Ataxia Type 2. Biomedicines 2020; 8:E332. [PMID: 32899500 PMCID: PMC7555146 DOI: 10.3390/biomedicines8090332] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/01/2020] [Accepted: 09/04/2020] [Indexed: 12/26/2022] Open
Abstract
Episodic ataxia type 2 (EA2) is an autosomal dominant neurological disorder characterized by paroxysmal attacks of ataxia, vertigo, and nausea that usually last hours to days. It is caused by loss-of-function mutations in CACNA1A, the gene encoding the pore-forming α1 subunit of P/Q-type voltage-gated Ca2+ channels. Although pharmacological treatments, such as acetazolamide and 4-aminopyridine, exist for EA2, they do not reduce or control the symptoms in all patients. CACNA1A is heavily spliced and some of the identified EA2 mutations are predicted to disrupt selective isoforms of this gene. Modulating splicing of CACNA1A may therefore represent a promising new strategy to develop improved EA2 therapies. Because RNA splicing is dysregulated in many other genetic diseases, several tools, such as antisense oligonucleotides, trans-splicing, and CRISPR-based strategies, have been developed for medical purposes. Here, we review splicing-based strategies used for genetic disorders, including those for Duchenne muscular dystrophy, spinal muscular dystrophy, and frontotemporal dementia with Parkinsonism linked to chromosome 17, and discuss their potential applicability to EA2.
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Affiliation(s)
- Fanny Jaudon
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy;
| | - Simona Baldassari
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (S.B.); (I.M.); (F.Z.)
| | - Ilaria Musante
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (S.B.); (I.M.); (F.Z.)
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, 16126 Genoa, Italy
| | - Agnes Thalhammer
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), 16132 Genoa, Italy;
- IRCCS Ospedale Policlinico San Martino, 16132 Genoa, Italy
| | - Federico Zara
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (S.B.); (I.M.); (F.Z.)
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, 16126 Genoa, Italy
| | - Lorenzo A. Cingolani
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy;
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), 16132 Genoa, Italy;
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14
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Thalhammer A, Jaudon F, Cingolani LA. Emerging Roles of Activity-Dependent Alternative Splicing in Homeostatic Plasticity. Front Cell Neurosci 2020; 14:104. [PMID: 32477067 PMCID: PMC7235277 DOI: 10.3389/fncel.2020.00104] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 04/06/2020] [Indexed: 12/25/2022] Open
Abstract
Homeostatic plasticity refers to the ability of neuronal networks to stabilize their activity in the face of external perturbations. Most forms of homeostatic plasticity ultimately depend on changes in the expression or activity of ion channels and synaptic proteins, which may occur at the gene, transcript, or protein level. The most extensively investigated homeostatic mechanisms entail adaptations in protein function or localization following activity-dependent posttranslational modifications. Numerous studies have also highlighted how homeostatic plasticity can be achieved by adjusting local protein translation at synapses or transcription of specific genes in the nucleus. In comparison, little attention has been devoted to whether and how alternative splicing (AS) of pre-mRNAs underlies some forms of homeostatic plasticity. AS not only expands proteome diversity but also contributes to the spatiotemporal dynamics of mRNA transcripts. Prominent in the brain where it can be regulated by neuronal activity, it is a flexible process, tightly controlled by a multitude of factors. Given its extensive use and versatility in optimizing the function of ion channels and synaptic proteins, we argue that AS is ideally suited to achieve homeostatic control of neuronal output. We support this thesis by reviewing emerging evidence linking AS to various forms of homeostatic plasticity: homeostatic intrinsic plasticity, synaptic scaling, and presynaptic homeostatic plasticity. Further, we highlight the relevance of this connection for brain pathologies.
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Affiliation(s)
- Agnes Thalhammer
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Fanny Jaudon
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Lorenzo A Cingolani
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Genoa, Italy.,Department of Life Sciences, University of Trieste, Trieste, Italy
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15
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Brockhaus J, Brüggen B, Missler M. Imaging and Analysis of Presynaptic Calcium Influx in Cultured Neurons Using synGCaMP6f. Front Synaptic Neurosci 2019; 11:12. [PMID: 31057389 PMCID: PMC6477507 DOI: 10.3389/fnsyn.2019.00012] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 03/26/2019] [Indexed: 12/12/2022] Open
Abstract
Presynaptic Ca2+ influx through voltage-gated calcium channels (VGCCs) is a key step in synaptic transmission that links action potential (AP)-derived depolarization to vesicle release. However, investigation of presynaptic Ca2+ influx by patch clamp recordings is difficult due to the small size of the majority of synaptic boutons along thin axons that hamper clamp control. Genetically encoded calcium indicators (GECIs) in combination with live cell imaging provide an alternative method to study Ca2+ transients in individual presynaptic terminals. The indicator GCaMP6f was developed for fast speed and high sensitivity in detecting Ca2+ transients even in subcellular compartments. We fused GCaMP6f to synaptophysin (synGCaMP6f) to enrich the calcium indicator in presynaptic boutons of transfected primary hippocampal neurons to study presynaptic Ca2+ changes in response to individual APs or short bursts. Changes in fluorescence intensity were evaluated by normalization to control level or, alternatively, by normalization to maximal fluorescence using the calcium ionophore ionomycin. Measurements revealed robust Ca2+ transients with amplitudes that depend on parameters like the number of APs, stimulation frequency or external calcium concentration. Our findings indicate an appropriate sensitivity of synGCaMP6f for studying total presynaptic Ca2+ transients induced by single APs or short bursts that showed little rundown of the response after repeated bursts. Moreover, these recordings are fast enough to even study short-term plasticity like paired pulse facilitation (PPF) and frequency dependence of Ca2+ transients. In addition, synGCaMP6f could be used to dissect the contribution of different subtypes of VGCCs to presynaptic Ca2+ influx. Our results demonstrate that synGCaMP6f allows the reliable analysis of changes in presynaptic calcium concentration at many individual synaptic boutons in parallel and provides the possibility to study the regulation of this important step in synaptic transmission.
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Affiliation(s)
- Johannes Brockhaus
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Münster, Germany
| | - Bianca Brüggen
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Münster, Germany
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Münster, Germany
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16
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Ca 2+-dependent regulation of sodium channels Na V1.4 and Na V1.5 is controlled by the post-IQ motif. Nat Commun 2019; 10:1514. [PMID: 30944319 PMCID: PMC6447637 DOI: 10.1038/s41467-019-09570-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 03/12/2019] [Indexed: 01/01/2023] Open
Abstract
Skeletal muscle voltage-gated Na+ channel (NaV1.4) activity is subject to calmodulin (CaM) mediated Ca2+-dependent inactivation; no such inactivation is observed in the cardiac Na+ channel (NaV1.5). Taken together, the crystal structures of the NaV1.4 C-terminal domain relevant complexes and thermodynamic binding data presented here provide a rationale for this isoform difference. A Ca2+-dependent CaM N-lobe binding site previously identified in NaV1.5 is not present in NaV1.4 allowing the N-lobe to signal other regions of the NaV1.4 channel. Consistent with this mechanism, removing this binding site in NaV1.5 unveils robust Ca2+-dependent inactivation in the previously insensitive isoform. These findings suggest that Ca2+-dependent inactivation is effected by CaM's N-lobe binding outside the NaV C-terminal while CaM's C-lobe remains bound to the NaV C-terminal. As the N-lobe binding motif of NaV1.5 is a mutational hotspot for inherited arrhythmias, the contributions of mutation-induced changes in CDI to arrhythmia generation is an intriguing possibility.
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17
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Williams B, Haeseleer F, Lee A. Splicing of an automodulatory domain in Ca v1.4 Ca 2+ channels confers distinct regulation by calmodulin. J Gen Physiol 2018; 150:1676-1687. [PMID: 30355583 PMCID: PMC6279360 DOI: 10.1085/jgp.201812140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 10/03/2018] [Indexed: 12/17/2022] Open
Abstract
Cav1.4 Ca2+ channels provide maintained Ca2+ entry to support sustained neurotransmitter release, but a retinal splice variant exhibits calmodulin-dependent inactivation. Williams et al. show that the N lobe of calmodulin is involved in this process as well as Ca2+-dependent enhancement of channel activation. Ca2+ influx through Cav1.4 L-type Ca2+ channels supports the sustained release of glutamate from photoreceptor synaptic terminals in darkness, a process that is critical for vision. Consistent with this role, Cav1.4 exhibits weak Ca2+-dependent inactivation (CDI)—a negative feedback regulation mediated by Ca2+-bound calmodulin (CaM). CaM binds to a conserved IQ domain in the proximal C-terminal domain of Cav channels, but in Cav1.4, a C-terminal modulatory domain (CTM) disrupts interactions with CaM. Exon 47 encodes a portion of the CTM and is deleted in a Cav1.4 splice variant (Cav1.4Δex47) that is highly expressed in the human retina. Cav1.4Δex47 exhibits CDI and enhanced voltage-dependent activation, similar to that caused by a mutation that is associated with congenital stationary night blindness type 2, in which the CTM is deleted (K1591X). The presence of CDI and very negative activation thresholds in a naturally occurring variant of Cav1.4 are perplexing considering that these properties are expected to be maladaptive for visual signaling and result in night blindness in the case of K1591X. Here we show that Cav1.4Δex47 and K1591X exhibit fundamental differences in their regulation by CaM. In Cav1.4Δex47, CDI requires both the N-terminal (N lobe) and C-terminal (C lobe) lobes of CaM to bind Ca2+, whereas CDI in K1591X is driven mainly by Ca2+ binding to the C lobe. Moreover, the CaM N lobe causes a Ca2+-dependent enhancement of activation of Cav1.4Δex47 but not K1591X. We conclude that the residual CTM in Cav1.4Δex47 enables a form of CaM N lobe regulation of activation and CDI that is absent in K1591X. Interaction with the N lobe of CaM, which is more sensitive to global elevations in cytosolic Ca2+ than the C lobe, may allow Cav1.4Δex47 to be modulated by a wider range of synaptic Ca2+ concentrations than K1591X; this may distinguish the normal physiological function of Cav1.4Δex47 from the pathological consequences of K1591X.
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Affiliation(s)
- Brittany Williams
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA
| | - Françoise Haeseleer
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA .,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA.,Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA.,Department of Neurology, University of Iowa, Iowa City, IA
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18
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Furlanis E, Scheiffele P. Regulation of Neuronal Differentiation, Function, and Plasticity by Alternative Splicing. Annu Rev Cell Dev Biol 2018; 34:451-469. [PMID: 30028642 DOI: 10.1146/annurev-cellbio-100617-062826] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Posttranscriptional mechanisms provide powerful means to expand the coding power of genomes. In nervous systems, alternative splicing has emerged as a fundamental mechanism not only for the diversification of protein isoforms but also for the spatiotemporal control of transcripts. Thus, alternative splicing programs play instructive roles in the development of neuronal cell type-specific properties, neuronal growth, self-recognition, synapse specification, and neuronal network function. Here we discuss the most recent genome-wide efforts on mapping RNA codes and RNA-binding proteins for neuronal alternative splicing regulation. We illustrate how alternative splicing shapes key steps of neuronal development, neuronal maturation, and synaptic properties. Finally, we highlight efforts to dissect the spatiotemporal dynamics of alternative splicing and their potential contribution to neuronal plasticity and the mature nervous system.
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19
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Jeans AF, van Heusden FC, Al-Mubarak B, Padamsey Z, Emptage NJ. Homeostatic Presynaptic Plasticity Is Specifically Regulated by P/Q-type Ca 2+ Channels at Mammalian Hippocampal Synapses. Cell Rep 2018; 21:341-350. [PMID: 29020622 PMCID: PMC5643522 DOI: 10.1016/j.celrep.2017.09.061] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 08/11/2017] [Accepted: 09/19/2017] [Indexed: 11/17/2022] Open
Abstract
Voltage-dependent Ca2+ channels (VGCC) represent the principal source of Ca2+ ions driving evoked neurotransmitter release at presynaptic boutons. In mammals, presynaptic Ca2+ influx is mediated mainly via P/Q-type and N-type VGCC, which differ in their properties. Changes in their relative contributions tune neurotransmission both during development and in Hebbian plasticity. However, whether this represents a functional motif also present in other forms of activity-dependent regulation is unknown. Here, we study the role of VGCC in homeostatic plasticity (HSP) in mammalian hippocampal neurons using optical techniques. We find that changes in evoked Ca2+ currents specifically through P/Q-type, but not N-type, VGCC mediate bidirectional homeostatic regulation of both neurotransmitter release efficacy and the size of the major synaptic vesicle pools. Selective dependence of HSP on P/Q-type VGCC in mammalian terminals has important implications for phenotypes associated with P/Q-type channelopathies, including migraine and epilepsy. P/Q-type VGCC regulate homeostatic synaptic plasticity (HSP) in mammals Changes in synaptic vesicle pool sizes during HSP are also mediated via P/Q-type VGCC Expression of HSP is independent of N-type VGCC regulation P/Q-type regulation of HSP may explain phenotypes of P/Q-type channelopathies
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Affiliation(s)
- Alexander F Jeans
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Fran C van Heusden
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Bashayer Al-Mubarak
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK; Department of Genetics, King Faisal Specialist Hospital and Research Center, PO Box 3354, Riyadh 11211, Saudi Arabia
| | - Zahid Padamsey
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Nigel J Emptage
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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20
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Thalhammer A, Contestabile A, Ermolyuk YS, Ng T, Volynski KE, Soong TW, Goda Y, Cingolani LA. Alternative Splicing of P/Q-Type Ca 2+ Channels Shapes Presynaptic Plasticity. Cell Rep 2018; 20:333-343. [PMID: 28700936 DOI: 10.1016/j.celrep.2017.06.055] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 06/04/2017] [Accepted: 06/21/2017] [Indexed: 12/26/2022] Open
Abstract
Alternative splicing of pre-mRNAs is prominent in the mammalian brain, where it is thought to expand proteome diversity. For example, alternative splicing of voltage-gated Ca2+ channel (VGCC) α1 subunits can generate thousands of isoforms with differential properties and expression patterns. However, the impact of this molecular diversity on brain function, particularly on synaptic transmission, which crucially depends on VGCCs, is unclear. Here, we investigate how two major splice isoforms of P/Q-type VGCCs (Cav2.1[EFa/b]) regulate presynaptic plasticity in hippocampal neurons. We find that the efficacy of P/Q-type VGCC isoforms in supporting synaptic transmission is markedly different, with Cav2.1[EFa] promoting synaptic depression and Cav2.1[EFb] synaptic facilitation. Following a reduction in network activity, hippocampal neurons upregulate selectively Cav2.1[EFa], the isoform exhibiting the higher synaptic efficacy, thus effectively supporting presynaptic homeostatic plasticity. Therefore, the balance between VGCC splice variants at the synapse is a key factor in controlling neurotransmitter release and presynaptic plasticity.
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Affiliation(s)
- Agnes Thalhammer
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova 16132, Italy
| | - Andrea Contestabile
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova 16163, Italy
| | | | - Teclise Ng
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456, Singapore; National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore
| | | | - Tuck Wah Soong
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456, Singapore; National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore
| | - Yukiko Goda
- RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | - Lorenzo A Cingolani
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova 16132, Italy.
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21
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Thalhammer A, Jaudon F, Cingolani LA. Combining Optogenetics with Artificial microRNAs to Characterize the Effects of Gene Knockdown on Presynaptic Function within Intact Neuronal Circuits. J Vis Exp 2018. [PMID: 29608168 PMCID: PMC5931759 DOI: 10.3791/57223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The purpose of this protocol is to characterize the effect of gene knockdown on presynaptic function within intact neuronal circuits. We describe a workflow on how to combine artificial microRNA (miR)-mediated RNA interference with optogenetics to achieve selective stimulation of manipulated presynaptic boutons in acute brain slices. The experimental approach involves the use of a single viral construct and a single neuron-specific promoter to drive the expression of both an optogenetic probe and artificial miR(s) against presynaptic gene(s). When stereotactically injected in the brain region of interest, the expressed construct makes it possible to stimulate with light exclusively the neurons with reduced expression of the gene(s) under investigation. This strategy does not require the development and maintenance of genetically modified mouse lines and can in principle be applied to other organisms and to any neuronal gene of choice. We have recently applied it to investigate how the knockdown of alternative splice isoforms of presynaptic P/Q-type voltage-gated calcium channels (VGCCs) regulates short-term synaptic plasticity at CA3 to CA1 excitatory synapses in acute hippocampal slices. A similar approach could also be used to manipulate and probe the neuronal circuitry in vivo.
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Affiliation(s)
- Agnes Thalhammer
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia
| | - Fanny Jaudon
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia
| | - Lorenzo A Cingolani
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia;
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22
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Thomas JR, Hagen J, Soh D, Lee A. Molecular moieties masking Ca 2+-dependent facilitation of voltage-gated Ca v2.2 Ca 2+ channels. J Gen Physiol 2017; 150:83-94. [PMID: 29208674 PMCID: PMC5749111 DOI: 10.1085/jgp.201711841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/29/2017] [Accepted: 10/27/2017] [Indexed: 01/08/2023] Open
Abstract
Ca2+-dependent facilitation is a positive feedback mechanism that regulates Cav2.1 P/Q-type channels but not closely related Cav2.2 N-type channels. Thomas et al. identify the molecular determinants that distinguish the ability of Cav2.1 and Cav2.2 to undergo Ca2+-dependent facilitation. Voltage-gated Cav2.1 (P/Q-type) Ca2+ channels undergo Ca2+-dependent inactivation (CDI) and facilitation (CDF), both of which contribute to short-term synaptic plasticity. Both CDI and CDF are mediated by calmodulin (CaM) binding to sites in the C-terminal domain of the Cav2.1 α1 subunit, most notably to a consensus CaM-binding IQ-like (IQ) domain. Closely related Cav2.2 (N-type) channels display CDI but not CDF, despite overall conservation of the IQ and additional sites (pre-IQ, EF-hand–like [EF] domain, and CaM-binding domain) that regulate CDF of Cav2.1. Here we investigate the molecular determinants that prevent Cav2.2 channels from undergoing CDF. Although alternative splicing of C-terminal exons regulates CDF of Cav2.1, the splicing of analogous exons in Cav2.2 does not reveal CDF. Transfer of sequences encoding the Cav2.1 EF, pre-IQ, and IQ together (EF-pre-IQ-IQ), but not individually, are sufficient to support CDF in chimeric Cav2.2 channels; Cav2.1 chimeras containing the corresponding domains of Cav2.2, either alone or together, fail to undergo CDF. In contrast to the weak binding of CaM to just the pre-IQ and IQ of Cav2.2, CaM binds to the EF-pre-IQ-IQ of Cav2.2 as well as to the corresponding domains of Cav2.1. Therefore, the lack of CDF in Cav2.2 likely arises from an inability of its EF-pre-IQ-IQ to transduce the effects of CaM rather than weak binding to CaM per se. Our results reveal a functional divergence in the CDF regulatory domains of Cav2 channels, which may help to diversify the modes by which Cav2.1 and Cav2.2 can modify synaptic transmission.
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Affiliation(s)
- Jessica R Thomas
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA
| | - Jussara Hagen
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
| | - Daniel Soh
- Medical Sciences Program, Boston University, Boston, MA
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA .,Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA.,Department of Neurology, University of Iowa, Iowa City, IA
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23
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Jackman SL, Regehr WG. The Mechanisms and Functions of Synaptic Facilitation. Neuron 2017; 94:447-464. [PMID: 28472650 DOI: 10.1016/j.neuron.2017.02.047] [Citation(s) in RCA: 224] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 02/23/2017] [Accepted: 02/28/2017] [Indexed: 12/22/2022]
Abstract
The ability of the brain to store and process information relies on changing the strength of connections between neurons. Synaptic facilitation is a form of short-term plasticity that enhances synaptic transmission for less than a second. Facilitation is a ubiquitous phenomenon thought to play critical roles in information transfer and neural processing. Yet our understanding of the function of facilitation remains largely theoretical. Here we review proposed roles for facilitation and discuss how recent progress in uncovering the underlying molecular mechanisms could enable experiments that elucidate how facilitation, and short-term plasticity in general, contributes to circuit function and animal behavior.
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Affiliation(s)
- Skyler L Jackman
- Department of Neurobiology, Harvard Medical School, Boston, MA 02118, USA
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, Boston, MA 02118, USA.
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24
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Hirano M, Takada Y, Wong CF, Yamaguchi K, Kotani H, Kurokawa T, Mori MX, Snutch TP, Ronjat M, De Waard M, Mori Y. C-terminal splice variants of P/Q-type Ca 2+ channel Ca V2.1 α 1 subunits are differentially regulated by Rab3-interacting molecule proteins. J Biol Chem 2017; 292:9365-9381. [PMID: 28377503 DOI: 10.1074/jbc.m117.778829] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 03/26/2017] [Indexed: 11/06/2022] Open
Abstract
Voltage-dependent Ca2+ channels (VDCCs) mediate neurotransmitter release controlled by presynaptic proteins such as the scaffolding proteins Rab3-interacting molecules (RIMs). RIMs confer sustained activity and anchoring of synaptic vesicles to the VDCCs. Multiple sites on the VDCC α1 and β subunits have been reported to mediate the RIMs-VDCC interaction, but their significance is unclear. Because alternative splicing of exons 44 and 47 in the P/Q-type VDCC α1 subunit CaV2.1 gene generates major variants of the CaV2.1 C-terminal region, known for associating with presynaptic proteins, we focused here on the protein regions encoded by these two exons. Co-immunoprecipitation experiments indicated that the C-terminal domain (CTD) encoded by CaV2.1 exons 40-47 interacts with the α-RIMs, RIM1α and RIM2α, and this interaction was abolished by alternative splicing that deletes the protein regions encoded by exons 44 and 47. Electrophysiological characterization of VDCC currents revealed that the suppressive effect of RIM2α on voltage-dependent inactivation (VDI) was stronger than that of RIM1α for the CaV2.1 variant containing the region encoded by exons 44 and 47. Importantly, in the CaV2.1 variant in which exons 44 and 47 were deleted, strong RIM2α-mediated VDI suppression was attenuated to a level comparable with that of RIM1α-mediated VDI suppression, which was unaffected by the exclusion of exons 44 and 47. Studies of deletion mutants of the exon 47 region identified 17 amino acid residues on the C-terminal side of a polyglutamine stretch as being essential for the potentiated VDI suppression characteristic of RIM2α. These results suggest that the interactions of the CaV2.1 CTD with RIMs enable CaV2.1 proteins to distinguish α-RIM isoforms in VDI suppression of P/Q-type VDCC currents.
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Affiliation(s)
- Mitsuru Hirano
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Yoshinori Takada
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Chee Fah Wong
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and.,the Department of Biology, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjung Malim, Perak, Malaysia
| | - Kazuma Yamaguchi
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Hiroshi Kotani
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Tatsuki Kurokawa
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Masayuki X Mori
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Terrance P Snutch
- the Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada, and
| | - Michel Ronjat
- the LabEx Ion Channels, Science and Therapeutics, INSERM UMR1087/CNRS UMR6291, Institut du Thorax, Université de Nantes, Nantes F-44000, France
| | - Michel De Waard
- the LabEx Ion Channels, Science and Therapeutics, INSERM UMR1087/CNRS UMR6291, Institut du Thorax, Université de Nantes, Nantes F-44000, France
| | - Yasuo Mori
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and .,the Department of Technology and Ecology, Hall of Global Environmental Studies, Kyoto University, Kyoto 615-8510, Japan
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25
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Lee SR, Adams PJ, Yue DT. Large Ca²⁺-dependent facilitation of Ca(V)2.1 channels revealed by Ca²⁺ photo-uncaging. J Physiol 2016; 593:2753-78. [PMID: 25809476 DOI: 10.1113/jp270091] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 03/18/2015] [Indexed: 01/30/2023] Open
Abstract
KEY POINTS CaV 2.1 channels constitute a dominant Ca(2+) entry pathway into brain neurons, triggering downstream Ca(2+) -dependent processes such as neurotransmitter release. CaV 2.1 is itself modulated by Ca(2+) , resulting in activity-dependent enhancement of channel opening termed Ca(2+) -dependent facilitation (CDF). Real-time Ca(2+) imaging and Ca(2+) uncaging here reveal that CDF turns out to be strikingly faster, more Ca(2+) sensitive, and larger than anticipated on previous grounds. Robust resolution of the quantitative profile of CDF enables deduction of a realistic biophysical model for this process. These results suggest that CaV 2.1 CDF would figure most prominently in short-term synaptic plasticity and cerebellar Purkinje cell rhythmicity. ABSTRACT CaV 2.1 (P-type) voltage-gated Ca(2+) channels constitute a major source of neuronal Ca(2+) current, strongly influencing rhythmicity and triggering neurotransmitter release throughout the central nervous system. Fitting with such stature among Ca(2+) entry pathways, CaV 2.1 is itself feedback regulated by intracellular Ca(2+) , acting through calmodulin to facilitate channel opening. The precise neurophysiological role of this calcium-dependent facilitation (CDF) remains uncertain, however, in large measure because the very magnitude, Ca(2+) dependence and kinetics of CDF have resisted quantification by conventional means. Here, we utilize the photo-uncaging of Ca(2+) with CaV 2.1 channels fluxing Li(+) currents, so that voltage-dependent activation of channel gating is no longer conflated with Ca(2+) entry, and CDF is then driven solely by light-induced increases in Ca(2+) . By using this strategy, we now find that CDF can be unexpectedly large, enhancing currents by as much as twofold at physiological voltages. CDF is steeply Ca(2+) dependent, with a Hill coefficient of approximately two, a half-maximal effect reached by nearly 500 nm Ca(2+) , and Ca(2+) on/off kinetics in the order of milliseconds to tens of milliseconds. These properties were established for both native P-type currents in cerebellar Purkinje neurons, as well as their recombinant channel counterparts under heterologous expression. Such features suggest that CDF of CaV 2.1 channels may substantially enhance the regularity of rhythmic firing in cerebellar Purkinje neurons, where regularity is believed crucial for motor coordination. In addition, this degree of extensive CDF would be poised to exert large order-of-magnitude effects on short-term synaptic plasticity via rapid modulation of presynaptic Ca(2+) entry.
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Affiliation(s)
- Shin-Rong Lee
- Calcium Signals Laboratory, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Departments of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Paul J Adams
- Department of Biology, Kwantlen Polytechnic University, Surrey, BC, Canada, V3W 2M8
| | - David T Yue
- Calcium Signals Laboratory, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Departments of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Center for Cell Dynamics, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
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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: 704] [Impact Index Per Article: 78.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.
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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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Cowles CL, Wu YY, Barnett SD, Lee MT, Burkin HR, Buxton ILO. Alternatively Spliced Human TREK-1 Variants Alter TREK-1 Channel Function and Localization. Biol Reprod 2015; 93:122. [PMID: 26400398 DOI: 10.1095/biolreprod.115.129791] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 09/14/2015] [Indexed: 11/01/2022] Open
Abstract
TREK-1, an outward-rectifying potassium channel activated by stretch, is found in the myometrium of pregnant women. Decreased expression of TREK-1 near term suggests that TREK-1 may contribute to uterine quiescence during gestation. Five alternatively spliced TREK-1 variants were identified in the myometrium of mothers who delivered spontaneously preterm (<37 wk), leading to the hypothesis that these TREK-1 variants could interfere with TREK-1 function or expression. To investigate a potential role for these variants, immunofluorescence, cell surface assays, Western blots, and patch clamp were employed to study TREK-1 and TREK-1 variants expressed in HEK293T cells. The results of this study demonstrate that coexpression of TREK-1 with TREK-1 variants alters TREK-1 expression and suppresses channel function. Each variant affected TREK-1 in a disparate manner. In HEK293T cells coexpressing TREK-1 and each variant, TREK-1 membrane expression was diminished with compartmentalization inside the cell. When expressed alone, individual variants displayed channel properties that were significantly decreased compared to full-length TREK-1. In coexpression studies using patch clamp, basal TREK-1 currents were reduced by ∼64% (4.3 vs. 12.0 pA/pF) on average at 0 mV when coexpressed with each variant. TREK-1 currents that were activated by intracellular acidosis were reduced an average of ∼77% (21.4 vs. 94.5 pA/pF) at 0 mV when cells were transfected with TREK-1 and any one of the splice variants. These data correlate the presence of TREK-1 variants to reduced TREK-1 activity, suggesting a pathological role for TREK-1 variants in preterm labor.
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Affiliation(s)
- Chad L Cowles
- Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada
| | - Yi-Ying Wu
- Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada
| | - Scott D Barnett
- Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada
| | - Michael T Lee
- Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada
| | - Heather R Burkin
- Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada
| | - Iain L O Buxton
- Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada
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Dick IE, Limpitikul WB, Niu J, Banerjee R, Issa JB, Ben-Johny M, Adams PJ, Kang PW, Lee SR, Sang L, Yang W, Babich J, Zhang M, Bazazzi H, Yue NC, Tomaselli GF. A rendezvous with the queen of ion channels: Three decades of ion channel research by David T Yue and his Calcium Signals Laboratory. Channels (Austin) 2015; 10:20-32. [PMID: 26176690 DOI: 10.1080/19336950.2015.1051272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
David T. Yue was a renowned biophysicist who dedicated his life to the study of Ca(2+) signaling in cells. In the wake of his passing, we are left not only with a feeling of great loss, but with a tremendous and impactful body of work contributed by a remarkable man. David's research spanned the spectrum from atomic structure to organ systems, with a quantitative rigor aimed at understanding the fundamental mechanisms underlying biological function. Along the way he developed new tools and approaches, enabling not only his own research but that of his contemporaries and those who will come after him. While we cannot hope to replicate the eloquence and style we are accustomed to in David's writing, we nonetheless undertake a review of David's chosen field of study with a focus on many of his contributions to the calcium channel field.
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Affiliation(s)
- Ivy E Dick
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Worawan B Limpitikul
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jacqueline Niu
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Rahul Banerjee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - John B Issa
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manu Ben-Johny
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Paul J Adams
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,b Kwantlen Polytechnic University ; Surrey , BC Canada
| | - Po Wei Kang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Shin Rong Lee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Lingjie Sang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Wanjun Yang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jennifer Babich
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manning Zhang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Hojjat Bazazzi
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Nancy C Yue
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Gordon F Tomaselli
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,c Division of Cardiology; Department of Medicine ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
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Meta-Analysis of Public Microarray Datasets Reveals Voltage-Gated Calcium Gene Signatures in Clinical Cancer Patients. PLoS One 2015; 10:e0125766. [PMID: 26147197 PMCID: PMC4493072 DOI: 10.1371/journal.pone.0125766] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 03/26/2015] [Indexed: 12/25/2022] Open
Abstract
Voltage-gated calcium channels (VGCCs) are well documented to play roles in cell proliferation, migration, and apoptosis; however, whether VGCCs regulate the onset and progression of cancer is still under investigation. The VGCC family consists of five members, which are L-type, N-type, T-type, R-type and P/Q type. To date, no holistic approach has been used to screen VGCC family genes in different types of cancer. We analyzed the transcript expression of VGCCs in clinical cancer tissue samples by accessing ONCOMINE (www.oncomine.org), a web-based microarray database, to perform a systematic analysis. Every member of the VGCCs was examined across 21 different types of cancer by comparing mRNA expression in cancer to that in normal tissue. A previous study showed that altered expression of mRNA in cancer tissue may play an oncogenic role and promote tumor development; therefore, in the present findings, we focus only on the overexpression of VGCCs in different types of cancer. This bioinformatics analysis revealed that different subtypes of VGCCs (CACNA1C, CACNA1D, CACNA1B, CACNA1G, and CACNA1I) are implicated in the development and progression of diverse types of cancer and show dramatic up-regulation in breast cancer. CACNA1F only showed high expression in testis cancer, whereas CACNA1A, CACNA1C, and CACNA1D were highly expressed in most types of cancer. The current analysis revealed that specific VGCCs likely play essential roles in specific types of cancer. Collectively, we identified several VGCC targets and classified them according to different cancer subtypes for prospective studies on the underlying carcinogenic mechanisms. The present findings suggest that VGCCs are possible targets for prospective investigation in cancer treatment.
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Soong TW, Mori MX. Post-transcriptional modifications and "Calmodulation" of voltage-gated calcium channel function: Reflections by two collaborators of David T Yue. Channels (Austin) 2015; 10:14-9. [PMID: 26054929 DOI: 10.1080/19336950.2015.1051271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
This review article is written to specially pay tribute to David T. Yue who was an outstanding human being and an excellent scientist who exuded passion and creativity. He exemplified an inter-disciplinary scientist who was able to cross scientific boundaries effortlessly in order to provide amazing understanding on how calcium channels work. This article provides a glimpse of some of the research the authors have the privilege to collaborate with David and it attempts to provide the thinking behind some of the research done. In a wider context, we highlight that calcium channel function could be exquisitely modulated by interaction with a tethered calmodulin. Post-transcriptional modifications such as alternative splicing and RNA editing further influence the Ca(2+)-CaM mediated processes such as calcium dependent inhibition and/or facilitation. Besides modifications of electrophysiological and pharmacological properties, protein interactions with the channels could also be influenced in a splice-variant dependent manner.
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Affiliation(s)
- Tuck Wah Soong
- a Department of Physiology ; Yong Loo Lin School of Medicine; National University of Singapore ; Singapore.,b NUS Graduate School for Integrative Science and Engineering, and Neurobiology/Aging Program ; Singapore.,c National Neuroscience Institute ; Singapore
| | - Masayuki X Mori
- d Kyoto University Department of Synthetic Chemistry and Biological Chemistry ; Graduate School of Engineering, Kyoto University ; Kyoto , Japan
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Schneider R, Hosy E, Kohl J, Klueva J, Choquet D, Thomas U, Voigt A, Heine M. Mobility of calcium channels in the presynaptic membrane. Neuron 2015; 86:672-9. [PMID: 25892305 DOI: 10.1016/j.neuron.2015.03.050] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 02/03/2015] [Accepted: 03/09/2015] [Indexed: 12/20/2022]
Abstract
Unravelling principles underlying neurotransmitter release are key to understand neural signaling. Here, we describe how surface mobility of voltage-dependent calcium channels (VDCCs) modulates release probabilities (P(r)) of synaptic vesicles (SVs). Coupling distances of <10 to >100 nm have been reported for SVs and VDCCs in different synapses. Tracking individual VDCCs revealed that within hippocampal synapses, ∼60% of VDCCs are mobile while confined to presynaptic membrane compartments. Intracellular Ca(2+) chelation decreased VDCC mobility. Increasing VDCC surface populations by co-expression of the α2δ1 subunit did not alter channel mobility but led to enlarged active zones (AZs) rather than higher channel densities. VDCCs thus scale presynaptic scaffolds to maintain local mobility. We propose that dynamic coupling based on mobile VDCCs supports calcium domain cooperativity and tunes neurotransmitter release by equalizing Pr for docked SVs within AZs.
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Affiliation(s)
- Romy Schneider
- Molecular Physiology Group, Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany
| | - Eric Hosy
- University of Bordeaux, F-33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France
| | - Johannes Kohl
- Harvard University, Department Molecular and Cellular Biology, Cambridge, MA 02138, USA
| | - Julia Klueva
- Molecular Physiology Group, Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany; Presynaptic Plasticity Group, Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany
| | - Daniel Choquet
- University of Bordeaux, F-33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France; Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, University of Bordeaux, F-33000 Bordeaux, France
| | - Ulrich Thomas
- Department Neurochemistry, Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany
| | - Andreas Voigt
- Otto-von-Guericke-University Magdeburg, Systemverfahrenstechnik, Universitätsplatz 2, D-39106 Magdeburg, Germany
| | - Martin Heine
- Molecular Physiology Group, Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany.
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Conservation of Ca2+/calmodulin regulation across Na and Ca2+ channels. Cell 2014; 157:1657-70. [PMID: 24949975 DOI: 10.1016/j.cell.2014.04.035] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 03/25/2014] [Accepted: 04/15/2014] [Indexed: 11/20/2022]
Abstract
Voltage-gated Na and Ca2+ channels comprise distinct ion channel superfamilies, yet the carboxy tails of these channels exhibit high homology, hinting at a long-shared and purposeful module. For different Ca2+ channels, carboxyl-tail interactions with calmodulin do elaborate robust and similar forms of Ca2+ regulation. However, Na channels have only shown subtler Ca2+ modulation that differs among reports, challenging attempts at unified understanding. Here, by rapid Ca2+ photorelease onto Na channels, we reset this view of Na channel regulation. For cardiac-muscle channels (NaV1.5), reported effects from which most mechanistic proposals derive, we observe no Ca2+ modulation. Conversely, for skeletal-muscle channels (NaV1.4), we uncover fast Ca2+ regulation eerily similar to that of Ca2+ channels. Channelopathic myotonia mutations halve NaV1.4 Ca2+ regulation, and transplanting the NaV1.4 carboxy tail onto Ca2+ channels recapitulates Ca2+ regulation. Thus, we argue for the persistence and physiological relevance of an ancient Ca2+ regulatory module across Na and Ca2+ channels.
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Simms BA, Zamponi GW. Neuronal voltage-gated calcium channels: structure, function, and dysfunction. Neuron 2014; 82:24-45. [PMID: 24698266 DOI: 10.1016/j.neuron.2014.03.016] [Citation(s) in RCA: 420] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Voltage-gated calcium channels are the primary mediators of depolarization-induced calcium entry into neurons. There is great diversity of calcium channel subtypes due to multiple genes that encode calcium channel α1 subunits, coassembly with a variety of ancillary calcium channel subunits, and alternative splicing. This allows these channels to fulfill highly specialized roles in specific neuronal subtypes and at particular subcellular loci. While calcium channels are of critical importance to brain function, their inappropriate expression or dysfunction gives rise to a variety of neurological disorders, including, pain, epilepsy, migraine, and ataxia. This Review discusses salient aspects of voltage-gated calcium channel function, physiology, and pathophysiology.
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Affiliation(s)
- Brett A Simms
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
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34
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Tyson JR, Snutch TP. Molecular nature of voltage‐gated calcium channels: structure and species comparison. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/wmts.91] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- John R. Tyson
- Michael Smith Laboratories University of British Columbia Vancouver BC Canada
| | - Terrance P. Snutch
- Michael Smith Laboratories University of British Columbia Vancouver BC Canada
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35
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Christel CJ, Schaer R, Wang S, Henzi T, Kreiner L, Grabs D, Schwaller B, Lee A. Calretinin regulates Ca2+-dependent inactivation and facilitation of Ca(v)2.1 Ca2+ channels through a direct interaction with the α12.1 subunit. J Biol Chem 2012; 287:39766-75. [PMID: 23033479 DOI: 10.1074/jbc.m112.406363] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Voltage-gated Ca(v)2.1 Ca(2+) channels undergo dual modulation by Ca(2+), Ca(2+)-dependent inactivation (CDI), and Ca(2+)-dependent facilitation (CDF), which can influence synaptic plasticity in the nervous system. Although the molecular determinants controlling CDI and CDF have been the focus of intense research, little is known about the factors regulating these processes in neurons. Here, we show that calretinin (CR), a Ca(2+)-binding protein highly expressed in subpopulations of neurons in the brain, inhibits CDI and enhances CDF by binding directly to α(1)2.1. Screening of a phage display library with CR as bait revealed a highly basic CR-binding domain (CRB) present in multiple copies in the cytoplasmic linker between domains II and III of α(1)2.1. In pulldown assays, CR binding to fusion proteins containing these CRBs was largely Ca(2+)-dependent. α(1)2.1 coimmunoprecipitated with CR antibodies from transfected cells and mouse cerebellum, which confirmed the existence of CR-Ca(v)2.1 complexes in vitro and in vivo. In HEK293T cells, CR significantly decreased Ca(v)2.1 CDI and increased CDF. CR binding to α(1)2.1 was required for these effects, because they were not observed upon substitution of the II-III linker of α(1)2.1 with that from the Ca(v)1.2 α(1) subunit (α(1)1.2), which lacks the CRBs. In addition, coexpression of a protein containing the CRBs blocked the modulatory action of CR, most likely by competing with CR for interactions with α(1)2.1. Our findings highlight an unexpected role for CR in directly modulating effectors such as Ca(v)2.1, which may have major consequences for Ca(2+) signaling and neuronal excitability.
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Affiliation(s)
- Carl J Christel
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, USA
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Abstract
Due to its high external and low internal concentration the Ca(2+) ion is used ubiquitously as an intracellular signaling molecule, and a great many Ca(2+)-sensing proteins have evolved to receive and propagate Ca(2+) signals. Among them are ion channel proteins, whose Ca(2+) sensitivity allows internal Ca(2+) to influence the electrical activity of cell membranes and to feedback-inhibit further Ca(2+) entry into the cytoplasm. In this review I will describe what is understood about the Ca(2+) sensing mechanisms of the three best studied classes of Ca(2+)-sensitive ion channels: Large-conductance Ca(2+)-activated K(+) channels, small-conductance Ca(2+)-activated K(+) channels, and voltage- gated Ca(2+) channels. Great strides in mechanistic understanding have be made for each of these channel types in just the past few years.
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Affiliation(s)
- Daniel H Cox
- Department of Neuroscience, Tufts University School of Medicine, Boston MA, 02420, USA.
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Christel C, Lee A. Ca2+-dependent modulation of voltage-gated Ca2+ channels. Biochim Biophys Acta Gen Subj 2011; 1820:1243-52. [PMID: 22223119 DOI: 10.1016/j.bbagen.2011.12.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Revised: 12/15/2011] [Accepted: 12/16/2011] [Indexed: 01/06/2023]
Abstract
BACKGROUND Voltage-gated (Cav) Ca2+ channels are multi-subunit complexes that play diverse roles in a wide variety of tissues. A fundamental mechanism controlling Cav channel function involves the Ca2+ ions that permeate the channel pore. Ca2+ influx through Cav channels mediates feedback regulation to the channel that is both negative (Ca2+-dependent inactivation, CDI) and positive (Ca2+-dependent facilitation, CDF). SCOPE OF REVIEW This review highlights general mechanisms of CDI and CDF with an emphasis on how these processes have been studied electrophysiologically in native and heterologous expression systems. MAJOR CONCLUSIONS Electrophysiological analyses have led to detailed insights into the mechanisms and prevalence of CDI and CDF as Cav channel regulatory mechanisms. All Cav channel family members undergo some form of Ca2+-dependent feedback that relies on CaM or a related Ca2+ binding protein. Tremendous progress has been made in characterizing the role of CaM in CDI and CDF. Yet, what contributes to the heterogeneity of CDI/CDF in various cell-types and how Ca2+-dependent regulation of Cav channels controls Ca2+ signaling remain largely unexplored. GENERAL SIGNIFICANCE Ca2+ influx through Cav channels regulates diverse physiological events including excitation-contraction coupling in muscle, neurotransmitter and hormone release, and Ca2+-dependent gene transcription. Therefore, the mechanisms that regulate channels, such as CDI and CDF, can have a large impact on the signaling potential of excitable cells in various physiological contexts. This article is part of a Special Issue entitled Biochemical, biophysical and genetic approaches to intracellular calcium signaling.
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Affiliation(s)
- Carl Christel
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
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Tsou WL, Soong BW, Paulson HL, Rodríguez-Lebrón E. Splice isoform-specific suppression of the Cav2.1 variant underlying spinocerebellar ataxia type 6. Neurobiol Dis 2011; 43:533-42. [PMID: 21550405 DOI: 10.1016/j.nbd.2011.04.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 04/08/2011] [Accepted: 04/21/2011] [Indexed: 01/23/2023] Open
Abstract
Spinocerebellar ataxia type 6 (SCA6) is an inherited neurodegenerative disease caused by a polyglutamine (polyQ) expansion in the Ca(V)2.1 voltage-gated calcium channel subunit (CACNA1A). There is currently no treatment for this debilitating disorder and thus a pressing need to develop preventative therapies. RNA interference (RNAi) has proven effective at halting disease progression in several models of spinocerebellar ataxia (SCA), including SCA types 1 and 3. However, in SCA6 and other dominantly inherited neurodegenerative disorders, RNAi-based strategies that selectively suppress expression of mutant alleles may be required. Using a Ca(V)2.1 mini-gene reporter system, we found that pathogenic CAG expansions in Ca(V)2.1 enhance splicing activity at the 3'end of the transcript, leading to a CAG repeat length-dependent increase in the levels of a polyQ-encoding Ca(V)2.1 mRNA splice isoform and the resultant disease protein. Taking advantage of this molecular phenomenon, we developed a novel splice isoform-specific (SIS)-RNAi strategy that selectively targets the polyQ-encoding Ca(V)2.1 splice variant. Selective suppression of transiently expressed and endogenous polyQ-encoding Ca(V)2.1 splice variants was achieved in a variety of cell-based models including a human neuronal cell line, using a new artificial miRNA-like delivery system. Moreover, the efficacy of gene silencing correlated with effective intracellular recognition and processing of SIS-RNAi miRNA mimics. These results lend support to the preclinical development of SIS-RNAi as a potential therapy for SCA6 and other dominantly inherited diseases.
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Affiliation(s)
- Wei-Ling Tsou
- Institute of Neuroscience, School of Life Sciences, National Yang-Ming University, Taipei, Taiwan
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Contribution of calcium-dependent facilitation to synaptic plasticity revealed by migraine mutations in the P/Q-type calcium channel. Proc Natl Acad Sci U S A 2010; 107:18694-9. [PMID: 20937883 DOI: 10.1073/pnas.1009500107] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The dynamics, computational power, and strength of neural circuits are essential for encoding and processing information in the CNS and rely on short and long forms of synaptic plasticity. In a model system, residual calcium (Ca(2+)) in presynaptic terminals can act through neuronal Ca(2+) sensor proteins to cause Ca(2+)-dependent facilitation (CDF) of P/Q-type channels and induce short-term synaptic facilitation. However, whether this is a general mechanism of plasticity at intact central synapses and whether mutations associated with human disease affect this process have not been described to our knowledge. In this report, we find that, in both exogenous and native preparations, gain-of-function missense mutations underlying Familial Hemiplegic Migraine type 1 (FHM-1) occlude CDF of P/Q-type Ca(2+) channels. In FHM-1 mutant mice, the alteration of P/Q-type channel CDF correlates with reduced short-term synaptic facilitation at cerebellar parallel fiber-to-Purkinje cell synapses. Two-photon imaging suggests that P/Q-type channels at parallel fiber terminals in FHM-1 mice are in a basally facilitated state. Overall, the results provide evidence that FHM-1 mutations directly affect both P/Q-type channel CDF and synaptic plasticity and that together likely contribute toward the pathophysiology underlying FHM-1. The findings also suggest that P/Q-type channel CDF is an important mechanism required for normal synaptic plasticity at a fast synapse in the mammalian CNS.
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Mantuano E, Romano S, Veneziano L, Gellera C, Castellotti B, Caimi S, Testa D, Estienne M, Zorzi G, Bugiani M, Rajabally YA, Barcina MJG, Servidei S, Panico A, Frontali M, Mariotti C. Identification of novel and recurrent CACNA1A gene mutations in fifteen patients with episodic ataxia type 2. J Neurol Sci 2010; 291:30-6. [PMID: 20129625 DOI: 10.1016/j.jns.2010.01.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 12/02/2009] [Accepted: 01/12/2010] [Indexed: 10/19/2022]
Abstract
Episodic ataxia type 2 is a rare autosomal dominant disease characterized by recurrent attacks of vertigo and cerebellar ataxia. The disease was caused by mutations in the CACNA1A gene, on chromosome 19p. We perform a mutational screening in a group of 43 unrelated patients. Forty-two patients presented episodes of disequilibrium and ataxia, and one child was studied because of the occurrence of episodic torticollis. The genetic analysis showed 15 mutated patients (35%). In 13 cases we found novel CACNA1A gene mutations, including missense, protein truncating, and aberrant splicing mutations. Two truncating mutations lead to the uppermost premature stop so far reported, challenging recent hypotheses on dominant negative effect. In patients without CACNA1A mutations, molecular testing for CACNB4 gene mutations excluded this genetic subtype. Clinical features of mutated subjects mostly confirmed previous sign and symptoms associated with EA2, including paroxysmal torticollis and mental retardation. CACNA1A mutated patients have an earlier age at onset, interictal nystagmus, and abnormalities of ocular movements. A review of all CACNA1A mutations so far reported showed that they are mainly located downstream exon 18. Our data substantially increase the number of the described CACNA1A mutations, and propose clinical and molecular criteria for a more focused genetic screening.
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Affiliation(s)
- Elide Mantuano
- Institute of Neurobiology and Molecular Medicine, CNR, Rome, Italy
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Pulver SR, Griffith LC. Spike integration and cellular memory in a rhythmic network from Na+/K+ pump current dynamics. Nat Neurosci 2009; 13:53-9. [PMID: 19966842 PMCID: PMC2839136 DOI: 10.1038/nn.2444] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Accepted: 10/14/2009] [Indexed: 11/18/2022]
Abstract
The output of a neural circuit results from an interaction between the intrinsic properties of neurons within the circuit and the features of the synaptic connections between them. The plasticity of intrinsic properties has been primarily attributed to modification of ion channel function and/or number. In this study, we demonstrate a mechanism for intrinsic plasticity in rhythmically active Drosophila neurons that is not conductance-based. Larval motor neurons show a long lasting sodium-dependent afterhyperpolarization (AHP) following bursts of action potentials that is mediated by the electrogenic activity of Na+/K+ ATPase. This AHP persists for multiple seconds following volleys of action potentials and is able to function as a pattern-insensitive integrator of spike number that is independent of external calcium. This current also interacts with endogenous Shal K+ conductances to modulate spike timing for multiple seconds following rhythmic activity, providing a cellular memory of network activity on a behaviorally relevant time scale.
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Affiliation(s)
- Stefan R Pulver
- Brandeis University, Department of Biology, National Center of Behavioral Genomics and Volen Center for Complex Systems, Waltham, Massachusetts, USA
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42
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Benton MD, Raman IM. Stabilization of Ca current in Purkinje neurons during high-frequency firing by a balance of Ca-dependent facilitation and inactivation. Channels (Austin) 2009; 3:393-401. [PMID: 19806011 PMCID: PMC2897944 DOI: 10.4161/chan.3.6.9838] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Purkinje neurons fire spontaneous action potentials at ∼50 spikes/sec and generate more than 100 spikes/sec during cerebellum-mediated behaviors. Many voltage-gated channels, including Ca channels, can inactivate and/or facilitate with repeated stimulation, raising the question of how these channels respond to regular, rapid trains of depolarizations. To test whether Ca currents are modulated during firing, we recorded voltage-clamped Ca currents, predominantly carried by P-type Ca channels, from acutely dissociated mouse Purkinje neurons at 30-33°C (1 mM Ca). With 0.5 mM intracellular EGTA, 1-second trains of either spontaneous action potential waveforms or brief depolarizing steps at 50 Hz evoked Ca tail currents that were stable, remaining within 5% of the first tail current throughout the train. Higher frequency trains (100 and 200 Hz) elicited a maximal inactivation of <10%. To test whether this stability of Ca currents resulted from a lack of modulation or from an equilibrium between facilitation and inactivation, we manipulated the permeant ion (Ca vs. Ba) and Ca buffering (0.5 vs. 10 mM EGTA). With low buffering, Ba accelerated the initial inactivation evoked by 1-second trains, but reduced its extent at 200 Hz, consistent with an early calcium-dependent facilitation (CDF) and late calcium-dependent inactivation (CDI) at high frequencies. Increasing the Ca buffer favored CDF. These data suggest that stable Ca current amplitudes result from a balance of CDF, CDI, and voltage-dependent inactivation. This modest net Ca-dependent modulation may contribute to the ability of Purkinje neurons to sustain long periods of regular firing and synaptic transmission.
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Affiliation(s)
- Mark D. Benton
- Interdepartmental Neuroscience Program; Northwestern University; Evanston, IL USA
| | - Indira M. Raman
- Interdepartmental Neuroscience Program; Northwestern University; Evanston, IL USA,Department of Neurobiology and Physiology; Northwestern University; Evanston, IL USA,Correspondence to: Indira M. Raman;
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43
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Fricker D, Dinocourt C, Eugène E, Wood JN, Wood J, Miles R. Pyramidal cells of rodent presubiculum express a tetrodotoxin-insensitive Na+ current. J Physiol 2009; 587:4249-64. [PMID: 19596892 DOI: 10.1113/jphysiol.2009.175349] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Presubicular neurons are activated physiologically by a specific preferred head direction. Here we show that firing in these neurones is characterized by action potentials with a large overshoot and a reduced firing frequency adaptation during repetitive firing. We found that a component of the sodium current of presubicular cells was not abolished by tetrodotoxin (TTX, 10 mum) and was activated at more depolarized voltages than TTX-sensitive currents. This inward current was completely abolished by the removal of external sodium, suggesting that sodium is the charge carrier of this TTX-insensitive (TTX-I) current. The channels responsible for the TTX-I sodium current seemed to be expressed at sites distant from the soma, giving rise to a voltage-dependent delay in current activation. The voltage required for half-maximal activation was 21 mV, and 36 mV for inactivation, which is similar to that reported for Na(V)1.8 sodium channels. However, the kinetics were considerably slower, with a time constant of current decay of 1.4 s. The current was not abolished in pyramidal cells from animals lacking either the Na(V)1.8 or the Na(V)1.9 subunit. This, possibly novel, TTX-I sodium current could contribute to the coding functions of presubicular neurons, specifically the maintained firing associated with signalling of a stable head position.
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Affiliation(s)
- Desdemona Fricker
- CRICM - CNRS UMR7225, CHU Pitié-Salpêtrière, 105 Bd de l'Hôpital, 75013 Paris, France.
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44
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Liao P, Zhang HY, Soong TW. Alternative splicing of voltage-gated calcium channels: from molecular biology to disease. Pflugers Arch 2009; 458:481-7. [PMID: 19151996 DOI: 10.1007/s00424-009-0635-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 01/07/2009] [Indexed: 12/01/2022]
Abstract
Recent developments in the diversification of voltage-gated calcium channel function center on the rapidly emerging role of the posttranscriptional mechanism of alternative splicing. A number of diseases have been found to relate to the dysfunction of alternatively spliced exons arising from either genetic mutations or alterations in the splicing machinery. Mutations in some genes associated with congenital diseases have been detected to reside in alternatively spliced exons. As such, the severity of tissue-selective pathology of the disease will depend on the level of expression of the alternatively spliced exons in that tissue, as well as the extent in the change in channel properties. Importantly, alteration in channel properties is affected by the backbone array of the combinatorial alternatively spliced exons within the channel. In other words, the context by which mutations or alternatively spliced exons are expressed is a great influence on the alteration of channel properties and as such physiology and disease. We reviewed here recent comprehension of alternative splicing of voltage-gated calcium channels and how such structural and functional diversity of voltage-gated calcium channels will aid to clarify the pathophysiology of relevant diseases. Such understandings will further provide guidance for novel treatment.
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Affiliation(s)
- Ping Liao
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Kent Ridge, Singapore
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45
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Sun XX, Bostrom SL, Griffith LC. Alternative splicing of the eag potassium channel gene in Drosophila generates a novel signal transduction scaffolding protein. Mol Cell Neurosci 2008; 40:338-43. [PMID: 19130887 DOI: 10.1016/j.mcn.2008.11.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2008] [Revised: 11/08/2008] [Accepted: 11/21/2008] [Indexed: 01/24/2023] Open
Abstract
The Drosophila eag gene has been shown to regulate neuronal excitability, olfaction, associative learning and larval locomotion. Not all of the roles of this gene in these processes can be explained by its function as a voltage-gated potassium channel. In this study, we show that the eag gene is spliced in a PKA- and PKC-regulated manner to produce a protein lacking channel domains. This protein, in the context of activated PKA, can engage cellular signaling pathways that alter cell structure. Nuclear localization is necessary for C-terminal-mediated effects, which also require MAPK. The requirement for PKA/PKC activation in the synthesis and function of this novel protein suggests that it may couple membrane events to nuclear signaling to regulate neuronal function on long time scales.
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Affiliation(s)
- Xiu Xia Sun
- Department of Biology, National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454-9110, USA
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46
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Calcium Channel Regulation and Presynaptic Plasticity. Neuron 2008; 59:882-901. [PMID: 18817729 DOI: 10.1016/j.neuron.2008.09.005] [Citation(s) in RCA: 463] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 09/05/2008] [Accepted: 09/05/2008] [Indexed: 01/15/2023]
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47
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Xie J. Control of alternative pre-mRNA splicing by Ca(++) signals. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1779:438-52. [PMID: 18258215 PMCID: PMC3500379 DOI: 10.1016/j.bbagrm.2008.01.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 12/18/2007] [Accepted: 01/08/2008] [Indexed: 02/06/2023]
Abstract
Alternative pre-mRNA splicing is a common way of gene expression regulation in metazoans. The selective use of specific exons can be modulated in response to various manipulations that alter Ca(++) signals, particularly in neurons. A number of splicing factors have also been found to be controlled by Ca(++) signals. Moreover, pre-mRNA elements have been identified that are essential and sufficient to mediate Ca(++)-regulated splicing, providing model systems for dissecting the involved molecular components. In neurons, this regulation likely contributes to the fine-tuning of neuronal properties.
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Affiliation(s)
- Jiuyong Xie
- Department of Physiology, Faculty of Medicine, University of Manitoba, 730 William Avenue, Winnipeg, Canada MB R3E 3J7.
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Graves TD, Imbrici P, Kors EE, Terwindt GM, Eunson LH, Frants RR, Haan J, Ferrari MD, Goadsby PJ, Hanna MG, van den Maagdenberg AMJM, Kullmann DM. Premature stop codons in a facilitating EF-hand splice variant of CaV2.1 cause episodic ataxia type 2. Neurobiol Dis 2008; 32:10-5. [PMID: 18606230 DOI: 10.1016/j.nbd.2008.06.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Accepted: 06/05/2008] [Indexed: 10/22/2022] Open
Abstract
Premature stop codons in CACNA1A, which encodes the alpha(1A) subunit of neuronal P/Q-type (Ca(V)2.1) Ca(2+) channels, cause episodic ataxia type 2 (EA2). CACNA1A undergoes extensive alternative splicing, which contributes to the pharmacological and kinetic heterogeneity of Ca(V)2.1-mediated Ca(2+) currents. We identified three novel heterozygous stop codon mutations associated with EA2 in an alternately spliced exon (37A), which encodes part of an EF-hand motif required for Ca(2+)-dependent facilitation. One family had a C to G transversion (Y1854X). A dinucleotide deletion results in the same premature stop codon in a second family, and a further single nucleotide change leads to a different truncation (R1858X) in a de novo case of EA2. Expression studies of the Y1854X mutation revealed loss of Ca(V)2.1-mediated current. Because these mutations do not affect the alternate exon 37B, these findings reveal unexpected dependence of cerebellar function on intact exon 37A-containing Ca(V)2.1 channels.
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Affiliation(s)
- Tracey D Graves
- Institute of Neurology, University College London, Queen Square, London, United Kingdom
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Crystal structure of the CaV2 IQ domain in complex with Ca2+/calmodulin: high-resolution mechanistic implications for channel regulation by Ca2+. Structure 2008; 16:607-20. [PMID: 18400181 DOI: 10.1016/j.str.2008.01.011] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 01/12/2008] [Accepted: 01/22/2008] [Indexed: 11/21/2022]
Abstract
Calmodulin (CaM) regulation of Ca(2+) channels is central to Ca(2+) signaling. Ca(V)1 versus Ca(V)2 classes of these channels exhibit divergent forms of regulation, potentially relating to customized CaM/IQ interactions among different channels. Here we report the crystal structures for the Ca(2+)/CaM IQ domains of both Ca(V)2.1 and Ca(V)2.3 channels. These highly similar structures emphasize that major CaM contacts with the IQ domain extend well upstream of traditional consensus residues. Surprisingly, upstream mutations strongly diminished Ca(V)2.1 regulation, whereas downstream perturbations had limited effects. Furthermore, our Ca(V)2 structures closely resemble published Ca(2+)/CaM-Ca(V)1.2 IQ structures, arguing against Ca(V)1/2 regulatory differences based solely on contrasting CaM/IQ conformations. Instead, alanine scanning of the Ca(V)2.1 IQ domain, combined with structure-based molecular simulation of corresponding CaM/IQ binding energy perturbations, suggests that the C lobe of CaM partially dislodges from the IQ element during channel regulation, allowing exposed IQ residues to trigger regulation via isoform-specific interactions with alternative channel regions.
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50
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Nakamura T, Yamashita T, Saitoh N, Takahashi T. Developmental changes in calcium/calmodulin-dependent inactivation of calcium currents at the rat calyx of Held. J Physiol 2008; 586:2253-61. [PMID: 18238813 DOI: 10.1113/jphysiol.2007.142521] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Ca2+-binding to calmodulin (CaM) causes facilitation and/or inactivation of recombinant Ca2+ channels. At the rat calyx of Held, before hearing onset, presynaptic Ca2+ currents (IpCa) undergo Ca2+/CaM-dependent inactivation during repetitive activation at around 1 Hz, implying that this may be a major cause of short-term synaptic depression. However, it remains open whether the Ca2+/CaM-dependent inactivation of IpCa persists in more mature animals. To address this question, we tested the effect of CaM inhibitors on the activity-dependent modulation of IpCa in calyces, before (postnatal day (P) 7-9) and after (P13-15) hearing onset. Our results indicate that the CaM-dependent IpCa inactivation during low-frequency stimulation, and the ensuing synaptic depression, occur only at calyces in the prehearing period. However, CaM immunoreactivity in P8 and P14 calyces was equally strong. Even at P13-15, high frequency stimulation (200-500 Hz) could induce IpCa inactivation, which was attenuated by EGTA (10 mM) or a CaM inhibitor peptide loaded into the terminal. Furthermore, the CaM inhibitor peptide attenuated a transient facilitation of IpCa preceding inactivation observed at 500 Hz stimulation, whereas it had no effect on sustained IpCa facilitations during trains of 50-200 Hz stimulation. These results suggest that the Ca2+/CaM-dependent IpCa modulation requires a high intraterminal Ca2+ concentration, which can be attained at immature calyces during low frequency stimulation, but only during unusually high frequency stimulation at calyceal terminals in the posthearing period.
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Affiliation(s)
- Takeshi Nakamura
- Doshisha University, Faculty of Life and Medical Sciences, Kyoto 619-0225, Japan
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