1
|
Dong Y, Gao Y, Xu S, Wang Y, Yu Z, Li Y, Li B, Yuan T, Yang B, Zhang XC, Jiang D, Huang Z, Zhao Y. Closed-state inactivation and pore-blocker modulation mechanisms of human Ca V2.2. Cell Rep 2021; 37:109931. [PMID: 34731621 DOI: 10.1016/j.celrep.2021.109931] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/13/2021] [Accepted: 10/11/2021] [Indexed: 11/19/2022] Open
Abstract
N-type voltage-gated calcium (CaV) channels mediate Ca2+ influx at presynaptic terminals in response to action potentials and play vital roles in synaptogenesis, release of neurotransmitters, and nociceptive transmission. Here, we elucidate a cryo-electron microscopy (cryo-EM) structure of the human CaV2.2 complex in apo, ziconotide-bound, and two CaV2.2-specific pore blockers-bound states. The second voltage-sensing domain (VSD) is captured in a resting-state conformation, trapped by a phosphatidylinositol 4,5-bisphosphate (PIP2) molecule, which is distinct from the other three VSDs of CaV2.2, as well as activated VSDs observed in previous structures of CaV channels. This structure reveals the molecular basis for the unique inactivation process of CaV2.2 channels, in which the intracellular gate formed by S6 helices is closed and a W-helix from the domain II-III linker stabilizes closed-state inactivation. The structures of this inactivated, drug-bound complex lay a solid foundation for developing new state-dependent blockers for treatment of chronic pain.
Collapse
Affiliation(s)
- Yanli Dong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yiwei Gao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuai Xu
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Yuhang Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhuoya Yu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yue Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bin Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tian Yuan
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Bei Yang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xuejun Cai Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Daohua Jiang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China.
| | - Yan Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
| |
Collapse
|
2
|
Ottolini M, Sonkusare SK. The Calcium Signaling Mechanisms in Arterial Smooth Muscle and Endothelial Cells. Compr Physiol 2021; 11:1831-1869. [PMID: 33792900 PMCID: PMC10388069 DOI: 10.1002/cphy.c200030] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The contractile state of resistance arteries and arterioles is a crucial determinant of blood pressure and blood flow. Physiological regulation of arterial contractility requires constant communication between endothelial and smooth muscle cells. Various Ca2+ signals and Ca2+ -sensitive targets ensure dynamic control of intercellular communications in the vascular wall. The functional effect of a Ca2+ signal on arterial contractility depends on the type of Ca2+ -sensitive target engaged by that signal. Recent studies using advanced imaging methods have identified the spatiotemporal signatures of individual Ca2+ signals that control arterial and arteriolar contractility. Broadly speaking, intracellular Ca2+ is increased by ion channels and transporters on the plasma membrane and endoplasmic reticular membrane. Physiological roles for many vascular Ca2+ signals have already been confirmed, while further investigation is needed for other Ca2+ signals. This article focuses on endothelial and smooth muscle Ca2+ signaling mechanisms in resistance arteries and arterioles. We discuss the Ca2+ entry pathways at the plasma membrane, Ca2+ release signals from the intracellular stores, the functional and physiological relevance of Ca2+ signals, and their regulatory mechanisms. Finally, we describe the contribution of abnormal endothelial and smooth muscle Ca2+ signals to the pathogenesis of vascular disorders. © 2021 American Physiological Society. Compr Physiol 11:1831-1869, 2021.
Collapse
Affiliation(s)
- Matteo Ottolini
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | - Swapnil K Sonkusare
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA.,Department of Molecular Physiology & Biological Physics, University of Virginia, Charlottesville, Virginia, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
| |
Collapse
|
3
|
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]
|
4
|
Mochida S. Neurotransmitter Release Site Replenishment and Presynaptic Plasticity. Int J Mol Sci 2020; 22:ijms22010327. [PMID: 33396919 PMCID: PMC7794938 DOI: 10.3390/ijms22010327] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 12/23/2020] [Accepted: 12/27/2020] [Indexed: 12/19/2022] Open
Abstract
An action potential (AP) triggers neurotransmitter release from synaptic vesicles (SVs) docking to a specialized release site of presynaptic plasma membrane, the active zone (AZ). The AP simultaneously controls the release site replenishment with SV for sustainable synaptic transmission in response to incoming neuronal signals. Although many studies have suggested that the replenishment time is relatively slow, recent studies exploring high speed resolution have revealed SV dynamics with milliseconds timescale after an AP. Accurate regulation is conferred by proteins sensing Ca2+ entering through voltage-gated Ca2+ channels opened by an AP. This review summarizes how millisecond Ca2+ dynamics activate multiple protein cascades for control of the release site replenishment with release-ready SVs that underlie presynaptic short-term plasticity.
Collapse
Affiliation(s)
- Sumiko Mochida
- Department of Physiology, Tokyo Medical University, Tokyo 160-8402, Japan
| |
Collapse
|
5
|
Segura E, Mehta A, Marsolais M, Quan XR, Zhao J, Sauvé R, Spafford JD, Parent L. An ancestral MAGUK protein supports the modulation of mammalian voltage-gated Ca 2+ channels through a conserved Ca Vβ-like interface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183439. [PMID: 32814116 DOI: 10.1016/j.bbamem.2020.183439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/11/2020] [Accepted: 08/03/2020] [Indexed: 01/09/2023]
Abstract
Eukaryote voltage-gated Ca2+ channels of the CaV2 channel family are hetero-oligomers formed by the pore-forming CaVα1 protein assembled with auxiliary CaVα2δ and CaVβ subunits. CaVβ subunits are formed by a Src homology 3 (SH3) domain and a guanylate kinase (GK) domain connected through a HOOK domain. The GK domain binds a conserved cytoplasmic region of the pore-forming CaVα1 subunit referred as the "AID". Herein we explored the phylogenetic and functional relationship between CaV channel subunits in distant eukaryotic organisms by investigating the function of a MAGUK protein (XM_004990081) cloned from the choanoflagellate Salpingoeca rosetta (Sro). This MAGUK protein (Sroβ) features SH3 and GK structural domains with a 25% primary sequence identity to mammalian CaVβ. Recombinant expression of its cDNA with mammalian high-voltage activated Ca2+ channel CaV2.3 in mammalian HEK cells produced robust voltage-gated inward Ca2+ currents with typical activation and inactivation properties. Like CaVβ, Sroβ prevents fast degradation of total CaV2.3 proteins in cycloheximide assays. The three-dimensional homology model predicts an interaction between the GK domain of Sroβ and the AID motif of the pore-forming CaVα1 protein. Substitution of AID residues Trp (W386A) and Tyr (Y383A) significantly impaired co-immunoprecipitation of CaV2.3 with Sroβ and functional upregulation of CaV2.3 currents. Likewise, a 6-residue deletion within the GK domain of Sroβ, similar to the locus found in mammalian CaVβ, significantly reduced peak current density. Altogether our data demonstrate that an ancestor MAGUK protein reconstitutes the biophysical and molecular features responsible for channel upregulation by mammalian CaVβ through a minimally conserved molecular interface.
Collapse
Affiliation(s)
- Emilie Segura
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Canada; Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada
| | - Amrit Mehta
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Mireille Marsolais
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada
| | - Xin R Quan
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Juan Zhao
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada
| | - Rémy Sauvé
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Canada
| | - J David Spafford
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Lucie Parent
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Canada; Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada.
| |
Collapse
|
6
|
Li B, He X, Dong Z, Xuan K, Sun W, Gao L, Liu S, Liu W, Hu C, Zhao Y, Shi S, Jin Y. Ionomycin ameliorates hypophosphatasia via rescuing alkaline phosphatase deficiency-mediated L-type Ca 2+ channel internalization in mesenchymal stem cells. Bone Res 2020; 8:19. [PMID: 32351759 PMCID: PMC7183511 DOI: 10.1038/s41413-020-0090-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 10/02/2019] [Accepted: 01/05/2020] [Indexed: 12/26/2022] Open
Abstract
The loss-of-function mutations in the ALPL result in hypophosphatasia (HPP), an inborn metabolic disorder that causes skeletal mineralization defects. In adults, the main clinical features are early loss of primary or secondary teeth, osteoporosis, bone pain, chondrocalcinosis, and fractures. However, guidelines for the treatment of adults with HPP are not available. Here, we show that ALPL deficiency caused a reduction in intracellular Ca2+ influx, resulting in an osteoporotic phenotype due to downregulated osteogenic differentiation and upregulated adipogenic differentiation in both human and mouse bone marrow mesenchymal stem cells (BMSCs). Increasing the intracellular level of calcium in BMSCs by ionomycin treatment rescued the osteoporotic phenotype in alpl+/- mice and BMSC-specific (Prrx1-alpl-/-) conditional alpl knockout mice. Mechanistically, ALPL was found to be required for the maintenance of intracellular Ca2+ influx, which it achieves by regulating L-type Ca2+ channel trafficking via binding to the α2δ subunits to regulate the internalization of the L-type Ca2+ channel. Decreased Ca2+ flux inactivates the Akt/GSK3β/β-catenin signaling pathway, which regulates lineage differentiation of BMSCs. This study identifies a previously unknown role of the ectoenzyme ALPL in the maintenance of calcium channel trafficking to regulate stem cell lineage differentiation and bone homeostasis. Accelerating Ca2+ flux through L-type Ca2+ channels by ionomycin treatment may be a promising therapeutic approach for adult patients with HPP.
Collapse
Affiliation(s)
- Bei Li
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Center for Tissue Engineering, School of Stomatology, The Fourth Military Medical University, Xi’an, 710032 Shaanxi China
- Xi’an Institute of Tissue Engineering and Regenerative Medicine, Xi’an, China
| | - Xiaoning He
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Center for Tissue Engineering, School of Stomatology, The Fourth Military Medical University, Xi’an, 710032 Shaanxi China
- Xi’an Institute of Tissue Engineering and Regenerative Medicine, Xi’an, China
| | - Zhiwei Dong
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Center for Tissue Engineering, School of Stomatology, The Fourth Military Medical University, Xi’an, 710032 Shaanxi China
| | - Kun Xuan
- Department of Pediatric Dentistry, School of Stomatology, Fourth Military Medical University, Xi’an, China
| | - Wei Sun
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
| | - Li Gao
- Department of Pediatric Dentistry, School of Stomatology, Fourth Military Medical University, Xi’an, China
| | - Shiyu Liu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Center for Tissue Engineering, School of Stomatology, The Fourth Military Medical University, Xi’an, 710032 Shaanxi China
- Xi’an Institute of Tissue Engineering and Regenerative Medicine, Xi’an, China
| | - Wenjia Liu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Center for Tissue Engineering, School of Stomatology, The Fourth Military Medical University, Xi’an, 710032 Shaanxi China
- Xi’an Institute of Tissue Engineering and Regenerative Medicine, Xi’an, China
| | - Chenghu Hu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Center for Tissue Engineering, School of Stomatology, The Fourth Military Medical University, Xi’an, 710032 Shaanxi China
- Xi’an Institute of Tissue Engineering and Regenerative Medicine, Xi’an, China
| | - Yimin Zhao
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Center for Tissue Engineering, School of Stomatology, The Fourth Military Medical University, Xi’an, 710032 Shaanxi China
| | - Songtao Shi
- Department of Anatomy and Cell Biology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA USA
- South China Center of Craniofacial Stem Cell Research, Guanghua School of Stomatology, Sun Yat-sen University, 74 Zhongshan 2Rd, Guangzhou, Guangdong China
| | - Yan Jin
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Center for Tissue Engineering, School of Stomatology, The Fourth Military Medical University, Xi’an, 710032 Shaanxi China
- Xi’an Institute of Tissue Engineering and Regenerative Medicine, Xi’an, China
| |
Collapse
|
7
|
Presynaptic Calcium Channels. Int J Mol Sci 2019; 20:ijms20092217. [PMID: 31064106 PMCID: PMC6539076 DOI: 10.3390/ijms20092217] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/22/2019] [Accepted: 04/26/2019] [Indexed: 12/27/2022] Open
Abstract
Presynaptic Ca2+ entry occurs through voltage-gated Ca2+ (CaV) channels which are activated by membrane depolarization. Depolarization accompanies neuronal firing and elevation of Ca2+ triggers neurotransmitter release from synaptic vesicles. For synchronization of efficient neurotransmitter release, synaptic vesicles are targeted by presynaptic Ca2+ channels forming a large signaling complex in the active zone. The presynaptic CaV2 channel gene family (comprising CaV2.1, CaV2.2, and CaV2.3 isoforms) encode the pore-forming α1 subunit. The cytoplasmic regions are responsible for channel modulation by interacting with regulatory proteins. This article overviews modulation of the activity of CaV2.1 and CaV2.2 channels in the control of synaptic strength and presynaptic plasticity.
Collapse
|
8
|
Presynaptic calcium channels. Neurosci Res 2018; 127:33-44. [DOI: 10.1016/j.neures.2017.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 07/13/2017] [Accepted: 08/23/2017] [Indexed: 12/30/2022]
|
9
|
Du X, Gomez CM. Spinocerebellar [corrected] Ataxia Type 6: Molecular Mechanisms and Calcium Channel Genetics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1049:147-173. [PMID: 29427102 DOI: 10.1007/978-3-319-71779-1_7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Spinocerebellar ataxia (SCA) type 6 is an autosomal dominant disease affecting cerebellar degeneration. Clinically, it is characterized by pure cerebellar dysfunction, slowly progressive unsteadiness of gait and stance, slurred speech, and abnormal eye movements with late onset. Pathological findings of SCA6 include a diffuse loss of Purkinje cells, predominantly in the cerebellar vermis. Genetically, SCA6 is caused by expansion of a trinucleotide CAG repeat in the last exon of longest isoform CACNA1A gene on chromosome 19p13.1-p13.2. Normal alleles have 4-18 repeats, while alleles causing disease contain 19-33 repeats. Due to presence of a novel internal ribosomal entry site (IRES) with the mRNA, CACNA1A encodes two structurally unrelated proteins with distinct functions within an overlapping open reading frame (ORF) of the same mRNA: (1) α1A subunit of P/Q-type voltage gated calcium channel; (2) α1ACT, a newly recognized transcription factor, with polyglutamine repeat at C-terminal end. Understanding the function of α1ACT in physiological and pathological conditions may elucidate the pathogenesis of SCA6. More importantly, the IRES, as the translational control element of α1ACT, provides a potential therapeutic target for the treatment of SCA6.
Collapse
Affiliation(s)
- Xiaofei Du
- Department of Neurology, The University of Chicago, Chicago, 60637, IL, USA
| | | |
Collapse
|
10
|
Bilirubin augments Ca 2+ load of developing bushy neurons by targeting specific subtype of voltage-gated calcium channels. Sci Rep 2017; 7:431. [PMID: 28348377 PMCID: PMC5427978 DOI: 10.1038/s41598-017-00275-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 02/15/2017] [Indexed: 02/05/2023] Open
Abstract
Neonatal brain is particularly vulnerable to pathological levels of bilirubin which elevates and overloads intracellular Ca2+, leading to neurotoxicity. However, how voltage-gated calcium channels (VGCCs) are functionally involved in excess calcium influx remains unknown. By performing voltage-clamp recordings from bushy cells in the ventral cochlear nucleus (VCN) in postnatal rat pups (P4-17), we found the total calcium current density was more than doubled over P4-17, but the relative weight of VGCC subtypes changed dramatically, being relatively equal among T, L, N, P/Q and R-type at P4-6 to predominantly L, N, R over T and P/Q at P15-17. Surprisingly, acute administration of bilirubin augmented the VGCC currents specifically mediated by high voltage-activated (HVA) P/Q-type calcium currents. This augment was attenuated by intracellular loading of Ca2+ buffer EGTA or calmodulin inhibitory peptide. Our findings indicate that acute exposure to bilirubin increases VGCC currents, primarily by targeting P/Q-type calcium channels via Ca2+ and calmodulin dependent mechanisms to overwhelm neurons with excessive Ca2+. Since P/Q-subtype calcium channels are more prominent in neonatal neurons (e.g. P4-6) than later stages, we suggest this subtype-specific enhancement of P/Q-type Ca2+ currents likely contributes to the early neuronal vulnerability to hyperbilirubinemia in auditory and other brain regions.
Collapse
|
11
|
Briot J, Tétreault MP, Bourdin B, Parent L. Inherited Ventricular Arrhythmias: The Role of the Multi-Subunit Structure of the L-Type Calcium Channel Complex. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 966:55-64. [PMID: 28315127 DOI: 10.1007/5584_2016_186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The normal heartbeat is conditioned by transient increases in the intracellular free Ca2+ concentration. Ca2+ influx in cardiomyocytes is regulated by the activity of the heteromeric L-type voltage-activated CaV1.2 channel. A complex network of interactions between the different proteins forming the ion channel supports the kinetics and the activation gating of the Ca2+ influx. Alterations in the biophysical and biochemical properties or in the biogenesis in any of these proteins can lead to serious disturbances in the cardiac rhythm. The multi-subunit nature of the channel complex is better comprehended by examining the high-resolution three-dimensional structure of the closely related CaV1.1 channel. The architectural map identifies precise interaction loci between the different subunits and paves the way for elucidating the mechanistic basis for the regulation of Ca2+ balance in cardiac myocytes under physiological and pathological conditions.
Collapse
Affiliation(s)
- Julie Briot
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Institut Cardiologie de Montréal, Université de Montréal, 5000 Bélanger, Montréal, QC, H1T 1C8, Canada
| | - Marie-Philippe Tétreault
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Institut Cardiologie de Montréal, Université de Montréal, 5000 Bélanger, Montréal, QC, H1T 1C8, Canada
| | - Benoîte Bourdin
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Institut Cardiologie de Montréal, Université de Montréal, 5000 Bélanger, Montréal, QC, H1T 1C8, Canada
| | - Lucie Parent
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Institut Cardiologie de Montréal, Université de Montréal, 5000 Bélanger, Montréal, QC, H1T 1C8, Canada.
| |
Collapse
|
12
|
L-Type Calcium Channels Modulation by Estradiol. Mol Neurobiol 2016; 54:4996-5007. [PMID: 27525676 DOI: 10.1007/s12035-016-0045-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 08/08/2016] [Indexed: 01/29/2023]
Abstract
Voltage-gated calcium channels are key regulators of brain function, and their dysfunction has been associated with multiple conditions and neurodegenerative diseases because they couple membrane depolarization to the influx of calcium-and other processes such as gene expression-in excitable cells. L-type calcium channels, one of the three major classes and probably the best characterized of the voltage-gated calcium channels, act as an essential calcium binding proteins with a significant biological relevance. It is well known that estradiol can activate rapidly brain signaling pathways and modulatory/regulatory proteins through non-genomic (or non-transcriptional) mechanisms, which lead to an increase of intracellular calcium that activate multiple kinases and signaling cascades, in the same way as L-type calcium channels responses. In this context, estrogens-L-type calcium channels signaling raises intracellular calcium levels and activates the same signaling cascades in the brain probably through estrogen receptor-independent modulatory mechanisms. In this review, we discuss the available literature on this area, which seems to suggest that estradiol exerts dual effects/modulation on these channels in a concentration-dependent manner (as a potentiator of these channels in pM concentrations and as an inhibitor in nM concentrations). Indeed, estradiol may orchestrate multiple neurotrophic responses, which open a new avenue for the development of novel estrogen-based therapies to alleviate different neuropathologies. We also highlight that it is essential to determine through computational and/or experimental approaches the interaction between estradiol and L-type calcium channels to assist these developments, which is an interesting area of research that deserves a closer look in future biomedical research.
Collapse
|
13
|
Ben-Johny M, Dick IE, Sang L, Limpitikul WB, Kang PW, Niu J, Banerjee R, Yang W, Babich JS, Issa JB, Lee SR, Namkung H, Li J, Zhang M, Yang PS, Bazzazi H, Adams PJ, Joshi-Mukherjee R, Yue DN, Yue DT. Towards a Unified Theory of Calmodulin Regulation (Calmodulation) of Voltage-Gated Calcium and Sodium Channels. Curr Mol Pharmacol 2016; 8:188-205. [PMID: 25966688 DOI: 10.2174/1874467208666150507110359] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 01/29/2015] [Accepted: 04/20/2015] [Indexed: 12/13/2022]
Abstract
Voltage-gated Na and Ca(2+) channels represent two major ion channel families that enable myriad biological functions including the generation of action potentials and the coupling of electrical and chemical signaling in cells. Calmodulin regulation (calmodulation) of these ion channels comprises a vital feedback mechanism with distinct physiological implications. Though long-sought, a shared understanding of the channel families remained elusive for two decades as the functional manifestations and the structural underpinnings of this modulation often appeared to diverge. Here, we review recent advancements in the understanding of calmodulation of Ca(2+) and Na channels that suggest a remarkable similarity in their regulatory scheme. This interrelation between the two channel families now paves the way towards a unified mechanistic framework to understand vital calmodulin-dependent feedback and offers shared principles to approach related channelopathic diseases. An exciting era of synergistic study now looms.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - David T Yue
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, USA.
| |
Collapse
|
14
|
Voltage-gated calcium channels: Determinants of channel function and modulation by inorganic cations. Prog Neurobiol 2015; 129:1-36. [PMID: 25817891 DOI: 10.1016/j.pneurobio.2014.12.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 12/15/2014] [Accepted: 12/27/2014] [Indexed: 11/20/2022]
Abstract
Voltage-gated calcium channels (VGCCs) represent a key link between electrical signals and non-electrical processes, such as contraction, secretion and transcription. Evolved to achieve high rates of Ca(2+)-selective flux, they possess an elaborate mechanism for selection of Ca(2+) over foreign ions. It has been convincingly linked to competitive binding in the pore, but the fundamental question of how this is reconcilable with high rates of Ca(2+) transfer remains unanswered. By virtue of their similarity to Ca(2+), polyvalent cations can interfere with the function of VGCCs and have proven instrumental in probing the mechanisms underlying selective permeation. Recent emergence of crystallographic data on a set of Ca(2+)-selective model channels provides a structural framework for permeation in VGCCs, and warrants a reconsideration of their diverse modulation by polyvalent cations, which can be roughly separated into three general mechanisms: (I) long-range interactions with charged regions on the surface, affecting the local potential sensed by the channel or influencing voltage-sensor movement by repulsive forces (electrostatic effects), (II) short-range interactions with sites in the ion-conducting pathway, leading to physical obstruction of the channel (pore block), and in some cases (III) short-range interactions with extracellular binding sites, leading to non-electrostatic modifications of channel gating (allosteric effects). These effects, together with the underlying molecular modifications, provide valuable insights into the function of VGCCs, and have important physiological and pathophysiological implications. Allosteric suppression of some of the pore-forming Cavα1-subunits (Cav2.3, Cav3.2) by Zn(2+) and Cu(2+) may play a major role for the regulation of excitability by endogenous transition metal ions. The fact that these ions can often traverse VGCCs can contribute to the detrimental intracellular accumulation of metal ions following excessive release of endogenous Cu(2+) and Zn(2+) or exposure to non-physiological toxic metal ions.
Collapse
|
15
|
Ben-Johny M, Yue DT. Calmodulin regulation (calmodulation) of voltage-gated calcium channels. ACTA ACUST UNITED AC 2014; 143:679-92. [PMID: 24863929 PMCID: PMC4035741 DOI: 10.1085/jgp.201311153] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Calmodulin regulation (calmodulation) of the family of voltage-gated CaV1-2 channels comprises a prominent prototype for ion channel regulation, remarkable for its powerful Ca(2+) sensing capabilities, deep in elegant mechanistic lessons, and rich in biological and therapeutic implications. This field thereby resides squarely at the epicenter of Ca(2+) signaling biology, ion channel biophysics, and therapeutic advance. This review summarizes the historical development of ideas in this field, the scope and richly patterned organization of Ca(2+) feedback behaviors encompassed by this system, and the long-standing challenges and recent developments in discerning a molecular basis for calmodulation. We conclude by highlighting the considerable synergy between mechanism, biological insight, and promising therapeutics.
Collapse
Affiliation(s)
- Manu Ben-Johny
- Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| |
Collapse
|
16
|
Tricco AC, Cogo E, Angeliki VA, Soobiah C, Hutton B, Hemmelgarn BR, Moher D, Finkelstein Y, Straus SE. Comparative safety of anti-epileptic drugs among infants and children exposed in utero or during breastfeeding: protocol for a systematic review and network meta-analysis. Syst Rev 2014; 3:68. [PMID: 24964932 PMCID: PMC4086277 DOI: 10.1186/2046-4053-3-68] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 06/17/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Epilepsy affects about 1% of the general population. Anti-epileptic drugs (AEDs) prevent or terminate seizures in individuals with epilepsy. Pregnant women with epilepsy may continue taking AEDs. Many of these agents cross the placenta and increase the risk of major congenital malformations, early cognitive and developmental delays, and infant mortality. We aim to evaluate the comparative safety of AEDs approved for chronic use in Canada when administered to pregnant and breastfeeding women and the effects on their infants and children through a systematic review and network meta-analysis. METHODS Studies examining the effects of AEDs administered to pregnant and breastfeeding women regardless of indication (e.g., epilepsy, migraine, pain, psychiatric disorders) on their infants and children will be included. We will include randomized clinical trials (RCTs), quasi-RCTs, non-RCTs, controlled before-after, interrupted time series, cohort, registry, and case-control studies. The main literature search will be executed in MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials. We will seek unpublished literature through searches of trial protocol registries and conference abstracts. The literature search results screening, data abstraction, and risk of bias appraisal will be performed by two individuals, independently. Conflicts will be resolved through discussion. The risk of bias of experimental and quasi-experimental studies will be appraised using the Cochrane Effective Practice and Organization of Care Risk-of-Bias tool, methodological quality of observational studies will be appraised using the Newcastle-Ottawa Scale, and quality of reporting of safety outcomes will be conducted using the McMaster Quality Assessment Scale of Harms (McHarm) tool. If feasible and appropriate, we will conduct random effects meta-analysis. Network meta-analysis will be considered for outcomes that fulfill network meta-analysis assumptions.The primary outcome is major congenital malformations (overall and by specific types), while secondary outcomes include fetal loss/miscarriage, minor congenital malformations (overall and by specific types), cognitive development, psychomotor development, small for gestational age, preterm delivery, and neonatal seizures. DISCUSSION Our systematic review will address safety concerns regarding the use of AEDs during pregnancy and breastfeeding. Our results will be useful to healthcare providers, policy-makers, and women of childbearing age who are taking anti-epileptic medications. SYSTEMATIC REVIEW REGISTRATION PROSPERO CRD42014008925.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - Sharon E Straus
- Li Ka Shing Knowledge Institute, St, Michael's Hospital, 209 Victoria Street, East Building, Toronto, Ontario M5B 1 T8, Canada.
| |
Collapse
|
17
|
Kline CF, Scott J, Curran J, Hund TJ, Mohler PJ. Ankyrin-B regulates Cav2.1 and Cav2.2 channel expression and targeting. J Biol Chem 2014; 289:5285-95. [PMID: 24394417 DOI: 10.1074/jbc.m113.523639] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
N-type and P/Q-type calcium channels are documented players in the regulation of synaptic function; however, the mechanisms underlying their expression and cellular targeting are poorly understood. Ankyrin polypeptides are essential for normal integral membrane protein expression in a number of cell types, including neurons, cardiomyocytes, epithelia, secretory cells, and erythrocytes. Ankyrin dysfunction has been linked to defects in integral protein expression, abnormal cellular function, and disease. Here, we demonstrate that ankyrin-B associates with Cav2.1 and Cav2.2 in cortex, cerebellum, and brain stem. Additionally, using in vitro and in vivo techniques, we demonstrate that ankyrin-B, via its membrane-binding domain, associates with a highly conserved motif in the DII/III loop domain of Cav2.1 and Cav2.2. Further, we demonstrate that this domain is necessary for proper targeting of Cav2.1 and Cav2.2 in a heterologous system. Finally, we demonstrate that mutation of a single conserved tyrosine residue in the ankyrin-binding motif of both Cav2.1 (Y797E) and Cav2.2 (Y788E) results in loss of association with ankyrin-B in vitro and in vivo. Collectively, our findings identify an interaction between ankyrin-B and both Cav2.1 and Cav2.2 at the amino acid level that is necessary for proper Cav2.1 and Cav2.2 targeting in vivo.
Collapse
|
18
|
Hiriart M, Velasco M, Larqué C, Diaz-Garcia CM. Metabolic Syndrome and Ionic Channels in Pancreatic Beta Cells. THE PANCREATIC BETA CELL 2014; 95:87-114. [DOI: 10.1016/b978-0-12-800174-5.00004-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
19
|
Demers-Giroux PO, Bourdin B, Sauvé R, Parent L. Cooperative activation of the T-type CaV3.2 channel: interaction between Domains II and III. J Biol Chem 2013; 288:29281-93. [PMID: 23970551 PMCID: PMC3795230 DOI: 10.1074/jbc.m113.500975] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 08/02/2013] [Indexed: 12/28/2022] Open
Abstract
T-type CaV3 channels are important mediators of Ca(2+) entry near the resting membrane potential. Little is known about the molecular mechanisms responsible for channel activation. Homology models based upon the high-resolution structure of bacterial NaV channels predict interaction between the S4-S5 helix of Domain II (IIS4-S5) and the distal S6 pore region of Domain II (IIS6) and Domain III (IIIS6). Functional intra- and inter-domain interactions were investigated with a double mutant cycle analysis. Activation gating and channel kinetics were measured for 47 single mutants and 20 pairs of mutants. Significant coupling energies (ΔΔG(interact) ≥ 1.5 kcal mol(-1)) were measured for 4 specific pairs of mutants introduced between IIS4-S5 and IIS6 and between IIS4-S5 and IIIS6. In agreement with the computer based models, Thr-911 in IIS4-S5 was functionally coupled with Ile-1013 in IIS6 during channel activation. The interaction energy was, however, found to be stronger between Val-907 in IIS4-S5 and Ile-1013 in IIS6. In addition Val-907 was significantly coupled with Asn-1548 in IIIS6 but not with Asn-1853 in IVS6. Altogether, our results demonstrate that the S4-S5 and S6 helices from adjacent domains are energetically coupled during the activation of a low voltage-gated T-type CaV3 channel.
Collapse
Affiliation(s)
- Pierre-Olivier Demers-Giroux
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Benoîte Bourdin
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Rémy Sauvé
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Lucie Parent
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| |
Collapse
|
20
|
Martín V, Vale C, Bondu S, Thomas OP, Vieytes MR, Botana LM. Differential effects of crambescins and crambescidin 816 in voltage-gated sodium, potassium and calcium channels in neurons. Chem Res Toxicol 2013; 26:169-78. [PMID: 23270282 DOI: 10.1021/tx3004483] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Crambescins and crambescidins are two families of guanidine alkaloids from the marine sponge Crambe crambe. Although very little information about their biological effect has been reported, it is known that crambescidin 816 (Cramb816) blocks calcium channels in a neuroblastoma X glioma cell line. Taking this into account, and the fact that ion channels are frequent targets for natural toxins, we examined the effect of Cramb816 and three compounds from the crambescin family, norcrambescin A2 (NcrambA2), crambescin A2 (CrambA2), and crambescin C1 (CrambC1), in the main voltage-dependent ion channels in neurons: sodium, potassium, and calcium channels. Electrophysiological recordings of voltage gated sodium, potassium, and calcium currents, in the presence of these guanidine alkaloids, were performed in cortical neurons from embryonic mice. Different effects were discovered: crambescins inhibited K(+) currents with the following potency: NcrambA2 > CrambC1 > CrambA2, while Cramb816 lacked an effect. Only CrambC1 and Cramb816 partially blocked Na(+) total current. However, Cramb816 partially blocked Ca(2+) , while NcrambA2 did not. Since the blocking effect of Cramb816 on calcium currents has not been previously reported in detail, we further pharmacologically isolated the two main fractions of HVA Ca(2+) channels in neurons and investigated the Cramb816 effect on them. Here, we revealed that Cav1 or L-type calcium channels are the main target for Cramb816. These two families of guanidine alkaloids clearly showed a structure-activity relationship with the crambescins acting on voltage-gated potassium channels, while Cramb816 blocks the voltage-gated calcium channel Cav1 with higher potency than nifedipine. The novel evidence that Cramb816 partially blocked CaV and NaV channels in neurons suggests that this compound might be involved in decreasing the neurotransmitter release and synaptic transmission in the central nervous system. The findings presented here provide the first detailed approach on the different effects of crambescin and crambescidin compounds in voltage-gated sodium, potassium, and calcium channels in neurons and thus provide a basis for future studies.
Collapse
Affiliation(s)
- Víctor Martín
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela , Lugo, Spain
| | | | | | | | | | | |
Collapse
|
21
|
Harries AM, Sandhu M, Spacey SD, Aly MM, Honey CR. Unilateral Pallidal Deep Brain Stimulation in a Patient with Dystonia Secondary to Episodic Ataxia Type 2. Stereotact Funct Neurosurg 2013; 91:233-5. [DOI: 10.1159/000345265] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Accepted: 10/15/2012] [Indexed: 11/19/2022]
|
22
|
The proximal C-terminus of α1C subunits is necessary for junctional membrane targeting of cardiac L-type calcium channels. Biochem J 2012; 448:221-31. [DOI: 10.1042/bj20120773] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In cardiac myocytes, LTCCs (L-type calcium channels) form a functional signalling complex with ryanodine receptors at the JM (junctional membrane). Although the specific localization of LTCCs to the JM is critical for excitation–contraction coupling, their targeting mechanism is unclear. Transient transfection of GFP (green fluorescent protein)–α1S or GFP–α1C, but not P/Q-type calcium channel α1A, in dysgenic (α1S-null) GLT myotubes results in correct targeting of these LTCCs to the JMs and restoration of action-potential-induced Ca2+ transients. To identify the sequences of α1C responsible for JM targeting, we generated a range of α1C–α1A chimaeras, deletion mutants and alanine substitution mutants and studied their targeting properties in GLT myotubes. The results revealed that amino acids L1681QAGLRTL1688 and P1693EIRRAIS1700, predicted to form two adjacent α-helices in the proximal C-terminus, are necessary for the JM targeting of α1C. The efficiency of restoration of action-potential-induced Ca2+ transients in GLT myotubes was significantly decreased by mutations in the targeting motif. JM targeting was not disrupted by the distal C-terminus of α1C which binds to the second α-helix. Therefore we have identified a new structural motif in the C-terminus of α1C that mediates the targeting of cardiac LTCCs to JMs independently of the interaction between proximal and distal C-termini of α1C.
Collapse
|
23
|
Nikoletopoulou V, Tavernarakis N. Calcium homeostasis in aging neurons. Front Genet 2012; 3:200. [PMID: 23060904 PMCID: PMC3462315 DOI: 10.3389/fgene.2012.00200] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 09/19/2012] [Indexed: 11/13/2022] Open
Abstract
The nervous system becomes increasingly vulnerable to insults and prone to dysfunction during aging. Age-related decline of neuronal function is manifested by the late onset of many neurodegenerative disorders, as well as by reduced signaling and processing capacity of individual neuron populations. Recent findings indicate that impairment of Ca(2+) homeostasis underlies the increased susceptibility of neurons to damage, associated with the aging process. However, the impact of aging on Ca(2+) homeostasis in neurons remains largely unknown. Here, we survey the molecular mechanisms that mediate neuronal Ca(2+) homeostasis and discuss the impact of aging on their efficacy. To address the question of how aging impinges on Ca(2+) homeostasis, we consider potential nodes through which mechanisms regulating Ca(2+) levels interface with molecular pathways known to influence the process of aging and senescent decline. Delineation of this crosstalk would facilitate the development of interventions aiming to fortify neurons against age-associated functional deterioration and death by augmenting Ca(2+) homeostasis.
Collapse
Affiliation(s)
- Vassiliki Nikoletopoulou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas Heraklion, Crete, Greece
| | | |
Collapse
|
24
|
Shakeri B, Bourdin B, Demers-Giroux PO, Sauvé R, Parent L. A quartet of leucine residues in the guanylate kinase domain of CaVβ determines the plasma membrane density of the CaV2.3 channel. J Biol Chem 2012; 287:32835-47. [PMID: 22846999 DOI: 10.1074/jbc.m112.387233] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ca(V)β subunits are formed by a Src homology 3 domain and a guanylate kinase-like (GK) domain connected through a variable HOOK domain. Complete deletion of the Src homology 3 domain (75 residues) as well as deletion of the HOOK domain (47 residues) did not alter plasma membrane density of Ca(V)2.3 nor its typical activation gating. In contrast, six-residue deletions in the GK domain disrupted cell surface trafficking and functional expression of Ca(V)2.3. Mutations of residues known to carry nanomolar affinity binding in the GK domain of Ca(V)β (P175A, P179A, M195A, M196A, K198A, S295A, R302G, R307A, E339G, N340G, and A345G) did not significantly alter cell surface targeting or gating modulation of Ca(V)2.3. Nonetheless, mutations of a quartet of leucine residues (either single or multiple mutants) in the α3, α6, β10, and α9 regions of the GK domain were found to significantly impair cell surface density of Ca(V)2.3 channels. Furthermore, the normalized protein density of Ca(V)2.3 was nearly abolished with the quadruple Ca(V)β3 Leu mutant L200G/L303G/L337G/L342G. Altogether, our observations suggest that the four leucine residues in Ca(V)β3 form a hydrophobic pocket surrounding key residues in the α-interacting domain of Ca(V)2.3. This interaction appears to play an essential role in conferring Ca(V)β-induced modulation of the protein density of Ca(V)α1 subunits in Ca(V)2 channels.
Collapse
Affiliation(s)
- Behzad Shakeri
- Département de Physiologie and the Membrane Protein Research Group, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | | | | | | | | |
Collapse
|
25
|
Weber JT. Altered calcium signaling following traumatic brain injury. Front Pharmacol 2012; 3:60. [PMID: 22518104 PMCID: PMC3324969 DOI: 10.3389/fphar.2012.00060] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Accepted: 03/24/2012] [Indexed: 01/10/2023] Open
Abstract
Cell death and dysfunction after traumatic brain injury (TBI) is caused by a primary phase, related to direct mechanical disruption of the brain, and a secondary phase which consists of delayed events initiated at the time of the physical insult. Arguably, the calcium ion contributes greatly to the delayed cell damage and death after TBI. A large, sustained influx of calcium into cells can initiate cell death signaling cascades, through activation of several degradative enzymes, such as proteases and endonucleases. However, a sustained level of intracellular free calcium is not necessarily lethal, but the specific route of calcium entry may couple calcium directly to cell death pathways. Other sources of calcium, such as intracellular calcium stores, can also contribute to cell damage. In addition, calcium-mediated signal transduction pathways in neurons may be perturbed following injury. These latter types of alterations may contribute to abnormal physiology in neurons that do not necessarily die after a traumatic episode. This review provides an overview of experimental evidence that has led to our current understanding of the role of calcium signaling in death and dysfunction following TBI.
Collapse
Affiliation(s)
- John T. Weber
- School of Pharmacy and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of NewfoundlandSt. John’s, NL, Canada
| |
Collapse
|
26
|
Abstract
The autosomal dominant spinocerebellar ataxias (SCA) are a genetically heterogeneous group of neurodegenerative disorders characterized by progressive motor incoordination, in some cases with ataxia alone and in others in association with additional progressive neurological deficits. Spinocerebellar ataxia type 6 (SCA6) is the prototype of a pure cerebellar ataxia, associated with a severe form of progressive ataxia and cerebellar dysfunction. SCA6, originally classified as such by Zhuchenko et al. (1997), is caused by a CAG repeat expansion in the CACNA1A gene which encodes the α1A subunit of the P/Q-type voltage-gated calcium channel. SCA6 is one of ten polyglutamine-encoding CAG nucleotide repeat expansion disorders comprising other neurodegenerative disorders such as Huntington's disease. The present review describes clinical, genetic, and pathological manifestations associated with this illness. Currently, there is no treatment for this neurodegenerative disease. Successful therapeutic strategies must target a valid pathological mechanism; thus, understanding the underlying mechanisms of disease is crucial to finding a proper treatment. Hence, this chapter will discuss as well the molecular mechanisms possibly associated with SCA6 pathology and their implication for the development of future treatment.
Collapse
Affiliation(s)
- Ana Solodkin
- Department of Neurology, University of Chicago Medical Center, Chicago, IL 606337, USA.
| | | |
Collapse
|
27
|
Abstract
Voltage-gated calcium (Ca(2+)) channels are key transducers of membrane potential changes into intracellular Ca(2+) transients that initiate many physiological events. There are ten members of the voltage-gated Ca(2+) channel family in mammals, and they serve distinct roles in cellular signal transduction. The Ca(V)1 subfamily initiates contraction, secretion, regulation of gene expression, integration of synaptic input in neurons, and synaptic transmission at ribbon synapses in specialized sensory cells. The Ca(V)2 subfamily is primarily responsible for initiation of synaptic transmission at fast synapses. The Ca(V)3 subfamily is important for repetitive firing of action potentials in rhythmically firing cells such as cardiac myocytes and thalamic neurons. This article presents the molecular relationships and physiological functions of these Ca(2+) channel proteins and provides information on their molecular, genetic, physiological, and pharmacological properties.
Collapse
Affiliation(s)
- William A Catterall
- Department of Pharmacology, University of Washington, Seattle, Washington 98195-7280, USA.
| |
Collapse
|
28
|
Wall-Lacelle S, Hossain MI, Sauvé R, Blunck R, Parent L. Double mutant cycle analysis identified a critical leucine residue in the IIS4S5 linker for the activation of the Ca(V)2.3 calcium channel. J Biol Chem 2011; 286:27197-205. [PMID: 21652722 DOI: 10.1074/jbc.m111.237412] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mutations in distal S6 were shown to significantly alter the stability of the open state of Ca(V)2.3 (Raybaud, A., Baspinar, E. E., Dionne, F., Dodier, Y., Sauvé, R., and Parent, L. (2007) J. Biol. Chem. 282, 27944-27952). By analogy with K(V) channels, we tested the hypothesis that channel activation involves electromechanical coupling between S6 and the S4S5 linker in Ca(V)2.3. Among the 11 positions tested in the S4S5 linker of domain II, mutations of the leucine residue at position 596 were found to destabilize significantly the closed state with a -50 mV shift in the activation potential and a -20 mV shift in its charge-voltage relationship as compared with Ca(V)2.3 wt. A double mutant cycle analysis was performed by introducing pairs of glycine residues between S4S5 and S6 of Domain II. Strong coupling energies (ΔΔG(interact) > 2 kcal mol(-1)) were measured for the activation gating of 12 of 39 pairs of mutants. Leu-596 (IIS4S5) was strongly coupled with distal residues in IIS6 from Leu-699 to Asp-704. In particular, the double mutant L596G/I701G showed strong cooperativity with a ΔΔG(interact) ≈6 kcal mol(-1) suggesting that both positions contribute to the activation gating of the channel. Altogether, our results highlight the role of a leucine residue in S4S5 and provide the first series of evidence that the IIS4S5 and IIS6 regions are energetically coupled during the activation of a voltage-gated Ca(V) channel.
Collapse
Affiliation(s)
- Sébastien Wall-Lacelle
- Department of Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | | | | | | | | |
Collapse
|
29
|
Pasqualoni E, Aubart F, Brihaye B, Sacré K, Maisonobe T, Laissy JP, Lidove O, Papo T. Lambert–Eaton Myasthenic syndrome and follicular thymic hyperplasia in systemic lupus erythematosus. Lupus 2011; 20:745-8. [DOI: 10.1177/0961203310393769] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- E Pasqualoni
- Department of Internal Medicine, Bichat-Claude Bernard Hospital, Paris-Diderot University, Paris, France
| | - F Aubart
- Department of Neurophysiology, Pitié-Salpetrière Hospital, Paris, France
| | - B Brihaye
- Department of Internal Medicine, Bichat-Claude Bernard Hospital, Paris-Diderot University, Paris, France
| | - K Sacré
- Department of Internal Medicine, Bichat-Claude Bernard Hospital, Paris-Diderot University, Paris, France
| | - T Maisonobe
- Department of Neurophysiology, Pitié-Salpetrière Hospital, Paris, France
| | - J-P Laissy
- Department of Radiology, Bichat-Claude Bernard Hospital, Paris-Diderot University, Paris, France
| | - O Lidove
- Department of Internal Medicine, Bichat-Claude Bernard Hospital, Paris-Diderot University, Paris, France
| | - T Papo
- Department of Internal Medicine, Bichat-Claude Bernard Hospital, Paris-Diderot University, Paris, France
| |
Collapse
|
30
|
Calcium channel subtypes for cholinergic and nonadrenergic noncholinergic neurotransmission in isolated guinea pig trachea. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2010; 382:419-32. [PMID: 20820758 DOI: 10.1007/s00210-010-0556-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Accepted: 08/18/2010] [Indexed: 10/19/2022]
Abstract
The Ca(2+) channel subtypes in the neurotransmission of isolated guinea pig trachea were elucidated by monitoring the effects of specific Ca(2+) channel blockers on cholinergic contractions and nonadrenergic noncholinergic (NANC) relaxation elicited by electrical field stimulation (EFS). In isolated guinea pig trachea, cholinergic contractile responses to low- and high-frequency EFS were inhibited by the selective N-type calcium channel blocker, ω-conotoxin MVIIA. ω-Agatoxin IVA (a selective P-type blocker), ω-conotoxin MVIIC (a nonselective N-, Q-, and P-type blocker), and nifedipine (a selective L-type blocker) were ineffective, whereas Ni(2+) (a T- and R-type blocker) facilitated cholinergic contractions and produced a late contracture when its concentration exceeded 30 μM. The more the concentration of Ni(2+) increased, the greater the number of incidences and the late contracture areas which occurred. Late contracture did not seem to be due to the effects of acetylcholine, tachykinins, or other polypeptides, but disappeared in the absence of indomethacin. The NANC relaxant responses elicited by the low- and high-frequency EFS were inhibited by ω-conotoxin MVIIA or Ni(2+), but unaffected by ω-Agatoxin IVA, ω-conotoxin MVIIC, and nifedipine. In the absence of indomethacin, Ni(2+) did not alter the ω-conotoxin MVIIA (100 nM)-resistant component of cholinergic contraction, but significantly further inhibited that of NANC relaxation. These results suggest that in isolated guinea pig trachea, cholinergic contraction is regulated by N-type calcium channels which may mask T- and R-type calcium channels and may be co-modulated by both, while NANC relaxation is mainly and independently controlled by N-, T-, and R-type calcium channels.
Collapse
|
31
|
Bourdin B, Marger F, Wall-Lacelle S, Schneider T, Klein H, Sauvé R, Parent L. Molecular determinants of the CaVbeta-induced plasma membrane targeting of the CaV1.2 channel. J Biol Chem 2010; 285:22853-63. [PMID: 20478999 DOI: 10.1074/jbc.m110.111062] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ca(V)beta subunits modulate cell surface expression and voltage-dependent gating of high voltage-activated (HVA) Ca(V)1 and Ca(V)2 alpha1 subunits. High affinity Ca(V)beta binding onto the so-called alpha interaction domain of the I-II linker of the Ca(V)alpha1 subunit is required for Ca(V)beta modulation of HVA channel gating. It has been suggested, however, that Ca(V)beta-mediated plasma membrane targeting could be uncoupled from Ca(V)beta-mediated modulation of channel gating. In addition to Ca(V)beta, Ca(V)alpha2delta and calmodulin have been proposed to play important roles in HVA channel targeting. Indeed we show that co-expression of Ca(V)alpha2delta caused a 5-fold stimulation of the whole cell currents measured with Ca(V)1.2 and Ca(V)beta3. To gauge the synergetic role of auxiliary subunits in the steady-state plasma membrane expression of Ca(V)1.2, extracellularly tagged Ca(V)1.2 proteins were quantified using fluorescence-activated cell sorting analysis. Co-expression of Ca(V)1.2 with either Ca(V)alpha2delta, calmodulin wild type, or apocalmodulin (alone or in combination) failed to promote the detection of fluorescently labeled Ca(V)1.2 subunits. In contrast, co-expression with Ca(V)beta3 stimulated plasma membrane expression of Ca(V)1.2 by a 10-fold factor. Mutations within the alpha interaction domain of Ca(V)1.2 or within the nucleotide kinase domain of Ca(V)beta3 disrupted the Ca(V)beta3-induced plasma membrane targeting of Ca(V)1.2. Altogether, these data support a model where high affinity binding of Ca(V)beta to the I-II linker of Ca(V)alpha1 largely accounts for Ca(V)beta-induced plasma membrane targeting of Ca(V)1.2.
Collapse
Affiliation(s)
- Benoîte Bourdin
- Institute of Neurophysiology and Center for Molecular Medicine, Cologne University, D-50931 Cologne, Germany
| | | | | | | | | | | | | |
Collapse
|
32
|
Kamide K, Yang J, Matayoshi T, Takiuchi S, Horio T, Yoshii M, Miwa Y, Yasuda H, Yoshihara F, Nakamura S, Nakahama H, Miyata T, Kawano Y. Genetic polymorphisms of L-type calcium channel alpha1C and alpha1D subunit genes are associated with sensitivity to the antihypertensive effects of L-type dihydropyridine calcium-channel blockers. Circ J 2009; 73:732-40. [PMID: 19225208 DOI: 10.1253/circj.cj-08-0761] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The response of blood pressure (BP) to L-type dihydropyridine calcium-channel blockers (dCCBs) differs among individuals. METHODS AND RESULTS A pharmacogenomic analysis was undertaken in 161 patients with essential hypertension who were treated with dCCBs to study whether genetic polymorphisms of the calcium channel alpha1C and alpha1D subunit genes, CACNA1C and CACNA1D, are associated with the antihypertensive effects of dCCBs. Responders were defined as those in whom systolic BP (SBP) was lowered by more than 20 mmHg or diastolic BP (DBP) was lowered by more than 10 mmHg after treatment with dCCBs. Eleven sequence-proven polymorphisms of CACNA1C and 5 common polymorphisms of CACNA1D chosen from a public database were subjected to genotypic analysis. The comparison of polymorphism prevalence between responders and nonresponders showed significant differences in CACNA1D rs312481G>A and rs3774426C>T, and in CACNA1C 527974G>A. There were significant differences in SBP or DBP between alleles in these single nucleotide polymorphisms (SNPs). A much more significant reduction in BP was observed for the combined presence of these SNPs. CONCLUSIONS Three SNPs in CACNA1D or CACNA1C are genetic polymorphisms conferring sensitivity to the antihypertensive effects of L-type dCCBs in patients with hypertension. The BP reduction by L-type dCCBs might be predicted by evaluating these polymorphisms.
Collapse
Affiliation(s)
- Kei Kamide
- Division of Hypertension and Nephrology, Research Institute, National Cardiovascular Center, Suita, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
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]
|
34
|
Loss of skeletal muscle strength by ablation of the sarcoplasmic reticulum protein JP45. Proc Natl Acad Sci U S A 2007; 104:20108-13. [PMID: 18077436 DOI: 10.1073/pnas.0707389104] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Skeletal muscle constitutes approximately 40% of the human body mass, and alterations in muscle mass and strength may result in physical disability. Therefore, the elucidation of the factors responsible for muscle force development is of paramount importance. Excitation-contraction coupling (ECC) is a process during which the skeletal muscle surface membrane is depolarized, causing a transient release of calcium from the sarcoplasmic reticulum that activates the contractile proteins. The ECC machinery is complex, and the functional role of many of its protein components remains elusive. This study demonstrates that deletion of the gene encoding the sarcoplasmic reticulum protein JP45 results in decreased muscle strength in young mice. Specifically, this loss of muscle strength in JP45 knockout mice is caused by decreased functional expression of the voltage-dependent Ca(2+) channel Ca(v)1.1, which is the molecule that couples membrane depolarization and calcium release from the sarcoplasmic reticulum. These results point to JP45 as one of the molecules involved in the development or maintenance of skeletal muscle strength.
Collapse
|
35
|
Raybaud A, Baspinar EE, Dionne F, Dodier Y, Sauvé R, Parent L. The Role of Distal S6 Hydrophobic Residues in the Voltage-dependent Gating of CaV2.3 Channels. J Biol Chem 2007; 282:27944-52. [PMID: 17660294 DOI: 10.1074/jbc.m703895200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The hydrophobic locus VAVIM is conserved in the S6 transmembrane segment of domain IV (IVS6) in Ca(V)1 and Ca(V)2 families. Herein we show that glycine substitution of the VAVIM motif in Ca(V)2.3 produced whole cell currents with inactivation kinetics that were either slower (A1719G approximately V1720G), similar (V1718G), or faster (I1721G approximately M1722G) than the wild-type channel. The fast kinetics of I1721G were observed with a approximately +10 mV shift in its voltage dependence of activation (E(0.5,act)). In contrast, the slow kinetics of A1719G and V1720G were accompanied by a significant shift of approximately -20 mV in their E(0.5,act) indicating that the relative stability of the channel closed state was decreased in these mutants. Glycine scan performed with Val (349) in IS6, Ile(701) in IIS6, and Leu(1420) in IIIS6 at positions predicted to face Val(1720) in IVS6 also produced slow inactivating currents with hyperpolarizing shifts in the activation and inactivation potentials, again pointing out a decrease in the stability of the channel closed state. Mutations to other hydrophobic residues at these positions nearly restored the channel gating. Altogether these data indicate that residues at positions equivalent to 1720 exert a critical control upon the relative stability of the channel closed and open states and more specifically, that hydrophobic residues at these positions promote the channel closed state. We discuss a three-dimensional homology model of Ca(V)2.3 based upon Kv1.2 where hydrophobic residues at positions facing Val(1720) in IS6, IIS6, and IIIS6 play a critical role in stabilizing the closed state in Ca(V)2.3.
Collapse
Affiliation(s)
- Alexandra Raybaud
- Département de Physiologie and the Membrane Protein Research Group, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | | | | | | | | | | |
Collapse
|
36
|
Abstract
Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disorder caused by abnormal expansions of a trinucleotide CAG repeat in exon 47 of the CACNA1A gene, which encodes the alpha1A subunit of the P/Q-type voltage-gated calcium channel. The CAG repeat expansion is translated into an elongated polyglutamine tract in the carboxyl terminus of the alpha1A subunit. The alpha1A subunit is the main pore-forming subunit of the P/Q-type calcium channel. Patients with SCA6 suffer from a severe form of progressive ataxia and cerebellar dysfunction. Design of treatments for this disorder will depend on better definition of the mechanism of disease. As a disease arising from a mutation in an ion channel gene, SCA6 may behave as an ion channelopathy, and may respond to attempts to modulate or correct ion channel function. Alternatively, as a disease in which the mutant protein contains an expanded polyglutamine tract, SCA6 may respond to the targets of drug therapies developed for Huntington's disease and other polyglutamine disorders. In this review we will compare SCA6 to other polyglutamine diseases and channelopathies, and we will highlight recent advances in our understanding of alpha1A subunits and SCA6 pathology. We also propose a mechanism for how two seemingly divergent hypotheses can be combined into a cohesive model for disease progression.
Collapse
Affiliation(s)
- Holly B Kordasiewicz
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, California 92093, USA
| | | |
Collapse
|
37
|
Anelli R, Sanelli L, Bennett DJ, Heckman CJ. Expression of L-type calcium channel alpha(1)-1.2 and alpha(1)-1.3 subunits on rat sacral motoneurons following chronic spinal cord injury. Neuroscience 2007; 145:751-63. [PMID: 17291691 DOI: 10.1016/j.neuroscience.2006.12.043] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 12/10/2006] [Accepted: 12/11/2006] [Indexed: 12/22/2022]
Abstract
In the presence of the monoamines serotonin and norepinephrine, motoneurons readily generate large persistent inward currents (PICs). The resulting plateau potentials amplify and sustain motor output. Monoaminergic input to the cord originates in the brainstem and the sharp reduction in monoamine levels that occurs following acute spinal cord injury greatly decreases motoneuron excitability. However, recent studies in the adult sacral cord of the rat have shown that motoneurons reacquire the ability to generate PICs and plateau potentials within 1-2 months following spinal transection. Ca(v)1.3 L-type calcium channels are involved in generating PICs in both healthy and injured animals. Additionally, expression of Ca(v)1.2 and Ca(v)1.3 L-type calcium channels is altered in several pathological conditions. Therefore, in this paper we analyzed the expression of L-type calcium channel alpha(1) subunits within the motoneuron pool following a complete transection of the spinal cord at the level of the sacral vertebra (S)2 segment. The analysis was done both caudally (S4 segment) and rostrally [thoracic vertebra (T)6 segment] from the injury site. The S4 segment was significantly reduced in diameter when compared with control animals, and this reduction was more evident in the white matter. Ca(v)1.2 alpha(1) subunit expression significantly increased (26%) in the motoneuron pool located caudally but not rostrally from the injury site. In contrast, the expression of Ca(v)1.3 alpha(1) subunit remained unchanged in both S4 and T6 segments. The differential expression of the two alpha(1) subunits in spinal injury suggests that Ca(v)1.2 and Ca(v)1.3 channels have different functions in neuronal adaptation following spinal cord injury.
Collapse
Affiliation(s)
- R Anelli
- Department of Physiology, Northwestern University Feinberg School of Medicine, Morton 5-666, 303 East Chicago Avenue (M211), Chicago, IL 60611, USA.
| | | | | | | |
Collapse
|
38
|
Catterall WA, Cestèle S, Yarov-Yarovoy V, Yu FH, Konoki K, Scheuer T. Voltage-gated ion channels and gating modifier toxins. Toxicon 2007; 49:124-41. [PMID: 17239913 DOI: 10.1016/j.toxicon.2006.09.022] [Citation(s) in RCA: 458] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Voltage-gated sodium, calcium, and potassium channels generate electrical signals required for action potential generation and conduction and are the molecular targets for a broad range of potent neurotoxins. These channels are built on a common structural motif containing six transmembrane segments and a pore loop. Their pores are formed by the S5/S6 segments and the pore loop between them, and they are gated by bending of the S6 segments at a hinge glycine or proline residue. The voltage sensor domain consists of the S1-S4 segments, with positively charged residues in the S4 segment serving as gating charges. The diversity of toxin action on these channels is illustrated by sodium channels, which are the molecular targets for toxins that act at six or more distinct receptor sites on the channel protein. Both hydrophilic low molecular weight toxins and larger polypeptide toxins physically block the pore and prevent sodium conductance. Hydrophobic alkaloid toxins and related lipid-soluble toxins act at intramembrane sites and alter voltage-dependent gating of sodium channels via an allosteric mechanism. In contrast, polypeptide toxins alter channel gating by voltage-sensor trapping through binding to extracellular receptor sites, and this toxin interaction has now been modeled at the atomic level for a beta-scorpion toxin. The voltage-sensor trapping mechanism may be a common mode of action for polypeptide gating modifier toxins acting on all of the voltage-gated ion channels.
Collapse
Affiliation(s)
- William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA.
| | | | | | | | | | | |
Collapse
|
39
|
Shen H, Zhang B, Shin JH, Lei D, Du Y, Gao X, Wang Q, Ohlemiller KK, Piccirillo J, Bao J. Prophylactic and therapeutic functions of T-type calcium blockers against noise-induced hearing loss. Hear Res 2006; 226:52-60. [PMID: 17291698 PMCID: PMC1903349 DOI: 10.1016/j.heares.2006.12.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 12/21/2006] [Accepted: 12/23/2006] [Indexed: 11/16/2022]
Abstract
Cochlear noise injury is the second most frequent cause of sensorineural hearing loss, after aging. Because calcium dysregulation is a widely recognized contributor to noise injury, we examined the potential of calcium channel blockers to reduce noise-induced hearing loss (NIHL) in mice. We focused on two T-type calcium blockers, trimethadione and ethosuximide, which are anti-epileptics approved by the Food and Drug Administration. Young C57BL/6 mice of either gender were divided into three groups: a 'prevention' group receiving the blocker via drinking water before noise exposure; a 'treatment' group receiving the blocker via drinking water after noise exposure; and controls receiving noise alone. Trimethadione significantly reduced NIHL when applied before noise exposure, as determined by auditory brainstem recording. Both ethosuximide and trimethadione were effective in reducing NIHL when applied after noise exposure. Results were influenced by gender, with males generally receiving greater benefit than females. Quantitation of hair cell and neuronal density suggested that preservation of outer hair cells could account for the observed protection. Immunocytochemistry and RT-PCR suggested that this protection involves direct action of T-type blockers on alpha1 subunits comprising one or more Ca(v)3 calcium channel types in the cochlea. Our findings provide a basis for clinical studies testing T-type calcium blockers both to prevent and treat NIHL.
Collapse
Affiliation(s)
- Haiyan Shen
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
- Model Animal Research Center of Nanjing University, 12 Xue-Fu Road, Nanjing P.R. China, 210061
| | - Baoping Zhang
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - June-Ho Shin
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Debin Lei
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Yafei Du
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Xiang Gao
- Model Animal Research Center of Nanjing University, 12 Xue-Fu Road, Nanjing P.R. China, 210061
| | - Qiuju Wang
- Department of Otolaryngology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing, P.R. China, 100853
| | - Kevin K. Ohlemiller
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Jay Piccirillo
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Jianxin Bao
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
- **Corresponding Author: Jianxin Bao, Ph.D. Department of Otolaryngology, Washington University, 4560 Clayton Avenue, St. Louis, MO 63110, 314-747-7199, 314-747-7230 (fax),
| |
Collapse
|
40
|
HELL JOHANNESW, WESTENBROEK RUTHE, ELLIOTT ELICIAM, CATTERALL WILLIAMA. Differential Phosphorylation, Localization, and Function of Distinct α1 Subunits of Neuronal Calcium Channels. Ann N Y Acad Sci 2006. [DOI: 10.1111/j.1749-6632.1994.tb44416.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
41
|
Raybaud A, Dodier Y, Bissonnette P, Simoes M, Bichet DG, Sauvé R, Parent L. The Role of the GX9GX3G Motif in the Gating of High Voltage-activated Ca2+ Channels. J Biol Chem 2006; 281:39424-36. [PMID: 17038321 DOI: 10.1074/jbc.m607405200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The putative hinge point revealed by the crystal structure of the MthK potassium channel is a glycine residue that is conserved in many ion channels. In high voltage-activated (HVA) Ca(V) channels, the mid-S6 glycine residue is only present in IS6 and IIS6, corresponding to G422 and G770 in Ca(V)1.2. Two additional glycine residues are found in the distal portion of IS6 (Gly(432) and Gly(436) in Ca(V)1.2) to form a triglycine motif unique to HVA Ca(V) channels. Lethal arrhythmias are associated with mutations of glycine residues in the human L-type Ca(2+) channel. Hence, we undertook a mutational analysis to investigate the role of S6 glycine residues in channel gating. In Ca(V)1.2, alpha-helix-breaking proline mutants (G422P and G432P) as well as the double G422A/G432A channel did not produce functional channels. The macroscopic inactivation kinetics were significantly decreased with Ca(V)1.2 wild type > G770A > G422A congruent with G436A >> G432A (from the fastest to the slowest). Mutations at position Gly(432) produced mostly nonfunctional mutants. Macroscopic inactivation kinetics were markedly reduced by mutations of Gly(436) to Ala, Pro, Tyr, Glu, Arg, His, Lys, or Asp residues with stronger effects obtained with charged and polar residues. Mutations within the distal GX(3)G residues blunted Ca(2+)-dependent inactivation kinetics and prevented the increased voltage-dependent inactivation kinetics brought by positively charged residues in the I-II linker. In Ca(V)2.3, mutation of the distal glycine Gly(352) impacted significantly on the inactivation gating. Altogether, these data highlight the role of the GX(3)G motif in the voltage-dependent activation and inactivation gating of HVA Ca(V) channels with the distal glycine residue being mostly involved in the inactivation gating.
Collapse
Affiliation(s)
- Alexandra Raybaud
- Département de Physiologie and the Membrane Protein Research Group, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | | | | | | | | | | | | |
Collapse
|
42
|
Anderson AA, Altafaj X, Zheng Z, Wang ZM, Delbono O, Ronjat M, Treves S, Zorzato F. The junctional SR protein JP-45 affects the functional expression of the voltage-dependent Ca2+ channel Cav1.1. J Cell Sci 2006; 119:2145-55. [PMID: 16638807 PMCID: PMC2802288 DOI: 10.1242/jcs.02935] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
JP-45, an integral protein of the junctional face membrane of the skeletal muscle sarcoplasmic reticulum (SR), colocalizes with its Ca2+ -release channel (the ryanodine receptor), and interacts with calsequestrin and the skeletal-muscle dihydropyridine receptor Cav1. We have identified the domains of JP-45 and the Cav1.1 involved in this interaction, and investigated the functional effect of JP-45. The cytoplasmic domain of JP-45, comprising residues 1-80, interacts with Cav1.1. JP-45 interacts with two distinct and functionally relevant domains of Cav1.1, the I-II loop and the C-terminal region. Interaction between JP-45 and the I-II loop occurs through the alpha-interacting domain in the I-II loop. beta1a, a Cav1 subunit, also interacts with the cytosolic domain of JP-45, and its presence drastically reduces the interaction between JP-45 and the I-II loop. The functional effect of JP-45 on Cav1.1 activity was assessed by investigating charge movement in differentiated C2C12 myotubes after overexpression or depletion of JP-45. Overexpression of JP-45 decreased peak charge-movement and shifted VQ1/2 to a more negative potential (-10 mV). JP-45 depletion decreased both the content of Cav1.1 and peak charge-movements. Our data demonstrate that JP-45 is an important protein for functional expression of voltage-dependent Ca2+ channels.
Collapse
Affiliation(s)
- Ayuk A. Anderson
- Departments of Anaesthesia and Research
Basel University HospitalHebelstrasse 20, 4031 Basel,CH
| | - Xavier Altafaj
- Canaux calciques , fonctions et pathologies
INSERM : U607CEA : DSV/IRTSVUniversité Joseph Fourier - Grenoble I17, rue des martyrs 38054 Grenoble,FR
| | - Zhenlin Zheng
- Department of Physiology and Pharmacology, Gerontology
Wake Forest University School of MedicineWinston-Salem, NC 27157,US
| | - Zhong-Min Wang
- Department of Physiology and Pharmacology, Gerontology
Wake Forest University School of MedicineWinston-Salem, NC 27157,US
| | - Osvaldo Delbono
- Department of Physiology and Pharmacology, Gerontology
Wake Forest University School of MedicineWinston-Salem, NC 27157,US
- Department of Internal Medicine, Gerontology
Wake Forest University School of MedicineWinston-Salem, NC 27157,US
| | - Michel Ronjat
- Canaux calciques , fonctions et pathologies
INSERM : U607CEA : DSV/IRTSVUniversité Joseph Fourier - Grenoble I17, rue des martyrs 38054 Grenoble,FR
| | - Susan Treves
- Departments of Anaesthesia and Research
Basel University HospitalHebelstrasse 20, 4031 Basel,CH
| | - Francesco Zorzato
- Department of Experimental and Diagnostic Medicine
University of FerraraGeneral Pathology Section, Via Borsari 46, 44100 Ferrara,IT
- * Correspondence should be adressed to: Francesco Zorzato
| |
Collapse
|
43
|
Mann M, Haq W, Zabel T, Guenther E, Zrenner E, Ladewig T. Age-dependent changes in the regulation mechanisms for intracellular calcium ions in ganglion cells of the mouse retina. Eur J Neurosci 2006; 22:2735-43. [PMID: 16324107 DOI: 10.1111/j.1460-9568.2005.04475.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The purpose of this study was to investigate the role of intracellular calcium buffering in retinal ganglion cells. We performed a quantitative analysis of calcium homeostasis in ganglion cells of early postnatal and adult mice by simultaneous patch-clamp recordings in sliced tissue and microfluorometric calcium measurements with Fura-2. Endogenous calcium homeostasis was quantified by using the 'added buffer' approach which uses amplitudes and decay time constants of calcium transients to give a standard for intracellular calcium buffering. The recovery phase of depolarization-induced calcium transients was well approximated by a mono-exponential function with a decay time constant that showed a linear dependence on dye concentration. Endogenous calcium binding ratios were found to be 575 (n = 18 cells) in early postnatal and 121 (n = 18 cells) in adult retinal ganglion cells. With respect to ganglion cell degeneration at early postnatal stages, our measurements suggest that neuroprotection of a majority of developing ganglion cells partially results from a specialized calcium homeostasis based on high buffering capacities. Furthermore, the dramatic decrease of the intracellular calcium buffering capacity during ganglion cell development may enhance their vulnerability to neurodegeneration.
Collapse
Affiliation(s)
- Miriam Mann
- Department of Ophthalmology II, Augenklinik Abt. II, Forschungsstelle Experimentelle Ophthalmologie, Röntgenweg 11, 72076 Tübingen, Germany
| | | | | | | | | | | |
Collapse
|
44
|
Cook DG, Li X, Cherry SD, Cantrell AR. Presenilin 1 deficiency alters the activity of voltage-gated Ca2+ channels in cultured cortical neurons. J Neurophysiol 2005; 94:4421-9. [PMID: 16148264 DOI: 10.1152/jn.00745.2005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Presenilins 1 and 2 (PS1 and PS2, respectively) play a critical role in mediating gamma-secretase cleavage of the amyloid precursor protein (APP). Numerous mutations in the presenilins are known to cause early-onset familial Alzheimer's disease (FAD). In addition, it is well established that PS1 deficiency leads to altered intracellular Ca(2+) homeostasis involving endoplasmic reticulum Ca(2+) stores. However, there has been little evidence suggesting Ca(2+) signals from extracellular sources are influenced by PS1. Here we report that the Ca(2+) currents carried by voltage-dependent Ca(2+) channels are increased in PS1-deficient cortical neurons. This increase is mediated by a significant increase in the contributions of L- and P-type Ca(2+) channels to the total voltage-mediated Ca(2+) conductance in PS1 (-/-) neurons. In addition, chelating intracellular Ca(2+) with 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) produced an increase in Ca(2+) current amplitude that was comparable to the increase caused by PS1 deficiency. In contrast to this, BAPTA had no effect on voltage-dependent Ca(2+) conductances in PS1-deficient neurons. These data suggest that PS1 deficiency may influence voltage-gated Ca(2+) channel function by means that involve intracellular Ca(2+) signaling. These findings reveal that PS1 functions at multiple levels to regulate and stabilize intracellular Ca(2+) levels that ultimately control neuronal firing behavior and influence synaptic transmission.
Collapse
Affiliation(s)
- David G Cook
- Veterans Affairs Puget Sound Health Care System, Geriatric Research Education and Clinical Center (GRECC), Seattle, Washington, USA
| | | | | | | |
Collapse
|
45
|
Lorenzo SD, Veggetti M, Muchnik S, Losavio A. Presynaptic inhibition of spontaneous acetylcholine release induced by adenosine at the mouse neuromuscular junction. Br J Pharmacol 2004; 142:113-24. [PMID: 15066904 PMCID: PMC1574912 DOI: 10.1038/sj.bjp.0705656] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
1. At the mouse neuromuscular junction, adenosine (AD) and the A(1) agonist 2-chloro-N(6)-cyclopentyl-adenosine (CCPA) induce presynaptic inhibition of spontaneous acetylcholine (ACh) release by activation of A(1) AD receptors through a mechanism that is still unknown. To evaluate whether the inhibition is mediated by modulation of the voltage-dependent calcium channels (VDCCs) associated with tonic secretion (L- and N-type VDCCs), we measured the miniature end-plate potential (mepp) frequency in mouse diaphragm muscles. 2. Blockade of VDCCs by Cd(2+) prevented the effect of the CCPA. Nitrendipine (an L-type VDCC antagonist) but not omega-conotoxin GVIA (an N-type VDCC antagonist) blocked the action of CCPA, suggesting that the decrease in spontaneous mepp frequency by CCPA is associated with an action on L-type VDCCs only. 3. As A(1) receptors are coupled to a G(i/o) protein, we investigated whether the inhibition of PKA or the activation of PKC is involved in the presynaptic inhibition mechanism. Neither N-(2[p-bromocinnamylamino]-ethyl)-5-isoquinolinesulfonamide (H-89, a PKA inhibitor), nor 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine (H-7, a PKC antagonist), nor phorbol 12-myristate 13-acetate (PHA, a PKC activator) modified CCPA-induced presynaptic inhibition, suggesting that these second messenger pathways are not involved. 4. The effect of CCPA was eliminated by the calmodulin antagonist N-(6-aminohexil)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) and by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid-acetoxymethyl ester epsilon6TDelta-BM, which suggests that the action of CCPA to modulate L-type VDCCs may involve Ca(2+)-calmodulin. 5. To investigate the action of CCPA on diverse degrees of nerve terminal depolarization, we studied its effect at different external K(+) concentrations. The effect of CCPA on ACh secretion evoked by 10 mm K(+) was prevented by the P/Q-type VDCC antagonist omega-agatoxin IVA. 6. CCPA failed to inhibit the increases in mepp frequency evoked by 15 and 20 mm K(+). We demonstrated that, at high K(+) concentrations, endogenous AD occupies A1 receptors, impairing the action of CCPA, since incubation with 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, an A(1) receptor antagonist) and adenosine deaminase (ADA), which degrades AD into the inactive metabolite inosine, increased mepp frequency compared with that obtained in 15 and 20 mm K(+) in the absence of the drugs. Moreover, CCPA was able to induce presynaptic inhibition in the presence of ADA. It is concluded that, at high K(+) concentrations, the activation of A(1) receptors by endogenous AD prevents excessive neurotransmitter release.
Collapse
Affiliation(s)
- Silvana De Lorenzo
- Instituto de Investigaciones Médicas Alfredo Lanari, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1427, Argentina
| | - Mariela Veggetti
- Instituto de Investigaciones Médicas Alfredo Lanari, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1427, Argentina
| | - Salomón Muchnik
- Instituto de Investigaciones Médicas Alfredo Lanari, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1427, Argentina
| | - Adriana Losavio
- Instituto de Investigaciones Médicas Alfredo Lanari, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1427, Argentina
- Author for correspondence:
| |
Collapse
|
46
|
Westenbroek RE, Anderson NL, Byers MR. Altered localization of Cav1.2 (L-type) calcium channels in nerve fibers, Schwann cells, odontoblasts, and fibroblasts of tooth pulp after tooth injury. J Neurosci Res 2004; 75:371-83. [PMID: 14743450 DOI: 10.1002/jnr.10863] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We have determined the localization of Cav1.2 (L-Type) Ca2+ channels in the cells and nerve fibers in molars of normal or injured rats. We observed high levels of immunostaining of L-type Ca2+ channels in odontoblast cell bodies and their processes, in fibroblast cell bodies and in Schwann cells. Many Cav1.2-containing unmyelinated and myelinated axons were also present in root nerves and proximal branches in coronal pulp, but were usually missing from nerve fibers in dentin. Labeling in the larger fibers was present along the axonal membrane, localized in axonal vesicles, and in nodal regions. After focal tooth injury, there is a marked loss of Cav1.2 channels in injured teeth. Immunostaining of Cav1.2 channels was lost selectively in nerve fibers and local cells of the tooth pulp within 10 min of the lesion, without loss of other Cav channel or pulpal labels. By 60 min, Cav1.2 channels in odontoblasts were detected again but at levels below controls, whereas fibroblasts were labeled well above control levels, similar to upregulation of Cav1.2 channels in astrocytes after injury. By 3 days after the injury, Cav1.2 channels were again detected in nerve fibers and immunostaining of fibroblasts and odontoblasts had returned to control levels. These findings provide new insight into the localization of Cav1.2 channels in dental pulp and sensory fibers, and demonstrate unexpected plasticity of channel distribution in response to nerve injury.
Collapse
Affiliation(s)
- R E Westenbroek
- Department of Pharmacology, University of Washington, Seattle, USA.
| | | | | |
Collapse
|
47
|
Lee CW, Lee EH, Takeuchi K, Takahashi H, Shimada I, Sato K, Shin SY, Kim DH, Kim JI. Molecular basis of the high-affinity activation of type 1 ryanodine receptors by imperatoxin A. Biochem J 2004; 377:385-94. [PMID: 14535845 PMCID: PMC1223873 DOI: 10.1042/bj20031192] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2003] [Revised: 09/29/2003] [Accepted: 10/09/2003] [Indexed: 11/17/2022]
Abstract
Both imperatoxin A (IpTx(a)), a 33-residue peptide toxin from scorpion venom, and peptide A, derived from the II-III loop of dihydropyridine receptor (DHPR), interact specifically with the skeletal ryanodine receptor (RyR1), which is a Ca(2+)-release channel in the sarcoplasmic reticulum, but with considerably different affinities. IpTx(a) activates RyR1 with nanomolar affinity, whereas peptide A activates RyR1 at micromolar concentrations. To investigate the molecular basis for high-affinity activation of RyR1 by IpTx(a), we have determined the NMR solution structure of IpTx(a), and identified its functional surface by using alanine-scanning analogues. A detailed comparison of the functional surface profiles for two peptide activators revealed that IpTx(a) exhibits a large functional surface area (approx. 1900 A(2), where 1 A=0.1 nm), based on a short double-stranded antiparallel beta-sheet structure, while peptide A bears a much smaller functional surface area (approx. 800 A(2)), with the five consecutive basic residues (Arg(681), Lys(682), Arg(683), Arg(684) and Lys(685)) being clustered at the C-terminal end of the alpha-helix. The functional surface of IpTx(a) is composed of six essential residues (Leu(7), Lys(22), Arg(23), Arg(24), Arg(31) and Arg(33)) and several other important residues (His(6), Lys(8), Arg(9), Lys(11), Lys(19), Lys(20), Gly(25), Thr(26), Asn(27) and Lys(30)), indicating that amino acid residues involved in RyR1 activation make up over the half of the toxin molecule with the exception of cysteine residues. Taken together, these results suggest that the site where peptide A binds to RyR1 belongs to a subset of macrosites capable of being occupied by IpTx(a), resulting in differing the affinity and the mode of activation.
Collapse
Affiliation(s)
- Chul Won Lee
- Department of Life Science, Kwangju Institute of Science and Technology, Kwangju 500-712, South Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Cavelier P, Bossu JL. Dendritic low-threshold Ca2+ channels in rat cerebellar Purkinje cells: possible physiological implications. THE CEREBELLUM 2003; 2:196-205. [PMID: 14509569 DOI: 10.1080/14734220310016141] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Low-voltage activated (LVA) Ca2+ currents have been characterized in a large variety of neurons including cerebellar Purkinje cells (PCs). This review summarizes and discusses the biophysical, pharmacological properties, as well as the molecular identity of LVA Ca2+ channels described in PCs in various experimental conditions. Putative functional roles for LVA Ca2+ currents include generation of low-threshold Ca2+ spikes (LTS) that underlie burst firing, promotion of intrinsic oscillatory behaviour, Ca2+ entry close to the resting membrane potential and synaptic potentiation. Based on our recent findings on cerebellar rat PCs in slice cultures, this review presents the major evidence demonstrating that LVA Ca2+ channels produce a dendritic initiated LTS with a regulated propagation to the soma. This new role for LVA Ca2+ channels is particularly important in determining firing patterns in PCs.
Collapse
Affiliation(s)
- Pauline Cavelier
- Laboratoire de Neurotransmission et Sécrétion Neuroendocrine, Centre de Neurochimie, Strasbourg, France
| | | |
Collapse
|
49
|
Tamse CT, Xu Y, Song H, Nie L, Yamoah EN. Protein kinase A mediates voltage-dependent facilitation of Ca2+ current in presynaptic hair cells in Hermissenda crassicornis. J Neurophysiol 2003; 89:1718-26. [PMID: 12626635 DOI: 10.1152/jn.00766.2002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The simplest cellular model for classical conditioning in the nudibranch mollusk, Hermissenda crassicornis, involves the presynaptic hair cells and postsynaptic photoreceptors. Whereas the cellular mechanisms for postsynaptic photoreceptors have been studied extensively, the presynaptic mechanisms remain uncertain. Here, we determined the phenotype of the voltage-dependent Ca(2+) current in the presynaptic hair cells that may be directly involved in changes in synaptic efficacy during classical conditioning. The Ca(2+) current can be classified as a P-type current because its activation voltage under seawater recording conditions is approximately -30 mV, it showed slow inactivation, and it is reversibly blocked by omega-agatoxin-IVA. The steady-state activation and inactivation curves revealed a window current, and the single-channel conductance is approximately 20 pS. The P-type current was enhanced by cAMP analogs (approximately 1.3-fold), and by forskolin, an activator of adenylyl cyclase (approximately 1.25-fold). In addition, the P-type current showed voltage-dependent facilitation, which is mediated by protein kinase A (PKA). Specifically, the PKA inhibitor peptide [PKI(6-22)amide] blocked the enhancement of the Ca(2+) current produced by conditioning depolarization prepulses. Because neurotransmitter release is mediated by Ca(2+) influx via voltage-gated Ca(2+) channels, and because of the nonlinear relationship between the Ca(2+) influx and neurotransmitter release, we propose that voltage-dependent facilitation of the P-type current in hair cells would produce a robust change in synaptic efficacy.
Collapse
Affiliation(s)
- Catherine T Tamse
- Center for Neuroscience, Department of Otolaryngology, University of California, Davis, California 95616, USA
| | | | | | | | | |
Collapse
|
50
|
Endoh T, Kamaishi H, Suzuki T. Constitution of calcium channel current in hamster submandibular ganglion neurons. THE BULLETIN OF TOKYO DENTAL COLLEGE 2002; 43:251-6. [PMID: 12687731 DOI: 10.2209/tdcpublication.43.251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The submandibular ganglion (SMG) neuron has been well established as the parasympathetic ganglion that innervates the submandibular and sublingual salivary glands. Thus this neuron plays a key role in salivary secretion. In a previous study, we reported that SMG possessed T-, L-, N-, P/Q- and R-type voltage-dependent calcium channels (VDCCs). In this study, we analyzed the contribution of the distinct subtypes of VDCCs currents (ICa) using the whole-cell configuration of the patch clamp technique in SMG neurons. In addition, we also investigated the effects of a strong voltage prepulse on the contributions of the subtypes of VDCCs. In SMG neuronal ICa without a prepulse, the mean percentages of L-, N-, P-, Q- and R-type were 39.7, 31.5, 10.6, 7.1 and 7.9%. In SMG neuronal ICa with prepulse, the mean percentages of L-, N-, P-, Q- and R-type were 37.2, 34.0, 14.0, 7.6 and 7.0%. Thus, these results showed that SMG possess multiple types of VDCCs and that N- and P-type VDCCs are facilitated by a prepulse in SMG neurons.
Collapse
Affiliation(s)
- Takayuki Endoh
- Department of Physiology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan
| | | | | |
Collapse
|