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Younger DS. Neurogenetic motor disorders. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:183-250. [PMID: 37562870 DOI: 10.1016/b978-0-323-98818-6.00003-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Advances in the field of neurogenetics have practical applications in rapid diagnosis on blood and body fluids to extract DNA, obviating the need for invasive investigations. The ability to obtain a presymptomatic diagnosis through genetic screening and biomarkers can be a guide to life-saving disease-modifying therapy or enzyme replacement therapy to compensate for the deficient disease-causing enzyme. The benefits of a comprehensive neurogenetic evaluation extend to family members in whom identification of the causal gene defect ensures carrier detection and at-risk counseling for future generations. This chapter explores the many facets of the neurogenetic evaluation in adult and pediatric motor disorders as a primer for later chapters in this volume and a roadmap for the future applications of genetics in neurology.
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Affiliation(s)
- David S Younger
- Department of Clinical Medicine and Neuroscience, CUNY School of Medicine, New York, NY, United States; Department of Medicine, Section of Internal Medicine and Neurology, White Plains Hospital, White Plains, NY, United States.
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2
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Webster-Wood VA, Akkus O, Gurkan UA, Chiel HJ, Quinn RD. Organismal Engineering: Towards a Robotic Taxonomic Key for Devices Using Organic Materials. Sci Robot 2021; 2. [PMID: 31360812 DOI: 10.1126/scirobotics.aap9281] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Can we create robots with the behavioral flexibility and robustness of animals? Engineers often use bio-inspiration to mimic animals. Recent advances in tissue engineering now allow the use of components from animals. By integrating organic and synthetic components, researchers are moving towards the development of engineered organisms whose structural framework, actuation, sensing, and control are partially or completely organic. This review discusses recent exciting work demonstrating how organic components can be used for all facets of robot development. Based on this analysis, we propose a Robotic Taxonomic Key to guide the field towards a unified lexicon for device description.
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Affiliation(s)
| | - Ozan Akkus
- Dept. of Mech. and Aero. Engineering, Case Western Reserve University, Cleveland, OH, USA.,Dept. of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.,Dept. of Orthopaedics, Case Western Reserve University, Cleveland, OH, USA
| | - Umut A Gurkan
- Dept. of Mech. and Aero. Engineering, Case Western Reserve University, Cleveland, OH, USA.,Dept. of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.,Dept. of Orthopaedics, Case Western Reserve University, Cleveland, OH, USA
| | - Hillel J Chiel
- Dept. of Biology, Case Western Reserve University, Cleveland, OH, USA.,Dept. of Neurosciences, Case Western Reserve University, Cleveland, OH, USA.,Dept. of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Roger D Quinn
- Dept. of Mech. and Aero. Engineering, Case Western Reserve University, Cleveland, OH, USA
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3
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Bidaud I, Lory P. Hallmarks of the channelopathies associated with L-type calcium channels: a focus on the Timothy mutations in Ca(v)1.2 channels. Biochimie 2011; 93:2080-6. [PMID: 21664226 DOI: 10.1016/j.biochi.2011.05.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 05/19/2011] [Indexed: 11/29/2022]
Abstract
Within the voltage-gated calcium channels (Cav channels) family, there are four genes coding for the L-type Cav channels (Cav1). The Cav1 channels underly many important physiological functions like excitation-contraction coupling, hormone secretion, neuronal excitability and gene transcription. Mutations found in the genes encoding the Cav channels define a wide variety of diseases called calcium channelopathies and all four genes coding the Cav1 channels are carrying such mutations. L-type calcium channelopathies include muscular, neurological, cardiac and vision syndromes. Among them, the Timothy syndrome (TS) is linked to missense mutations in CACNA1C, the gene that encodes the Ca(v)1.2 subunit. Here we review the important features of the Cav1 channelopathies. We also report on the specific properties of TS-Ca(v)1.2 channels, which display non-inactivating calcium current as well as higher plasma membrane expression. Overall, we conclude that both electrophysiological and surface expression properties must be investigated to better account for the functional consequences of mutations linked to calcium channelopathies.
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Affiliation(s)
- Isabelle Bidaud
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France
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4
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Yang SN, Berggren PO. The role of voltage-gated calcium channels in pancreatic beta-cell physiology and pathophysiology. Endocr Rev 2006; 27:621-76. [PMID: 16868246 DOI: 10.1210/er.2005-0888] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Voltage-gated calcium (CaV) channels are ubiquitously expressed in various cell types throughout the body. In principle, the molecular identity, biophysical profile, and pharmacological property of CaV channels are independent of the cell type where they reside, whereas these channels execute unique functions in different cell types, such as muscle contraction, neurotransmitter release, and hormone secretion. At least six CaValpha1 subunits, including CaV1.2, CaV1.3, CaV2.1, CaV2.2, CaV2.3, and CaV3.1, have been identified in pancreatic beta-cells. These pore-forming subunits complex with certain auxiliary subunits to conduct L-, P/Q-, N-, R-, and T-type CaV currents, respectively. beta-Cell CaV channels take center stage in insulin secretion and play an important role in beta-cell physiology and pathophysiology. CaV3 channels become expressed in diabetes-prone mouse beta-cells. Point mutation in the human CaV1.2 gene results in excessive insulin secretion. Trinucleotide expansion in the human CaV1.3 and CaV2.1 gene is revealed in a subgroup of patients with type 2 diabetes. beta-Cell CaV channels are regulated by a wide range of mechanisms, either shared by other cell types or specific to beta-cells, to always guarantee a satisfactory concentration of Ca2+. Inappropriate regulation of beta-cell CaV channels causes beta-cell dysfunction and even death manifested in both type 1 and type 2 diabetes. This review summarizes current knowledge of CaV channels in beta-cell physiology and pathophysiology.
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Affiliation(s)
- Shao-Nian Yang
- The Rolf Luft Research Center for Diabetes and Endocrinology L1:03, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden.
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5
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Bidaud I, Mezghrani A, Swayne LA, Monteil A, Lory P. Voltage-gated calcium channels in genetic diseases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1169-74. [PMID: 17034879 DOI: 10.1016/j.bbamcr.2006.08.049] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Accepted: 08/30/2006] [Indexed: 11/16/2022]
Abstract
Voltage-gated calcium channels (VGCCs) mediate calcium entry into excitable cells in response to membrane depolarization. During the past decade, our understanding of the gating and functions of VGCCs has been illuminated by the analysis of mutations linked to a heterogeneous group of genetic diseases called "calcium channelopathies". Calcium channelopathies include muscular, neurological, cardiac and vision syndromes. Recent data suggest that calcium channelopathies result not only from electrophysiological defects but also from altered alpha(1)/Ca(V) subunit protein processing, including folding, posttranslational modifications, quality control and trafficking abnormalities. Overall, functional analyses of VGCC mutations provide a more comprehensive view of the corresponding human disorders and offer important new insights into VGCC function. Ultimately, the understanding of these pathogenic channel mutations should lead to improved treatments of such hereditary diseases in humans.
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Affiliation(s)
- Isabelle Bidaud
- Département de Physiologie, Institut de Génomique Fonctionnelle (IGF), CNRS UMR 5203--INSERM U661, Universités de Montpellier I and II, 141 rue de la Cardonille, 34094 Montpellier cedex 05, France
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6
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Lory P, Nargeot J. [Genetic diversity of voltage-gated calcium channels]. Rev Neurol (Paris) 2004; 160:S7-15. [PMID: 15269655 DOI: 10.1016/s0035-3787(04)71000-0] [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: 11/23/2022]
Abstract
Understanding of the properties of normal and diseased voltage-dependent calcium channels has greatly improved these last Years after the extensive development of the patch-clamp and molecular biology studies and the functional expression strategies. The calcium channel diversity is based on the expression of numerous genes that encode pore channel subunits (10 genes) and auxiliary/regulatory subunits (16 genes). In addition, most of these genes are subject to alternative splicing. The study of calcium channels has also benefited from the discovery of genetic diseases linked to calcium channel mutations: the calcium channelopathies. The review describes the recent data and working hypothesis that address the challenging question of how the calcium channel diversity occurs and how alterations in channel function lead to selective cellular dysfunction.
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Affiliation(s)
- P Lory
- Equipe Physiopathologie des Canaux Ioniques, Laboratoire de génomique fonctionnelle - CNRS UPR 2580, institut de génétique humaine, 141, rue de la Cardonille, 34094 Montpellier cedex 05, France
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7
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Abstract
T-type Ca2+ channels were originally called low-voltage-activated (LVA) channels because they can be activated by small depolarizations of the plasma membrane. In many neurons Ca2+ influx through LVA channels triggers low-threshold spikes, which in turn triggers a burst of action potentials mediated by Na+ channels. Burst firing is thought to play an important role in the synchronized activity of the thalamus observed in absence epilepsy, but may also underlie a wider range of thalamocortical dysrhythmias. In addition to a pacemaker role, Ca2+ entry via T-type channels can directly regulate intracellular Ca2+ concentrations, which is an important second messenger for a variety of cellular processes. Molecular cloning revealed the existence of three T-type channel genes. The deduced amino acid sequence shows a similar four-repeat structure to that found in high-voltage-activated (HVA) Ca2+ channels, and Na+ channels, indicating that they are evolutionarily related. Hence, the alpha1-subunits of T-type channels are now designated Cav3. Although mRNAs for all three Cav3 subtypes are expressed in brain, they vary in terms of their peripheral expression, with Cav3.2 showing the widest expression. The electrophysiological activities of recombinant Cav3 channels are very similar to native T-type currents and can be differentiated from HVA channels by their activation at lower voltages, faster inactivation, slower deactivation, and smaller conductance of Ba2+. The Cav3 subtypes can be differentiated by their kinetics and sensitivity to block by Ni2+. The goal of this review is to provide a comprehensive description of T-type currents, their distribution, regulation, pharmacology, and cloning.
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Affiliation(s)
- Edward Perez-Reyes
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908-0735, USA.
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8
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Stewart SL, Hogan K, Rosenberg H, Fletcher JE. Identification of the Arg1086His mutation in the alpha subunit of the voltage-dependent calcium channel (CACNA1S) in a North American family with malignant hyperthermia. Clin Genet 2001; 59:178-84. [PMID: 11260227 DOI: 10.1034/j.1399-0004.2001.590306.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Individuals from a large North American population were screened for the presence of the mutation in the alpha1 subunit of the voltage-dependent calcium channel (CACNA1S) that has recently been associated with malignant hyperthermia (MH). This Arg1086His mutation was screened for in 154 MH normal (MHN) individuals and 112 MH susceptible (MHS) individuals, who were diagnosed by the North American protocol of the in vitro contracture test. PCR and restriction enzyme analysis was used to test for the mutation. The Arg1086His mutation in the CACNA1S was not found in any of the MHN individuals. In contrast, two related individuals (grandfather and grandson, father and son of the MH proband) among the MHS group exhibited this mutation. However, a third MHS individual in the same family (granddaughter, cousin of the grandson) did not exhibit this mutation. These results indicate that this mutation may be associated with MH in this family. Genetic alterations in the CACNA1S associated with MH are present in approximately 1% of this North American MHS population.
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Affiliation(s)
- S L Stewart
- Department of Oncology, Georgetown University, Washington, DC 20007, USA.
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9
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Wielowieyski PA, Wigle JT, Salih M, Hum P, Tuana BS. Alternative splicing in intracellular loop connecting domains II and III of the alpha 1 subunit of Cav1.2 Ca2+ channels predicts two-domain polypeptides with unique C-terminal tails. J Biol Chem 2001; 276:1398-406. [PMID: 11010971 DOI: 10.1074/jbc.m006868200] [Citation(s) in RCA: 27] [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
Novel splice variants of the alpha(1) subunit of the Ca(v)1.2 voltage-gated Ca(2+) channel were identified that predicted two truncated forms of the alpha(1) subunit comprising domains I and II generated by alternative splicing in the intracellular loop region linking domains II and III. In rabbit heart splice variant 1 (RH-1), exon 19 was deleted, which resulted in a reading frameshift of exon 20 with a premature termination codon and a novel 19-amino acid carboxyl-terminal tail. In the RH-2 variant, exons 17 and 18 were deleted, leading to a reading frameshift of exons 19 and 20 with a premature stop codon and a novel 62-amino acid carboxyl-terminal tail. RNase protection assays with RH-1 and RH-2 cRNA probes confirmed the expression in cardiac and neuronal tissue but not skeletal muscle. The deduced amino acid sequence from full-length cDNAs encoding the two variants predicted polypeptides of 99.0 and 99.2 kDa, which constituted domains I and II of the alpha(1) subunit of the Ca(v)1.2 channel. Antipeptide antibodies directed to sequences in the second intracellular loop between domains II and III identified the 240-kDa Ca(v)1.2 subunit in sarcolemmal and heavy sarcoplasmic reticulum (HSR) membranes and a 99-kDa polypeptide in the HSR. An antipeptide antibody raised against unique sequences in the RH-2 variant also identified a 99-kDa polypeptide in the HSR. These data reveal the expression of additional Ca(2+) channel structural units generated by alternative splicing of the Ca(v)1.2 gene.
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Affiliation(s)
- P A Wielowieyski
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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10
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Abstract
Electrical signals are critical for the function of neurones, muscle cells, and cardiac myocytes. Proteins that regulate electrical signalling in these cells, including voltage gated ion channels, are logical sites where abnormality might lead to disease. Genetic and biophysical approaches are being used to show that several disorders result from mutations in voltage gated ion channels. Understanding gained from early studies on the pathogenesis of a group of muscle diseases that are similar in their episodic nature (periodic paralysis) showed that these disorders result from mutations in a gene encoding a voltage gated Na(+) channel. Their characterisation as channelopathies has served as a paradigm for other episodic disorders. For example, migraine headache and some forms of epilepsy have been shown to result from mutations in voltage gated Ca(2+) channel genes, while long QT syndrome is known to result from mutations in either K(+) or Na(+) channel genes. This article reviews progress made in the complementary fields of molecular genetics and cellular electrophysiology which has led to a better understanding of voltage gated ion channelopathies in humans and mice.
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Affiliation(s)
- R Felix
- Department of Physiology, Biophysics, and Neuroscience, Center for Research and Advanced Studies of the National Polytechnic Institute, Colonia Zacatenco, México DF, Mexico.
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11
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Gao B, Sekido Y, Maximov A, Saad M, Forgacs E, Latif F, Wei MH, Lerman M, Lee JH, Perez-Reyes E, Bezprozvanny I, Minna JD. Functional properties of a new voltage-dependent calcium channel alpha(2)delta auxiliary subunit gene (CACNA2D2). J Biol Chem 2000; 275:12237-42. [PMID: 10766861 PMCID: PMC3484885 DOI: 10.1074/jbc.275.16.12237] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have positionally cloned and characterized a new calcium channel auxiliary subunit, alpha(2)delta-2 (CACNA2D2), which shares 56% amino acid identity with the known alpha(2)delta-1 subunit. The gene maps to the critical human tumor suppressor gene region in chromosome 3p21.3, showing very frequent allele loss and occasional homozygous deletions in lung, breast, and other cancers. The tissue distribution of alpha(2)delta-2 expression is different from alpha(2)delta-1, and alpha(2)delta-2 mRNA is most abundantly expressed in lung and testis and well expressed in brain, heart, and pancreas. In contrast, alpha(2)delta-1 is expressed predominantly in brain, heart, and skeletal muscle. When co-expressed (via cRNA injections) with alpha(1B) and beta(3) subunits in Xenopus oocytes, alpha(2)delta-2 increased peak size of the N-type Ca(2+) currents 9-fold, and when co-expressed with alpha(1C) or alpha(1G) subunits in Xenopus oocytes increased peak size of L-type channels 2-fold and T-type channels 1.8-fold, respectively. Anti-peptide antibodies detect the expression of a 129-kDa alpha(2)delta-2 polypeptide in some but not all lung tumor cells. We conclude that the alpha(2)delta-2 gene encodes a functional auxiliary subunit of voltage-gated Ca(2+) channels. Because of its chromosomal location and expression patterns, CACNA2D2 needs to be explored as a potential tumor suppressor gene linking Ca(2+) signaling and lung, breast, and other cancer pathogenesis. The homologous location on mouse chromosome 9 is also the site of the mouse neurologic mutant ducky (du), and thus, CACNA2D2 is also a candidate gene for this inherited idiopathic generalized epilepsy syndrome.
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Affiliation(s)
- Boning Gao
- Hamon Center for Therapeutic Oncology Research, Department of Internal Medicine, Pharmacology, University of Texas, Southwestern Medical Center, Dallas, Texas 75390
| | - Yoshitaka Sekido
- Hamon Center for Therapeutic Oncology Research, Department of Internal Medicine, Pharmacology, University of Texas, Southwestern Medical Center, Dallas, Texas 75390
| | - Anton Maximov
- Department of Physiology, University of Texas, Southwestern Medical Center, Dallas, Texas 75390
| | - Mohamad Saad
- Hamon Center for Therapeutic Oncology Research, Department of Internal Medicine, Pharmacology, University of Texas, Southwestern Medical Center, Dallas, Texas 75390
| | - Eva Forgacs
- Hamon Center for Therapeutic Oncology Research, Department of Internal Medicine, Pharmacology, University of Texas, Southwestern Medical Center, Dallas, Texas 75390
| | - Farida Latif
- University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Ming H. Wei
- Laboratory of Immunobiology, NCI-Frederick Cancer Research and Development Center, Frederick, Maryland 21702
| | - Michael Lerman
- Laboratory of Immunobiology, NCI-Frederick Cancer Research and Development Center, Frederick, Maryland 21702
| | - Jung-Ha Lee
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Edward Perez-Reyes
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Ilya Bezprozvanny
- Department of Physiology, University of Texas, Southwestern Medical Center, Dallas, Texas 75390
| | - John D. Minna
- Hamon Center for Therapeutic Oncology Research, Department of Internal Medicine, Pharmacology, University of Texas, Southwestern Medical Center, Dallas, Texas 75390
- To whom correspondence should be addressed: Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-8593. Tel.: 214-648-4900; Fax: 214-648-4940;
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12
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Hogan K, Greg RG, Powers PA. Structure and alternative splicing of the gene encoding the human beta1 subunit of voltage dependent calcium channels. Neurosci Lett 1999; 277:111-4. [PMID: 10624822 DOI: 10.1016/s0304-3940(99)00851-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The structure of the gene encoding the human brain beta1 subunit of voltage dependent calcium channels (CACNB1) was determined by comparison of its genomic sequence with beta1 cDNA sequence. CACNB1 is distributed over 25 kb and contains 13 exons. Alternative splicing of CACNB1 RNA occurs within the central domain at exon 7, and the 3' domain at exon 13, producing the variably expressed beta1a, beta1b and beta1c isoforms. Exon/intron boundaries and exon lengths are conserved for the nine exons shared by the beta1 and related brain beta3 and beta4 genes.
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Affiliation(s)
- K Hogan
- Department of Anesthesiology, University of Wisconsin, Madison 53792, USA.
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13
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Schleithoff L, Mehrke G, Reutlinger B, Lehmann-Horn F. Genomic structure and functional expression of a human alpha(2)/delta calcium channel subunit gene (CACNA2). Genomics 1999; 61:201-9. [PMID: 10534405 DOI: 10.1006/geno.1999.5941] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
CACNA2 encodes the alpha(2)/delta subunit of the human voltage-gated calcium channels and is located in the candidate region of malignant hyperthermia susceptibility type 3 (MHS3). We determined the structural organization of CACNA2 by isolation of overlapping genomic DNA clones from a human phage library. The gene consists of at least 40 exons, 2 of which are alternatively spliced, spanning more than 150 kb of genomic DNA. Exons range from 21 to 159 bp, and introns range from 98 bp to at least more than 20 kb. We constructed a full-length cDNA and cloned it into a mammalian expression vector. Cotransfection of the CACNA2 cDNA with alpha(1A) and beta(4) cDNA into HEK293 cells led to the expression of Q-type calcium currents. The alpha(2)/delta subunit enhanced the current density 18-fold compared to cells transfected with only alpha(1A) and beta(4) cDNA. The sequence analysis provides the basis for comprehensive mutation screening of CACNA2 for putative MHS3 individuals and patients with other channelopathies.
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Affiliation(s)
- L Schleithoff
- Abteilung für Angewandte Physiologie, Universität Ulm, Ulm, Germany
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14
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Abstract
By the introduction of technological advancement in methods of structural analysis, electronics, and recombinant DNA techniques, research in physiology has become molecular. Additionally, focus of interest has been moving away from classical physiology to become increasingly centered on mechanisms of disease. A wonderful example for this development, as evident by this review, is the field of ion channel research which would not be nearly as advanced had it not been for human diseases to clarify. It is for this reason that structure-function relationships and ion channel electrophysiology cannot be separated from the genetic and clinical description of ion channelopathies. Unique among reviews of this topic is that all known human hereditary diseases of voltage-gated ion channels are described covering various fields of medicine such as neurology (nocturnal frontal lobe epilepsy, benign neonatal convulsions, episodic ataxia, hemiplegic migraine, deafness, stationary night blindness), nephrology (X-linked recessive nephrolithiasis, Bartter), myology (hypokalemic and hyperkalemic periodic paralysis, myotonia congenita, paramyotonia, malignant hyperthermia), cardiology (LQT syndrome), and interesting parallels in mechanisms of disease emphasized. Likewise, all types of voltage-gated ion channels for cations (sodium, calcium, and potassium channels) and anions (chloride channels) are described together with all knowledge about pharmacology, structure, expression, isoforms, and encoding genes.
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Affiliation(s)
- F Lehmann-Horn
- Department of Applied Physiology, University of Ulm, Ulm, Germany.
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15
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López I, Ishiyama G, Ishiyama A, Jen JC, Liu F, Baloh RW. Differential subcellular immunolocalization of voltage-gated calcium channel alpha1 subunits in the chinchilla cristae ampullaris. Neuroscience 1999; 92:773-82. [PMID: 10408625 DOI: 10.1016/s0306-4522(99)00005-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The immunohistochemical localization of alpha1A, alpha1B, alpha1C, alpha1D and alpha1E voltage-gated calcium channel subunits was investigated in the chinchilla cristae ampullaris and Scarpa's ganglia at the light and electron microscopy level with the use of specific antipeptide antibodies directed against these subunits. The stereocilia membrane of type I and type II hair cells was immunoreactive for alpha1B along its entire length. The basolateral membrane of both types of hair cells was alpha1B, alpha1C and alpha1D immunoreactive. Neurons in the Scarpa's ganglia and afferent nerve terminals in the cristae were immunoreactive for alpha1C and alpha1B. No specific immunoreactivity to alpha1A or alpha1E was seen in the sensory epithelia or ganglia. These findings are consistent with the presence of alpha1B (N-type channel), alpha1C and alpha1D (L-type channels) in the vestibular hair cells, and alpha1B (N-type channel) and alpha1C (L-type channel) in primary vestibular neurons.
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Affiliation(s)
- I López
- Department of Surgery (Head and Neck), UCLA School of Medicine, Los Angeles, California, USA
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16
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Yu DY, Su EN, Cringle SJ, Alder VA, Yu PK, DeSantis L. Systemic and ocular vascular roles of the antiglaucoma agents beta-adrenergic antagonists and Ca2+ entry blockers. Surv Ophthalmol 1999; 43 Suppl 1:S214-22. [PMID: 10416766 DOI: 10.1016/s0039-6257(99)00042-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This review addresses whether the antiglaucoma agents beta-adrenergic antagonists and Ca2+ entry blockers cause vasoactive effects in the retinal and other ocular vasculatures, as they do in other tissues. The potent vasodilating effects of Ca2+ entry blockers on ocular vessels have recently been demonstrated in in vivo and in vitro studies, implying that the maintenance of ocular vascular tone relies almost exclusively on extracellular Ca2+. Ca2+ entry blockers may potentially play a role in relaxing the retinal, long posterior ciliary, and ophthalmociliary arteries to improve the ocular circulation in vascular diseases in which there is considerable vascular tone present. The beta-adrenergic antagonists are discussed with reference to their antihypertensive role, their effect on other vascular beds, and finally what is known of their effect in the ocular vasculature. The emerging evidence that particular selective beta-adrenergic antagonists, such as betaxolol, are also potent Ca2+ channel entry blockers in other vascular beds is presented. Betaxolol has been shown to induce vasodilatation in the retinal and other ocular vascular beds, although studies have shown that beta1-adrenergic receptors are sparse in these vascular beds. This implies that an alternative mechanism must be responsible for betaxolol-induced vasodilatation. Evidence is presented that betaxolol vasodilates via its potent Ca2+ channel entry blocking properties, and its potency and ability to vasodilate are compared with those of nimodipine and timolol, as well as with those of other Ca2+ channel entry blockers. Important areas for future research in this area are discussed.
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Affiliation(s)
- D Y Yu
- Lions Eye Institute and Centre for Ophthalmology and Visual Science, University of Western Australia, Nedlands, Australia
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17
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Abstract
Fatal destruction of skeletal muscle coincident with exposure to specific drugs used during anethesia has been recognized as a potentially heritable disorder for more than 30 years. Variable expressivity and incomplete penetrance of the clinical malignant hyperthermia phenotype, together with inherent drawbacks of the in-vitro contracture test confounded efforts to discover the underlying pathogenesis until the application of molecular genetic techniques. On the basis of linkage analysis and mapping of positional candidate genes, mutant alleles at loci on chromosomes 1q, (dihydropyridine-sensitive L-type calcium channel-A1S); 3q, 5p, 7q (dihydropyridine-sensitive L-type calcium channel-LA2), and 19q (ryanodine receptor) are now believed to account for up to 50% of human malignant hyperthermia susceptibility. Although inconsistent genotype-phenotype correlations and doubts regarding the causality of each mutant allele persist, the definition of malignant hyperthermia and relevance of molecular genetic data to the problems of family counseling, population screening, and improved resolution of the malignant hyperthermia phenotype must now be appraised in view of significant locus and allelic genetic heterogeneity.
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Affiliation(s)
- K Hogan
- Department of Anesthesiology, University of Wisconsin, Madison 53792, USA.
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Ophoff RA, Terwindt GM, Frants RR, Ferrari MD. P/Q-type Ca2+ channel defects in migraine, ataxia and epilepsy. Trends Pharmacol Sci 1998; 19:121-7. [PMID: 9612085 DOI: 10.1016/s0165-6147(98)01182-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- R A Ophoff
- Neurogenetics Laboratory, University of California, San Francisco 94143-0984, USA
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Jodice C, Mantuano E, Veneziano L, Trettel F, Sabbadini G, Calandriello L, Francia A, Spadaro M, Pierelli F, Salvi F, Ophoff RA, Frants RR, Frontali M. Episodic ataxia type 2 (EA2) and spinocerebellar ataxia type 6 (SCA6) due to CAG repeat expansion in the CACNA1A gene on chromosome 19p. Hum Mol Genet 1997; 6:1973-8. [PMID: 9302278 DOI: 10.1093/hmg/6.11.1973] [Citation(s) in RCA: 200] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Point mutations of the CACNA1A gene coding for the alpha 1A voltage-dependent calcium channel subunit are responsible for familial hemiplegic migraine (FHM) and episodic ataxia type 2 (EA2). In addition, expansions of the CAG repeat motif at the 3' end of the gene, smaller than those responsible for dynamic mutation disorders, were found in patients with a progressive spinocerebellar ataxia, named SCA6. In the present work, the analysis of two new families with small CAG expansions of the CACNA1A gene is presented. In one family, with a clinical diagnosis of EA2, a CAG23 repeat allele segregated in patients showing different interictal symptoms, ranging from nystagmus only to severe progressive cerebellar ataxia. No additional mutations in coding and intron-exon junction sequences in disequilibrium with the CAG expansion were found. In the second family, initially classified as autosomal dominant cerebellar ataxia of unknown type, an inter-generational allele size change showed that a CAG20 allele was associated with an EA2 phenotype and a CAG25 allele with progressive cerebellar ataxia. These results show that EA2 and SCA6 are the same disorder with a high phenotypic variability, at least partly related to the number of repeats, and suggest that the small expansions may not be as stable as previously reported. A refinement of the coding and intron-exon junction sequences of the CACNA1A gene is also provided.
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Affiliation(s)
- C Jodice
- Dipartimento di Biologia, Università di Tor Vergata, Rome, Italy
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