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Scharinger A, Eckrich S, Vandael DH, Schönig K, Koschak A, Hecker D, Kaur G, Lee A, Sah A, Bartsch D, Benedetti B, Lieb A, Schick B, Singewald N, Sinnegger-Brauns MJ, Carbone E, Engel J, Striessnig J. Cell-type-specific tuning of Cav1.3 Ca(2+)-channels by a C-terminal automodulatory domain. Front Cell Neurosci 2015; 9:309. [PMID: 26379493 PMCID: PMC4547004 DOI: 10.3389/fncel.2015.00309] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 07/27/2015] [Indexed: 11/13/2022] Open
Abstract
Cav1.3 L-type Ca(2+)-channel function is regulated by a C-terminal automodulatory domain (CTM). It affects channel binding of calmodulin and thereby tunes channel activity by interfering with Ca(2+)- and voltage-dependent gating. Alternative splicing generates short C-terminal channel variants lacking the CTM resulting in enhanced Ca(2+)-dependent inactivation and stronger voltage-sensitivity upon heterologous expression. However, the role of this modulatory domain for channel function in its native environment is unkown. To determine its functional significance in vivo, we interrupted the CTM with a hemagglutinin tag in mutant mice (Cav1.3DCRD(HA/HA)). Using these mice we provide biochemical evidence for the existence of long (CTM-containing) and short (CTM-deficient) Cav1.3 α1-subunits in brain. The long (HA-labeled) Cav1.3 isoform was present in all ribbon synapses of cochlear inner hair cells. CTM-elimination impaired Ca(2+)-dependent inactivation of Ca(2+)-currents in hair cells but increased it in chromaffin cells, resulting in hyperpolarized resting potentials and reduced pacemaking. CTM disruption did not affect hearing thresholds. We show that the modulatory function of the CTM is affected by its native environment in different cells and thus occurs in a cell-type specific manner in vivo. It stabilizes gating properties of Cav1.3 channels required for normal electrical excitability.
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Affiliation(s)
- Anja Scharinger
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck Innsbruck, Austria
| | - Stephanie Eckrich
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, Saarland University Homburg, Germany
| | - David H Vandael
- Laboratory of Cellular and Molecular Neuroscience, Department of Drug Science, Nanostructured Interfaces and Surfaces Center, University of Torino Torino, Italy
| | - Kai Schönig
- Department of Molecular Biology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University Mannheim, Germany
| | - Alexandra Koschak
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck Innsbruck, Austria
| | - Dietmar Hecker
- Department of Otorhinolaryngology, Saarland University Homburg, Germany
| | - Gurjot Kaur
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck Innsbruck, Austria
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa Iowa City, IA, USA
| | - Anupam Sah
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck Innsbruck, Austria
| | - Dusan Bartsch
- Department of Molecular Biology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University Mannheim, Germany
| | - Bruno Benedetti
- Department of Physiology and Medical Physics, Innsbruck Medical University Innsbruck, Austria
| | - Andreas Lieb
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck Innsbruck, Austria
| | - Bernhard Schick
- Department of Otorhinolaryngology, Saarland University Homburg, Germany
| | - Nicolas Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck Innsbruck, Austria
| | - Martina J Sinnegger-Brauns
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck Innsbruck, Austria
| | - Emilio Carbone
- Laboratory of Cellular and Molecular Neuroscience, Department of Drug Science, Nanostructured Interfaces and Surfaces Center, University of Torino Torino, Italy
| | - Jutta Engel
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, Saarland University Homburg, Germany
| | - Jörg Striessnig
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck Innsbruck, Austria
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Burtscher V, Knoflach D, Kugler C, Scharinger A, Glösmann M, Blatsios G, Janecke A, Striessnig J, Obermair GJ, Schicker KW, Koschak A. Is There a Contribution of Both Cav1.4 and Cav1.3 L-Type Calcium Channels to Retinal Synaptic Transmission? Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Scharinger A, Hechenblaikner F, Bock G, Gebhart M, Schönig K, Bartsch D, Sah A, Singewald N, Sinnegger-Brauns MJ, Striessnig J. A mouse model to study the C-terminal regulation of CaV1.3 L-type calcium channels. BMC Pharmacol Toxicol 2012. [PMCID: PMC3506310 DOI: 10.1186/2050-6511-13-s1-a50] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
A C-terminal modulatory domain (CTM) tightly regulates the biophysical properties of Ca(v)1.3 L-type Ca(2+) channels, in particular the voltage dependence of activation (V(0.5)) and Ca(2+) dependent inactivation (CDI). A functional CTM is present in the long C-terminus of human and mouse Ca(v)1.3 (Ca(v)1.3(L)), but not in a rat long cDNA clone isolated from superior cervical ganglia neurons (rCa(v)1.3(scg)). We therefore addressed the question if this represents a species-difference and compared the biophysical properties of rCa(v)1.3(scg) with a rat cDNA isolated from rat pancreas (rCa(v)1.3(L)). When expressed in tsA-201 cells under identical experimental conditions rCa(v)1.3(L) exhibited Ca(2+) current properties indistinguishable from human and mouse Ca(v)1.3(L), compatible with the presence of a functional CTM. In contrast, rCa(v)1.3(scg) showed gating properties similar to human short splice variants lacking a CTM. rCa(v)1.3(scg) differs from rCa(v)1.3(L) at three single amino acid (aa) positions, one alternative spliced exon (exon31), and a N-terminal polymethionine stretch with two additional lysines. Two aa (S244, A2075) in rCa(v)1.3(scg) explained most of the functional differences to rCa(v)1.3(L). Their mutation to the corresponding residues in rCa(v)1.3(L) (G244, V2075) revealed that both contributed to the more negative V 0.5, but caused opposite effects on CDI. A2075 (located within a region forming the CTM) additionally permitted higher channel open probability. The cooperative action in the double-mutant restored gating properties similar to rCa(v)1.3(L). We found no evidence for transcripts containing one of the single rCa(v)1.3(scg) mutations in rat superior cervical ganglion preparations. However, the rCa(v)1.3(scg) variant provided interesting insight into the structural machinery involved in Ca(v)1.3 gating.
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Affiliation(s)
- Andreas Lieb
- Institute of Pharmacy and Center for Molecular Biosciences, University of Innsbruck, Austria
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Bock G, Gebhart M, Scharinger A, Jangsangthong W, Busquet P, Poggiani C, Sartori S, Mangoni ME, Sinnegger-Brauns MJ, Herzig S, Striessnig J, Koschak A. Functional properties of a newly identified C-terminal splice variant of Cav1.3 L-type Ca2+ channels. J Biol Chem 2011; 286:42736-42748. [PMID: 21998310 PMCID: PMC3234942 DOI: 10.1074/jbc.m111.269951] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
An intramolecular interaction between a distal (DCRD) and a proximal regulatory domain (PCRD) within the C terminus of long Ca(v)1.3 L-type Ca(2+) channels (Ca(v)1.3(L)) is a major determinant of their voltage- and Ca(2+)-dependent gating kinetics. Removal of these regulatory domains by alternative splicing generates Ca(v)1.3(42A) channels that activate at a more negative voltage range and exhibit more pronounced Ca(2+)-dependent inactivation. Here we describe the discovery of a novel short splice variant (Ca(v)1.3(43S)) that is expressed at high levels in the brain but not in the heart. It lacks the DCRD but, in contrast to Ca(v)1.3(42A), still contains PCRD. When expressed together with α2δ1 and β3 subunits in tsA-201 cells, Ca(v)1.3(43S) also activated at more negative voltages like Ca(v)1.3(42A) but Ca(2+)-dependent inactivation was less pronounced. Single channel recordings revealed much higher channel open probabilities for both short splice variants as compared with Ca(v)1.3(L). The presence of the proximal C terminus in Ca(v)1.3(43S) channels preserved their modulation by distal C terminus-containing Ca(v)1.3- and Ca(v)1.2-derived C-terminal peptides. Removal of the C-terminal modulation by alternative splicing also induced a faster decay of Ca(2+) influx during electrical activities mimicking trains of neuronal action potentials. Our findings extend the spectrum of functionally diverse Ca(v)1.3 L-type channels produced by tissue-specific alternative splicing. This diversity may help to fine tune Ca(2+) channel signaling and, in the case of short variants lacking a functional C-terminal modulation, prevent excessive Ca(2+) accumulation during burst firing in neurons. This may be especially important in neurons that are affected by Ca(2+)-induced neurodegenerative processes.
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Affiliation(s)
- Gabriella Bock
- Institute of Pharmacy, Pharmacology and Toxicology and Center of Molecular Biosciences Innsbruck, Peter-Mayr-Strasse 1/I, A-6020 Innsbruck, Austria
| | - Mathias Gebhart
- Institute of Pharmacy, Pharmacology and Toxicology and Center of Molecular Biosciences Innsbruck, Peter-Mayr-Strasse 1/I, A-6020 Innsbruck, Austria
| | - Anja Scharinger
- Institute of Pharmacy, Pharmacology and Toxicology and Center of Molecular Biosciences Innsbruck, Peter-Mayr-Strasse 1/I, A-6020 Innsbruck, Austria
| | - Wanchana Jangsangthong
- Department of Pharmacology and Center for Molecular Medicine, University of Cologne, Gleueler Strasse 24 and Robert-Koch-Strasse 21, D-50931 Cologne, Germany
| | - Perrine Busquet
- Institute of Pharmacy, Pharmacology and Toxicology and Center of Molecular Biosciences Innsbruck, Peter-Mayr-Strasse 1/I, A-6020 Innsbruck, Austria
| | - Chiara Poggiani
- Institute of Pharmacy, Pharmacology and Toxicology and Center of Molecular Biosciences Innsbruck, Peter-Mayr-Strasse 1/I, A-6020 Innsbruck, Austria
| | - Simone Sartori
- Institute of Pharmacy, Pharmacology and Toxicology and Center of Molecular Biosciences Innsbruck, Peter-Mayr-Strasse 1/I, A-6020 Innsbruck, Austria
| | - Matteo E Mangoni
- Département de Physiologie, CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34000 Montpellier, France; INSERM, U661, F-34000 Montpellier, France; Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France; INSERM, U637, Montpellier, France
| | - Martina J Sinnegger-Brauns
- Institute of Pharmacy, Pharmacology and Toxicology and Center of Molecular Biosciences Innsbruck, Peter-Mayr-Strasse 1/I, A-6020 Innsbruck, Austria
| | - Stefan Herzig
- Department of Pharmacology and Center for Molecular Medicine, University of Cologne, Gleueler Strasse 24 and Robert-Koch-Strasse 21, D-50931 Cologne, Germany
| | - Jörg Striessnig
- Institute of Pharmacy, Pharmacology and Toxicology and Center of Molecular Biosciences Innsbruck, Peter-Mayr-Strasse 1/I, A-6020 Innsbruck, Austria.
| | - Alexandra Koschak
- Institute of Pharmacy, Pharmacology and Toxicology and Center of Molecular Biosciences Innsbruck, Peter-Mayr-Strasse 1/I, A-6020 Innsbruck, Austria.
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Lieb A, Scharinger A, Hechenblaickner F, Gebhart M, Koschak A, Sinnegger-Brauns MJ, Striessnig J. Structural determinants of CaV1.3 L-type calcium channel gating. BMC Pharmacol 2011. [PMCID: PMC3194243 DOI: 10.1186/1471-2210-11-s2-a11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Juhasz-Vedres G, Scharinger A, Gebhart M, Busquet P, Poggiani C, Sartori SB, Sinnegger-Brauns MJ, Koschak A, Striessnig J. Identification of a new C-terminal splice variant of CaV1.3 L-type calcium channels with unique functional properties. BMC Pharmacol 2011. [PMCID: PMC3194279 DOI: 10.1186/1471-2210-11-s2-a44] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
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