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Hodges SL, Bouza AA, Isom LL. Therapeutic Potential of Targeting Regulated Intramembrane Proteolysis Mechanisms of Voltage-Gated Ion Channel Subunits and Cell Adhesion Molecules. Pharmacol Rev 2022; 74:1028-1048. [PMID: 36113879 PMCID: PMC9553118 DOI: 10.1124/pharmrev.121.000340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/13/2022] [Indexed: 10/03/2023] Open
Abstract
Several integral membrane proteins undergo regulated intramembrane proteolysis (RIP), a tightly controlled process through which cells transmit information across and between intracellular compartments. RIP generates biologically active peptides by a series of proteolytic cleavage events carried out by two primary groups of enzymes: sheddases and intramembrane-cleaving proteases (iCLiPs). Following RIP, fragments of both pore-forming and non-pore-forming ion channel subunits, as well as immunoglobulin super family (IgSF) members, have been shown to translocate to the nucleus to function in transcriptional regulation. As an example, the voltage-gated sodium channel β1 subunit, which is also an IgSF-cell adhesion molecule (CAM), is a substrate for RIP. β1 RIP results in generation of a soluble intracellular domain, which can regulate gene expression in the nucleus. In this review, we discuss the proposed RIP mechanisms of voltage-gated sodium, potassium, and calcium channel subunits as well as the roles of their generated proteolytic products in the nucleus. We also discuss other RIP substrates that are cleaved by similar sheddases and iCLiPs, such as IgSF macromolecules, including CAMs, whose proteolytically generated fragments function in the nucleus. Importantly, dysfunctional RIP mechanisms are linked to human disease. Thus, we will also review how understanding RIP events and subsequent signaling processes involving ion channel subunits and IgSF proteins may lead to the discovery of novel therapeutic targets. SIGNIFICANCE STATEMENT: Several ion channel subunits and immunoglobulin superfamily molecules have been identified as substrates of regulated intramembrane proteolysis (RIP). This signal transduction mechanism, which generates polypeptide fragments that translocate to the nucleus, is an important regulator of gene transcription. RIP may impact diseases of excitability, including epilepsy, cardiac arrhythmia, and sudden death syndromes. A thorough understanding of the role of RIP in gene regulation is critical as it may reveal novel therapeutic strategies for the treatment of previously intractable diseases.
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Affiliation(s)
- Samantha L Hodges
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
| | - Alexandra A Bouza
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
| | - Lori L Isom
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
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Vergnol A, Traoré M, Pietri-Rouxel F, Falcone S. New Insights in CaVβ Subunits: Role in the Regulation of Gene Expression and Cellular Homeostasis. Front Cell Dev Biol 2022; 10:880441. [PMID: 35465309 PMCID: PMC9019481 DOI: 10.3389/fcell.2022.880441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 03/16/2022] [Indexed: 11/23/2022] Open
Abstract
The voltage-gated calcium channels (CaVs or VGCCs) are fundamental regulators of intracellular calcium homeostasis. When electrical activity induces their activation, the influx of calcium that they mediate or their interaction with intracellular players leads to changes in intracellular Ca2+ levels which regulate many processes such as contraction, secretion and gene expression, depending on the cell type. The essential component of the pore channel is the CaVα1 subunit. However, the fine-tuning of Ca2+-dependent signals is guaranteed by the modulatory role of the auxiliary subunits β, α2δ, and γ of the CaVs. In particular, four different CaVβ proteins (CaVβ1, CaVβ2, CaVβ3, and CaVβ4) are encoded by four different genes in mammalians, each of them displaying several splice variants. Some of these isoforms have been described in regulating CaVα1 docking and stability at the membrane and controlling the channel complex’s conformational changes. In addition, emerging evidences have highlighted other properties of the CaVβ subunits, independently of α1 and non-correlated to its channel or voltage sensing functions. This review summarizes the recent findings reporting novel roles of the auxiliary CaVβ subunits and in particular their direct or indirect implication in regulating gene expression in different cellular contexts.
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Heck J, Palmeira Do Amaral AC, Weißbach S, El Khallouqi A, Bikbaev A, Heine M. More than a pore: How voltage-gated calcium channels act on different levels of neuronal communication regulation. Channels (Austin) 2021; 15:322-338. [PMID: 34107849 PMCID: PMC8205089 DOI: 10.1080/19336950.2021.1900024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 02/06/2023] Open
Abstract
Voltage-gated calcium channels (VGCCs) represent key regulators of the calcium influx through the plasma membrane of excitable cells, like neurons. Activated by the depolarization of the membrane, the opening of VGCCs induces very transient and local changes in the intracellular calcium concentration, known as calcium nanodomains, that in turn trigger calcium-dependent signaling cascades and the release of chemical neurotransmitters. Based on their central importance as concierges of excitation-secretion coupling and therefore neuronal communication, VGCCs have been studied in multiple aspects of neuronal function and malfunction. However, studies on molecular interaction partners and recent progress in omics technologies have extended the actual concept of these molecules. With this review, we want to illustrate some new perspectives of VGCCs reaching beyond their function as calcium-permeable pores in the plasma membrane. Therefore, we will discuss the relevance of VGCCs as voltage sensors in functional complexes with ryanodine receptors, channel-independent actions of auxiliary VGCC subunits, and provide an insight into how VGCCs even directly participate in gene regulation. Furthermore, we will illustrate how structural changes in the intracellular C-terminus of VGCCs generated by alternative splicing events might not only affect the biophysical channel characteristics but rather determine their molecular environment and downstream signaling pathways.
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Affiliation(s)
- Jennifer Heck
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Ana Carolina Palmeira Do Amaral
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Stephan Weißbach
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
- Computational Genomics and Bioinformatics, Johannes Gutenberg-University Mainz, University Medical Center Mainz, Institute for Human Genetics, Mainz, Germany
| | - Abderazzaq El Khallouqi
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Arthur Bikbaev
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Martin Heine
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
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Human Pluripotent Stem Cell-Derived Neurons Are Functionally Mature In Vitro and Integrate into the Mouse Striatum Following Transplantation. Mol Neurobiol 2020; 57:2766-2798. [PMID: 32356172 PMCID: PMC7253531 DOI: 10.1007/s12035-020-01907-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 03/23/2020] [Indexed: 01/23/2023]
Abstract
Human pluripotent stem cells (hPSCs) are a powerful tool for modelling human development. In recent years, hPSCs have become central in cell-based therapies for neurodegenerative diseases given their potential to replace affected neurons. However, directing hPSCs into specific neuronal types is complex and requires an accurate protocol that mimics endogenous neuronal development. Here we describe step-by-step a fast feeder-free neuronal differentiation protocol to direct hPSCs to mature forebrain neurons in 37 days in vitro (DIV). The protocol is based upon a combination of specific morphogens, trophic and growth factors, ions, neurotransmitters and extracellular matrix elements. A human-induced PSC line (Ctr-Q33) and a human embryonic stem cell line (GEN-Q18) were used to reinforce the potential of the protocol. Neuronal activity was analysed by single-cell calcium imaging. At 8 DIV, we obtained a homogeneous population of hPSC-derived neuroectodermal progenitors which self-arranged in bi-dimensional neural tube-like structures. At 16 DIV, we generated hPSC-derived neural progenitor cells (NPCs) with mostly a subpallial identity along with a subpopulation of pallial NPCs. Terminal in vitro neuronal differentiation was confirmed by the expression of microtubule associated protein 2b (Map 2b) by almost 100% of hPSC-derived neurons and the expression of specific-striatal neuronal markers including GABA, CTIP2 and DARPP-32. HPSC-derived neurons showed mature and functional phenotypes as they expressed synaptic markers, voltage-gated ion channels and neurotransmitter receptors. Neurons displayed diverse spontaneous activity patterns that were classified into three major groups, namely “high”, “intermediate” and “low” firing neurons. Finally, transplantation experiments showed that the NPCs survived and differentiated within mouse striatum for at least 3 months. NPCs integrated host environmental cues and differentiated into striatal medium-sized spiny neurons (MSNs), which successfully integrated into the endogenous circuitry without teratoma formation. Altogether, these findings demonstrate the potential of this robust human neuronal differentiation protocol, which will bring new opportunities for the study of human neurodevelopment and neurodegeneration, and will open new avenues in cell-based therapies, pharmacological studies and alternative in vitro toxicology.
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Andrade A, Brennecke A, Mallat S, Brown J, Gomez-Rivadeneira J, Czepiel N, Londrigan L. Genetic Associations between Voltage-Gated Calcium Channels and Psychiatric Disorders. Int J Mol Sci 2019; 20:E3537. [PMID: 31331039 PMCID: PMC6679227 DOI: 10.3390/ijms20143537] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/12/2019] [Accepted: 07/13/2019] [Indexed: 12/23/2022] Open
Abstract
Psychiatric disorders are mental, behavioral or emotional disorders. These conditions are prevalent, one in four adults suffer from any type of psychiatric disorders world-wide. It has always been observed that psychiatric disorders have a genetic component, however, new methods to sequence full genomes of large cohorts have identified with high precision genetic risk loci for these conditions. Psychiatric disorders include, but are not limited to, bipolar disorder, schizophrenia, autism spectrum disorder, anxiety disorders, major depressive disorder, and attention-deficit and hyperactivity disorder. Several risk loci for psychiatric disorders fall within genes that encode for voltage-gated calcium channels (CaVs). Calcium entering through CaVs is crucial for multiple neuronal processes. In this review, we will summarize recent findings that link CaVs and their auxiliary subunits to psychiatric disorders. First, we will provide a general overview of CaVs structure, classification, function, expression and pharmacology. Next, we will summarize tools to study risk loci associated with psychiatric disorders. We will examine functional studies of risk variations in CaV genes when available. Finally, we will review pharmacological evidence of the use of CaV modulators to treat psychiatric disorders. Our review will be of interest for those studying pathophysiological aspects of CaVs.
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Affiliation(s)
- Arturo Andrade
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA.
| | - Ashton Brennecke
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Shayna Mallat
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Julian Brown
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | | | - Natalie Czepiel
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Laura Londrigan
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
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González-Ramírez R, Felix R. Transcriptional regulation of voltage-gated Ca 2+ channels. Acta Physiol (Oxf) 2018; 222. [PMID: 28371478 DOI: 10.1111/apha.12883] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 02/14/2017] [Accepted: 03/21/2017] [Indexed: 12/30/2022]
Abstract
The transcriptional regulation of voltage-gated Ca2+ (CaV ) channels is an emerging research area that promises to improve our understanding of how many relevant physiological events are shaped in the central nervous system, the skeletal muscle and other tissues. Interestingly, a picture of how transcription of CaV channel subunit genes is controlled is evolving with the identification of the promoter regions required for tissue-specific expression and the identification of transcription factors that control their expression. These promoters share several characteristics that include multiple transcriptional start sites, lack of a TATA box and the presence of elements conferring tissue-selective expression. Likewise, changes in CaV channel expression occur throughout development, following ischaemia, seizures or chronic drug administration. This review focuses on insights achieved regarding the control of CaV channel gene expression. To further understand the complexities of expression and to increase the possibilities of detecting CaV channel alterations causing human disease, a deeper knowledge on the structure of the 5' upstream regions of the genes encoding these remarkable proteins will be necessary.
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Affiliation(s)
- R. González-Ramírez
- Departamento de Biología Molecular e Histocompatibilidad; Hospital General ‘Dr. Manuel Gea González’; Secretaría de Salud; Ciudad de México México
| | - R. Felix
- Departmento de Biología Celular; Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav-IPN); Ciudad de México México
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7
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Rima M, Daghsni M, Lopez A, Fajloun Z, Lefrancois L, Dunach M, Mori Y, Merle P, Brusés JL, De Waard M, Ronjat M. Down-regulation of the Wnt/β-catenin signaling pathway by Cacnb4. Mol Biol Cell 2017; 28:3699-3708. [PMID: 29021340 PMCID: PMC5706996 DOI: 10.1091/mbc.e17-01-0076] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 10/02/2017] [Accepted: 10/04/2017] [Indexed: 11/29/2022] Open
Abstract
The β4 isoform of the β-subunits of voltage-gated calcium channel regulates cell proliferation and cell cycle progression. Herein we show that coexpression of the β4-subunit with actors of the canonical Wnt/β-catenin signaling pathway in a hepatoma cell line inhibits Wnt-responsive gene transcription and decreases cell division, in agreement with the role of the Wnt pathway in cell proliferation. β4-subunit-mediated inhibition of Wnt signaling is observed in the presence of LiCl, an inhibitor of glycogen synthase kinase (GSK3) that promotes β-catenin translocation to the nucleus. Expression of β4-subunit mutants that lost the ability to translocate to the nucleus has no effect on Wnt signaling, suggesting that β4-subunit inhibition of Wnt signaling occurs downstream from GSK3 and requires targeting of β4-subunit to the nucleus. β4-subunit coimmunoprecipitates with the TCF4 transcription factor and overexpression of TCF4 reverses the effect of β4-subunit on the Wnt pathway. We thus propose that the interaction of nuclear β4-subunit with TCF4 prevents β-catenin binding to TCF4 and leads to the inhibition of the Wnt-responsive gene transcription. Thereby, our results show that β4-subunit is a TCF4 repressor and therefore appears as an interesting candidate for the regulation of this pathway in neurons where β4-subunit is specifically expressed.
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Affiliation(s)
- Mohamad Rima
- L'institut du thorax, INSER, CNRS, Université de Nantes, 44000 Nantes, France
- LabEx Ion Channels Science and Therapeutics, Valbone 06560, France
- Azm Center for Research in Biotechnology and Its Application, Lebanese University, 1300 Tripoli, Lebanon
| | - Marwa Daghsni
- L'institut du thorax, INSER, CNRS, Université de Nantes, 44000 Nantes, France
- Université de Tunis El Manar, Faculté de Médecine de Tunis, LR99ES10 Laboratoire de Génétique Humaine, 1007 Tunis, Tunisie
| | - Anaïs Lopez
- INSERM U1052, Team on Hepatocarcinogenesis and Viral Infections, Centre of Research in Cancerology of Lyon, Claude Bernard Lyon 1 University, 69100 Villeurbanne, France
- Hepatology Unit, Croix-Rousse Hospital, 69000 Lyon, France
| | - Ziad Fajloun
- Azm Center for Research in Biotechnology and Its Application, Lebanese University, 1300 Tripoli, Lebanon
| | - Lydie Lefrancois
- INSERM U1052, Team on Hepatocarcinogenesis and Viral Infections, Centre of Research in Cancerology of Lyon, Claude Bernard Lyon 1 University, 69100 Villeurbanne, France
- Hepatology Unit, Croix-Rousse Hospital, 69000 Lyon, France
| | - Mireia Dunach
- Departament de Bioquímica i Biologia Molecular, CEB, Facultat de Medicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry, Laboratory of Molecular Biology, Graduate School of Engineering, Kyoto University, 615-8510 Kyoto, Japan
| | - Philippe Merle
- INSERM U1052, Team on Hepatocarcinogenesis and Viral Infections, Centre of Research in Cancerology of Lyon, Claude Bernard Lyon 1 University, 69100 Villeurbanne, France
- Hepatology Unit, Croix-Rousse Hospital, 69000 Lyon, France
| | - Juan L Brusés
- Department of Natural Sciences, Mercy College, Dobbs Ferry, NY 10522
| | - Michel De Waard
- L'institut du thorax, INSER, CNRS, Université de Nantes, 44000 Nantes, France
- LabEx Ion Channels Science and Therapeutics, Valbone 06560, France
- Smartox Biotechnology, 38400 Saint-Martin d'Hères, France
| | - Michel Ronjat
- L'institut du thorax, INSER, CNRS, Université de Nantes, 44000 Nantes, France
- LabEx Ion Channels Science and Therapeutics, Valbone 06560, France
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8
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Rima M, Daghsni M, De Waard S, Gaborit N, Fajloun Z, Ronjat M, Mori Y, Brusés JL, De Waard M. The β 4 subunit of the voltage-gated calcium channel (Cacnb4) regulates the rate of cell proliferation in Chinese Hamster Ovary cells. Int J Biochem Cell Biol 2017; 89:57-70. [PMID: 28587927 DOI: 10.1016/j.biocel.2017.05.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/20/2017] [Accepted: 05/30/2017] [Indexed: 01/03/2023]
Abstract
The β subunits of Voltage-Gated Calcium Channel (VGCC) are cytosolic proteins that interact with the VGCC pore -forming subunit and participate in the trafficking of the channel to the cell membrane and in ion influx regulation. β subunits also exert functions independently of their binding to VGCC by translocation to the cell nucleus including the control of gene expression. Mutations of the neuronal Cacnb4 (β4) subunit are linked to human neuropsychiatric disorders including epilepsy and intellectual disabilities. It is believed that the pathogenic phenotype induced by these mutations is associated with channel-independent functions of the β4 subunit. In this report, we investigated the role of β4 subunit in cell proliferation and cell cycle progression and examined whether these functions could be altered by a pathogenic mutation. To this end, stably transfected Chinese Hamster Ovary (CHO-K1) cells expressing either rat full-length β4 or the rat C-terminally truncated epileptic mutant variant β1-481 were generated. The subcellular localization of both proteins differed significantly. Full-length β4 localizes almost exclusively in the cell nucleus and concentrates into the nucleolar compartment, while the C-terminal-truncated β1-481 subunit was less concentrated within the nucleus and absent from the nucleoli. Cell proliferation was found to be reduced by the expression of β4, while it was unaffected by the epileptic mutant. Also, full-length β4 interfered with cell cycle progression by presumably preventing cells from entering the S-phase via a mechanism that partially involves endogenous B56δ, a regulatory subunit of the phosphatase 2A (PP2A) that binds β4 but not β1-481. Analysis of β4 subcellular distribution during the cell cycle revealed that the protein is highly expressed in the nucleus at the G1/S transition phase and that it is translocated out of the nucleus during chromatin condensation and cell division. These results suggest that nuclear accumulation of β4 at the G1/S transition phase affects the progression into S-phase resulting in a decrease in the rate of cell proliferation. Regulation of the cell cycle exit is a critical step in determining the number of neuronal precursors and neuronal differentiation suggesting that mutations of the β4 subunit could affect neural development and formation of the mature central nervous system.
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Affiliation(s)
- Mohamad Rima
- INSERM UMR1087, LabEx Ion Channels Science and Therapeutics, Institut du Thorax, Nantes, F-44000 France; CNRS, UMR6291, Nantes, F-44000 France; Azm Center for Research in Biotechnology and its Application, Lebanese University, 1300, Tripoli, Lebanon
| | - Marwa Daghsni
- INSERM UMR1087, LabEx Ion Channels Science and Therapeutics, Institut du Thorax, Nantes, F-44000 France; CNRS, UMR6291, Nantes, F-44000 France; Université de Tunis El Manar, Faculté de Médecine de Tunis, LR99ES10 Laboratoire de Génétique Humaine, 1007, Tunis, Tunisia
| | - Stephan De Waard
- INSERM UMR1087, LabEx Ion Channels Science and Therapeutics, Institut du Thorax, Nantes, F-44000 France; CNRS, UMR6291, Nantes, F-44000 France; Université de Nantes, Nantes, F-44000 France
| | - Nathalie Gaborit
- INSERM UMR1087, LabEx Ion Channels Science and Therapeutics, Institut du Thorax, Nantes, F-44000 France; CNRS, UMR6291, Nantes, F-44000 France; Université de Nantes, Nantes, F-44000 France
| | - Ziad Fajloun
- Azm Center for Research in Biotechnology and its Application, Lebanese University, 1300, Tripoli, Lebanon; Faculty of Sciences III, Lebanese University, 1300, Tripoli, Lebanon
| | - Michel Ronjat
- INSERM UMR1087, LabEx Ion Channels Science and Therapeutics, Institut du Thorax, Nantes, F-44000 France; CNRS, UMR6291, Nantes, F-44000 France; Université de Nantes, Nantes, F-44000 France
| | - Yasuo Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Juan L Brusés
- Department of Natural Sciences, Mercy College, Dobbs Ferry, NY 10522, USA
| | - Michel De Waard
- INSERM UMR1087, LabEx Ion Channels Science and Therapeutics, Institut du Thorax, Nantes, F-44000 France; CNRS, UMR6291, Nantes, F-44000 France; Université de Nantes, Nantes, F-44000 France.
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9
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Protein partners of the calcium channel β subunit highlight new cellular functions. Biochem J 2016; 473:1831-44. [DOI: 10.1042/bcj20160125] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 03/15/2016] [Indexed: 12/21/2022]
Abstract
Calcium plays a key role in cell signalling by its intervention in a wide range of physiological processes. Its entry into cells occurs mainly via voltage-gated calcium channels (VGCC), which are found not only in the plasma membrane of excitable cells but also in cells insensitive to electrical signals. VGCC are composed of different subunits, α1, β, α2δ and γ, among which the cytosolic β subunit (Cavβ) controls the trafficking of the channel to the plasma membrane, its regulation and its gating properties. For many years, these were the main functions associated with Cavβ. However, a growing number of proteins have been found to interact with Cavβ, emphasizing the multifunctional role of this versatile protein. Interestingly, some of the newly assigned functions of Cavβ are independent of its role in the regulation of VGCC, and thus further increase its functional roles. Based on the identity of Cavβ protein partners, this review emphasizes the diverse cellular functions of Cavβ and summarizes both past findings as well as recent progress in the understanding of VGCC.
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Campiglio M, Flucher BE. The role of auxiliary subunits for the functional diversity of voltage-gated calcium channels. J Cell Physiol 2015; 230:2019-31. [PMID: 25820299 PMCID: PMC4672716 DOI: 10.1002/jcp.24998] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 03/23/2015] [Indexed: 11/18/2022]
Abstract
Voltage-gated calcium channels (VGCCs) represent the sole mechanism to convert membrane depolarization into cellular functions like secretion, contraction, or gene regulation. VGCCs consist of a pore-forming α1 subunit and several auxiliary channel subunits. These subunits come in multiple isoforms and splice-variants giving rise to a stunning molecular diversity of possible subunit combinations. It is generally believed that specific auxiliary subunits differentially regulate the channels and thereby contribute to the great functional diversity of VGCCs. If auxiliary subunits can associate and dissociate from pre-existing channel complexes, this would allow dynamic regulation of channel properties. However, most auxiliary subunits modulate current properties very similarly, and proof that any cellular calcium channel function is indeed modulated by the physiological exchange of auxiliary subunits is still lacking. In this review we summarize available information supporting a differential modulation of calcium channel functions by exchange of auxiliary subunits, as well as experimental evidence in support of alternative functions of the auxiliary subunits. At the heart of the discussion is the concept that, in their native environment, VGCCs function in the context of macromolecular signaling complexes and that the auxiliary subunits help to orchestrate the diverse protein–protein interactions found in these calcium channel signalosomes. Thus, in addition to a putative differential modulation of current properties, differential subcellular targeting properties and differential protein–protein interactions of the auxiliary subunits may explain the need for their vast molecular diversity. J. Cell. Physiol. 999: 00–00, 2015. © 2015 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc. J. Cell. Physiol. 230: 2019–2031, 2015. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Marta Campiglio
- Division of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| | - Bernhard E Flucher
- Division of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
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11
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Etemad S, Campiglio M, Obermair GJ, Flucher BE. The juvenile myoclonic epilepsy mutant of the calcium channel β(4) subunit displays normal nuclear targeting in nerve and muscle cells. Channels (Austin) 2015; 8:334-43. [PMID: 24875574 PMCID: PMC4203735 DOI: 10.4161/chan.29322] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Voltage-gated calcium channels regulate gene expression by controlling calcium entry through the plasma membrane and by direct interactions of channel fragments and auxiliary β subunits with promoters and the epigenetic machinery in the nucleus. Mutations of the calcium channel β4 subunit gene (CACNB4) cause juvenile myoclonic epilepsy in humans and ataxia and epileptic seizures in mice. Recently a model has been proposed according to which failed nuclear translocation of the truncated β4 subunit R482X mutation resulted in altered transcriptional regulation and consequently in neurological disease. Here we examined the nuclear targeting properties of the truncated β4b(1–481) subunit in tsA-201 cells, skeletal myotubes, and in hippocampal neurons. Contrary to expectation, nuclear targeting of β4b(1–481) was not reduced compared with full-length β4b in any one of the three cell systems. These findings oppose an essential role of the β4 distal C-terminus in nuclear targeting and challenge the idea that the nuclear function of calcium channel β4 subunits is critically involved in the etiology of epilepsy and ataxia in patients and mouse models with mutations in the CACNB4 gene.
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12
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Nakao A, Miki T, Shoji H, Nishi M, Takeshima H, Miyakawa T, Mori Y. Comprehensive behavioral analysis of voltage-gated calcium channel beta-anchoring and -regulatory protein knockout mice. Front Behav Neurosci 2015; 9:141. [PMID: 26136667 PMCID: PMC4468383 DOI: 10.3389/fnbeh.2015.00141] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 05/13/2015] [Indexed: 01/20/2023] Open
Abstract
Calcium (Ca2+) influx through voltage-gated Ca2+ channels (VGCCs) induces numerous intracellular events such as neuronal excitability, neurotransmitter release, synaptic plasticity, and gene regulation. It has been shown that genes related to Ca2+ signaling, such as the CACNA1C, CACNB2, and CACNA1I genes that encode VGCC subunits, are associated with schizophrenia and other psychiatric disorders. Recently, VGCC beta-anchoring and -regulatory protein (BARP) was identified as a novel regulator of VGCC activity via the interaction of VGCC β subunits. To examine the role of the BARP in higher brain functions, we generated BARP knockout (KO) mice and conducted a comprehensive battery of behavioral tests. BARP KO mice exhibited greatly reduced locomotor activity, as evidenced by decreased vertical activity, stereotypic counts in the open field test, and activity level in the home cage, and longer latency to complete a session in spontaneous T-maze alteration test, which reached “study-wide significance.” Acoustic startle response was also reduced in the mutants. Interestingly, they showed multiple behavioral phenotypes that are seemingly opposite to those seen in the mouse models of schizophrenia and its related disorders, including increased working memory, flexibility, prepulse inhibition, and social interaction, and decreased locomotor activity, though many of these phenotypes are statistically weak and require further replications. These results demonstrate that BARP is involved in the regulation of locomotor activity and, possibly, emotionality. The possibility was also suggested that BARP KO mice may serve as a unique tool for investigating the pathogenesis/pathophysiology of schizophrenia and related disorders. Further evaluation of the molecular and physiological phenotypes of the mutant mice would provide new insights into the role of BARP in higher brain functions.
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Affiliation(s)
- Akito Nakao
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University Toyoake, Japan
| | - Takafumi Miki
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Kyoto, Japan
| | - Hirotaka Shoji
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University Toyoake, Japan ; Japan Science and Technology Agency, Core Research for Evolutional Science and Technology Kawaguchi, Japan
| | - Miyuki Nishi
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University Kyoto, Japan
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University Kyoto, Japan
| | - Tsuyoshi Miyakawa
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University Toyoake, Japan ; Japan Science and Technology Agency, Core Research for Evolutional Science and Technology Kawaguchi, Japan ; Section of Behavior Patterns, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences Okazaki, Japan
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Kyoto, Japan
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13
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Garfinkel BP, Melamed-Book N, Anuka E, Bustin M, Orly J. HP1BP3 is a novel histone H1 related protein with essential roles in viability and growth. Nucleic Acids Res 2015; 43:2074-90. [PMID: 25662603 PMCID: PMC4344522 DOI: 10.1093/nar/gkv089] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 12/17/2014] [Accepted: 01/23/2015] [Indexed: 12/28/2022] Open
Abstract
The dynamic architecture of chromatin is vital for proper cellular function, and is maintained by the concerted action of numerous nuclear proteins, including that of the linker histone H1 variants, the most abundant family of nucleosome-binding proteins. Here we show that the nuclear protein HP1BP3 is widely expressed in most vertebrate tissues and is evolutionarily and structurally related to the H1 family. HP1BP3 contains three globular domains and a highly positively charged C-terminal domain, resembling similar domains in H1. Fluorescence recovery after photobleaching (FRAP) studies indicate that like H1, binding of HP1BP3 to chromatin depends on both its C and N terminal regions and is affected by the cell cycle and post translational modifications. HP1BP3 contains functional motifs not found in H1 histones, including an acidic stretch and a consensus HP1-binding motif. Transcriptional profiling of HeLa cells lacking HP1BP3 showed altered expression of 383 genes, suggesting a role for HP1BP3 in modulation of gene expression. Significantly, Hp1bp3(-/-) mice present a dramatic phenotype with 60% of pups dying within 24 h of birth and the surviving animals exhibiting a lifelong 20% growth retardation. We suggest that HP1BP3 is a ubiquitous histone H1 like nuclear protein with distinct and non-redundant functions necessary for survival and growth.
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Affiliation(s)
- Benjamin P Garfinkel
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Naomi Melamed-Book
- Bio-Imaging Unit, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Eli Anuka
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Michael Bustin
- Protein Section, Laboratory of Metabolism, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joseph Orly
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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14
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Mutational Consequences of Aberrant Ion Channels in Neurological Disorders. J Membr Biol 2014; 247:1083-127. [DOI: 10.1007/s00232-014-9716-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 07/25/2014] [Indexed: 12/25/2022]
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15
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Simms BA, Zamponi GW. Neuronal voltage-gated calcium channels: structure, function, and dysfunction. Neuron 2014; 82:24-45. [PMID: 24698266 DOI: 10.1016/j.neuron.2014.03.016] [Citation(s) in RCA: 420] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Voltage-gated calcium channels are the primary mediators of depolarization-induced calcium entry into neurons. There is great diversity of calcium channel subtypes due to multiple genes that encode calcium channel α1 subunits, coassembly with a variety of ancillary calcium channel subunits, and alternative splicing. This allows these channels to fulfill highly specialized roles in specific neuronal subtypes and at particular subcellular loci. While calcium channels are of critical importance to brain function, their inappropriate expression or dysfunction gives rise to a variety of neurological disorders, including, pain, epilepsy, migraine, and ataxia. This Review discusses salient aspects of voltage-gated calcium channel function, physiology, and pathophysiology.
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Affiliation(s)
- Brett A Simms
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
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16
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Xu X, Horne WA. ¹H, ¹³C, and ¹⁵N backbone resonance assignments of the 37 kDa voltage-gated Ca²⁺ channel β4 subunit core SH3-GK domains. BIOMOLECULAR NMR ASSIGNMENTS 2014; 8:217-20. [PMID: 23712306 PMCID: PMC5822721 DOI: 10.1007/s12104-013-9486-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 05/21/2013] [Indexed: 06/02/2023]
Abstract
The β subunit of the voltage-gated Ca(2+) channel (α1, α2δ, and β subunits) is a member of the MAGUK family of proteins and plays an essential role in regulating Ca(2+) channel trafficking and gating. It also serves as a central interaction partner for various Ca(2+) channel regulatory proteins. We report here the nearly complete (1)H, (13)C, and (15)N backbone resonance assignments of the 37 kDa core SH3-GK domains of the β4 subunit. This is the first report of solution assignments for β subunits, and as such will lay the foundation for future investigations of interaction site mapping, functional dynamics, and protein complex structure determination.
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Affiliation(s)
- Xingfu Xu
- Department of Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Rd, Room D208, East Lansing, MI, 48824, USA
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17
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Dawson TF, Boone AN, Senatore A, Piticaru J, Thiyagalingam S, Jackson D, Davison A, Spafford JD. Gene splicing of an invertebrate beta subunit (LCavβ) in the N-terminal and HOOK domains and its regulation of LCav1 and LCav2 calcium channels. PLoS One 2014; 9:e92941. [PMID: 24690951 PMCID: PMC3972191 DOI: 10.1371/journal.pone.0092941] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 02/27/2014] [Indexed: 01/31/2023] Open
Abstract
The accessory beta subunit (Ca(v)β) of calcium channels first appear in the same genome as Ca(v)1 L-type calcium channels in single-celled coanoflagellates. The complexity of this relationship expanded in vertebrates to include four different possible Ca(v)β subunits (β1, β2, β3, β4) which associate with four Ca(v)1 channel isoforms (Ca(v)1.1 to Ca(v)1.4) and three Ca(v)2 channel isoforms (Ca(v)2.1 to Ca(v)2.3). Here we assess the fundamentally-shared features of the Ca(v)β subunit in an invertebrate model (pond snail Lymnaea stagnalis) that bears only three homologous genes: (LCa(v)1, LCa(v)2, and LCa(v)β). Invertebrate Ca(v)β subunits (in flatworms, snails, squid and honeybees) slow the inactivation kinetics of Ca(v)2 channels, and they do so with variable N-termini and lacking the canonical palmitoylation residues of the vertebrate β2a subunit. Alternative splicing of exon 7 of the HOOK domain is a primary determinant of a slow inactivation kinetics imparted by the invertebrate LCa(v)β subunit. LCa(v)β will also slow the inactivation kinetics of LCa(v)3 T-type channels, but this is likely not physiologically relevant in vivo. Variable N-termini have little influence on the voltage-dependent inactivation kinetics of differing invertebrate Ca(v)β subunits, but the expression pattern of N-terminal splice isoforms appears to be highly tissue specific. Molluscan LCa(v)β subunits have an N-terminal "A" isoform (coded by exons: 1a and 1b) that structurally resembles the muscle specific variant of vertebrate β1a subunit, and has a broad mRNA expression profile in brain, heart, muscle and glands. A more variable "B" N-terminus (exon 2) in the exon position of mammalian β3 and has a more brain-centric mRNA expression pattern. Lastly, we suggest that the facilitation of closed-state inactivation (e.g. observed in Ca(v)2.2 and Ca(v)β3 subunit combinations) is a specialization in vertebrates, because neither snail subunit (LCa(v)2 nor LCa(v)β) appears to be compatible with this observed property.
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Affiliation(s)
- Taylor F. Dawson
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Adrienne N. Boone
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Adriano Senatore
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Joshua Piticaru
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | | | - Daniel Jackson
- Institute of Genetics, School of Biology, University of Nottingham, Nottingham, United Kingdom
| | - Angus Davison
- Institute of Genetics, School of Biology, University of Nottingham, Nottingham, United Kingdom
| | - J. David Spafford
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
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18
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Differential neuronal targeting of a new and two known calcium channel β4 subunit splice variants correlates with their regulation of gene expression. J Neurosci 2014; 34:1446-61. [PMID: 24453333 DOI: 10.1523/jneurosci.3935-13.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The β subunits of voltage-gated calcium channels regulate surface expression and gating of CaV1 and CaV2 α1 subunits and thus contribute to neuronal excitability, neurotransmitter release, and calcium-induced gene regulation. In addition, certain β subunits are targeted into the nucleus, where they interact directly with the epigenetic machinery. Whereas their involvement in this multitude of functions is reflected by a great molecular heterogeneity of β isoforms derived from four genes and abundant alternative splicing, little is known about the roles of individual β variants in specific neuronal functions. In the present study, an alternatively spliced β4 subunit lacking the variable N terminus (β4e) is identified. It is highly expressed in mouse cerebellum and cultured cerebellar granule cells (CGCs) and modulates P/Q-type calcium currents in tsA201 cells and CaV2.1 surface expression in neurons. Compared with the other two known full-length β4 variants (β4a and β4b), β4e is most abundantly expressed in the distal axon, but lacks nuclear-targeting properties. To determine the importance of nuclear targeting of β4 subunits for transcriptional regulation, we performed whole-genome expression profiling of CGCs from lethargic (β4-null) mice individually reconstituted with β4a, β4b, and β4e. Notably, the number of genes regulated by each β4 splice variant correlated with the rank order of their nuclear-targeting properties (β4b > β4a > β4e). Together, these findings support isoform-specific functions of β4 splice variants in neurons, with β4b playing a dual role in channel modulation and gene regulation, whereas the newly detected β4e variant serves exclusively in calcium-channel-dependent functions.
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19
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Ronjat M, Kiyonaka S, Barbado M, De Waard M, Mori Y. Nuclear life of the voltage-gated Cacnb4 subunit and its role in gene transcription regulation. Channels (Austin) 2013; 7:119-25. [PMID: 23511121 DOI: 10.4161/chan.23895] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The pore-forming subunit of voltage-gated calcium channels is associated to auxiliary subunits among which the cytoplasmic β subunit. The different isoforms of this subunit control both the plasma membrane targeting and the biophysical properties of the channel moiety. In a recent study, we demonstrated that the Cacnb4 (β 4) isoform is at the center of a new signaling pathway that connects neuronal excitability and gene transcription. This mechanism relies on nuclear targeting of β 4 triggered by neuronal electrical stimulation. This re-localization of β 4 is promoted by its interaction with Ppp2r5d a regulatory subunit of PP2A in complex with PP2A itself. The formation, as well as the nuclear translocation, of the β 4/ Ppp2r5d/ PP2A complex is totally impaired by the premature R482X stops mutation of β 4 that has been previously associated with juvenile epilepsy. Taking as a case study the tyrosine hydroxylase gene that is strongly upregulated in brain of lethargic mice, deficient for β 4 expression, we deciphered the molecular steps presiding to this signaling pathway. Here we show that expression of wild-type β 4 in HEK293 cells results in the regulation of several genes, while expression of the mutated β 4 (β 1-481) produces a different set of gene regulation. Several genes regulated by β 4 in HEK293 cells were also regulated upon neuronal differentiation of NG108-15 cells that induces nuclear translocation of β 4 suggesting a link between β 4 nuclear targeting and gene regulation.
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Affiliation(s)
- Michel Ronjat
- Unité Inserm U836, Grenoble Institute of Neuroscience, La Tronche, France.
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20
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Buraei Z, Yang J. Structure and function of the β subunit of voltage-gated Ca²⁺ channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1530-40. [PMID: 22981275 DOI: 10.1016/j.bbamem.2012.08.028] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 08/22/2012] [Accepted: 08/25/2012] [Indexed: 12/31/2022]
Abstract
The voltage-gated Ca²⁺ channel β subunit (Ca(v)β) is a cytosolic auxiliary subunit that plays an essential role in regulating the surface expression and gating properties of high-voltage activated (HVA) Ca²⁺ channels. It is also crucial for the modulation of HVA Ca²⁺ channels by G proteins, kinases, Ras-related RGK GTPases, and other proteins. There are indications that Ca(v)β may carry out Ca²⁺ channel-independent functions. Ca(v)β knockouts are either non-viable or result in a severe pathophysiology, and mutations in Ca(v)β have been implicated in disease. In this article, we review the structure and various biological functions of Ca(v)β, as well as recent advances. This article is part of a Special Issue entitled: Calcium channels.
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Affiliation(s)
- Zafir Buraei
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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21
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Tadmouri A, Kiyonaka S, Barbado M, Rousset M, Fablet K, Sawamura S, Bahembera E, Pernet-Gallay K, Arnoult C, Miki T, Sadoul K, Gory-Faure S, Lambrecht C, Lesage F, Akiyama S, Khochbin S, Baulande S, Janssens V, Andrieux A, Dolmetsch R, Ronjat M, Mori Y, De Waard M. Cacnb4 directly couples electrical activity to gene expression, a process defective in juvenile epilepsy. EMBO J 2012; 31:3730-44. [PMID: 22892567 DOI: 10.1038/emboj.2012.226] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 07/17/2012] [Indexed: 12/11/2022] Open
Abstract
Calcium current through voltage-gated calcium channels (VGCC) controls gene expression. Here, we describe a novel signalling pathway in which the VGCC Cacnb4 subunit directly couples neuronal excitability to transcription. Electrical activity induces Cacnb4 association to Ppp2r5d, a regulatory subunit of PP2A phosphatase, followed by (i) nuclear translocation of Cacnb4/Ppp2r5d/PP2A, (ii) association with the tyrosine hydroxylase (TH) gene promoter through the nuclear transcription factor thyroid hormone receptor alpha (TRα), and (iii) histone binding through association of Cacnb4 with HP1γ concomitantly with Ser(10) histone H3 dephosphorylation by PP2A. This signalling cascade leads to TH gene repression by Cacnb4 and is controlled by the state of interaction between the SH3 and guanylate kinase (GK) modules of Cacnb4. The human R482X CACNB4 mutation, responsible for a form of juvenile myoclonic epilepsy, prevents association with Ppp2r5 and nuclear targeting of the complex by altering Cacnb4 conformation. These findings demonstrate that an intact VGCC subunit acts as a repressor recruiting platform to control neuronal gene expression.
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Affiliation(s)
- Abir Tadmouri
- Unité Inserm U, Grenoble Institute of Neuroscience, Université Joseph Fourier, La Tronche, France
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22
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Naranjo JR, Mellström B. Ca2+-dependent transcriptional control of Ca2+ homeostasis. J Biol Chem 2012; 287:31674-80. [PMID: 22822058 DOI: 10.1074/jbc.r112.384982] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Intracellular free Ca(2+) ions regulate many cellular functions, and in turn, the cell devotes many genes/proteins to keep tight control of the level of intracellular free Ca(2+). Here, we review recent work on Ca(2+)-dependent mechanisms and effectors that regulate the transcription of genes encoding proteins involved in the maintenance of the homeostasis of Ca(2+) in the cell.
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Affiliation(s)
- Jose R Naranjo
- National Center of Biotechnology, Consejo Superior de Investigaciones Científicas (CSIC) and the Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28049 Madrid, Spain.
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23
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Chernyavskaya Y, Ebert AM, Milligan E, Garrity DM. Voltage-gated calcium channel CACNB2 (β2.1) protein is required in the heart for control of cell proliferation and heart tube integrity. Dev Dyn 2012; 241:648-62. [DOI: 10.1002/dvdy.23746] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2012] [Indexed: 01/11/2023] Open
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24
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Lainé V, Frøkjær-Jensen C, Couchoux H, Jospin M. The alpha1 subunit EGL-19, the alpha2/delta subunit UNC-36, and the beta subunit CCB-1 underlie voltage-dependent calcium currents in Caenorhabditis elegans striated muscle. J Biol Chem 2011; 286:36180-7. [PMID: 21878625 DOI: 10.1074/jbc.m111.256149] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Voltage-gated calcium channels, which play key roles in many physiological processes, are composed of a pore-forming α1 subunit associated with up to three auxiliary subunits. In vertebrates, the role of auxiliary subunits has mostly been studied in heterologous systems, mainly because of the severe phenotypes of knock-out animals. The genetic model Caenorhabditis elegans has all main types of voltage-gated calcium channels and strong loss-of-function mutations in all pore-forming and auxiliary subunits; it is therefore a useful model to investigate the roles of auxiliary subunits in their native context. By recording calcium currents from channel and auxiliary subunit mutants, we molecularly dissected the voltage-dependent calcium currents in striated muscle of C. elegans. We show that EGL-19 is the only α1 subunit that carries calcium currents in muscle cells. We then demonstrate that the α2/δ subunit UNC-36 modulates the voltage dependence, the activation kinetics, and the conductance of calcium currents, whereas another α2/δ subunit TAG-180 has no effect. Finally, we characterize mutants of the two β subunits, CCB-1 and CCB-2. CCB-1 is necessary for viability, and voltage-dependent calcium currents are abolished in the absence of CCB-1 whereas CCB-2 does not affect currents. Altogether these results show that EGL-19, UNC-36, and CCB-1 underlie voltage-dependent calcium currents in C. elegans striated muscle.
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