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Gonzalo-Gobernado R, Moreno-Martínez L, González P, Dopazo XM, Calvo AC, Pidal-Ladrón de Guevara I, Seisdedos E, Díaz-Muñoz R, Mellström B, Osta R, Naranjo JR. Repaglinide Induces ATF6 Processing and Neuroprotection in Transgenic SOD1G93A Mice. Int J Mol Sci 2023; 24:15783. [PMID: 37958767 PMCID: PMC10648964 DOI: 10.3390/ijms242115783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/19/2023] [Accepted: 10/28/2023] [Indexed: 11/15/2023] Open
Abstract
The interaction of the activating transcription factor 6 (ATF6), a key effector of the unfolded protein response (UPR) in the endoplasmic reticulum, with the neuronal calcium sensor Downstream Regulatory Element Antagonist Modulator (DREAM) is a potential therapeutic target in neurodegeneration. Modulation of the ATF6-DREAM interaction with repaglinide (RP) induced neuroprotection in a model of Huntington's disease. Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder with no cure, characterized by the progressive loss of motoneurons resulting in muscle denervation, atrophy, paralysis, and death. The aim of this work was to investigate the potential therapeutic significance of DREAM as a target for intervention in ALS. We found that the expression of the DREAM protein was reduced in the spinal cord of SOD1G93A mice compared to wild-type littermates. RP treatment improved motor strength and reduced the expression of the ALS progression marker collagen type XIXα1 (Col19α1 mRNA) in the quadriceps muscle in SOD1G93A mice. Moreover, treated SOD1G93A mice showed reduced motoneuron loss and glial activation and increased ATF6 processing in the spinal cord. These results indicate that the modulation of the DREAM-ATF6 interaction ameliorates ALS symptoms in SOD1G93A mice.
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Affiliation(s)
- Rafael Gonzalo-Gobernado
- National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain; (R.G.-G.); (P.G.); (X.M.D.); (I.P.-L.d.G.); (E.S.); (R.D.-M.); (B.M.)
- Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28029 Madrid, Spain; (L.M.-M.); (A.C.C.)
| | - Laura Moreno-Martínez
- Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28029 Madrid, Spain; (L.M.-M.); (A.C.C.)
- LAGENBIO, Faculty of Veterinary, University of Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain
- Aragón Health Research Institute (IIS Aragón), Biomedical Research Centre of Aragón (CIBA), 50009 Zaragoza, Spain
- AgriFood Institute of Aragon-IA2 (UNIZAR-CITA), 50013 Zaragoza, Spain
| | - Paz González
- National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain; (R.G.-G.); (P.G.); (X.M.D.); (I.P.-L.d.G.); (E.S.); (R.D.-M.); (B.M.)
- Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28029 Madrid, Spain; (L.M.-M.); (A.C.C.)
| | - Xose Manuel Dopazo
- National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain; (R.G.-G.); (P.G.); (X.M.D.); (I.P.-L.d.G.); (E.S.); (R.D.-M.); (B.M.)
| | - Ana Cristina Calvo
- Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28029 Madrid, Spain; (L.M.-M.); (A.C.C.)
- LAGENBIO, Faculty of Veterinary, University of Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain
- Aragón Health Research Institute (IIS Aragón), Biomedical Research Centre of Aragón (CIBA), 50009 Zaragoza, Spain
- AgriFood Institute of Aragon-IA2 (UNIZAR-CITA), 50013 Zaragoza, Spain
| | - Isabel Pidal-Ladrón de Guevara
- National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain; (R.G.-G.); (P.G.); (X.M.D.); (I.P.-L.d.G.); (E.S.); (R.D.-M.); (B.M.)
| | - Elisa Seisdedos
- National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain; (R.G.-G.); (P.G.); (X.M.D.); (I.P.-L.d.G.); (E.S.); (R.D.-M.); (B.M.)
| | - Rodrigo Díaz-Muñoz
- National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain; (R.G.-G.); (P.G.); (X.M.D.); (I.P.-L.d.G.); (E.S.); (R.D.-M.); (B.M.)
| | - Britt Mellström
- National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain; (R.G.-G.); (P.G.); (X.M.D.); (I.P.-L.d.G.); (E.S.); (R.D.-M.); (B.M.)
- Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28029 Madrid, Spain; (L.M.-M.); (A.C.C.)
| | - Rosario Osta
- Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28029 Madrid, Spain; (L.M.-M.); (A.C.C.)
- LAGENBIO, Faculty of Veterinary, University of Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain
- Aragón Health Research Institute (IIS Aragón), Biomedical Research Centre of Aragón (CIBA), 50009 Zaragoza, Spain
- AgriFood Institute of Aragon-IA2 (UNIZAR-CITA), 50013 Zaragoza, Spain
| | - José Ramón Naranjo
- National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), 28049 Madrid, Spain; (R.G.-G.); (P.G.); (X.M.D.); (I.P.-L.d.G.); (E.S.); (R.D.-M.); (B.M.)
- Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28029 Madrid, Spain; (L.M.-M.); (A.C.C.)
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Burgoyne RD, Helassa N, McCue HV, Haynes LP. Calcium Sensors in Neuronal Function and Dysfunction. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035154. [PMID: 30833454 DOI: 10.1101/cshperspect.a035154] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Calcium signaling in neurons as in other cell types can lead to varied changes in cellular function. Neuronal Ca2+ signaling processes have also become adapted to modulate the function of specific pathways over a wide variety of time domains and these can have effects on, for example, axon outgrowth, neuronal survival, and changes in synaptic strength. Ca2+ also plays a key role in synapses as the trigger for fast neurotransmitter release. Given its physiological importance, abnormalities in neuronal Ca2+ signaling potentially underlie many different neurological and neurodegenerative diseases. The mechanisms by which changes in intracellular Ca2+ concentration in neurons can bring about diverse responses is underpinned by the roles of ubiquitous or specialized neuronal Ca2+ sensors. It has been established that synaptotagmins have key functions in neurotransmitter release, and, in addition to calmodulin, other families of EF-hand-containing neuronal Ca2+ sensors, including the neuronal calcium sensor (NCS) and the calcium-binding protein (CaBP) families, play important physiological roles in neuronal Ca2+ signaling. It has become increasingly apparent that these various Ca2+ sensors may also be crucial for aspects of neuronal dysfunction and disease either indirectly or directly as a direct consequence of genetic variation or mutations. An understanding of the molecular basis for the regulation of the targets of the Ca2+ sensors and the physiological roles of each protein in identified neurons may contribute to future approaches to the development of treatments for a variety of human neuronal disorders.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Nordine Helassa
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Hannah V McCue
- Centre for Genomic Research, University of Liverpool, Liverpool, United Kingdom
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
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Guo YP, Zhi YR, Liu TT, Wang Y, Zhang Y. Global Gene Knockout of Kcnip3 Enhances Pain Sensitivity and Exacerbates Negative Emotions in Rats. Front Mol Neurosci 2019; 12:5. [PMID: 30740043 PMCID: PMC6355686 DOI: 10.3389/fnmol.2019.00005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 01/09/2019] [Indexed: 12/12/2022] Open
Abstract
The Ca2+-binding protein Kv channel interacting protein 3 (KChIP3) or downstream regulatory element antagonist modulator (DREAM), a member of the neuronal calcium sensor (NCS) family, shows remarkable multifunctional properties. It acts as a transcriptional repressor in the nucleus and a modulator of ion channels or receptors, such as Kv4, NMDA receptors and TRPV1 channels on the cytomembrane. Previous studies of Kcnip3-/- mice have indicated that KChIP3 facilitates pain hypersensitivity by repressing Pdyn expression in the spinal cord. Conversely, studies from transgenic daDREAM (dominant active DREAM) mice indicated that KChIP3 contributes to analgesia by repressing Bdnf expression and attenuating the development of central sensitization. To further determine the role of KChIP3 in pain transmission and its possible involvement in emotional processing, we assessed the pain sensitivity and negative emotional behaviors of Kcnip3-/- rats. The knockout rats showed higher pain sensitivity compared to the wild-type rats both in the acute nociceptive pain model and in the late phase (i.e., 2, 4 and 6 days post complete Freund’s adjuvant injection) of the chronic inflammatory pain model. Importantly, Kcnip3-/- rats displayed stronger aversion to the pain-associated compartment, higher anxiety level and aggravated depression-like behavior. Furthermore, RNA-Seq transcriptional profiling of the forebrain cortex were compared between wild-type and Kcnip3-/- rats. Among the 68 upregulated genes, 19 genes (including Nr4a2, Ret, Cplx3, Rgs9, and Itgad) are associated with neural development or synaptic transmission, particularly dopamine neurotransmission. Among the 79 downregulated genes, 16 genes (including Col3a1, Itm2a, Pcdhb3, Pcdhb22, Pcdhb20, Ddc, and Sncaip) are associated with neural development or dopaminergic transmission. Transcriptional upregulation of Nr4a2, Ret, Cplx3 and Rgs9, and downregulation of Col3a1, Itm2a, Pcdhb3 and Ddc, were validated by qPCR analysis. In summary, our studies showed that Kcnip3-/- rats displayed higher pain sensitivity and stronger negative emotions, suggesting an involvement of KChIP3 in negative emotions and possible role in central nociceptive processing.
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Affiliation(s)
- Yu-Peng Guo
- Department of Neurobiology, School of Basic Medical Sciences and Neuroscience Research Institute, Key Laboratory for Neuroscience, Ministry of Education and Ministry of National Health, Peking University, Beijing, China
| | - Yu-Ru Zhi
- Department of Neurobiology, School of Basic Medical Sciences and Neuroscience Research Institute, Key Laboratory for Neuroscience, Ministry of Education and Ministry of National Health, Peking University, Beijing, China
| | - Ting-Ting Liu
- Department of Neurobiology, School of Basic Medical Sciences and Neuroscience Research Institute, Key Laboratory for Neuroscience, Ministry of Education and Ministry of National Health, Peking University, Beijing, China
| | - Yun Wang
- Department of Neurobiology, School of Basic Medical Sciences and Neuroscience Research Institute, Key Laboratory for Neuroscience, Ministry of Education and Ministry of National Health, Peking University, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
| | - Ying Zhang
- Department of Neurobiology, School of Basic Medical Sciences and Neuroscience Research Institute, Key Laboratory for Neuroscience, Ministry of Education and Ministry of National Health, Peking University, Beijing, China
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Benedet T, Gonzalez P, Oliveros JC, Dopazo JM, Ghimire K, Palczewska M, Mellstrom B, Naranjo JR. Transcriptional repressor DREAM regulates trigeminal noxious perception. J Neurochem 2017; 141:544-552. [DOI: 10.1111/jnc.13584] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 02/04/2016] [Accepted: 02/10/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Tomaso Benedet
- National Centre for Biotechnology; C.S.I.C.; Madrid Spain
| | - Paz Gonzalez
- National Centre for Biotechnology; C.S.I.C.; Madrid Spain
- CIBERNED; Madrid Spain
| | | | - Jose M. Dopazo
- National Centre for Biotechnology; C.S.I.C.; Madrid Spain
- CIBERNED; Madrid Spain
| | - Kedar Ghimire
- National Centre for Biotechnology; C.S.I.C.; Madrid Spain
| | | | - Britt Mellstrom
- National Centre for Biotechnology; C.S.I.C.; Madrid Spain
- CIBERNED; Madrid Spain
| | - Jose R. Naranjo
- National Centre for Biotechnology; C.S.I.C.; Madrid Spain
- CIBERNED; Madrid Spain
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Burgoyne RD, Haynes LP. Sense and specificity in neuronal calcium signalling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1921-32. [PMID: 25447549 PMCID: PMC4728190 DOI: 10.1016/j.bbamcr.2014.10.029] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 10/25/2014] [Accepted: 10/29/2014] [Indexed: 11/02/2022]
Abstract
Changes in the intracellular free calcium concentration ([Ca²⁺]i) in neurons regulate many and varied aspects of neuronal function over time scales from microseconds to days. The mystery is how a single signalling ion can lead to such diverse and specific changes in cell function. This is partly due to aspects of the Ca²⁺ signal itself, including its magnitude, duration, localisation and persistent or oscillatory nature. The transduction of the Ca²⁺ signal requires Ca²⁺binding to various Ca²⁺ sensor proteins. The different properties of these sensors are important for differential signal processing and determine the physiological specificity of Ca(2+) signalling pathways. A major factor underlying the specific roles of particular Ca²⁺ sensor proteins is the nature of their interaction with target proteins and how this mediates unique patterns of regulation. We review here recent progress from structural analyses and from functional analyses in model organisms that have begun to reveal the rules that underlie Ca²⁺ sensor protein specificity for target interaction. We discuss three case studies exemplifying different aspects of Ca²⁺ sensor/target interaction. This article is part of a special issue titled the 13th European Symposium on Calcium.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom.
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom
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6
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Localization of Kv4.2 and KChIP2 in lipid rafts and modulation of outward K+ currents by membrane cholesterol content in rat left ventricular myocytes. Pflugers Arch 2014; 467:299-309. [DOI: 10.1007/s00424-014-1521-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 04/11/2014] [Accepted: 04/15/2014] [Indexed: 02/03/2023]
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Wang T, Cheng Y, Dou Y, Goonesekara C, David JP, Steele DF, Huang C, Fedida D. Trafficking of an endogenous potassium channel in adult ventricular myocytes. Am J Physiol Cell Physiol 2012; 303:C963-76. [PMID: 22914645 DOI: 10.1152/ajpcell.00217.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The roles of several small GTPases in the expression of an endogenous potassium current, I(to,f), in adult rat ventricular myocytes have been investigated. The results indicate that forward trafficking of newly synthesized Kv4.2, which underlies I(to,f) in these cells, requires both Rab1 and Sar1 function. Expression of a Rab1 dominant negative (DN) reduced I(to,f) current density by roughly one-half relative to control, mCherry-transfected myocytes. Similarly, expression of a Sar1DN nearly halved I(to,f) current density. Rab11 is not essential to trafficking of Kv4.2, as expression of a Rab11DN had no effect on I(to,f) over the time frames investigated here. In a process dependent on intact endoplasmic reticulum (ER)-to-Golgi transport, however, overexpression of wild-type Rab11 resulted in a doubling of I(to,f) density; block of ER-to-Golgi traffic by Brefeldin A completely abrogated the effect. Also implicated in the trafficking of Kv4.2 are Rab5 and Rab4. Rab5DN expression increased endogenous I(to,f) by two- to threefold, nonadditively with inhibition of dynamin-dependent endocytosis. And, in a phenomenon similar to that previously reported for myoblast-expressed Kv1.5, Rab4DN expression roughly doubled endogenous peak transient currents. Colocalization experiments confirmed the involvement of Rab4 in postinternalization trafficking of Kv4.2. There was little role evident for the lysosome in the degradation of internalized Kv4.2, as overexpression of neither wild-type nor DN isoforms of Rab7 had any effect on I(to,f). Instead, degradation may depend largely on the proteasome; the proteasome inhibitor MG132 significantly increased I(to,f) density.
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Affiliation(s)
- Tiantian Wang
- Dept. of Anesthesiology, Pharmacology and Therapeutics, Univ. of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3.
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Burgoyne RD, Haynes LP. Understanding the physiological roles of the neuronal calcium sensor proteins. Mol Brain 2012; 5:2. [PMID: 22269068 PMCID: PMC3271974 DOI: 10.1186/1756-6606-5-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 01/23/2012] [Indexed: 01/22/2023] Open
Abstract
Calcium signalling plays a crucial role in the control of neuronal function and plasticity. Changes in neuronal Ca2+ concentration are detected by Ca2+-binding proteins that can interact with and regulate target proteins to modify their function. Members of the neuronal calcium sensor (NCS) protein family have multiple non-redundant roles in the nervous system. Here we review recent advances in the understanding of the physiological roles of the NCS proteins and the molecular basis for their specificity.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.
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Savignac M, Mellström B, Bébin AG, Oliveros JC, Delpy L, Pinaud E, Naranjo JR. Increased B cell proliferation and reduced Ig production in DREAM transgenic mice. THE JOURNAL OF IMMUNOLOGY 2010; 185:7527-36. [PMID: 21059893 DOI: 10.4049/jimmunol.1000152] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
DREAM/KChIP-3 is a calcium-dependent transcriptional repressor highly expressed in immune cells. Transgenic mice expressing a dominant active DREAM mutant show reduced serum Ig levels. In vitro assays show that reduced Ig secretion is an intrinsic defect of transgenic B cells that occurs without impairment in plasma cell differentiation, class switch recombination, or Ig transcription. Surprisingly, transgenic B cells show an accelerated entry in cell division. Transcriptomic analysis of transgenic B cells revealed that hyperproliferative B cell response could be correlated with a reduced expression of Klf9, a cell-cycle regulator. Pulse-chase experiments demonstrated that the defect in Ig production is associated with reduced translation rather than with increased protein degradation. Importantly, transgenic B cells showed reduced expression of the Eif4g3 gene, which encodes a protein related to protein translation. Our results disclose, to our knowledge, a novel function of DREAM in proliferation and Ig synthesis in B lymphocytes.
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Affiliation(s)
- Magali Savignac
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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McCue HV, Haynes LP, Burgoyne RD. The diversity of calcium sensor proteins in the regulation of neuronal function. Cold Spring Harb Perspect Biol 2010; 2:a004085. [PMID: 20668007 DOI: 10.1101/cshperspect.a004085] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Calcium signaling in neurons as in other cell types mediates changes in gene expression, cell growth, development, survival, and cell death. However, neuronal Ca(2+) signaling processes have become adapted to modulate the function of other important pathways including axon outgrowth and changes in synaptic strength. Ca(2+) plays a key role as the trigger for fast neurotransmitter release. The ubiquitous Ca(2+) sensor calmodulin is involved in various aspects of neuronal regulation. The mechanisms by which changes in intracellular Ca(2+) concentration in neurons can bring about such diverse responses has, however, become a topic of widespread interest that has recently focused on the roles of specialized neuronal Ca(2+) sensors. In this article, we summarize synaptotagmins in neurotransmitter release, the neuronal roles of calmodulin, and the functional significance of the NCS and the CaBP/calneuron protein families of neuronal Ca(2+) sensors.
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Affiliation(s)
- Hannah V McCue
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, United Kingdom
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11
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Abstract
Since the first discovery of Kvbeta-subunits more than 15 years ago, many more ancillary Kv channel subunits were characterized, for example, KChIPs, KCNEs, and BKbeta-subunits. The ancillary subunits are often integral parts of native Kv channels, which, therefore, are mostly multiprotein complexes composed of voltage-sensing and pore-forming Kvalpha-subunits and of ancillary or beta-subunits. Apparently, Kv channels need the ancillary subunits to fulfill their many different cell physiological roles. This is reflected by the large structural diversity observed with ancillary subunit structures. They range from proteins with transmembrane segments and extracellular domains to purely cytoplasmic proteins. Ancillary subunits modulate Kv channel gating but can also have a great impact on channel assembly, on channel trafficking to and from the cellular surface, and on targeting Kv channels to different cellular compartments. The importance of the role of accessory subunits is further emphasized by the number of mutations that are associated in both humans and animals with diseases like hypertension, epilepsy, arrhythmogenesis, periodic paralysis, and hypothyroidism. Interestingly, several ancillary subunits have in vitro enzymatic activity; for example, Kvbeta-subunits are oxidoreductases, or modulate enzymatic activity, i.e., KChIP3 modulates presenilin activity. Thus different modes of beta-subunit association and of functional impact on Kv channels can be delineated, making it difficult to extract common principles underlying Kvalpha- and beta-subunit interactions. We critically review present knowledge on the physiological role of ancillary Kv channel subunits and their effects on Kv channel properties.
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Affiliation(s)
- Olaf Pongs
- Institut für Neurale Signalverarbeitung, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Universität Hamburg, Hamburg, Germany.
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12
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Anderson D, Mehaffey WH, Iftinca M, Rehak R, Engbers JDT, Hameed S, Zamponi GW, Turner RW. Regulation of neuronal activity by Cav3-Kv4 channel signaling complexes. Nat Neurosci 2010; 13:333-7. [PMID: 20154682 DOI: 10.1038/nn.2493] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 12/14/2009] [Indexed: 11/09/2022]
Abstract
Kv4 low voltage-activated A-type potassium channels are widely expressed in excitable cells, where they control action potential firing, dendritic activity and synaptic integration. Kv4 channels exist as a complex that includes K(+) channel-interacting proteins (KChIPs), which contain calcium-binding domains and therefore have the potential to confer calcium dependence on the Kv4 channel. We found that T-type calcium channels and Kv4 channels form a signaling complex in rat that efficiently couples calcium influx to KChIP3 to modulate Kv4 function. This interaction was critical for allowing Kv4 channels to function in the subthreshold membrane potential range to regulate neuronal firing properties. The widespread expression of these channels and accessory proteins indicates that the Cav3-Kv4 signaling complex is important for the function of a wide range of electrically excitable cells.
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Affiliation(s)
- Dustin Anderson
- Department of Physiology & Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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13
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Kv channel interacting protein 3 expression and regulation by haloperidol in midbrain dopaminergic neurons. Brain Res 2009; 1304:1-13. [DOI: 10.1016/j.brainres.2009.09.045] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 09/10/2009] [Accepted: 09/14/2009] [Indexed: 01/29/2023]
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14
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Thomsen MB, Wang C, Ozgen N, Wang HG, Rosen MR, Pitt GS. Accessory subunit KChIP2 modulates the cardiac L-type calcium current. Circ Res 2009; 104:1382-9. [PMID: 19461043 DOI: 10.1161/circresaha.109.196972] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Complex modulation of voltage-gated Ca2+ currents through the interplay among Ca2+ channels and various Ca(2+)-binding proteins is increasingly being recognized. The K+ channel interacting protein 2 (KChIP2), originally identified as an auxiliary subunit for K(V)4.2 and a component of the transient outward K+ channel (I(to)), is a Ca(2+)-binding protein whose regulatory functions do not appear restricted to K(V)4.2. Consequently, we hypothesized that KChIP2 is a direct regulator of the cardiac L-type Ca2+ current (I(Ca,L)). We found that I(Ca,L) density from KChIP2(-/-) myocytes is reduced by 28% compared to I(Ca,L) recorded from wild-type myocytes (P<0.05). This reduction in current density results from loss of a direct effect on the Ca2+ channel current, as shown in a transfected cell line devoid of confounding cardiac ion currents. I(Ca,L) regulation by KChIP2 was independent of Ca2+ binding to KChIP2. Biochemical analysis suggested a direct interaction between KChIP2 and the Ca(V)1.2 alpha(1C) subunit N terminus. We found that KChIP2 binds to the N-terminal inhibitory module of alpha(1C) and augments I(Ca,L) current density without increasing Ca(V)1.2 protein expression or trafficking to the plasma membrane. We propose a model in which KChIP2 impedes the N-terminal inhibitory module of Ca(V)1.2, resulting in increased I(Ca,L). In the context of recent reports that KChIP2 modulates multiple K(V) and Na(V) currents, these results suggest that KChIP2 is a multimodal regulator of cardiac ionic currents.
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Affiliation(s)
- Morten B Thomsen
- Department of Medicine, Duke University Medical Center, Box 103030 Medical Center, Durham, NC 27710, USA
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A VAMP7/Vti1a SNARE complex distinguishes a non-conventional traffic route to the cell surface used by KChIP1 and Kv4 potassium channels. Biochem J 2009; 418:529-40. [PMID: 19138172 PMCID: PMC2650881 DOI: 10.1042/bj20081736] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The KChIPs (K(+) channel-interacting proteins) are EF hand-containing proteins required for the traffic of channel-forming Kv4 K(+) subunits to the plasma membrane. KChIP1 is targeted, through N-terminal myristoylation, to intracellular vesicles that appear to be trafficking intermediates from the ER (endoplasmic reticulum) to the Golgi but differ from those underlying conventional ER-Golgi traffic. To define KChIP1 vesicles and the traffic pathway followed by Kv4/KChIP1 traffic, we examined their relationship to potential SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) proteins mediating the trafficking step. To distinguish Kv4/KChIP1 from conventional constitutive traffic, we compared it to the traffic of the VSVG (vesicular-stomatitis virus G-protein). Expression of KChIP with single or triple EF hand mutations quantitatively inhibited Kv4/KChIP1 traffic to the cell surface but had no effect on VSVG traffic. KChIP1-expressing vesicles co-localized with the SNARE proteins Vti1a and VAMP7 (vesicle-associated membrane protein 7), but not with the components of two other ER-Golgi SNARE complexes. siRNA (small interfering RNA)-mediated knockdown of Vti1a or VAMP7 inhibited Kv4/KChIP1traffic to the plasma membrane in HeLa and Neuro2A cells. Vti1a and VAMP7 siRNA had no effect on VSVG traffic or that of Kv4.2 when stimulated by KChIP2, a KChIP with different intrinsic membrane targeting compared with KChIP1. The present results suggest that a SNARE complex containing VAMP7 and Vti1a defines a novel traffic pathway to the cell surface in both neuronal and non-neuronal cells.
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