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Bkaily G, Jacques D. Calcium Homeostasis, Transporters, and Blockers in Health and Diseases of the Cardiovascular System. Int J Mol Sci 2023; 24:ijms24108803. [PMID: 37240147 DOI: 10.3390/ijms24108803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/06/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
Calcium is a highly positively charged ionic species. It regulates all cell types' functions and is an important second messenger that controls and triggers several mechanisms, including membrane stabilization, permeability, contraction, secretion, mitosis, intercellular communications, and in the activation of kinases and gene expression. Therefore, controlling calcium transport and its intracellular homeostasis in physiology leads to the healthy functioning of the biological system. However, abnormal extracellular and intracellular calcium homeostasis leads to cardiovascular, skeletal, immune, secretory diseases, and cancer. Therefore, the pharmacological control of calcium influx directly via calcium channels and exchangers and its outflow via calcium pumps and uptake by the ER/SR are crucial in treating calcium transport remodeling in pathology. Here, we mainly focused on selective calcium transporters and blockers in the cardiovascular system.
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Affiliation(s)
- Ghassan Bkaily
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Danielle Jacques
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
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2
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Nagata A, Tagashira H, Kita S, Kita T, Nakajima N, Abe K, Iwasaki A, Iwamoto T. Genetic knockout and pharmacologic inhibition of NCX1 attenuate hypoxia-induced pulmonary arterial hypertension. Biochem Biophys Res Commun 2020; 529:793-798. [PMID: 32736709 DOI: 10.1016/j.bbrc.2020.06.045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 06/10/2020] [Indexed: 11/30/2022]
Abstract
The Na+/Ca2+ exchanger type-1 (NCX1) is a bidirectional transporter that is controlled by membrane potential and transmembrane gradients of Na+ and Ca2+. Vascular smooth muscle NCX1 plays an important role in intracellular Ca2+ homeostasis and Ca2+ signaling. We found that NCX1 was upregulated in the pulmonary arteries of mice exposed to chronic hypoxia (10% O2 for 4 weeks). Hence, we investigated the pathophysiological role of NCX1 in hypoxia-induced pulmonary arterial hypertension (PAH), using NCX1-heterozygous (NCX1+/-) mice, in which NCX1 expression is reduced by half, and SEA0400, a specific NCX1 inhibitor. NCX1+/- mice exhibited attenuation of hypoxia-induced PAH and right ventricular (RV) hypertrophy compared with wild-type mice. Furthermore, continuous administration of SEA0400 (0.5 mg/kg/day for 4 weeks) to wild-type mice by osmotic pumps significantly suppressed hypoxia-induced PAH and pulmonary vessel muscularization, with a slight reduction in RV hypertrophy. These findings indicate that the upregulation of NCX1 contributes to the development of hypoxia-induced PAH, suggesting that NCX1 inhibition might be a novel approach for the treatment of PAH.
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Affiliation(s)
- Asahi Nagata
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan; Department of General Thoracic, Breast and Pediatric Surgery, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Hideaki Tagashira
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Satomi Kita
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan; Department of Pharmacology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan.
| | - Tomo Kita
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Naoko Nakajima
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Kohtaro Abe
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Akinori Iwasaki
- Department of General Thoracic, Breast and Pediatric Surgery, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Takahiro Iwamoto
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
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3
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Kohajda Z, Loewe A, Tóth N, Varró A, Nagy N. The Cardiac Pacemaker Story-Fundamental Role of the Na +/Ca 2+ Exchanger in Spontaneous Automaticity. Front Pharmacol 2020; 11:516. [PMID: 32410993 PMCID: PMC7199655 DOI: 10.3389/fphar.2020.00516] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 04/01/2020] [Indexed: 01/01/2023] Open
Abstract
The electrophysiological mechanism of the sinus node automaticity was previously considered exclusively regulated by the so-called "funny current". However, parallel investigations increasingly emphasized the importance of the Ca2+-homeostasis and Na+/Ca2+ exchanger (NCX). Recently, increasing experimental evidence, as well as insight through mechanistic in silico modeling demonstrates the crucial role of the exchanger in sinus node pacemaking. NCX had a key role in the exciting story of discovery of sinus node pacemaking mechanisms, which recently settled with a consensus on the coupled-clock mechanism after decades of debate. This review focuses on the role of the Na+/Ca2+ exchanger from the early results and concepts to recent advances and attempts to give a balanced summary of the characteristics of the local, spontaneous, and rhythmic Ca2+ releases, the molecular control of the NCX and its role in the fight-or-flight response. Transgenic animal models and pharmacological manipulation of intracellular Ca2+ concentration and/or NCX demonstrate the pivotal function of the exchanger in sinus node automaticity. We also highlight where specific hypotheses regarding NCX function have been derived from computational modeling and require experimental validation. Nonselectivity of NCX inhibitors and the complex interplay of processes involved in Ca2+ handling render the design and interpretation of these experiments challenging.
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Affiliation(s)
- Zsófia Kohajda
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary.,Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Axel Loewe
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Noémi Tóth
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - András Varró
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary.,Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Norbert Nagy
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary.,Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
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4
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Scranton K, John S, Escobar A, Goldhaber JI, Ottolia M. Modulation of the cardiac Na +-Ca 2+ exchanger by cytoplasmic protons: Molecular mechanisms and physiological implications. Cell Calcium 2019; 87:102140. [PMID: 32070924 DOI: 10.1016/j.ceca.2019.102140] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/06/2019] [Accepted: 12/07/2019] [Indexed: 01/31/2023]
Abstract
A precise temporal and spatial control of intracellular Ca2+ concentration is essential for a coordinated contraction of the heart. Following contraction, cardiac cells need to rapidly remove intracellular Ca2+ to allow for relaxation. This task is performed by two transporters: the plasma membrane Na+-Ca2+ exchanger (NCX) and the sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA). NCX extrudes Ca2+ from the cell, balancing the Ca2+entering the cytoplasm during systole through L-type Ca2+ channels. In parallel, following SR Ca2+ release, SERCA activity replenishes the SR, reuptaking Ca2+ from the cytoplasm. The activity of the mammalian exchanger is fine-tuned by numerous ionic allosteric regulatory mechanisms. Micromolar concentrations of cytoplasmic Ca2+ potentiate NCX activity, while an increase in intracellular Na+ levels inhibits NCX via a mechanism known as Na+-dependent inactivation. Protons are also powerful inhibitors of NCX activity. By regulating NCX activity, Ca2+, Na+ and H+ couple cell metabolism to Ca2+ homeostasis and therefore cardiac contractility. This review summarizes the recent progress towards the understanding of the molecular mechanisms underlying the ionic regulation of the cardiac NCX with special emphasis on pH modulation and its physiological impact on the heart.
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Affiliation(s)
- Kyle Scranton
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Scott John
- Department of Medicine (Cardiology), UCLA, Los Angeles, CA 90095, USA; Cardiovascular Research Laboratory, UCLA, Los Angeles, CA 90095, USA
| | - Ariel Escobar
- Department of Bioengineering, School of Engineering, UC Merced, Merced, CA 95343, USA
| | - Joshua I Goldhaber
- Smidt Heart Institute, Cedars Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Michela Ottolia
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, UCLA, Los Angeles, CA 90095, USA; Cardiovascular Research Laboratory, UCLA, Los Angeles, CA 90095, USA.
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5
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Monteiro DA, Kalinin AL, Selistre-de-Araújo HS, Nogueira LAN, Beletti ME, Fernandes MN, Rantin FT. Cardioprotective effects of alternagin-C (ALT-C), a disintegrin-like protein from Rhinocerophis alternatus snake venom, on hypoxia-reoxygenation-induced injury in fish. Comp Biochem Physiol C Toxicol Pharmacol 2019; 215:67-75. [PMID: 30352307 DOI: 10.1016/j.cbpc.2018.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 10/10/2018] [Indexed: 10/28/2022]
Abstract
Alternagin-C (ALT-C) is a disintegrin-like peptide purified from Rhinocerophis alternatus snake venom with the property of inducing vascular endothelial growth factor (VEGF) expression, endothelial cell proliferation and migration, and angiogenesis. Therefore, this protein could be interesting as a new approach for ischemic heart diseases, an imbalance between myocardial oxygen supply and demand, leading to cardiac dysfunction. We investigated the effects of a single dose of alternagin-C (0.5 mg kg-1, via intra-arterial), after 7 days, on hypoxia/reoxygenation challenge in isolated ventricle strips and on morphological changes and density of blood vessels of the heart, using fish as an alternative experimental model. ALT-C treatment provided protection of cardiomyocytes against hypoxia/reoxygenation-induced negative inotropism. ALT-C also stimulated angiogenesis and improved excitation-contraction coupling during hypoxic conditions. Our results provide a new insight into a functional role of ALT-C against hypoxia/reoxygenation-induced cardiomyocyte injury pointing out to a potential therapeutic strategy for ischemia-related diseases.
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Affiliation(s)
- D A Monteiro
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil.
| | - A L Kalinin
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
| | - H S Selistre-de-Araújo
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
| | - L A N Nogueira
- Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, MG, Brazil
| | - M E Beletti
- Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, MG, Brazil
| | - M N Fernandes
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
| | - F T Rantin
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
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6
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Moriguchi S, Kita S, Inagaki R, Yabuki Y, Sasaki Y, Ishikawa S, Sakagami H, Iwamoto T, Fukunaga K. Aberrant Amygdala-Dependent Cued Fear Memory in Na +/Ca 2+ Exchanger 1 Heterozygous Mice. Mol Neurobiol 2018; 56:4381-4394. [PMID: 30324228 DOI: 10.1007/s12035-018-1384-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 10/08/2018] [Indexed: 02/06/2023]
Abstract
Na+/Ca2+ exchangers (NCXs) are mainly expressed in the plasma membrane and exchange one Ca2+ for three Na+, depending on the electrochemical gradients across the plasma membrane. NCXs have three isoforms, NCX1-3, encoded by distinct genes in mammals. Here, we report that heterozygous mice lacking NCX1 (NCX1+/-) exhibit impaired amygdala-dependent cued fear memory. NCX1+/- mice showed significant impairment in fear-related behaviors measured with the elevated-plus maze, light-dark, open-field, and marble-burying tasks. In addition, NCX1+/- mice showed abnormality in cued fear memory but not in contextual fear memory in a fear-conditioning task. In immunohistochemical analyses, NCX1+/- mice had significantly increased number of c-Fos-positive cells in the lateral amygdala (LA) but not in the central amygdala following fear-related tone stimuli. c-Fos expression peaked at 1 h. In concordance with the aberrant fear-related behaviors in NCX1+/- mice, enhanced long-term potentiation was also observed in the LA of these mice. Furthermore, enhancement of CaMKII or CaMKIV activity in the LA was observed in NCX1+/- mice by immunoblot analyses. In contrast, CaMKII+/- but not CaMKIV-/- mice insufficiently exhibited tone-induced cued fear memory and there was no increase in the number of c-Fos-positive cells in the LA. Altogether, the increased CaMKII activity and consequent c-Fos expression likely account for the dysregulation of amygdala-dependent cued fear memory in NCX1+/- mice.
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Affiliation(s)
- Shigeki Moriguchi
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan.
| | - Satomi Kita
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, 7-45-1, Nanakuma, Jonan-ku, Fukuoka, Fukuoka, 814-0180, Japan.,Department of Pharmacology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Ryo Inagaki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Yasushi Yabuki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Yuzuru Sasaki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Shun Ishikawa
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Takahiro Iwamoto
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, 7-45-1, Nanakuma, Jonan-ku, Fukuoka, Fukuoka, 814-0180, Japan.
| | - Kohji Fukunaga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
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7
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Lubelwana Hafver T, Wanichawan P, Manfra O, de Souza GA, Lunde M, Martinsen M, Louch WE, Sejersted OM, Carlson CR. Mapping the in vitro interactome of cardiac sodium (Na + )-calcium (Ca 2+ ) exchanger 1 (NCX1). Proteomics 2017; 17. [PMID: 28755400 DOI: 10.1002/pmic.201600417] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 07/03/2017] [Accepted: 07/26/2017] [Indexed: 11/07/2022]
Abstract
The sodium (Na+ )-calcium (Ca2+ ) exchanger 1 (NCX1) is an antiporter membrane protein encoded by the SLC8A1 gene. In the heart, it maintains cytosolic Ca2+ homeostasis, serving as the primary mechanism for Ca2+ extrusion during relaxation. Dysregulation of NCX1 is observed in end-stage human heart failure. In this study, we used affinity purification coupled with MS in rat left ventricle lysates to identify novel NCX1 interacting proteins in the heart. Two screens were conducted using: (1) anti-NCX1 against endogenous NCX1 and (2) anti-His (where His is histidine) with His-trigger factor-NCX1cyt recombinant protein as bait. The respective methods identified 112 and 350 protein partners, of which several were known NCX1 partners from the literature, and 29 occurred in both screens. Ten novel protein partners (DYRK1A, PPP2R2A, SNTB1, DMD, RABGGTA, DNAJB4, BAG3, PDE3A, POPDC2, STK39) were validated for binding to NCX1, and two partners (DYRK1A, SNTB1) increased NCX1 activity when expressed in HEK293 cells. A cardiac NCX1 protein-protein interaction map was constructed. The map was highly connected, containing distinct clusters of proteins with different biological functions, where "cell communication" and "signal transduction" formed the largest clusters. The NCX1 interactome was also significantly enriched with proteins/genes involved in "cardiovascular disease" which can be explored as novel drug targets in future research.
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Affiliation(s)
- Tandekile Lubelwana Hafver
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Pimthanya Wanichawan
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Ornella Manfra
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Gustavo Antonio de Souza
- Department of Immunology and Centre for Immune Regulation, Oslo University Hospital HF Rikshospitalet, University of Oslo, Oslo, Norway.,The Brain Institute, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.,Bioinformatics Multidisciplinary Environment, Instituto Metrópole Digital, UFRN, Natal, RN, Brazil
| | - Marianne Lunde
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Marita Martinsen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - William Edward Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Ole Mathias Sejersted
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Cathrine Rein Carlson
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
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8
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Reduced expression of Na +/Ca 2+ exchangers is associated with cognitive deficits seen in Alzheimer's disease model mice. Neuropharmacology 2017; 131:291-303. [PMID: 29274751 DOI: 10.1016/j.neuropharm.2017.12.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 12/08/2017] [Accepted: 12/20/2017] [Indexed: 11/21/2022]
Abstract
Na+/Ca2+ exchangers (NCXs) are expressed primarily in the plasma membrane of most cell types, where they mediate electrogenic exchange of one Ca2+ for three Na+ ions, depending on Ca2+ and Na+ electrochemical gradients across the membrane. Three mammalian NCX isoforms (NCX1, NCX2, and NCX3) are each encoded by a distinct gene. Here, we report that NCX2 and NCX3 protein and mRNA levels are relatively reduced in hippocampal CA1 of APP23 and APP-KI mice. Likewise, NCX2+/- or NCX3+/- mice exhibited impaired hippocampal LTP and memory-related behaviors. Moreover, relative to controls, calcium/calmodulin-dependent protein kinase II (CaMKII) autophosphorylation significantly decreased in NCX2+/- mouse hippocampus but increased in hippocampus of NCX3+/- mice. NCX2 or NCX3 heterozygotes displayed impaired maintenance of hippocampal LTP, a phenotype that in NCX2+/- mice was correlated with elevated calcineurin activity and rescued by treatment with the calcineurin (CaN) inhibitor FK506. Likewise, FK506 treatment significantly restored impaired hippocampal LTP in APP-KI mice. Moreover, Ca2+ clearance after depolarization following high frequency stimulation was slightly delayed in hippocampal CA1 regions of NCX2+/- mice. Electron microscopy revealed relatively decreased synaptic density in CA1 of NCX2+/- mice, while the number of spines with perforated synapses in CA1 significantly increased in NCX3+/- mice. We conclude that memory impairment seen in NCX2+/- and NCX3+/- mice reflect dysregulated hippocampal CaMKII activity, which alters dendritic spine morphology, findings with implications for memory deficits seen in Alzheimer's disease model mice.
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9
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Nishiyama K, Tanioka K, Azuma YT, Hayashi S, Fujimoto Y, Yoshida N, Kita S, Suzuki S, Nakajima H, Iwamoto T, Takeuchi T. Na +/Ca 2+ exchanger contributes to stool transport in mice with experimental diarrhea. J Vet Med Sci 2016; 79:403-411. [PMID: 27928109 PMCID: PMC5326949 DOI: 10.1292/jvms.16-0475] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The Na+/Ca2+ exchanger (NCX) is a bidirectional transporter that is
controlled by membrane potential and transmembrane gradients of Na+ and
Ca2+. To reveal the functional role of NCX on gastrointestinal motility, we
have previously used NCX1 and NCX2 heterozygote knockout mice (HET). We found that NCX1
and NCX2 play important roles in the motility of the gastric fundus, ileum and distal
colon. Therefore, we believed that NCX1 and NCX2 play an important role in transport of
intestinal contents. Here, we investigated the role of NCX in a mouse model of
drug-induced diarrhea. The fecal consistencies in NCX1 HET and NCX2 HET were assessed
using a diarrhea induced by magnesium sulfate, 5-hydroxytryptamine (5-HT) and
prostaglandin E2 (PGE2). NCX2 HET, but not NCX1 HET, exacerbated
magnesium sulfate-induced diarrhea by increasing watery fecals. Likewise, 5-HT-induced
diarrheas were exacerbated in NCX2 HET, but not NCX1 HET. However, NCX1 HET and NCX2 HET
demonstrated PGE2 induced diarrhea similar to those of wild-type mice (WT). As
well as the result of the distal colon shown previously, in the proximal and transverse
colons of WT, the myenteric plexus layers and the longitudinal and circular muscle layers
were strongly immunoreactive to NCX1 and NCX2. In this study, we demonstrate that NCX2 has
important roles in development of diarrhea.
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Affiliation(s)
- Kazuhiro Nishiyama
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, 1-58 Rinku-ohraikita, Izumisano, Osaka 598-8531, Japan
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10
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Roles of Na+/Ca2+ exchanger isoforms NCX1 and NCX2 in motility in mouse ileum. Naunyn Schmiedebergs Arch Pharmacol 2016; 389:1081-90. [DOI: 10.1007/s00210-016-1271-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 07/03/2016] [Indexed: 12/13/2022]
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11
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Azuma YT, Hayashi S, Nishiyama K, Kita S, Mukai K, Nakajima H, Iwamoto T, Takeuchi T. Na(+) /Ca(2+) exchanger-heterozygote knockout mice display increased relaxation in gastric fundus and accelerated gastric transit in vivo. Neurogastroenterol Motil 2016; 28:827-36. [PMID: 26787195 DOI: 10.1111/nmo.12779] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/25/2015] [Indexed: 01/31/2023]
Abstract
BACKGROUND For the contraction and relaxation of gastric smooth muscles to occur, the intracellular Ca(2+) concentration must be increased and decreased, respectively. The Na(+) /Ca(2+) exchanger (NCX) is a plasma membrane transporter that is involved in regulating intracellular Ca(2+) concentrations. METHODS To determine the role of NCX in gastrointestinal tissues, we examined electric field stimulation (EFS)-induced relaxations in the circular muscles of the gastric fundus in NCX1 and NCX2 heterozygote knockout mice (HET). KEY RESULTS The myenteric plexus layers and the longitudinal and circular muscle layers in the gastric fundus of wild-type mice (WT) were strongly immunoreactive to NCX1 and NCX2. EFS induced a transient relaxation that was apparent during the stimulus and a sustained relaxation that persisted after the end of the stimulus. The amplitudes of EFS-induced transient relaxation and sustained relaxation were greater in NCX1 HET and NCX2 HET than in WT. When an inhibitor of nitric oxide synthase was added following the EFS, neither NCX1 HET nor NCX2 HET exhibited transient relaxation, similar to WT. Furthermore, when a PACAP antagonist was added following the EFS, sustained relaxation in NCX1 HET and NCX2 HET was not observed, similar to WT. Next, we examined the effect of NCX heterozygous deficiency on relaxation in response to NO and PACAP in smooth muscles. The magnitude of NOR-1- and PACAP-induced relaxations in NCX1 HET and NCX2 HET was similar to that of WT. CONCLUSIONS & INFERENCES In this study, we demonstrate that NCX1 and NCX2 expressed in neurons regulate the motility in the gastric fundus.
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Affiliation(s)
- Y T Azuma
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - S Hayashi
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - K Nishiyama
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - S Kita
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - K Mukai
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - H Nakajima
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - T Iwamoto
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - T Takeuchi
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
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12
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Morita M, Nakane A, Maekawa S, Kudo Y. Pharmacological characterization of the involvement of protein kinase C in oscillatory and non-oscillatory calcium increases in astrocytes. J Pharmacol Sci 2015; 129:38-42. [PMID: 26349942 DOI: 10.1016/j.jphs.2015.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 08/09/2015] [Accepted: 08/11/2015] [Indexed: 01/24/2023] Open
Abstract
Evidence increasingly shows that astrocytes play a pivotal role in brain physiology and pathology via calcium dependent processes, thus the characterization of the calcium dynamics in astrocytes is of growing importance. We have previously reported that the epidermal growth factor and basic fibroblast growth factor up-regulate the oscillation of the calcium releases that are induced by stimuli, including glutamate in cultured astrocytes. This calcium oscillation is assumed to involve protein kinase C (PKC), which is activated together with the calcium releases as a consequence of inositol phospholipid hydrolysis. In the present study, this issue has been investigated pharmacologically by using astrocytes cultured with and without the growth factors. The pharmacological activation of PKC largely reduced the glutamate-induced oscillatory and non-oscillatory calcium increases. Meanwhile, PKC inhibitors increased the total amounts of both calcium increases without affecting the peak amplitudes and converted the calcium oscillations to non-oscillatory sustained calcium increases by abolishing the falling phases of the repetitive calcium increases. Furthermore, the pharmacological effects were consistent between both glutamate- and histamine-induced calcium oscillations. These results suggest that PKC up-regulates the removal of cytosolic calcium in astrocytes, and this up-regulation is essential for calcium oscillation in astrocytes cultured with growth factors.
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Affiliation(s)
- Mitsuhiro Morita
- Department of Biology, Kobe University Graduate School of Science, Kobe, 657-8501, Japan; School of Life Science, Tokyo University of Pharmacy and Life Science, Tokyo, 192-0392, Japan.
| | - Akira Nakane
- School of Life Science, Tokyo University of Pharmacy and Life Science, Tokyo, 192-0392, Japan
| | - Shohei Maekawa
- Department of Biology, Kobe University Graduate School of Science, Kobe, 657-8501, Japan
| | - Yoshihisa Kudo
- School of Life Science, Tokyo University of Pharmacy and Life Science, Tokyo, 192-0392, Japan
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Gotoh Y, Kita S, Fujii M, Tagashira H, Horie I, Arai Y, Uchida S, Iwamoto T. Genetic knockout and pharmacologic inhibition of NCX2 cause natriuresis and hypercalciuria. Biochem Biophys Res Commun 2015; 456:670-5. [DOI: 10.1016/j.bbrc.2014.12.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/04/2014] [Indexed: 10/24/2022]
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A new cell-penetrating peptide that blocks the autoinhibitory XIP domain of NCX1 and enhances antiporter activity. Mol Ther 2014; 23:465-76. [PMID: 25582710 DOI: 10.1038/mt.2014.231] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 11/26/2014] [Indexed: 02/07/2023] Open
Abstract
The plasma membrane Na(+)/Ca(2+) exchanger (NCX) is a high-capacity ionic transporter that exchanges 3Na(+) ions for 1Ca(2+) ion. The first 20 amino acids of the f-loop, named exchanger inhibitory peptide (XIP(NCX1)), represent an autoinhibitory region involved in the Na(+)-dependent inactivation of the exchanger. Previous research has shown that an exogenous peptide having the same amino acid sequence as the XIP(NCX1) region exerts an inhibitory effect on NCX activity. In this study, we identified another regulatory peptide, named P1, which corresponds to the 562-688aa region of the exchanger. Patch-clamp analysis revealed that P1 increased the activity of the exchanger, whereas the XIP inhibited it. Furthermore, P1 colocalized with NCX1 thus suggesting a direct binding interaction. In addition, site-directed mutagenesis experiments revealed that the binding and the stimulatory effect of P1 requires a functional XIP(NCX1) domain on NCX1 thereby suggesting that P1 increases the exchanger activity by counteracting the action of this autoinhibitory sequence. Taken together, these results open a new strategy for developing peptidomimetic compounds that, by mimicking the functional pharmacophore of P1, might increase NCX1 activity and thus exert a therapeutic action in those diseases in which an increase in NCX1 activity might be helpful.
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Nishiyama K, Morioka A, Kita S, Nakajima H, Iwamoto T, Azuma YT, Takeuchi T. Na/Ca(2+) exchanger 1 transgenic mice display increased relaxation in the distal colon. Pharmacology 2014; 94:230-8. [PMID: 25427675 DOI: 10.1159/000363246] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 04/28/2014] [Indexed: 01/11/2023]
Abstract
Na(+)/Ca(2+) exchanger 1 (NCX1) is a plasma membrane transporter involved in regulating intracellular Ca(2+) concentrations. NCX1 is critical for Ca(2+) regulation in cardiac muscle, vascular smooth muscle and nerve fibers. However, little is known about the physiological role of NCX1 in gastrointestinal motility. To determine the role of NCX1 in gastrointestinal tissues, we examined electric field stimulation (EFS)-induced responses in the longitudinal smooth muscle of the distal colon in smooth muscle-specific NCX1 transgenic mice (Tg). Tg show that NCX1 protein was overexpressed in the distal colon at a level twofold greater than that of endogenous NCX1. We found that the amplitudes of EFS-induced relaxation that persisted during EFS were greater in Tg than in wild-type mice (WT). Under the nonadrenergic, noncholinergic condition, the EFS-induced relaxation in Tg was also greater than that in WT. Inhibition of NO synthase, CO synthase, soluble guanylate cyclase (sGC), and protein kinase G (PKG) all attenuated the enhanced relaxation in Tg, demonstrating the importance of NCX1 in NO/sGC/PKG signaling. The action of NOR-1, an NO donor, induced enhanced relaxation in Tg compared with that in WT. Unlike NOR-1, pituitary adenylate cyclase-activating peptide and vasoactive intestinal peptide induced a similar relaxation in Tg compared with that in WT. In this study, we demonstrate that NCX1 plays an important role in smooth muscle motility in the mouse distal colon.
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Affiliation(s)
- Kazuhiro Nishiyama
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
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Nishiyama K, Azuma YT, Kita S, Azuma N, Hayashi S, Nakajima H, Iwamoto T, Takeuchi T. Na⁺/Ca²⁺ exchanger 1/2 double-heterozygote knockout mice display increased nitric oxide component and altered colonic motility. J Pharmacol Sci 2013; 123:235-45. [PMID: 24162024 DOI: 10.1254/jphs.13114fp] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The Na⁺/Ca²⁺ exchanger (NCX) is a plasma membrane transporter involved in regulating intracellular Ca²⁺ concentrations. NCX is critical for Ca²⁺ regulation in cardiac muscle, vascular smooth muscle, and nerve fibers. To determine the role of NCX1 and NCX2 in gastrointestinal tissues, we examined electric field stimulation (EFS)-induced responses in the longitudinal smooth muscle of the distal colon in NCX1 and NCX2 double-heterozygote knockoutmice (Double HET). We found that the amplitudes of EFS-induced relaxation that persisted during EFS were greater in Double HET than in wild-type mice (WT). Under the non-adrenergic, non-cholinergic (NANC) condition, EFS-induced relaxation in Double HET was similar in amplitude to that of WT. In the experiments in which l-NNA was added under NANC conditions following the EFS, the magnitudes of EFS-induced relaxation were smaller in Double HET than those in WT. In addition, an NCX inhibitor, SN-6, enhanced EFS-induced relaxation but did not affect EFS-induced relaxation under NANC condition, as in Double HET. Moreover, the magnitudes of relaxation induced by NOR-1, which generates NO, were greater in Double HET compared with WT. Similarly, SN-6 potentiated the magnitudes of NOR-1-induced relaxation. In this study, we demonstrate that NCX regulate colonic motility by altering the sensitivity of the inhibitory component.
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Affiliation(s)
- Kazuhiro Nishiyama
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Japan
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Azuma YT, Nishiyama K, Kita S, Komuro I, Nakajima H, Iwamoto T, Takeuchi T. Na(+) /Ca(2+) exchanger 2-heterozygote knockout mice display decreased acetylcholine release and altered colonic motility in vivo. Neurogastroenterol Motil 2012; 24:e600-10. [PMID: 23072505 DOI: 10.1111/nmo.12029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND The Na(+) /Ca(2+) exchanger (NCX) is a plasma membrane transporter involved in regulating intracellular Ca(2+) concentrations. NCX is critical for Ca(2+) regulation in cardiac muscle, vascular smooth muscle, and nerve fibers. However, little is known about the physiological role of NCX in the myenteric neurons and smooth muscles of the gastrointestinal tract. METHODS To determine the role of NCX1 and NCX2 in gastrointestinal tissues, we examined electric field stimulation (EFS)-induced responses in the longitudinal smooth muscle of the distal colon in NCX1- and NCX2-heterozygote knockout mice. KEY RESULTS We found that the amplitudes of EFS-induced relaxation that persisted during EFS were greater in NCX2 heterozygous mice (HET) than in wild-type mice (WT). Under the nonadrenergic, noncholinergic (NANC) condition, EFS-induced relaxation in NCX2 HET was similar in amplitude to that of WT. In addition, an NCX inhibitor, YM-244769 enhanced EFS-induced relaxation but did not affect EFS-induced relaxation under the NANC condition, as in NCX2 HET. Unlike NCX2 HET, NCX1 HET displayed no marked changes in colonic motility. These results indicate that cholinergic function in the colon is altered in NCX2 HET. The magnitude of acetylcholine (ACh)-induced contraction in NCX2 HET was similar to that in WT. In contrast, EFS-induced ACh release was reduced in NCX2 HET compared with that in WT. CONCLUSIONS & INFERENCES In this study, we demonstrate that NCX2 regulates colonic motility by altering ACh release onto the myenteric neurons of the distal colon.
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Affiliation(s)
- Y T Azuma
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan.
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A new concept: Aβ1-42 generates a hyperfunctional proteolytic NCX3 fragment that delays caspase-12 activation and neuronal death. J Neurosci 2012; 32:10609-17. [PMID: 22855810 DOI: 10.1523/jneurosci.6429-11.2012] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Although the amyloid-β(1-42) (Aβ(1-42)) peptide involved in Alzheimer's disease is known to cause a dysregulation of intracellular Ca(2+) homeostasis, its molecular mechanisms still remain unclear. We report that the extracellular-dependent early increase (30 min) in intracellular calcium concentration ([Ca(2+)](i)), following Aβ(1-42) exposure, caused the activation of calpain that in turn elicited a cleavage of the Na(+)/Ca(2+) exchanger isoform NCX3. This cleavage generated a hyperfunctional form of the antiporter and increased NCX currents (I(NCX)) in the reverse mode of operation. Interestingly, this NCX3 calpain-dependent cleavage was essential for the Aβ(1-42)-dependent I(NCX) increase. Indeed, the calpain inhibitor calpeptin and the removal of the calpain-cleavage recognition sequence, via site-directed mutagenesis, abolished this effect. Moreover, the enhanced NCX3 activity was paralleled by an increased Ca(2+) content in the endoplasmic reticulum (ER) stores. Remarkably, the silencing in PC-12 cells or the knocking-out in mice of the ncx3 gene prevented the enhancement of both I(NCX) and Ca(2+) content in ER stores, suggesting that NCX3 was involved in the increase of ER Ca(2+) content stimulated by Aβ(1-42). By contrast, in the late phase (72 h), when the NCX3 proteolytic cleavage abruptly ceased, the occurrence of a parallel reduction in ER Ca(2+) content triggered ER stress, as revealed by caspase-12 activation. Concomitantly, the late increase in [Ca(2+)](i) coincided with neuronal death. Interestingly, NCX3 silencing caused an earlier activation of Aβ(1-42)-induced caspase-12. Indeed, in NCX3-silenced neurons, Aβ(1-42) exposure hastened caspase-dependent apoptosis, thus reinforcing neuronal cell death. These results suggest that Aβ(1-42), through Ca(2+)-dependent calpain activation, generates a hyperfunctional form of NCX3 that, by increasing Ca(2+) content into ER, delays caspase-12 activation and thus neuronal death.
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Ferreira JCB, Mochly-Rosen D, Boutjdir M. Regulation of cardiac excitability by protein kinase C isozymes. Front Biosci (Schol Ed) 2012. [PMID: 22202075 DOI: 10.2741/283] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cardiac excitability and electrical activity are determined by the sum of individual ion channels, gap junctions and exchanger activities. Electrophysiological remodeling during heart disease involves changes in membrane properties of cardiomyocytes and is related to higher prevalence of arrhythmia-associated morbidity and mortality. Pharmacological and genetic manipulation of cardiac cells as well as animal models of cardiovascular diseases are used to identity changes in electrophysiological properties and the molecular mechanisms associated with the disease. Protein kinase C (PKC) and several other kinases play a pivotal role in cardiac electrophysiological remodeling. Therefore, identifying specific therapies that regulate these kinases is the main focus of current research. PKC, a family of serine/threonine kinases, has been implicated as potential signaling nodes associated with biochemical and biophysical stress in cardiovascular diseases. In this review, we describe the role of PKC isozymes that are involved in cardiac excitability and discuss both genetic and pharmacological tools that were used, their attributes and limitations. Selective and effective pharmacological interventions to normalize cardiac electrical activities and correct cardiac arrhythmias will be of great clinical benefit.
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Berberián G, Podjarny A, DiPolo R, Beaugé L. Metabolic regulation of the squid nerve Na⁺/Ca²⁺ exchanger: recent kinetic, biochemical and structural developments. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 108:47-63. [PMID: 21964458 DOI: 10.1016/j.pbiomolbio.2011.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 08/30/2011] [Accepted: 09/13/2011] [Indexed: 11/25/2022]
Abstract
The Na⁺/Ca²⁺ exchangers are structural membrane proteins, essential for the extrusion of Ca²⁺ from most animal cells. Apart from the transport sites, they have several interacting ionic and metabolic sites located at the intracellular loop of the exchanger protein. One of these, the intracellular Ca²⁺ regulatory sites, are essential and must be occupied by Ca²⁺ to allow any type of ion (Na⁺ or Ca²⁺) translocation. Intracellular protons and Na⁺ are inhibitory by reducing the affinity of the regulatory sites for Ca²⁺; MgATP stimulates by antagonizing H⁺ and Na⁺. We have proposed a kinetic scheme to explain all ionic and metabolic regulation of the squid nerve Na⁺/Ca²⁺ exchanger. This model uniquely accounts for most of the new kinetic data provided here; however, none of the existing models can explain the trans effects of the Ca(i)²⁺-regulatory sites on external cation transport sites; i.e. all models are incomplete. MgATP up-regulation of the squid Na⁺/Ca²⁺ exchanger requires a cytosolic protein, which has been recently identified as a member of the lipocalin super family of Lipid Binding Proteins (LBP or FABP) of 132 amino acids (ReP1-NCXSQ, access to GenBank EU981897). This protein was cloned, expressed and purified. To be active, ReP1-NCXSQ must be phosphorylated from MgATP by a kinase present in the plasma membrane. Phosphorylated ReP1-NCXSQ can stimulate the exchanger in the absence of ATP. Experiments with proteoliposomes proved that this up-regulation can take place just with the lipid membrane and the exchanger protein. The structure of ReP1-NCXSQ predicted from the amino acid sequence has been confirmed by X-ray crystal analysis; it has a "barrel" formed by ten beta sheets and two alpha helices, with a lipid coordinated by hydrogen bonds with Arg 126 and Tyr 128.
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Affiliation(s)
- Graciela Berberián
- Laboratorio de Biofísica, Instituto de Investigación Médica "Mercedes y Martín Ferreyra" (INIMEC-CONICET), Casilla de Correo 389, 5000 Córdoba, Argentina
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Barman P, Choisy SCM, Hancox JC, James AF. β-Adrenoceptor/PKA-stimulation, Na(+)-Ca(2+) exchange and PKA-activated Cl(-) currents in rabbit cardiomyocytes: a conundrum. Cell Calcium 2011; 49:233-9. [PMID: 21439639 PMCID: PMC3092849 DOI: 10.1016/j.ceca.2011.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Investigations into the functional modulation of the cardiac Na(+)-Ca(2+) exchanger (NCX) by acute β-adrenoceptor/PKA stimulation have produced conflicting results. Here, we investigated (i) whether or not β-adrenoceptor activation/PKA stimulation activates current in rabbit cardiac myocytes under NCX-'selective' conditions and (ii) if so, whether a PKA-activated Cl(-)-current may contribute to the apparent modulation of NCX current (I(NCX)). Whole-cell voltage-clamp experiments were conducted at 37°C on rabbit ventricular and atrial myocytes. The β-adrenoceptor-activated currents both in NCX-'selective' and Cl(-)-selective recording conditions were found to be sensitive to 10mM Ni(2+). In contrast, the PKA-activated Cl(-) current was not sensitive to Ni(2+), when it was activated downstream to the β-adrenoceptors using 10μM forskolin (an adenylyl cyclase activator). When 10μM forskolin was applied under NCX-selective recording conditions, the Ni(2+)-sensitive current did not differ between control and forskolin. These findings suggest that in rabbit myocytes: (a) a PKA-activated Cl(-) current contributes to the Ni(2+)-sensitive current activated via β-adrenoceptor stimulation under recording conditions previously considered selective for I(NCX); (b) downstream activation of PKA does not augment Ni(2+)-sensitive I(NCX), when this is measured under conditions where the Ni(2+)-sensitive PKA-activated Cl(-) current is not present.
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Affiliation(s)
- Palash Barman
- Bristol Heart Institute, Cardiovascular Research Laboratories, School of Physiology & Pharmacology, Medical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
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Wanichawan P, Louch WE, Hortemo KH, Austbø B, Lunde PK, Scott JD, Sejersted OM, Carlson CR. Full-length cardiac Na+/Ca2+ exchanger 1 protein is not phosphorylated by protein kinase A. Am J Physiol Cell Physiol 2011; 300:C989-97. [PMID: 21289289 DOI: 10.1152/ajpcell.00196.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cardiac Na(+)/Ca(2+) exchanger 1 (NCX1) is an important regulator of intracellular Ca(2+) homeostasis and cardiac function. Several studies have indicated that NCX1 is phosphorylated by the cAMP-dependent protein kinase A (PKA) in vitro, which increases its activity. However, this finding is controversial and no phosphorylation site has so far been identified. Using bioinformatic analysis and peptide arrays, we screened NCX1 for putative PKA phosphorylation sites. Although several NCX1 synthetic peptides were phosphorylated by PKA in vitro, only one PKA site (threonine 731) was identified after mutational analysis. To further examine whether NCX1 protein could be PKA phosphorylated, wild-type and alanine-substituted NCX1-green fluorescent protein (GFP)-fusion proteins expressed in human embryonic kidney (HEK)293 cells were generated. No phosphorylation of full-length or calpain- or caspase-3 digested NCX1-GFP was observed with purified PKA-C and [γ-(32)P]ATP. Immunoblotting experiments with anti-PKA substrate and phosphothreonine-specific antibodies were further performed to investigate phosphorylation of endogenous NCX1. Phospho-NCX1 levels were also not increased after forskolin or isoproterenol treatment in vivo, in isolated neonatal cardiomyocytes, or in total heart homogenate. These data indicate that the novel in vitro PKA phosphorylation site is inaccessible in full-length as well as in calpain- or caspase-3 digested NCX1 protein, suggesting that NCX1 is not a direct target for PKA phosphorylation.
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Affiliation(s)
- Pimthanya Wanichawan
- Institute for Experimental Medical Research, Oslo Univ. Hospital, Ullevaal, Oslo, Norway.
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Brini M, Carafoli E. The plasma membrane Ca²+ ATPase and the plasma membrane sodium calcium exchanger cooperate in the regulation of cell calcium. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a004168. [PMID: 21421919 DOI: 10.1101/cshperspect.a004168] [Citation(s) in RCA: 204] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Calcium is an ambivalent signal: it is essential for the correct functioning of cell life, but may also become dangerous to it. The plasma membrane Ca(2+) ATPase (PMCA) and the plasma membrane Na(+)/Ca(2+) exchanger (NCX) are the two mechanisms responsible for Ca(2+) extrusion. The NCX has low Ca(2+) affinity but high capacity for Ca(2+) transport, whereas the PMCA has a high Ca(2+) affinity but low transport capacity for it. Thus, traditionally, the PMCA pump has been attributed a housekeeping role in maintaining cytosolic Ca(2+), and the NCX the dynamic role of counteracting large cytosolic Ca(2+) variations (especially in excitable cells). This view of the roles of the two Ca(2+) extrusion systems has been recently revised, as the specific functional properties of the numerous PMCA isoforms and splicing variants suggests that they may have evolved to cover both the basal Ca(2+) regulation (in the 100 nM range) and the Ca(2+) transients generated by cell stimulation (in the μM range).
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Affiliation(s)
- Marisa Brini
- Department of Biological Chemistry, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy.
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Protein Quality Control, Retention, and Degradation at the Endoplasmic Reticulum. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 292:197-280. [DOI: 10.1016/b978-0-12-386033-0.00005-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Secondo A, Molinaro P, Pannaccione A, Esposito A, Cantile M, Lippiello P, Sirabella R, Iwamoto T, Di Renzo G, Annunziato L. Nitric Oxide Stimulates NCX1 and NCX2 but Inhibits NCX3 Isoform by Three Distinct Molecular Determinants. Mol Pharmacol 2010; 79:558-68. [DOI: 10.1124/mol.110.069658] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Inokuchi Y, Shimazawa M, Nakajima Y, Komuro I, Matsuda T, Baba A, Araie M, Kita S, Iwamoto T, Hara H. A Na+/Ca2+ exchanger isoform, NCX1, is involved in retinal cell death after N-methyl-D-aspartate injection and ischemia-reperfusion. J Neurosci Res 2009; 87:906-17. [PMID: 18855935 DOI: 10.1002/jnr.21906] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We investigated the expression of Na(+)/Ca(2+) exchanger (NCX) and the functional role of NCX in retinal damage by using NCX1-heterozygous deficient mice (NCX1(+/-)) and SEA0400 (2-[4-[(2,5-difluorophenyl)methoxy] phenoxy]-5-ethoxyaniline), a selective NCX inhibitor in vivo. We also examined the role of NCX in oxygen-glucose deprivation (OGD) stress with a retinal ganglion cell line (RGC-5) cell culture in vitro. The expression of NCX1 was confirmed and entirely localized in retina by immunoblotting and immunohistochemistry, respectively. NCX1(+/-) mice possessed significant protection against retinal damage induced by intravitreal injection of N-methyl-D-aspartate (NMDA). SEA0400 at 3 and 10 mg/kg significantly reduced NMDA- or high intraocular pressure-induced retinal cell damage in mice. Furthermore, SEA0400 reduced the number of TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling)-positive cells and the expression of phosphorylated mitogen-activated protein kinases (ERK1/2, JNK, p38) induced by NMDA injection. In RGC-5, SEA0400 at 0.3 and 1 microM significantly inhibited OGD-induced cell damage. OGD-induced cell damage was aggravated by ouabain (a Na(+),K(+)-ATPase inhibitor) at 100 microM, and this increased damage was significantly reduced by SEA0400 at 1 microM. In conclusion, these results suggest that NCX1 may play a role in retinal cell death induced by NMDA and ischemia-reperfusion.
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Affiliation(s)
- Y Inokuchi
- Department of Biofunctional Evaluation, Molecular Pharmacology, Gifu Pharmaceutical University, Gifu, Japan
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Soma S, Kuwashima H, Matsumura C, Kimura T. Involvement of protein kinase C in the regulation of Na+/Ca2+ exchanger in bovine adrenal chromaffin cells. Clin Exp Pharmacol Physiol 2009; 36:717-23. [PMID: 19207723 DOI: 10.1111/j.1440-1681.2009.05140.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
1. The Na(+)/Ca(2+) exchanger (NCX) exchanges Na+ and Ca(2+) bidirectionally through the forward mode (Ca(2+) extrusion) or the reverse mode (Ca(2+) influx). The present study was undertaken to clarify the role of protein kinase C (PKC) in the regulation of NCX in bovine adrenal chromaffin cells. The Na(+)-loaded cells were prepared by treatment with 100 micromol/L ouabain and 50 micromol/L veratridine. Incubation of Na(+)-loaded cells with Na(+)-free solution in the presence of the Ca(2+) channel blockers nicardipine (3 micromol/L) and omega-conotoxin MVIIC (0.3 micromol/L) caused Ca(2+) uptake and catecholamine release. 2. The Na(+)-dependent Ca(2+) uptake and catecholamine release were inhibited by 2-[4-[(2,5-difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline (SEA0400; 1 micromol/L) and 2-[2-[4-(4-nitrobenzyloxy)phenyl]isothiourea (KB-R7943; 10 micromol/L), both NCX inhibitors. These results indicate that the Na(+)-dependent responses are mostly due to activation of the NCX working in the reverse mode. 3. In addition, we examined the effects of PKC inhibitors and an activator on the NCX-mediated Ca(2+) uptake and catecholamine release. Bisindolylmaleimide I (0.3-10 micromol/L) and chelerythrine (3-100 micromol/L), both PKC inhibitors, inhibited NCX-mediated responses. In contrast, phorbol 12,13-dibutyrate (0.1-10 micromol/L), a PKC activator, enhanced the responses. Bisindolylmaleimide I and chelerythrine, at effective concentrations for inhibition of Na(+)-dependent catecholamine release, had a little or no effect on high K(+)-induced catecholamine release in intact cells or on Ca(2+)-induced catecholamine release in beta-escin-permeabilized cells. 4. These results suggest that PKC is involved in the activation of NCX in bovine adrenal chromaffin cells.
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Affiliation(s)
- Shin Soma
- Department of Pharmacology, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.
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Maeda S, Sakamoto K, Matsuoka I, Iwamoto T, Kimura J. Lysophosphatidylcholine Increases Na+/Ca2+ Exchanger Expression via RhoB-Geranylgeranylation in H9c2 Cells. J Pharmacol Sci 2009; 109:565-72. [DOI: 10.1254/jphs.08253fp] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Kang TM. PKC-Independent Stimulation of Cardiac Na/Ca Exchanger by Staurosporine. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2008; 12:259-65. [PMID: 19967065 DOI: 10.4196/kjpp.2008.12.5.259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
[Ca(2+)](i) transients by reverse mode of cardiac Na(+)/Ca(2+) exchanger (NCX1) were recorded in fura-2 loaded BHK cells with stable expression of NCX1. Repeated stimulation of reverse NCX1 produced a long-lasting decrease of Ca(2+) transients ('rundown'). Rundown of NCX1 was independent of membrane PIP(2) depletion. Although the activation of protein kinase C (PKC) was observed during the Ca(2+) transients, neither a selective PKC inhibitor (calphostin C) nor a PKC activator (PMA) changed the degrees of rundown. By comparison, a non-specific PKC inhibitor, staurosporine (STS), reversed rundown in a dose-dependent and reversible manner. The action of STS was unaffected by pretreatment of the cells with calphostin C, PMA, or forskolin. Taken together, the results suggest that the stimulation of reverse NCX1 by STS is independent of PKC and/or PKA inhibition.
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Affiliation(s)
- Tong Mook Kang
- Department of Physiology, SBRI, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea
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Zhang YH, Hancox JC. Regulation of cardiac Na+-Ca2+ exchanger activity by protein kinase phosphorylation--still a paradox? Cell Calcium 2008; 45:1-10. [PMID: 18614228 DOI: 10.1016/j.ceca.2008.05.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 04/14/2008] [Accepted: 05/27/2008] [Indexed: 11/18/2022]
Abstract
The cardiac Na+-Ca2+ exchanger (NCX) is an important regulator of intracellular ion homeostasis and cardiac function. Gaining insight into modulation of the NCX is therefore important in order to understand ion handling in the heart under physiological and pathological conditions. Typically, the functional contribution of the NCX is often regarded as "secondary" to the changes in luminal Na+ and Ca2+. Whilst it is well accepted that the NCX can be regulated by various factors, including the concentrations of transported ions, direct receptor-mediated modulation of the cardiac NCX is more controversial. Evidence from several different laboratories supports the notion that the cardiac NCX is a direct target of neurotransmitters and hormones and their downstream signalling pathways; however, the issue remains unresolved due to conflicting data showing a lack of direct modulation. The present review summarizes overall findings regarding the modulation of the cardiac NCX, in particular on molecular mechanisms of direct phosphorylation of NCX by beta-adrenergic/adenylate cyclase/protein kinase A and (for comparative purposes) on endothelin-1/protein kinase C signalling pathways. It also aims to consider whether it is currently possible to reconcile discrepancies between studies in the interpretation of the regulation of the cardiac NCX by agents stimulating the beta-adrenoceptor/PKA pathway.
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Affiliation(s)
- Yin Hua Zhang
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom.
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Li L, Watanabe Y, Matsuoka I, Kimura J. Acidic preconditioning inhibits Na+/H+ and Na+/Ca2+ exchanger interaction via PKCepsilon in guinea-pig ventricular myocytes. J Pharmacol Sci 2008; 107:309-16. [PMID: 18603829 DOI: 10.1254/jphs.08049fp] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
An interaction between the Na(+)/Ca(2+) exchanger (NCX) and the Na(+)/H(+) exchanger (NHE) induces reperfusion injury. We investigated the effect of brief repetitive acidosis as acidic preconditioning on NCX and NHE interaction during recovery from acidosis. NCX current with the reversal potential was measured in guinea-pig ventricular myocytes using the whole-cell voltage clamp. The cells were exposed to 5 min of acidosis preceded by two episodes of brief acidosis as acidic preconditioning. Acidosis inhibited NCX current and upon recovery shifted its reversal potential in the negative direction. The shift was prevented by cariporide, but was augmented by a high concentration of phorbol 13-myristate acetate (PMA). Acidic preconditioning prevented the shift, but not in the presence of a selective PKCepsilon inhibitor. A low concentration of PMA, which activates PKCepsilon selectively, prevented the shift, but together with PKCepsilon inhibitor (epsilonV1-2) restored the shift during recovery. 5-Hydroxydecanoate inhibited the effects of acidic preconditioning and those of both low and high concentrations of PMA. The negative shift of NCX reversal potential during recovery from acidosis may be due to [Na(+)](i) accumulation by the NHE. Acidic preconditioning prevented the shift most likely by activating PKCepsilon, which in turn inhibited the NHE. The NHE-NCX interaction may be one of the important end-effectors of preconditioning.
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Affiliation(s)
- Libing Li
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Fukushima, Japan
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33
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Abstract
Calcium (Ca) is a universal intracellular second messenger. In muscle, Ca is best known for its role in contractile activation. However, in recent years the critical role of Ca in other myocyte processes has become increasingly clear. This review focuses on Ca signaling in cardiac myocytes as pertaining to electrophysiology (including action potentials and arrhythmias), excitation-contraction coupling, modulation of contractile function, energy supply-demand balance (including mitochondrial function), cell death, and transcription regulation. Importantly, although such diverse Ca-dependent regulations occur simultaneously in a cell, the cell can distinguish distinct signals by local Ca or protein complexes and differential Ca signal integration.
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Affiliation(s)
- Donald M Bers
- Department of Physiology and Cardiovascular Institute, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA.
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Villa-Abrille MC, Sidor A, O'Rourke B. Insulin effects on cardiac Na+/Ca2+ exchanger activity: role of the cytoplasmic regulatory loop. J Biol Chem 2008; 283:16505-13. [PMID: 18387949 DOI: 10.1074/jbc.m801424200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin can alter myocardial contractility, in part through an effect on the cardiac sarcolemmal Na(+)/Ca(2+) exchanger (NCX), but little is known about its mechanism of action. The large cytoplasmic domain (f-loop) of NCX is required for regulation by various intracellular factors, and we have shown previously that residues 562-679 are determinants of NCX inhibition by exchanger inhibitory peptide (XIP). Here we show that the same f-loop deletion eliminates the enhancement of NCX current by insulin, and we examine the signal pathways involved in the insulin response. NCX current (I(NCX)) was measured in freshly isolated or cultured (up to 48 h) adult guinea pig myocytes and in myocytes expressing canine NCX1.1 with the 562-679 f-loop deletion (NCX-(Delta562-679)) via adenoviral gene transfer. I(NCX) was recorded by whole-cell patch clamp as the Ni(2+)-sensitive current at 37 degrees C with intracellular Ca(2+) buffered. Insulin (1 microm) increased I(NCX) (at +80 mV) by 110 and 83% in fresh and cultured myocytes, respectively, whereas in myocytes expressing NCX-(Delta562-679) the response was eliminated (with 100 microm XIP included to suppress any native guinea pig I(NCX)). The insulin effect on I(NCX) was not inhibited by wortmannin, a nitric-oxide synthase inhibitor, or disruption of caveolae but was blocked by chelerythrine, implicating protein kinase C, but not phosphatidylinositol-3-kinase, in the mechanism. The insulin effect was also not additive with phosphatidylinositol-4,5-bisphosphate-induced activation of I(NCX). The finding that the 562-670 f-loop domain is implicated in both XIP and receptor-mediated modulation of NCX highlights its important role in acute physiological or pathophysiological regulation of Ca(2+) balance in the heart.
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Affiliation(s)
- María Celeste Villa-Abrille
- Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, Maryland 21205, USA
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35
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Goldspink P, Ruch S, Los T, Buttrick P, García J. Maladaptation of calcium homoeostasis in aging cardiac myocytes. Pflugers Arch 2008; 456:479-87. [PMID: 18172603 DOI: 10.1007/s00424-007-0420-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 12/06/2007] [Indexed: 10/22/2022]
Abstract
With aging, the heart develops myocyte hypertrophy associated with impaired relaxation indices. To define the cellular basis of this adaptation, we examined the physiological changes that arise in calcium handling in the aging heart and contrasted the adaptations that occur following the imposition of a stimulus that alters calcium homeostasis in a young and an old heart. We utilized a cardiac-specific conditional transgenic approach to "switch on" protein kinase (PKC)-beta II expression in mice at different stages of adult life (3 and 12 months) and characterized alterations in ICa and calcium release in wild-type (WT) and PKC-beta II-expressing cells. Amplitude or voltage dependence of ICa were not significantly altered by expression of PKC-beta II at any age. No significant differences in calcium-release properties were seen with age. Upon activation of PKC-beta II, the amplitude of the calcium transient was larger, and the calcium spark frequency was greater in PKC-beta II mice compared to WT at both 3 and 12 months. Spark amplitude increased only in the 12-month PKC-beta II mice. These changes occurred in parallel with an increase in cell size (as determined by capacitance measurements) in the 12-month PKC-beta II mice but not the 3-month PKC-beta II mice. These data suggest that alterations in the calcium-handling machinery of the cardiocyte differ in the context of age and as such may predispose the older heart to the development of a hypertrophic phenotype.
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Affiliation(s)
- Paul Goldspink
- Department of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
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36
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Abstract
Mammalian Na+/Ca2+ exchangers are members of three branches of a much larger family of transport proteins [the CaCA (Ca2+/cation antiporter) superfamily] whose main role is to provide control of Ca2+ flux across the plasma membranes or intracellular compartments. Since cytosolic levels of Ca2+ are much lower than those found extracellularly or in sequestered stores, the major function of Na+/Ca2+ exchangers is to extrude Ca2+ from the cytoplasm. The exchangers are, however, fully reversible and thus, under special conditions of subcellular localization and compartmentalized ion gradients, Na+/Ca2+ exchangers may allow Ca2+ entry and may play more specialized roles in Ca2+ movement between compartments. The NCX (Na+/Ca2+ exchanger) [SLC (solute carrier) 8] branch of Na+/Ca2+ exchangers comprises three members: NCX1 has been most extensively studied, and is broadly expressed with particular abundance in heart, brain and kidney, NCX2 is expressed in brain, and NCX3 is expressed in brain and skeletal muscle. The NCX proteins subserve a variety of roles, depending upon the site of expression. These include cardiac excitation-contraction coupling, neuronal signalling and Ca2+ reabsorption in the kidney. The NCKX (Na2+/Ca2+-K+ exchanger) (SLC24) branch of Na+/Ca2+ exchangers transport K+ and Ca2+ in exchange for Na+, and comprises five members: NCKX1 is expressed in retinal rod photoreceptors, NCKX2 is expressed in cone photoreceptors and in neurons throughout the brain, NCKX3 and NCKX4 are abundant in brain, but have a broader tissue distribution, and NCKX5 is expressed in skin, retinal epithelium and brain. The NCKX proteins probably play a particularly prominent role in regulating Ca2+ flux in environments which experience wide and frequent fluctuations in Na+ concentration. Until recently, the range of functions that NCKX proteins play was generally underappreciated. This situation is now changing rapidly as evidence emerges for roles including photoreceptor adaptation, synaptic plasticity and skin pigmentation. The CCX (Ca2+/cation exchanger) branch has only one mammalian member, NCKX6 or NCLX (Na+/Ca2+-Li+ exchanger), whose physiological function remains unclear, despite a broad pattern of expression.
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Affiliation(s)
- Jonathan Lytton
- Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
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Yaradanakul A, Feng S, Shen C, Lariccia V, Lin MJ, Yang J, Dong P, Yin HL, Albanesi JP, Hilgemann DW. Dual control of cardiac Na+ Ca2+ exchange by PIP(2): electrophysiological analysis of direct and indirect mechanisms. J Physiol 2007; 582:991-1010. [PMID: 17540705 PMCID: PMC2075271 DOI: 10.1113/jphysiol.2007.132712] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Cardiac Na(+)-Ca(2+) exchange (NCX1) inactivates in excised membrane patches when cytoplasmic Ca(2+) is removed or cytoplasmic Na(+) is increased. Exogenous phosphatidylinositol-4,5-bis-phosphate (PIP(2)) can ablate both inactivation mechanisms, while it has no effect on inward exchange current in the absence of cytoplasmic Na(+). To probe PIP(2) effects in intact cells, we manipulated PIP(2) metabolism by several means. First, we used cell lines with M1 (muscarinic) receptors that couple to phospholipase C's (PLCs). As expected, outward NCX1 current (i.e. Ca(2+) influx) can be strongly inhibited when M1 agonists induce PIP(2) depletion. However, inward currents (i.e. Ca(2+) extrusion) without cytoplasmic Na(+) can be increased markedly in parallel with an increase of cell capacitance (i.e. membrane area). Similar effects are incurred by cytoplasmic perfusion of GTPgammaS or the actin cytoskeleton disruptor latrunculin, even in the presence of non-hydrolysable ATP (AMP-PNP). Thus, G-protein signalling may increase NCX1 currents by destabilizing membrane cytoskeleton-PIP(2) interactions. Second, to increase PIP(2) we directly perfused PIP(2) into cells. Outward NCX1 currents increase as expected. But over minutes currents decline substantially, and cell capacitance usually decreases in parallel. Third, using BHK cells with stable NCX1 expression, we increased PIP(2) by transient expression of a phosphatidylinositol-4-phosphate-5-kinase (hPIP5KIbeta) and a PI4-kinase (PI4KIIalpha). NCX1 current densities were decreased by > 80 and 40%, respectively. Fourth, we generated transgenic mice with 10-fold cardiac-specific overexpression of PI4KIIalpha. This wortmannin-insensitive PI4KIIalpha was chosen because basal cardiac phosphoinositides are nearly insensitive to wortmannin, and surface membrane PI4-kinase activity, defined functionally in excised patches, is not blocked by wortmannin. Both phosphatidylinositol-4-phosphate (PIP) and PIP(2) were increased significantly, while NCX1 current densities were decreased by 78% with no loss of NCX1 expression. Most mice developed cardiac hypertrophy, and immunohistochemical analysis suggests that NCX1 is redistributed away from the outer sarcolemma. Cholera toxin uptake was increased 3-fold, suggesting that clathrin-independent endocytosis is enhanced. We conclude that direct effects of PIP(2) to activate NCX1 can be strongly modulated by opposing mechanisms in intact cells that probably involve membrane cytoskeleton remodelling and membrane trafficking.
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Affiliation(s)
- Alp Yaradanakul
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9040, USA
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Katanosaka Y, Kim B, Wakabayashi S, Matsuoka S, Shigekawa M. Phosphorylation of Na+/Ca2+ exchanger in TAB-induced cardiac hypertrophy. Ann N Y Acad Sci 2007; 1099:373-6. [PMID: 17446477 DOI: 10.1196/annals.1387.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Both protein kinase Calpha-dependent Na+/Ca2+ exchanger1 (NCX1) phosphorylation and calcineurin activity are required for the depression of NCX activity observed in chronically phenylephrine (PE)-treated hypertrophic neonatal rat cardiomyocytes. In this study, we explored the possibility that the same changes occur in vivo hypertrophy. In the hypertrophic hearts of thoracic aortic-banded (TAB) mice, NCX1 phosphorylation increased significantly compared with control hearts. Furthermore, the TAB-induced cardiac hypertrophy was much less prominent in transgenic mice overexpressing an NCX1 mutant having defective phosphorylation sites. These data suggest that the phosphorylation status of NCX1 may play an important role in the pathogenesis of load-induced cardiac hypertrophy.
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Affiliation(s)
- Yuki Katanosaka
- Department of Molecular Physiology, National Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan.
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39
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Shigekawa M, Katanosaka Y, Wakabayashi S. Regulation of the cardiac Na+/Ca2+ exchanger by calcineurin and protein kinase C. Ann N Y Acad Sci 2007; 1099:53-63. [PMID: 17446445 DOI: 10.1196/annals.1387.059] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Na+/Ca2+ exchanger (NCX) activity is markedly inhibited in hypertrophic neonatal rat cardiomyocytes subjected to chronic phenylephrine treatment. This inhibition is reversed partially and independently by acute inhibition of calcineurin and protein kinase C (PKC) activities. Similar NCX inhibition occurs in CCL39 cells expressing cloned wild-type NCX1, when they are infected with adenoviral vectors carrying activated calcineurin A and then treated acutely with phorbol myristoyl acetate or protein phosphatase-1 inhibitors. The data obtained with these cells suggest that calcineurin activity, PKCalpha-mediated NCX1 phosphorylation, and the central loop of NCX1 (possibly its beta1 repeat) are required for the observed NCX inhibition. We observe partial inhibition of NCX activity independent of NCX1 phosphorylation when CCL39 cells are infected with activated calcineurin A but not further treated with phorbol myristoyl acetate or phosphatase inhibitors. Calcineurin thus appears to downregulate NCX activity via two independent mechanisms, one involving NCX1 phosphorylation and the other not involving NCX1 phosphorylation. These data indicate the existence of a novel regulatory mechanism for NCX1 involving calcineurin and PKC, which may be important in cardiac pathology.
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Affiliation(s)
- Munekazu Shigekawa
- Department of Human Life Sciences, Senri-Kinran University, Fujishiro-dai 5-25-1, Suita, Osaka 565-0873, Japan.
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40
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Cheung JY, Rothblum LI, Moorman JR, Tucker AL, Song J, Ahlers BA, Carl LL, Wang J, Zhang XQ. Regulation of cardiac Na+/Ca2+ exchanger by phospholemman. Ann N Y Acad Sci 2007; 1099:119-34. [PMID: 17446450 DOI: 10.1196/annals.1387.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Phospholemman (PLM) is the first sequenced member of the FXYD family of regulators of ion transport. The mature protein has 72 amino acids and consists of an extracellular N terminus containing the signature FXYD motif, a single transmembrane (TM) domain, and a cytoplasmic C-terminal domain containing four potential sites for phosphorylation. PLM and other members of the FXYD family are known to regulate Na+-K+-ATPase. Using adenovirus-mediated gene transfer into adult rat cardiac myocytes, we showed that changes in contractility and intracellular Ca2+ homeostasis associated with PLM overexpression or downregulation are not consistent with the effects expected from inhibition of Na+-K+-ATPase by PLM. Additional studies with heterologous expression of PLM and cardiac Na+/Ca2+ exchanger 1 (NCX1) in HEK293 cells and cardiac myocytes isolated from PLM-deficient mice demonstrated by co-localization, co-immunoprecipitation, and electrophysiological and radioactive tracer uptake techniques that PLM associates with NCX1 in the sarcolemma and transverse tubules and that PLM inhibits NCX1, independent of its effects on Na+-K+-ATPase. Mutational analysis indicates that the cytoplasmic domain of PLM is required for its regulation of NCX1. In addition, experiments using phosphomimetic and phospho-deficient PLM mutants, as well as activators of protein kinases A and C, indicate that PLM phosphorylated at serine68 is the active form that inhibits NCX1. This is in sharp contrast to the finding that the unphosphorylated PLM form inhibits Na+-K+-ATPase. We conclude that PLM regulates cardiac contractility by modulating the activities of NCX and Na+-K+-ATPase.
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Affiliation(s)
- Joseph Y Cheung
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA.
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41
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Kita S, Furuta A, Takano Y, Iwamoto T. The Role of Na+/Ca2+ Exchanger in Endothelin-1-Aggravated Hypoxia/Reoxygenation-Induced Injury in Renal Epithelial Cells. Ann N Y Acad Sci 2007; 1099:473-7. [PMID: 17446489 DOI: 10.1196/annals.1387.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We analyzed the role of the Na+/Ca2+ exchanger (NCX) in endothelin-1-aggravated hypoxia/reoxygenation-induced injury in renal epithelial LLC-PK1 cells. KB-R7943, a selective NCX inhibitor, suppressed hypoxia/reoxygenation-induced cell damage, whereas overexpression of NCX1 into cells enhanced it. Endothelin-1 significantly aggravated hypoxia/reoxygenation-induced injury in parental and NCX1-overexpressing LLC-PK1 cells. Such aggravation by endothelin-1 was not observed in cells overexpressing a deregulated NCX1 mutant, which displays no protein kinase C-dependent activation. These results suggest that Ca2+ overload via NCX plays a critical role in hypoxia/reoxygenation-induced renal tubular injury, and that endothelin-1 aggravates the cell damage through the activation of NCX.
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Affiliation(s)
- Satomi Kita
- Department of Pharmacology, School of Medicine, Fukuoka University, Fukuoka 814-0180, Japan
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42
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Ruknudin AM, Wei SK, Haigney MC, Lederer WJ, Schulze DH. Phosphorylation and Other Conundrums of Na/Ca Exchanger, NCX1. Ann N Y Acad Sci 2007; 1099:103-18. [PMID: 17446449 DOI: 10.1196/annals.1387.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The Na+/Ca2+ exchanger (NCX) is an important Ca2+ transport mechanism in virtually all cells in the body. There are three genes that control the expression of NCX in mammals. There are at least 16 alternatively spliced isoforms of NCX1 that target muscle and nerve and other tissues. Here we briefly discuss three remarkable regulatory issues or "conundrums" that involve the most prevalently expressed gene, NCX1. (1) How is NCX1 regulated by phosphorylation? We suggest that the macromolecular complex of NCX1 plays a critical role in the regulation of NCX. The role of the macromolecular complex and evidence supporting its existence and functional importance is presented. (2) Can there be transport block of a single "mode" of NCX1 transport by drugs or therapeutic agents? The simple answer is "no." A brief explanation is provided. (3) How can NCX1 knockout mice live? The answer is "by other compensatory regulatory mechanisms." These conundrums highlight important features in NCX1 and lay the foundation for new experiments to elucidate function and regulation of NCX1 and provide a context for investigations that seek to understand novel therapeutic agents.
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Affiliation(s)
- Abdul M Ruknudin
- Department of Microbiology and Immunology, 660 W. Redwood Street, Baltimore, MD 21201, USA.
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43
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Wang J, Zhang XQ, Ahlers BA, Carl LL, Song J, Rothblum LI, Stahl RC, Carey DJ, Cheung JY. Cytoplasmic Tail of Phospholemman Interacts with the Intracellular Loop of the Cardiac Na+/Ca2+ Exchanger. J Biol Chem 2006. [DOI: 10.1016/s0021-9258(19)84114-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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44
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Iwamoto T, Kita S. YM-244769, a novel Na+/Ca2+ exchange inhibitor that preferentially inhibits NCX3, efficiently protects against hypoxia/reoxygenation-induced SH-SY5Y neuronal cell damage. Mol Pharmacol 2006; 70:2075-83. [PMID: 16973719 DOI: 10.1124/mol.106.028464] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the pharmacological properties and interaction domains of N-(3-aminobenzyl)-6-{4-[(3-fluorobenzyl)oxy]phenoxy} nicotinamide (YM-244769), a novel potent Na(+)/Ca(2+) exchange (NCX) inhibitor, using various NCX-transfectants and neuronal and renal cell lines. YM-244769 preferentially inhibited intracellular Na(+)-dependent (45)Ca(2+) uptake via NCX3 (IC(50) = 18 nM); the inhibition was 3.8- to 5.3-fold greater than for the uptake via NCX1 or NCX2, but it did not significantly affect extracellular Na(+)-dependent (45)Ca(2+) efflux via NCX isoforms. We searched for interaction domains with YM-244769 by NCX1/NCX3-chimeric analysis and determined that the alpha-2 region in NCX1 is mostly responsible for the differential drug response between NCX1 and NCX3. Further cysteine scanning mutagenesis in the alpha-2 region identified that the mutation at Gly833 markedly reduced sensitivity to YM-244769. Mutant exchangers that display either undetectable or accelerated Na(+)-dependent inactivation, had markedly reduced sensitivity or hypersensitivity to YM-244769, respectively. YM-244769, like 2-[2-[4-(4-nitrobenzyloxyl)phenyl]ethyl]isothiourea methanesulfonate (KB-R7943), protected against hypoxia/reoxygenation-induced cell damage in neuronal SH-SY5Y cells, which express NCX1 and NCX3, more efficiently than that in renal LLC-PK(1) cells, which exclusively express NCX1, whereas 2-[4-(4-nitrobenzyloxy)benzyl]thiazolidine-4-carboxylic acid ethyl ester (SN-6) suppressed renal cell damage to a greater degree than neuronal cell damage. These protective potencies consistently correlated well with their inhibitory efficacies for the Ca(2+) uptake via NCX isoforms existing in the corresponding cell lines. Antisense knockdown of NCX1 and NCX3 in SH-SY5Y cells confirmed that NCX3 contributes to the neuronal cell damage more than NCX1. Thus, YM-244769 is not only experimentally useful as a NCX inhibitor that preferentially inhibits NCX3, but also has therapeutic potential as a new neuroprotective drug.
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Affiliation(s)
- Takahiro Iwamoto
- Department of Pharmacology, School of Medicine, Fukuoka University, 7-45-1 Nanakuma Jonanku, Fukuoka 814-0180, Japan.
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45
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Wang J, Zhang XQ, Ahlers BA, Carl LL, Song J, Rothblum LI, Stahl RC, Carey DJ, Cheung JY. Cytoplasmic tail of phospholemman interacts with the intracellular loop of the cardiac Na+/Ca2+ exchanger. J Biol Chem 2006; 281:32004-14. [PMID: 16921169 PMCID: PMC1613256 DOI: 10.1074/jbc.m606876200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phospholemman (PLM), a member of the FXYD family of small ion transport regulators, inhibits cardiac Na+/Ca2+ exchanger (NCX1). NCX1 is made up of N-terminal domain consisting of the first five transmembrane segments (residues 1-217), a large intracellular loop (residues 218-764), and a C-terminal domain comprising the last four transmembrane segments (residues 765-938). Using glutathione S-transferase (GST) pull-down assay, we demonstrated that the intracellular loop, but not the N- or C-terminal transmembrane domains of NCX1, was associated with PLM. Further analysis using protein constructs of GST fused to various segments of the intracellular loop of NCX1 suggest that PLM bound to residues 218-371 and 508-764 but not 371-508. Split Na+/Ca2+ exchangers consisting of N- or C-terminal domains with different lengths of the intracellular loop were co-expressed with PLM in HEK293 cells that are devoid of endogenous PLM and NCX1. Although expression of N-terminal but not C-terminal domain alone resulted in correct membrane targeting, co-expression of both N- and C-terminal domains was required for correct membrane targeting and functional exchange activity. NCX1 current measurements indicate that PLM decreased NCX1 current only when the split exchangers contained residues 218-358 of the intracellular loop. Co-immunoprecipitation experiments with PLM and split exchangers suggest that PLM associated with the N-terminal domain of NCX1 when it contained intracellular loop residues 218-358. TM43, a PLM mutant with its cytoplasmic tail truncated, did not co-immunoprecipitate with wild-type NCX1 when co-expressed in HEK293 cells, confirming little to no interaction between the transmembrane domains of PLM and NCX1. We conclude that PLM interacted with the intracellular loop of NCX1, most likely at residues 218-358.
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Affiliation(s)
- JuFang Wang
- Department of Cellular and Molecular Physiology and
| | | | | | - Lois L. Carl
- Department of Cellular and Molecular Physiology and
| | | | | | - Richard C. Stahl
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822
| | - David J. Carey
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822
| | - Joseph Y. Cheung
- Department of Cellular and Molecular Physiology and
- Department of Medicine, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, PA 17033; and
- Address Correspondence To: Joseph Y. Cheung, M.D., Ph.D., Department of Cellular and Molecular Physiology, Milton S. Hershey Medical Center, MC-H166, Hershey, PA 17033. Tel. (717)531-5748; Fax. (717)531-7667;
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Pulina MV, Rizzuto R, Brini M, Carafoli E. Inhibitory interaction of the plasma membrane Na+/Ca2+ exchangers with the 14-3-3 proteins. J Biol Chem 2006; 281:19645-54. [PMID: 16679322 DOI: 10.1074/jbc.m602033200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The three Na+/Ca2+ exchanger isoforms, NCX1, NCX2, and NCX3, contain a large cytoplasmic loop that is responsible for the regulation of activity. We have used 347 residues of the loop of NCX2 as the bait in a yeast two-hybrid approach to identify proteins that could interact with the exchanger and regulate its activity. Screening of a human brain cDNA library identified the epsilon and zeta isoforms of the 14-3-3 protein family as interacting partners of the exchanger. The interaction was confirmed by immunoprecipitation and in vitro binding experiments. The effect of the interaction on the homeostasis of Ca2+ was investigated by co-expressing NCX2 and 14-3-3epsilon in HeLa cells together with the recombinant Ca2+ probe aequorin; the ability of cells expressing both NCX2 and 14-3-3epsilon to dispose of a Ca2+ transient induced by an InsP3-producing agonist was substantially decreased, indicating a reduction of NCX2 activity. The 14-3-3epsilon protein also inhibited the NCX1 and NCX3 isoforms. In vitro binding experiments revealed that all three NCX isoforms interacted with multiple 14-3-3 isoforms. 14-3-3 was bound by both phosphorylated and nonphosphorylated NCX, but the phosphorylated form had much higher binding affinity.
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Affiliation(s)
- Maria V Pulina
- Venetian Institute of Molecular Medicine, and Department of Biochemistry, University of Padova, 35100 Padova, Italy
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Zhang XQ, Ahlers BA, Tucker AL, Song J, Wang J, Moorman JR, Mounsey JP, Carl LL, Rothblum LI, Cheung JY. Phospholemman inhibition of the cardiac Na+/Ca2+ exchanger. Role of phosphorylation. J Biol Chem 2006; 281:7784-92. [PMID: 16434394 PMCID: PMC1405234 DOI: 10.1074/jbc.m512092200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have demonstrated previously that phospholemman (PLM), a 15-kDa integral sarcolemmal phosphoprotein, inhibits the cardiac Na+/Ca2+ exchanger (NCX1). In addition, protein kinase A phosphorylates serine 68, whereas protein kinase C phosphorylates both serine 63 and serine 68 of PLM. Using human embryonic kidney 293 cells that are devoid of both endogenous PLM and NCX1, we first demonstrated that the exogenous NCX1 current (I(NaCa)) was increased by phorbol 12-myristate 13-acetate (PMA) but not by forskolin. When co-expressed with NCX1, PLM resulted in: (i) decreases in I(NaCa), (ii) attenuation of the increase in I(NaCa) by PMA, and (iii) additional reduction in I(NaCa) in cells treated with forskolin. Mutating serine 63 to alanine (S63A) preserved the sensitivity of PLM to forskolin in terms of suppression of I(NaCa), whereas mutating serine 68 to alanine (S68A) abolished the inhibitory effect of PLM on I(NaCa). Mutating serine 68 to glutamic acid (phosphomimetic) resulted in additional suppression of I(NaCa) as compared with wild-type PLM. These results suggest that PLM phosphorylated at serine 68 inhibited I(NaCa). The physiological significance of inhibition of NCX1 by phosphorylated PLM was evaluated in PLM-knock-out (KO) mice. When compared with wild-type myocytes, I(NaCa) was significant larger in PLM-KO myocytes. In addition, the PMA-induced increase in I(NaCa) was significantly higher in PLM-KO myocytes. By contrast, forskolin had no effect on I(NaCa) in wild-type myocytes. We conclude that PLM, when phosphorylated at serine 68, inhibits Na+/Ca2+ exchange in the heart.
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Key Words
- anova, analysis of variance
- 8-br-camp, 8-bromoadenosine 3′, 5′ cyclic monophosphate
- [ca2+]o, extracellular ca2+ concentration; cm, whole cell membrane capacitance
- cmv, cytomegalovirus
- dmem, dulbecco’s modified eagle’s medium
- dmso, dimethylsulfoxide
- egta, ethylene glycol-bis-(β-aminoethyl ether)n,n,n’,n’-tetraacetic acid
- em, membrane potential
- em., emission
- ex., excitation
- enaca, equilibrium potential for na+, ca2+ exchange current
- fbs, fetal bovine serum
- gfp, green fluorescent protein
- hek, human embryonic kidney
- hepes, n-2-hydroxyethylpiperazine-n’-2-ethanesulfonic acid
- inaca, na+, ca2+ exchange current
- ko, knock-out
- mem, minimal essential media
- ncx1, na+, ca2+ exchanger
- nima, never in mitosis a
- pka, protein kinase a
- pkc, protein kinase c
- plm, phospholemman
- pma, phorbol 12-myristate 13-acetate
- pmsf, phenylmethylsulfonyl fluoride
- pvdf, polyvinylidene difluoride
- se, standard error
- serca2, sarco(endo)plasmic reticulum ca2+-atpase
- sr, sarcoplasmic reticulum
- sds-page, sodium dodecyl sulfate- polyacrylamide gel electrophoresis
- vmax, maximum velocity
- wt, wild-type
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Affiliation(s)
| | | | - Amy L. Tucker
- Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville, VA 22908
| | | | - JuFang Wang
- Department of Cellular and Molecular Physiology and
| | - J. Randall Moorman
- Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville, VA 22908
| | - J. Paul Mounsey
- Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville, VA 22908
| | - Lois L. Carl
- Department of Cellular and Molecular Physiology and
| | | | - Joseph Y. Cheung
- Department of Cellular and Molecular Physiology and
- Department of Medicine, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, PA 17033
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Sakai Y, Kinoshita H, Saitou K, Homma I, Nobe K, Iwamoto T. Functional differences of Na+/Ca2+ exchanger expression in Ca2+ transport system of smooth muscle of guinea pig stomach. Can J Physiol Pharmacol 2006; 83:791-7. [PMID: 16333381 DOI: 10.1139/y05-079] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The plasma membrane ATP-dependent Ca2+ pump and the Na+/Ca2+ exchanger (NCX) are the major means of Ca2+ extrusion in smooth muscle. However, little is known regarding distribution and function of the NCX in guinea pig gastric smooth muscle. The expression pattern and distribution of NCX isoforms suggest a role as a regulator of Ca2+ transport in cells. Na+ pump inhibition and the consequent to removal of K+ caused gradual contraction in fundus. In contrast, the response was significantly less in antrum. Western blotting analysis revealed that NCX1 and NCX2 are the predominant NCX isoforms expressed in stomach, the former was expressed strongly in antrum, whereas the latter displayed greater expression in fundus. Isolated plasma membrane fractions derived from gastric fundus smooth muscle were also investigated to clarify the relationship between NCX protein expression and function. Na+-dependent Ca2+ uptake increased directly with Ca2+ concentration. Ca2+ uptake in Na+-loaded vesicles was markedly elevated in comparison with K+-loaded vesicles. Additionally, Ca2+ uptake by the Na+- or K+-loaded vesicles was substantially higher in the presence of A23187 than in its absence. The result can be explained based on the assumption that Na+ gradients facilitate downhill movement of Ca2+. Na+-dependent Ca2+ uptake was abolished by the monovalent cationic ionophore, monensin. NaCl enhanced Ca2+ efflux from vesicles, and this efflux was significantly inhibited by gramicidin. Results documented evidence that NCX2 isoform functionally contributes to Ca2+ extrusion and maintenance of contraction-relaxation cycle in gastric fundus smooth muscle.
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Affiliation(s)
- Yasushi Sakai
- Division of Physiolgy, Department of Occupational Therapy, School of Nursing and Rehabilitation Sciences, Yokohama, Japan.
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DiPolo R, Beaugé L. Sodium/calcium exchanger: influence of metabolic regulation on ion carrier interactions. Physiol Rev 2006; 86:155-203. [PMID: 16371597 DOI: 10.1152/physrev.00018.2005] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Na(+)/Ca(2+) exchanger's family of membrane transporters is widely distributed in cells and tissues of the animal kingdom and constitutes one of the most important mechanisms for extruding Ca(2+) from the cell. Two basic properties characterize them. 1) Their activity is not predicted by thermodynamic parameters of classical electrogenic countertransporters (dependence on ionic gradients and membrane potential), but is markedly regulated by transported (Na(+) and Ca(2+)) and nontransported ionic species (protons and other monovalent cations). These modulations take place at specific sites in the exchanger protein located at extra-, intra-, and transmembrane protein domains. 2) Exchange activity is also regulated by the metabolic state of the cell. The mammalian and invertebrate preparations share MgATP in that role; the squid has an additional compound, phosphoarginine. This review emphasizes the interrelationships between ionic and metabolic modulations of Na(+)/Ca(2+) exchange, focusing mainly in two preparations where most of the studies have been carried out: the mammalian heart and the squid giant axon. A surprising fact that emerges when comparing the MgATP-related pathways in these two systems is that although they are different (phosphatidylinositol bisphosphate in the cardiac and a soluble cytosolic regulatory protein in the squid), their final target effects are essentially similar: Na(+)-Ca(2+)-H(+) interactions with the exchanger. A model integrating both ionic and metabolic interactions in the regulation of the exchanger is discussed in detail as well as its relevance in cellular Ca(i)(2+) homeostasis.
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Affiliation(s)
- Reinaldo DiPolo
- Laboratorio de Permebilidad Ionica, Centro de Biofísica y Bioquímica, Instituío Venezolano de Investigaciones Científicas, Caracas 1020A, Venezuela.
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Benesic A, Schwerdt G, Mildenberger S, Freudinger R, Gordjani N, Gekle M. Disturbed Ca2+-signaling by chloroacetaldehyde: a possible cause for chronic ifosfamide nephrotoxicity. Kidney Int 2006; 68:2029-41. [PMID: 16221203 DOI: 10.1111/j.1523-1755.2005.00657.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Renal damage following chemotherapy with ifosfamide is attributed to the metabolic activation of the drug and the generation of chloroacetaldehyde (CAA). Little is known about the mechanism by which CAA impairs renal function. In this study the effect of CAA on intracellular Ca(2+) homeostasis in human renal proximal tubule cells (RPTEC) in primary culture was investigated. METHODS Intracellular Ca(2+) was measured using the Ca(2+)-sensitive dye fura-2. Cell viability was determined by protein content and cell number. Oncotic and apoptotic cell death was assayed using trypan blue exclusion, caspase-3 activity, and 4',6-diamino-2-phenylindole (DAPI) staining. RESULTS CAA (1.5 to 150 micromol/L) induced sustained elevations of intracellular free calcium ([Ca(2+)](i)) from 75 +/- 3 nmol/L to maximal 151 +/- 6 nmol/L. This effect was dependent on extracellular Ca(2+), but not Ca(2+) entry. The rise in [Ca(2+)](i) mediated by CAA could be attributed to inhibition of Na(+)-dependent extrusion of intracellular Ca(2+), indicating an inhibitory action of CAA on Na(+)/Ca(2+) exchange. Modulation of protein kinase A (PKA), but not protein kinase C (PKC) blunted the effect of CAA. Thus, CAA seems to inhibit Na(+)/Ca(2+) exchange by interaction with cyclic adenosine monophosphate (cAMP)-PKA-signaling. A 48-hour exposure to 15 micromol/L CAA significantly reduced cell number and protein content of RPTEC by induction of necrosis. This effect of 15 micromol/L CAA could be overcome by coadministration of the intracellular Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM). CONCLUSION First, CAA inhibits the Na+/Ca2+-exchanger. Second, this effect is dependent on PKA. Third, CAA induces necrotic rather than apoptotic cell death. Finally, disturbed Ca(2+) homeostasis via Na(+)/Ca(2+) exchange contributes to the nephrotoxic action of CAA in RPTEC.
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